# What compression ratio for turbo charged VR6?



## vee_are_six (Dec 12, 2002)

Just wondering what the ideal compresion ratio would be for a turbo VR6. Initially I plan to run ~10psi, but want to be able to go bigger down the road if this matters.


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## C2Motorsports (Nov 25, 2003)

*Re: What compression ratio for turbo charged VR6? (vee_are_six)*

It is widely accepted that the stock 10.0:1 compression is at it's limit at 10 psi.
Running a 9.0:1 Spacer, or low CR pistons would enable upwards of 12-14 psi
Yet again, a 8.5:1 Spacer, or low CR pistons would enable upwards of 16-18 psi
All of the above, of course, are assuming that your fueling and timing is tuned correctly.


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## 50CENT (Sep 15, 2002)

*Re: What compression ratio for turbo charged VR6? (C2Motorsports)*

Actually I know of a VR6 that made over 600wheel with forged pistons and 10:1 comp.
I ran 9:0:1 with 18psi with FMU and 
8:5:1 with 25psi with DTA. Both with the same stock bottom end which started its boosted journey in 2001 and is still assembled.
You cant really go by boost cause diff people run diff turbos and such. You need to pick a HP and go off that, then whatever boost you need to run to make that hp then thats were you stop. Its definetly safe to say that a Bone stock vr will hold over 300whp for a while without having gasket problems. But if you put headbolts and headgasket right away then you will find yourself upgrading your fuel system before your engine.


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## 1QUIKVR (Dec 7, 2001)

*Re: What compression ratio for turbo charged VR6? (vee_are_six)*

I have 10:1 at the moment and don't plan on changing it for a while. Holds 10psi just fine. Going to turn it up more this summer.


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## SpinEcho (Oct 12, 2003)

*Re: What compression ratio for turbo charged VR6? (1QUIKVR)*

I still have a lot of trouble with the idea than stock CR can take 10 psi without detonation. It's not that I don't believe some of you guys have done it. I'm just going by my own experience (detonation!) and from what I've read. Corky Bell's publications have included rough estimates for limits of boost at given CR's, with accompanying graphs, and they suggest 10 psi on 10:1 is a real stretch.


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## nycvr6 (May 4, 1999)

*Re: What compression ratio for turbo charged VR6? (SpinEcho)*


_Quote, originally posted by *SpinEcho* »_I still have a lot of trouble with the idea than stock CR can take 10 psi without detonation. It's not that I don't believe some of you guys have done it. I'm just going by my own experience (detonation!) and from what I've read. Corky Bell's publications have included rough estimates for limits of boost at given CR's, with accompanying graphs, and they suggest 10 psi on 10:1 is a real stretch.

Books like Bell's are basically guidelines, it is not etched in stone. A lot has to do with the specific motor, whether fuel can be supplied, etc... http://****************.com/smile/emthup.gif


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## Holy Piston (Oct 24, 2003)

*Re: What compression ratio for turbo charged VR6? (nycvr6)*

50CENT,how much HP is a 60-1 HIFI in VR capable of ? What are the #'s you have seen from this turbo?


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## 1QUIKVR (Dec 7, 2001)

*Re: What compression ratio for turbo charged VR6? (SpinEcho)*


_Quote, originally posted by *SpinEcho* »_I still have a lot of trouble with the idea than stock CR can take 10 psi without detonation. It's not that I don't believe some of you guys have done it. I'm just going by my own experience (detonation!) and from what I've read. Corky Bell's publications have included rough estimates for limits of boost at given CR's, with accompanying graphs, and they suggest 10 psi on 10:1 is a real stretch.

I didn't experiance any detonation at all. Maybe it's a fluke? I don't know. It works though.


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## 50CENT (Sep 15, 2002)

*Re: What compression ratio for turbo charged VR6? (Holy Piston)*

you should be able to make over 500whp but you will be out of the turbo's eff range


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## Holy Piston (Oct 24, 2003)

*Re: What compression ratio for turbo charged VR6? (50CENT)*

Thanx 50,I wondered what this turbo does in "real life", now I know.


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## vee_are_six (Dec 12, 2002)

*Re: What compression ratio for turbo charged VR6? (Holy Piston)*

Thanks guys. My reasons for asking are that I picked up a set of JE pistons that are 9.5:1 and was wondering how safe I will be. I am planning on running fairly high boost in the future. Do you think this will be low enough compression? Should I maybe do a spacer as well to get the CR down a little lower?


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## 1QUIKVR (Dec 7, 2001)

*Re: What compression ratio for turbo charged VR6? (vee_are_six)*

If you are going to run high boost you may as well go with 8.5:1 off the bat.


