Force Fed FE- How much boost before i look at o ringing?

[sumfoo1]

What head gasket should i use and what boost pressure should i consider 0 ringing the engine?

Right now she's sitting @ 9.7/1 CR with a .030 head gasket on it and a relatively large cam (especially for 9.7/1 cr) (262 intake and exhaust @.050) She's a 500 CID pond side oiler.  With Crower crank and rods both designed for way more power than i'd ever turn it to.  Should i drop her compression down further with a bigger head gasket?  I know if i go too far with HG i'll start running into quench issues.

.050 = 9.17/1
.080 =8.73/1
.100=8.5/1
.120= 8.22/1


The plan is two gt4202 turbos (because no matter what the boost pressure, turbine pressure on the 1.15 a/r turbine should stay roughly equal through out the 6 psi- 25psi band i would consider running them at.

"setting it on kill" would be @ 25 psi and would be on race gas or e-85

to be honest i'll probably never see 25 psi even with the forged-completely machined finish rods and crank so if is should stop at 18 or  20 that's fine too.

Long story short... i know turbos and EFI.... i don't know FE engines very well.  My background is in subarus and mod motors and neither would i consider 25 psi to be o-ring worthy but they also have much larger heads with pent roof designs less likely to have hot spots... 

Any intel would be nice.

Thank you,
-bill

[Faron]

Quench is Not as much an issue with a boosted combo ,that said  I am NOT a fan of O-rings , now that we have MLS gaskets , I would use Cometic , leave the Quench at the Min , as it makes the engine more efficient and less detonation prone , Limit the  Boost ,I realize  spouting numbers online these days seems to be the Norm , I still believe in Time Slips , NOT Dyno or Build sheets as Bragging Right , ( if that's your Bag ) , seen too many KILLER COMBOS on Both Dyno Sheets and Build that performed Poorly , make the combo Work ( Tuning ) IMHO

[sumfoo1]

Sorry not trying to brag if that's how it came off  just trying to give a run down of what we're dealing with and how i'm stumped...  I know when sizing turbos head flows and cams are of the utmost importance i didn't know if that would have an effect on the threshold for lifting the heads as the DCR is actually really low due to cam duration and shorter than ideal for a turbo LSA (which may change too)

Trying to make sure i can use the bottom end i'm running to its fullest without having a  really expensive pile of metal.

I don't like O-rings either but i also don't want to be lifting the heads off the motor.
I guess better to know when the heads lift then not to and keep pushing it.

so... i'll go with MLS gasket truth is...  the car will be street driven from time to time and probably be set at 6psi for the majority of its life.  But it will see some track events from time to time and probably some grudge racing at the local 8th mile.

I agree about the tuning. I plan on watching her every move and listening to every hiccup and ping. That's how i learned EFI i kept getting tunes for my subaru and someone would go to number hungry and leave me with a tune that ate the engine and someone else would stay so far from the edge the big turbo combo made less hp than the stock turbo setup i had with a canned Cobb tune.  So i learned how to tweak and tune until i had a wicked legacy that flat rolled out any day of the week... but i also drove to work with the laptop sitting on the passengers seat every day.  (survived 78k miles before it ate the tranny) 

But truth be told this is my first attempt at a full on build so i'm really nervous trying to do everything right because this galaxie is my baby.

The numbers and names are just to get the most accurate info and to prevent getting flamed by people saying "bet you don't even have the bottom end to hold 25 psi on that engine"  I may not... but dangit i'm trying my best to get it there.

[machoneman]

If you get anywhere near 20 lbs. of boost or even have a bad tune-up (read:detonation) not o-ringing is just plain silly as you will pay for it...big time.....if you lift the gaskets once!

[jayb]

I ran 17 pounds of boost with my supercharged FE, using Cometic MLS gaskets, and never had an issue, even when running very lean on the initial tune-up (15.5:1).  Those gaskets make a big difference.  I have two T-80 turbos for an SOHC project that should go to 30 psi, and I plan to use the same approach.  The only time I've considered O-ringing the block is when I'm running copper head gaskets.

[rockittsled]

I ran 17 pounds of boost with my supercharged FE, using Cometic MLS gaskets, and never had an issue, even when running very lean on the initial tune-up (15.5:1).  Those gaskets make a big difference.  I have two T-80 turbos for an SOHC project that should go to 30 psi, and I plan to use the same approach.  The only time I've considered O-ringing the block is when I'm running copper head gaskets.

