In some cases the rear wheel HP could be lower by as much as 40% to 60% compared to crank dyno results

 

:iagree: try to find someone with a 650 dp that you can swap with for a few runs, I have a 750 mech dp on my 383 stroker and would not want to go any bigger.

 

:iagree:

and those heads look like a zz4 head to me! that guy was wrong!


[Modified by QuickVet, 7:34 PM 9/23/2003]

 

So you guys are basically telling me that my ZZ4 that will keep up with a 310 RWHP 13.5 second Camaro SS (Dyno proven before he moded it and got into the 12's) and I could be losing up to 50%:eek: through my drivetrain/accessories. I don't believe it. :nonod: I know my old technology is not a efficient as a new Camaro but I know I have to be putting down at least 300 HP to the ground. I need to get mine on a dyno. The only accessories I am driving are the water pump and alternator. Muncie 4 speed also.

 

I think most folks would be surprised on a REAL rear wheel dyno.
Last Sat. a group of C2 owners (small club) ran about 25-30 cars on a
rear wheel dyno. Most stock C2 small blocks were in the 230 to 260 range
RWHP (rated from 300hp to 375 by GM)., and stock BB's were in the 265 to 300 range with Toruqe in the 325 to 350 area. (GM rated hp from 390 to 425.)
Again, these are street driven stock cars. The type you see at most vette shows. (mine not included :D )
A modified 91 ZR1 (head work, chip, exhaust, air intake, had 370 rwhp, and a built 67 (ground pounding) 468 came in at 380 RWHP.
I have my timing retarded to run on 91 pump gas, and hit 300.3 at 5750,
and 325 RWTQ at 3800. Wished they would have ran it to 6500 as it was still climbing, but it was only $40.00 for 2 quick pulls with no time to adj. or advise, In and out in a minute or two. The good news is, it helps you fine tune your car. I plan on improving my side pipe set up, and adj the timing,
some tuning, and run some real gas next time. 102 or so...... And think an additional 50hp will come pretty easily.
It was an education. And have a new appreciation for cars putting out
400-500+ real RWHP. And dont believe everything I see posted anylonger. Its the real deal. Anything else is just bench racing.
:cheers:

 

What you say is true I have never seen anyone happy with their first pull on a chassis dyno, it is a humbling experience for most with all the huge HP numbers that peope float around, they don't mean anything unless you actually dyno it.

Just a side note I have seen a few ZZ4's run on an engine dyno and if tuned properly ( with a Holley ) they seem to run in the 240 - 260 RWHP range.


[Modified by MotorHead, 7:27 PM 9/23/2003]

 

You would be shocked at how much RWHP you can free up by going to a free-flow exhaust and recurving your dist. I gained 18 RWHP by rejetting the carb and recurving the dist. I can't say exactly how much I gained by switching exhaust because I also moved to a different elevation in between the swap. My 79 now puts down 230 RWHP and 305 lb/ft. torque. I plan on upping that in the next couple years, but I want to modify suspension and brakes first.

Bottom line, your timing can really make a difference, so it's quite possible that you're where you should be at this point.

 

Both the ZZ3 and ZZ4 have the 'center bolt' valve covers.

My warmed-over L48 block (see signature) is producing about 222.5hp/288.4torque at the rear wheels. Assuming 30% losses in the drivetrain, that's a healthy SAE net 318hp/412torque. That's with a 700R4 auto trans. I'm a happy camper :steering:

You can probably extract additional hp/torque with further timing adjustments, carb rebuild/tuning or cam replacement depending on what you have.


[Modified by TedH, 10:09 PM 9/23/2003]

 

I noted in the engine picture that you appear to be running the standard silicone suppression wires. A good set of Taylor Spiro pro wires with good separators are much better and more durable than the stock 8mm suppression wires.

 

I gotta ask: what is the loss with an overdrive trans??4L60 or 700r4??--i got the 400 now ?? Thanks --Glenn :banghead: :banghead: :auto:

 

:iagree: I ran my stock exhaust (y pipes no cat) with the ZZ4 of the 1st year and must admit, i was disappointed with the performance, finally saved enough for the sidepipes and STS baffles and it is a VERY noticable difference. Also curved dist to 'all in' @ 2600 and have been all :D since. Hope to get on a dyno soon and would be happy with the 240-260 mentioned.

 

Yep. I agree. Before these chassis dynomometers became popular everyone would just throw out a #. I know that on the "ringer" cars (like the L88, for instance) power was intentionally underrated, but for most of these cars the "gross HP" #s are so high, that what you get to the ground ends up seeming very low.

I see all these posts with guys who claim they have 400+hp cars that run mid-13s or slower.

It is truly bench-racing at its finest. The dyno, just like the track, doesn't lie. ;)