VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 4-cyl high-compression pistons

I was told they exist. Anybody heard of them or used them?

[ December 15, 2001: Message edited by: RustyFender ]

Egge in California does make these pistons (approx. $325/set). I was also told that a different company has made tham, but am unable to remember their name. I thick the "high" compression calculates out to 6.8:1. Chevrolet did list a high compression piston in their 1939 and 1940 4-cylinder parts book.

Hi cufrcp, maybe I should call up Egge and see what they have. I thought they only carried the stock pistons. thanks.

[ December 17, 2001: Message edited by: RustyFender ]

Hi all,
Well I called up Egge for fun and got to chatting with one of their guys and he told me Egge doesn't make a "high-compression" piston for the 28 Chevy with a stock head. He said they have custom made them in the past for somebody using a different cylinder head. They have a limited set of molds they use. However, he did say the pistons they do sell as stock for this engine are about 1/8" taller than the original pistons. I'll let you know if I find anything. Thanks!

-Rusty

Hi.. I got a set of High compression pistons from
Gary Wallace, St Louis that came from Egge.. I put them in my 1925 speedster and used a 28 head,
it now has a 110 compression ratio and runs great..
roy

Hi oldchevman,
I assume you mean 110 PSI compression? That's fantastic. Last time I checked my stock engine, it had about 60-65 PSI at each cylinder. I should have my new engine in place by the end of next week and I'll re-check that compression again.
Thanks,
Rusty

Hi Everyone and welcome to all of you 4 Barrel Chevy Lovers. ChevyBill has already introduced himself and 490Jim recently ran a Famous Chevy Club and needs no introduction, He is also VCCA TA for 1923-24 Superior Chevys. I provide TA Services for Gearboxes and other mechanical stuff. Since the above postings I have received and replied to several e-mails and would like to share the following summary. I have taken measurements on a spare 28 Engine and the modified engine in my 28 Roadster and also dug out the article by Colin Taylor Evans in the July 1998 G&D Speed and Sport. I ran sample cases based on the horsepower equation presented therein but simplified them as much as possible.
It has been reported that the std. EGGE piston is 1/8 in taller than original and a 6.8 to 1 compression piston might soon be available. I talked to one 28 owner that is using Monroe Rods but as Old George used to say you cant get that kind any more. Below is a summary based on the simplified equations - Comp Ratio = Stroke+Comp Height / Comp Height and - HP = .056 x Cu In x CR, using a 0.075 in Head Gasket, 2800 RPM, 1.06 Volumetric Efficiency and Standard Atmospheric Conditions. I tried to line up the columns but Bill Gates strikes again.

Standard 28 Engine -----171 CI 4.0 CR 38 HP
EGGE Pistons .060 over---174 CI 4.7 CR 45 HP
ModelA Pistons and Rods--188 CI 4.7 CR 49 HP
Monroe Rods -------------171 CI 5.8 CR 55 HP
High Comp Pistons -------171 CI 6.8 CR 65 HP
Special Long Rods -------171 CI 8.5 CR 81 HP

I'll try to add particulars on high comp pistons and long rods as they become available. Some might question how the above configurations square with the VCCA Position regarding modified cars. I would refer you to the Oct 1998 G&D Speed and Sport Page 12.

If you would like to dig further into the above numbers e-mail me at herb@cybersurfers.net

Regards and Happy Holidays
Herb Jackson

[ December 21, 2001: Message edited by: Herb ]

[ December 21, 2001: Message edited by: Herb ]

Herb,
Thanks for the how-to info on increased 4 banger HP. Do you or any one else have comments / experience on how the increased HP effects other componets of the engine (i.e. crank shaft) and what can be done about it??

Also how about: 1. head bolts that are soft to begin with and there are only 8? What torque do you use?. 2. Cam lift? Any interference? 3. Valve size and carb jets for increased hp? 4. Will the head take the extra stress?

Yes Bill and we can cover this in future discussions. RustyFenderand I have exchanged emails and comments in the old forum along with others for years. This Holiday He is installing his new 28 engine with a fully counterweighted and balanced H&H crankshaft. This has very close to an original oiling system and I believe will be adequate for club tours and trips at modern freeway speeds. I hope he will put the pictures he sent me on line so the rest of you can see.
Regards - Herb

Hi CC
1. Were stuck with 8 fasteners but much can be accomplished. I presently have two sets of tool steel studs ( good for tours, not shows ) ready to heat treat. I could not wait and pulled 70 ft lbs on one of my many rejects. More to come.

2. My vintage 3/4 Race 1948 Weber cam has 1/2 in lift and the valves have plenty of room. The problems will arise when we find those 8 to 1 rods.

3. Lots of room for future discussions here. Id like a 2 in intake valve but I cant figure how to locate it. 3a. But officer I was just trying out a new set of jets ! Yeh right, It never worked for me.

4. I always thought so until I read the Rufi letters. He blew the end of the head out with his 13 to 1 Liberty rods. Wrong jets can cause detonation.

These answers are deliberately short guys but theres a lot of good topics here we can cover this winter.
Regards
Herb

Boy did I ever open a can of worms. :eek: