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Message started by Commando_Al on 10/18/05 at 10:40:25

Title: Compression
Post by Commando_Al on 10/18/05 at 10:40:25

In case anyone other than me cares, I called Wiseco today about a piston for my savage engine. I had hoped to get one with a higher compression ratio, but they only have stock. They do carry overbores, though.

They said that they could make a custom piston, but the minimum order would be for 25 pieces.

Title: Re: Compression
Post by Reelthing on 10/18/05 at 20:38:52

If the price and compression wasn't crazy I'd chip in for a couple say 95mm @9.5-9.8:1

Title: Re: Compression
Post by commando Al on 10/20/05 at 08:31:19

I didn't get a price on the 25 pieces, but maybe I should. I have to wonder if higher compression would blow the bottom end to smithereens.

This does have me wondering what else could be pinched from the DR650 for use on the savage.

Title: Re: Compression
Post by lancer on 10/20/05 at 09:43:10

The Savage and DR650 did share pistons in the '95-96 model years. Perhaps the hi-comp pistons from the DR could be used.

Title: Re: Compression
Post by Commando Al on 10/20/05 at 11:07:54

That was what I was looking into. Wiseco doesn't carry anything but standard compression for the DR or LS. Perhaps there are other manufacturers, but I don't know where to look.

When I mentioned other interchangability, I was thinking more of the head. A slim chance, but worth looking into, since the port design on the LS is pretty crappy.

Title: Re: Compression
Post by Commando_Al on 10/20/05 at 11:43:37

Also...

Wiseco's literature sez that the same piston is in LS650's from 86-95 and DR650's from 90-95.

Title: Re: Compression
Post by lancer on 11/08/05 at 19:56:05

Commando_Al wrote:

I would be very interested in going in on a batch of pistons...especially for at least 9.5 to 1, if not 10 to 1 compression ratio. That boost from the stock compression would make a noticeable difference on the Savage.

I think the Savage is overbuilt for the power it puts out, and has plenty of room to grow power-wise.

If we can get 5-10 people together we should be able to handle a 25 piston purchase.

Title: Re: Compression
Post by threezukes on 11/09/05 at 06:40:46

Just wondering, but what other things would have to be changed after putting in a high comp. piston? Timing, carb...? or is that all that has to be done?

Title: Re: Compression
Post by Commando_Al on 11/09/05 at 06:43:34

I'll look into what the actual cost would be. One thing, though, since we'd be replacing the stock part, I think that specifying a 10 thou overbore would be a good idea.

In other news, I'm looking into having long intake tubes made. I'm still researching the actual specs needed, but I think it would be a cool old-school approach to more power.

Title: Re: Compression
Post by lancer on 11/09/05 at 07:32:36

If you are talking about VELOCITY STACKS, they are available already and for not too much $$. The one I have is a 6" stack. I did have to make a small alteration but it only took about 15 minutes to do it. It is attached to the carb with a short piece of rubber tube and clamps.

Title: Re: Compression
Post by Commando_Al on 11/09/05 at 11:31:59

I thought a velocity stack was on the outside of the carburetor. I'm talking about a tube between the carb and the head. On a car they call it a tunnel ram. Is something like that available? Here's what I'm thinking of:

http://nort_comm.tripod.com/art/tube.gif

Got a price from Wiseco. They said the minimum order is 24 (not 25) at 122.00 per. The total is around $3500. The specs I asked for were 9.5 to 1, and a 10 thou overbore. The price includes rings, wrist (gudgeon) pins and circlips. 6-8 week lead time.

Anybody here know how high you can go with compression and still use gas from a gas station?

Title: Re: Compression
Post by lancer on 11/09/05 at 12:31:55

The 93-94 octane gas should be good for up to 11 to 1 compression ratio...and maybe a wee bit more. With a piston in the 9.5/10 to 1 ratio range would not be a problem at all for available fuel.

Title: Re: Compression
Post by Commando_Al on 11/09/05 at 12:58:21

Cool. Did you look at my drawing? Here's another iteration:

http://nort_comm.tripod.com/art/tube2.gif

This one would allow the use of the stock carb attachment.

Title: Re: Compression
Post by lancer on 11/09/05 at 18:21:22

Yes, I did see your designs...very nice. Although I don't know that the extra intake length would gain that much in the performance area. If it was just the carb/filter and the intake manifold then it would help...as would a velocity stack and carb. If there were a velocity stack/carb/& manifold...that might be a little overkill. But the only way to know for sure is to test the whole setup...it might boost power afterall.

Your designs a very clean...excellent job!

Title: Re: Compression
Post by Reelthing on 11/09/05 at 21:41:15

lancer wrote:

The 93-94 octane gas should be good for up to 11 to 1 compression ratio...and maybe a wee bit more. With a piston in the 9.5/10 to 1 ratio range would not be a problem at all for available fuel.

I think staying under 10:1 is real fine - any time I've went over it at least with a cast iron head on 93 pump gas we'd get some detonation now granted aluminum runs cooler but since it's air cooled not water cooled and subject to some oil only cooling at idle in the summer 9.5:1 might be all we could reasonably do and still have it streetable all the time.. mark me down for a pair - by the way wiseco have the combustion chamber specs so we don't need to worry with valve clearence and clay measurements , cutting eye brows and such?

Title: Re: Compression
Post by Commando_Al on 11/10/05 at 06:17:20

Wiseco makes a stock compression piston for the savage, so they must have all of the data they need. The guy on the phone didn't seem terribly concerned about the difficulty of it.