 |
924Board.org
Discussion Forum of 924.org
|
| View previous topic :: View next topic |
| Author |
Message |
safe
Joined: 18 Mar 2017
Posts: 591
Location: Sweden
|
 Posted: Tue Nov 15, 2022 5:59 pm Post subject: |
 |
|
| Mclaren924 wrote: | | safe wrote: | | Mclaren924 wrote: | It's becoming a street drag car. Not popular around here I know but I've never been normal. By full race car I mean one seat, no interior, roll cage, tube chassis front end/ widebody on rear end and some 944 fenders up front for some meaty tires. ECU, E85, turbo the size of my head  the whole 9 yards. |
Yeah, I'm not sure the 924 platform (engine / transmission) is very suited to drag racing. Would be cool to try and see how long it could be taken, but a stock k20 with a cheap turbo is probably capable of more power than a modded 931 engine.
I got a 4-500 hp capable turbo on my NA engine, limited right now by the clutch, but I'm fairly certain it can brake 400 hp with it.
EFI is pretty cool when you start to experiment with launch control (2 step). I got the car to launch with 8-9 psi. Just step of the clutch and it takes of with spinning tires. |
The Ring and pinion ive been told aren't abuse friendly I've been told so it will definitely need some help but I really do plan to push it till it break... I cant help it, its what I did to my Subaru and she went to the moon but died in the process lol. I don't know what drew me to 924's but i've got 4 now so it must be an disease or something lol. |
That is what Subarus do! 
I guess you have a 931 snail shell? I would assume it has the same weakness as the 915, the diffcover is weak and it flexes and then you have a diff failure. Diff cover has the same partnumber between 915 and g31. There are billet covers you can use, but expensive. Alternatively you can mill the cover flat and add a steel plate, about 6-8 mm, on the outside with longer studs.
If the G31 has a 2 part bearing retainer internally, like the 915, there might be a 1 piece retainer that will add strength to gearbox (keeping the to shafts connected better).
I haven't heard that these issues from the 915 is a problem in the G31, the diff cover should be. Maybe the g31 isn't as stressed with only 170 hp (and up to 200 ish modified) and without the rear weight for traction. But I disintegrated the 915 diff in my 911 with tones of auto-x launches and track time with 250+ hp.
Otherwise the g31 should be strong thick input shaft, wide gears. Unfortunately useless syncros for fast shifting...
An intercooler would be step number 1 before touching anything else. From what I have seen pistons melt at anything above stock boost.
If you are making your own EFI, the fuel rail you can make yourself. You buy aluminum fuel rail stock, cut to length, drill holes for the injectors, tap the ends for AN fittings and make some form of attachment (drill,tap,screw probably).
You need adapters for the modern injectors in the manifold, I think injectors with an extended tip suits the 931 as it does in the NA,
_________________
/Magnus, Stockholm Sweden
=======================
Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe |
|
| Back to top |
|
 |
Cedric
Joined: 27 Aug 2004
Posts: 2614
Location: Sweden
|
| Posted: Tue Nov 15, 2022 7:24 pm Post subject: |
|
|
If you arent detonating, or doing anything completely crazy with the timing the stock pistons will not break. Its similar to any old engine with cast pistons, they work until detonation, thats where forged pistons really comes in handy, or for durability over time.
Diff failures arent very common on the G31 boxes, im not sure which box you have though. But they arent normally used for drag racing, i think he 1-2 shift is the biggest issue for that, that shift cant be rushed without long term consequences/repairs.
I know only one active 924 that do drag racing here in sweden, with a v8 in a pretty (for now at least) standard 924.
Check at 10:43
https://youtu.be/U9VEDO_BDkQ
_________________
1980 924 Turbo
www.instagram.com/garagecedric/ |
|
| Back to top |
|
|
safe
Joined: 18 Mar 2017
Posts: 591
Location: Sweden
|
| Posted: Tue Nov 15, 2022 7:51 pm Post subject: |
|
|
| Cedric wrote: |
I know only one active 924 that do drag racing here in sweden, with a v8 in a pretty (for now at least) standard 924.
Check at 10:43
https://youtu.be/U9VEDO_BDkQ |
I wonder if he still has the 924 transmission and torquetube.... a bit too much "stance" and rear camber for dragracing. 
_________________
/Magnus, Stockholm Sweden
=======================
Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe |
|
| Back to top |
|
|
Mclaren924
Joined: 13 Oct 2021
Posts: 171
Location: California
|
| Posted: Wed Nov 16, 2022 1:34 am Post subject: |
|
|
| safe wrote: | | Mclaren924 wrote: | | safe wrote: | | Mclaren924 wrote: | | It's becoming a street drag car. Not popular around here I know but I've never been normal. By full race car I mean one seat, no interior, roll cage, tube chassis front end/ widebody on rear end and some 944 fenders up front for some meaty tires. ECU, E85, turbo the size of my head the whole 9 yards. |
Yeah, I'm not sure the 924 platform (engine / transmission) is very suited to drag racing. Would be cool to try and see how long it could be taken, but a stock k20 with a cheap turbo is probably capable of more power than a modded 931 engine.
