Here is the deal.

I've got about 7K on my motor with the turbos. During that time it was making about 600rwhp on a dynojet, but the actuators were not the correct ones.

So I'd get 10psi of boost immediatly then they would creep to 15, what I wanted was an instant 15. I also wanted a boost referenced fuel system, which is how it was supposed to be. So I finally bought some new 9-20psi actuators and had them installed.

I never had any engine related issues. I do smell coolant VERY slightly if I really go out and beat on it. I mean I have to do some 1-2-3 gear pulls 3-4 times in a row. In normal everyday driving, pulling a one or two gears here and there is no odor at all. Complete 1/4 mile run there is no odor also.

I have whatever ARE upgraded headbolt there was 2 years ago, its better than stock but not by alot.

Ed Wright told me I wouldn't have too many problems because the way I described my setup my boost was peaking after torque peak and thats why thought I didn't have gasket problems.

Now I had it retuned. Its making alot more power and alot more torque. These results are hard to compare because they were done on 2 different style dyno's. On ARE's dyno it made 583/585, on a Mustang dyno it made 535/537. The Mustang always gives lower numbers.

Now its ad 574/614(630-640/670-690 Dynojet) and it hits 18psi as soon as you wack it, then the actuator takes control and drops it down to 17psi a quarter second or so later.

Here is my dilema...what do I do and how reliable do you think the bolts/gaskets I have on there are now? I have the newest GM gasket available.

If I wait to blow a gasket then I have to shave the head and I gain compression. If I do it now, what do I put on and how much better will it be.

Think its worth the trouble just to swap the gaskets and bolts?

Chris from Katech told me that they have seen Ls1's lift the head slightly on boosted runs, then re-seal without issue over entire engine duty tests without problems, he thinks this is what might be happening to me. Over 2 years I lost less than a quart of coolant and the car runs at 190 degree's even on the hottest days outside.

I planned on doing the gasket swap myself, so its just time and money for parts, but I'm wondering if I should even do it.

Is there a relation to torque and cylinder pressure, and how much different bolts are rated for, either their peak or sustained pressure holding ability.

Here is the dyno sheet, torque is pretty flat but was suprised to see if really drop off at the end. Before I made 500rwtq pretty quick and it stayed above 500 at redline, now it carries better but dips below 500 at redline.

http://mywebpages.comcast.net/econne...Dyno%20002.jpg

<small>[ July 13, 2002, 04:37 PM: Message edited by: NoOne ]</small>

 

Hi Eric, you haven't said what your compression ratio is. If you have stock c/r then your cylinder pressures will be really high when you produce peak torque but only for an instant. You will have a pressure spike. After that you will have lots of pressure which produces torque even while the piston is travelling down the bore. This is why turbo engines produce so much torque, because there is more fuel and air burning for longer in the engine. If c/r is lowered then peak cylinder pressures can end up being similar to those found on a stock engine which is why people lower c/r. I have found on most engines of my own that stock compression allows some 7-10 psi without a problem as long as it's not held for long. You could use a water injection set up to cool the charge as it will probably be detonation and not cylinder pressure that lifts the heads. I view the gasket as a safety valve of sorts. If this was my car I would either leave it as it is or back off the boost. If I did damage the gaskets I would expect some piston damage as well. If I were lucky enough to just blow the gaskets and warp the heads then I would use a new pair of heads and take steps to lower c/r by enlarging the head chamber volumes or use truck heads. Mike.

 

Mike,

Forgot that <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

8.75:1 compression, forged rods and pistons.

 

Cometic head gaskets are the best so far. 18 psi seems very high....was that on pump gas? 8.75 + 18psi on pump gas should equal a bunch of detonation....I would verify if 18psi is actual....where is the boost tap?....For example the LPE guys with stage 2 346 ci = 670ish Dynojet rwhp at 11-12 psi......

 

Onfire,

It was 17 degree's of timing, same power can be had with less boost and more timing, yes on pump gas no detonation what so ever driving on a 90 degree day.

I talked to them about that this morning. It was a PITA to get to the actuators and turn them down so they wanted to see what they could do at its current setting.

Looks like the heads are coming off anyways so its a moot point.

Same power can be had with ~13 lbs of boost and a more agressive tune which is what will happen when it goes back together again. I'll need a little more boost than the LPE cars simply because I run a lower compression.

The heads will get new valve guides, new valve seals, some new springs and probably freshen the seats up, and of course the new head gaskets.

Whats the best head bolt I can buy right now without studding?

I'm half tempted to pull the motor and have it studded, your that far along why not all the way <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />