T4 turbo

[Turbo V6 Camaro]

Originally posted by malice10985:
So...

What exactly happens if you change A/R's on the cold side?

I have a T04 with a .81 turbine ratio, and a .60 compressor.

that something i'd like to know to...... eveything i can find only explanis the exuast side.... i know the basic i would just like a good read on what exalcy is happing

['94firebirdv6]

how much are you paying for the custom headers?

[oil pan 4]

The A/R on the compressor side should be decided in conjunction with the compressor trim most of the time.
Pick your compressor a/r depending on how much volume you want to flow (the trim and compressor size kind of decide that for you so the A/R is kind of a given for most people) and you pick your trim to flow the air efficiently at a certain pressure.
On a turbo we focus on the trim on the compressor and the A/R of the exhaust in most cases.
The exhaust a/r will decide how easy and fast we let the exhaust out and the trim on the compressor will let the air in and set's up where our turbo will flow good at what pressure ratio.
The A/R's are matched to the trim some what on the compressor.
If you had a small A/R compressor on a big engine it just would not be able to feed it enough air, it would make a lot of heat from trying to force the air through a small housing.
If you go real big the stall line (I think you call it) will be at a higher pressure ratio I think the surge line will go more to the right of the map working and start working at a higher flow (because the big a/r the air won't know where to go).
The A/R on the compressor gives the air a direction to go (or blow).
If you have a huge a/r it will just kind of sit there longer than it needs to. A big a/r will do it's best when there is a ton of air flowing through it.
On the compressor it takes fast moving air that the compressor flings off it's ends and slows it down into pressure and when you pressurize gas it heats up.
The opposite happens on the turbine.
You depressurize the exhaust and it cools some.
It is easer to pick an a/r for the turbine because you are going to have an open trim most all ways to cut down on exhaust restriction.
Most of the turbine trims I see are .70's and up to the .90's
My K03's are around a .94-.95 trim on the turbine trim. 70ish A/R
The compressor trims I have seen are as low as .40 to 70's. I don't think I have ever seen one in the .80's, that would move a hole lot of low pressure air.
On the Gas turbines I work on the first stage has divergent cross over ducts and the second stage compressor has the housing, a big housing and a small trim like a .50 but it makes 50psi of air after that 2nd stage. It has an a/r of at least 1 but it only has to work in one rpm range and it's job is to flow a ton of 50psi air. Thousands of CFM with compressor of around 9.5'' spinning 42,100rpms.

[Teufel Hunden]

Originally posted by GN-T66:
thats gigantic. you'll see full boost maybe at the top of fourth gear if you're lucky [img]tongue.gif[/img]

Even then it would just spike at full boost..i doubt there would be any length of time spent at a set pressure. :D

Don't feel bad about it though 97 30th... the exhaust housing is so easy to change, it'll take all of 10 minutes.

[97 30th RS]

Originally posted by '94firebirdv6:
how much are you paying for the custom headers?

Phoenix 64 gave me his source, I think maybe 500 bux, dunno for sure.

GNT-66, what kind of compressor wheel do you think an a/r like this would have?? I am guessing at least a 60 trim wheel, but it is probably a lot bigger.

[GN-T66]

Originally posted by 97 30th RS:
GNT-66, what kind of compressor wheel do you think an a/r like this would have?? I am guessing at least a 60 trim wheel, but it is probably a lot bigger.

60 is probably close, but I dont think it's too much bigger.

[AZ3.8Camaro]

Originally posted by viper04af:
</font><blockquote>quote:</font><hr />Originally posted by malice10985:
So...

What exactly happens if you change A/R's on the cold side?

I have a T04 with a .81 turbine ratio, and a .60 compressor.

that something i'd like to know to...... eveything i can find only explanis the exuast side.... i know the basic i would just like a good read on what exalcy is happing </font>[/QUOTE]Short answer:
It changes the compressor map, which you can read to tell if it changes for the better or worse.

[Jtownrook99firebird]

hmm... I was gonna go that way w/a t4 but... I decided 2 sell the bird all together and buy a ls1 transam instead

[97 30th RS]

I don't understand why people diss the 3.8 liter. Because it doesn't sound as good as a healthy V8? I swear if all motors sounded the same there would be more guys exploring the potential of this motor. Now with a V8 you have to pay bull**** insurance because people cannot contol doing stupid **** with them, and that affects EVERY person in this country. Of course every person here would love to have an LS1 or some kind of built big block, but in the end I would rather save myself the trouble and turbo this motor and just get 400 hp and call it a day

[oil pan 4]

I would still keep my V6.
My white Z28 gets the big motor.

[97 30th RS]

and third gens are easier to swap motors out of anyway.

[phoenix64]

9730th, have you talked to chuck yet? When you get ready to do it, look me up, I highly recomend you take a ride in my car and see what hptuners is all about. Before you invest in and FMU.

[97 30th RS]

well what time is good to meet man? I am only about 15 mins from St. Paul. I have not called Chuck yet ONLY because I want to lay down some cash to get the headers started. I know it may not be necessary but I at lest want to throw down a $100 bux or something to show I am serious.

[phoenix64]

I'm in duluth at the moment, but I'll be down down one of these up coming weekends.