100.79 Piston
19.49 Racing Rings
9.48 AW "Window Milling" of the inside of the skirt
15.48 Black Skirt Coat Similar to Hard Anodizing has Teflon Seal for prolonged life and decreased friction

That comes to 145.24.  We could spend more getting it lighter but that may decrease strength.  We could get ceramic coating on the top of the piston for 20 something more, or we could just get the pistons and rings for 120 bucks.

Since bigger is no more expensive I vote for doing 97mm.  I'd like the window milling and coating and around 10-10.5 for compression.  What do you guys think?  Soon as we know what we want, i'll get final figures with shipping from ross and let everyone know!

Hmm also i wonder if bore tech might give us a group rate if several of us wanted the same bore/hone size and carbide coating process....

I'm in, 97mm, 10-10.5 comp. , AW, skirt treatment, and ceramic coating. How are we going to deal with shipping?

justin_o_guy wrote on 12/31/69 at 16:00:04:


Transmission strength is a good point, i'm sure there will be some more wear, but more power almost always costs a little in longevity... definately seems like taller gearing (yeah, chain prolly) is in the future. wonder if there are any 6 speeds that could be forced to work...

Ok guys, just got off the phone with Ross, really helpfull people by the way, and heres the skinny.  Pins, rings, and pistons would be about 550 for 4.  The motorcycle tech said we probably wouldn't notice a difference with skirt milling and there is decreased life with that.  Coatings would raise the price a bit and again weren't recommended, he said he'd be happy to sell it too us, but unless we're pounding them with nitrous not really necessary.  Bore size doesn't change price, they do all have to be the same piston, and if we have 20 or more the price will drop quite a bit.  The compression could maybe get even higher than the 10-10.5 we were talking about, it's dependent on the clearance.  If the 8mm deck height is accurate, we could go quite a bit higher.  Still though, my vote is for 97mm with just over 10:1 compression, the price is roughly 137.50 each, this is supposed to be a high estimate the actuall cost may be lower.

97mm 10:1 or higher compression.
Need at least 2 more people.

I'll bet your right about the valve springs, anyone know if they could be shimmed if someone wanted to go even higher compression? Or do you just hafta get stronger springs?

You mean pinging or pre-detonation?  I think we'll be okay on 92 or 93.  With the stock CDI box, not at all.  look up the "possibel ignition mod" thread, though.

With a 3.7" stroke and 8.5:1 compression this thing is set to run on 85-87 octane.  

I've been thinking about this today for some reason when I saw this thread.  

If you go to 9-9.5:1 you will likely need to run 89-90 octane.  At around 10:1, 92-93 octane would be advisable.  Anything over 10:1 and I wouldn't recommend pump gas anymore.  Keep in mind that cams that stay open during the compression stroke will offset the extra compression and be more conducive to high RPM power output.

This is just some theoretical "back of the napkin" calculations, but actual test data will take the final say.  However, the actual test data may not account for extreme cases.

What compression does Lancer run and what's the particulars on his cam?  Anyone know?  Lancer?

Yes I mean detonation (pre-ignition) or pinging/knocking.  I figured 92 should work but also thought it would be close.  Doesn't head design have some affect on it?  

Also, you say no adjustment with a stock CDI box but why couldn't you slot the plate that holds the ignition pick up sensors?  I wouln'd be against machining a new ignition rotor.  (I will show my ignorance to the savage engine here assuming the ignition was designed the same as all the old GS's and GSX-R's!)

I had been leaning more towards Lancers approach of machining the barrel deck but then you would also have to slot the cam sprocket to re-adjust the cam timing.  This approach would solve that.

As far as the buy I am on the fence.  I am just geting ready to start my project and would like to go high comp but have alot of work ahead of that.  Also, is the piston company working off our numbers for the new piston design or do they have stock factory specs they are working off of.  I just want to make sure if I lay down the cash it will drop in and deliver as thought.

Lastly, can someone explain to me why the valve springs would be in question for a high comp engine?  They are opened positively with the cam and closed by the springs....why would the springs need to be stronger unless you were going to push the rev ceiling up?