Some specific T3/T4 hybrid questions

[Angus242164]

I'm getting ready to assemble a T3/T4 for my B230ET, and I have a few specific questions.

Planned setup: B230ET, 531 head, advanced K cam, ported 90+ manifold, ATP 3" V band housing, 3" turbo back exhaust, no cat, Ebay IC and custom piping, foam pod filter, chipped Motronic, Supra W55 manual trans, 4.10 rear end.

1: First of all, the T4 compressor is a T04E .60A/R housing with a 57 trim wheel (59/76mm), parts are brand new and matched.
For the T3 turbine, I have the choice of either a .48 or .63, I have both available.

I am leaning towards the .48, as I want to minimise lag. Recommendations?

2: I will be using the T04E compressor backing plate, can anybody tell me if I need a dynamic or carbon seal to use this backing plate? If it helps, there is a serrated spring steel washer fitted into the back of the backing plate.

3: Balancing: The T4 compressor wheel has been balanced, it has a section around the rim which has been milled out by machine, and also has a number of smaller marks where metal has been removed by hand with a mini die grinder or similar.

I know it's been asked before, but is there any need to balance the shaft/turbine and the compressor wheel together as an assembly? I'd like to avoid it if possible.

[BB-Q]

If it's all genuine Garrett parts then they are balanced individually, so there's no need to have the assembly balanced as a whole, although it never hurts.
The 0.48 turbine housing in the normal T3 is reckoned to flow enough gas for 320hp, the 0.63 considerably more. You need to decide whether you'll put up with a bit of lag for superior top end that you'll probably rarely use (think how often you are actually at WOT at the point where your car makes maximum power, say 5200rpm) or how much nicer it would be to drive a car that has more instant boost response.
Did you get Cosworths over there? Or that Dodge turbo that used the Cossie housing? Because the 0.48 cossie housing will flow enough for 400hp+ and yet still spool very quickly.


HTH :)

[BB-Q]

By the way, if you want ultimate power from a T04E then you need the 50trim wheel, as it outflows the rest.

[Angus242164]

To be honest even when I'm really giving the car a hard time I usually don't shift above 5000rpm, so I'm not interested in making more power above 5000, I'm after as much mid and low range power as possible.

How much of a lag increase do you think the .63 would give over the .48 in this setup, approximately?

I'm not interested in paying for a Cosworth housing as I've already invested a lot in the ATP 3" V band housing, so I will just port out the wastegate hole as big as I can, and that will be acceptable to me.

[Canuckvolvo]

Beware of the surge monster! Or never getting into the efficient range of that big turbo for that matter....

http://www.not2fast.com/turbo/glossary/turbo_calc.shtml?FeetASL=0&Tamb=20&Bore=96&Stroke=80&nCyl=4&RPM=3500&VE=95&Boost=15&Ec=73&Eic=80&PdropIC=0.5&TambIC=20&wiPercentMethanol=50&wiRate=100&wiTemp=21&SFC=.55&AFR=11.5&maxInjectorDutyCycle=85

[tryingbe]

http://www.thelostartof.net/tryingbe/forsale/cosworth1.jpg
http://www.thelostartof.net/tryingbe/forsale/cosworth2.jpg
http://www.thelostartof.net/tryingbe/forsale/cosworth3.jpg

[Angus242164]

I've been playing around with that turbo calculator Canuckvolvo, it's a neat tool. I've tried with the parameters you've entered, and also tried altering some things. I'm not fully understanding of what the surge limit is, I've read a few explanations and they say different things, but obviously it's to be avoided.

I don't know enough about some of the variables to enter into the calculator, particularly things like volumetric efficiency, so I've been varying them to see what would happen, and not surprisingly I can make the 57 trim T04E look quite suitable, or not suitable at all, depending what I vary...

I also don't understand what varies in the map when a T3 .48 is bolted to the back of the T04E 57 trim, if anything.

