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Mclaren924
Joined: 13 Oct 2021
Posts: 171
Location: California
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 Posted: Sun Nov 13, 2022 1:45 am Post subject: Best way to fit a modern turbo |
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I'm finally getting around to my 80 931 and have decided against restoring it and will be taking it full race car. I plan to run the original motor for a long while and I was wondering what you guys thought the best way of mounting a modern turbo are? I'm currently teaching myself Tig welding so I'm into the idea of just cutting off the 3 bolt flange and welding on a 4 bolt flange... Open to ideas! cheers,
Malcolm
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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 |
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11723
Location: PacNW
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| Posted: Sun Nov 13, 2022 2:18 am Post subject: |
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Not to naysay but a 931 is a poor race car. I'm on an enduro team that runs one, and the owner put massive effort into staying with the 2.0 lump (including custom manifold with modern turbo), but it just wasn't viable. The car now has an Audi 5 cyl. turbo, which, thanks to the Audi derived bellhousing, is a friendly conversion.
You can check out the build here: https://www.924board.org/viewtopic.php?t=44218&sid=608736b9a093802c48a87a292943edeb
Good luck!
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Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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Cedric
Joined: 27 Aug 2004
Posts: 2610
Location: Sweden
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| Posted: Sun Nov 13, 2022 3:20 am Post subject: |
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It can absolutely be a good race car if you know what your doing. Ive seen both, both cut and welded flange (Joakim ran at 400hp for a long time with such a manifold) and just an adapter. Try to see if an adapter would fit, that would create less risk of cracking, and good manifolds are always worth some money. I even think i have a mitsubish turbo adapter in my stash that i got when i bought a bunch of parts 
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1980 924 Turbo
www.instagram.com/garagecedric/ |
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Carrera RSR
Joined: 08 Jan 2010
Posts: 2309
Location: Somerset, UK
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| Posted: Sun Nov 13, 2022 4:09 am Post subject: |
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Best way to fit a modern turbo is start with a 944 turbo shell + motor 
_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252 |
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Mike9311
Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish
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| Posted: Mon Nov 14, 2022 12:36 am Post subject: |
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Scroll down on this link, first page. Plenty of size choices. Tyler's was at the smaller end of the efr line
https://www.924board.org/viewtopic.php?t=43003
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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 |
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Mclaren924
Joined: 13 Oct 2021
Posts: 171
Location: California
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| Posted: Mon Nov 14, 2022 4:35 am Post subject: |
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| Cedric wrote: | | It can absolutely be a good race car if you know what your doing. Ive seen both, both cut and welded flange (Joakim ran at 400hp for a long time with such a manifold) and just an adapter. Try to see if an adapter would fit, that would create less risk of cracking, and good manifolds are always worth some money. I even think i have a mitsubish turbo adapter in my stash that i got when i bought a bunch of parts |
I have tossed and turned the idea of using a different car all together or swapping motors right away and have decided to keep its original motor until I run out of spare pistons and blocks and then will probably be going for a K24 swap. In the meantime I don't really want to bother messing with the k26 turbo it has, I know some good gains have been seen swapping housings and stuff but I'd rather go with a ball bearing or twin scroll, not to mention why wouldn't I want to go bigger as well . My concerns with welding onto the flange is obviously it cracking as those parts are already prone to stress cracks. Really this 931 build will help me learn all the different fronts of efi and turbo setup building so really there is no worse case scenario. I don't use shops unless it's coming down to needing a 5-axis cnc machine or something along those lines so I plan to try and keep it all in house.
_________________
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 |
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Cedric
Joined: 27 Aug 2004
Posts: 2610
Location: Sweden
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| Posted: Mon Nov 14, 2022 6:26 pm Post subject: |
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| Mclaren924 wrote: | | Cedric wrote: | | It can absolutely be a good race car if you know what your doing. Ive seen both, both cut and welded flange (Joakim ran at 400hp for a long time with such a manifold) and just an adapter. Try to see if an adapter would fit, that would create less risk of cracking, and good manifolds are always worth some money. I even think i have a mitsubish turbo adapter in my stash that i got when i bought a bunch of parts |
I have tossed and turned the idea of using a different car all together or swapping motors right away and have decided to keep its original motor until I run out of spare pistons and blocks and then will probably be going for a K24 swap. In the meantime I don't really want to bother messing with the k26 turbo it has, I know some good gains have been seen swapping housings and stuff but I'd rather go with a ball bearing or twin scroll, not to mention why wouldn't I want to go bigger as well . My concerns with welding onto the flange is obviously it cracking as those parts are already prone to stress cracks. Really this 931 build will help me learn all the different fronts of efi and turbo setup building so really there is no worse case scenario. I don't use shops unless it's coming down to needing a 5-axis cnc machine or something along those lines so I plan to try and keep it all in house. |
If you can i would really recommend a twin scroll manifold like liilldudes in the thread above. Especially if you will run std pistons, twin scroll creates less risk of detonation. If you will run std pistons its very very important that you keep it out of detonation at high power levels.
