[Injectors]: What size......
Le Mans Master
Joined: Oct 2001
Posts: 5,302
Likes: 2
From: Atlanta GA
Re: [Injectors]: What size...... (scorp508)
injector rating = hp X BSFC (usually .4 or .5)
no. of injectors X .8
500 x .5 = 250
250/(8 X .8) = 39.0625
or 500 x .4 = 200/6.4 = 31.25
anything between 32 - 40 lbs., depending on BSFC... I don't know how to determine exactly what that will be though. :cheers:
no. of injectors X .8
500 x .5 = 250
250/(8 X .8) = 39.0625
or 500 x .4 = 200/6.4 = 31.25
anything between 32 - 40 lbs., depending on BSFC... I don't know how to determine exactly what that will be though. :cheers:
Le Mans Master
Joined: Oct 1999
Posts: 9,713
Likes: 3
From: Sachse Texas
Cruise-In I Veteran
Cruise-In II Veteran
Re: [Injectors]: What size...... (Juliet)
I use 30lb injectors on mine. I am expecting about 550 flywheel NA. They are the SVO of course. They worked fine for me when I had 460 flywheel.
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
Re: [Injectors]: What size...... (scorp508)
Scorp, the table for TPI (BSFC=0.5) is on my site, but only goes up to 30lb injectors. At 50-55psi these support about 410-430hp.
The ratio on pressure is the square root but on injector size is linear, so it looks like maybe 34-36lb injectors would get the job done at 55-50psi respectively. It would be best to size to stay in the 45-50psi range. Much above 50psi you might get injector slow down, or so I've read.
The ratio on pressure is the square root but on injector size is linear, so it looks like maybe 34-36lb injectors would get the job done at 55-50psi respectively. It would be best to size to stay in the 45-50psi range. Much above 50psi you might get injector slow down, or so I've read.
Pro
Joined: Jun 2001
Posts: 697
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From: College Station Tx
Re: [Injectors]: What size...... (JD 90 383)
The problem with the flywheel rating is how many people have actually had their engine put on an engine dyno? Otherwise it's all up the air as far as correction factors, etc.
From personal experience, on a NA engine
24lb/hr are good up to 360-370 rwhp. You can make them work up to 400-420, but that is with increased fuel pressure and running them up to 100% duty cycle, and depends on your BSFC.
Over 370-375 I would go ahead and get the 30lb svo's. The 30lb's should be good up to 440-450 rwhp, after that I would look for more injector. Since they don't make the 36's anymore the next cheap step is the 42 lb/hr lightning injectors.
From personal experience, on a NA engine
24lb/hr are good up to 360-370 rwhp. You can make them work up to 400-420, but that is with increased fuel pressure and running them up to 100% duty cycle, and depends on your BSFC.
Over 370-375 I would go ahead and get the 30lb svo's. The 30lb's should be good up to 440-450 rwhp, after that I would look for more injector. Since they don't make the 36's anymore the next cheap step is the 42 lb/hr lightning injectors.
Melting Slicks
Joined: Apr 2000
Posts: 2,793
Likes: 46
From: Elizabeth City, NC
Re: [Injectors]: What size...... (ChrisB)
I was running the 30# SVO injectors in the 90(360RWHP 411RWTQ) and they were no where near maxxed out. Duty cycle was only 80%. And FP was 50# just for a good spray pattern.
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Team Owner
Joined: Aug 2000
Posts: 40,156
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From: San Pedro CA
Re: [Injectors]: What size...... (dtorc4)
injector rating = hp X BSFC (usually .4 or .5)
no. of injectors X .8
500 x .5 = 250
250/(8 X .8) = 39.0625
or 500 x .4 = 200/6.4 = 31.25
anything between 32 - 40 lbs., depending on BSFC... I don't know how to determine exactly what that will be though. :cheers:
no. of injectors X .8
500 x .5 = 250
250/(8 X .8) = 39.0625
or 500 x .4 = 200/6.4 = 31.25
anything between 32 - 40 lbs., depending on BSFC... I don't know how to determine exactly what that will be though. :cheers:
Safety Car
Joined: Feb 1999
Posts: 4,724
Likes: 16
From: Little Elm TX
Re: [Injectors]: What size...... (ChrisB)
The problem with the flywheel rating is how many people have actually had their engine put on an engine dyno? Otherwise it's all up the air as far as correction factors, etc.
