Quote:
Originally Posted by p4msi1
In my opinion , at 15 degrees your motor is very restricted and not happy producing alot of heat that is unnecessary . Do you have a EGT gage hooked up?
Tiger heads liked 15* on a 200 shot but compression was 12:1 and I was on C16 fuel. Now I am on E85 and 9.6:1 compression and am almost totally in the dark on what this motor will want for timing. The 2 fuels have different characteristics so I figured to start safe. If I had e-heads or iron heads maybe I'd start higher??? Even with 15* on nitrous I still torched the block and pass. side head and lifted ringlands. Strange thing is, I had local nitrous gurus inspect the plugs and they all said the tune was as good as it could be!
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This is my opinion on that. Nitrous is much more violent then adding just pressured air from a turbo.
C16 burns at a different rate then e85.E85 also burns cooler. Change those 3 facts you have a whole new stuation. So maybe it wont be as bad as you think?
Just the fact that you can say bumping the timing only 4 degrees really freed up the motor is telling you that you're heading in the right direction.. Follow the signs . 15 degrees of total timing is very low.. Scary low in my opinion. A 200 shot is more destructive then 15 psi in my opinion. A 200 shot on a bench test sends a manifold flying up off the bench ! lol. Dont mind me im just thinking out loud here !
One real imoprtant thing here is to stay on top of those head bolts. If they losen it will blow the gasket maybe even torch the head. Most guys torque the head once, maybe 1 other time. Thats a big mistake when you have boost involved . I have a probe in every primary tube. So i know what happens lifting on and off the throttle. One lift of the throttle the EGT's will drop 1000-1400 degrees in a millisecond. It use to blow my mind watching it. How many times do we throttle are cars. lol. So imagine the hot and cold effect is having on the aluminum . It starts to anneal it to the point of no good. So now the bolt towers start to sink from the meterial not being capable of handling the clamp load of the fastener , which in turn blows the head gasket or even worse in some cases .
Sorry , Ive just been through it . Only trying to share what i had to learn the hard way ...