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Hi guys I am looking for a turbo for my ze (prolly going with t3/t4) but I want to know what all the numbers means...I mean what is A/R ratio...what is a good...what is the trim size and what is O-trim...I would like somebody who know a lot about turbos to write all his knowledge and we could put this in the FAQ's cuz this is basic infos when looking for a turbo..

Go to your local bookstore and get "Maximum Boost" by Corky Bell.

I was planning to do that but for everybody else too that wants to know the answer could someone answer the question...I'm sure lots of people are asking themselves this questions..and like i said i could be put in the faq after

breaking it down gets very in depth. it's just easier for people to buy the book. this way they KNOW they're getting good info. plus the book is just AWESOME.

T3 is good for 330bhp - why would you want a bigger t3/t4 hybred ?

Two T1.5 from something like a Focus diesel might be interesting though.

Originally posted by HFStuart:
T3 is good for 330bhp.

this is a very general statement. it greatly depends on the a/r ratio, compressor wheel trim, and what stage turbine wheel. inlet/outlets also matter. all this affects the turbo's effeciency in a certain range. one t3 might be good for 330whp, while another one is out of it's effeciency range, creates more heat at upper rpms and has a lower hp.

please don't generalize like this, as people are trying to learn and so they don't run out and get some crappy spec t3 and wonder why it falls on it's face a 5k rpm.

i chose the t3t4 beacuse I've been reading for quite a while on probetalk and 80% of the people seems running t3t4's and they look to have the better performance...never saw a t3 on a klde or klze ...don't get me wrong tho it might be good..that's why i want to find out about this a/r ans trim thingy

i just bought a minute ago the book so i guess I'll have the answer to all my questions soon enough..thanx anyways

OK what I should have said is that with correct selection a T3 can make 330bhp very easily.

The point is that by selecting a turbo that is better matched to the output you want to end up with (and lets face it, what you can put down through the wheels of a FWD car) you'll get better driveability and more boost at low revs.

I still think that a twin setup would work better, possibly with one small and one larger turbo. Has anyone tried this ?

Stuart

Try to fit a TT under our hood. One intercooled turbo is beyond hard enough. And one turbo always has the ability to be more efficient than two anyways. Go to any RX-7 forum and you can see that. T78 and T04 RX-7s are beasts.

lets say that a T3/T4 will make 330 H.P. on a 1.8L 4 cylinder.

If you put that turbo onto a 5.0L ford V8, it will restrict exhaust flow and wont be able to pump enough air to make any power.

This is why you have to size the turbo to your engine size and what RPM's you want to make max power.

I'm not sure what you mean by one turbo being more efficient. A single turbo might be able to produce more power but it will be at the expense of power at low revs. That sort of 'wall of torque' power delivery is not a lot of use on a FWD car unless you run a tight diff and only drive in straight lines. Anyone whose driven a 450bhp Sierra (don't know the US/ Canadian equivalent) will tell you it's not much better with RWD either.

re A T3/T4 on a 5.0 V8, you're absolutely right it would restrict airflow for big bhp. But if it can flow enough air to make 330 bhp on a 1.8 it will still make 330 bhp on the 5.0. It'll just be at about 2000rpm This sort of setup is used on some cars to make a small engine feel like a much bigger engine in low tune, it doesn't boost high rpm bhp much just gives you much more pull low down.

T3/T4 hybrids are good turbos, if sized correctly to your application and engine specs. There are a TON of variables that come into play when sizing up a turbo. First you have to set a realistic WHP goal. Then things like your usable power band width, max rpm, how responsive you need it ect... ULTRA fast spool up isn't always a good thing or vise versa. Drag cars can actually bennifit from a little more lag so they can keep the tires hooked up. If you can't track that power then your wasting your time and your gas! AutoX'rs and road racers need more response so they can controll the cars body roll, etc... while cornering. So with this in mind here are some minor guide lines:

-larger A/R exhaust housings alow for more flow and more top end power. It usually makes a turbo feel laggier, but can work two ways if you know how to size the compressor wheel and housing A/R's. Larger housings are best for drag racing and those who are looking to spray Nitrous w/ the turbo for extra power and/ or spool up.

-small A/R exhaust housings make the turbo spool quicker, however if you go to small it will choke off a LOT of power in the mid to upper power bands. Small A/R housings are good for street cars who wanna run a big turbo with minimum lag. You can't run as much boost pressure with a small A/R exhaust housing cuz it'll choke of the exhast flow past the turbine and kill power out put.

Compressor housings are kinda similar. But then it becomes a pain staking science when combining the two of them becuase then they have variouse effects on each other. Some times a small compressor housing on a large compressor wheel with a REALY large exhaust housing isn't really a bad thing.....especially when using a LOT of Nitrous on the top end! The large exhaust housing gives you the flow you need to accomodate the MAD power levels when the Nitrous is flowing, however the smaller compressor housing helps it spool a little faster when off the bottle. There are SOOOOOOOOOOO many trade offs and different ways of doing the same thing it's not even funny!!!!!!! Just get maximum boost for your own sake! Trial and error is a not great, but expensive, lesson also.

well if you have a 2.5 a good turbo for it is either a t3/t4e with the turbine a .83 amd the t4e compressor houseing and wheel a .60. our engines need 40 lbs/hr t t3 super 60 bareley puts out over 20. i know alot of people are running t3's. but my bet with them is that they spool up really fast and flatten out really fast too. a t4e compressor goes up to around 45 lbs/hr so its a good one for us. and the turbine side we dont want it to spool too fast or we wont have traction at all. so and .83 would put it about right for us.

If you want killer power w/ fairly moderate lag, go w/ a GT 35-40R. MONSTER power capabilities with decent spool up and response on a 2.5L engine!!! I can't remember exactly, but I believe they will flow for 700+HP w/ a large exhaust side. Since it uses dual ball bearings in the center section it would be killer!!!