Slowhawk,
That was a good one.

 

Welp, another vote for GM gaskets and a stock crank

Car was running 8.20's to 8.50's, mid 160 to 170 MPH. Stock cubes, stock crank, GM gaskets. That was 2 years ago. boost ranged from 26 to 30 psi depending on the mood.

My daily driver truck is a stock crank, stock cubed LS1, GM gasktes. 12 psi, pump fuel, 33K miles and counting.

My new motor for the car ain't cheap, but it's got GM gaskets in it.

Cometics are the same construction as GM MLS gaskets, and OEM's are exceedingly picking about sealing characteristics. I have to ask how I can bolt down a set of heads with GM gaskets in between, not worry about coating them with anything, and not have leaks when I see people fight with cometics and copper gaskets not sealing time after time?

 

I've heard nothing but good about the GM head gaskets I would definetly stick to them. And plenty of people are putting out massive amounts of power on stock cranks too. As far as i'm concerned i'm using both of these on my next motor. So far a proven combo to people pushing them farther than I plan to go.

 

I'm going with GM MLS on my new W2W motor. Should be running by next week.

Rob (Bad30th)

 

I guess I should have also mentioned that I'm running a stock crank at 725 going for 900 with no worries. Also ARP head BOLTS @17psi but I may reconsider that when I go for 21psi. stock heads/stock crank/stock intake/stock TB/stock cam/etc. GM stuff is doing the job for me...

 

Harlan,
As you would be considered the expert without question, I would ask, when spending as much time and effort on a motor, would you not think that a forged crank offers a little more protection on the investment, than risking using a stock crank?

I have used the cometics in the past, and they did not hold. so based on information you posted, I have gone with the GM gaskets. That is not to say the cometics are bad, just following suit. By design, GM certainly did not count on anyone using 20psi with those gaskets or with the crank. I wouldnt be surprised if the GM's and commetics were both made by the same company.

A turbo does not put the same stress on a motor as a supercharger so maybe that is the difference. A turbo has a load constantly on the rods on the intake and exhaust side(Which is good) where as a supercharger only has a load on the intake side(which adds stress to the crank and rods). Maybe thats why the stock crank is surviving.

 

Me:
754rwhp
21 psi
144mph
Stock LS1 crank
GM MLS
No o-rings
A1 head studs

 

The new motor has a steel crank in it now. I pushed it as far as I felt safe doing.

It's a totally different animal now. Crazy light funky counter weight callies crank (stock stroke), GRP aluminum rods, new JE pistons with a proper ring stack this time, LS2 block for a normal bore size. I've got Ti/Inconel valved All Pros on it now, but rethinking those since times have progressed since we did the heads.

The targets for this motor are 9K shiftpoint, and more than likely 35 to 37 psi if my math is close. The turbos I've got on it right now should get me ~1800 flywheel, that target is helping me base my boost estimates.

Should trip 190's on a W tire, not sure what it'll do on a big tire. But I'm setting the chassis up to fit a 1490

 

when will see that beast in action again?

 

If my wheels would show up, I can measure for the rear end housing. 12 weeks and counting

 

LME told me to use the copper with the oring center made into it.

 

GM MLS. Shooting for 850-900rwhp, shortly here. Any guess if the a600 weldon will make it. 83lb inj, HP SD tune.

 

NO! Im a 100% on that.

 

I have run the Cometic with good results, they just feel victim to a bad tune. I am going to try the new FP's (.045 compressed) this time.

 

Thanks everyone for all the input. It sure sounds like there is lot of GM MLS fans out there. I come from the older school of thought where a good gasket and studs did the trick. However I am now dealing with 6 less head bolts and a great deal of boost. I have made a choice and I will let you know how it pans out. Unfortunately I can't dyno the thing because nobody around here has a four wheel dyno. With that said I will be using a dyno everyone can relate to, 1320. Results to follow.

On to a different topic: I am fairly new to actively posting on this site and I certainly don't want to offend anyone, but something doesn’t add up. I have been around the block a time or two and when I read some of the sigs I just scratch my head and think how did they do that? I have heard some of you post boost #'s in the 20+ range. Is this on pump gas? Is this on a street driven car? What's up? I see a lot of low 9 sec and 8 sec times, yet there have only been a few of these I have seen and they were far from street trim. When I went low 9's it took a 2500lbs car with a four link, slicks and 275 of nitrous (pump gas!). Please don't get me wrong, I am not calling anyone out or anything of the kind. I just want to know what you are doing to obtain such times.

Many of you probably don't know me or my car and that's ok. I am just trying to gain some insight into the world of the F-body and the LS comb. As I said before I come from the old school days and would like to update my knowledge base with this fuel injection and turbo stuff.

Mark

 

You just won the luck of the draw and got alot of the OG's weighing in on your thread. Seriously. And I am in NO WAY talking about myself. There is good advice to be taken here.

 

Nobody here has run 8's or low 9's on just 93 pump gas. Basically C16, 110, 104, with or without methanol injection. Remember that a full weight 4th gen with a cage is 3800 with driver, so getting these cars down to 3200 raceweight is a bit of work. I ran 144mph at 3450 raceweight.

 

Now that the head gaskets have been decided, now what about head bolts or studs? When are studs REALLY needed and how much torque are put on them. Also, what about main bolts or studs?

 

As mentioned I am running arp bolts at 17psi and they have been proven to 24psi but I can't remember the source of that but it is a sponsor speed shop. I'm going for 21psi.

 

I should be fine @ 15# then with ARP head bolts and the MLS gasket on a 3.903 bore @ 8.8:1 on pump gas.