From personal experience, on a NA engine
24lb/hr are good up to 360-370 rwhp. You can make them work up to 400-420, but that is with increased fuel pressure and running them up to 100% duty cycle, and depends on your BSFC.
Over 370-375 I would go ahead and get the 30lb svo's. The 30lb's should be good up to 440-450 rwhp, after that I would look for more injector. Since they don't make the 36's anymore the next cheap step is the 42 lb/hr lightning injectors.
From personal experience, on a NA engine
24lb/hr are good up to 360-370 rwhp. You can make them work up to 400-420, but that is with increased fuel pressure and running them up to 100% duty cycle, and depends on your BSFC.
Over 370-375 I would go ahead and get the 30lb svo's. The 30lb's should be good up to 440-450 rwhp, after that I would look for more injector. Since they don't make the 36's anymore the next cheap step is the 42 lb/hr lightning injectors.
Scorp, what you have planned that will equal 500 hp ??
cheers,
Beach
Thread Starter
Team Owner
Joined: Mar 2000
Posts: 83,381
Likes: 87
From: Boston, MA
Re: [Injectors]: What size...... (Beach Bum)
Scorp, what you have planned that will equal 500 hp ??
Safety Car
Joined: Feb 1999
Posts: 4,724
Likes: 16
From: Little Elm TX
Re: [Injectors]: What size...... (scorp508)
Scorp, what you have planned that will equal 500 hp ??
Nothing really new my friend. Just the previously stated system, and a 100 shot of nitrous for kicks. I figure if I get these things as a pre-action, I won't have to dish out the $$ later when we up the cubes. Might as well get em' now! :)
Nothing really new my friend. Just the previously stated system, and a 100 shot of nitrous for kicks. I figure if I get these things as a pre-action, I won't have to dish out the $$ later when we up the cubes. Might as well get em' now! :)
Beach
Pro
Joined: Jun 2001
Posts: 697
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From: College Station Tx
Re: [Injectors]: What size...... (Beach Bum)
If the 500hp is nitrous augmented then
If it is with a dry system I would go ahead and just go to the next "size up" in injectors just to be safe - it is going to require a little more regardless anyway since your BSFC will go up.
If it's a wet system then it doesn't effect the injectors directly, but you will probably want to augment your fuel system. On a vette especially I would just go ahead and fit an in-tank pickup with an aeromotive inline.
If it is with a dry system I would go ahead and just go to the next "size up" in injectors just to be safe - it is going to require a little more regardless anyway since your BSFC will go up.
If it's a wet system then it doesn't effect the injectors directly, but you will probably want to augment your fuel system. On a vette especially I would just go ahead and fit an in-tank pickup with an aeromotive inline.
Safety Car
Joined: Mar 2000
Posts: 3,620
Likes: 2
From: Hillsboro OR
Re: [Injectors]: What size...... (scorp508)
GM uses 24 lbs for 300 hp LT1. 28 lbs for 350 hp LT4. I have come to the conclusion that they spece'd these way conservative to account for varing fuel pressure, clogging injectors, heat related reduction in flow and longevitiy. I think 36lb on a properly maintained motor should be good for 500 hp and still leave some margin of error.
Pintle style injectors like the FMS and Accel are supposed to be limited to 80% duty cycle to keep them from fluttering and overheating. Some margin of error in injector sizing is a good idea because going lean at WOT can be disasterous.
I had a set of 36# Accel injectors that were POS. Avoid that brand. Forget the stuff you hear about idle problems with large injectors < 50 lbs. Shalin ran 50# units on his 355 SC motor with no idling problems.
[Modified by AquaMetallic94LT1, 11:54 PM 1/10/2002]
Pintle style injectors like the FMS and Accel are supposed to be limited to 80% duty cycle to keep them from fluttering and overheating. Some margin of error in injector sizing is a good idea because going lean at WOT can be disasterous.
I had a set of 36# Accel injectors that were POS. Avoid that brand. Forget the stuff you hear about idle problems with large injectors < 50 lbs. Shalin ran 50# units on his 355 SC motor with no idling problems.
[Modified by AquaMetallic94LT1, 11:54 PM 1/10/2002]
Drifting
Joined: Aug 2000
Posts: 1,614
Likes: 0
From: Colleyville Texas
Re: [Injectors]: What size...... (Beach Bum)
Have seen 396's running 400+RWHP with the stock 24# injectors. My 396 is sitting close to these numbers and is running great on the street with the stock injectors at 50PSI. Do plan to go with the SVO30# injectors with the new less restrictive exhaust though.
