Why does an L28 make less HP than a L24?

[SFART]

Hello all. I am new to this forum and I have decided to start off my first entry (question) with what i feel is a very rookie question--

Why does an L28 make less HP than a L24?

To my understanding, the fuel-injected L28 makes less HP because of "an increase in smog emissions requirements(back in '74)." So, I assummed that removing all of the egr and smog stuff would make for an immediate HP gain. But, I read that this in fact does not icrease HP and could even lead to a decrease in HP. Any info relating to this would be greatly appreciated since the answer to this question has evaded me for so long.

BTW, I currently do not own a Z, but I am planning on purchasing one soon.
Specifically, I am planning on swapping a 280xt engine into an early Z. Still looking for the right one!

[GunnerRob]

Hello all. I am new to this forum and I have decided to start off my first entry (question) with what i feel is a very rookie question--

Why does an L28 make less HP than a L24?

To my understanding, the fuel-injected L28 makes less HP because of "an increase in smog emissions requirements(back in '74)." So, I assummed that removing all of the egr and smog stuff would make for an immediate HP gain. But, I read that this in fact does not icrease HP and could even lead to a decrease in HP. Any info relating to this would be greatly appreciated since the answer to this question has evaded me for so long.

BTW, I currently do not own a Z, but I am planning on purchasing one soon.
Specifically, I am planning on swapping a 280xt engine into an early Z. Still looking for the right one!

Welcome to the club, Art.

I think you may be confusing accelleration times with HP. The 240Z (L24) is quicker due to the pounds/HP ratio advantage compared to the 280Z's (L28).
The L24 in the 240Z is rated at 151 HP at the flywheel, while the L28 in my '75 280Z is rated at 170 HP at the flywheel. So, if you put the entire 280Z engine, including all of the original intake components and engine control unit, into a 240Z, you'd have a quicker (170 HP) 240Z!

A significant number of members here have swapped in L28 blocks into their 240Z's because they wanted the additional HP and torque gains associated with the increase in displacement.

[texasz]

The L24 in the 240Z is rated at 151 HP at the flywheel, while the L28 in my '75 280Z is rated at 170 HP at the flywheel.

I believe that those numbers are at the rear wheel...I think that the 240Z has 170HP at the flywheel IIRC.

[240ZX]

I believe that those numbers are at the rear wheel...I think that the 240Z has 170HP at the flywheel IIRC.

It's at the flywheel....151 HP for the 240Z & 170 HP for the 280Z. To date, I don't think any auto manufacture lists RWHP. A trip to a local dyno shop will take care of that issue!

[beandip]

[QUOTE=SFART]Hello all. I am new to this forum and I have decided to start off my first entry (question) with what i feel is a very rookie question--

Why does an L28 make less HP than a L24?

The engines were tested differently back then and the numbers were misleading . The figures reflected in the later years are more correct.

[thehelix112]

One is DIN, one is SAE I believe.

Dave