E88 not the best head?

[71datsun240z]

hi all i was told that the E88 head was 2nd best. if im wrong correct me please but is there a better head if so where can i buy it? let me know plz and thanks

[hmsports]

2ManyZs enlightened me last week that the E-88 can be made better by milling it down to raise the compression some.

Most racers swear by the E-31 and that's what the major engine builders use. They are getting harder to find.

Hope that's what you wanted.

Rick

[Zvoiture]

In these days of scarce E31's....N42 seems a good 2nd choice.

steve77

[Royce]

Time to stir the pot a little. What is an E88 head? I have heard conversations from respected Z folk that there are actually 4 different E88 heads on US model Z cars!

Here is the way it was explained to me (corrections are welcome). Heads with the E88 stamped on them started around 01/71 with the series II 240Z(or late '71 model.) This head is supposed to have the same combustion chamber as the E31. Then, in 09/71 with the series III 240Z('72 model year) the combustion chamber was changed to slightly lower compression design. Next, with '73 model year the E88 head was further designed for lower emissions and finally in '74 larger exhaust valves, same size as 280Z, were put into the E88 head.

I do have several of the E88 heads on spare engines but have yet to take them appart to see if I can document any noticable differences. I myself have a hard time believing there are 4 E88 heads but have found documentation of at least 2 different E88 designs.

So which Z head to use- E31, E88, N42, N47, P79, P90 or P90A. Did I miss any? First, unless you plan on changing to round port exhaust you can rule out the N47 and P79. Next it depends on which block/pistons you will be using. If using 240, 260, 280Z block with stock crank, rod piston setup then forget the P90 & P90A unless you are going to run a turbo because the compression would be too low for performance driving.

So that leaves the E31, E88 or N42. None of these are a "bad" choice, with the exception being the emissions designed E88. But trying to identify an E88 head may be a challenge.

So that narrows us down to E31 vs. N42. The E31 is supposed to benefit from a slightly higher compression combustion chamber design but because of age and limited quantity finding one in good condition can be difficult and expensive. The N42 is slightly lower compression combustion chamber design but unlike the E31 and early E88 it has larger exhaust valves and came with hardened valve seats and guides for running unleaded fuel. Plus, there are lots more available and you can shave them to get higher compression if that is desired.

Bottom line, I am guessing that the difference between the heads may be +/- 10 HP. Unless you head is damaged you would probably get more by setting your valves correctly, getting a valve job, changing the cam, recurving your distributor or porting and polishing your head and intake manifold then by searching for a new head. But it really depends on your desired results and how much $$$ you want to spend.

Sorry for the long post! I hope it makes sense and is helpful!

[Dan]

I have two different E88 heads, the early E88 head and a later one (atleast this is what i've been told). The casting marks are different between the two and makes idetification abit easyer. The early head has a skinny E and a uniform 88 casting mark where as the later head is uniform through out the three characters (same size and thickness). The early head has notches at the bottom of each combustion chamber, and i'm told the early head has the same compression as the E31. I'v also been told that it's an easy swap to put in the larger valves in the E88 heads, has anybody done this before?. I have the early head on my 240, which i recently put on. I changed the trans and rear end too at about the same time so i couldn't say if the early E88 head gave me anymore HP than the later one. I will say that the 5 speed 3.90 R200 and Supposed high compression E88 head have made a big difference.

[Royce]

Hmmm... I'll have to take a look at the casting numbers on the E88's I have.

Regarding the valves. My E88 had been fitted with 280Z valves. I believe it is relatively simple machine work because if I remember correctly the original smaller valve seats can be machined to fit the larger valves. In other words they don't have to change the head itself. But probably best to check with Rebello or another Z engine builder to be sure.

Have fun!

[71datsun240z]

thanks man the long post was needed to justify the question i asked was a big help in deciding the head i should probably go for. now the only thing that lies ahead is what Z had the E#! head on it im willing to spend the money to get it but i dont know where to start looking. also how much would a head like that cost? i tried to budget out the money for the car and for each area of the car that i wanna focus on.


also does anybody know where i can get a 77 280z 5 speed tranny? because i want to get one for my z while i have my engine out of my car.

[hmsports]

I've been told that a good E-31 head - bare - would cost me about $150.

[71datsun240z]

bare meaning what? like what else would be needed so that it would be ready to be set onto the lower block and ready to run?

what would a ready to run e-31 head cost me? d oyou think?

[hmsports]

What I mean by bare is just the casting - no valves, springs, cam, rockers, etc.

You can get a complete Rebello E-31 head for between $1500 and $2000. My stock E-31 rebuild cost me about $800 - but I had the casting from an old engine.

