86 951 Driver

How will you do a closed deck? Will you make a deck plate?

blown 944

Maybe use an MLS to see what's happening.

However, since you do have mids I'd go with the o-ringed block and receiver grooves and a copper gasket.

What studs are you using?

dnovak

Deck plate, no. Block girdle yes. pictures are coming and I think the prices will be the best out there.

I have one going through machine now,,, I know this has been done before and we are not the first but I think the price will be right and with the right fire ring design blown head gaskets will be a thing of the past.

Watch for a wild 16V / 8V option to come as soon as I get the block shipped from Lart,,, he has been busy!

dnovak

I guess it can be called a deck plate as well, it all depends on your definition of each.... no matter how you slice it it closed the deck and holds everything in place real real nice

eman930

Dont they use deck plates?

Wormhole

Rim328, what kind if ignition timing are you running with that Motec?

michaelmount123

This is sound advice! Your head gasket (failure) is a result and not a cause. You likely have a tuning issue.

rlm328

Engine was re-built using Raceware hardware

Timing is variable dependent upon where you are on the ignition map. Engine was tuned on a dynojet over a 4 day period to help eliminate variables

I may have a tuning issue, the pyrometers at the exhaust header inlet all read evenly throughout the power band during tuning so I don't know what it would be. The data download from the Motec at the end of the run that blew the head gasket did not throw any errors and a review of the data did not indicate anything obviously out of sorts. The down load from the data logger also did not indicate anything abnormal.


One of the issues we noted during tuning was a harmonics issue between manifold pressure and fuel pressure at the upper end of the power range. We think that this may have been caused by a waste gate (presently a Tial F46) that is either too small or has a bad spring. I am leaning toward a bad spring.

I am running about 200 kpa to 215 kpa (AiM dash doesn't have PSI) manifold pressure, so boost is not excessive in my opinion (1 bar or 14.5 psi).

rlm328

Heads and block were machined during the re-build so all surfaces are true.

fortysixandtwo

For those that do not want to convert:
200 kpa to 215 kpa ≈ 29psi to 31psi

Edit: kPa values given are in aboslute, so, yeah, 14ish psig of boost.

Rogue_Ant

Kpa is an absolute value (kilopascal absolute).
So to get positive pressure you need to account for atmosphere.
So ~30 - 14.7 = 15.3psi

dnovak

fortysixandtwo

Meh, no ref to "a" or "g". I've seen kPa listed both with a trailing "a" or "g". Most systems read gauge pressure, and the previous comment about high boost being a possible cause of gasket failure, I figured the "g" was left off.

rlm328

The Motec reads/operates off of manifold pressure. The manifold pressure will be atmospheric + whatever boost is being generated at the time. I am set for 200 kpa, but I will see spikes to 215 kpa. When not under boost the manifold pressure is in the 100 to 110 kpa range. Which is as Rogue Ant described it and as alluded to when i mentioned the boost was not excessive being in the 100 kpa / 1 atm / 14.5 psi range.

Now back to copper head gaskets. I have ordered one, so what is the best way to seal it against water leaks?

m42racer

I have several fully Closed Deck blocks available if anyone is interested. These were spares. 2.5L and 3.0L. blocks. Never needed them and they have been sitting in storage too long.