I got a 4-500 hp capable turbo on my NA engine, limited right now by the clutch, but I'm fairly certain it can brake 400 hp with it.
EFI is pretty cool when you start to experiment with launch control (2 step). I got the car to launch with 8-9 psi. Just step of the clutch and it takes of with spinning tires. |
The Ring and pinion ive been told aren't abuse friendly I've been told so it will definitely need some help but I really do plan to push it till it break... I cant help it, its what I did to my Subaru and she went to the moon but died in the process lol. I don't know what drew me to 924's but i've got 4 now so it must be an disease or something lol. |
That is what Subarus do!
I guess you have a 931 snail shell? I would assume it has the same weakness as the 915, the diffcover is weak and it flexes and then you have a diff failure. Diff cover has the same partnumber between 915 and g31. There are billet covers you can use, but expensive. Alternatively you can mill the cover flat and add a steel plate, about 6-8 mm, on the outside with longer studs.
If the G31 has a 2 part bearing retainer internally, like the 915, there might be a 1 piece retainer that will add strength to gearbox (keeping the to shafts connected better).
I haven't heard that these issues from the 915 is a problem in the G31, the diff cover should be. Maybe the g31 isn't as stressed with only 170 hp (and up to 200 ish modified) and without the rear weight for traction. But I disintegrated the 915 diff in my 911 with tones of auto-x launches and track time with 250+ hp.
Otherwise the g31 should be strong thick input shaft, wide gears. Unfortunately useless syncros for fast shifting...
An intercooler would be step number 1 before touching anything else. From what I have seen pistons melt at anything above stock boost.
If you are making your own EFI, the fuel rail you can make yourself. You buy aluminum fuel rail stock, cut to length, drill holes for the injectors, tap the ends for AN fittings and make some form of attachment (drill,tap,screw probably).
You need adapters for the modern injectors in the manifold, I think injectors with an extended tip suits the 931 as it does in the NA, |
I know the flex plate can help a lot but what about solid mounts for the transmission as well to stop it from moving as much when launched. Ultimately I foresee gearboxes being my real killer, are the standard 5 speed turbo H pattern out the 80-81 cars any better? I have one laying around I could swap in I just always read people use snailshell so it must be for a reason.
_________________
1980 931 "Salt" Bucket wannabe racer (not started)
1979 924 "Pepper" Restoration (almost done)
1980 924 "Donnie" (Parts car)-DEAD
1977 924 Slicktop "Pennie" Bucket turned Silver Spoon |
|
| Back to top |
|
|
Mclaren924
Joined: 13 Oct 2021
Posts: 171
Location: California
|
| Posted: Wed Nov 16, 2022 1:45 am Post subject: |
|
|
| Cedric wrote: | If you arent detonating, or doing anything completely crazy with the timing the stock pistons will not break. Its similar to any old engine with cast pistons, they work until detonation, thats where forged pistons really comes in handy, or for durability over time.
Diff failures arent very common on the G31 boxes, im not sure which box you have though. But they arent normally used for drag racing, i think he 1-2 shift is the biggest issue for that, that shift cant be rushed without long term consequences/repairs.
I know only one active 924 that do drag racing here in sweden, with a v8 in a pretty (for now at least) standard 924.
Check at 10:43
https://youtu.be/U9VEDO_BDkQ |
I know I said I wasn't trying to do pistons and rods but now you have me interested...What would be my options if I did want to go forged rotating assembly? I know there's an Australian company that makes rods for like 600 usd and then JE pistons said they would do 8 for a 1000$ but what's the possibilities of forged parts in one of these cars? 600hp but its hanging on for dear life? Yeah I paid my price with pulling timing in my subaru getting greedy trying to suck more power that wasn't truly there.
_________________
1980 931 "Salt" Bucket wannabe racer (not started)
1979 924 "Pepper" Restoration (almost done)
1980 924 "Donnie" (Parts car)-DEAD
1977 924 Slicktop "Pennie" Bucket turned Silver Spoon |
|
| Back to top |
|
|
Mike9311
Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish
|
| Posted: Sat Nov 19, 2022 12:39 am Post subject: |
|
|
Safe, you are referring to this cover right?
https://cdn.shopify.com/s/files/1/0592/3957/products/DSC09633_1024x1024.jpeg?v=1438276454
Solid mounts would make the issue worse since the only thing that can now move would be the dif without dealing with the issue
I agree with the shifting comment. You want fast hard shifts especially launching out of "the hole"
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
|
| Back to top |
|
|
safe
Joined: 18 Mar 2017
Posts: 591
Location: Sweden
|
| Posted: Sat Nov 19, 2022 1:18 am Post subject: |
|
|
Yes.
Sucks that there is no image upload, I have an image of my poor mans variant, just a steel plate.
Also have picture of the carnage that can follow, in a 915. Anyone who wants to guess the price for a ring and pinion from Porsche?
_________________
/Magnus, Stockholm Sweden
=======================
Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe |
|
| Back to top |
|
|
Mclaren924
Joined: 13 Oct 2021
Posts: 171
Location: California
|
| Posted: Sat Nov 19, 2022 1:44 am Post subject: |
|
|
| safe wrote: |
Yes.