It's very hard to say what a complete head would cost - and what condition it would be in. Just start posting and searching the internet. I'm sure someone on this site has one they wouldn't mind parting with.

Sorry I couldn't be more specific.

[hmsports]

Just got a line from Zed where there are three E31 heads for sale - all around $150 - go here

[71datsun240z]

nah dude every little bit helps i thank your for the info =)

[ZmeFly]

like anything with performance comes money.

i like the early E88 head on a F54 block. port polish the head polisht the combustion chambers, insert larger valves ss steel seats, a good cam and you have a great gas pump ready engine that will kick some ass

[onuthin]

hi all i was told that the E88 head was 2nd best. if im wrong correct me please but is there a better head if so where can i buy it? let me know plz and thanks

I just ran up on a F 54 block with P90 heads. I understand with flat top pistons it will have plenty of compression. I am new to this part of performance so I would like any input I cah get.

[ncz]

Hey guys I suck at searching for old threads but there was one here that linked to a guys web site that went through all of the combinations that you are talking about. He described all blocks, heads and the combinations. Sorry I can't be more specific but he had it all down, very informative. Maybe someone else knows how to get to that thread. I will keep looking

[Fun_in_my_z]

Would a L31 bolt right on to a L28? Or would you have to change something?

[ncz]

Hey what do you know, found it. Hope it helps

http://www.geocities.com/zgarage2001/engine.html

[Mr Camouflage]

Would a L31 bolt right on to a L28? Or would you have to change something?

Yes.

[onuthin]

I got my info from that sight but have been to other sites that say different. I wanted input from others that have tried combinations to see how they work

[SteveInOakland]

Quote: "I have two different E88 heads, the early E88 head and a later one (at least this is what i've been told). The casting marks are different between the two and makes identification abit easier. The early head has a skinny E and a uniform 88 casting mark where as the later head is uniform through out the three characters (same size and thickness)."


The uniform lettering of E and 88 on the later E88 heads -- was that used only on the emissions-oriented 1973 heads? I suspect it began earlier, but does anybody know? If a known 1972 head were found to have that lettering, that would tell us. (Uniform versus the skinny E.)

thanks,
Steve

[SteveInOakland]

PS -- On the E88 lettering question, there's a photo on this Zhome page:

http://zhome.com/ZCMnL/tech/E31andE88Heads.htm

showing the chamber side of a 1973-type head vs. the 1972-type. If anybody's got an E88 head loose, it would be interesting to see if any with the 1972-type chamber side have the later casting mark. (Royce?)

[Piper]

I have both a 1970 E31 head and a late 1971 (72 model year) E88 head with the small combustion chambers. The E88 is almost identical but has very slightly larger combustion chambers and flows a little better since the valves arent shrouded like the E31. The E31 bone stock produces slightly more power, but I am in the process of doing a full race build on the E88. I had it shaved .050 and shimmed the cam towers. Schneider stage 3 cam and alloy springs as well as 44mm intake and 38 mm exhaust SI racing valves. The E88 is almost done and my E31 is a fresh rebuild with less than 200 miles on it. I'm using the E31 for driving around while I am finishing the E88. After I'm done with the E31 I might be willing to sell it.

[SteveInOakland]

I have both a 1970 E31 head and a late 1971 (72 model year) E88 head with the small combustion chambers. The E88 is almost identical but has very slightly larger combustion chambers and flows a little better since the valves arent shrouded like the E31.

So on your E88 -- what's the 'E88' lettering like? Is the 'E' skinny or is it full width like the two 8s?

thanks,
Steve

[Piper]

E31 on the car right now


E88 E is as wide as 8s


Valves are pretty big on my E88 (biggest you can fit, they barely made it) and the chamber is notched under the spark plug


stock E88 valves for comparison


I ran the E88 for a few hundred miles with a slightly clogged oiler bar that scarred my stage two cam and instigated the rebuid with an internally oiling stage three cam (reason why it is dirty).

[SteveInOakland]

Great job, Piper, thanks. So we learn that although an E88 head with big 'E' same size as the 8s may be a '73, emissions-oriented head -- it may not.

Steve.

[madkaw]

Piper,
your still going to run the spray bar with the internally oiled cam? I am building my e-88 the same way with the bigger valves and some porting work and i plan to still use the spray bar too.

[Piper]

I actually wasn't planning on running the oiler bar on the stage three cam. The stage two I was running wasn't internally oiling. To run the internally oiling cam with the spray bar i would probably need a different oil pump and larger capacity pan. I wonder if that would work. You can never have too much oil.

