Injector sizing dilemma

[Tyler_Baker]

Turbo system to be installed with the injectors:

Ported EVO Manifold

Rebuilt/Ported/Balanced 16G w/ HMI 7CM^2 Housing (34mm)

Fuel Control/Delivery Mods:

Rewired Walbro 255LPH HP Pump

Billet AFPR @ 36 psi

Tuning Mods:

AFC2 w/ GM 3 Bar Map Sensor

Pocketlogger

EPROM ECU (Burned new ROM w/all the goodies)

The Situation:

My buddy owes me, and will let his RC 550's go for $180. My goal is to run 25PSI on 93 pump, and tune on a dyno. I will run 20PSI on the street. My question is will the 550's be sufficient enough to run those pressures safely. What about ease of tuning with bigger injectors? I am getting a good deal on the injectors, so it makes me have second thoughts about going bigger. Anyone input would be appreciated.

 

[herostar]

Your best bet running 25psi would be 660's probably. But $180 for the 550's you could try them out. They should work fine. Just use the 550's and see what happens, if you end up needing bigger ones you can always sell the 550's for 200 bucks.

 

[MNGSX]

Bump that AFPR atleast up to a 2g's base pressure... 43.5 psi....

You will be ok I guess with 550's but if you see good 660's around near the 550 price jump on that instead.

 

[Mike 99GSX]

There's no way you'll run 25 PSI on pump gas with that setup and 550s. You'll have serious timing yank!! Only on race gas. There have been 3 or 4 similar threads about this scenario in the past 2 weeks so : here we go again

 

[Tyler_Baker]

Originally posted by Mike 99GSX
There's no way you'll run 25 PSI on pump gas with that setup and 550s. You'll have serious timing yank!! Only on race gas. There have been 3 or 4 similar threads about this scenario in the past 2 weeks so : here we go again

Hrrm, I tried to search...Got any links? Thanks.

 

[Groomz]

http://www.dsm-performance.com/fuel_injectors.php

This might help.

 

[kpt4321]

You need a better turbo if you want to benefit from running 25 psi on pump gas, the 16g will be better off at 20 psi.

You'll also probably want 660's.

There's no reason to turn up the fuel pressure, if you run injectors that are big enough.

 

[Tyler_Baker]

Originally posted by kpt4321
You need a better turbo if you want to benefit from running 25 psi on pump gas, the 16g will be better off at 20 psi.

You'll also probably want 660's.

There's no reason to turn up the fuel pressure, if you run injectors that are big enough.

The reason I chose the 16G over any other turbo was price and condition. It has 500 miles on it when it was starved for oil. So I bought it for $80 and I rebuilt/balanced it for $100 bucks. Knowing why I chose this turbo, you think it would be in my best interest to get the cheap 550's and tune @ 20psi? I am not trying to spend loads of money on this car, but if getting 660's would help me @ 20psi then I would spring for them. This is a street car, and race gas is out of the question. Thanks in advance.

 

[Mike 99GSX]

Originally posted by Tyler_Baker
The reason I chose the 16G over any other turbo was price and condition. It has 500 miles on it when it was starved for oil. So I bought it for $80 and I rebuilt/balanced it for $100 bucks. Knowing why I chose this turbo, you think it would be in my best interest to get the cheap 550's and tune @ 20psi? I am not trying to spend loads of money on this car, but if getting 660's would help me @ 20psi then I would spring for them. This is a street car, and race gas is out of the question. Thanks in advance.

Just get the 660s since you don't already have 550s. You can get them for less than $40 more than RC550s.

 

[RiceKiller_TSi]

I dont think it would be a reliable setup running 25psi on a 16g on pump. Detonation will be an issue even with bigger injectors if you dont have a FMIC. Without a front mount intercooler you'll be pushing superheated air into your intake that 550's cant quench. Yeah, I do think timing would be pulled from the horrid knock you'd get.

 

[Mike 99GSX]

Originally posted by RiceKiller_TSi
I dont think it would be a reliable setup running 25psi on a 16g on pump. Detonation will be an issue even with bigger injectors if you dont have a FMIC. Without a front mount intercooler you'll be pushing superheated air into your intake that 550's cant quench. Yeah, I do think timing would be pulled from the horrid knock you'd get.

Having a FMIC wouldn't make his injector sizing change. They are 2 independent issues. The ECU will pull timing if the intake temps are too high. It will also pull timing if the injector IPW is too high. True, they are both problems but not directly related to each other.

