Clean shaved/tucked M20 turbo - TUNED 378hp/282kw

[potatomash]

So you are saying that getting more power and lot more reliable engine is stupid? In Finland almost every turbo bmw runs e85 because it's superior fuel compared to regular pump gas. Especially in turbo engines.

Haha no I'm not saying its stupid. E85 is awesome. I'm just saying the car already has enough power for me, E85 would give me more which I don't need.

There's only select spots you can get E85 in NZ so it would just make it difficult/unpractical if anything

I am inclined to say you're are choking the turbo a bit. Add a larger turbine housing and you should be relived of the creep. You have to remember the turbine is letting gasses pass just as much as the WG is, and your exhaust manifold pressures are probably through the roof.

Simple test. Put a pressure/boost gauge in your manifold somewhere before the turbo...

So your saying a pressure gauge on the actual exhaust manifold? I didn't even know that was such a thing

[ForcedFirebird]

So your saying a pressure gauge on the actual exhaust manifold? I didn't even know that was such a thing

Do a search on exhaust pressure ratios with turbo. Corky Bell touched on the subject in his book.

[potatomash]

Do a search on exhaust pressure ratios with turbo. Corky Bell touched on the subject in his book.

Oh yeah had a bit of a read up, quite interesting and makes a lot of sense. It would be interesting to see if new wastegate position/a second wastegate would alleviate it enough to get by.

If I ran an open exhaust off the turbo, or super short, technically it should reduce backpressure? Wonder if this be worth trying to see if it makes any difference

[econti]

Oh yeah had a bit of a read up, quite interesting and makes a lot of sense. It would be interesting to see if new wastegate position/a second wastegate would alleviate it enough to get by.

If I ran an open exhaust off the turbo, or super short, technically it should reduce backpressure? Wonder if this be worth trying to see if it makes any difference

I don't think it would make much of a difference unless you've got a hot like 1" downpipe

[ForcedFirebird]

The pressure you need to reduce is between the turbo and head, not after the turbine unfortunately. You should be able to just bolt on a larger housing, just match the trim. Garret offers several, listed right on the product page for the gt35.

Your turbo ratio would be more suited to a high HP small displacement engine (ie, high intake flow, small exhaust in NA form, such as a Honda etc.).

[potatomash]

It was originally off a friends Evo so guess that kinda makes sense.

I'm thinking of doing something like this with my wastegate to see if I can get away with the current housing. It just spools up so well so I want to keep it nice and responsive if I can..

[eduTechnic]

This is exactly what a lot of guys do. Go for it!

Check this guy's 6.0 turbo video

[potatomash]

Manifold and turbo off to get modified..



While it's not going I'm working on the next piece of the puzzle..

[Northern]

The WG off the housing seems to be the easiest way to achieve good WG placement in an E30. Most E30 turbo manifolds seem to have the same problem with WG tube placement just because there's so little space, especially if you leave extra clearance to the sides to take into account all the different engine mounting setups people use

If I ran an open exhaust off the turbo, or super short, technically it should reduce backpressure? Wonder if this be worth trying to see if it makes any difference

WG dump to atmosphere would be the best way to lower pressure after the WG, which should more gas to flow through the WG instead of the turbine. Downsides are potential legal issues and noise.

Lowering the pressure after the turbine should make more power, but I don't know how much it would do for your creep issues.

[varg]

Pressure after the wastegate is rarely a problem on any setup, you'd have to be plumbing it into an already restrictive exhaust system or using a pipe that is smaller than the wastegate outlet. I'm not a fan of screamer pipes, they're obnoxious, and from a tuner's point of view they make a car harder to tune since they're so damn loud - good luck hearing any detonation over the wailing rasp. I'd say the problem is that there's too much demand for flow on the wastegate with the small turbine housing.

[akorcovelos]

Dyno is done, car is beast. No 1st or 2nd, and lucky if I get half of 3rd..

What is your limiter set at? Seems like peak power is kinda low in the RPMS.

I am inclined to say you're are choking the turbo a bit. Add a larger turbine housing and you should be relived of the creep. You have to remember the turbine is letting gasses pass just as much as the WG is, and your exhaust manifold pressures are probably through the roof.

Simple test. Put a pressure/boost gauge in your manifold somewhere before the turbo. Compare that to your intake manifold pressure. If you are approaching a 2:1 ratio, then your turbine and/or gate is too small - it will always creep since the exhaust gasses being created by large compressor/turbine ratio have no where to go. People think in terms of flow on boosted exhaust, but in reality, it pressure ratios that are the important part. 1:1 would be a perfect world, but closer to 1.5:1 is more typical on a well designed system.

I wonder why the tuner scene doesn't use EGT gauges like the Hi/Po diesel folks do? Monitoring boost vs EGTs is the main thing I look at in my truck when pulling...

[potatomash]

... I'm not a fan of screamer pipes, they're obnoxious, and from a tuner's point of view they make a car harder to tune since they're so damn loud - good luck hearing any detonation over the wailing rasp...

Ahah theres lovers and haters right, I'm all about the obnoxiousity. My tuner deals with dirty RB's on a daily so he's used to them :p

What is your limiter set at? Seems like peak power is kinda low in the RPMS.

Limi is 6500, there's not really much point going higher

My cage now has 4 feet..

[wazzu70]

I wonder why the tuner scene doesn't use EGT gauges like the Hi/Po diesel folks do? Monitoring boost vs EGTs is the main thing I look at in my truck when pulling...

Diesel is more sensitive to EGT. Looking at the gauge you will see the temps are much lower than a petrol engine. Diesel components are made to resist high temperatures so risk of damage due to EGT is higher. That said, its not a bad thing to check. I have an EGT gauge in my BMW, and I calibrate diesel engines so I know both well :)

[downforce22]

I have the same manifold on a 3.1L stroker m20 and i have some boost creep also. good to hear I'm not the only one. I thought increasing boost pressure might help it. I have a 6 psi spring and creep up to 9 psi. turbo is a precision 5862, wastegate tial mvr 44 mm

[wazzu70]

The problem is you are running a larger turbo at minimum capacity. One 44mm gate is not big enough to bypass all the exhaust volume you need to barely work the turbo. You can add another wastegate, increase wastegate size, or run a boost pressure thats in the operating range of the turbo!