Injector upgrade?

[viper067]

So if I can ever get my heads out of greg good, I've got some good power upgrades going
GG Heads .... cam ... 1.7 RR ... should have compression around 10:1

I'm currently at 386rwhp

My understanding is that the Gen 1 injectors are good probably up to about 425hp.

So what are the thoughts on an injector upgrade?

 

[plumcrazy]

i cant help but id say to talk to 1TONY1 he is super knowledgeable on all things viper and he has an Injector cleaning service. he would be my first call.

i dont know if the gen2 injectors work for the gen1's but thats what im thinking might work with some wiring changes

 

[plumcrazy]

I gotta bust your chops....

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but then i gotta help ya..

start here: http://forums.viperclub.org/search.php?searchid=1391067
found this one quickly for ya: http://forums.viperclub.org/rt-10-gts-discussions/621909-injectors-1996-rt-10-a.html

and there is a bunch of threads to look thru. looks like an easy swap
but id get a hold of 1TONY1 and he can be found here: http://forums.viperclub.org/members/1tony1.html

 

[KNG SNKE]

Thanks plum for the new bookmark lol

 

[TexasPettey]

Do you have an aftermarket computer to tune? Depending on your total setup a move to Gen2 injectors would help get the A/F right. I added them to my Gen1 setup because it was cheap and easy.

While it's all apart, you may want to consider having the intake ported on the TB side and to match the intake port sizes of the heads.

 

[plumcrazy]

did they bolt right on ? no additional mod to the injectors or harness ?

 

[viper067]

Its my understanding that the Gen 2 injectors are a direct fit replacement for the Gen 1 injectors.

I have actually searched, should just put that yes Plum, I did search in my signature

What I haven't seen is any message that ever talks about a Gen 1 who modded and had a performance impact directly related to not upgrading the injectors. I'm sure that when you go big SC, or TT ... a wholesale fuel system upgrade is a no brainer, but I don't think I'll achieve those numbers

As I said, I'm at 386HP right now, I could see hitting 425HP with the planned mods but don't really forsee hitting 475 .. 100HP gain would be nice

When built, I plan to work with DC Performance on the tune ... don't know of anyone in the SE PA area I would trust tuning a Gen 1

 

[TexasPettey]

The Gen2 injectors bolted right on to the '95 intake and wiring harness with no problem.

I got to 475 RWHP on my Gen1 with the following mods. I would expect that if you are getting the full treatment from Greg and are getting an aggressive CAM, you should be at or above 475 RWHP. I've not dyno'd yet after getting a new CAM and increased compression.

GG Heads (305 CFM intake flow)
Ported intake to match Heads and larger TB
708 CAM
Edelbrock Headers
3" High flow CAT & Muffler
K&N filters & smooth tubes
VEC3

 

[Jack B]

The Gen2 injectors bolted right on to the '95 intake and wiring harness with no problem.

I got to 475 RWHP on my Gen1 with the following mods. I would expect that if you are getting the full treatment from Greg and are getting an aggressive CAM, you should be at or above 475 RWHP. I've not dyno'd yet after getting a new CAM and increased compression.

GG Heads (305 CFM intake flow)
Ported intake to match Heads and larger TB
708 CAM
Edelbrock Headers
3" High flow CAT & Muffler
K&N filters & smooth tubes
VEC3

475 rwhp is at or near the max of Gen 2 injectors. At a true 475 rwhp you will not be able to modify the afr to any great degree, when you try to adjust the injector pulse it is already near wide open so there is little or no change in afr. In short, once you go static (about 85% of injector flow) the ability to modify the afr suffers.

 

[Tagoo]

475 rwhp is at or near the max of Gen 2 injectors.

I've seen people make this claim, but I'm wondering if the hp limitation isn't actually higher for NA cars. I've seen info suggesting superchargers "consume" (parasitic loss) as much as 100 hp to deliver boost. If that's true, it seems there is a bunch more fuel needed to create 500 rwhp in a supercharged car than is need to create the same rwhp on a NA car. Basically the fuel needed to operate the supercharge that you never see at the wheels. Would you agree?

If my reasoning is correct, do you think gen 2 injectors start to go static at 500 hp on a supercharged car or on an NA car? If that spec is for an NA car, does that mean gen 2 injectors go static at 400 hp +/- on supercharged cars?