Edit: I asked around and I guess you can run the oiler bar with an internally oiling cam using stock innards. Probably cools better than with the block off plates.

[SavannahZ]

This is a picture of what I believe is the early casting with the skinny E and the uniform 8's. I have read conflicting information that this represents the later emmision enflicted e88.

[Piper]

I have also seen later E88s with a small E and small 8s. I'll see if I can find one.

[dogma420]

Just some things to think about:

Major rebuilders that combine head combos with blocks don't recommend using an E31 or E88 on a L28 block in most instances. I can find my information but I believe that one of the builders on here would say that. DON'T quote me on that, but from past readings, I believe this to be the case, esp when I pm'd asking some questions.

Anyone spending good money on a head rebuild, isn't going to mind having to get a square port header, so I'm not sure why anyone on here would rule out the N47 or P79. Without emissions and milling until you have the desired compression, it's my impression that these can made good head choices as well.

You would obviously want to get a 280zx exhaust manifold, or what most folks would do, and that is a square exh port header.

Just some words for thought.

Have a great Holiday!

[Piper]

I'm running a bored L26 with a balanced and polished crank and a 12.5 lb flywheel. My compression ratio with the shaved E88 and stock E31 is over10:1 so they are perfect with a hotter cam. If you are running an L28 the N42 would be your best choice for a stock bolt on since it has smaller combustion chambers and bigger valves but a lower compression ratio than the E31 and E88.

[SavannahZ]

Just thought I would revive this a little since I found an interesting photo. I don't know how many casts were used in the casting of the heads, but I thought it interesting that the dimples and everything are identicle to my E88 as this pictures I yanked off a recent ebay ad. The guy selling it didn't have a pic of the underneath so I could'nt see if it was notched or not, but he said it was original to the 72' he pulled it off of???

I'm not going to be pulling my head anytime soon, hopefully, and I guess that is the only true way to tell if it's early or late...anyhow, I thought the similarities were neat.

[VaGuS510]

I read somewhere that the N42 or maybe it was the n47 head was prone to cracking. Is this true?

I was convinced to get off my butt and get out the trusty "How to Modify your Datsun/Nissan OHC engine" book.

Heres what I get from it:

E31- Combustion chambers: 42.5cc, Intake valves: 1.65in , Exhaust valves: 1.30in
Common modifications: 1.73in intake valves and 1.38in exhaust, DANGER: an E31 milled 1mm will give 11.3:1-11.5:1 compression ratio on an L28 w/ flat top pistions

E88- Combustion chambers: 44.7cc, Intake valves: 1.65in , Exhaust valves: 1.38in
Common modifications: I assume all of the same mods as the E31 but you already have the 1.38in exhaust valves, this is a great head to drop on an L28

P90- Combustion chambers: 53.6cc, Intake valves: 1.73in ?, Exhaust valves: 1.38in ?
Common modifications: Best for low compression forced induction engines

No other heads are mentioned meaning that really they probably arn't worth it. This information is assuming that the head is going to be modified (valves unshrouded, ports matched, polished, etc.) I wouldn't say after reading this that the E31 is any better then the E88, that extra compression could be recovered in other areas if you really were concerened with the 2cc difference. 2cc is significant but if you bore an L24 out 2 mm you will recover from that. Or you can stroke it to 79.0mm with an L28 crank and you will surpass the E31. With the correct setup both the E31 and E88 can achieve very simular results as far as compression.

Lastly, are intake ports on E88 1.5in? I know they are on the E31.

[montoya_fan01]

I read somewhere that the N42 or maybe it was the n47 head was prone to cracking. Is this true?

I was convinced to get off my butt and get out the trusty "How to Modify your Datsun/Nissan OHC engine" book.

Heres what I get from it:

E31- Combustion chambers: 42.5cc, Intake valves: 1.65in , Exhaust valves: 1.30in
Common modifications: 1.73in intake valves and 1.38in exhaust, DANGER: an E31 milled 1mm will give 11.3:1-11.5:1 compression ratio on an L28 w/ flat top pistions

E88- Combustion chambers: 44.7cc, Intake valves: 1.65in , Exhaust valves: 1.38in
Common modifications: I assume all of the same mods as the E31 but you already have the 1.38in exhaust valves, this is a great head to drop on an L28

P90- Combustion chambers: 53.6cc, Intake valves: 1.73in ?, Exhaust valves: 1.38in ?
Common modifications: Best for low compression forced induction engines

No other heads are mentioned meaning that really they probably arn't worth it. This information is assuming that the head is going to be modified (valves unshrouded, ports matched, polished, etc.) I wouldn't say after reading this that the E31 is any better then the E88, that extra compression could be recovered in other areas if you really were concerened with the 2cc difference. 2cc is significant but if you bore an L24 out 2 mm you will recover from that. Or you can stroke it to 79.0mm with an L28 crank and you will surpass the E31. With the correct setup both the E31 and E88 can achieve very simular results as far as compression.

