Don't castrate me - turboing a stock 2.5L

[blau]

I recently picked up an 87 924S for a ridiculous price ($700) in obscenely good shape. However, coming from VWs, the idea of boosting a car always comes to mind. I know that people have asked about how to up the power of the stock 2.5L and the response is typically "Buy a 951", but for the price I paid and a 2.5T in a 924...well yeah. I was hoping to go half junkyard, maybe pull a T3/T4 out of a Volvo or Saab. I have a friend that fabs custom manis and tubing, so that's covered. Bigger injectors and MS would make fueling easy, I hope. Has anyone done this before? Does anyone know how much boost the stock engine can hold before blowing rods and such? Why so much apprehension? Lack of room? There's more room in a 924 bay with the 2.5L than in the bay of my VW Mk3 VR6 and people turbo VRs all the time...

Sorry for the nubile inquisition. I promise that if I get shot down hard enough on here I won't do it.

[blown 944]

No backlash from me

I would say to use the search button but I don't think it would be very helpful. It had been shot down so many times that I think people just gave up.

[blau]

Yeah, every search just pulls up some kid asking if there's a turbo kit for his 944 and subsequently getting burnt to a crisp. This would be a fully custom job...Perhaps I'll be the first? Yeah right.

Seems like a regular 924 with the Audi bubble block would be really easy to turn into a 16v VW motor to boost to the moon.

[blown 944]

You never know if you'll be the first, but who cares, if you want to do it go for it.

I didn't back down and am still having fun with my lil pos car after 3 years of abuse

[AaronM]

If you know what you're doing, you can do it. Especially if you have the time and resources to fabricate all the parts. However, you will not be looking at a high-boost engine. The pistons are not forged, nor are the rods, and you will be dealing with a high compression ratio, which will necessarily mean lower boost. You'll want to watch that. As opposed to being able to run 15+ PSI like many do with a 951 engine, you'll be looking at 5-8 PSI with the higher compression and less-durable components of the standard 944 engine (assuming no other modifications).

You'll also need to upgrade the clutch assembly (pressure plate, etc) and the transaxle (or at least the ring and pinion in the differential) because that's a weak point already with the stock 944 NA engine and if you're adding power then it's a worthwhile upgrade.

In the end, while it's possible, the car will be slower than a 944 Turbo, and will not handle as well. Plus it will be almost impossible to sell since everything will be custom, so you won't get much (if any) return on the investment.

The reason for the normal apprehension is that for the cost/effort of properly setting up a turbo on the NA 944, you approach the cost of a decent 951 ($6,500-$8,000 for a solid driver), but you don't have the advantages of the 951's upgraded transmission, suspension, and brakes, and you're still not producing as much power. You also have a car that cannot easily be worked on by another mechanic since they won't be familiar with the custom pieces and is hard to sell because of this.

It's not that it's impossible, just time consuming and it requires a lot of attention to detail to get the same level of reliability as a factory 951. Remember that there are people out there on all-original 951 engines who have reliably put 200,000 miles on their cars. If you want to do it, great, go for it. But remember that it's a labor of love and still won't give you the same kind of power or handling that you can get out of a factory Turbo.

[Schumi]

Look into a microsquirt- they are available now I believe. There is someone here that is working on adapting a microsquirt to a stock harness.

[rmcdonnell]

Sid (Blown 944) is spot on: I think you should search in this forum for more info, there is plenty to find. If you are after a sweet experience, I would find out more (from him for choice) about the supercharger route instead. More bang.
Less buck.
You make me hungry for more; but I typed NOS in the search and found few takers.
Back in my world I'm spraying water in there, just to clean it up!

cheers
Russell

[moorepower]

I seem to remember someone here or on Rennlist who has a 924S with a 951 motor and clutch with a 968 six-speed in it. If you can find a wrecked 951 and do a swap, that seems to be the easiest, cheapest, and most reliable way to go. But if you're looking for an engineering project to play around with, then go for it

Keep us updated.

[blau]

Originally Posted by AaronM

If you know what you're doing, you can do it. Especially if you have the time and resources to fabricate all the parts. However, you will not be looking at a high-boost engine. The pistons are not forged, nor are the rods, and you will be dealing with a high compression ratio, which will necessarily mean lower boost. You'll want to watch that. As opposed to being able to run 15+ PSI like many do with a 951 engine, you'll be looking at 5-8 PSI with the higher compression and less-durable components of the standard 944 engine (assuming no other modifications).

