I did a v6 to v8 swap last summer.
Ran strong na, 390rwhp at TEA's dyno when they were still down here.
12.1 at 113 mph in the 1/4. Drove it on the street, no problem. 2500 miles on it.

Put an STS turbo on it. Finished the install last weekend.

Drove it around the subdivision yesterday morning to warm it up, make sure nothing was loose, rubbing, etc.

After work yesterday, took it out on the highway for it's maiden voyage. Warmed it up in the driveway first. After 1/2 mile of driving, I went about half throttle for a moment, and saw 2 psi briefly. So far so good.

After one mile of driving, I nailed it in 3rd gear (auto). 5 psi for about 2-3 seconds, then POOF and big cloud of white smoke. Missing, power was down. Nursed it back home, white smoke every time I was on the gas. After I let it cool, check the vital signs. A little water in the oil. Can't see the water in the radiator. Sounds like head gasket to me. Haven't pulled the plugs yet.

I used ARP head studs, and had the heads o-ringed. Went through 3 stud stretch cycles, then a final torque, in GM sequence each time. Stock pistons. 5.7 heads (TEA - slightly milled, but opened a little too, so net effect on compression should be zero). Stock graphite gasket. 224/228 .581/.588 115 cam. 11:1 a/f according to the LM1. 15 degrees timing. New TR6 plugs at .035.

Why did it let go on the first wot pass, and at only 5 psi?

If I don't find any damage other than the gasket, other than replace the gasket, what else can I do to prevent it from happening again?
I thought studs and o-rings were overkill already.
Different gasket material maybe?

 

Def a blown gasket. What kind of metal ring did you use?

 

were you datalogging during the run?

you sure it was only 15 degrees timing?

I was going to say tuning right off the bat, but 11:1 and 15 degrees should be more than safe.

Sounds like you did everything right to me. Hopefully it's not something like your heads are not perfectly straight or something like that.

 

Were both the deck and heads checked for flatness before assembly? We there any problems before the installation of the turbo? Does STS recommend MLS gaskets?

David

 

I don't know how the stock LS1 graphite gasket is, but I've had some head gaskets that have trouble with O-ringing (namely ones with a "Fire ring") of the block. If you don't see any signs of leaking, maybe try a different brand of gasket. I've found copper gaskets work well with an O-ringed block.

 

According to my TEA invoice it's .041 stainless.

 

No, I wasn't logging it this time around, I wanted to hit it one time with just the LM-1 and make sure the a/f was in the ball park first. Plus I still need to put the passenger seat back in it, so I didn't have a good place to set the laptop.

I set the bottom 2 rows of my timing table to be 15 degrees, from about 2800 rpms and up. Those are either 95 or 96 kpa, and 100 kpa.

 

The heads were Stage 1.5's from TEA, and I had 2500 miles on them.

The deck was not checked though...

No problems before the turbo. (other than traction.)

I haven't heard any recommendation on gaskets from STS. Since it's designed to be a bolt-on for a stock engine, it should be good with the stock gaskets too.

But I'm wondering if o-rings and graphite are a good mix.

 

I've heard of the fire ring problem.

I may give copper or mls a try, on this next go-around.

 

This is going to get me worrying now. I too have TEA o-ringed heads using a fel-pro 9199pt graphite gasket. Brian assured me they have used this combination before without issue just as long as new head dowels are used and the o-ring is checked against the fire ring before final torque. Brian suggested installing the head and tightening the studs enough to cause the o-ring to indent the fire-ring, then removing them to check for centering in the fire-ring.


Did you do this when installing yours?

 

uhh, what controller are you using. V6 to V8 swap....

Spark table isn't a MAP reference, you sure you really had 15 degrees?

 

Mine are GM graphites. No fire ring. (as far as I remember anyway)
I didn't have the heads off after I started the ARP stud break-in procedure.

 

I put a V8 pcm and harness in it too.
Hptuners for tuning.

There is a base table, and there is a MAP vs. RPM table. I did the MAP vs. RPM table. This is the one that occurs as both a high octane and a low octane table. I made sure I updated both with the same values (meaning I didn't forget and leave higher values in the low octane table).

But I didn't touch the base table - didn't even think about it. (but I've never had to touch it for any of my other tuning - although I was always adding timing above stock, before the turbo install, so maybe that makes a difference.)

 

What year PCM?

The spark table is air based not MAP. If you were getting 15° at 11:1 on 5 PSI your headgaskets would still be ok. You're probably not getting the spark you think you are.

 

'98.

Yep, you're right about air based vs. map.

The "base" table and how it factors in, is bugging me now...
Big hole, if I missed that, and if it counts.

 

Sounds like you edited the wrong table. Spark is definately based off the maf unless you have converted to 2/3 bar speed density.

Sorry to hear about problem, gaskets went from detonation. I can send you my timing table from when my car was on 6psi with a 67 unintercooled if you want. It was tuned in las vegas so it's definately conservative if your in a cooler lower altitude area. I've tuned several turbo and supercharged ls1's. You have to avoid detonation no matter what.

If you haven't changed your max retard vs rpm power enrich table from the stock 4 degrees to 10 degrees yet do it. Stock the pcm only allows about 4 degrees to get pulled to try and stop knocking. By allowing it up to 10 you stand a much higher chance of stopping any knock. On a good tune you should never see knock.

For what it's worth I've been able to push 10.5 psi (intercooled) on 91 octane stock motor and The most knock retard it ever sees is 1 to 2 degrees once in a great while, like 1 out of every 10 pulls. Now I have alky so it's a non issue, at least until summer comes.

 

ouch, yah you gotta log every time out until your positive your tune is spot on.

sounds like you didn't tune quite right.

luckily it's only a gasket.

if you want since your using a 98 pcm like me you can send me your tune next time and I will sanity check it for you.

I am not a "pro" tuner, but have kept my car together after 2 different blower combinations and now the STS. Car has been FI for over 40,000 miles (80,000 total) and still going strong, so I must be ok at tuning

 

Zombie, what kind of numbers are you throwing down these days on 10psi?

Mine so far on 5.5 are in the sig. Still have more tuning to go, then I will install the boost controller and go from there.

 

I was referring to the table the wrong way in the earlier post... But I was using the correct table.

In hptuners it's called "Main Spark vs. Airflow vs. RPM, Open Throttle/Moving, High Octane". The y-axis is g/cyl and the bottom 2 rows are .96 and 1.00. The x-axis is RPM in 200 rpm increments. I did the low octane table too.

The table I was recently worried about (while I was at work and going at all this by memory only), is called "Base Spark vs. Airflow vs. RPM, Closed Throttle, In Drive" and there is also one for "In Park". But now that I have read up on it again, I think this table should not be a factor for me. As long as my TPS reading is more than 1.2%, the pcm is supposed to use the Main Spark tables, not this Base Spark table.

I would definitely like to see your timing table.

I did increase the amount of kr that is available.

 

I'll send you my current tune, and you can sanity check it for me, before I make any other changes to it...