F-2 Speedy

iTrader: (6)

it was a big inch small block, the engine picked almost 20hp just adding the stud girdles

MILD THUNDER

iTrader: (3)

468s
b&m 420 blowers
superchillers
twin 850 quick fuels

Mark IV blocks bored .060
4 inch GM forged cranks
Manley H beam rods with ARP2000 bolts
powerbond sfi race balancers
JE blower pistons with upgraded pins
speedpro plasma moly rings
arp main studs
EQ 320 heads with mild porting
arp head studs
mls headgaskets
.135 wall trend pushrods
dart adjustable guide plates
comp ultra XD steel rockers
comp stud girdles
morel lifters
rollmaster timing sets
200 seat ,500 open springs
canton offshore oil pans
-12an oil lines
plate style coolers
daytona ignitions

6500rpm dyno pulls, 6200rpm in boat. Made 820hp in full marine trim with wet exhaust with 8psi boost.

Have not blown it up yet, but I think im pushing the envelope on the stock block and crankshaft. I dont think I would want to try much more rpm/boost than Im currently at.

Mohavvalley

I think I'm going to eventually end up just about where your at MT so that's good to know.

How many hours so far?

Thanks

Griff

The engine you are building now and the engine you say you want in the future are not remotely in the same category.

If you want something for 800-900hp, you might as well get rid of everything you have now and start over.

Young Performance

Agree 100%.
I can tell you that I would not build that for a customer. However, being a marine engine builder in a small community, I have to stand behind everything that I build. Every engine leaves my shop with a warranty so I have to be completely confident that it will stay together. I wouldn't be in business for long is I built hand grenades. I have to know for sure that it won't have a failure that I could have prevented.

The biggest issue you will have is fretting of the main cap. Those caps don't have any dowel pins to locate them and the bolts don't have the clamping load that studs do. They only locate on the outer register, which doesn't stop the caps from walking front to back, only side to side. A set of ARP main studs will certainly help.

With all of this being said, I have made north of 1000 hp with a Gen VI block. I've done them over 1100 hp, all in marine apps. I've also been back in them after a few hundred hours and wasn't crazy about what I saw. The main bearings had some odd scuffing on them which indicated the caps were moving. It wasn't terrible and probably wouldn't have failed any time soon, but I didn't like it. They were scuffing right at the parting line of the bearing. In all cases, we ended up going to an aftermarket block with billet splayed main caps that were dowel pinned in place. They will not move....period.

If you are building the engines now, definitely put main studs in it. Don't forget that you will need to align hone the mains as the housing bores will change due to the increased clamping load.
Eddie

articfriends

iTrader: (1)

Eddie, at what boost/hp do feel the extra cyl head bolt bosses in valley are needed? I never had any of my blocks o-ringed, i was running felpros permatorques on my 540 at 950 hp/ merlin 2 block, 12 psi boost, back then mls head gaskets werent really anything i had heard of. Tore motor down to freshen and found fire ring pushed almost to water passage. Switched to dart big m w extra bosses, they couldnt be added to that particular block as there wasnt enough metal in valley area. Also switched to mls, never had another problem even at 1100 hp and 14 psi boost, thanks, Smitty

MILD THUNDER

iTrader: (3)

Posted this in another thread Smitty, but think its pertainant to what you have/asking. They talk about how the cylinder head wants to lift , and how a composition gasket cannot recover like an MLS gasket does. The MLS acts like a spring.

Pros & Cons of MLS and Copper Gaskets

Mohavvalley

Thanks Eddie, always great information with facts/data to back it up, not just opinions with no information.

As always it's a fine balance between building for now and "might as well" for the future and having more data helps make those decisions be educated ones.

if I ARP stud the caps with the GM forged crank what kind of HP will it hold up to for extended runs (10 min plus) around 5,600-5,800 RPM?

Thanks

articfriends

iTrader: (1)

Oh i agree mild thunder, i run mls in all my higher power stuff now, was a real new thing that hardly was heard of 15 years ago or whatever it was. I believe the extra head bosses are a help too. I still havent oringed a block, mark rinda does on just about everything he builds.

Young Performance

The only blocks we've o-ringed was some blown alcohol stuff for racing. But, these were 8000+ rpm with 25+ psi boost and this was WAY before MLS gaskets.

I use the 2 extra bolts once I break 1100 hp or so, which generally equates to about 10 psi of boost.
Eddie