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## C2Motorsports (Nov 25, 2003)

*Re: What compression ratio for turbo charged VR6? (vee_are_six)*


_Quote, originally posted by *vee_are_six* »_Thanks guys. My reasons for asking are that I picked up a set of JE pistons that are 9.5:1 and was wondering how safe I will be. I am planning on running fairly high boost in the future. Do you think this will be low enough compression? Should I maybe do a spacer as well to get the CR down a little lower?

Why not run the 9.5:1 JE's with our 9.0:1 SS head spacer, this will bring you down to 8.5:1 http://****************.com/smile/emthup.gif 
Or sell, the 9.5's that you have, and purchase a set of 8.5's....which ever is more cost-effective for you.
Our spacer is ~$219 delivered


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## jsnVR6 (Feb 5, 2001)

C2 has a good point there.
The gasket they have is better than the factory MK3 gasket anyway. Will seal much better.
I will be using their 9:1 spacer with my 9:1 pistons so that I can run 25 - 30 psi.


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## vee_are_six (Dec 12, 2002)

*Re: What compression ratio for turbo charged VR6? (C2Motorsports)*


_Quote, originally posted by *C2Motorsports* »_
Why not run the 9.5:1 JE's with our 9.0:1 SS head spacer, this will bring you down to 8.5:1 http://****************.com/smile/emthup.gif 
Our spacer is ~$219 delivered

Thanks, as of right now that is what I will end up doing. One question though, is the spacer really a good way to go or will this cause more problems than just buying the right pistons?


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## C2Motorsports (Nov 25, 2003)

*Re: What compression ratio for turbo charged VR6? (vee_are_six)*


_Quote, originally posted by *vee_are_six* »_
...... is the spacer really a good way to go or will this cause more problems than just buying the right pistons?

We have many of our SS head spacers out in the field working with GREAT results, so NO this will not cause you any problems.
The advantage to our head spacer is that we utilized the OEM VW metal head gaskets so that we retain a factory-like seal when installed.
We offer an economical solution to lowering your compression that has been manufactured to the highest standards, using the best materials.
This has resulted in many customers successfully running higher boost in their FI cars using our products. 

C2Motorsports


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## SpinEcho (Oct 12, 2003)

*Re: What compression ratio for turbo charged VR6? (vee_are_six)*


_Quote, originally posted by *vee_are_six* »_One question though, is the spacer really a good way to go or will this cause more problems than just buying the right pistons?

Uh...If you are going to buy pistons, isn't it an exercise in self-defeat to add a spacer? Never mind how good quality that spacer might be - do it right the first time if you're going to spend the money! http://****************.com/smile/emthup.gif


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## WMTJ (Jan 26, 2001)

Try 7.5:1. Nice and safe. I'm running that with a 60-1hifi with stand alone and I'll be on the dyno in a couple of weeks. My only regret is the limiting 55lb injectors in the car.
I didn't mean to hijack your thread. Just don't be afraid to lower it. 7.5:1 - 8.5:1 is a good range for a turbo charged VR6 and 93 octane in my opinion.


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## leebro61 (Nov 7, 2001)

*Re: (WMTJ)*

When I ordered my pistons, I was debating 8.5 and 9:1. The guy I spoke with told me that with new technology and decent gas 9:1 was plenty low! He said anything lower would just hurt power, driveability and efficiency. He also mentioned that the strength of the piston would be compromised. Needless to say, he didnt like the 8.5:1.
Then again, HPA does seem to favor stupidly low compression, so who knows. 
I say 9:1 is fine for a street car and good pump gas


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## vee_are_six (Dec 12, 2002)

*Re: What compression ratio for turbo charged VR6? (SpinEcho)*


_Quote, originally posted by *SpinEcho* »_Uh...If you are going to buy pistons, isn't it an exercise in self-defeat to add a spacer? Never mind how good quality that spacer might be - do it right the first time if you're going to spend the money! http://****************.com/smile/emthup.gif 

I agree, but I picked these pistons up for next to nothing. I didn't have a say in compression.
Thanks for all the good info everyone. C2Motorsports, you will be hearing from me soon http://****************.com/smile/emthup.gif 
Here's another question that some of you have brought up. What do you guys think is the most boost you dare run on pump gas?


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## climbingcue (Feb 2, 2001)

*Re: What compression ratio for turbo charged VR6? (SpinEcho)*


_Quote, originally posted by *SpinEcho* »_
Uh...If you are going to buy pistons, isn't it an exercise in self-defeat to add a spacer? Never mind how good quality that spacer might be - do it right the first time if you're going to spend the money! http://****************.com/smile/emthup.gif 

You will need a good headgasket anyway, and the one like C2 has will hold more boost than a stock one, plus it is 1 million times better than using a copper headgasket...


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## leebro61 (Nov 7, 2001)

*Re: What compression ratio for turbo charged VR6? (climbingcue)*

Does anybody make a stock compression metal headgasket for somebody who already has lower comp pistons?


