T04b 50 trim, couple fins minor bends...rebuild, straighten, or ignore it?

[Rice Over Wheat]

I'm buying a turbo/manifold off someone and there are a couple fins on the compressor wheel with minor bends. The turbo pulled great on his car and still flowed 47-49 lb/min so I don't think they are bad enough to have hurt performance much. However, I am wondering if it is worth the investment to send it in to FP for a new compressor wheel and balance, or carefully use two needle nose pliers to straighten them without putting pressure on the shaft....or should I just leave it alone and bolt it on as is? This turbo will be staying on for at least 18 to 24 months and I just want to do it right. I'll try and get a pic up soon as well.

 

[ThingyNess]

I think the general consensus would be to consider the turbo as needing a rebuild, and pay accordingly. If he thinks it's worth as much as a good condition used T04b, then let him sell it to someone else. There are so many 50 trims up for sale all the time, it doesn't really make much sense to buy one with a damaged compressor wheel. The wheels are pretty brittle/fragile, and it doesn't take much to break them.

If the wheel is bent, the turbo is likely out of balance now, which puts more stress on the bearings as well. If it's been like that (bent) for a while, it will probably accelerate bearing wear, and if you're going to send it to FP, you might want to consider getting the whole thing rebuilt and the shaft checked for straightness while you're at it, seeing as something had to have damaged the rotating assembly in the first place for it to be bent.

I probably would pay no more than $200 for it, and consider it a core, if I was in your situation, and run it until it breaks and cut your losses and buy a non-damaged turbo. 50 trim T04bs are a dime a dozen these days anyway.

 

[Rice Over Wheat]

I've considered that, however remember that I'm getting the manifold with it already flanged for my 38mm tial. A partial rebuild will cost about $175 for what I need done, and even with that it is still cheaper/easier than buying a new 50 trim + manifold, or gating my stock one. Again, this turbo still flowed 47+ lb/min. As things stand now, I would be moving from a T28 to 50 trim setup for about $200 when all is said and done. This is why it is giving me pause for thought.

The alternative is buying this turbo, the best price I could find: http://www.extremepsi.com/store/customer/product.php?productid=18905&cat=961&page=1

$700 is basically my budget for a turbo as I already bought a tial 38mm and 50 trim install kit. So I would have to have my stock manifold welded for the external gate and a dump tube fabbed. This would all end up costing me about $300 more than it would if I went with the turbo/manifold deal.

 

[daren_p]

Like said above, it may flow fine now but having a couple bent fins will throw it out of balance & you have to remember these things are spinning at 100K + rpms. This will defently shorten the turbo's life. As to how long it will last thats hard to say. I too would base how much I was paying for it with the cost of having it rebuild factored in as it will more then likely need it sometime.

 

[ThingyNess]

Why not just get a used 50 trim that doesn't need a rebuild and run your gate off the O2 housing? This is a much better approach than the typical "weld a 38mm flange onto the #1 runner" set up most people who run external gates off the manifold use, and allows you to keep the manifold you already have.

Punishment racing sells a TiAl 38mm recirculated O2 housing for only $215 shipped. They don't show it on their website, but if I recall correctly, the non-recirculated version that includes a dump tube is the same price if you prefer to dump your wastegate to atmosphere. Or if you wanted to be a little cheaper, you can grab an O2 housing flange, a downpipe flange, and a couple TiAL 38mm flanges and fab your own up for in and around the $100 range.

I'd much prefer that over most of the silly stock manifold/wastegate flange welded monstrosities that are out there (or the cheapo ebay tubular manifolds, for that matter).

It also gives you the ability to upgrade your manifold later on, should circumstances dictate that, if you wanted to get an FPRace manifold, an EVOIII one, a SBR cast one, or whatever else, your wastegate setup is still usable.

At only $215 shipped, that leaves almost $500 left for you to find a used 50 trim, which should be readily available at that price without the bent fins.