And THAT  is the voice of experience 

[cammerfe]

Some years ago when I was messing with first a 2 litre and then the 2300 Ford engines and turbos, I used wire O-rings and copper gaskets. My current turbo project---TT on a four litre 'AJ' Jag engine for ECTA---I've opted for Cometic gaskets. They are quite universally thought to be 'The Cat's PJs'. I'd not go back to O-rings! (I ran as much as 25 pounds of boost using all aftermarket-massaged internals.)

KS

[rockittsled]

what is it about the MLS gaskets that makes it so much better than the conformity of the soft copper to the block and head surfaces and around the O-ring?  I do know that in order to use the MLS gaskets, you have to have a smoother Ra number for the surfaces.  Is that Ra number the entirety of the improvement?

[machoneman]

Viton + stainless spring steel. Cometic's site does a fair job of explaining same and also notes the RA required.

http://www.cometic.com/technical.aspx

Yikes, I seemed to 'see' copper head gaskets (in my previous post reply) when now it's apparent they weren't even mentioned! They do of course require o-ringing.  I've also used the MLS gaskets with good luck but in non-supercharged engines.  Funny too that most nostalgia supercharged nitro runners I'm aware locally can't use MLS gaskets as almost all their stuff already has O-rings! Old habits = die hard! 

[fe66comet]

Yeah I remember that conversation. I think the issue was the pressure would go down not up, pretty shure it did. Bottom end failure, can't recall what though? Think Jay has tried everything but sending an FE to the moon LOL.

[BigNate]

First - daydreaming about a 500" FE at 25 PSI makes me kinda dizzy and I find myself slobbering on the keyboard.  Sounds like a whole lot of fun....

Now - I guess the other end of the question is whether in "ends of the earth" build scenarios the FE engine design (around head bolt configuration) is susceptible to lifting the head. 

I know that "back in the day" in the turbo-mustangs world one of the admitted advantages of the SBC engines relative to the SBF in high boost scenarios was that with the five bolt per cylinder head bolt pattern they were somewhat less susceptible to lifting the head.  I know that upsized head studs made of high zoot metal combined with cometic MLS gaskets did the trick for many folks.   If memory serves World Products also made an aftermarket "Ford Windsor" block with a modified head bolt configuration including "extra" bolts (no clue how you do this and consider the thing a SBF) that had some popularity in the high boost crowd...

So - maybe another way to ask the question is "if we exclude detonation conditions, at what level / under what conditions have we seen FE platform engines lift a head / push a head gasket?" 

Maybe some of the old knowledge can speak to this?

[sumfoo1]

That's one of the things i was thinking too..


They can't be too awful prone to it as some of the original blower fuel cars were FE powered.

I know when one reads things like this they're often hypothetical and to be honest it will probably be longer than expected after seeing what she did N/A on pump gas i'll have plenty to keep my hands full for the time being.  (she hit 700 @ 7200 [evil grin])

But in the long run i subscribe to John Hennessey's Motto
"too much horse power is never enough"

That and it's going to be in a car that i plan on grudge racing with at the local track and if i get an infusion of capital i'd like to go for one of these some day.

[drdano]

Without the infusion of major capital, you can still go LSR racing on the 'cheap'.  Not sure if Texas Mile does it, but World of Speed at Bonneville has both a 130mph and a 150mph amateur classes.  130 class is 1 mile prior to traps, 150 guys get it 'easy' with a 2 mile run-up.   Pending no R-*-I-N this year and cancellation of all land-speed canoeing classes, I'll be doing the 130 class with my wagon.   

[sumfoo1]

it's my understanding that those two classes are limited to the 130/150 speeds respectively right?

I'm hoping when all is said and done i'll exceed those in the 1/4 mile.

[machoneman]

They can't be too awful prone to it as some of the original blower fuel cars were FE powered.

You should be o.k. at that power level but......read what the original "engine master" Ed Pink had to say about all the nitro, supercharged SOHC's his shop built in the day for almost all the top fuel and funny car runners. Catch the part about broken blocks.  This with approx. 1,800-2,000 hp, 90% nitro loads, 40% overdriven 6-71's and a single mag/single fuel pump. Tough but breakable. 

http://www.enginelabs.com/features/interviews/the-old-master-ed-pink-reflects-on-sohc-irl-and-midget-engines/