these are my mods 10.1 comp forged bottom end twisted wedge cylinder heads'1.5 rr ,compcam 12-246-3 gross valve lift.48.490 ,duration at .050 intake 230 exhaust 236 , lobe lift.3250 intake , .3270 exhaust lobe seperation 110.0, headers ,hsr, 33lbs injectors, haltech e6gm, walbro 255ltr fuel pump, t700 2500 stall. all this and i could only scavenge 240 rear wheel hp any suggestions?alot of people that i have spoken to seem surprised that i couldnt get at least in the 300 rear wheel hp with this setup

 

how well is it tuned?

 

who cares about dyno numbers what does it run in the quarter .

 

Right, either the tune or the dyno. I have a very similiar setup but with a much smaller cam in the ZZ9. I'm putting down 283RWHP and if it was a manual transmission it would be 300RWHP. I'm tweaking some more and hope for the magical 300RWHP with my 700R4.

What intake system are you running? Stock TPI?

One thing you did not mention was the intake system from the airfilter to the throttle body. The firebird system is not good for performance. You need a custom cold air intake. A friend picked up 16 horsepower with this mod alone. I have one on my car.

You also did not mention the exhaust system past the headers. You need an aftermarket "Y" pipe and 3 inch from the cat(s) to the muffler. Mandrel bent of course. If dual cats 2 1/2 inch from the headers to the cats. Allen

 

You have a HSR, right?
That thing must be a bitch to tune. Thats a big cam with a tight LSA. Plus you have really big injectors.
I suggest u find someone in your area to spend a lot of time with your tune, cuz i think with that setup, your going to need someone with experience.

 

What 1989GTA said. I put down 330 rwhp @ 5850 rpm with a similar combination on a DynoJet running a 218/228 - 110 cam, 24# injectors, single 3" exhaust, and the stock ECM and chip (adjusted fuel pressure). As lean as mine was running, I know there was 8 - 10 more horses in it at peak.

Something is off, engine or tune for sure. Did you get an O2 reading at the dyno? Was this a Mustang dyno? They typically read lower than a DynoJet,, if not, you're at least 100 horses off where you should be. Should be easy to tune with the Haltech though.

 

33 lb. injectors? I'd bet your'e running too rich if your'e using a stock chip.

 

Whats was the AFR like? Dont get to caught up in the tuning if something mechanical is not right.

Thats what happened to me. Spent alot of time trying to tune a broken engine. My car only put down 306 rwh and 419 rwt the first time out. I had to cylinders sucking water thru missed drilled steam holes. Car detonted like crazy, Lots of other little things that killed power.

 

What kind of torque did it produce? I had my car dynoed and saw 310 hp. I about puked. Then I noticed it made 390 ft lbs at the wheels. Car ran 12.02 in the 1/4 with this combo. Torque is key for a heavier car.

 

I agree!

 

the exhaust side of things is covered its all custom made from scratch from a reputable exhaust shop the tune also was performed from one of the best if not the best here in Australia it idles and drives better than stock with the haltech i just was expecting higher hp. the only thing i should do is buy a set of grippy rear tyres and take it to the trackand see what 1/4 times it does one thing i noticed the other day is the butterflies from the throttle body are not opening all the way im losing a 1/4 throttle would that make a difference?

 

Well I would suggest you tune is way off. Those injectors are WAY too big also. What kind of A/F numbers did they record on the dyno?

 

could you clarify what a/f numbers mean? also if the injectors were to big wouldnt the car run rich?I PULLED OUT A SPARK PLUG AND It was white all over wouldnt it be black or black smoke coming out of the muffler?

 

A/F ratio = Air:Fuel ratio, and yea, if your plugs look good and it runs good at low loads your haltech must know what size injectors its firing. If your throttle linkage is not opening the throttle body all the way I would start there, then take it to the track and see what kind of mph (or kph?) you get.

 

You need for the throttle body to go to wide open. 3/4 of the way is hurting your airflow. So yes that is part of the problem. Allen

 

i wiill definately look into adjusting the throttle cable and make a spacer for the throttle body as the throttle linkage is too close to the fuel rail after the hsr swap also i know the topic of larger throttle bodies have been brought up any opinions with my setup would a 58mm make a difference? thank for all your replys

 

My 383 9.8:1 with a crane hyd roller 230/238 AFR 195 heads, Holley stealthram made 358rwhp and 396rwt. I have 36lb injectors and 58mm tb. try tb and more tuning.

 

I have a very similar set up as BadSS's. 10:1 compression on ported heads, 221/221@0.050 Iskendarian cam, ported upper and base plenum, Hooker headers and a true dual exhaust.
This car is STRONG, although I've never run it on a chassis dyno. I have not changed the prom, I'm sure it's got more potential, but jeeze, $400 clams for a prom???

Anyway, I have an idea that I think you are trying to run too much cam and you have a mismatch. The tuned port is a good torque-building system, but it has limitations on rpm. About the most it'll pull to with a well-matched cam is a little over 5000 rpm. You'll get a little more if you get large runners. But don't bother with a 58 mm throttle body if you haven't enlarged every single thing on the way to the cylinder. Alone, that wouldn't do you any good.

A good exhaust is key. If you're running stock exhaust, I wouldn't be surprised if you're losing 30 to 40 hp right there alone. But it sounds like you got a decent exhaust built.

No, I think your main problem is that you are trying to run a cam that wants a powerband more like 2800 rpm to 6500 rpm, and you've got an intake that will only allow idle to 5200 rpm...ported.

Two ideas that will help you. Either back off on your cam and get one that matches the rpm band of your tuned port manifold, or keep your cam and exchange your tuned port for a Holley Stealth Ram, which will use your same harness, computer and injectors.
I'd probably go for the latter, it would be an easier swap, and the stealth ram is not that expensive, by itself without any of the electronics.

If you do stick with TPI...make sure to grind down the restriction in the flow path right behind the throttlebody.

 

He has a HSR.

 

and a cutom exhaust

 

Two questions:

1. What is "HSR"?
2. My quote, "But it sounds like you got a decent exhaust built.", seems to indicate that I am acknowledging he has a custom exhaust. Do you think these two things alone should make his car stronger than 240 hp?

Just trying to help.

 

HSR is the Holley Stealth Ram intake manifold.

www.stealthram.com has a bunch of info about it.