Look at my combo (inside) and help me pick the right injector size....
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Joined: Nov 2001
Posts: 1,582
From: Louisiana, USA
Re: Look at my combo (inside) and help me pick the right injector size....
Well I agree that using too big injector may not hurt a bunch but I would go with a 30# SVO injector for your setup b/c they are rated at 32# at 40+psi fuel pressure. I don't know how much power my 355 makes but it ran 11.24@120mph with the stock 24# injectors in it at 43psi fuel pressure. I would say it makes at least 400rwhp to run 120mph in a 3,450lb car with 3.42 gears and 26" slicks. I know it's time for some bigger injectors and had a set but never needed them. I will put at least some 30#SVO's with my new heads though b/c I should make 30-40more HP and plan on spraying 225HP n2o. I never hurt the engine but my stock LT1 castings cracked a couple months ago after years of n2o abuse. Goodluck later Clint
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Joined: Jul 2001
Posts: 752
From: Double Oak TX
Re: Look at my combo (inside) and help me pick the right injector size....
Originally Posted by Injuneer
Not sure why you have to make denigrating comments about my attempts to help someone, who provided very little info up front. It was a simple ballpark estimate, based on assumptions of:
-estimated flywheel HP
-estimated BSFC
-a rational goal for DC
-stock fuel pressure
Where possible, I estimated on the side that would prevent him from selecting an injector that was too small. Yes, its questionable as to what the HP is going to be (I "erred" on the high side). Yes, you can do much better than 0.480 BSFC on a good dyno tune (I "erred" on the high side). Yes, you can push past 85% DC, but I personally wouldn't. I'm running 70% DC on a 800HP setup, including a 300-shot of dry nitrous. BSFC is 0.053, injectors are 64# Bosch, running at 58psi. All numbers are based on an engine dyno tune, measuring actual BSFC, and "real world" HP.
Based on the numbers, a 32#/HR makes sense, and there is no real cost savings or "plus" in trying to buy a 30# injector and trying to squeeze by.
You seem to assume I've never seen a dyno..... you are wrong.
Simply checking the "clasic (sic) automotive math" would have told you that would happen.... assuming you know the BSFC. You could have saved a dyno pull.
-estimated flywheel HP
-estimated BSFC
-a rational goal for DC
-stock fuel pressure
Where possible, I estimated on the side that would prevent him from selecting an injector that was too small. Yes, its questionable as to what the HP is going to be (I "erred" on the high side). Yes, you can do much better than 0.480 BSFC on a good dyno tune (I "erred" on the high side). Yes, you can push past 85% DC, but I personally wouldn't. I'm running 70% DC on a 800HP setup, including a 300-shot of dry nitrous. BSFC is 0.053, injectors are 64# Bosch, running at 58psi. All numbers are based on an engine dyno tune, measuring actual BSFC, and "real world" HP.
Based on the numbers, a 32#/HR makes sense, and there is no real cost savings or "plus" in trying to buy a 30# injector and trying to squeeze by.
You seem to assume I've never seen a dyno..... you are wrong.
Simply checking the "clasic (sic) automotive math" would have told you that would happen.... assuming you know the BSFC. You could have saved a dyno pull.
I don't honestly trust the math vs actual dyno results as most people don't have their combo optimised. Seen very few actual dyno pulls where anyone pulled much more than 450 rwhp with LTx technology. Jordon Musser did 471 while I was there and I've done 466 but both of those motors had a lot of bucks in them including aftermarket heads and a lot of time tuning. The vast majority are in the 370-415 range and that includes stroker motors .
We dynoed a 396 that was owned then by John Page whom now owns 21st centurny Modern Muscle Cars (read LPE) here in Dallas that came with a dyno sheet from MTI that said over 460. When it was actually dynoed, it barely made 400 and that was with icing the intake. Even very seasoned people need to dyno to verify performance.
I'd put a car on a dyno in a heartbeat before I changed anything at all to make sure what I changed would help. Again....... most people on this list don't take the time to get what the have working properly before adding more mods. Bigger injectors will not make one tenth of a hp gain unless you’re not getting enough fuel. Why not spend the money on something that worked right now vs something that might work in the future?
If you don't have long tubes and a good exhaust, I'd spend the money on that to get something that will add power NOW and that will also add power later. Same for the TB, unless you need it...... you don't need it.
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