 

[Rice Over Wheat]

Like said above, it may flow fine now but having a couple bent fins will throw it out of balance & you have to remember these things are spinning at 100K + rpms. This will defently shorten the turbo's life. As to how long it will last thats hard to say. I too would base how much I was paying for it with the cost of having it rebuild factored in as it will more then likely need it sometime.

Yes, that's what I'm concerned about. The owner has driven 5000 miles over 6 months on the turbo as is. I'm thinking over the long term since I would be keeping it on a daily driver for about two years. I just don't want any surprises down the road.

Why not just get a used 50 trim that doesn't need a rebuild and run your gate off the O2 housing? This is a much better approach than the typical "weld a 38mm flange onto the #1 runner" set up most people who run external gates off the manifold use, and allows you to keep the manifold you already have.

Punishment racing sells a TiAl 38mm recirculated O2 housing for only $215 shipped. They don't show it on their website, but if I recall correctly, the non-recirculated version that includes a dump tube is the same price if you prefer to dump your wastegate to atmosphere. Or if you wanted to be a little cheaper, you can grab an O2 housing flange, a downpipe flange, and a couple TiAL 38mm flanges and fab your own up for in and around the $100 range.

I'd much prefer that over most of the silly stock manifold/wastegate flange welded monstrosities that are out there (or the cheapo ebay tubular manifolds, for that matter).

It also gives you the ability to upgrade your manifold later on, should circumstances dictate that, if you wanted to get an FPRace manifold, an EVOIII one, a SBR cast one, or whatever else, your wastegate setup is still usable.

At only $215 shipped, that leaves almost $500 left for you to find a used 50 trim, which should be readily available at that price without the bent fins.

A lot of the guys around here running nice setups are dumping off the manifold instead of the O2 housing. I don't understand what the advantage/disadvantage is to either method regarding managing boost pressure? I have noticed that dumping to atmosphere off the manifold is much quieter than off an O2 housing.

Fabbing a Tial wastegate off my O2 isn't an option as I don't have those tools available for that. Buying a gated O2 housing would raise my costs $200...that would be ok if I found another 50 trim like you said, but I don't like to buy such things on the net, I like to see it in person, and I don't know of anyone else locally selling one. I would probably have to go new. In that case, gating the manifold is free. I would rather stay in budget now as I am willing to do it over a year or two down the line when I free up more money.

 

[Rice Over Wheat]

Spent the last hour reading threads about manifold vs o2 external gates and none of them really give a performance reason for choosing one over the other. The most compelling reason I read was on the FP race manifold thread which mentioned tapping the #1 runner means the other three's exhaust gases have to purge upstream through the gate.

I bought the Punishment mild steel Tial 38mm recirc O2 housing, 215 shipped. I hope this doesn't require a slimline fan now!

I am leaning towards the bullseye 50 trim, $700, from extremepsi.

 

[ThingyNess]

Running a wastegate off the manifold isn't intrinsically a bad idea, but the way most DSMers have it set up is.

You want to run your wastegate plumbing such that your gate is venting from all four cylinders equally. On a proper manifold-mounted wastegate, this would occur right at the collector.

An example of the proper way to do it is here.

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Most DSMers run the flange off the #1 runner. This is because we're a bunch of cheap-asses, and it's the only way you'll get a 38mm TiAl flange to sit properly on the stock manifold, which gives you an external gate solution for the cost of a $20 mild steel flange and some time/money to weld it on. This, unfortunately, means that you're primarily going to be venting the gases from one cylinder.

This is bad for a couple of reasons.

1) The localized reduction in back pressure with the wastegate open is going to mess with the VE of that cylinder, which in turn is going to affect your A/F ratio for that one particular cylinder. Even worse, if/when your VE changes, it's likely going to be for the better (at least locally), causing that cylinder to run leaner. Does not make for a happy engine, particularly if you like to tune even slightly aggressively on pump gas.

