[TT_6SPD_95]

I have decided to maybe keep the stock twins on the car for quite a while and just set up the fuel just so I can spray the nitrous. Any fuel system guru's out there that know a lot about setting up fuel systems for nitrous? Thanks, your input is very appreciated.

 

[RacerRT]

Enlarge your injectors, get an air/fuel gauge, and a nitrous gauge, it's always helpful to have a fuel pressure gauge as well.

Depending on the amount of nitrous you are using, you will need to increase your injectors accordingly. Whether you wish to upgrade injectors one-two steps (550-600cc), or just jump to an injector system that you plan on using in the future (720-800cc , etc.), is up to you.

Your stock fuel pump should be plenty of fuel needed for a small shot (50-75 shot) of nitrous, this is where the fuel pressure gauge would come in extremely helpful.

Fuel system is usually one of the first modifications you do to your car, to change things drastically. You may choose to upgrade to a nismo pump, walboro, or a Porsche 996 turbo fuel pump, if you wish, but you will most likely end up doing it in the future, if you plan on changing power that much.

If you do change to a larger fuel pump, larger lines is directed, but with stock fuel pump, you shouldn't have much problem with the lines.

When choosing larger fuel lines, use proper sized lines and T's that will give you full effect of the flow. Too large of fuel line, with a too small of a pump, will overwork the pump and cause you too lose pressure. On the other hand, too small of a fuel line, and too large of a pump, will force pressure, and cause you to run lean. As a set fact, too much pressure, and not enough flow, causes a lean condition; which as you probably also works for air.

If you chose to upgrade you fuel system fully, you should direct yourself to an adjustable fuel pressure regulator, which will help you properly size the pump to fuel lines, by adjusting pressure; The stock fuel pressure regulator is not adjustable.

Please give the community more details on what you were planning, and maybe you can get a more specific answer.
Example;
Boost
Amount of Nitrous
Type of nitrous system (wet/dry, etc.)
And anything else I missed..

 

[TT_6SPD_95]

Well, I have done 486 (corrected) at the wheels so far w/o the use of nitrous so the injectors are ok for that amount of hp.

I am using a wet system on the nitrous so mainly all I need is extra fuel going to the fuel selonoid to flow 50-100 shot of nitrous...thats all I want.

I am not sure if nitrous takes less fuel to make the same amount of hp that making the hp on turbo alone would so I am not all that sure that the stock fuel pump will handle this kind of flow now if I try to spray it.

I did 486 RWHP "off the bottle"

I want to do ~586hp "on the bottle"....need to figure out a good way to get fuel to the wet setup of the nitrous.

 

[Guest]

IM INTERESTED IN THIS ALSO, I TRIED TO SPRAY (50 SHOT) AND THE CAR HESITATED AT BOOST, I DON'T KNOW IF THIS WAS DUE TO PLUG'S OR INSUF. FUEL DELIVERY?

 

[RacerRT]

Well, I have done 486 (corrected) at the wheels so far w/o the use of nitrous so the injectors are ok for that amount of hp.

I am using a wet system on the nitrous so mainly all I need is extra fuel going to the fuel selonoid to flow 50-100 shot of nitrous...thats all I want.

I am not sure if nitrous takes less fuel to make the same amount of hp that making the hp on turbo alone would so I am not all that sure that the stock fuel pump will handle this kind of flow now if I try to spray it.

I did 486 RWHP "off the bottle"

I want to do ~586hp "on the bottle"....need to figure out a good way to get fuel to the wet setup of the nitrous.

Now when you say corrected, you mean that you corrected it from hp to the crank, to hp to the wheels?
If you can only use hp at the crank..
Also, if your making 486 rwhp w/o then your not going to be able to make 586 w/. You are lacking drivetrain loss into your equation.
If you are going to use a 50-100 shot of nitrous, I tend to beleive your are going to be using a ITC, or another unit to adjust your timing correct? Otherwise you will end up blowing your motor.

A 100 shot is a lot of nitrous on a turbocharged system, and you will need a larger fuel pump, and lines, etc.. You should take into account that you will have a very good chance of damaging your engine, by using that much nitrous. Recommended for a stock compression motor is 25-75, Although it is entirely up to you, what you do. I suggest against it.

It takes more fuel to make more power, in general rule, you will need 20% more fuel, to make 10% more power. You did not mention how much pressure you were running from your turbos, but I would guess it would be in the range of 20-22 psi?

For 100 shot of nitrous I would lean towards 720 cc injectors, and a nismo, or porsche fuel pump. You will probably want your pump to run max, at 85-90% efficiency. A single -8 line should be plenty of fuel, and will leave it so you have some upgrade range in the future.

