Choosing Turbo Specs

[adam 32]

ive had a big bastard on my car for too long. its a TA34 (T04E) Garrett with 1.06 exhaust housing which sees boost come at around 4500-5000rpm which makes good top end but very little streetable power

i want to rebuild the turbo using the same compressor setup but smaller exhaust size which will bring boost down to around 3000rpm. im thinking a .63-.68 housing. but also want to make decent power. currently the car makes 270rwhp @ 14psi (RB20) and i want to have at least 250 by the time the operation is complete. other factors are dont really want to have to contract a welder or change oil/water lines/intake pipes etc. the turbo currently sits on an HKS manifold with an external w/gate

what do you reckon i should do? just change the exhaust housing, is this a good/bad idea? or is there an easier way around?

thanks

adam

[meggala]

not sure but the exhaust housing is the palce to start talk to some turbo shops they will be able to fill you in

yeah adam it is laggy to laggy for me

51-52 mm exhaust whell might be the right size check though

meggala

[Joe]

I have a t04e also

How big is the Compressor Wheel & housing?..

Mine is a .50 AR compressor not sure about housing, its quite large thou

My Exhaust housing is .63

From my understanding, it will start spooling around 3000-3500rpm around that mark & will hit full boost at 4000rpm i reckon.

I havent fitted it in yet as i have had endless bills 2 pay for.

Call up a few turbo place around your area & see what they say.

make sure you have all the spec of the turbo thou as it will be easier on both parts.

1.06 exhaust housing....whaooo it would of came out of a rotor or a v8.

[Steve]

For your output requirements, I dont think you will have a problem. With the AR ratio you have at the moment, most probably you are just starting to make good power when you are running out of revs? I would have thought that with the smaller turbine housing, you most likely would be getting more useable power lower down - and unlikely a T04E will be running out of puff even if you get it starting to make boost as low as 3000. You will still have plenty up top, perhaps get more than 270rwhp.

If it gives you any idea, the HKS3037S comes in a 0.61 turbine AR which I believe is a similar size to the T04E? or maybe a bit bigger.

Have you had any head work, vernier cam gears, or cams done - these will all get you on boost alot quicker too.

Steve

[sidewaymambo]

Know someone has the following spec..

RB20 ---> 50/63

RB25 --->60/80

spooled at 3000, hit hard on 4300, saw in my own eyes..trust me..

[adam 32]

so even the .63 doesnt see full boost til 4300!! i was hoping for earlier. having said that my car hits hard at about 5500 in 2nd gear, not good! its cool for overtaking but otherwise just a pain in the ass

can i go smaller than a .63 or will i start to sacrifice power and practicality

[JH32]

Why don't you sell that turbo adam and buy one of those 2845 or whatever they are? Ask MrMayhem he loves them and he'll tell you exactly what they are

[macka]

Adam u get full spool at 4600 if i remember...

It hits hard after 5 because its reaching your powerbad...

Your not interested in this at the moment.

You just want it to hit 1 Bar @ about 3500rpm

[adam 32]

sidewaymambo says full boost by 4300 with a 0.63 exhaust. this is still a little laggy...

[sidewaymambo]

adam go for .50 or 53.....exhaust housing..but if the cost is way too much, you might consider sell it and save a bit go for 2835..if you don't want change internal and stay 14 psi..

[Clint32]

Mine is a TO4 with 0.6 comp and exh housings, it has a large exhaust wheel (58mm from memory) and makes full boost at 4500, if you had a smaller wheel you could get this down to 4g i think, mine made 235rwkw or 315HP at the wheels, on 16psi. While it is laggy compared to some i dont find it too bad to drive and will still keep up with most up to 3k in traffice but once you hit 4k you just have to hang on.

If you can find i cheap second hand exhast housing it would be worth doing but will still cost a few hundy to do, not easy to find either.

with a turbo like this type of setup you will always have a fair bit of lag, unfortunately you cant have everything its eather cheap power and lag, or expensive power with a little lag.

[Joe]

as long as its starts 2 spool at 3000rpm theres nothing wrong with that, if it starts 2 spool at 4000rpm, i would go insane personally.

You bought a cheap turbo, dont expect 2 much bang out of it, if u want 220-230rwkw go for a gt2530. but u would have to go back to the factory manifold or get a adapter made up as you have the hks t04e manifld made for the rb20/25det.

With people with the hks manifold, did it fit stright in as in you didnt have to remove anything 2 fit it in

as in aircon!

anything above .64 on an exhaust housing is too big for a 2L.

[adam 32]

the car came like this. the turbo rubs on air con lines but theyve been covered in heat shield protectant stuff.

i see 1psi at 3000rpm but it spools so ****ing slowly that its not full boost til 4500-5000rpm. bottom line is its too laggy and im sick of it. plus im making decent numbers on a dyno but converting that into shit street power because of the nature of the power band. my power curve on the dyno is vertical

is 0.63 the most popular exh housing to bring it down to? the thing im most ocncerned with is not having to change inlet/outlet piping, dump pipe, oil/water lines and all that other shit which makes changing a turbo very epxensive. im hoping to get away with the whole operation for under $1000 (trading in my existing exh setup)

[Joe]

.62-.64 is the most popular yes, i think if you go any lower there would be 2 much restriction.

Yeah power figure would be great on the car but power curve is another story, the conversion should fix it.

[Steve]

Adam, might be worth having a look at this:

http://board.performanceforums.com/...readid=67142909

1.5bar at < 4000rpm, 0.48AR ratio turbine with a T04B compressor

Just some more possibilities

[adam 32]

the main reason for rebuilding tho is because ive got a good manifold/wastegate setup already. its just the exhaust which is too big, everything else is great!

[mint]

I'm very interested in this also.

as I am helping a friend with his Turbo upgrade.

what are the prefered spec for a T04 onto a RB20DET?

from compressor housing/wheels/exh housing.

[Steve]

Preferred for what? what one person preferres is different to the next. Are you after mid range, top end - drag, circuit, street?

[BOOSTD]

I have a T04vtrim with .8 (VG30) exhuast housing and 42mm wheel. I has wicked surge issues. Makes full boost by 3000rpm. Have got around the surge with dual stage boost 10psi up to 4000rpm then 13.5.

[Sydneykid]

Hi adam 32, have you ever had the tuning done to improve the boost build and response or is it always done just to increase the max horsepower?

If I was tuning it, I'd try stuff like;

* advance the exhaust camshaft timing a bit

* retard the inlet camshaft timing a very tiny bit

* advance the igntion timing a lot

* turn the boost down so that it doesn't detonate with this amount of ignition advance

* marginally richen the mixture up to the point of max torque

* increase the spark plug gap

* tune the wastegate to make sure it is not opening slightly at less than the desired boost

There are some things you could do as well, simple stuff like wrap the exhaust everywhere from the engine to the cat in exhaust heat shield wrap, make sure the intercooler piping is not more than 2.5" (63 mm) in diameter, wrap the intercooler pipework from the turbo to the intercooler and then to the throttle body.

All this will help the boost build quicker and improve the response. You may end up with slightly less max power, but I will bet the average power in the rpm range you use increases substantially.

Hope that helps