2) Because of the placement, when your wastegate opens, you will be asking very high velocity exhaust gases that your manifold has been designed to smoothly collect and aim down the throat of your turbine housing to take an abrupt 180 degree turn and go back UP the #1 runner and out the wastegate flange. Even worse, this happens more and more as you need to vent more of your exhaust out your wastegate. Which, in most circumstances, is precisely when you need the best flow out of your manifold, because you're making the most power, and also have the most flow through your turbine as well.

On a street car, this is particularly bad, because if you're running low to moderate boost on a large turbo that's capable of a fair bit more, you are going to be venting a very large percentage of your exhaust gases out the wastegate, which is more exhaust that has to make that 180 degree turn up the #1 runner, straight into the exhaust flow coming out of the #1 exhaust port. It may seem counter-intuitive, but on a race car running high boost and close to the turbocharger's limits, it's much less of an issue since the wastegate won't have to vent nearly the same quantity of exhaust gas.

There's a reason why OEM wastegates tend to vent from the throat of the turbine housing, and it's not by accident.

Robert from Forced Performance touched on this in his thread about the new FPRace manifold as well, in case you don't believe me. He has a lot more credibility than I do.

http://www.dsmtuners.com/forums/showpost.php?p=151116261&postcount=3

Don't get me wrong, it will certainly work. So will dumping your stock BOV to atmosphere with the factory ECU, and so will running 20" chrome spinners on your Eclipse. They're all sub-optimal solutions though, and frowned upon for a reason.

 

[2gAWDTalon]

Huh, so turbonetics must be a bunch of dumbass when they desgned this manifold?

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You points make sence and you sound like you know what you are talking about but lets not reinvent the wheel here ok...

 

[Rice Over Wheat]

Good post, Thingy. Yeah that's what I gathered from his FP manifold thread, which is why I was hesitating to do it. But like you said it's cost effective. Maybe it's less significant a factor for applications up to 450 or so? 2gAWDtalon's setup you see there pulls like a raped ape and part of the reason I decided to upgrade.

 

[ThingyNess]

Huh, so turbonetics must be a bunch of dumbass when they desgned this manifold?

No, I'm not saying that at all. I am, however, saying that performance and good design wasn't high on the list of their criteria when they designed it. Turbonetics designed their manifold the way they did simply because it made packaging things easier. If they put the flange right on the collector, no matter which way they pointed it, it'd have either a) hit the hood, or b) hit the rad and fans.

They designed their manifold that way because it does work, even if it doesn't work as well as it should, or as well as another design would. Making a mold to cast a tube in that routed the wastegate gases from the collector over to the side where the actual wastegate sits would have been prohibitively expensive and perhaps prone to cracking as well. Their design goals were low cost and ease of packaging, rather than performance.

Engineering is all about tradeoffs. Few people design things because they WANT them to be bad, but you have to choose which criteria are important to you and make your decision accordingly.

In this case, the price you pay for the ability to retain your existing downpipe and turbo completely unmodified, and an inexpensive manifold, is poor wastegating and poor manifold flow.

For some, this would be an okay tradeoff, I suppose, if you were cheap. However, when a $215 O2 housing exists to mount your wastegate in a much better location, and is cheaper than the Turbonetics manifold to boot, I can't imagine why anyone would ever want to buy one.

Then again, as I mentioned before, some people make a vented BOV on the factory ECU their first "performance" modification.

 

[Rice Over Wheat]

I ended up going with a new Bullseye T04b 50 trim from extremepsi.com, externally gated to the 38mm recirc'd Punishment O2 housing. Total cost, $916 not including the tial. $1136 with the tial.

 

[TurboAnything]

I talked about the single runner wastegate mistake early on. It's a bad idea. Hear me now and believe me later, I didn't just fall off the turnip truck guys. FP will never make a single runner wastegate manifold, I don't care how many would sell if it was that way - it is the WRONG way and we will just not do it. I wanted to make a manifold that was as perfect as possible for our FP30s, and this is it. Just so happens that it works for 16g just as well.

just thought i would put this in here

 

[GVR4592]

Huh, so turbonetics must be a bunch of dumbass when they desgned this manifold?

Yes they were stupid when they put the wastegate on the #1 runner.


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