My dissapointing dyno day


Jan 31, 2005
took the car up to a local and well known dyno shop around my part of town and put down 321hp and 301tq. The a/f was running 13.9 after we adjusted it on the 2nd run and did the same on the last run. we could not do any more pulls because it kept running rich and the way the curve of the a/f kept going. the curve went 10.1 at the begging of WOT and then ended up around 13.9. the tech had to let out of it about 4500-5000 rpm because the a/f kept leaning out. I know the car had more in it but the tech said there was no way to really adjust the a/f at the top end with just a regulator without running super rich at the begining of WOT. So what would the best thing for me to do to get more power out of my car. Should I go with a stand alone managment system? Any info is really appreciated.

more info:
The car was running 24psi (says the tech) with turbo tweak 93 octane chip. fuel pressure was about 46 with line off.

Set up:
I have a Te63-1 turbo, walbro 340 w/hot wire, th350 trans, b&m 3500 stall 202/202 cam, 75# injectors, modified ecu, accufab AFPR, PTE front mount, scan master, atr 3'' dual exahust, gutted cat, atr 3" dp.

follow the link to the pictures
Not to change the do you like that B&M tc with your TH350. I'm having one built and am unsure about torque convertors.
8AV8 said:
Not to change the do you like that B&M tc with your TH350. I'm having one built and am unsure about torque convertors.

I love it, hav no complaints
It looks to me like you're running way out of fuel. If your sig is correct, and you only have 1 pump, that is definitely your problem. Get yourself a double pumper (Red's XP plus double pumpers).
Make sure you are running the car within the design parameters of your chip. The chip has a boost level written on it. For 93 octane, it should be about 18psi-20psi for your combo. Once you're in that range, then see what it does for a/f ratio, although track tuning usually tells a better story. The chip can be adjusted to your combo.

If you want the dyno guy to tune your car, then an aftermarket system they are familiar with would be best.

Somethings not right here, 75lbers and a TE63 should have plenty of injector left, what was the Duty Cycle?

You are not pushing it if the cars only getting 300/300, no way you are out of fuel at that power level on 75's, and no way thats 24psi on a TE63.

If the car was running lean even at 4500-5000, you should of already hit your max TQ and HP and your HP numbers are about a stocker with an exhaust system, chip and cone.

Of course you can always get Eric to Tweak the chip for you up top but you can also get a translator to add more pulsewidth.

What scanning tools do you have?
IMO, there's no reason to go to aftermarket engine management at this point. My suggestion is to go back to the basics. The fact is, there's no way that 1 fuel pump is going to feed enough fuel to 75lb injectors at 24lbs of boost with that size turbo. Did you verify your fuel pressure @ wot while on the dyno?
I had a similar problem with my stock long block GN. I had to set the fuel pressure at 55lbs with the line off just to keep from leaning out on the big end. This was with a TA49, 009 inj, and a poston replacement fuel pump. I swapped out the pump for an XP plus, and it cured it.
Here's a start. First, be sure your throttle blade is opening fully and the TPS is going over 4v. Be certain your regulator is set for the correct static pressure (line off) as dictated by your chip. Next, put a gauge on the fuel rail, disconnect the vacuum line going to the regulator and connect it to a hand-held vacuum pump like a "Mighty-Vac". Note the reading changes under vacuum (should decrease 1# per 2" vac). Now switch the Mighty-Vac over to the pressure side and do the same. Note the reading changes under pressure (should increase 1# per 1#). This will insure your regulator is working at idle. Best thing to do next is temporarily connect the gauge with a length of hose and tape it to the windshield. Now go for a ride and make sure it works under driving conditions.