Sucks that there is no image upload, I have an image of my poor mans variant, just a steel plate.
Also have picture of the carnage that can follow, in a 915. Anyone who wants to guess the price for a ring and pinion from Porsche? |
2 blood lines first born and the American declaration of independence? That sounds like it has transcended 4 figures getting close to 5 lol. Lots of 0's. The fast and hard shifting is exactly how I'll be driving so we'll see how long they last. Can anyone comment on how hard it would be to swap a much later 951, o1e, or 968 box in? I'm assuming splines would be different as well as bell housing pattern but how much brain damage would it truly entail. Cheers
_________________
1980 931 "Salt" Bucket wannabe racer (not started)
1979 924 "Pepper" Restoration (almost done)
1980 924 "Donnie" (Parts car)-DEAD
1977 924 Slicktop "Pennie" Bucket turned Silver Spoon |
|
| Back to top |
|
|
Mclaren924
Joined: 13 Oct 2021
Posts: 171
Location: California
|
| Posted: Sat Nov 19, 2022 1:58 am Post subject: |
|
|
What in theory would be the best way of reinforcing the transmission? I don't plan on doing launches for a while as learned from when I blew up multiples diffs and transmissions in my subaru due to the way I had it configured it was launching far too aggressively. The 931 I can imagine will only be less forgiving so roll races will be my game for a while, still immensely hard on the trans but hopefully wont be nearly as bad as say two stepping it with my trans brake and launching it hehe. I would like to keep the snailshell in for as long as possible without killing it . we'll see how realistic this is . Cheers
_________________
1980 931 "Salt" Bucket wannabe racer (not started)
1979 924 "Pepper" Restoration (almost done)
1980 924 "Donnie" (Parts car)-DEAD
1977 924 Slicktop "Pennie" Bucket turned Silver Spoon |
|
| Back to top |
|
|
Cedric
Joined: 27 Aug 2004
Posts: 2614
Location: Sweden
|
| Posted: Sat Nov 19, 2022 2:41 am Post subject: |
|
|
Dont make it to complicated, Until you have at least400hp dont bother, just keep fresh quality oil in it and dont slam the gears, and only shift into 1st while stationary.
Btw, found this ol pic of joakims previous setup, think he ran like 380 hp or something back then.
_________________
1980 924 Turbo
www.instagram.com/garagecedric/ |
|
| Back to top |
|
|
Mike9311
Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish
|
| Posted: Sat Nov 19, 2022 7:09 am Post subject: |
|
|
Agree with that Cedric. Make 400 first then start worrying
I just looked at my Joakim pics. Didn't realize he did three variants, not two
Welded manifold to 4 bolt (Cedrics pic), then a single scroll EFR adapted to stock manifold with short bolted on adapter, then the dual scroll monster efr with headers (445hp)
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
|
| Back to top |
|
|
Mike9311
Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish
|
| Posted: Sat Nov 19, 2022 7:14 am Post subject: |
|
|
Is this Raceboy? That is a hard launch
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
|
| Back to top |
|
|
Cedric
Joined: 27 Aug 2004
Posts: 2614
Location: Sweden
|
| Posted: Sat Nov 19, 2022 8:23 am Post subject: |
|
|
I dont think the middle one is Joakims, i arranged the shipping on that Twin Scroll EFR in the lower pic, a really nice piece
_________________
1980 924 Turbo
www.instagram.com/garagecedric/ |
|
| Back to top |
|
|
Mclaren924
Joined: 13 Oct 2021
Posts: 171
Location: California
|
| Posted: Sat Nov 19, 2022 12:27 pm Post subject: |
|
|
| Mike9311 wrote: | Agree with that Cedric. Make 400 first then start worrying
I just looked at my Joakim pics. Didn't realize he did three variants, not two
Welded manifold to 4 bolt (Cedrics pic), then a single scroll EFR adapted to stock manifold with short bolted on adapter, then the dual scroll monster efr with headers (445hp)
|
Wow that things pretty large I see everyone has stayed stock location, has anyone routed it towards the front? Thinking of doing a headlight ram intake into a top mounted turbo (engine on the top side of engine compartment). Obviously would add a little more lag but ease of access and removing size constraints would make turbo choice easier. Cheers and thanks guys for answering my dumb questions!
_________________
1980 931 "Salt" Bucket wannabe racer (not started)
1979 924 "Pepper" Restoration (almost done)
1980 924 "Donnie" (Parts car)-DEAD
1977 924 Slicktop "Pennie" Bucket turned Silver Spoon |
|
| Back to top |
|
|
safe
Joined: 18 Mar 2017
Posts: 591
Location: Sweden
|
| Posted: Sat Nov 19, 2022 7:22 pm Post subject: |
|
|
I put my turbo sort of in front of the engine, but pretty low to route the exhaust under the manifold towards the stock location.
The common alternative is to do like Porsche on the 951, a crossover under the engine and the turbo up high on the drivers side.
_________________
/Magnus, Stockholm Sweden
=======================
Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe |
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
924 FAQ (Technical)
