Best pull on dynojet was 296.78 hp, 317.83 tq. I've seen others in the forums claim 320-330 rwhp is attainable with this setup. I'm assuming my dynojet numbers are at the wheels, and not the flywheel, right (that's what the tech told me but it doesn't explicitly state that on the print out and I just want to be sure). If these numbers sound about right at the wheels, what is a general drivetrain % loss with all stock accessories & manual tranny so that I can calculate the power @ the crank? No A/F info was provided.

 

I'm not sure on the numbers themselves although I suspect they're low. I generated 300 hp at the wheels with a stock cam using roller rockers, hypertech tune, electric waterpump, an SLP CAI and stock exhaust manifolds with large diameter y-pipe and Corsa Catback. It's very likely there is more in there with an updated tune. The AF measurements will help the tuner set it up...

If you drove your car to the shop and onto some rollers, you measured rear wheel horsepower. A M6 car typically loses about 15% of it's power through the parasitic loses of the accessories and gearsets. Losses with the automatics are greater, to the tune of about 20%

 

278rwhp 320rwtq for my car in my sig

 

These dyno numbers are after the mail order tune for the cam. I guess I should just get dynoed with a/f readings to see if I'm where I should be. The power starts to level off around 5500rpm, and I was under the assumption that cc503 will make power til 6k+. valve float issues?

 

sounds like you have a stock cam lol. Did you build your engine?

 

yes. I put the cam, springs, & rockers in myself...parts directly from summit. car seems to run completely fine. I just am unsure about the lower than expected #'s.

 

could be too tight of lash, or cam not degree'd properly. If your losing power early, it sounds like it is too far advanced.

Altho, dyno's are just a tuning tool, how's it run at the track?

 

i've adjusted and re-adjusted my valve lash several times. 5/8 pre-load on my stockers shouldn't be too much, right? i do have my stock 24# injectors in though...do you guys think that could be causing my drop off after 5500? never ran it at the track by the way.

 

1/4 to 1/2 is plenty of pre-load. I'd reset 'em and see if that helps. The 24 pound injectors can work...it depends on the target horsepower. You need 1/2 pound of fuel per horsepower per hour on an engine of normal efficiency. The tuner would have told you you have too small an injector....

 

ok...tested fuel pressure...here are my findings

35 psi with key turned on only, drops to 30 psi after 15-20 mins
with car on and idling, 35-37 psi
with car on and idling & fpr vac line removed 43psi
with car in neutral, slowly revving to 5500+ rpm (I would figure this could simulate real driving wot conditions), pressure drops from 35-37 to 31-32 psi, never increases with rpms
no fuel leaks from the vac line at the fuel pressure regulator
I know the factory specs call for 41-47 psi with the key turned on (primed), and mine is 35. also, what's the deal with my vac line wot psi (43psi) vs. wot under load (31-32 psi) discrepancy?

Does this sound like a fuel pump issue?

 

Should be more like 40 with key on.

Bone stock motor with Longtubes and 3 inch SLP exhaust I got 271 to the wheels.

 

Mods in sig put down 290whp/325 tq. so there is something wrong with yours.

 

Mine didn't have a WOT tune fully done and a bad fuel pump that was going to 20psi at WOT and not giving the engine all the fuel it wanted and I had 321hp with cutout closed and 325hp with the cutout open.

A4, CC503, 1.6 pro mag roller rockers, 30# fuel injectors, ls7 lifters, 918 springs, etc, etc.

But my AFR was 14.7... (bad fuel pump) Haven't had it dynoed since the fuel pump was replaced and the tune was completely finished.

 

1994 Z28. LT1 M6
K&N CAI - small power adder
TB bypass - no power adder
vortec elbow - no power adder
cc503 - big power adder
comp pro mag 1.6 rr's - small power adder
crane dual valve springs - small power adder
JBA shorty headers - medium power adder
muffler delete - ?? no muffler at all? Cats?
LT4 km - no power adder
melling 10554 ???
Eibach sportline springs - no power adder
madz28 tune - this can go both ways here.
3" cowl hood - no power adder


For a bone stock Z I would say you started out at 250ish rwhp. I think 46rwhp is on par with what your mods are.

Most people do all the bolt on stuff.. Electric water pump and such..

Not all cars are created equal.
I was putting down numbers like yours in a 1995 Auto Z28 with just bolt ons.

 

Updated fuel pressure test:
35 psi key on, engine off
engine idling ~33 psi
engine idling, fpr vac line removed ~41 psi
revving motor with steady pressure up to wot in neutral ~30 psi
driving motor to wot down the road several times ~39-40 psi consistently
driving lightly around town for about 15 mins stop & go ~32-34 depending on rpms
after engine is cut off, psi drops initially to around 29psi and holds for a significant time, I'd say at least 10 mins or so
no wetness or smell of fuel on fpr vac line
fuel filter has less than 15 k on it

Does the pump seem like it could be the culprit?

Anyone know of any dynotuners in nor-cal? I need to get this reslolved.