I really don't have sufficient understanding of it, but it looks like a T3 60 trim (is that the same as found in a 60/63 T3?) might be more suitable for my car, given that it doesn't go above 5000rpm much.

What is the outlet size of those Cosworth housings? 3"? How much do they sell for?

[benflynn]

i ra a big t3/t4 w/a 48, spooled very well, put a stg3 wheel in there, and if it ever comes around a 50trim dose trump 57

[tryingbe]

What is the outlet size of those Cosworth housings? 3"? How much do they sell for?


I believe is 2.5 inch. I'll have to check for sure. PM me, if you want pricing since you're in Australia.

[Canuckvolvo]

Angus, yes a smaller turbo would be more suitable for your engine and driving style. As for engine variables, yes, there are a ton and they all affect performance quite significantly. You can guesstimate values for VE and BSFC (the two biggest factors) to get in the ballpark with that calculator. I usually consider two points anyway- torque peak rpm and peak power rpm. VE around torque peak will be quite high, say 95%, and power peak will be more like 78% or something. Those could be quite different than real life, but they will get you some numbers that will make some sense for the purpose of turbo sizing. Use BSFC of 0.55, conservative, but realistic.
You'll see why alot of guys use the T3 60 trims or the smaller T04Es.

[benflynn]

a 40trim t3/t4 will outperfom 60trim 60/63 in flow and response, ask pete

nick will be able to tell us about a similar sized t04b

the correct turbo is just a little more than you need, but most have visions of hot chicks at their local dyno and go for broke

[Angus242164]

Thanks for the extra assistance guys, I've tried your ballpark numbers Canuck, and have been using these variables as a comparison between maps:

3000rpm, 95% VE
3500rpm, 95% VE
5400rpm, 80% VE
5800rpm, 78%VE

This is based on the turbo's spooling around the 3000rpm mark, stock B230ET making it's peak HP at 5800rpm, and the B230FT's peak torque being at approx 3500rpm (couldn't find a peak torque figure for an ET). I've gone over them using 10psi and 15psi.

Comparing the T04E 57, T04E 40, and T3 60, the T3 60 looks great, with it already being in the peak efficiency range when it spools, and efficiency drops off slightly after 5000rpm, which won't be an issue for me.

The T04E 40 looks very similar, definitely much more unused "room" in the map for increased psi in future, but isn't quite at it's peak when it spools, and is still right in it's peak above 5000rpm.

The T04E 57 looks good once it's right up on the RPM, but is well away from it's peak when it spools, only around 65-70% efficiency, and is rather close to the surge line, which I don't really understand, but I'm sure it's worth staying away from. Basically it looks reasonable at 10psi, not so good at 15psi, and simply a bit too big for this engine.

Wow, the 40 trim T3 (which I assume is the closest map to my stock 42/48 T3?) looks totally useless, even at 10psi.

I bought the 57 trim because it was cheap, brand new Garrett parts in a set, and although I always knew it was a bit too big, I didn't think it'd be an issue. It's a really nice bit of gear but I can always sell it and get some money back, or maybe use it on a future project.

I have two T3 60 trims (to the best of my knowledge) in the shed, one is a Ford housing the same as a lot of you guys in the US/Canada use, the other is a Nissan housing which came from an RB30ET, but I was told by the seller it was a hybrid made using some VG30ET parts, so I might measure those up and look into using one of them.

[benflynn]

no 57 trim, 50trim, better ALL around than 57, a big wheel in a ceramic bb nissan turbo would be pimp. send me one

[Canuckvolvo]

Your stock T3 is probably a 50 trim, so it's actually not bad, especially down around stock boost levels, 8-10psi.

The way to think about surge is- the turbo is spinning and creating boost, shoving air into the intake. A large turbo will be trying to move ALOT of air (volume), compared to a small turbo at the same boost pressure. A 2.3 liter engine only has so much capacity (volume). If the turbo is flowing more air than the engine can take, it essentially starts to choke the turbo (trying to blow hard through a small straw). Thats the surge area you want to avoid.