 

[RacerRT]

IM INTERESTED IN THIS ALSO, I TRIED TO SPRAY (50 SHOT) AND THE CAR HESITATED AT BOOST, I DON'T KNOW IF THIS WAS DUE TO PLUG'S OR INSUF. FUEL DELIVERY?

You have iridium spark plugs.
That is your problem, hotter running spark plugs produce blow out when introduced to nitrous oxide, to solve this, swap out those plugs, for a set of copper plugs, and gap them appropriately. If you still receive blowout, gap them down slighter, and try again. You should have just enough fuel with stock fuel pump and upgraded injectors to supply a 50 shot of nitrous.
Spark plug blow out is hesitation, Fuel cut is like being castrated, it will immediately cut out, like someone just gagged your engine if you hit fuel cut.

 

[DaveH]

Ok, since you are using a wet system we can eliminate the fuel injectors from the mix. At 580rwhp you will be exceeding the stock fuel pump capabilities. I would add a second pump and wire it off of a relay. Change your fuel filter (if it hasn't been changed recently) and your fuel line will be fine. Get a FPD Bypass kit with the tee in it to run to your nitrous solenoid and you are set.

A 100hp shot is pretty big for the stock twins, it wouldn't surprise me if they don't last too long.

 

[RacerRT]

Dave, some wet kits come with a small external fuel pump, but from what I have seen, is the systems tend to run lean. Because the injection system does not run enough fuel with the nitrous, and adjustment isn't quite in the range, to get it slightly rich. at 100 shot, I'd opt for the excess fuel... which can always be tuned with his choice of fuel controller.
If he is running the 100 shot for top end, he wants all the fuel he can get, or would you chance that your getting enough fuel with the injector system with the kit?

 

[DaveH]

Yeah, I've seen some kits with add-on pumps, but none of the Supra kits I've seen have them.

Once the fuel pump is taken care of, the wet kit can be jetted as rich as desired without needing to change the fuel injection system. Just put in as large of jet on the fuel side of the fogger as you need. Usually the kits come jetted pretty conservatively (rich).

 

[John H]

Tony, I was going to make a post with some information that was actually true, but Dave beat me to it. In his message (qouted below) he says everything I was going to say - exactly! A 100hp shot might also be too much for the motor itself, but it's been done. The intake manifold on the TT doesn't like the #6 much. Dave's N/A intake should theoretically flow nitrous better (more evenly). Also Dave is a nice guy, so he left out the part about this "RacerRT" guy being a damn idiot with obviously no Supra knowledge. Don't offer advice when you have no clue what you're talking about!

John H

p.s. See both of you at TX2K2!

Ok, since you are using a wet system we can eliminate the fuel injectors from the mix. At 580rwhp you will be exceeding the stock fuel pump capabilities. I would add a second pump and wire it off of a relay. Change your fuel filter (if it hasn't been changed recently) and your fuel line will be fine. Get a FPD Bypass kit with the tee in it to run to your nitrous solenoid and you are set.

A 100hp shot is pretty big for the stock twins, it wouldn't surprise me if they don't last too long.

 

[Guest]

Tony,

off topic, I was wondering what fuel pressure you are running at idle, 0psi, and full boost again....you gave me those #s before but the new server deleted old posts.

thanx!

Jonas

 

[TT_6SPD_95]

Ok, since you are using a wet system we can eliminate the fuel injectors from the mix. At 580rwhp you will be exceeding the stock fuel pump capabilities. I would add a second pump and wire it off of a relay. Change your fuel filter (if it hasn't been changed recently) and your fuel line will be fine. Get a FPD Bypass kit with the tee in it to run to your nitrous solenoid and you are set.

A 100hp shot is pretty big for the stock twins, it wouldn't surprise me if they don't last too long.

What would you wire the relay off of to turn on the pump...boost pressure or maybe fuel pressure? I could run it off of boost pressure but I guess that might be bad if I am not running the nitrous...I guess I could put an override switch for the fuel pump though to make the pump stay off. Thanks for your comments, they are really helpful.

 

[TT_6SPD_95]

Tony,

off topic, I was wondering what fuel pressure you are running at idle, 0psi, and full boost again....you gave me those #s before but the new server deleted old posts.

thanx!

Jonas

At 0psi I run 43lbs of fuel pressure and at full boost (~20psi) it runs 67lbs of fuel pressure. That is a little more than 1lb of fuel pressure for every pound of boost, but that is how it is in my car. This info was attained by replaying back the defi gauges peaks and seeing what exactly the fuel pressure was against the boost pressure.