Lastly, are intake ports on E88 1.5in? I know they are on the E31.

This information you got from the book is at least incomplete. There are at least 2 varieties of E88 head (there may be a 3rd). The combustion chamber volumes of the 2 E88's that I know of are different.

[SavannahZ]

I was referring more to the casting mark similarities of potentially the early or late head. My engine is an ATK rebuild on an L26. I have read that the lettering similiar to my "E88" have been known to be both early and late. If I do have an later head, and the ebay in fact was an early, that means they are around three years difference and used the same cast...right?

[wishihadaz]

I read somewhere that the N42 or maybe it was the n47 head was prone to cracking. Is this true?

I was convinced to get off my butt and get out the trusty "How to Modify your Datsun/Nissan OHC engine" book.

Heres what I get from it:

E31- Combustion chambers: 42.5cc, Intake valves: 1.65in , Exhaust valves: 1.30in
Common modifications: 1.73in intake valves and 1.38in exhaust, DANGER: an E31 milled 1mm will give 11.3:1-11.5:1 compression ratio on an L28 w/ flat top pistions

E88- Combustion chambers: 44.7cc, Intake valves: 1.65in , Exhaust valves: 1.38in
Common modifications: I assume all of the same mods as the E31 but you already have the 1.38in exhaust valves, this is a great head to drop on an L28

P90- Combustion chambers: 53.6cc, Intake valves: 1.73in ?, Exhaust valves: 1.38in ?
Common modifications: Best for low compression forced induction engines

No other heads are mentioned meaning that really they probably arn't worth it. This information is assuming that the head is going to be modified (valves unshrouded, ports matched, polished, etc.) I wouldn't say after reading this that the E31 is any better then the E88, that extra compression could be recovered in other areas if you really were concerened with the 2cc difference. 2cc is significant but if you bore an L24 out 2 mm you will recover from that. Or you can stroke it to 79.0mm with an L28 crank and you will surpass the E31. With the correct setup both the E31 and E88 can achieve very simular results as far as compression.

Lastly, are intake ports on E88 1.5in? I know they are on the E31.

On the contrary!

It depends on what that head is mated to, and if you plan on just bolting it together or modifying it.
You have to consider what the sum of your build-up will consist of including induction, exhaust, and ignition.

The following is an except from one of the best "head forums" I have ever read.
If you take the time to read this then I invite you to look at the L6 forum on our sister site HybridZ. ( By Paul Rushman)

The biggest air flow restriction in the Datsun L-series head is the valve curtain area, i.e. the region between the valve head and the valve seat when the valve is OFF the seat. In all my L series engine builds, unshrouding the valves is always the first place I start. Even on mild street heads, I perform moderate valve unshrouding. Next, if the head is a square port head and will be used in a race only application I’ll widen the bowl to slow down the flow of air in this region. This allows the exhausting gasses to transition from the vertical plane out of the chamber to the horizontal plane on its way to the header with less chance of loosing the laminar air flow across the port floor. In dong this, the laminar air flow across the port floor will remain, (keeps the boundary layer intact), if this laminar flow separates from the port floor you will now have turbulence and this will restrict air flow considerably. (you may or not be able to catch this on a flow bench as a flow bench doesn’t measure the dynamic air flow in and out of the ports. I’ll expand on that at the end of this post). If the head has the round exhaust ports with the liners, all I do is blend the back of the valve seat into the liner. All of the heads I do, whether for street or full race, also receive a nice 5 angle valve seat, (sometimes only 4 angles can be performed do to space constraints), that I perform in house here at Rusch Motor Sports using Sunnen seat cutters, (I’ll be offering radius seats soon), and the valves are treated to a 30 degree back cut and the exhaust valves sometimes even get a nice little 45 degree chamfer on the chamber side of the head. All this extra valve and seat work mostly benefits air flow at low valve lifts, i.e. as the valves leave and return back to the seat itself.

