I believe there was a post addressing something about this before, but I was wondering if someone could just clarify for me. The L24 puts out about 150 hp, and the L26 puts out about 139 hp? The 240z tech webpage has an engine spec section where they list the L26 as having 162 or so hp. Is that the engines potential base hp? As in with all the smog pump things removed? I've been told the emission laws cracked down on the 260z's at the time, so would an L26 be close to that 162 hp figure if I used SU carbs from a 71 240z? I've got a L26 I was thinking about restoring, so when I saw 162 hp I thought that might be a sweet deal, but I've also seen that lesser 139 figure... Could someone clarify? Any input would be greatly appreciated! Thanks!

http://www.240z.org/forums/showthread.php?s=&threadid=1744&highlight=BHP

Does that mean the GROSS HP for a l24 is 150? And if the gross HP for a l26 is 139, how is that if it has more displacement? Would those non-emission carbs help?

Gross hp ratings are 150 for the L-24, 162 for the L-26 and 170 for the L-28.

These are factory advertised gross hp ratings. The net is what you can expect in the real world. A lot of manufacturers would advertise gross hp ratings that were unrealistically inflated to sell cars, then left it to the buyers to find out they didn't get what they paid for.

That is the main reason all hp ratings are now given in net hp ratings. It is a more realistic rating of the true hp of the engine.

Net hp ratings are more along the lines of what you could expect the engine to produce on a dyno at the crankshaft, not the rear wheels. A manufacturer might take a test group from the production line and dyno them, then publish the results.

So if the net hp rating of an L-26 is 139, then the L-24 would be about 127 and the L-28 nearer to 147. Not sure of the exact numbers.

The only correct way to judge an engines true output is to build it and dyno it. No matter what, one engine will not be the exact same as another especially if it was built in a mass production. Hand built engines of equal parts may produce equal results but even then you will slight variations.

In that topic I posted, stock-z said "I've seen elsewhere the 260z having 139 and the 280z having 149", so they're probably the correct gross BHP figures.

Thanks for the info guys. I'm guessing it would be a lot more worth my money to try and rebuild a L28 then my L26 I've got in my garage then? I'm trying to give my 260z some power since it's heavier then the 240z.

It certainly would. Either that or find yourself a nice Skyline engine

Before turbocharging my R30 Skyline, I had dyno runs done with both the L24E & L28E motors.

The runs were done on a Dyno-Dynamics rolling-road dyno. The drive train in my car was as follows:

3N71B transmission, in 2nd gear

3.90 R180

195x60x15 tyres

L24E - 62kW

L28E - 68kW

The L28E had more torque, & the L24E peaked in HP higher in the rpms.

The L28ET was 125kW....

I will shortly be doing another run with a standard FJ20DET, so we'll see how that compares.