what kr is safe?

**matt89** · 07-20-2007, 08:50 PM

I have an sts kit that I've been running around at 5psi and 0 knock retard, so I decided to turn up the boost alittle and watch what happenes. I turned it up to 6psi and did afew wot passes. In a single gear, there was no knock retard. then I did a 2-3-4 gear pass, and at the end of 4th, there was alittle kr. The intake temps were around 175ish and KR was 1.45 degrees at the most. I let the engine pull timing for 1-2 sec's then got off it. I know knock is the worst thing for an engine, but does 1 to 2 degrees of kr hurt much? I really don't want to buy a new engine. BTW, the boost is back to 5 and the car stilll idles and runs great with no kr.

**mrr23** · 07-21-2007, 10:04 AM

1-2 isn't much. try repeating it again. having lower engine and ambient temps might get rid if it. check for repeatability.

**matt89** · 07-21-2007, 11:06 AM

it's not very consistant. If I only do 1 and 2 gear pulls, the ait's get up there but there is no knock, but when I get into the 3rd gear, then it starts knocking in the higher rpms. I feel like the pistons are paper thin. How much can the pistons take at 180 degrees intake temp?! I hear of people with no2 saying kr of 1-2 degrees is normal, but there engine isn't running as hot as mine with the turbo.

**mrr23** · 07-21-2007, 01:10 PM

in the higher gears, you are putting more load on the engine. do you have a way of editing your tune? hptuners, efilive?? if so, then log it and then remove timing in those cells.

**cailey37** · 07-21-2007, 04:42 PM

I agree that 1 to 2 degrees of timing at that level isn't much........have you thought about running methanol injection???? That would cool your inlet air temps and would take care of the knock.......remember.....the computer is going to pull timing out, which you lose power, to keep it safe.....now if you can stop the knock by dropping the temps you'll make more power.....

**Frost** · 07-21-2007, 05:04 PM

ANY REAL KR ON A BOOSTED ENGINE IS TOO MUCH. ESPECIALLY if it's a stock bottom end, and I am surprised you are being told otherwise here.

You can't just turn it up; you have to work fuel and timing along the way. 175degF is out of hand for IATs, buy an IC and/or methanol. Motors can stand being run too hard under boost for 1 gear at a time, its putting 3-4 gears together (like racing) that will do them in.

**cailey37** · 07-21-2007, 05:57 PM

Originally Posted by Frost

ANY REAL KR ON A BOOSTED ENGINE IS TOO MUCH. ESPECIALLY if it's a stock bottom end, and I am surprised you are being told otherwise here.

You can't just turn it up; you have to work fuel and timing along the way. 175degF is out of hand for IATs, buy an IC and/or methanol. Motors can stand being run too hard under boost for 1 gear at a time, its putting 3-4 gears together (like racing) that will do them in.

I will agree that any knock on a boosted motor is dangerous....but I think what he was asking is 1 to 2 degrees going to take away a lot of power.......at the level he's got it's not going to make him lose too much hp.....that is what I was saying......and I said in my first post what he's experiencing is the inlet air temps too high.....methanol will take care of that.....wouldn't do an air-to-air intercooler because it's just going to get you above ambient temps.....so....if it's 95 degrees out....well...he's still looking at temps of 120ish........I went with methanol and got the temps down to 94 degrees.......

**Frost** · 07-21-2007, 06:23 PM

Originally Posted by cailey37

I will agree that any knock on a boosted motor is dangerous....but I think what he was asking is 1 to 2 degrees going to take away a lot of power.............

Well... that's like teetering on the edge of a cliff and worrying that the rocks you are standing on may hurt your feet.

I like the IC and meth approach; especially with a turbo since unless maxxing it out, there is no loss across the IC (manifold referencing and the gate make up for it). But if I could only choose 1, I would keep the meth for the cooling and the octane value.