What CR are you running

[quickt]

Looking for good feeback from guys who have played with CR ratio on thier Stage 2. Not looking for theory just want to hear from the guys who have used different CR ratios and what their results were.

[Lee Thompson]

8.3 to 1----- 3.600 crank---- 6.5 rods---With J&E's that puts the wrist pin in the oil ring. Use a support ring. With a .520 lift roller, no need to notch the top of pistons for valve relief. That's all I know about that!! That all I know--- period.

What do you have in the works Lonnie?

[quickt]

I am building a 272 stage 2 with stage 2 heads. 3.590 stroke, 6.5 rods. Just looking for some CR info as I need to order pistons. I have noticed that there are some guys running 88 turbo and like 9 to 1 and can only get say 35 or 37 lb of boost out of that combo. I am wondering if maybe going to 10 to 1 might make better use of the boost as it would raise the cyl pressure. Just thinking out loud.

[Lee Thompson]

And I get nervous seeing anything over 25 PSI. Maybe that why I don/t break a lot, not pushing it hard enough.

[Taffy]

Boost is our friend.

[turbodave231]

Lonnie,

I am building a motor that sounds real close to the one you described. S2 with S2 heads, 6.5 rod, 3.590 stroke, 4.000" bore.

I am shooting for 8.0:1 to 8.5:1 CR. I'll know exactly when I've decked the block and made sure I have valve clearance. My heads have 57cc chambers (ASA) and a 39cc dish in the piston. The pin is into the oil ring. What cam and turbo are you going to run?

Dave

[ijames]

Lonnie, back in '99 Bill A had this to say on the gnttypelist:

From: EightSecV6@aol.com
Date: Wed, 6 Oct 1999 23:52:47 EDT
Subject: Re: static compression vs.boost

Hi All,
Just thought I'd share my experience with this subject. I currently have
10:1 compression in my stage 2 that has propelled my 3210# GN to an 8.37 at
165 on 25-26 pounds of boost. My reason for doing this is spool up time. I
run 2 TE63 4 bolt .81 Tang. hsg. turbos on my 278" engine. I can bring the
boost to wherever I want it immediately. My boost gauge moves almost as fast
as my tach! I know there are others who can run a quicker ET with lower
compression but cant win a race. If you mat your accelerator to the floor and
have to count to 3 before your boost us up enough to leave...you've already
lost!
It all depends on what you want to use the car for, if you want to run your
personal best record on every pass you make and dont care how long the green
bulb stays lit before you move, definately go with the low comp. and high
boost. Everyone has their own way of doing things and none of them are wrong.

Sincerely,
Bill Anderson
PS I have run compression to as high as 10.3 with no adverse effects.


I also remember another post he made saying that he had gone through three major engine builds and each time he had raised the cr at least one point, from 8 to 9+ to 10+, but I couldn't find that one.

[qwknuf6]

I have around 8.3 to 1 on my 271 cu in mtr , feels like a stocker, I wonder how 9.5 or 10 to 1 would be like , when I rebuild I think I will go with more comp.

I know I need to run 30 psi now to get the most out of my combo

[quickt]

[quote]Originally posted by turbodave231
Lonnie,

I am building a motor that sounds real close to the one you described. S2 with S2 heads, 6.5 rod, 3.590 stroke, 4.000" bore.

I am shooting for 8.0:1 to 8.5:1 CR. I'll know exactly when I've decked the block and made sure I have valve clearance. My heads have 57cc chambers (ASA) and a 39cc dish in the piston. The pin is into the oil ring. What cam and turbo are you going to run?

Dave [/QUOTE

I am going to run a PTE-88 and the cam will be a solid roller 244/244 .670 lift some where in that range anyway. I am thinking that if an 88 will only go 35 psi with no wastegate with 9.0 then would it make more power with 10.0 and 35psi. I think that it will.

[750H.P.V6]

Lonnie,

I just finished up a new build up on my Stage II motor and upped the compression from 8:1 to 9:1. I had a few concerns to start with since the car is used on the street and I have to run the crappy 91 octane gas we have here in CA.

So far I haven't seen a down side and the extra point of compression doesn't seem to have a real impact on the octane needs of the engine. No track results but on the street with low timing and 15 psi boost the car is nothing short of ruthless.

Pump up the static compression I think you'll like it.

Neal

Lonnie,
call Conley. He might have the most knowledge of anyone running alot of compression in turbo motors. He was running 10:1 compression back in the mid 90s with Tweaked.


hth

Frank

[Lee Thompson]

Here's a thought. 13-1 cr---40 psi--methanol
I talked to a guy at the PRI show with some kind of ricer--tubbed--tube chassis-- inline 6-- rear wheel drive. He had a waste can size turbo. Told me he could run 24 psi with 12-1 cr and methanol, and was planning on going up in boost.

[John Wilde]

Precision has built several Buick Motors with high compression.
Including Conley, Alan Witter and some more secret.

One of Alan's motors had around 10-1 with a 90mm turbo

[EightSecV6]

We generally dont run high boost and like the quick spool of the high compression. My last engine made about 1200hp on 25-26psi, it was an off center using a stock oil pump, the compression was 10.3:1
I am currently using a BIG single but now I have a stick so I am not concerned about the spool and I am using a liquid intercooler so I plan on running the boost up to about 30# on the current engine, the compression is 9:1
On the last engine we did for Alan Witter, we used 9.8:1, he ran at 25-26 psi and went 8.70's in NMCA LS trim. His current engine is underway right now at the shop and it is 9.5:1. He uses a BIG single and benefits from the extra compression on the starting line.
I am not 100% sure on the Precision engine Alan has (he switches from one to the other as they need freshening) we disassembled it once and I am pretty sure we measured it at 10:1.
Bill ANderson

[John Wilde]

Aunt Bethony,

Please let me know more about your car and alan's when you get a chance. I am glad he did not sell his. =)

[quickt]

Originally posted by LikeMy6
Lonnie,
call Conley. He might have the most knowledge of anyone running alot of compression in turbo motors. He was running 10:1 compression back in the mid 90s with Tweaked.


hth

Frank

I talked to Conley. He said that 9.0 to 10.0 is what he runs. Said he ran 10.9 in black.

[TTChevelle]

Lonnie I have a stage 2 motor and stage 2 heads my CR is 8.0-1 it made 1032 rwhp its a twin turbo 276 ci went 8.60@161 on a 29.5 non W at 3620lbs I hope this helps

[TURBOKID]

i have run a 88 and a 91 with 9:1cr. the 88 is race ready on the tree the 91 is not there yet but should be soon.

[John Wilde]

Richie,

I heard some of your stuff is at Precision.
What are you and harry up to???

What are your best times to date?

Thanks in advance

[TURBOKID]

yes some of the stuff was at pte but it is with dan and jim.
my best times were coming at the end of the year after I started getting a handle on the rear end.

1.26- 1.28's
5.321 1/8 mile@ 137. mph
I ran 1/4 in bristol and that was the only time this year.
It ran 8.32@167

then two weeks later I had a 28 inch tire race at the rock on sunday and went down to test on sat. and the car was running a .32 and .34 in the 1/8 and on the 34 pass I tried to run it out the back door like a dummy and floated the valves hard at the 1000ft mark and ran a 8.34@152mph. So Im not sure what it would have run down home in the 1/4. Oh and by the way I had to pedal the car at bristol every pass but the last one to get it to come back to earth. I normaly dont get to run on tracks around here that hooked as hard has bristol, and it took awhile to get the front end under control.

[quickt]

Turbokid what gears do you run in your car? What cam? Please help with some info as i am in the building process.