whats the most compression allowable for 5psi?
This is a discussion on whats the most compression allowable for 5psi? within the Forced Induction forums, part of the LSx Technical Help Section category; No shit? Do I need to go that big for 5 psi? Also my cam is a 112 lsa, someone ...
10-21-2011, 02:40 PM #21
No shit? Do I need to go that big for 5 psi? Also my cam is a 112 lsa, someone mentioned blowby? What is that and will it hurt the engine or just not make good boost?
10-21-2011, 02:45 PM #22
Here is the formula:
To calculate the injector size for a particular application:
Injector Flow Rate (lb/hr) = (Engine HP x BSFC) / (# of Injectors x Injector duty cycle)
Your injector duty cycle should not exceed 80% or 0.8, so use that in the formula. Obviously your # of injectors is 8. Use an estimated HP for engine HP.
For naturally aspirated engines, estimate BSFC to be 0.4 to 0.5
For nitrous engines, estimate BSFC to be 0.5 to 0.6
For forced induction, estimate BSFC to be 0.6 to 0.7
For rotary engines, estimate BSFC to be 0.6 to 0.7
For engines running methanol, double the appropriate gasoline BSFC (e.g. a forced induction methanol engine has a BSFC between 1.2 and 1.4)
10-21-2011, 02:57 PM #23
Generally speaking, you do not want a cam with high overlap and long duration in a FI set-up.
10-22-2011, 01:24 AM #24
so i would be better to get a smaller cam and go back with the 317 heads to make the most power safely?
10-22-2011, 05:37 AM #25
For your case, it probably does not matter. You are only wanting to run 5psi, which is hardly any boost at all. I've seen people use the LS6 cam with LQ4 motors on FI set-ups and have good results.
I'm running the stock cam in my 02 LS1 and I was making 11psi at WOT still with the pulley size which should have gave me around 8-9psi.
10-22-2011, 05:41 AM #26
cool, man you know your shit thats for sure, i been back and forth on it and i think i went the wrong way for a boosted setup, for the cost of the supercharger and supporting mods i could finish the suspension, get a better flowing intake and tb, bigger injectors, dyno tune and be at the 500 mark, and still have money left over, i have wanted a supercharge car so my next project will be a ss with a procharger when the ws6 is done, but i really appreciate the advice and help.
10-22-2011, 05:44 AM #27
You don't want to know how much $$$ I have into mine. It's VERY expensive to have a fast car that all works together.
10-22-2011, 05:54 AM #28
i can only imagine, i am getting close to 4.5 k in mods and i just got the car in April and it had a few mods on it then.
10-22-2011, 06:02 AM #29
With a FI set-up you're going to want at minimum a boost/vac gauge and an A/F gauge too. Doing things yourself saves $$$. I paid $2500 just for the install and tune on my Procharger build. I didn't have the time to mess with it though and I would have rather had an expert do it for me so if there were any issues it would be resolved quickly and correctly. And, there were issues...minor, but still issues. The supercharger and turbo "kits" are far from being complete kits and "bolt-on". There is fab work that needs to be done with the piping in almost all cases.
10-22-2011, 06:12 AM #30
yea i know, my buddy has a 96 ss he bought a turbo for, i think he paid 2400 for the turbo and then another 2600 to have it installed and fabbed up and a tune, although he blew the head gaskets on it and the rear main a week after he got it done, tried to run 10 psi on a stock LT1, now its getting bored and stroked to a 388 fully forged. i go by his house and do a rolling burnout every now and then just to mess with him, lol. thats what scares me about the forced induction - if its not right or the compression is to high then something is going to break.
10-22-2011, 06:16 AM #31
Tune is everything. I had Steve (Frost on here) tune my car. He flew in and tuned mine as well as maybe 10 others that weekend. My car doesn't skip a beat and runs extremely strong. I also only have 23K miles on mine and have owned it since it was new so I know how it's been maintained.
Only engine work I completed was hardened push rods and new valve springs.
10-22-2011, 06:38 AM #32
sweet, see thats what i'm saying. when i get the next project(98-02 SS) i can do minumal engine work, go full boltons and a S/C set up and have an ungodly fast and strong car that s reliable and streetable if i keep my foot out of it, thinking maybe a reman crate motor set-up, break it open and check torque, do the valve springs and pushrods, button it up and go!!
10-22-2011, 07:16 AM #33
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10-22-2011, 07:47 AM #34
yea thats what i decided, when i get the ss project i will go with a procharger.
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