You'll also need to upgrade the clutch assembly (pressure plate, etc) and the transaxle (or at least the ring and pinion in the differential) because that's a weak point already with the stock 944 NA engine and if you're adding power then it's a worthwhile upgrade.

In the end, while it's possible, the car will be slower than a 944 Turbo, and will not handle as well. Plus it will be almost impossible to sell since everything will be custom, so you won't get much (if any) return on the investment.

The reason for the normal apprehension is that for the cost/effort of properly setting up a turbo on the NA 944, you approach the cost of a decent 951 ($6,500-$8,000 for a solid driver), but you don't have the advantages of the 951's upgraded transmission, suspension, and brakes, and you're still not producing as much power. You also have a car that cannot easily be worked on by another mechanic since they won't be familiar with the custom pieces and is hard to sell because of this.

It's not that it's impossible, just time consuming and it requires a lot of attention to detail to get the same level of reliability as a factory 951. Remember that there are people out there on all-original 951 engines who have reliably put 200,000 miles on their cars. If you want to do it, great, go for it. But remember that it's a labor of love and still won't give you the same kind of power or handling that you can get out of a factory Turbo.

Ah, the info I was looking for - thanks! My followup questions were going to be "how much power can the drivetrain/clutch handle", and it appears it has been answered (I was hoping for around 250whp in a decent JY setup). Definitely sounds like a daunting task. I wasn't sure on how much componentry the 951 and 944 shared. Finding a wrecked 951 and swapping everything in would be awesome, but out here in Utah the WC Porsches are few and far between. I think I'll likely stay N/A, maybe save my dollars for a 951, as the g/f refuses to approve of a daily driver 80s Porsche to replace the 2000 Golf 1.8t...

[AaronM]

Originally Posted by blau

Ah, the info I was looking for - thanks! My followup questions were going to be "how much power can the drivetrain/clutch handle", and it appears it has been answered (I was hoping for around 250whp in a decent JY setup).

Yeah, that's the real kicker is the drivetrain. The stock 944 clutch and transaxle is just about maxed out with stock power, in fact, it's not uncommon to hear about people blowing their R&P from aggressive 1/4 mile runs in stone-stock 944 NA's. If you were very careful, you could probably keep the stock 944 NA driveline alive even with stock 951 levels of power, but I wouldn't trust it. Porsche certainly didn't.

250 RWHP would be very ambitious to put it mildly. A stock 944 NA has around 125 RWHP. A stock 951 will put down around 195 RWHP (in non-S trim). My modded and chipped 951 with an "S" turbo puts down about 275 RWHP and 300 RWTQ at 15 PSI.

It can definitely be done, but it's not really cost-effective given the going rate for a 951. On the other hand, it's a great way to learn a lot and more power to those who have pulled it off. Blown944 is proof that it can be done. Just bear in mind that it's not a small thing. Of course, just because it's a big job doesn't mean it's a bad idea.

[speedracing944]

Expect about 170 RWHP for a N/A boosted to 5-6 psi.

Check out blown944's project "lil mule". He uses a M90 supercharger which can be had for $150-$250 and would provide instant boost.

Speedy

[todd84944]

I have parted out a couple of 951 engines. I have most everything to convert a n/a engine to turbo, including the pistons. I don't have a intercooler though.

[Dana Norris]

Its your car do what ever you want, Its not like they only made two of them.I would not like to see this forum (924,944,968) turn into the purist cra#p that I see on the 912 and 911 forum`s. If in the after life one was to meet DR. Porsche I an sure he would tell you drive the sh%t out of it thats what we built them for. ENJOY It`s just a car.

__________________________________________________ ____

1984 944 first Porsche Sold
1969 912 Hot Rod with 1974 2.4 Injected 6 Sold
1976 911S with 3.0 SC Motor Sold
1986 944 NA 145,000 miles still going strong

[onZedge]

No, I won't castrate you. I can't seem to find my hacksaw anyway. However, once you get it all sorted out and start whining about low end turbo lag, please don't ask us how to NA your turbo!! I'll probably tell you to use a 10-25HP NO2 hit with a window switch and/or boost switch anyway. There was an article in Import Tuner several months ago about doing just that. Impressive results on a drifter.

