Is 10:1 compression to much?

vw_bug_owner · Post by **vw_bug_owner** » Fri Nov 02, 2001 10:45 am

I have a 1.9 I am building up, right now..
I am at the head installation, I just figured out my compression... 10.2:1 my question is will it run street gas?

I have a counterwight crank, engle 110 cam, 94mm pistons, and a new brazillain case. The heads are stock 041's with big valves installed. I don't mind running 91 octane all the time, but I don't think I can afford to put racing gas in it all the time.
Please someone fill me in, thanks.

Searoy · Post by **Searoy** » Fri Nov 02, 2001 12:18 pm

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by vw_bug_owner:
<B>I have a 1.9 I am building up, right now..
I am at the head installation, I just figured out my compression... 10.2:1 my question is will it run street gas?

I have a counterwight crank, engle 110 cam, 94mm pistons, and a new brazillain case. The heads are stock 041's with big valves installed. I don't mind running 91 octane all the time, but I don't think I can afford to put racing gas in it all the time.
Please someone fill me in, thanks.</B><HR></BLOCKQUOTE>

With 10.2:1 compression you could run much more cam, so much so that it might be the cam that kept you off the street, not the compression. A 125 would be more in line with those numbers. If you don't want to crack the case open definately lower compression with shims. Please don't Semi-Hemi it. You're beggin for trouble.

------------------
*** Teach a Man to Fish ***
Searoy

"I tend to lean toward a tighter gap and a
looser skirt....a little slap never hurt." -- Joe of the West

Hot Wheels · Post by **Hot Wheels** » Fri Nov 02, 2001 12:21 pm

I ran 10to one on my 2274 mostly as a drag motor. It would run on 94 octaine with a little retard but it does heat up fast. I ran it at the dunes for an hour or so at a time and it was ok but the life expectancy was short for a street motor. It would not have made a good commuter car engine.

vw_bug_owner · Post by **vw_bug_owner** » Fri Nov 02, 2001 12:49 pm

Will it run on street gas?
Also, what does semi-hemi mean?

vw_bug_owner · Post by **vw_bug_owner** » Fri Nov 02, 2001 12:53 pm

Ok, thank you for your replies.
I want to go as high as I can while still runing pump gas. What about 9.5:1? What size shim would I have to stick in there?
(piston was .001" from cylinder wall on TDC)

Steve Arndt · Post by **Steve Arndt** » Fri Nov 02, 2001 12:55 pm

www.aircooled.net then the "tech section" and try the compression calculator. Put in your bore, stroke, head cc, deck, and calculate compression, or any other single variable.

With the Engle 110 you won't be running cool and long term at 8.5:1. I would not go over 8.5:1.

[This message has been edited by Steve Arndt (edited 11-02-2001).]

James2 · Post by **James2** » Fri Nov 02, 2001 1:34 pm

I don't see how your Ratio could be that high. Stock chamber should be about 50cc or so. Even with .040 deck you wouldn't have 10-1. Sure you figured it right?

vw_bug_owner · Post by **vw_bug_owner** » Fri Nov 02, 2001 1:43 pm

The heads heald 50cc's.
Then, the deck height was one hundred thousandths.
And the bore is 94.
I think I did it right.

James2 · Post by **James2** » Fri Nov 02, 2001 2:43 pm

Ok, your math is right, but your going to have to run more deck. Thats not enough, the piston will hit the head at higher rpms.

The min safe deck is .040, which would yeld 9.4-1. I would go ahead and just bump the deck to .050 to be safe. This would peg you at 9.1-1.

James2 · Post by **James2** » Fri Nov 02, 2001 2:45 pm

With the small cam I would try and get the CR down to below 8-1. IMHO. I would go 7.5-1 to 7.8-1.

2LTERROR · Post by **2LTERROR** » Fri Nov 02, 2001 4:00 pm

I HAVE A 2165CC WITH 10.23:1 COMP. WITH A FK8 CAM AND DRIVE IT EVERYDAY ON 92 PUMP GAS AND MY HEAD ONLY GETS AT THE MOST 425 DEG ITS BEEN ABOUT 6 MONTHS NOW AND NOT A PROB.

vw_bug_owner · Post by **vw_bug_owner** » Fri Nov 02, 2001 4:14 pm

I was wrong, my deck height is :
.107 which throws off my compression again....

vw_bug_owner · Post by **vw_bug_owner** » Fri Nov 02, 2001 4:24 pm

I am bad with the conversions, does anyone know what the new compression is?

1914cc
50cc heads
94mm pistons
deck height of .107"

James2 · Post by **James2** » Fri Nov 02, 2001 4:33 pm

8.0-1

Paul (Der Bahnstormerz) · Fri Nov 02, 2001 4:47 pm

My 1776 w/ 110 cam, 40x35.5 heads happily runs at 9.1:1 cr.