the thing is they are not that cheap, I just bought a used vf48 for my wrx after months of shopping around and for $200 more dollars you can get a kinugawa 16g-18g-or 20g. a vf39-vf43-vf48, are still very fast spooling turbos on the 2.0 boxer ej20. on a 2.7l m20 they will run out of steam extremely fast, probably produce extremely high intake temps. your best bet would be a cheap cxracing gt28 turbo, fast spool,dirt cheap, no custom fab needed and with methanol can make good number with really good drive-ability. a gt30 would be perfect for the 2.7l, I feel the 20g is too small for anything above a 2.5L
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The concept that a few of the guys such as Mattias and Gunni went over and over is that these two valve motors are sensitive to back pressure. Very sensitive. I refused to believe this was the case and used a GT2871 and paid for it by having to re-do the whole turbo system again.
The GT2871 has a turbine exducer of about 50mm, GT3076 is about 55mm. Mattias was uncompromising that even 55mm was too small. It was 60mm minimum, or go home.
I probably could have combated the detonation with the GT using h20/meth, but it still didn't change the fact that the motor was choking on its own fart. Reversion was rife.
On 9psi using the S256, the motor was now rev-happy and sounded good. It was also much easier to modulate the power delivery whereas the GT was a light switch.
You can say you "only want" X amount of HP, but the reality is that we always want more. When I built the car I was happy to see maybe 230-250 RWHP, pfft! Yeah! I pushed the boost a bit more and got to around 300RWHP and ran into all sorts of detonation.Comment
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Thats the cheapish turbo Im running currently, Havent had detonating issues but my tunes are not aggressive at all. I believe its gt28 sized.
Im going to upgrade to non chinese turbo soon, but Ive run it for almost 3000 miles with no issues.
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If you go cheap turbo I'd stick to cxracing becuase they are all computer balanced before shipment. We have/had 3 turbo E30's here in Reno running cxracing turbos and all are doing just fine.
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You'd laugh if you ever visited the CXracing warehouse like I did a couple times.
A bunch of turbos, intercoolers, pipes and stuff piled high in a corner lmao.
I'm not sure what for though, maybe warrantied items, but the thought was just funny when you mentioned computer balanced.
I've been thinking long and hard for an 18g billet wheel Kinugawa. Wheel sizes are between a 76r and 71r Garrett.
1991 325iS turbo
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im so lost in this... no idea who to listen to lol.Comment
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Confusing eh! I spent so much time agonising over the turbo choice, but I ended up just going with iXer's (Mattias) suggestion.
Your HP goals of 350-400 dictate you will needs a fairly capable turbo. I really, REALLY, recommend getting a turbo with a big exducer and twin scroll. A HX35 with a 12-14cm2 exhaust housing, an S256 with a 0.84 housing. Both these units are twin scroll and are not much money. The S256 317444 is a much newer design than the HX35 with its 'extended tips' and make some glorious whistle.
In the Garrett range, I have not looked over these for a while. Garrett seems to make a lot of turbo's that are large (ish) in the compressor and smaller in the turbine. If I could have mated the comp wheel from a 3076 to the turbine of a 4082, I would have. But they are different shaft sizes.
In the diesel world, where HX35 and S256 originate, the turbines are pretty large compared to the comp. The S256 has a 65mm turbine exducer and a 56mm compressor inducer. I was concerned about being laggy as I even bought the biggest AR turbine housing, but have data logs to prove 11psi at 2800rpm. It boost even earlier on E85.
Big turbines allow you to run more ignition timing due to there being less back pressure, less gas reversion, less end gas contamination, less heat. As Mattias said, yes, the smaller units like a 3076 may make some decent power on the M20, but how long will the stock M20 tolerate the above conditions? It can make a few highway pulls, but how about a track day?
Talking to another guy who ran the 3076 on his M20, he said the thing is too small and impossible to modulate and control. I found the situation even worse than his when I was using the GT2871 -0032. Conversely, I found the S256 I could modulate the amount of tire roastage with the right foot. It was all or nothing with the GT.
Another point, and I know the Gt2871 was small, but the way the engine revved with the S256 was amazing. It just wanted to pound out to the rev limiter and sounded happy and glorious doing it as opposed to the GT. All I had to do was uncork its butt!Comment
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seeing that you actually did this helps alot. Since college has started otherthings have come up. i dont have a full time job anymore so i will be just focusing on actually building a 2.7i with all the same internals as in the original post. my dad has a 69 datsun roadster that will take up the rest of the time, so i wont have time for messing with a turbo set up anyways for a while. in the mean time ill keep doing research about turbo set ups and what i want. and i guess i will be going with a hx35 or s256 for a turbo. seams like the best choice according to a lot of people.Comment
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I have a friend that's going to sell his hx35 out of his cummins. I can ask him what he wants for it and get you pictures if your interestedComment
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ya that would be great. thanksComment
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Never seen a cheap s256. Which truck did it come off of?Your signature picture has been removed since it contained the Photobucket "upgrade your account" image.
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A Volvo that parked in my street once......
</JK>
It is stock fitment to a 6 liter Volvo Penta Diesel, which I think is a marine engine. I paid much more for it new here in Aus ($1600) than you can buy them in the USA (~$1000). This made it around the same price as the GT2871 I removed and it's a lot more turbo!
Spend a little, get a little.Comment
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I was looking at some s300 turbos on ebay. They are about 700 new. Sizing seems right for a 3.0l build.Your signature picture has been removed since it contained the Photobucket "upgrade your account" image.
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