what's limiting my power?

[Lith]

The specs of my current turbo is. Compressor 48.2mm/67.9mm 50 trim and turbine 56mm/49 mm 7 7 trim. AR. 70. I have no idea if this is a factory td05 or something modified as there is conflicting info on the Internet.

That is the size of a 16G6 compressor wheel and TD05H turbine wheel - the internet and it's people get awfully confused about this kind of thing, and it doesn't help that there are various different size "16Gs". The one you have is the most aggressive of the range of "TD05-16G" rotating assemblies, but you have the smallest turbine and compressor housings as well - which is probably going some way to holding things back.

After the EVO 3 Mitsubishi use the exact same wheels you have but made them reverse flow, and started messing with the housings they put on them - putting larger divided housings on the turbine side and larger compressor housings, even the ultra impressive EVO 9 turbos run the same spec wheels (but reversed) as you but run a 10.5cm^2 twin scroll turbine housing versus your 7cm one, and a TD06-spec compressor housing. For what it's worth a trick some of the more cunning DSM/EVO guys in the older days used to adapt TD06 comp housings over the 16G6 to unleash some flow and it certainly works.

An example of how well this setup works is a mate capitalised on the fact that the manufacture of a JB Mitsi-based turbo is so cheap and effective by buying a Kinugawa (they take the Mitsi designs and run with them by making them for lots of different applications and combos) TD05H-16G6 with the TD06-spec comp housing and a T25 flanged 8cm^2 turbine housing for his Silvia and we've pushed it to >290kw @ hubs on E85 before running out of fuel system, power still picking up at that stage with more boost.
These guys: http://shopping.kinugawaturbo.com/kinugawaturbocharger3antisurgecovertd05h-16gt25flange8cm.aspx

Is your setup internally or externally gated?

[whynot]

Interesting stuff Lith. This is the kind of thing that just doesn't make its way to the top of the list when doing Google research.

I suspected that there would be a degree of interchangeable parts between the various turbos but it's not well documented and was hard to research.

One question still stands and that is which side of the turbo is most likely causing the restriction? Compressor or turbine? I see so many upgraded turbos and the focus seems to only be on the compressor side and almost nothing for the turbine. That's why the forced performance unit you pointed out looks like such a good option to me. They have paid attention to both sides of the turbo.

I think I will get the car back together and run it as is while I track down a suitable turbo and any associated parts required.

[Lith]

If you did look at going with the FP 68HTA turbo and are not shy of at least a slight change and have the room, I'd look at going the 3" intake (84mm FAP) compressor housing personally - I am a little dubious of the little EVO one.

Also, it is a bigger trim wheel - despite being a pretty fancy design there is no magic and a bigger trim wheel with a bigger turbine side is going to sacrifice you some response if you go there.

[Dell'Orto]

Probably a bit of hassle to swap turbo flanges now, but ATA|'s setup made the power you're after with relative ease

viewtopic.php?f=29&t=81064

Funny thing about that is that a 16G6 compressor can technically flow the same or more than a GT2860R if it's not held back by anything!

Wonder if that's purely to do with the blacktop head. Fair flow difference if thats the case!

[1I1]

Worth trying without the cat in the exhaust?

[whynot]

I really do hope that it's not the head. But I'm pretty quick at pulling the motor apart so if it does end up being the case it's not a difficult fix. By by the time I work through everything this thing will be a weapon with 4 wheels.

If that cat is the bottle neck then there is something wrong, I know they pose a restriction but this is a high flow sports unit that looks like a stainless loaf of bread mounted in the exhaust. It's huge, even more so for a 1.6L motor. But I do have a decat pipe ready to go.

I will have a new turbo ordered on Monday, forced performance fp68hta. Not sure on how long it will take to show up but it should be more than up to the task when it gets here. Will definitely get up some pics of what it looks like compared to the old one and the mandatory dyno sheets as well.

[Grrrrrrr!]

Would be interesting to check the preturbine and post turbine exhaust pressures on the current turbo and the new turbo.. got a couple of old boost guages?

[whynot]

If I get around to it I can easily check pre turbine pressures. I have gauges and steel piping as well as a 1/4" threaded fitting for egt. I don't know how motivated I will be to repeat that under the car though. Probably wouldn't read on a standard gauge anyway given its 3 inch mandrel bent.

[Crucible]

Depends what your after.

I ran a bigger turbo than yours on a stock motor and made the same power. Exh was .7 twin entry. Driveability with a big turbo on a 1600 base sucks, you wont like it. The power you are achieving seems to be quite common on a stock motor. Guys on here have gone further but I think the head will be a good place to start.

[Lith]

If I get around to it I can easily check pre turbine pressures. I have gauges and steel piping as well as a 1/4" threaded fitting for egt. I don't know how motivated I will be to repeat that under the car though. Probably wouldn't read on a standard gauge anyway given its 3 inch mandrel bent.

The new turbo probably won't offer an enormous drop in turbine inlet pressure, but probably enough to help improve the whole pound for pound increase. The compressor is one which is probably more suited to smaller engines that need higher pressure ratios to do their best, I'd not be afraid to at least in the middling rpm nudge the boost a bit higher up if you are confident your engine is up to it. If you aren't making more power in this area when raising boost then there is another issue.

[touge_ae101]

Mark is it worth measuring and plotting your relative pressures on each side of the turbo? Your essentially sizing a pump so knowing how much back pressure your exhaust system has at the floe you want it to make power at could be useful.

[Lith]

Any more news on this?

[whynot]

Yes. I have had the motor down at the workshop and it turns out the block was warped which was the cause of my blown head gaskets. While the motor was in pieces it looks like my valves had touched the Pistons at some point. Probably because of valve float as it was still running fine.

Anyway while it was in pieces I decided now was the time to upgrade a few things.....
CP rods and pistons. Balancing. Lightened flywheel. Better flowing head. That forced performance turbo you pointed out earlier. You know, just a few small bits.

It should be all back together and running in about 2 weeks and I will get some comparison pics of the old bits vs the new

[Lith]

Ahh bugger - though that could totally explain some things. If that's the case, it's probably going to be a fair bit happier beast - especially if the valves weren't actuating properly. Look forward to seeing how the new incarnation comes out

[thegreatestben]

Geeze that's a bit of a shit sandwich for a prognosis but great that you're upbeat about it and cracking on!

[whynot]

Sometimes it happens, at least I finally found what the problem was. I'm looking forward to the improved engine that's for sure.... not so much the bill, but I did budget for it.

[Dell'Orto]

Will be a weapon once its up and running again!

[Shrike]

Are you running e85 at the moment? 30kw isnt much to find e85 and some more timing plus lower temps may push you up

[whynot]

I'm not running e85. It's not readily available at the pump here (that I'm aware of anyway) and I would like to keep it simple along the lines of fill up at the gas station and have have ### power come out. I did consider water meth injection or even nitrous but that means more things to refill to continue having right foot fun. And given that a 4agte is plenty capable of making the numbers on 98 octane I would like to do it that way for now.