Had the car dynoed today, seems like i got really low numbers for my mods...run 2 was made with the serpentine belt taken off...therefore you should look at the first run

with what i have done i though i should be in teh 350-360hp range...?

http://www.bmcomputersource.com/domdyno1.bmp


mods include:
complete rebuild 5k miles ago
.029" impala head gasket to raise compression to 11:1
heads fully ported and portmatched locally, stock valves (no flow numbers on the heads)
224/230 .536/.544 112lsa cam
Hooker long tube headers, off road y pipe, flowmaster exhuast
Spec stage III clutch with spec aluminum flywheel
Tuned locally
Stock throttle body & injectors...

Any ideas on what could be holding me back? The stock throttle body maybe? I don't know the duty cycle on teh injectors but if they would be maxed out i would think the car would be running a lot leaner than it is.... what do you think about the a/f ratio?

Also, the knock sensor is zeroed out therefore i know the knock sensor is not pulling any timing...

Dyno numbers are SAE corrected...

 

probably not the TB....i dont think that becomes an issue until over 400.

id guess its the heads. you cant expect too much with stock size valves.

 

I would be happy with 350rwhp if I didn't know what my heads flowed.

 

Keep in mind that the 350hp run was with no serpentine belt. I will have flow numbers on the heads next week. I would guess that they are in the 260's range...

 

OUCH...thats pretty hurtin.


i think youd dyno a lot more if they really flowed 260cfm.


did bob have any suggestions as to whats causing it?

 

Don't worry about dyno numbers. They are used for bragging rights and comparisons. What you have will show up in performance.JMHO

 

Well, that's were trying to figure out. So far to me it seems like its running a little lean, and i think the injectors are maxed out. I'm also interested to see what the heads will flow, but i don't think that the heads are the problem.

 

well i know people that are maxing the injectors are hitting higher numbers..........so maybe just the injectors arent functiong right............is your fuel pump maintaining constant fuel pressure? that could also be a prob, if fuel pressure is dropping at the top end from a dying pump.

 

I sold my fuel pressure gauge last month, but as of last month it was running at about 43psi at wot...

 

What about your converter? I know my numbers were lower the last time I got mine dynoed and they said that converters "kill these cars on the dyno".

 

 

maybe its not strong enough for the new setup tho.

 

The heads are probably not the problem. Two examples:

My last NA combo: Crane 210/224 cam, Ported heads @ 225 cfm intake max, stock bottom end, stock intake, AS&M headers, automatic. 340 rwhp

SAR2K: "Large" super-secret custom grind cam, Home ported heads @ ~255 cfm max with stock valves, stock bottom end, Hooker LT headers, automatic. 451 rwhp. Yes, 451 rwhp NA stock bottom end.

The A/F ratio looks lean throughout the curve. It should be at 12.5 or so. If the injectors were maxed, it would only be lean on top end. Try increasing the values in the PE table. Your tuner should easily be able to do this.

Do you have all the bolt-on's? TB airfoil? CAI? Underdrive pullies?

Mike

 

well he dyno'ed with the belt off.........so the pullies wouldnt make a difference.

i doubt the airfoil is really worth much either....do you think?

 

i doubt the pump is too weak if its holding up 43psi at wot all the way up to 6,300 and fuel psi doesn't drop. how would i tell if its weak?

i don't have the tb airfoil mod, and i have a stock under drive pulley.

I'll take it back to the dyno hopefully next week with bigger injectors and some more tuning... Hoping for better numbers