 

[Jack B]

I've seen people make this claim, but I'm wondering if the hp limitation isn't actually higher for NA cars. I've seen info suggesting superchargers "consume" (parasitic loss) as much as 100 hp to deliver boost. If that's true, it seems there is a bunch more fuel needed to create 500 rwhp in a supercharged car than is need to create the same rwhp on a NA car. Basically the fuel needed to operate the supercharge that you never see at the wheels. Would you agree?

If my reasoning is correct, do you think gen 2 injectors start to go static at 500 hp on a supercharged car or on an NA car? If that spec is for an NA car, does that mean gen 2 injectors go static at 400 hp +/- on supercharged cars?

All I can tell you is that I added mods one at a time, dynoing each one. When I approached 475 hp, my injectors were no longer adjustable. No matter how large I made the pulse width, there was no change in af.

Logic would say that it would be worse with a SC. in that case you have to also overcome the increased manifold pressure.

 

[Toma]

Take your injector size, multiply by ten, then divide by a "guessed" brake specific fuel consumption number...

A fairly good NA street motor can pull .45 , but .5 is safe.

So a 24# injector is good for about 480 to 533 engine hp (520)
a 29# is good for 580 to 645 engine hp. (630)

I have my own method, and I would estimate each injector at 100% duty is good for the number in the brackets. Real power, at the engine.

 

[Jack B]

Take your injector size, multiply by ten, then divide by a "guessed" brake specific fuel consumption number...

A fairly good NA street motor can pull .45 , but .5 is safe.

So a 24# injector is good for about 480 to 533 engine hp (520)
a 29# is good for 580 to 645 engine hp. (630)

I have my own method, and I would estimate each injector at 100% duty is good for the number in the brackets. Real power, at the engine.

Figure 15% losses for rwhp, in my case 475 rwhp would equal 558 engine hp or the point where the injectors were maxed. . Another issue is the fact that an injector is typically considered static at 85% of rating, which basically means you lose adjustability at that percent of max flow. I was trying to maintain 12.5 a/f when they max'ed out.

 

[TexasPettey]

475 rwhp is at or near the max of Gen 2 injectors. At a true 475 rwhp you will not be able to modify the afr to any great degree, when you try to adjust the injector pulse it is already near wide open so there is little or no change in afr. In short, once you go static (about 85% of injector flow) the ability to modify the afr suffers.

If that is the case, how are folks getting the 500 to 600 RWHP Gen2 cars without going to different injectors?

I haven't fully tuned the new setup yet, but when I was tuning with the VEC3 for the prior setup, I was able to add/remove injector pulse and see the impact on the A/F ratio. I can dump my VEC file, but I don't think that I was adding that much pulse above the Gen1 fuel map.

 

[rpm9000]

They may be raising the fuel pressure which in turn will give more fuel flow.

 

[plumcrazy]

when i ran nitrous i put down 577rwhp/856rwtq and it was always rich. never starved for fuel. i guess all cars are different though. i always questioned jack on this one and i dont usually question jack.

i never touched fuel pressure

tons of guys in the 500+ range too.

 

[Toma]

A few ways to skin a cat.

What an injector flows at it's rated pressure is all it flows. No magic will get more out of it.

Many guys eclipse what the injectors is capable of, but this can usually be explained in one of 3 ways.

Again, it's not voodoo, rather physics.

1). Dyno performed on a Dynofairy (Dynojet 248c) in Denver with std correction lol. Or something to that effect... high altitude, "generous" dyno to begin with, then a correction factor for the altitude.

2) Increased fuel pressure (as in a blown application with an FMU, fuel pumps, or a dry nitrous kit)

3) Wet nitrous kit that sprays in nitrous and fuel through the plate/nozzle.


These are the most common ways guys "think" their injectors flow more than they do.

 

[plumcrazy]

ahhhh, i see. i ran a wet nitrous setup, taking fuel form BEFORE the injectors....ok, makes sense for that. but how about NA cars running 550+ rwhp with no fuel system upgrades ?

 

[ViperTony]

but how about NA cars running 550+ rwhp with no fuel system upgrades ?

This is what I don't understand. I'm about to find out soon and I'll post my results here.

 

[viper067]

Very interested to see your results ViperTony as my setup will be pretty close to yours .... I'm expecting you to have more compression though....and of course, you are a Gen 2 vs my Gen 1

I guess we'll be able to face off at NJMP

 

[ViperTony]

Very interested to see your results ViperTony as my setup will be pretty close to yours .... I'm expecting you to have more compression though....and of course, you are a Gen 2 vs my Gen 1

I guess we'll be able to face off at NJMP

Very cool! I'm trying very hard to get my tuning done in 2 weeks so I can do any tweaking I may need before NJMP in June.

