cross ram intakes

[Gray Ghost]

Here is a stock 290 horse car....results were read from a dyno according to this page here and the single 4bbl version got 400 hp. Add in the crossram, cam and headers and you can easily see it could pull 458 on the dyno.

http://musclecars.howstuffworks.com/...camaro-z28.htm

Don't dyno numbers mean rear wheel HP?

I am not upset in the least. I got confused in my old age about the numbers, it happens. That said all the results I have ever read from the Crossram numbers were from dynos. If you can find anything that says otherwise on the subject, I will stand corrected twice.

PS....just dawned on me....what would 458hp at the rear wheels be at the crank? Maybe I had the location of the number wrong. Food for thought.

Back to the original subject, they were a bear to tune and only good at very high RPMs...not good for the street by any means.

[71Dragtruck]

458hp at the rear wheels is around 558 at the crank, 100hp loss through the drivetrain is kinda an average and alot of other factors can effect this number. You also loose less power through a standard tranny then a auto so 100 is just a average alot use could be more or less. Only way to really tell is dyno the motor on a engine dyno then put it in the vehicle and run it on a wheel dyno ( like a engine dyno but instead of attaching to the crank, have large rollers that you spin with the drive wheels to messure HP ) and see what your accessories and drivetrain use up on you.

But ya anyway back to the original post, sorry for the detour.

No doubt only good at high RPM's, just read that last link posted, it states that even dropping the clutch at 4000rpm's produced a stumble in the 302 Z28, can't see that problem beeing any better with a 350 in a heavy truck with a auto tranny.

[larry may]

Even before 1967 chevy was known to underate their HP. Do like your information.

Originally Posted by Gray Ghost

Chime as you will. I saw the test myself back in the 70's and have heard about that same test from two other sources on the Horsepower TV shows. The Z/28's 302 was the Trans Am series homologation motor and was well known to be more powerful than the specs. It is a well known fact that GM and all other manufacturers lied about HP after 1967 to hold insurance rates down as well as to get hot cars by the fed's new smog regs.....also the two main reasons that manufacturers went to net HP figures in 1971.

That doesn't mean every Z28 from the factory had that much power. That said, not one ever dynoed at less than 350 hp that I ever saw. This one had two 600 cfm Holleys on the crossram manifold, headers and aftermarket mufflers and ran low 13's in the 1/4. The tranny was an M-22 rock crusher IIRC.

Your doubts have me curious as to whether I can find it in print...hopefully I can post a link later.