You could also do the more elaborate version like joakims, check the video, but i think it wont be worth the extra effort. Though he ran close to 400hp for many years with a cut and welded std manifold and garret turbo
https://www.youtube.com/watch?v=Maae0lF1mXs&t=18s
The other version with much less effort is the screw on adapter like this one:
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1980 924 Turbo
www.instagram.com/garagecedric/ |
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safe
Joined: 18 Mar 2017
Posts: 588
Location: Sweden
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| Posted: Tue Nov 15, 2022 1:52 am Post subject: |
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What is "full race car"?
For a fun track day car, sure plenty of capability.
Being competitive in racing, that depends alot on the regulations where you are planing to compete and how much money you are willing to sink into the project.
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/Magnus, Stockholm Sweden
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Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe |
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Mclaren924
Joined: 13 Oct 2021
Posts: 171
Location: California
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| Posted: Tue Nov 15, 2022 2:21 am Post subject: |
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| Cedric wrote: | | Mclaren924 wrote: | | Cedric wrote: | | It can absolutely be a good race car if you know what your doing. Ive seen both, both cut and welded flange (Joakim ran at 400hp for a long time with such a manifold) and just an adapter. Try to see if an adapter would fit, that would create less risk of cracking, and good manifolds are always worth some money. I even think i have a mitsubish turbo adapter in my stash that i got when i bought a bunch of parts |
I have tossed and turned the idea of using a different car all together or swapping motors right away and have decided to keep its original motor until I run out of spare pistons and blocks and then will probably be going for a K24 swap. In the meantime I don't really want to bother messing with the k26 turbo it has, I know some good gains have been seen swapping housings and stuff but I'd rather go with a ball bearing or twin scroll, not to mention why wouldn't I want to go bigger as well . My concerns with welding onto the flange is obviously it cracking as those parts are already prone to stress cracks. Really this 931 build will help me learn all the different fronts of efi and turbo setup building so really there is no worse case scenario. I don't use shops unless it's coming down to needing a 5-axis cnc machine or something along those lines so I plan to try and keep it all in house. |
If you can i would really recommend a twin scroll manifold like liilldudes in the thread above. Especially if you will run std pistons, twin scroll creates less risk of detonation. If you will run std pistons its very very important that you keep it out of detonation at high power levels.
You could also do the more elaborate version like joakims, check the video, but i think it wont be worth the extra effort. Though he ran close to 400hp for many years with a cut and welded std manifold and garret turbo
https://www.youtube.com/watch?v=Maae0lF1mXs&t=18s
The other version with much less effort is the screw on adapter like this one:
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I am walking the line between just running two stock bottom ends up till they blow and then k swapping it. I don't see the investment being worth it for custom pistons and rods, this would cost at least 1500$ itself. I have two complete motors for parts so I'm probably just going to run stock motor just upgrade to headstuds and cometic hg and send her to the moon. Would you be open to selling that Mitsubishi adapter or at least taking some pics or a scan of the flange and sending it my way? I'm still learning and don't want to make a crappy part or setup because I know they are already brittle. Mittle motor has a gts aluminum replica for sale, https://www.mittelmotor.de/racing/de/webshop/14206/6548/924-944/4-10-rennsport/2-4-01501s-neu-detail
My thoughts are to go with a garret turbo and just weld on a flange until I am proficient enough to weld up an entire manifold. I would base it somewhat similarly to the gts intake. The question is also what turbo to use? I'm shooting for the moon as I've said so size would have to be borderline outlandish but I don't like waiting for boost either... Cedric you mentioned pre detonation and I plan on running e85 to help combat this as well as a methanol setup to keep intake air temps down .The methanol I have a good idea what to do as Morghen is already making an awesome kit for his SC builds. The e85 is my biggest question, I guess it wouldn't be so hard when thought about. Go rob a flex fuel setup off of a newer random car and make sure I have an ecm that can read it? Sure Im making it sound easier than it is. I could spend all day picking your brain lmao
_________________
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 |
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Mclaren924
Joined: 13 Oct 2021
Posts: 171
Location: California
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| Posted: Tue Nov 15, 2022 2:39 am Post subject: |
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| safe wrote: | What is "full race car"?
For a fun track day car, sure plenty of capability.
Being competitive in racing, that depends alot on the regulations where you are planing to compete and how much money you are willing to sink into the project. |
Had a whole message typed out and I miskicked and lost it fml lol. 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.
_________________
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 |
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Cedric
Joined: 27 Aug 2004
Posts: 2610
Location: Sweden
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| Posted: Tue Nov 15, 2022 5:19 am Post subject: |
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I can scan my adapter if you want to, but i guess its very specific for one kind of turbine housing. Wouldnt be comfortable selling it though, since it looks a bit badly welded.
For a start i wouldnt bother with a different intake manifold, start out with what you have. I dont see why you would need to blow engines either, take it small steps at a time and start out safely at maybe 300hp and see how you like it, and get everything to work, it will already feel reallly quick.
e85 is the cheapest racefule you can find, if its available go for it, absolutely. just dont be too greedy with the ignition timing so you dont lift the head or something. then you could probably skip the methanol if you mount a good FMIC.