Here is my personal take on the L-series heads.
E-31 and the early E-88 heads with the E-31 chambers are decent heads. They have the same potential as the other N-series heads when rules permit extensive carving. My opinion is the best place for the E-31 and the early E-88 is for a restoration project, or for a performance application where class rules dictate no material can be added to the chambers, no carving can be performed on the head and the update/backdate rules apply to the engine as an assembly, then these heads are a great choice. Now if you are not bound by those kinds of rules, you do have other choices available and being as the E-31 is becoming so rare now, these other heads are an easier option from a financial and availability stand point.
The N-42 head is a great maximum effort race head if class rules allow extensive carving and welding to the head. In this case, weld the chambers, open the exhaust ports as described above, perform some serious valve unshrouding and “waa laa”, you now have a wonderful maximum effort race head that would SUCK on a street engine. (Side note; If you intend on having your valves unshrouded and have not done this type of work before, you are best served leaving this to a qualified experienced engine builder, preferably one that has been successful in extracting noticeable to impressive documented performance gains. If you are not sure what you are doing, do not attempt to unshroud the valves yourself. In experience can hinder the flow worse than what the heads were stock.) Of course there is more to building/machining/porting a maximum effort cylinder heading than just welding a chamber and/or unshrouding valves. There are items such as setting spring heights, clearancing the retainers, stem seals, and guides for the mega lift cam, deciding on just how far to go with oversize valves even to the extreme of offsetting the valve guides to allow even BIGGER valves if the cylinder bore permits, etc.
The Z car N-47 head is a great street head. This head becomes almost ideal for the mild to hot street engine and even the mild to moderate race engine especially if the chambers can be welded up, (pretty much turns this head into the Maxima N-47 head which is a slightly more efficient chamber than the E-31). This “peanut” or “kidney” shaped chamber when used with flat top pistons or matching* dished pistons gives the ideal quench area which makes for a more efficient combustion process. To make use of this “kidney” shaped chamber on an L-28 running pump gas you will need matching* pistons. What I mean by “matching* pistons”, is a set of custom pistons from JE or other comparable source that has CnC the dish directly under the open portion of the “kidney” shaped chamber, not the entire surface area of the piston as is the OE 1975-1980 L-28 and all L-28-ET pistons. Any how, with this ideal squish, the engines optimum ignition advance will be less than the open chamber heads optimum ignition advance due to the more efficient chamber design. This happens because the flame front doesn’t have as far to travel to consume the entire air fuel mixture within cylinder, it now is in smaller area so the flame front doesn’t have to travel all the way to the other side of the cylinder during the ignition sequence. To better understand this concept, just visualize the open combustion chamber as being a flat wide circular disc, the diameter of the cylinder itself containing the air fuel mixture with the spark plug on one side, vs a small kidney shaped ball containing the same volume of air and fuel. Ideally a sphere shaped chamber with the spark plug in the dead center would be perfect, since that isn’t realistic, tuners just try and get as close to this ideal as possible. Some engines came for the factory much closer to this ideal, ala HEMI heads, etc. As for those round exhaust liners in the N-47 and P-79 heads, they actually flow VERY well. The liners offer a nice gentle radius as the air flow transitions from a vertical flow out of the chamber to the horizontal plane where it meets the header which keeps the air flow moving undisturbed even at high velocities where as the square ports with their really sharp short side radius doesn’t allow the air to make that transition with as much ease. What happens is the boundary layer of air along the port floor can and will separate causing the air to slam into the roof of the port and tumble along the floor of the port when the velocity gets high enough. This is not a good thing in the quest for power as this turbulence is very disruptive to air flow. This why we make that region of the port, the bowl, larger in an effort slow down the air flow to keep that laminar air flow across the port floor. Of course this only happens at very high velocities. Also, all L-series heads starting in 1977 have a slightly smaller intake port volume. What the engineers did was cast one side of the intake port wall with a “flat” in it, “D” shaped if you will. This reduction in cross sectional area starts approx ¾ of an inch into the port. This port shape is supposed to help bias the air flow as it enters the chamber more towards the middle of the combustion chamber itself, steering away from the chamber walls is passes the valve head. In theory this helps to reduce some of the air from slamming into the chamber walls of the combustion chamber. I don’t have enough hard evidence to back up this theory, but I do feel that this port bias does not detract from the performance potential of the cylinder head one bit.
