Turbo Stockers

[Jimi B]

I am not a turbo dodge or ford expert, but I do tune a lot of turbo cars. Wideband afr gauge is the most important tool for me. I haven't used or even seen a egt gauge in a turbo car in years. Knowing the AFR, especially on a wideband, is a lot more acurate way of tuning. You will pick up dangerous AFRs before you see the dangerous EGTs. Like I said I'm not a turbo dodge or ford guy, and certianly some of these guys have it figured out, just sharing my experiences.

[art leong]

Originally Posted by Marc Kinton

We have an EGT. What numbers shall I get you from that. I will look into the SVO gasket.

My best runs were at just below 1800 degrees at the finish line, with the probe about 1 inch from the head.
I just adjusted the fuel pressure to get the egt number I wanted

[Marc Kinton]

Originally Posted by art leong

My best runs were at just below 1800 degrees at the finish line, with the probe about 1 inch from the head.
I just adjusted the fuel pressure to get the egt number I wanted

I assume that lowering the fuel pressure lowers the egt? and vice versa

[art leong]

Originally Posted by Marc Kinton

I assume that lowering the fuel pressure lowers the egt? and vice versa

Nope just the opposite. Bring the fuel down it raises EGT's. Put more fuel in it lowers them.

[Rob Lloyd]

Bringing this one back up because it's time for a new turbo.

So, what exactly does the turbo rule mean? The housing can be 2mm bigger than the max allowed turbocharger size? What size? The wheel OD? Where is that size published? No mention of the wheel size, so I assume it has to be the max allowed size - whatever that is.

All of my turbos are used and slightly worn, but I honestly don't know what the stock size is supposed to be. It would be nice to know exactly how much these turbine wheels are worn down. And, whether or not I should invest in a new one.

Art - do you have the stock specs for the Mitsubishi turbo used on the TD's?

[Jimi B]

I wouldnt be real concerned with it. You know you have a stock turbo. Just get the correct rebuild parts. As far as that dia of the inlet.. It says Turbocharger size will be verified by measuring the housing bore at the leading edge of the impeller wheel. So basically measuring the dia. of the inlet right at the front of the compressor wheel. If you are not aloud to change the wheel I dont see much need play with the inlest size.. Not 2mm anyway. Every little bit helps I suppose. But I would think that you would want the tolerance to be tight right at the wheel...

[art leong]

I always just bought new or good shape used Mitsu's. Never had them check the same things twice. Some of the way they measured was laughable.
I gave them a stock turbo to keep and I think they threw in the trash before they left the track.
With the exhaust system I had I could make 18 pounds or so (in great air)
That was enough 1800 degrees at the finish line.

[art leong]

Originally Posted by Marc Kinton

I assume that lowering the fuel pressure lowers the egt? and vice versa

Just saw this post raising fuel lowers EGT lowering it raises EGT.

[Rob Lloyd]

Originally Posted by Jimi B

I wouldnt be real concerned with it. You know you have a stock turbo. Just get the correct rebuild parts. As far as that dia of the inlet.. It says Turbocharger size will be verified by measuring the housing bore at the leading edge of the impeller wheel. So basically measuring the dia. of the inlet right at the front of the compressor wheel. If you are not aloud to change the wheel I dont see much need play with the inlest size.. Not 2mm anyway. Every little bit helps I suppose. But I would think that you would want the tolerance to be tight right at the wheel...

I'm not to worried about the compressor side. It's the turbine I'm worried about. I have a good turbine housing, but all of my turbines measure at least 0.04 smaller than the housing at the exducer. I think maybe my turbines are worn down pretty far. My guess is it should only have 0.01" clearance, but I don't know for sure what the turbine is supposed to be. I found some specs that say it should be 1.88" - mine measure more like 1.84". Ouch! But, again, the housing bore measures close to 1.88" So, I don't know if that spec is for the housing or the turbine.

You definitely do NOT want 2mm clearance around the compressor. It will cause a very slow boost rise. You want as small a clearance as you can run on the compressor side.

Related question - Art, did you have trouble seizing the wastegate arms? I seem to seize one up every single season. The 'good' turbine housing I mentioned above I shelved because it seized the WG arm. I took it apart and reamed it out, but I'm concerned it will just seize up again. I reamed it with a 5/16" drill (the arm measured 8mm, so there's alot of clearance now). Just gotta get the arm welded back up and put my 'good' turbine in there for Indy...

[art leong]

Originally Posted by Rob Lloyd

I'm not to worried about the compressor side. It's the turbine I'm worried about. I have a good turbine housing, but all of my turbines measure at least 0.04 smaller than the housing at the exducer. I think maybe my turbines are worn down pretty far. My guess is it should only have 0.01" clearance, but I don't know for sure what the turbine is supposed to be. I found some specs that say it should be 1.88" - mine measure more like 1.84". Ouch! But, again, the housing bore measures close to 1.88" So, I don't know if that spec is for the housing or the turbine.

You definitely do NOT want 2mm clearance around the compressor. It will cause a very slow boost rise. You want as small a clearance as you can run on the compressor side.

Related question - Art, did you have trouble seizing the wastegate arms? I seem to seize one up every single season. The 'good' turbine housing I mentioned above I shelved because it seized the WG arm. I took it apart and reamed it out, but I'm concerned it will just seize up again. I reamed it with a 5/16" drill (the arm measured 8mm, so there's alot of clearance now). Just gotta get the arm welded back up and put my 'good' turbine in there for Indy...

It happened to me a few times especially when the car sat for a couple of months. I would just free it up. Then put it back together.
It happened when I sold the car to Jim. Took it to Cecil County Went to the line, The car left like a garbage truck. I knew what the problem was but the look on Jims face was priceless I knew he was thinking what did I come up here for? Loosened it up, ran the expected number. And the car was on it's way to Fla.

If I were you I'd look for some heat resistant preoiled bushing And install that.
It seems to be the leaded gas that does it Jimmy Malone hasn't had it happen to him that I know of and he uses the VP unleaded.