Does anybody have any experience or advice on how much boost I can run with a completely built block, safc2, sfmu,and 660cc injectors? I don't want to through this in and boost over what is safe. I've heard 20 psi is the max, is there anyone who can help me?
#95397, "RE: Safe amount to boost?" In response to Reply # 0 May-30-06 05:59 PM by baxsom
Those injectors with a SAFC is not a good idea. With those size injectors and such an outdated engine management system (you know you also need a SFMU right) your base fuel pressure is going to be so low that the car will not idle correctly. I remember reading that the safc will not even control that large of an injector. Then at that high of a boost some type of ignition amplifier is a good idea so the spark doesnt get blown out.
Finally the fuel system only plays a part in how much boost the engine can handle. You will also need a wideband and its a good idea to use an egt gauge as well to make sure that there is enough fuel. There is also the headgasket, exhaust, valves, pistons, etc.
Then there is turbo size. 20 psi on a 16g is different than 20psi on a 20g. Its like a scuba tank. They are all inflated to 3000psi but have different amounts of air they can hold.
There is just simply no way of telling how much boost a particular engine can handle. Like the commercial says. Just do it.
To give you a starting point and hopefully avoid further benchracing type questions built engine with 8.8:1 pistons, 710 total ccs of fuel via portfueler msd dis2 water injection 3"exhaust
I have been pushing 18 psi for about a month now and the only thing that has given is my turbo seals. The engine is fine.
ps, this post of yours is very close to the last post about engine limits you did. One more benchracing questions and you have yourself a hat trick.
#95408, "RE: Safe amount to boost?" In response to Reply # 1
Originally posted by baxsom your base fuel pressure is going to be so low that the car will not idle correctly
A few years ago I had 415 cc/min injectors with a SFMU/AFC and my idle pressure was around 17-20 PSI. It idled fine, nice and smooth, but at pressures as low as that the spray pattern and atomization sucks so that's why I wasn't able to pass emissions.
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