Now we get to the P-79 and P-90 heads. The combustion chambers of these heads are IDEAL, almost perfect once the valves are unshrouded. The only down side I see to the P-series heads, (and this down side is for the extremely radical ragged edge engines, not so much for the milder even hot race engines), is since the chambers are taller, (valves are now shorter as a result), the floors of both the intake and exhaust ports now have an even sharper short side radius and as stated previously, this is a detriment to flow as velocity increases. The transition from the horizontal plane to the vertical plane on the intake and vice versa for the exhaust, is not as smooth as the N-series and E-series heads. Now don’t take this as I am bad mouthing the P-series heads cause I’m not. I really like these heads for hot street and mild to moderate race applications. They are an inexpensive way to get the ideal squish using an OE flat top piston with a compression ratio compatible with pump gas. I have built several and will continue to build the P-90 and P-79 heads for street and mild race Z’s. What I’m saying in regards to the P-series from the stand point of building THE mega extreme N/A performance power house that is at the ragged edge of making useable power over a very narrow yet very high RPM range such as a best of the best N/A drag racing engine, these items should not be overlooked.
Maxima N-47 head. What a darling mild race head this is. For mild to moderate race engines on a budget, using flat top pistons in an L-28, or even opting for pistons with a slight dome for greater than 13:1 compression, this is my go-to head. Just have your machine shop cut out the old intake seats and install the larger seats for the 1.73” or larger valves, have a competent Datsun engine builder/tuner unshroud the valves, blend the exhaust seat into the liner, and “waa laa”, a moderately high compression ratio race engine that will perform rather well up to 8000 RPM with the right cam, induction, and exhaust system. With a set of custom pistons machined so that the dish is directly under the open portion of that gorgeous peanut chamber, this head, in my opinion, makes for the perfect street head or mild race engine that runs pump gas. At the moderate level of race and above, I tend to prefer the N-42 with welded chambers and opened up exhaust ports.
Now for that flow bench info I promised earlier on…
Since a flow bench cannot duplicate the dynamics that are happening within the intake and exhaust tracts while the engine is actually running, i.e. sound pressure waves, pressure surges, exhaust heat, fuel enriched intake charge, valve overlap extraction, etc, flow bench numbers are nothing that should be used for comparing one head to another or bragging how good one thinks their head is! The best way to use flow bench numbers is using the SAME flow bench to compare ONE cylinder head for improvement after modifications have been performed, making note of any changes in air flow whether improvements were made or lost, nothing more. Flow benches do not represent what is actually going on within the intake tract OR the exhaust tract as mention previously, i.e. Dynamic air movement, pulses, waves, heat, etc!!!!. In real life, the valves are opening and closing causing the air to stop and move, stop and move, over and over and being as air has weight and is compressible, this constant surging will cause the pressures to rise and fall FAR above and below ambient. Depending on RPM, runner length, runner cross section, port shape, number of bends in the port and radius of those bends, valve shrouding, air density, cam timing in relation to the piston movement, (this has a HUGE effect on how the air gets moving within the intake and exhaust tracts, hence lopey idles, hard hitting powerbands, etc), there could be higher than ambient pressures at a particular RPM, i.e. a natural supercharging effect, that is why intake and exhaust runner lengths are TUNED! We have all seen where almost all Nascar engine builders have achieved over 110% volumetric efficiency on a naturally aspirated 2 valve engine by tuning the intake AND exhaust tracts to a specific RPM with specific runner cross section and runner lengths. This tuning is taking full advantage of the Helmholtz principle. Your basic garden variety flow benches do NOT and can NOT duplicate this, I’m not even sure if there is a flow bench made that can do this. The only real measure of how good a port can make HP, is to mount that head on an engine and run that engine on a Dyno, (and this is what we are REALLY after right, HP! Not just some arbitrary static flow number through a head port)! An example would be if one head that on one flow bench indicates it will outflow all the others tested, when all are attached to equivalent short blocks, the high flowing head could easily make LESS power on the dyno, but then again change the configuration a little with a different cam, intake tract, piston some shape, etc, the results would get even more confusing.
Ok, I think I’m finished now.