Measure the block head very carefully, if its not absolutely close to flat you would probably be better of with a std gasket, dont ask me how i know that  . the best would be to machine head and block flat, the blocks ive had at home as sunken down a bit, like all old cast iron blocks do after 40 years of thermal loads.
Im not sure what power goals and budget you have, regarding turbo choice. "safe" has a pretty wild one in his turbo converted n/a, designed to put several bars of boost in there, not sure its needed here. Set some goals first, and then chose the stuff you need. Especially since it isnt a race car with any set rule set you have to follow.
Not sure how well a K would fit in there, its a very tall engine, and lots of custom work needed. Its not as quick and easy as a 25k usd youtube swap with all ready made ktuned parts Would probably still cost lots and lots of money, good quality swaps tend to do that in the real world. But they are nice engines.
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1980 924 Turbo
www.instagram.com/garagecedric/ |
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safe
Joined: 18 Mar 2017
Posts: 588
Location: Sweden
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| Posted: Tue Nov 15, 2022 7:14 am Post subject: |
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| 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.
_________________
/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 |
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Mclaren924
Joined: 13 Oct 2021
Posts: 171
Location: California
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| Posted: Tue Nov 15, 2022 11:56 am Post subject: |
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| Cedric wrote: | I can scan my adapter if you want to, but i guess its very specific for one kind of turbine housing. Wouldnt be comfortable selling it though, since it looks a bit badly welded.
For a start i wouldnt bother with a different intake manifold, start out with what you have. I dont see why you would need to blow engines either, take it small steps at a time and start out safely at maybe 300hp and see how you like it, and get everything to work, it will already feel reallly quick.
e85 is the cheapest racefule you can find, if its available go for it, absolutely. just dont be too greedy with the ignition timing so you dont lift the head or something. then you could probably skip the methanol if you mount a good FMIC.
Measure the block head very carefully, if its not absolutely close to flat you would probably be better of with a std gasket, dont ask me how i know that . the best would be to machine head and block flat, the blocks ive had at home as sunken down a bit, like all old cast iron blocks do after 40 years of thermal loads.
Im not sure what power goals and budget you have, regarding turbo choice. "safe" has a pretty wild one in his turbo converted n/a, designed to put several bars of boost in there, not sure its needed here. Set some goals first, and then chose the stuff you need. Especially since it isnt a race car with any set rule set you have to follow.
Not sure how well a K would fit in there, its a very tall engine, and lots of custom work needed. Its not as quick and easy as a 25k usd youtube swap with all ready made ktuned parts Would probably still cost lots and lots of money, good quality swaps tend to do that in the real world. But they are nice engines. |
It's okay about the adapter and I appreciate the advice, intercooler will realistically be one of the first mods for the car as that will help keep it alive as well as allow me turn it up more. I know the K swap wouldn't be any walk in the park but I like tough projects. Don't laugh but I took the fuel tank out of my donor today and god that sucker is perfectly snug up there! Never had a tank just sit and have to be pryed out after all straps and connections removed. Back to the topic though I plan on just trying to get her alive on efi and stock turbo first and then I can worry about adding all the other fun stuff. I do want to run a fuel rail setup with bigger injectors so any ideas on that would be awesome too, I remember reading about a 1.9 ford escort rail maybe? After shes alive and well I'll worry more about strapping her up for liftoff, unless you guys think this may be a waste of time to setup on a stock turbo first? Dunno don't want to end up and unfinished efi thread lol. Cheers for the advice guys really appreciate it.
_________________
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 |
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Mclaren924
Joined: 13 Oct 2021
Posts: 171
Location: California
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| Posted: Tue Nov 15, 2022 12:01 pm Post subject: |
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| 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.
_________________
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 |
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Mclaren924
Joined: 13 Oct 2021
Posts: 171
Location: California
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| Posted: Tue Nov 15, 2022 4:47 pm Post subject: |
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| Rasta Monsta wrote: | Not to naysay but a 931 is a poor race car. I'm on an enduro team that runs one, and the owner put massive effort into staying with the 2.0 lump (including custom manifold with modern turbo), but it just wasn't viable. The car now has an Audi 5 cyl. turbo, which, thanks to the Audi derived bellhousing, is a friendly conversion.
You can check out the build here: https://www.924board.org/viewtopic.php?t=44218&sid=608736b9a093802c48a87a292943edeb
Good luck! |
I actually got to see that car in person when I went up and bought some 5-lug and a 5 speed and turbo head off of Britain. Such a cool car man, equally as cool is his graveyard of snailshells cases, think he had like 14 lmao. Yeah the original motor is really just something I have already and for what Im capable of now it will definitely be a good learning experience. Call me crazy but I really want a subaru awd system behind a Honda K24 motor in one of these chasis and make a car similar to ken blocks hoonigan. I have crazy ideas that only my pockets can prevent from me attempting... I appreciate all the advice as I need it lol. Am debating making a thread or two for my cars as I've got a shit ton 924 related stuff going on right now but I'm also worried about posting too much lol.
_________________
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 |
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924 FAQ (Technical)
