Cracked jugs

[ejbbal21]

Ok I have a 2332 84X94
Turbo preped dual 45 dellorto's.
25psi of boost
Msd 6AL BTM
Devils own water/meth injection
044 high flow 44X37.5 heads
I have cracked 3 jugs now and trying to figure out how to stop it from happening. Currently I have .26" of deck height. All that deck height is the jug. I'm thinking about having some custom copper head gaskets made. To get the combustion out of the jug and into the head/head gasket. Is this a good idea or do you guys have a better one?

[Chip Birks]

what octane fuel are you running? What is timing at full boost? Too much timing for a given octane level will pop cylinders. Might be time to either turn the boost down, lower the timing, or put a little more octane in it.

[Clonebug]

At 25 lbs. boost you should be at less than 20 degrees timing especially at high load mid rpm.
It will depend on your IAT's and other factors of course but cracked jugs means pretty heavy detonation.
You had better check your pistons very carefully too.

[madmike]

I too have a BTM 6al until wheel hop to it out cracked a few cylinders too
now I just lock the dizzy @24* and use a high torque starter Haven't cracked anymore cyl's

[ejbbal21]

I'm running 91/92 pump gas I believe I have the BTM pulling a little under 1* of trimming per pound of boost. So at full boost its its in the teens. I will verify that this week.

[Chip Birks]

I'm running 91/92 pump gas I believe I have the BTM pulling a little under 1* of trimming per pound of boost. So at full boost its its in the teens. I will verify that this week.

You might just be at the limits of the combo you are running unless you are ready to change fuels.

[Clonebug]

It would be interesting to know what your IAT's are when at full boost.
I'm curious how much intake cooling a draw through gives at say 12 lbs. boost.

[Chip Birks]

It would be interesting to know what your IAT's are when at full boost.
I'm curious how much intake cooling a draw through gives at say 12 lbs. boost.

This isnt a draw through setup. Blow through 45 Dels.

[Marc]

Preignition's the real problem, but the 94 cylinders aren't very forgiving (they're only .006" thicker at the head than slip-in 87s, after all). If you want a little insurance, consider dropping down to 2234 using AA thickwall 92s. P/N VW9200T1MS is "B" compression height with the same cylinder O.D.s as 94s...

[Clonebug]

It would be interesting to know what your IAT's are when at full boost.
I'm curious how much intake cooling a draw through gives at say 12 lbs. boost.

This isnt a draw through setup. Blow through 45 Dels.

Duh....

Your IAT's are probably to the moon if you don't have any intake cooling hooked up.
According to the online calculator I use you would have intake temps of 300 degrees or more with ambient inlet temps of 120 degrees at 25 lbs boost.

You need a big intercooler or lots of Water/Alcohol injection to get those temps down.

I dump 3.0 gph into my engine at 22 lbs. boost and have seen IAT's as low as 130 degrees F with ambient inlet temps below 100* F.

[yamaducci]

This is exactly what I have gone though with my 2498 turbo. 30# (by accident during testing) on 92-93 octane, 24* max, no intercooler. Blew a quarter sized hole though the piston with the most amount of balancing holes (not done by me). Second time turned the boost down to somewhere around 22# on a hot day and split the cylinder all the way down. Somewhere around 10-12 #'s is a safer setting unless you are switching to 120 octane. Also you may want to move up to an Autocraft cylinder.

[turboblue]

You could really stand tightening up the deck.
I built a 2276cc engine but wanted to use a set of Super Flow heads that only had 47cc in the chambers.
I had Ross make me a set of pistons with a 22cc dish.
Got my deck tight and enough total cc to get the compression down to 8:1.

[yamaducci]

That is what I did this time around as well. Set it at Zero Deck then dished the Wiseco pistons then added a copper head gasket.

[ejbbal21]

So I had my heads hemi cut and want from 59cc to 68cc. Then I had a friend water jet some custom .130 thick copper head gaskets. I then took 2 out of the three barrel spacers out. So I'm running weisco pistons and after talking to weisco decided not to have them dished. The pistons at TDC have zero deck height. You add the .130 inch head gasket and 68cc heads and I'm now at 7.4-1. As it turns out I didn't have a cracked jug like last time but had a leak between the head and the jug. So i had the heads fly cut ever so slightly and sanded that one jug with wet dry ultra fine sand paper on glass until the carbon deposits were gone. The motor is together now and I just got another set of copper exhaust gaskets. I will be filing down the all 6 flanges on the turbo header tomorrow to make sure they are good and flat. Wish me luck.

[ejbbal21]

I have decent Devils own water meth kit that has the 3.0 nozzle in it. I don't know how I would be able to check my in take air temps. I'm going to competition engineering (a local VW shop) and have them tune it on the chassis dyno just as soon and I get it back together. It's a hell of a motor in a Baja running a fully built 091 and 33X10.5 bfg mud tires in the rear.