Inhale…… WHEW……..

Thank you all for allowing me to take up so much band width.

Paul (BRRAP) Ruschman
Rusch Motor Sports
__________________
Paul (BRAAP) Ruschman
Rusch Motorsports

[=Enigma=]

Wow! Thanks for all the great insight Paul. I may have some questions for you in the near future as I gather parts for an L28 build up. The block I'll be using for the build is an F54 which will come with a P79.

What's been going through my head recently was whether the Maxima N-47 head off of an W24(2.4L) block was a worthwhile investment for a stage I or II level street performance engine? I have a bead on one or two for a fairly cheap price. Based on what you said here, it sounds like it is.

So, if I had a choice between the Maxima N47/L24 or the N42 and P79 from L28's for my build, what would you recommend?

Also, is there any difference betwen the N42 head found on N42(2.8L) block vs. those found on the Maxima P30(2.4L) block?

[montoya_fan01]

Wow! Thanks for all the great insight Paul. I may have some questions for you in the near future as I gather parts for an L28 build up. The block I'll be using for the build is an F54 which will come with a P79.

What's been going through my head recently was whether the Maxima N-47 head off of an W24(2.4L) block was a worthwhile investment for a stage I or II level street performance engine? I have a bead on one or two for a fairly cheap price. Based on what you said here, it sounds like it is.

So, if I had a choice between the Maxima N47/L24 or the N42 and P79 from L28's for my build, what would you recommend?

Also, is there any difference betwen the N42 head found on N42(2.8L) block vs. those found on the Maxima P30(2.4L) block?

FWIW, I don't think this info was posted on CZCC by Paul Ruschman, I think the poster was referencing info that he found on HybridZ.

[wishihadaz]

Correct,

I am referencing what I read in a L6 forum on HybridZ.
Actually one of two forums on heads.

[=Enigma=]

Whoops, my bad. Good info nonetheless.

[montoya_fan01]

Whoops, my bad. Good info nonetheless.

Absolutely ! !

[Arne]

I may get flamed for saying this, but it seems to me that for most of us - whose cars will not be involved in high level competitive events - all this fuss about which head is better is purely an academic exercise. The difference in performance on a mildly built engine for primarily street use between say, an E31 and a large chamber E88 for example is probably not significant. So for most of us, go with what ever head you've got, or whichever one is in the best condition.

Now, if you are competing at a high level, there is more reason to be concerned. But even then, a 10 HP improvement due to a better head might be compensated for by more skillful driving or better brakes.

[montoya_fan01]

I won't flame you but I submit that even at the lowest level of grassroots competition (street racing for bragging rights, or autocross for example), any potential advantage is worth exploring. A competitor will use all the power (and driver skill) at his command to beat his opponent. If someone is serious about winnig he cannot afford to ignore any potential advantage.

It's true that there is no substitute for driver skill, but an additional 10HP is nothing to sneeze at either.

[280z1975]

I won't flame you but I submit that even at the lowest level of grassroots competition (street racing for bragging rights, or autocross for example), any potential advantage is worth exploring. A competitor will use all the power (and driver skill) at his command to beat his opponent. If someone is serious about winnig he cannot afford to ignore any potential advantage.

It's true that there is no substitute for driver skill, but an additional 10HP is nothing to sneeze at either.

In my life outside of my Z car I compete as a Professinal cyclist where we measure our horsepower in the much small measurement of power, Watts (I put our a MAX instanatinous effort of roughtly 1.5HP when I sprint , but at the pro level it's not that bad.

Street racing and autocross, like cycling, there is a huge degree that can be overcome at the lower levels of competiton through just technic and experince. Where as at the top level just a differeance of as little as .2% can be what wins you an even. I have seen shorter timed evens be lost by .001 of a second!

So as I advise the youngsters that get into the sport, all the flash equipment in the world won't make the differance between winning and loosing. For most people a weekend of driving school or practice will make the differance a weekend of upgrading a head on the engine will make and won't cost them as much in the end. If the driving school won't make you any "beter" and the extra HP is what is keeping you from making the cut at your local autocross event then by all means go for the upgrade.

BTW, I have about DOUBLE invested in my racing bicycle, not including my three other bicycles, than I do in my Z , but then again my bike is my job and my Z is for pleasure. So Arne, your post wasn't that much in vain, it's just up to everyone to decide if that extra money is worth the benifit.

My two cents ...

[montoya_fan01]

but if your competition has been to all of the schools and you have also, AND he's still a better (naturally gifted) driver than you, can you afford to ignore more power? I don't think so, not if you're competing to win.

If the competition doesn't take advantage of everything available to help him win, then perhaps you can afford to do the same, but I say WHY would you want to? Certainly 10HP isn't going to replace driver skill, but if your competitor has BOTH, you had better have them both as well otherwise you're wasting your time competing.

[Arne]

I won't flame you but I submit that even at the lowest level of grassroots competition (street racing for bragging rights, or autocross for example), any potential advantage is worth exploring.

Agreed. But as I said, for most of us - whose pure street cars will never see any track time - I believe the differences between the various heads are minimal.

[240ZMan]

Agreed. But as I said, for most of us - whose pure street cars will never see any track time - I believe the differences between the various heads are minimal.

As a single data point, when I still had my L24 stock motor with 200k miles, I damaged the valves on the stock E88 head. Rather than rebuild it, I picked up an E31 head that had been freshened a few thousand miles earlier, but was otherwise stock. The rest of my engine was stock, except for the pertronix ignition. While I had hoped I'd feel some big difference in power, the reality is that if I was honest with myself, I couldn't feel any difference at all.

Of course, the rings were tired, I used my "butt-o-meter" as my only performance measuring tool, etc. It was not a controlled test at all. But to Arne's point, for a stock motor driven on the street, the choice of head probably makes little difference.

