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Super-70 or T-70? Big difference.

 

Putting a 70 MM Compressor on a T-3 manifold/houing problaby won't work well at all. 60 mm is about the safe limits for an older garrett style wheel in the T-3 series.

 

Much bigger than 60 mm and you need the T-4 housing to make it efficent.

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My 62-1 T3 sucked balls compared to the 60-1 T4. better balance front to back. You don't want a compressor that vastly outsizes the turbine wheel. Same concept as to why the TD05-20G sucks comapred to something like a TD06-18G.

 

Housing AR's ave very important, but if it has a T-3 wheel on a 70 mm compressor, it's going ot suck regardless of A/R. It's about balancing back pressure, A/R does little help with back pressure and is more for charge velosity and low RPM turbulance control.

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T4 is the way to go for these cars. t3/t4 is what guys ran on these cars when we were still scared to experiment out of the box. I have a t4 sc63 with a ptrim .58

it is one mean piece of turbo but you must have all supporting mods+tuning to really exploit a good sized snail.

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chad and lionbull, what kind of exhaust housings are your current turbos? divided? A/R? When do they spool, like what rpm?

 

And Chad, you should take a look at modern T3 turbos. Precision has turbos like 6262 and 6265 or 6765, etc. where the first two numbers are the size of the inducer on the compressor, and the second pair of numbers is the exducer on the turbine. My 6262 is a T4/T3 with an exhaust wheel that is the same size (basically) as the compressor.

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T-70 is not a modern turbo, the design is decades old in fact.

 

I'm sure there is a reason Precision doesn't make a 7065, that is the reason I'm talking about.

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chad and lionbull, what kind of exhaust housings are your current turbos? divided? A/R? When do they spool, like what rpm?

 

And Chad, you should take a look at modern T3 turbos. Precision has turbos like 6262 and 6265 or 6765, etc. where the first two numbers are the size of the inducer on the compressor, and the second pair of numbers is the exducer on the turbine. My 6262 is a T4/T3 with an exhaust wheel that is the same size (basically) as the compressor.

 

 

non divided, t4, ptrim, .58

compressor is .70

wheel is 63mm

precision turbo

 

I want response from my car with room to breathe up top. It is not laggy, quite scary actually.

I can't stress supporting mods and TUNING by a competent tuner enough.

As far as spooling, it is just like a 16g but my T4 accelerates like THE HAND OF GOD IS PUSHING MY CONQUEST.

Big turbos (properly sized for the application) not spooling is something started by people who, were not tuned properly and did not have supporting mods. There is no reason why a healthy G54b cannot idle smoothly and accelerate(no hiccups) like a stock car from the factory.

Edited by lionbull
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2 different turbos, one an O trim in a .58 devided tangental housing with a 57 mm compressor. the other a P trim .58 devided tangental housing with a 59 mm compressor.

 

The P wheel is more laggy by about 150 RPM, and only improves topend above 6000 RPM. Both are suable arround 3000 RPM, and really take off arround 3300, full boost by 3400. The P trim was less switch-like in it's spool up, but still similar usable range.

 

If you use too large a compressor for the turbine wheel, or too small a turbine A/R you create a lot of back pressure, which is hard on the motor. It will still make boost, and spool, but it won't make a lot of power or last very long.

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Common Garrett T3 wheels...

 

Stage 1: 1.916/2.320

Stage 2: 2.120/2.555

Stage 3: 2.227/2.555

Stage 5: 2.437/2.795

 

 

Common Garrett T4 wheels...

N 2.071/2.922

O 2.296/2.922

P 2.544/2.922

 

Even the biggest T-3 stage 5 wheel has a smaller exducer than the smalled T-4.

 

 

On another members build I know well:

 

T-3 62-1 compressor

Stage 5: 2.437/2.795 61 mm compresor @ 30 PSI = 352 HP .69 A/R

 

VS.

 

GT35R : 2.417/2.677 61.4 mm compressor @ 30 PSI = 511 HP. .82 A/R

 

One is more efficent than the other, despite similar size. The GT35R has a similar spool time as well. T-series turbo designs date back to the 50's. the GT series back to the late 90's.

 

There are a lot of varraibles to consider.

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T-SERIES turbo can't take high oil pressure either compared to the more modern units. Its starts pissin out the back seal and before you know it its rebuild time. been there...

An oil restrictor is need when running those turbos

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2 different turbos, one an O trim in a .58 devided tangental housing with a 57 mm compressor. the other a P trim .58 devided tangental housing with a 59 mm compressor.

 

The P wheel is more laggy by about 150 RPM, and only improves topend above 6000 RPM. Both are suable arround 3000 RPM, and really take off arround 3300, full boost by 3400. The P trim was less switch-like in it's spool up, but still similar usable range.

 

If you use too large a compressor for the turbine wheel, or too small a turbine A/R you create a lot of back pressure, which is hard on the motor. It will still make boost, and spool, but it won't make a lot of power or last very long.

 

 

I like the full mounty non divided.You are right on the top end of the p trim. It never lets up but I don't think it's even a little laggy at all. I read up on the O trim and decided it's characteristics were not enough for this motor. Once I get a few dyno runs I should be able to post the charts so we can see just how good it is. Again the motor has to be tuned right(on the street). I believe it give a more accurate temperament of the car, turbo supporting mods and you can tune according to this and make changes to make the car more responsive.

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T-SERIES turbo can't take high oil pressure either compared to the more modern units. Its starts pissin out the back seal and before you know it its rebuild time. been there...

An oil restrictor is need when running those turbos

 

 

mine is fed with a -3 line

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my turbo has no oil problems, I run it straight from the filter housing that regularly sees over 100psi. -4 line and all. And I get full boost around 4200 rpm with my .82 T3 housing. I was doing some reading and that size t3 is around the same as a 1.00 A/R t4 divided housing. So your smaller t4 housings allow you to spool up faster. I'd love to see a dyno plot with boost, torque and rpm and a list of mods to the head and what header. If you guys can ever get one, let me know!
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And I get full boost around 4200 rpm with my .82 T3 housing. I was doing some reading and that size t3 is around the same as a 1.00 A/R t4 divided housing.

 

you know how A/R's work right? it's the opposite of what you just said. the deviding area takes up only a very small area. my small devied T4 is a lot larger than a large T3.

 

if you start seeing blue smoke on boost despite no shaft play, you'll know the rear seal just took a dump. good luck.

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mine is fed with a -3 line

3AN don't mean nothing. Those turbos don't live very long with oil pressure over 50ish psi or too much volume. At start up and over 3000 RPM, a healthy motor makes way more pressure than that.

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Then why does your HUGE .58 t4 spool 800 rpm before my .82 T3 does? Compression differences don't matter, my EIP cannon made the turbo spool 200rpm later than the magna, I have a 292 cam.

 

 

Why does it spool faster? who is to say? it might be the tune.

You once said you tuned on the dyno to 400+ right? If it was on the street your car would spool that .82 faster

Should of done it on the street. You don't drive on the dyno so why do all your tuning there?

I have a new stock mechanical cam, hd springs, new mech arms, new adjusters.

i do not believe in t3 exhaust for these cars, non divided full t4! just do your homework on the sizing.

 

It is not a hp race...

Edited by lionbull
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you know how A/R's work right? it's the opposite of what you just said. the deviding area takes up only a very small area. my small devied T4 is a lot larger than a large T3.

 

if you start seeing blue smoke on boost despite no shaft play, you'll know the rear seal just took a dump. good luck.

 

How much time?

I will look into a restrictor or call up Precision to see what they have to say on the oil pressure

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