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## benzivr6 (Feb 16, 2001)

*Re: What compression ratio for turbo charged VR6? (leebro61)*


_Quote, originally posted by *leebro61* »_Does anybody make a stock compression metal headgasket for somebody who already has lower comp pistons?








 
I had the idea of buying 2 MK4 HDG take 1 MK4 HDG apart put the middle sleeve in the other MK4 HDG slap the 4 pieces 2gether and hopefully rivet it back to specs? I just a suggestion suppplied Homedepotmotorsports style


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## leebro61 (Nov 7, 2001)

*Re: What compression ratio for turbo charged VR6? (benzivr6)*

Ill check with schimmel, I think I might have saw one on his site at some point.
Cough Cough c2 get to work Cough Cough







hehe


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## C2Motorsports (Nov 25, 2003)

*Re: What compression ratio for turbo charged VR6? (benzivr6)*


_Quote, originally posted by *benzivr6* »_ 
I had the idea of buying 2 MK4 HDG take 1 MK4 HDG apart put the middle sleeve in the other MK4 HDG slap the 4 pieces 2gether and hopefully rivet it back to specs? I just a suggestion suppplied Homedepotmotorsports style









If you want the center pieces, just let me know....we throw piles of them away all the time


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## 50CENT (Sep 15, 2002)

*Re: What compression ratio for turbo charged VR6? (vee_are_six)*


_Quote, originally posted by *vee_are_six* »_

Here's another question that some of you have brought up. What do you guys think is the most boost you dare run on pump gas?

Not boost but power. Most cars make around 450whp on pump and thats pushin it


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## 50CENT (Sep 15, 2002)

*Re: What compression ratio for turbo charged VR6? (leebro61)*


_Quote, originally posted by *leebro61* »_Ill check with schimmel, I think I might have saw one on his site at some point.
Cough Cough c2 get to work Cough Cough







hehe









Schimmel does make them in diff sizes


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## C2Motorsports (Nov 25, 2003)

*Re: What compression ratio for turbo charged VR6? (leebro61)*


_Quote, originally posted by *leebro61* »_Ill check with schimmel, I think I might have saw one on his site at some point.
Cough Cough c2 get to work Cough Cough







hehe









Once you get your throat clear, tell me what size you want


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## WMTJ (Jan 26, 2001)

My 7.5:1 compression ratio is an experiment. I'd like to see what the power curve looks like on a dyno. My main reason for so low a compression ratio is so I can run in the 20-25 psi range with 93octane.
It'll happen. 
As for it being to low. Nonsense. My VR6's fuel curve is running very rich in the lower RPMs and I was getting 5psi around 2800rpms and off boost it felt very close to a NA VR6. When I lean it out down low to spool the turbo up a little faster we'll see how that curve looks.
Bottom line..... do your own experimenting. Don't let anyone discourage you form trying something different because they don't "think" it will work.


_Modified by WMTJ at 10:08 PM 1-31-2004_


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## leebro61 (Nov 7, 2001)

*Re: (WMTJ)*


_Quote, originally posted by *WMTJ* »_My 7.5:1 compression ratio is an experiment. I'd like to see what the power curve looks like on a dyno. My main reason for so low a compression ratio is so I can run in the 20-25 psi range with 93octane.
It'll happen. 
As for it being to low. Nonsense. My VR6's fuel curve is running very rich in the lower RPMs and I was getting 5psi around 2800rpms and off boost it felt very close to a NA VR6. When I lean it out down low to spool the turbo up a little faster we'll see how that curve looks.
Bottom line..... do your own experimenting. Don't let anyone discourage you form trying something different because they don't "think" it will work.

_Modified by WMTJ at 10:08 PM 1-31-2004_

I wasnt knocking you, Im just saying based on all modern boosted cars that I see, there is no reason IMO to go that low. Tell ya what, Im moving down to Daytona Beach next year and we will meet up and see what the difference is off boost and such








Chris, I was looking for a stock compression headgasket for stock bore, I have pistons to drop my comp, just wanting a bit beefier of a gasket.
Lee http://****************.com/smile/emthup.gif


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## C2Motorsports (Nov 25, 2003)

*Re: (leebro61)*


_Quote, originally posted by *leebro61* »_
Chris, I was looking for a stock compression headgasket for stock bore, I have pistons to drop my comp, just wanting a bit beefier of a gasket.
Lee http://****************.com/smile/emthup.gif 

why not use an MKIV VR6 metal gasket ?


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## keinreis (Dec 5, 2002)

*Re: What compression ratio for turbo charged VR6? (SpinEcho)*


_Quote, originally posted by *SpinEcho* »_I still have a lot of trouble with the idea than stock CR can take 10 psi without detonation. It's not that I don't believe some of you guys have done it. I'm just going by my own experience (detonation!) and from what I've read. Corky Bell's publications have included rough estimates for limits of boost at given CR's, with accompanying graphs, and they suggest 10 psi on 10:1 is a real stretch.