A modified motor on the track, now that's a different story

And lest I give anyone the wrong impression about myself, I've tried dozens (so far) of mods to get that last bit of performance out of my Z. I won't bore you all with everything, many of which others from this site have tried. For me, the chance to participate in all this bench racing, followed by experimenting in my own car, is a big part of why I have my Z and hang around this site.

[280z1975]

but if your competition has been to all of the schools and you have also, AND he's still a better (naturally gifted) driver than you, can you afford to ignore more power? I don't think so, not if you're competing to win.

If the competition doesn't take advantage of everything available to help him win, then perhaps you can afford to do the same, but I say WHY would you want to? Certainly 10HP isn't going to replace driver skill, but if your competitor has BOTH, you had better have them both as well otherwise you're wasting your time competing.

All the points you make are quite valid. At top level I complete at in cycling I look for any way to obtain a better power.

But the point Arne and I are making is that for people who aren't at the top (in cycling you start off at a level 5 in the US, I can't really say what I could equivalent it to for racing of Z's) it would make no sense for them to start off with a top end bike or the best of the best. I suspect for a general perspective of the Z members here 95% of us wouldn't notice or 'need' the change a head would have. For us it would be better placed.

BTW, a common practice in cycling to reap the benefits of your power is efficiently, or dropping weight. It's just my outside view. but if someone who is a weekend racer and wants the benefit of extra power but can't afford I would suggest taking out EVERYTHING (spare tire, passenger seat, etc.) that you don't need. That would make the car run much better and faster.

Ok, back to the point we both agree. If you RACE (serious competition or job) , get all the extra horsepower you can

Still for me a weekender (non-serious completion or fun weekend track racer) would be better off just learning to race. If i ever get into racing cars (who knows, maybe after my cycling career) I wouldn't race my Z, but rather build up another Z or 'race' only car. Cause when I do things, it's never to the half and half perspective .

[Walter Moore]

I could stand to lose a few pounds myself...

But serioiusly, I mentioned to my 300 pound 18 year old son one day that the two of us couldn't ride in the 240Z at the same time because the weight capacity of the car is listed as 420 lbs. His 300+ and my 200+ add to WAY more than 420 lbs...

In go-cart racing this is a major factor, because the minimum weight includes the driver... The less the driver weights, the more cool stuff you can add to the cart!

Some of us would make the car faster if we just went on a diet.

(I am talking about me primarily...)

[montoya_fan01]

But the point Arne and I are making is that for people who aren't at the top (in cycling you start off at a level 5 in the US, I can't really say what I could equivalent it to for racing of Z's) it would make no sense for them to start off with a top end bike or the best of the best. I suspect for a general perspective of the Z members here 95% of us wouldn't notice or 'need' the change a head would have. For us it would be better placed.

Neither side of things should exclude the other IMO. Driving Schools (the good ones) aren't cheap either, and it is easier to learn to drive faster in a car that performs consistantly well than in one that consistantly doesn't.

One thing that none of us has mentioned is that some people just love to work on their cars and regardless of any possible performance advantages, they just "want" to tinker and make their car better in their own eyes.


"Different stokes for different folks." "Somebody has to win, and somebody else has to lose."

"Focker OUT!"

[280z1975]

snip ....

"Different stokes for different folks." "Somebody has to win, and somebody else has to lose."

"Focker OUT!"

Well said .... two of my favorite quotes

"It matters not whether you win or lose;
what matters is whether I win or lose."

"Adapt, Improvise, Overcome"

[montoya_fan01]

Well said .... two of my favorite quotes

"It matters not whether you win or lose;
what matters is whether I win or lose."

"Adapt, Improvise, Overcome"

Yeah those are favorites of mine too.

[=Enigma=]

No matter what I am buying, I will always research ALL the options myself before making a decision. In my case, I happen to have a line on several different heads so I want to make sure I purchase the right one(s) for my goals in the present, and possibly for the future as well.

[John Coffey]

Back when I was Category 4 (Crash 4) bicycle racer, it was always fun on training rides to pass riders on De Rosa's, Lightspeeds, Kestrel's, etc. while riding my ugly green and white Centurion Ironman. I would always say, "Nice bike!" as I went by.

Same is true racing 240Zs. At the Z National track event at WSIR back in 2004 the Rusty Old Datsun was faster then the Grand Am 350Zs, even with Art Singer from Sport Z as a passenger. After one of the sessions the owner of the two 350Zs came over to look at the ROD and when he saw it was a NA L6 he said, "Man, I would have sworn you were running a turbo."

There is some satisfaction to be gained by being succesful with equipment that everyone else says is junk.