[Icey1174]

It's a little more than just a $250 M90. You have to get bigger injectors, plumbing, adjustable fuel pressure reg, pullies, a new belt, and most important, you'll need to measure the temps to properly tune it. Thorw in an intercooler for good measure and you can be around 12 PSI of boost for about $1000. Big different in power for $1000 and it looks and sounds cool too.

I'm in the middle of the conversion. I upgraded my injectors to 45 PSI. I bought new ones for $250 with shipping. Used ones on ebay are not much cheaper because you are stuck getting 6 or 8 of them rather than just 4. I found the Eaton M90 for $175. An intercooler for about $120. The adjustable fuel pressure regulator was about $100 (I think) from Lindsey Racing. I also bought a fuel pressure gauge and mounted it to my fuel rail. Tht was about $50 with shipping. A new belt is about $50. Now to measure internal temps. A good EGT is $300. So now you're at $1K with the plumbing you'll have to do too. Add a boost gauage so you know what you have.

All and all it looks like a good project. You may want to upgrade to the turbo head gasket too. Add another $80. Sid had great luck with it. Some other fab work for the intake as well. Search for his threads. He did a nice job on his 944.

[Dean924s]

I am going down that road as well. You may find this spreadsheet helpful. I was specifically interested in laminar flow in the intake when I made it but I added a bunch of other things just because I could. I should end up with about 7PSI when I am done. I can post the specifics to my project if you all are interested. I am using an M62 from a MB230 Kompressor. So far I am going to keep the clutched pulley but I will probably replace it with a smaller pulley and that will eliminate the pulley.

http://www.ehadesign.com/~dsmith/ENGINE_AIRFLOW.htm

[blown 944]

Dean glad to see someone else is doing it.

There is a very good thread here where this guy used teh same S/C you are and he did some things I wouldn't do (built a huge lower pulley)but considering the size of engine the boost most likely will be close to what you will end up with.

This is a very long and interesting read

link: http://forums.nasioc.com/forums/showthread.php?t=605625

[Dean924s]

link: http://forums.nasioc.com/forums/showthread.php?t=605625

That is a LONG LONG thread. But there is a wealth of info. I was not going to intercool at first (same as him) and only go to 5PSI but after reading his trials and tribulations it looks like an intercooler is a must if you want the motor to hold together. I was thinking of trying to go through the whole thing again and paraphrase what he did what worked and what did not. In essence try to shorten the learning curve.

What I have done.

I am mounting the SC on top of the AC delete bracket I have. I have had a custom bracket/plate made up that bolts to the 4 ac delete bracket bolts. The head unit then mounts to the steel plate by welding extended nuts I can not think of there name but they are used fro joining pieces of threaded rod together. These are welded to the plate steel. I thought that the alignment of the head unit was going to be an SOB but careful measuring and putting things in to AUTO-Cad so I can overlay/model them to get the alignment was the key. This arrangement stacks the SC over the alternator. I am going to extend a bracket down to put a idler pulley between the Head unit and the alternator. I was thinking of using the one from a Ford as it is spring loaded and will keep tension yet allow for belt slip if something goes really wrong. I will probably try this but eventually go back to a fixed Idler and tension the belt using the alternator adjustments. BTW if I have measured things correctly I will be able to use a stock 944 belt form an AC car.

I have got a RRFPR from my wife's SC mustang (vortech kit) (Runs 7-8 lbs of boost on a 3.8). The RRFPR was an extra that I got thinking hers was bad but it was really a vacuum issue. I have a secondary high volume fuel pump (again from the vortech kit) that I may need to install or I will just go get a pump from a 951.

After reading about the Subi I am convinced now that more than ever that timing and fuel control and inter-cooling is key. Even with relatively low boost #'s that I am wanting to get to.

People should understand that I am not building a 951. I can go by one of those. I am having fun.

[Porsche-O-Phile]

I'll sell my Callaway conversion kit - for the right price.

http://forums.pelicanparts.com/showthread.php?t=366088

[BauDMoN]

I have looked at the non-turbo to turbo conversions and found it is NEVER worth it.

Why?
1. Engine upgrades and mounts to handle added compression, hp, torsion, etc.
2. Drivetrain upgrades to clutch, trans-axle, gearing, etc.
3. Suspension upgrades to handle the higher speeds
4. Braking upgrades to slow you down.

Conclusion:
Buy a turbo that is pre-engineered to include all of the above, and enjoy the driving time.