 

[Jack B]

If that is the case, how are folks getting the 500 to 600 RWHP Gen2 cars without going to different injectors?

I haven't fully tuned the new setup yet, but when I was tuning with the VEC3 for the prior setup, I was able to add/remove injector pulse and see the impact on the A/F ratio. I can dump my VEC file, but I don't think that I was adding that much pulse above the Gen1 fuel map.

You are not going to get 600 hp on 29lb injectors. I ran nitrous and started out with 150 shot and ended up with a 350 shot. At the 150 shot level I had the stock injectors. and was making about 600 rwhp, but, i was spraying in the throttle bodies, the injectors were out of the equation. BTW, the max hp was about 850 on a 255 fuel pump with a booster. I still run that combo.

 

[Dan Cragin]

We have done numerous Gen 1 cars with heads, cam and exhaust using the Gen 2 injectors. We tune the factory engine controller and have plenty of fuel control at over 520rwhp.

Just my experience, yours may differ.

 

[Jack B]

We have done numerous Gen 1 cars with heads, cam and exhaust using the Gen 2 injectors. We tune the factory engine controller and have plenty of fuel control at over 520rwhp.

Just my experience, yours may differ.

I believe the car ran fine, but, if we design it on paper:

1. BSFC = .5
2. To keep the injector out of the static range it has to be kept at .8 of its capacity - that is standard oem procedure.

At max hp and ideal a/f the injector size = ((BSFC) X hp X 1.25)/10. This should be( (520) X .5 X 1.25)/10 = 32.5 lb injector. At 520 hp that would put the car into the static operation of the injector.

It would be interesting to know if the BSFC is actually less than .5. If it were down to .45, you would pick up 10% of injector capacity. Maybe someone with an NA car and either a Motec or Aem could generate the actual BSFC.

 

[Dan Cragin]

Most injectors are rated at a lower operating pressure than the Viper. At 55psi the Viper G2 injector acts like a bigger injector.

You never want to go too big on injectors, just big enough is best.

 

[Toma]

Most injectors are rated at a lower operating pressure than the Viper. At 55psi the Viper G2 injector acts like a bigger injector.

You never want to go too big on injectors, just big enough is best.

The 29# G2 injector is rated at 4 bar (58psi) if my old memory is serving me correctly.

 

[Toma]

I believe the car ran fine, but, if we design it on paper:

1. BSFC = .5
2. To keep the injector out of the static range it has to be kept at .8 of its capacity - that is standard oem procedure.

At max hp and ideal a/f the injector size = ((BSFC) X hp X 1.25)/10. This should be( (520) X .5 X 1.25)/10 = 32.5 lb injector. At 520 hp that would put the car into the static operation of the injector.

It would be interesting to know if the BSFC is actually less than .5. If it were down to .45, you would pick up 10% of injector capacity. Maybe someone with an NA car and either a Motec or Aem could generate the actual BSFC.

Getting a duty cycle of even a stock computer car is easy.... getting a reliable dyno number... that's the hard part.

 

[FrgMstr]

I can't figure out what is more effin annoying, reposts on previously asked questions, or plum posting that big page of ass-eating pointers about searching. Now that I think about it, it is surely the search trash. Want to talk about reposts? I think that search post is REPOSTED more than anything else. Think about that. That post never changes, but conversations about problems and upgrades certainly do.

 

[ViperTony]

The question I have is that say I was targeting 600rwhp NA using my stock fuel system. Based on what I've read here, I'm not going to get to 600rwhp on 29# injectors. So would I need to change my injectors to ones that are large enough to support my power goal? And if so, which ones?

BTW, I have dyno time schedule on 5/26. I'm going to be logging, among other things, fuel pressure and hopefully injector duty cycle. Can the latter be done through PCMScan? I'd be happy to post as much data as I can to support the discussion here. Consider me a guinea pig.

 

[EllowViper]

Fuel pressure is not a monitored system. So I run an aftermarket fuel pressure gauge on my piller so I can see it all the time. Sending unit is in the old shrader valve location. Hangs out around 52-55 psi...but that assumes a correctly calibrated gauge.