 

[Tyler_Baker]

Originally posted by RiceKiller_TSi
I dont think it would be a reliable setup running 25psi on a 16g on pump. Detonation will be an issue even with bigger injectors if you dont have a FMIC. Without a front mount intercooler you'll be pushing superheated air into your intake that 550's cant quench. Yeah, I do think timing would be pulled from the horrid knock you'd get.

I probably should have added I will be running a liquid phase change intercooler. Stock Talon IC with 2.5 endtanks, 3 hp AC compressor in the trunk, welding a "AC jacket" around the tube and fins. The tube and fin will be used as the evaporator for the R134A. I'll post some pictures when I am finished with the setup.

 

[slowpokin699]

you need alcohol/water injection then try the 25 psi...

 

[Tyler_Baker]

Originally posted by slowpokin699
you need alcohol/water injection then try the 25 psi...

I have the solenoid and the mister at my house, I am looking around for a smaller pump then 120 GPH pump Northern Tool sold me.

 

[dsmturboawd]

Originally posted by MNGSX
Bump that AFPR atleast up to a 2g's base pressure... 43.5 psi....

You will be ok I guess with 550's but if you see good 660's around near the 550 price jump on that instead.

why the #### would he put it at 43? put it at 37 and leave it. hes not a 2g. hes a 1g.

550's will be more than perfect for a 16g.

 

[RiceKiller_TSi]

Originally posted by Mike 99GSX
Having a FMIC wouldn't make his injector sizing change. They are 2 independent issues. The ECU will pull timing if the intake temps are too high. It will also pull timing if the injector IPW is too high. True, they are both problems but not directly related to each other.

Not enough fuel = running lean.
Running lean = more heat. Heat that is transferred throughout the engine. Causing timing retardation. With a FMIC intake air is cooler lessening the chance of detonation from preignition. Larger injectors with better spray patterns definitely offer "more" intake cooling by spraying more fuel. That same fuel cools the intake making for more power. I think air intake temp and fuel are very related.

 

[RiceKiller_TSi]

Originally posted by dsmturboawd
why the #### would he put it at 43? put it at 37 and leave it. hes not a 2g. hes a 1g.

550's will be more than perfect for a 16g.

Yeah, but he wants to run upwards of 25psi on that 16G on PUMP gas. Thats pushing it. for the turbo AND injectors.

 

[RiceKiller_TSi]

Originally posted by slowpokin699
you need alcohol/water injection then try the 25 psi...

I second this notion. They both cool the intake much like a FMIC. BTW that liquid cooler sounds wicked...pics please.

 

[tsi20gawd]

Tyler what up it's Bryan,
look dude just cause i run 25psi on pump does'nt mean you should try it
I have WAY bigger injectors than you .(those 550's were mine remember)and dont give a sh!t about my booty ass rebuilt motor.
when Matt ran his 25psi/16G 12 sec pass the turbo would not hold that boost very long @ 21/22 Psi your talon will be plenty fast enough but DONT push it on those 550's
If your still hitting knockcounts above 6 Ill make Brett drive me up there and tune your car.
you can raise your base fuel pressure to fight knock, on the FWD I was running 58 psi base pressure.

dude just call me I have no idea why I just typed all this:laugh:

lates.

 

[Tyler_Baker]

Originally posted by tsi20gawd
Tyler what up it's Bryan,
look dude just cause i run 25psi on pump does'nt mean you should try it
I have WAY bigger injectors than you .(those 550's were mine remember)and dont give a sh!t about my booty ass rebuilt motor.
when Matt ran his 25psi/16G 12 sec pass the turbo would not hold that boost very long @ 21/22 Psi your talon will be plenty fast enough but DONT push it on those 550's
If your still hitting knockcounts above 6 Ill make Brett drive me up there and tune your car.
you can raise your base fuel pressure to fight knock, on the FWD I was running 58 psi base pressure.

dude just call me I have no idea why I just typed all this:laugh:

lates.

Haha, I figured 25 PSI was too much, but Brett was saying it was possible. Get your 1000cc injectors! Brett needs your 740's and I need his 550's . I'll come down there for tuning, see if we can't get some dyno time at Fame. Lates

 

[tsi20gawd]

dont worry abt fame we dont need an AWD dyno......
I bought a VCE!!!!
28psi FWD burnouts!!!!
hell yeah!
ill have brett hooked up by the end of the month one way or another.
Ive got tues/weds off and sat/sun off after 6:00
so whenever you want c'mon down
later maing!
Brett's right it is possible......but not for long ive had a 14B hit 30 psi before is self destructed.