| View previous topic :: View next topic |
| Author |
Message |
poorsha924
Joined: 13 Nov 2007
Posts: 143
Location: Kansas City Mo
|
 Posted: Fri Aug 27, 2010 8:38 pm Post subject: Is a 924 turbo a interference motor? |
 |
|
Hi
I have a chance to pick up a 1980 924 turbo cheap. It has a broken timing belt. I know the 924 N/A is not a interference engine is the same true for the 924 turbo?
thanks
Steve ")
_________________
79 924S snailshell
audi big bore t-body
16" turbo wheels |
|
| Back to top |
|
 |
morghen
Joined: 21 Jan 2005
Posts: 9095
Location: Romania
|
| Posted: Fri Aug 27, 2010 9:07 pm Post subject: |
|
|
931 is an interFEAReance engine
_________________
Supercharger and EFI kits
https://www.the924.com |
|
| Back to top |
|
|
gegge
Joined: 27 Jul 2007
Posts: 1124
Location: Sweden
|
| Posted: Sat Aug 28, 2010 1:13 am Post subject: |
|
|
Not with VW flat-tops and 142,5mm rods and I even got a high-lift cam 
NO FEAR!
_________________
Carl Fredrik Torkildsen
924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs |
|
| Back to top |
|
|
fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
|
| Posted: Sat Aug 28, 2010 3:08 am Post subject: |
|
|
Yep. Bent valves = headgasket, valves, etc.
Pick up some larger valves and make a little more power 
_________________
Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
|
| Back to top |
|
|
morghen
Joined: 21 Jan 2005
Posts: 9095
Location: Romania
|
| Posted: Sat Aug 28, 2010 4:14 am Post subject: |
|
|
| gegge wrote: | Not with VW flat-tops and 142,5mm rods and I even got a high-lift cam
NO FEAR! |
are the VW flattops expensive? i'm begining a rebuild on my other motor and i'm wondering what pistons to use.
_________________
Supercharger and EFI kits
https://www.the924.com |
|
| Back to top |
|
|
gegge
Joined: 27 Jul 2007
Posts: 1124
Location: Sweden
|
| Posted: Sat Aug 28, 2010 6:40 am Post subject: |
|
|
| morghen wrote: | | gegge wrote: | Not with VW flat-tops and 142,5mm rods and I even got a high-lift cam
NO FEAR! |
are the VW flattops expensive? i'm begining a rebuild on my other motor and i'm wondering what pistons to use. |
Forged Mahles are rediculus cheap! Not optimal in therms of combustion efficiency, but got some advantages like super strong and non interference.
Best performance with dished non-interference pistons? Ask ideola!
_________________
Carl Fredrik Torkildsen
924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs |
|
| Back to top |
|
|
flosho
Joined: 01 Jul 2004
Posts: 3160
Location: Eau Claire, Wisconsin
|
| Posted: Sat Aug 28, 2010 7:12 am Post subject: |
|
|
I didn't know all it takes is VW flat tops (can we get these coated and beefed up too?) plus 142.5mm rods and we are interference free!!!
_________________
[This Space For Rent] |
|
| Back to top |
|
|
morghen
Joined: 21 Jan 2005
Posts: 9095
Location: Romania
|
| Posted: Sat Aug 28, 2010 7:47 am Post subject: |
|
|
924 turbo, high performance engine...no interference....sounds perfect !
where can we get quotes for those pistons?
_________________
Supercharger and EFI kits
https://www.the924.com |
|
| Back to top |
|
|
flosho
Joined: 01 Jul 2004
Posts: 3160
Location: Eau Claire, Wisconsin
|
| Posted: Sat Aug 28, 2010 9:06 am Post subject: |
|
|
Does Dan sell em?
_________________
[This Space For Rent] |
|
| Back to top |
|
|
Rasta Monsta
Joined: 12 Jul 2006
Posts: 11733
Location: PacNW
|
| Posted: Sat Aug 28, 2010 9:20 am Post subject: |
|
|
| flosho wrote: | | VW flat tops plus 142.5mm rods and we are interference free!!! |
It could be my pea brain acting up again, but I'm having a hard time seeing how this is possible while maintaining the same compression.
_________________
Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
|
|
| Back to top |
|
|
fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
|
| Posted: Sat Aug 28, 2010 9:30 am Post subject: |
|
|
rods are shorter?
_________________
Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
|
| Back to top |
|
|
ideola
Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI
|
| Posted: Sat Aug 28, 2010 9:34 am Post subject: |
|
|
| Rasta Monsta wrote: | | flosho wrote: | | VW flat tops plus 142.5mm rods and we are interference free!!! |
It could be my pea brain acting up again, but I'm having a hard time seeing how this is possible while maintaining the same compression. |
Easy. The 931 piston has a dish in it. By using a flat top and toying with the pin height plus rod length, you can make up the volume in the combustion chamber, and lower the top of the piston. The OEM pistons have a dish that is approximately 15-16mm deep, have about a 10mm lip all the way around and have steep sides to the dish. The Diamond versions I've commissioned have about 8mm deep dish, about a 5mm lip all the way around and have shallower sides to the dish.
The OEM piston is designed with 0 piston-to-deck clearance, meaning that the lip portion of the pistons sits flush with the deck at TDC. By eliminating the dish and dropping the piston crown further into the bore, you still have volume in the piston, but you also end up with some clearance from the piston crown to the deck. Voilą. Non-interference.
_________________
erstwhile owner of just about every 924 variant ever made |
|
| Back to top |
|
|
Rasta Monsta
Joined: 12 Jul 2006
Posts: 11733
Location: PacNW
|
| Posted: Sat Aug 28, 2010 9:39 am Post subject: |
|
|
Yep, over my head.
So, you've spun one of your Diamond motors with a cam installed and verified clearance?
_________________
Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
|
|
| Back to top |
|
|
fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
|
| Posted: Sat Aug 28, 2010 9:56 am Post subject: |
|
|
Wouldn't that make more of the cylinder bore part of the combustion chamber?
Wonder if that would cause any problems long term?
_________________
Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
|
| Back to top |
|
|
ideola
Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI
|
| Posted: Sat Aug 28, 2010 11:10 am Post subject: |
|
|
| Rasta Monsta wrote: | Yep, over my head.
So, you've spun one of your Diamond motors with a cam installed and verified clearance? |
Yes.
_________________
erstwhile owner of just about every 924 variant ever made |
|
| Back to top |
|
|
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
924 FAQ (Technical)
