yelo04goat

iTrader: (11)

i was doin some searching about boosted 347s and seen the few guys in the title mention that the were running like 30 lbs of boost or something like that and it was years ago...

how were you guys goin this with out 6 bolt heads ?

i am building a 347 and goin to run a TC76 on it for now i know i am goin to max the TC76 out before i get the car in the 9s so i will be upgrading turbos some time in the future to somethin in the 88mm range and would like to get in on the secrets of high boost on a 4bolt head

MUSTANGBRKR02

iTrader: (91)

There are tons of cars in the 9's with around 9-18lbs of boost. If you have a good combination of engine, turbo, transmission etc etc you don't have to worry about 30lbs of boost.

But o ringing the heads helps and dual o rings also.

Broke EF

We ran 9.878 with 9.8 lbs of boost and a 76mm turbo, 370ci though.

Sean

NufNuffZ28

iTrader: (13)

I'd also like to hear what head gaskets high boost guys are running. My block is not O-ringed... Heads are off(or will be... Wonder if its worth ringing them?(SBC)

Pro Stock John

iTrader: (34)

I ran MLS head gaskets in both boosted setups that I had.

Build #1 was 317 heads, YSi supercharger. Went 9.40@143/5.99/115/1.35 on 18 lbs of boost. KP's setup was kinda of similar (but quicker).

Build #2 had Allpro heads and an 88mm turbo. Unknown boost for my 9.44@144 pass/1.35/325's, but went 10.008@139 on 16 lbs on a 1.5 on pump gas. I sold that turbo kit to a buddy and he went 8.8x with it, LS2 + patriot heads... He was around 22 psi on the best pass.

I'd say boost in the 17-22 range and high 8's not a big deal assuming the tune is there, but low 8's = pushing water for a lot of 4 bolt setups. I have a few friends who went low 8's without pushing water but I can only think of two of them.

hellbents10

iTrader: (10)

The 76 should get you into the 9's unless the car is really heavy. Dave's GTO went 9.91@141 with a 74mm turbo @ 4040lbs race weight.

Phil99vette

iTrader: (11)

Are you going to run high boost/high compression or high boost/low compression? If your not scared to run C16 and get the correct block work to handle double digit compression and 30#+ boost, your going to need a couple things. 1) a good block with the correct fasteners 2) A good quality cylinder head with a very thick deck surface, 3) Double o-ring with copper gasket, its streetable 4) Someone who can tune it.

tim99ws6

iTrader: (31)

Meeehhhh....there's only so much you can do (within reasonable cost) to get a 4bolt to work from what i've read:

1) Thick deck head
2) Excellent surfaces on both block and head
3) MLS gaskets if you don't o-ring..hell, Koehler ran o-ring and MLS still, so who knows, haha.
4) CORRECT torque on the head across the entire head.

Beyond that, it's all in the tune and the gas you're working with.

I'm certainly not "high boost", but with only 7.5lbs, we went 9.8@134 in a 3600lb car. That was on e85 making 640 on a eddy-current dyno.

Phil99vette

iTrader: (11)

mark runs O-rings and copper......

tim99ws6

iTrader: (31)

I was talking more to his old motor. Not the current one. I may be mistaken, and if I am, I apologize. I remember seeing him running a MLS on his "starter" motor though, haha.

yelo04goat

iTrader: (11)

last time i had the car on the scale it was 3720.. i am hoping to keep it as far under 4000 with the turbo..

thanks for all the info guys i dont thing i will be ever seeing over 20lbs on the 347...
would really like to start a 6 bolt motor one day..

cjg454ss

iTrader: (27)

i ran a 91mm to 21psi with mls gaskets and the block oringed. that was with stock casting l92 heads on e85, made 1000hp fairly easy.i always run mls and orings, copper tends to leak ive heard.

adam205348

iTrader: (2)

Which MLS gasket? GM LS9 gasket or cometics or what?

wilson34

iTrader: (7)

copper or stainless oring with the MLS?

lafinrat

iTrader: (1)

It's not just the deck that moves around, it's the whole block. Same with the heads, the entire head flexes and lifts up allowing the gaskets to leak. The iron block will take a lot more than the alum obviously.

Here's what I learned from experience on my 4 bolt iron block/Allpro head combos:

5.3 block bored 3mm, 3.622 crank:
- GMPP MLS gaskets dry, ARP torqued to 75 ft lbs; dyno'd great, 1/8 mile great, first few 1/4 passes at 17-19 psi pushed ~8 ounces of water out each pass
- Cometic gaskets dry, same thing
- Cometic gaskets cut rivets out, Hylomar every layer, 75 ft lbs, a little better maybe 4 oz per pass
- retorque to 90 ft lbs; no more water pushing at ~20 psi running mid 8s at ~165 mph 3300#

6.0 block bored 0.030" filled to 1/4" above lower hole in block with block concrete, same 3.622 crank
- 5 layer GM gaskets, copper sprayed on only the outside, torqued to 90 ft lbs; no water pushing yet at over 20 psi running low 8s at ~172 mph

Gonoma

iTrader: (15)

did you get someone local to oring your block?

Blown06

iTrader: (32)

When you guys talk about o-ringing the block and using mls gaskets are yall cutting receiver grooves in the heads? Seems like the groove would have to be cut deeper into the block if not, or am I missing something? Is there a prefered thickness/material wire to use?

yelo04goat

iTrader: (11)

well the car will be hopefully 3850 or so... i will keep it around that as much as possible....

i would like to see 9s on the 347 ls1 block at 9.3:1 compression at about 18-20 psi... really think i can get 9s and being that porky...on the tc76 anyway

thanks for all the info guys im new too the turbo thing i think its goin to be more fun then i am ready for

cjg454ss

iTrader: (27)

Block is half filled
oring is stainless in the block, the head doesnt have a groove. I ran ls9s the past two times but will try ls3s next. the thin deck will barely get you too 1000rwhp with the stock decks.

1dirtyZ

iTrader: (1)

o ring and MLS here too , been running it for years on my iron block with the oring on the block and no reciver groove on the heads .

and make sure your tune is spot on !