I know I don't have a vr, but My 16v is running 10 psi with no detonation and compression on that is 10.58:1


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## leebro61 (Nov 7, 2001)

*Re: (C2Motorsports)*


_Quote, originally posted by *C2Motorsports* »_
why not use an MKIV VR6 metal gasket ?

mk4 gasket is thinner and would raise my 9:1 compression to ~9.5:1 right?
If changing to an mk4 gasket raises compression on an NA motor, Id assume it would do the same on a turbo motor.


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## C2Motorsports (Nov 25, 2003)

*Re: (leebro61)*


_Quote, originally posted by *leebro61* »_
mk4 gasket is thinner and would raise my 9:1 compression to ~9.5:1 right?
If changing to an mk4 gasket raises compression on an NA motor, Id assume it would do the same on a turbo motor.









Tell you what, I have a prototype spacer, that would retain your 9:1 CR...if you would like to try it????
Email me: [email protected]


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## StreetRyda (Nov 23, 2002)

Im looking for safe 350+ WHP on a MK4 VR6 what compresion should run with?


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## C2Motorsports (Nov 25, 2003)

*Re: (StreetRyda)*

I would suggest dropping your compression to 9:1, either with our SS laser cut spacer ($219), or low CR pistons.


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## 1SlowSLC (May 4, 2003)

I have a copper gasket that is stock size sandwiched between the mk4 gaskets outer pieces. Its working fine on my car so far,, but its still not tuned or running boost tubes yet. The same setup has worked on another 500+ whp car also.
Oh my setup is @8.5:1 comp, done thru 8.5:1 JE's and that gasket.


_Modified by 1SlowSLC at 12:52 AM 2-8-2004_


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## C2Motorsports (Nov 25, 2003)

*Re: (1SlowSLC)*


_Quote, originally posted by *1SlowSLC* »_I have a copper gasket that is stock size sandwiched between the mk4 gaskets outer pieces. Its working fine on my car so far,, but its still not tuned or running boost tubes yet. The same setup has worked on another 500+ whp car also.


Out of curiosity what 'other' +500hp car is successfully running that setup?
chris
C2


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## 1SlowSLC (May 4, 2003)

Well it was Chris Green who was running that.......but now I have to put my foot in my mouth cuz he blew his gasket. But that gasket blew when he was making dyno pulls in the 550whp range.


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## 1SlowSLC (May 4, 2003)

Ill just run mine till it pops, then go to the steel setup like Chris and everyone else is doing, we have a local guy in florida who makes the center piece also, http://www.porttuning.com is the place.


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## C2Motorsports (Nov 25, 2003)

*Re: (1SlowSLC)*


_Quote, originally posted by *1SlowSLC* »_Well it was Chris Green who was running that.......but now I have to put my foot in my mouth cuz he blew his gasket. But that gasket blew when he was making dyno pulls in the 550whp range.

...........ask Chris who's spacer he is running now







......

_Quote, originally posted by *1SlowSLC* »_Ill just run mine till it pops, then go to the steel setup like Chris and everyone else is doing..........

I think that is a *GREAT* idea...call me when you are ready to install one...I have the 9.0:1($199) and the 8.5:1($225) SS spacers in stock.......



_Modified by C2Motorsports at 6:25 PM 3-14-2004_


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## 1SlowSLC (May 4, 2003)

I need a spacer that will keep my compression at 8.5:1...I have pistons already so I need stock thickness


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## turbomatic (Apr 18, 2004)

*Re:*

what do you do with th valve timing when using a gasket?
It will be different and the tension also.


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## 1QUIKVR (Dec 7, 2001)

*Re: Re: (turbomatic)*

I had that question as well but no one seems to have any problems with it. 

_Quote, originally posted by *turbomatic* »_what do you do with th valve timing when using a gasket?
It will be different and the tension also.


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## Holy Piston (Oct 24, 2003)

*Re: Re: (1QUIKVR)*

I thought about that too,and called the man himself,Bill Schimmel,and he was cool enough to take his time and explain to me that it was no big deal,and he runs them with spacers all the time,no problem.After that I didn't worry about it,but I noticed the motor boosts really early,maybe it is the 60-1hi-fi,but the car came on fast,so responsive,so maybe the advanced cams helped that bottom-mid range.......







next motor is Mk4 gasket,and it will be interesting to see if there is a "shift in the powerband"with the cams set back to stock timing with same setup......I will report my findings!!







http://****************.com/smile/emthup.gif


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## JettaGLXdriver (Oct 3, 2002)

2.845844:1


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