625 head studs

Goinbyyabig

Goinbyyabig

Free Thinker, Innovator
Joined
Apr 12, 2009
Messages
185
I don't know if anyone has ever tried it, but I'm thinking about using the 625 head studs without any o-rings. I know I was reading a thread somewhere about this but can't seem to find it again. Truck is an 06 Dodge CR, 90 hp tips, GT3788, 2nd gen ATS 3 piece, Arson stg.2, lift pump, etc. I would like to install a second turbo, wondering about options, opinions. Not so much about cost, I just would rather not hack on my 25k mile motor if I don't need to. Any thoughts?:thankyou2:
 
With that turbo and injector combo, you dont need to go to 625's. The regular ARP's will be plenty.

That might work as a top turbo, Im sure that there will be some more knowledgeable guys chime in about that
 
I agree that it's not needed for my current combo, but with a large primary turbo under my existing, I'll need to upgrade. I'm only running about 45 lbs. of boost now, I'm assuming with twins the boost will end up at 60 lbs. or more. I guess I'm looking for opinions on how far I could push the boost up if I invested in the better studs. I would rather spend the money on better parts than having the head cut for o-rings. My understanding is these studs are much stiffer, not allowing the head and block to seperate, under higher cylinder pressures, causing gasket failure, is my theory correct? I also have no desire to raise boost any higher than needed to keep it cool, so there's no "how high can I get my boost" going on, just hoping to keep it safe and cool, that's all. Thanks for the response, Rob.
 
I personally think that you can be fairly heavily fueled, and run 60 to 70 psi on properly torqued arp2000's. And by properly torqued I mean doing 2 or 3 or more retorques,, makes all the difference in the world
 
First, the 3788 is an excellent top turbo for twins. The perfect mate for it would be the gt4508r. This is basically what I used for my first set of ball bearing twins. You could go to 800hp with that combo and still tow heavy.

Anyway, I did over 700 on that set. I would regularly see 75psi and a few times hit 85psi... although I wouldn't recommend it. But that demonstrates the potential. I run arp 2000's with the stock mls gasket. When the head was pulled last year the gasket showed no signs of distress at all-- never a sign of lifting or anything. That does not mean that the results would be the same for anyone else, I may just be lucky. With my current set of twins I have hit 90psi and hit 80-85 no problem... I am still pushing my luck with the 2000's torqued to 130 and the stock MLS. Although, aside from the new twins, I also have a cam, ported head and slightly less compression too. The old setup was a stock bottom end and cam, no head work.
 
Yes 90 is definately pushing it. Although, with proper retorques,, and I also would go to 135, you should be able to handle 70 all day long
 
I've also got the same question, I just got an SB66 and I kow I'll need studs but looking WAY down the road I'm thinking of running an S4T with it and was thinking it'd just be worth running the 625's. Not to hijack but owuld it be safe to run just the studs and MLS when/if I go to that combo or should I o-ring when I go that far
 
I recently had to make the same decision, and with the advice of someone who has "been there and done that" I chose the 625's.

The $500 difference in price was worth it to me to not have to worry about it, now, or wonder about them even more when I decide to add the second turbo.
ANYTHING worth doing is worth doing ONCE! Well ALMOST anything...I do have two kids!:woohoo:
 
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