OldSmokey

You guys with 600+hp do you all have more than just head studs. I want to eventually be in the mid 600 hp level, but dont really want the cost of fire rings or any real big internal mods. What do you guys think will 12mm studs be enough for the hp level? Thanks Joel

dperf

i think 12mm studs are good for the 650-700 range if boost levels are kept in check(sub 60 psi), egts are managable, drive pressure is good and no drugs.

OldSmokey

I was thinking of maybe throwing in a little water/meth, to help with egts a bit ive read that water does add quite a little cylinder pressure tho. Maybe it will have to be all fuel.

WUnderwood

the boost numbers are the numbers you need to worry about, not so much the HP numbers

OldSmokey

Yah, I just dont know what kind of boost mumbers that 650 hp will make, Ive still got my stock turbo with the oem boost elbow, so my boost doesnt get much above 30 psi now. Im thinking about running something like a HTT SS 64 or 66, with the wastegate somewhere around 45 or 50 psi. Is this a little to low for 650 hp? Then i wanted to use the mater to help keep egt's in check.

morkable

I have been told,, Im not sure of the validity of this, but that the stock headgasket with arps can handle up to 70 75 psi. I know lots of guys running mid 50's with stock everything and no problem,, not me personally. But I am pretty sure that when I go to twins this coming winter that I wont need to upgrade the headgasket

Kevin

wap

IMO if you want 650 get the 66 or bigger. Boost is critical when trying to decide if studs will be enough but there is much more to it than that like timing and cylender pressure.

For intstance (this is hypothetical not concrete numbers) it is possible that 55psi with a K31 would be easier on your head gasket than 45psi with the stock turbo, just because the driver pressures are so much less.

OldSmokey

Yah i understand drive pressure, ive just read that the bigger chargers are not always the best for milage. So i was thinking if i split the difference and went with a 64 that would be ok. Should i just go with a 66 then?

RyeThomas

Dont take this the wrong way, but if you want to push some power mileage should not be a concern. I could have gone with Flux 1's for milage, but I wanted power so I went 3.5's. I still get 13-16mpg, and my truck from day one has never been good on mileage. If you want 600+ its better to go a little big so you dont outgrow your setup. Like me Im pushing my twins to the limit right know, and if I want to go any farther I need to address my air issue. Which basically means start over and pay big bucks for another set of twins, nothing like doing things twice .
But as you can see Im pretty happy with my big old dually getting 13-16 mpg with all Im throwing at it. Good luck.

abc4yew

Mine held fine at 70psi....for alot of time....When I injected water/meth and had the timing up to 28 degrees....at 90psi.....not so long... With a planed head and block deck with the thicker gasket I think it would have held. My stock thin headgasket just bubbled between cylinder 5 and 6....not a major blowout...could have probably driven it by retorquing the studs. Ported and polished the head, decked the block, installed all new valve train, new thick gasket... new injectors, back to 70psi till the end. ks

BothellDiesel

Get the 66! don't worry

cquestad

I ran 55-56 psi daily for 100k or so with a A5k on stock bolts/gasket. I am sure the drive pressure was low....

morkable

I have a little silver 62 that works quite well for me. 55psi, good hp numbers, not bad egts. Great fuel mileage, I have gotten as high as 27mpg (on an imperial gallon) very happy. Now to see where I am at on the track next weekend

Kevin

wap

I agree, most told me to go smaller but now I wish I had gone bigger cause this will not be enough charger for me in the future.

I would think the 6-650 would be pushing it for a 66 also.

swalter3

I would go with the 66. I just got an htb2 64-14 and i know that I am going to out grow it very soon .... SO if you know anyone looking for one, or if someone has a set of used twins for sale SEND THEM MY WAY!!!