Nitrous on a junkyard 3.1

[theoldshedsquad]

Hi, I'm a newbie to this forum and live in merrie olde England (which ain't that merry - it's the European FIA Drag Racing finals here this weekend and it's done nothing but rain for a week).
Anyway, I have a 1990 Pontiac Grand Prix 3.1 LE. It's a real beater, but due to the lack of a "proper" race car at the moment I am racing it in the National Street Car Challenge (see www.hotrodgazette.com if you're interested!). The finals are coming up next month ...
This GP is never going to pass its next MoT (annual roadworthiness certificate/test) in January so I've stripped it out and it's going to race in our finals next month ... and it doesn't really matter if I kill it.
Best time so far has been a 17.5 ... not good enough. It's going to get nitroused. I've borrowed a fogger nozzle, I already have an old Sniper kit (with a plate). Does anyone know of an easy way to retard the timing on one of these motors?
Please note: A) I intend to spend NO money on this car if I can help it. B) I live probably 3000 miles from the nearest junkyard with another Grand Prix in it. C) the motor is all but standard
Love the site, would appreciate any help you can offer!
Dave

[1988GTU]

You could trick the IAT to thinking it's running hotter intake temps than usual. Just need a resistor or locate it in a really hot area.
Is the kit a wet kit? If so, good. Run some higher octane and use an adjustable fpr to set it up half ass wise. Go for the gusto and spray a 150 shot. Might get a few fun runs out of it.

[theoldshedsquad]

Yes, it's a wet kit - the NOS budget job which comes with a plate spray-bay, as usually seen under a four-barrel carb on a V8. I'm going to cobble the solenoids to a Fogger in the throttle body area. And yes, I have 150bhp jets...
Doubt I'll get more than one run out of it at that, though ...

[Ortie666]

run 20w50 motor oil, make sure its tuned on the rich side, and u will get several 150hp runs. probably more than the bottle will hold, ive ran up to 180 shot, on a stock internal iron head 2.8L

[theoldshedsquad]

How do you tweak it to run richer? Will putting a resistor in the IAT circuit retard the ignition timing? I'm guessing around 200 ohms would make it think it was really hot. And the IAT is the little sensor in the air filter housing, isn't it?

[pocket-rocket]

How do you tweak it to run richer? Will putting a resistor in the IAT circuit retard the ignition timing? I'm guessing around 200 ohms would make it think it was really hot. And the IAT is the little sensor in the air filter housing, isn't it?

Adjustable FPR? And yes, the IAT is the little sensor with 2 wires in the air filter housing. As for the resistance value, I have no idea, I've never messed with the IAT resistor mod.

[1988GTU]

How do you tweak it to run richer?

Adjustable Fuel Pressure Reg.

Will putting a resistor in the IAT circuit retard the ignition timing? I'm guessing around 200 ohms would make it think it was really hot. And the IAT is the little sensor in the air filter housing, isn't it?

I don't know what temps will do what, but that is correct on how to do it.

[theoldshedsquad]

Sweet, thanks for the info. I think the fuel pressure on this engine is around 40 - 45psi, so I'd have to fit a pressure reg to take that down to about 7psi for the fuel solenoid on the nitrous.
Also, can anyone tell me what the little black box on the rear shelf is, or what it does?!

[BMC]

Sweet, pull that engine out, stick it in an MGB and you'll drop a few seconds without even trying. That's what I did! :-)

http://60degreev6.com/forum/garage_vehicle.php?do=view_vehicle&id=11

Seriously though, whatever the end results with your Pontiac, post here. I would love to hear the end results in that car with a 150 wet shot. One of the cars we built here had a 50-75 shot dry. We never did get that thing to the 1/4 mile track but it was always one of the fastest going around corners with the crowd we were around.

-BMC.

[3400-95-Modified]

I ran a 100 wet shot constantly on a 3400 SFI motor, stock build and never had problems with it... Other than the occasional headgasket leaks... I went through 2 sets... but that was in 60k mile time frame. Dynoed 144whp n/a and 206whp with the shot. 168tq n/a and 238tq with it IIRC... Car turned its fastest time of 13.818 with full street trim and stock manifolds full 2 1/2 exhaust.

That motor is now getting all new gaskets and going back in my daily 95 car. I cant stand the gutless 3100 in there.

[theoldshedsquad]

Well, for what it's worth, I put a strobe on it last night. Disconnecting the IAT made no difference to the timing. Bridging the IAT wires with a 200 ohm resistor made no difference to the timing. In fact, nothing made any difference to the timing! I was going to start on the knock sensor, but that is tucked WAY out of the way at the back of the motor, and can only be reached with the car on a ramp or hoist ...

[rsisbetter]

I ran a 100 wet shot constantly on a 3400 SFI motor, stock build and never had problems with it... Other than the occasional headgasket leaks... I went through 2 sets... but that was in 60k mile time frame. Dynoed 144whp n/a and 206whp with the shot. 168tq n/a and 238tq with it IIRC... Car turned its fastest time of 13.818 with full street trim and stock manifolds full 2 1/2 exhaust.

That motor is now getting all new gaskets and going back in my daily 95 car. I cant stand the gutless 3100 in there.

your car put down 144whp, with a 3400? stock? mods?

can one spray 100 without "needing" to retard timing?...

[theoldshedsquad]

Right, having a few problems. I managed to borrow a cheapo SunPro code reader today - the sort that flashes codes up using your "service engine soon" light on the dash. Problem is, I didn't have the book that tells you what the codes are! Can anyone help?
Codes were 1-2 (which I think is the standard first code flashed)
then 1-3
then 2-3
WTF!?

Incidentally, my muffler dropped off last week, so I cut the catalytic convertor out (when you shake it, it makes a noise like there's a golf ball in there ... not cool!) and replaced it with a Cherry Bomb, then a straight pipe in place of the muffler. Sounds good!

[1988GTU]

23 Intake air temp sensor error (low temp indicated)
13 oxygen sensor circuit open

[Superdave]

this is probably very close to the spark advance table you have (this is from a 92 3.1 automatic Cavalier)



85-100 Kpa is where you'll be (that's WOT) VS the RPM.. the SA is pretty conservative there. I'll look deeper into the code to see if there is something you could do to lower the delivered advance.