Hey guys I'm wrapping up an OBD1 M52 swap in my 87 325e. I'm ready to add a turbo setup but I'm having issues deciding on a good turbo setup for this platform. I'm looking for good power but nothing too extreme as the car is a daily driver clutch has already been upgraded and is rated for right around 550 safety. I just have no idea where to start as the only other turbo setup I've done was on my MKV GTI which I went from a K03 to a GT28. Looking to knock this out in the next 2 weeks so I can start tearing apart my audi so any suggestion are welcome! Thanks for the help guys!:)
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You've got 24 valves, let that baby breath! get atleast a gt3067r, mitsu 20g or 12cm hx35 (if you get a split pulse mani).
Though my take on your situation (and I'm working on a 2.7i turbo) is going 24v for a turbo is kind of a waste unless you want more than 350 hp. M20's make 300 whp where 24v makes 400, but 24v adds considerable weight unless you go with an aluminum block m52, which don't take boost as well as the iron block 6's. Also, all m52's are vanos which will have to be tuned in accordance to your spool up and boost levels.
m20b27 Turbo. Hx35. Twinscroll Mani. MS1. 42lbers
http://www.r3vlimited.com/board/showthread.php?t=338818 -
Go big or go home, even if this will be a daily drive ..
My vote is GT35r or similar ..Comment
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GT30 has a 55mm turbine, 20G is around 55mm too. HX35 has 60mm, now we are getting somewhere if you are after breathing. S256 has 65mm and is proven to make 550 crank HP on M50B28 * Gunni recently built two m50's with this spec.Comment
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Is the engine stock? stock compression? And how much power you looking to make?Originally posted by Jacksontheogre View PostNeed a Turbo manifold? We have them in stock- Click here---> http://rapidspoolindustries.com/
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Dyno vid http://www.youtube.com/watch?v=C7aM7..._order&list=ULComment
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You need to go look up compressor maps for various turbos to figure out what you want by plotting the mass flow rates and pressure ratios based on the engine crank hp you want to make. Sure you can have people tell you what turbo to run, and it will probably make good power, but if you want your car to drive the way YOU want it to you should understand everything about how turbos are sized and designed.Originally posted by Jacksontheogre View Post
For instance, a GT3582R from garrett is a great turbo for making lots of power, but with the 1.02 A/R turbine housing it is going to spool up so late that you probably won't have much useable power.
You need to do some research and figure out what you really want. Don't rely on other people to tell you how to do things. With that being said, a great place to start looking for compressor maps or sizing help is turbo manufacturers websites. Garrett has some useful pages for sizing help, as does Borg Warner. There are also plenty of books on amazon that explain how turbo systems work and how to size a turbo properly. Just my $.02Comment
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motor is stock although I do have APR studs and a thicker head gasket laying around and could use if need be, the compression is stock as well. I don't have a number in mind at the moment but I don't want to create a situation where I have to end up building the entire motor to run this turbo. I'm sure in the long run I will want more power and a built motor but for now I just need something basic.Originally posted by Good & Tight View PostComment
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Yeah, don't rely on people who have been there and done that.
One of the guys used a 3582 and the 4500rpm spool drove him nuts. On the other hand, an S256 has 11 psi at 2800rpm on a stock M20B27.
look for about 55mm inducer size and 60mm exducer for your goal.Comment
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Stock compression motor will handle 8psi max with a very good tune.Originally posted by Jacksontheogre View Post
A Garrett 57 trim .63 back housing is a properly sized turbo.
If you decided you want to run more than 8psi then ARP's and dropping the compression is a must.Need a Turbo manifold? We have them in stock- Click here---> http://rapidspoolindustries.com/
____________________________
E-mail Panayiotisx2@gmail.com
Dyno vid http://www.youtube.com/watch?v=C7aM7..._order&list=ULComment
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What would a reliable boost level be with stock compression, ARP's and o-ringed block with stock HG? Assume car is tracked and has a good tune.Originally posted by Good & Tight View PostComment
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Sounds like I should go ahead and just put the APR studs in since I have them, and I guess if I'm going to do that i should go ahead and do the head gasket. How thick should I go?Originally posted by Good & Tight View PostComment
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I'm not saying experience isn't valuable, I'm just saying don't get so-and-so turbo because joe blow on the internet told you to without doing any research. Person A might love turbo lag and the "throw you back in the seat" feeling it gives you when the power comes on, but Person B might like less peak power with more useable power in the mid range. But without doing research and understanding why a turbo makes an engine perform the way it does, you may end up not liking how the car behaves after installing the turbo.Originally posted by Nutzy View Post
It's just a suggestion. Do what you want, its your car and your moneyComment
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A fair point, but there are very valid reasons not to use small turbines on these motors, especially the M20. The M50 is probably not as sensitive to back pressure.
Running stock high compression is also another reason you REALLY don't want back pressure, reversion, and heat.
When big free breathing turbines like the 65mm exducer on the S256 317444 spool in the mid 2000 rpm, why settle for turbo's that might work? Turbo's such as the ex diesel HX series and the Schwitzer's have large turbines compared to their compressors. Garrett's etc are usually the other way around unless they are hybrids.
This is my 11psi 300whp dyno run on the B27. The cut is at 6200 so you can see there is a nice broad area under the curve.
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So its looking like a GT30 is a happy medium between not enough and turbo lag, should I lower the compression with this size turbo if so, how large of a head gasket should I pick up. I think the on I have is .80 or something of that nature,Comment
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