Notices
944 Turbo and Turbo-S Forum 1982-1991
Sponsored by:
Sponsored by: Clore Automotive

head Combustion volume 951 2V vs 968. who knows?

Thread Tools
 
Search this Thread
 
Old 11-05-2008, 08:52 PM
  #1  
95ONE
Race Car
Thread Starter
 
95ONE's Avatar
 
Join Date: Sep 2005
Location: TEXAS
Posts: 4,247
Likes: 0
Received 0 Likes on 0 Posts
Default head Combustion volume 951 2V vs 968. who knows?

Getting ahead start on this.

Anyone know the cc (volume) of the 2v 951 head and the cc of the 4 valve 968 head?

Gotta get some custom pistons made. Probably from a Chevy slug.

Last edited by 95ONE; 11-05-2008 at 10:25 PM.
Old 11-05-2008, 09:47 PM
  #2  
gt37vgt
Drifting
 
gt37vgt's Avatar
 
Join Date: May 2006
Location: Melbourne
Posts: 3,481
Likes: 0
Received 0 Likes on 0 Posts
Default

volume not area .
surly if you are running E85 your not fussy about compression ratios ?
are you putting a 968 head on ?
Old 11-05-2008, 10:29 PM
  #3  
95ONE
Race Car
Thread Starter
 
95ONE's Avatar
 
Join Date: Sep 2005
Location: TEXAS
Posts: 4,247
Likes: 0
Received 0 Likes on 0 Posts
Default

Not being fussy. Trying to KEEP the higher compression ratio. I have to have a custom Piston made for a high compression turbo motor. Not too many people asking for both of those at the same time.
there's the 968 Turbo piston that lowers compression for the 3.0 liter. Then de-stroke that to 2.5 and you get even less compression. NOT the direction I need. Forged NA 968 pistons won't do. Not enough meat above the wrist pin, or too short piston skirt, the common flaw of turbo-ing the stock 3.0 liter. Forged piston, but it won't handle the boost.
Old 11-05-2008, 10:42 PM
  #4  
TurboCab
Racer
 
TurboCab's Avatar
 
Join Date: Sep 2003
Location: Puerto Rico
Posts: 322
Likes: 0
Received 3 Likes on 3 Posts
Default

951 Head = 55cc Aprox.
968 Head = 41cc Aprox.
Hope this help.
Old 11-05-2008, 10:46 PM
  #5  
Mike Lindsey
Basic Sponsor
Rennlist
Site Sponsor

 
Mike Lindsey's Avatar
 
Join Date: Nov 2003
Posts: 791
Likes: 0
Received 7 Likes on 4 Posts
Default

951 heads range from 56 to 62cc.
__________________
Mike or Dave Lindsey
www.lindseyracing.com
U.S. 1-877-943-3565
Other 1-405-947-0137
Old 11-05-2008, 11:24 PM
  #6  
TonyG
Rennlist Junkie Forever
 
TonyG's Avatar
 
Join Date: Dec 2001
Location: Los Angeles
Posts: 5,978
Likes: 0
Received 2 Likes on 2 Posts
Default

Originally Posted by 95ONE
there's the 968 Turbo piston that lowers compression for the 3.0 liter. Then de-stroke that to 2.5 and you get even less compression.
Using a 2.5L crank with a 968T piston in a down-sleeved 968 block would be an extremely poor approach to lowering the static compression since the piston would be sitting down in the hole 4.55mm at TDC + the compressed thickness of the head gasket.


TonyG
Old 11-05-2008, 11:29 PM
  #7  
Lorax
The Impaler
Rennlist Member
 
Lorax's Avatar
 
Join Date: Jan 2006
Location: North Georgia
Posts: 13,696
Likes: 0
Received 1 Like on 1 Post
Default

Originally Posted by TonyG
Using a 2.5L crank with a 968T piston in a down-sleeved 968 block would be an extremely poor approach to lowering the static compression since the piston would be sitting down in the hole 4.55mm at TDC + the compressed thickness of the head gasket.


TonyG
I don't think he is trying to lower it if I read correctly.
Old 11-05-2008, 11:31 PM
  #8  
TonyG
Rennlist Junkie Forever
 
TonyG's Avatar
 
Join Date: Dec 2001
Location: Los Angeles
Posts: 5,978
Likes: 0
Received 2 Likes on 2 Posts
Default

Originally Posted by Lorax
I don't think he is trying to lower it if I read correctly.
Ahhh... sorry, you're correct. My bad.


