Here are the rules. Engine no bigger than 360 cubic inches. Must be an L98. Must have EFI and no carburetor. Must be naturally asperated. NO blowers or NOS. Reason I'm asking is that on the LT1 boards and LSx boards there are plenty of cars with 400rwhp. Can't say I have seen it with an L98 with in the rules.

With all the good heads and cams out there nowadays it should be attainable. I know Vincent Z28 is at the 373HP mark and his car is capable of some more horsepower. So who has one?

 

I'm sure there's at least one out there, but it's just a little harder with our cars since we don't have the modern technology behind us. All the LT/LS guys hate thirdgens but they don't realize that they wouldn't be where they are without L98's Not to mention that from the firewall back the cars are nearly identical.

FWIW there was a guy here a few months back claiming a stock 90k mile bottom end with Vortec's, SDPC base, 236/242 cam, 2400 stall, stock 700R4 and 3.73s claiming 420hp and running 11.90's. Not sure where he went but haven't seen him in a while.

 

I'll be sitting at about 500 flywheel hp when my 383 is done (according to many VERY simmilar builds in magazines) so we'll see how much of that gets to the rear wheels. I have a Cutlass with a Olds 350 that put out 420 at the rear wheels, but that's an Olds engine (ie better). Oh and all my engine builds are carburated- mostly cause its cheaper.

 

Its alot harder to make 400hp on these engines then you think. Especially since we have a long tube runner system. a 400hp rearwrhp car would have 600-700ft lbs. of torque. Keep in mind the stock TPI system even the ones in the vettes was designed for the 305 not the 350, the 350 engines hit a brickwall with the stock system around 4800rpm. The runners can not supply the air, if they upgrade the parts list is still very limited, but it is actually easier to get a 305 TPI to go faster than a 350 TPI... Reasoning is torque and air requirements. Keep in mind that a 350hp L98 should outrun a 400hp LT1... As long as it can get traction.

 

One of the guys I work with has one of those TPIS (Tuned Port Induction Specialties) catalogs that goes into detail about all the dyno charts and stuff that they have for thier products. I want to say that they had a 350 with thier TPIS Big Mouth base plate and runner system with a bigger camshaft, special ECM calibration, worked over heads, and big bore throttle body pushing out somewhere around the 500HP mark N/A. Now I'm not sure what that would equate to at the rear wheels assuming drivetrain losses, but that's pretty close. To get to that route you'd probalby have to spin the motor up pretty high the make the HP at the wheels OR you can build the engine for major torque. If you can get your torque up to the 500 ft. lbs. level at say 5200 RPM, then your HP will be the same at that RPM because...

Torque x RPM = Horsepower
5252

And as we know the key to build torque is port velocity. Just have to play around with different camshaft and cylinder head specs to get what you want.

 

From the reply's it looks like very very few cars with a 350-360ci motor are making 400RWHP with the L98. Torque though is higher than the corresponding LT1 and LS1's. With my next round of mods it looks like the high 300'srwhp will be it horsepower wise.

I think Vincent Z28 has a good chance to do it. With better flowing heads, custom cam, higher compression, improvements to his exhaust and more tuning I think he can do it. Like I said above he is at the 373rwhp mark with only 27 to go.