MrLexse

Okay. I've got an S4 engine which is coming apart this week.- PO said it was "weak". It's currently on an engine stand. Prior to installing a S/C (one of Andy's kits has been sitting on the shelf for quite a few months), what modifications make the most sense as far as keeping the engine together under short periods of boost? I'd like to keep the engine investment in the $2500 to $3000. range (parts and/or machine work). Don't include labor to disassemble/assemble/install. Water pump, TB and associated parts have already been purchased.

Shane

What is your horsepower goal?

Jim bailey - 928 International

Depends on what is meant by "weak"?? If the engine had low compression excessive blowby all your budget and more will go toward boring ,cylinder finishing and pistons.

Tony

If you have the motor on the stand. Id pull the heads and toss in a new head gasket or MLS type from Cometic.

Other than that, you may as well do the front and rear seal, oil pan gasket, rod bearings motor mounts...all of which really arent required for a SC application. Just good preventative maintenace for any 928 motor when having that access (motor on a stand)

Get your self a leak down tester and check the motor. granted you cant get it to opertating temps for best results but if somehting is drastically wrong it would probably show up.

For giggles i think a set of headers would be easier to install with the motor out. Set them in and drop the motor down on top of them.


Also...save some of the budget for tires

FlyingDog

What about drilling the crank to prevent oil starvation at high revs?

BC

My opinion? Take it apart, send the block to millenium or US chrome, and have it Nicasiled. Then get custom forged JE pistons and rings for a 4" bore or whatever you want from the plating guys. Maybe 8.5 or so, or a bit higher.

Then turn up that twinscrew to 15psi!

Maybe a deck plate from Ketchmi.

MrLexse

Shane: Working backwards, if you get the widest, stickiest tires available for the car, then at the point where you still can't get the power to the ground, add 50 HP. I want to crank up the boost. I'm curious to see at what the weak points of this engine really are. Its alright if this engine dies, so that others might live.
Jim: I'm going to go over the engine over the next couple of days (comp or leakdown test) and find out what "weak" really means.
Tony: How did the piston mods you were engineering work out? Did you end up with 8.7:1? What boost are you running ?
FlyingDog: How much of an issue is that?
BrendanC: Now we're cookin' ! At what boost do deck plates become required?

BC

Tim Murphy, IIRC, has found some "balooning" of the towers on this block at some higher pressures, but mostly under DETONATION, which we don't want to have. My plan, personally, is to not go past 14psi until I have had my initial fun and have another block ready to go - one with forged pistons, and some sort of deck plate.

Honda guys are doing 30psi on sleeves and deck plates. I think you wouldn't have much traction past 750hp - but thats conjecture.

You said 3k or so - so I was thinking 1000 or 1200 for JE pistons, another 1000 for the deck plate and installation, and then 1200 or so for the honing and nicasiling process. Leave everything else stock.

... Or you could spend 1800 on forged rods from pauter. www.pauter.com I think. They are over by me in SoCal.

Cometic Gasket, and....

Or, if you really want to find limits, invest 3k in a computer you can program for the car, and install that. Turn up the boost, and see what the enginewill take exempting detonation.

GoRideSno

Lex,
I see all good advice above.

There is a guy that owns a shop in Northern CA that has done a deck plate on his own block. He says that he welded it in then machined the block and plate to form a new surface. I can put you in touch with him.

If I were going to to spend $3000 on an engine in order to add more boost I wold do exactly what Brendan has suggested here and add oil squirters too and definately do headers too while the engine is out.

As far as the power goal. In the KenneBell Cobra kit the Autorotor MX compressor you have puts down over 700rwhp and that's from a 4.5l engine.
A wide and tall set of Nitto 555 should put a whole lot of power to the ground.


Andy K

FlyingDog

There are a lot of other people here who could explain the crank mods better than I could.

mspiegle

i think devek sells a drilled crank

GoRideSno

Drilled crank not really an SC related mod ie does nothing to increase power or reliability as specifically related to SCing. Not to say that it doesn't raise reliability in general though.
HTH,
Andy K

FlyingDog

Andy, that's true. I was thinking SC=high performance=high revs. The drilled crank wouldn't directly effect the SC, but would allow better use of the SC by expanding the RPM range. Do any of the SCed cars have drilled cranks?

GoRideSno

Matt,
I don't think any of the cars running my systems have drilled cranks.

Andy K

Lagavulin

The 'high revs' part is not necessarily true, unless you build the engine specifically to do so.

One benefit of a supercharger is that you don't have to run the engine at higher than stock RPMs since the supercharger is forcing more air into the engine in a given amount of time without the need to spin higher RPMs.