TG
Old 11-06-2008, 12:17 AM
  #9  
333pg333
Rennlist Member
 
333pg333's Avatar
 
Join Date: Feb 2006
Location: Australia
Posts: 18,902
Received 93 Likes on 76 Posts
Default

What sort of c/r are you aiming at Bruce? Also what sort of boost are you intending to use?
Old 11-06-2008, 01:11 AM
  #10  
95ONE
Race Car
Thread Starter
 
95ONE's Avatar
 
Join Date: Sep 2005
Location: TEXAS
Posts: 4,247
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by TurboCab
951 Head = 55cc Aprox.
968 Head = 41cc Aprox.
Hope this help.
Good news. Thanks.

Originally Posted by Mike Lindsey
951 heads range from 56 to 62cc.
thank you. Any suggestions for me?

Originally Posted by Lorax
I don't think he is trying to lower it if I read correctly.
Correct. Not lower.. Raise!
Old 11-06-2008, 01:12 AM
  #11  
95ONE
Race Car
Thread Starter
 
95ONE's Avatar
 
Join Date: Sep 2005
Location: TEXAS
Posts: 4,247
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by 333pg333
What sort of c/r are you aiming at Bruce? Also what sort of boost are you intending to use?
As close to 11:1 as I can get. Will be running between 15 and 20 lbs of boost.
Old 11-06-2008, 02:19 AM
  #12  
TonyG
Rennlist Junkie Forever
 
TonyG's Avatar
 
Join Date: Dec 2001
Location: Los Angeles
Posts: 5,978
Likes: 0
Received 2 Likes on 2 Posts
Default

sleeve the engine and run a conventional aftermarket style piston which you can have configured to your specifications.


TonyG
Old 11-06-2008, 11:24 AM
  #13  
blown 944
Race Car
 
blown 944's Avatar
 
Join Date: Jul 2007
Location: Firestone, Colorado
Posts: 4,826
Likes: 0
Received 4 Likes on 4 Posts
Default

Bruce .... You and I really are on the same page. High compression turbo engine .

Haven't looked at it too much yet myself, but while doing this maybe you can get a longer rod in there too. Especially since you will be most likely looking at custom slugs.

I wonder though, how much the offset pin (stock design) will change things.

That put me on hold when I was initially looking at "Chevying" my engine... then big boost happened and ...well you know .
Old 11-06-2008, 12:08 PM
  #14  
porshhhh951
Monkeys Removed by Request
Lifetime Rennlist
Member
 
porshhhh951's Avatar
 
Join Date: Feb 2003
Location: New York
Posts: 7,713
Likes: 0
Received 1 Like on 1 Post
Default

Originally Posted by blown 944
Bruce .... You and I really are on the same page. High compression turbo engine .

Haven't looked at it too much yet myself, but while doing this maybe you can get a longer rod in there too. Especially since you will be most likely looking at custom slugs.

I wonder though, how much the offset pin (stock design) will change things.

That put me on hold when I was initially looking at "Chevying" my engine... then big boost happened and ...well you know .
will you please get you're *** to a dyno.

Only a handful of guys on this board are running e-85 and i'm dying to see what setups produce what numbers on it.
Old 11-06-2008, 12:45 PM
  #15  
blown 944
Race Car
 
blown 944's Avatar
 
Join Date: Jul 2007
Location: Firestone, Colorado
Posts: 4,826
Likes: 0
Received 4 Likes on 4 Posts
Default

OT Sorry Bruce,

John, If I can find the time I will get there. I really am not too worried about it at this point though for a number of reasons.

1) as of right now I am not optimally setup ie:
a) too big of turbo for the boost I am currently running (graph would look stupid)
b) the head is minimally ported
c) ignition is randomly giving problems at over 23 psi (has been since the engine swap)

2) I've been working on a true twin scroll crossover pipe to use with a smaller turbine housing for quicker spoolup

3) I am just enjoying driving the car and not trying to kill it (If I go to the dyno most likely I would turn it up, just my nature)

4) I am focused on the car in my avatar, if I start fooling with my DD again it will again prolong the progress

5) dyno numbers are only for seeing the gains from last time to me. The correction factors and such leave the door open for disputes. See my last dyno thread and what has never been mentioned about another car's (prominent one) numbers including correction factors. To me, I have realized it's not worth the hassle of defending.


Honestly IMO, I haven't at this time made enough changes to warrant dyno time. Or to put it another way the setup is not exactly where I would like it to be to drive an hr to do it.

I am really just keeping myself in check here.

please excuse the OT


Quick Reply: head Combustion volume 951 2V vs 968. who knows?



All times are GMT -3. The time now is 11:22 PM.