Turbo Sizing -- big and small

[TasCressida]

ok guys here is a probably a stupid question.
googled it but cant find a simple answer.... probably isnt one.

ok u have two turbos-

one has a small front housing ....and a rather large exhaust housing.

and the other has a big front housing and smaller exhaust housing.

fit to 1JZGTE also


whats the benefit of both variations and the draw backs.
what applications would either one suit.
both externally gated.
i know turbo wheel sizing prob has something to do with it but im just going off
housing sizes.

any opinions would be good....cheers

[jimmmayyy]

whats the a/r's and what are the turbos?

larger exhaust housing is really meant for engines that produce alot of high velocity gas, like rotaries. on a 1J it may spool fairly slowly depending how big it is. conversly, if its too small it may spike easily. same with the compressor, a smaller one will spool quicker, but it may not pump enough air up top. it will also make the charge air hotter than a larger one.

[mic*]

Very generally;

Bigger exhaust turbine means more lag and higher boost threshold for the same motor. More outright power may be possible as larger exhaust turbines cause less manifold backpressure (evil).

Compressor (intake) sizing is mostly up to how much boost do you wana make? Pick a compressor that is efficient at the flow vs boost combination at which you wana make power. Compressor size has little effect on lag & boost threshold compared to ex size.

[af300e]

Large compressor housing would be more for higher flow I suppose.

[mic*]

The turbine must be sized so that it spins the compressor fast enough to make boost (boost threshold) within the desired rev range yet not become overly restrictive at max revs & boost. Comprimise is obvious and depends on your purpose. A/R (area/radius) ratio, turbine design and clearance to housing all manipulate the tradeoff - read ART.

The compressor is a case of the one thats most efficient. Its necessary to calculate mass flow rates for the engine at various revs and boost, then look at where they lie on the efficiency maps of prospective compressors...

Or you just ask someone who's done a few on that motor what good for what

[Ribfeast]

GT3076R with 0.82 housing on your 1JZ should get you round 350-400hp and be nice and responsive on the street.

[TasCressida]

ok ill find the specs on mine. its a TD07SH 25G built by MTQ.
but they made it bigger again. Dr.Drift had it built for me to suit large horsepower.
it has an enormous front housing and a medium size exhaust housing.
im looking for over 450 hp at the treads so i hope it will be fine.
im promised it should be perfect for more than that.

will ring them and ask for the specs again.
its to suit drag style racing wheich im building the car for.

cheers for all the info guys!

[jimmmayyy]

Shit yeah a TD07 would go very nicely on a 1J, maybe a little laggy but since your building it for drags itd be perfect.

[trd3sg]

Is this auto or manual?

[TasCressida]

its auto mate? why u ask?

[trd3sg]

different spool up chracteristics - i will repost later as i have to duck out now

[jimmmayyy]

an auto will keep building boost through a gear change, could even spike a little between the gear change. manual will drop most of the boost through a gear change.

its not a huge problem, so long as theres no huge uncontrolled spike of boost between gears.

[trd3sg]

i was referring more towards the loading up of the motor to reach the required exh gas velocity

auto - depending on whether running a large convertor - may be harder\easier to bring the motor onto boost with larger exhaust housing, and also depending on the setup

Is it for bracket racing or a specific class? Is it purely for a good ET and bragging rights?- reason im asking is you wouldnt want to burn your convertor out while you sit there at the tree trying to bring it on boost cos you have such a larger exducer \ exh wheel. Then again, some giggle gas would solve that but you'd have to check if its permissable in your category.

[6BOOST]

Thats like saying I have 2 pieces of string that I want to tie a knot in, one is long, one is short, which one would be better........

Housings sizes to some extent are pointless, without all wheel sizes and info. A small wheel in a bigger housing will prob make the same or similar power at same spool rpm's as a bigger wheel in a smaller housing. When you have some specific info, you might get some specific answers, until which point you'll get a whole lot of round about answers and "opinions".

6BOOST