TonyG

The question is.... on a race car or a street car? There's a huge difference between sustained loads and momemtary/short burst loads.

350RWHP on a street car can last a long time on the aluminum bores.

TonyG

Fluidplay

True...completely agree Tony.
In my case the car is primarily a street car. I participate in 2 maybe 3 track days a year and a half dozen Ax's. The hp goal when all is said and done is 325rwhp.

TonyG

opps... double post


TonyG

TonyG

Got it.

The issue is the sustained load on the track days.

At 325RWHP, it should be OK if you have it tuned properly with decent fuel.

But.... if you're going to the expense of building an engine.... a sleeved engine will be far more durable and far easier to rebuild than one with aluminum bores.

You can pay now... or you can pay later....

TonyG

gpr8er

Last time I dynoed my 3.0 it made 368/375. It had a miss at about 6k, since then I added an MSD 6A (thanks Tom) It's a street car with a few track days a year. At the time of the build I decided, since supposedly it was the last set of Andial turbo pistons they had on the shelf to go that route. Originally I thought I could get the whole project done for less that 6k. lol....
I had the turbo and pretty much everything else already. I used a 2.7 block and head, S2 crank (knifed), Pauter rods. The machine work was relatively cheap. Probably $1500~ including all the crank work and balancing everything. Never really added up all the receipts but I'm sure it's well over 10k.

Anyway back to the point of the thread, Mike @ Engine Supply knows what he's doing. Since he's in Santa Ana/Newport Beach area there's a lot of exotic stuff that goes through his shop.

Fluidplay

gpr8er, thanks. Santa Ana is much closer to me, I will give Mike a call tomorrow.

Is your blocked sleeved?

gpr8er

nope, straight Alusil.
Tony makes a good point about sleeves though. Put it this way the Mahle piston set from Andial was $1800. If this motor goes south...
I have about 3k miles on it now and a couple of pretty good Willow track beat days on it.
BTW I know Mike did a wet sleeve 951 motor last year

and another BTW..
Castillos Crankshaft Specialist
(714) 523-0321
14654 1/2 Firestone Blvd
La Mirada, CA 90638
did the crank work

The Balance Shop in Santa Ana did what they do.

LUCKY DAVE

I have had unsatisfactory experience with coated aluminum bores, but admittedly this was in a supercharged nitrous land speed engine (Aprilia v-twin).
The aluminum bores aren't strong enough for big horsepower, they go "barrel shaped" to the tune of .004" mid stroke.
The solution was steel liners from LA sleeve, and CP pistons with liner-compatible ring material. We have had no problems at 400hp/liter.

blade7

I dont see the connection ?.

kev951

I have built many engines and have had no problems with motorworks in Sd. I've built multiple 2.5 turbo engines with vitesse software being big tracked and autocrossed frequently. Usually 2.5 alusil with wossner pistons

LUCKY DAVE

It's this.
If you want to make BIG horsepower, aluminum bores (coated with whatever you like) don't work. It's not a question of coating hardness or durability, the aluminum isn't strong enough to maintain shape.
A few on this board are flirting with specific outputs high enough for this to matter.

TonyG

Racing is racing. Everything else isn't racing.

The aluminum bores won't stand up to racing on an engine that's making big power. This is well documented by pretty much everyone from people like me to big name shops that build $75k 951 engines for people that threw a LOT of money at racing 944s for the last 25 years.

Yes they will last for a while... but not long. They always get scorred (or crack). It's just a matter of how long. The aluminum bores are simply put... just too soft.

And it's not the pistons that are the problem. It's the cylinders. The factory pistons, while heavy, are excellent pistons and pose no problems in terms of reliability. If I were going to use a factory bore.... I would only use a factory piston. There's no reason to use anything else on a factory bore.


TonyG

TonyG

People try to alternative solutions to sleeves. They apply hard coatings to the aluminum bores in an effort to get the piston to ride and wear against the hard coating rather than the aluminum bore.

This method is used in an attempt to utilize a standard forged piston on an aluminum bore.

That's what he's referring to.

And that doesn't work either.

TonyG

TonyG

kev951

Who's car is that in your avatar? (if it's yours, where did you get it?)

The color is not typical and looks familiar. That' why I ask.

TonyG

blade7

I see, thought he was suggesting Alusil is a coating. I read somewhere that Nikasil coating or variations of it dont adhere well to Alusil cylinders though they do work well with iron cylinders.