J Chen

Please accept my sincere apologies
Vogel. Hey, I envy you for your
engineering skills & I applaud you
for making the effort & dedication in
exploring a better solution in increasing
the capacity of the engine.
There are a couple of questions that
lingers in my mind which I hope that
can share your views.
1. By going to such a large piston,
wouldn't it lead to a long flame
front & cause incomplete combustion
leading to detonation ?
2. What about the added side loading of
the piston to the sleeve ? Have you
address this buy moving the gudgeon
pin as close to the piston as possible ?
3. I worry about the intergrity of the block
itself. Will the block be able to handle
the added stress ?
4. What about cooling & lubrication ?
wouldn't this need to be address as
well ?
5. Lastly, will the bottom end be able to
handle the additional pounding ?

Sorry for putting up so many questions.
My mentor once told me this : When you
think that you have created a solution,
you sometimes end up by creating a much
bigger problem.


5.

rage2

Raceware.

vogel

J Chen,

No need for apologies!

1. I don't forsee a problem here. This bore is big by automotive 4 cylinder standards, but normal for single cylinders, twins, and lot's of big displacement automotive and aviation engines, both forced induction and NA.
2. I'm not compeletely clear on this question, but my pins are on center in the bore and raised slightly to account for clearancing.
3. I think the block can handle it. I would not be persuing it if I didn't think the block would hold up.
4. Cooling is a great question! This will be interesting to see what it takes to keep all that steel at temp! As you can see, i've added some water passages at the top for additional flow. In my newest sleeve, i even have cooling fins in the body of the sleeve to add surface area. As for oil, i'm planning on a dry sump for my personal engine.
5. Again, I think the block can handle it. Can the crank take it? It's looks good to me. It's a pretty serious hunk of metal and it's already girdled. Do you know of any 944 crank failures that are soley attributed to crankshaft integrity? If I fail a crank i'll build my own billets, how's that for a solution?!

These are all questions that i began to ask when i first tore a 944 apart. I was impressed by what i saw. The meat of my project is not original. It's a new application for a very established method.

J Chen

Hi Vogel,
Thank you for the reply.
Please keep us inform of your
development. I myself am looking
into increasing the capacity of the
engine. Would'nt it be great if you
can weld the sleeve to the block at
not only the top but the bottom too.
That would sure increase the structural
intergrity of the block. BTW, do you
forsee any secondary harmonics problems
by running such big pistons ?

Thanks again

Pauerman

Vogel,

What will the compression ratio be with your 109mm Arias pistons?

Since you machine the factory clyinders away and don't have to deal with a sleeve expanding within a factory cylinder, does having a wet sleeve allow for piston to cylinder wall clearance similar to stock? I know the material of the piston plays a large role when determining this clearance, but I was wondering if a wet sleeve decreases the typical .005-.007" clearance usually found with forged piston applications.

Vic

vogel

My pistons are only slightly heavier than the stock pistons at the 100mm bore. My Ti rods are much lighter than stock, my wrist pins are heavier. I've lightened my crank and i'll be running a light weight flywheel. It will be balanced in the coming weeks. I don't forsee any problems.

J Chen

I doubt so Pauerman. Bigger
displacement equals more heat.
The question on expansion should
rest more on the type of material
used for making the pistons.

Danno

" Since you machine the factory clyinders away and don't have to deal with a sleeve expanding within a factory cylinder, does having a wet sleeve allow for piston to cylinder wall clearance similar to stock? "

Typically, the steel sleeves would expand less than a surrounding aluminium cylinder...

J Chen

Thanks Vogel