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best exhaust turbine for t3/t4


randy 77zt

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about 1.5 years ago i got this deal on a t3/t4 turbo from a sandrail supply place in pheonix.the compressor turned out to be a 60-1 hi-fi and the turbine was smaller than oem datsun 280zxt.so i sent it out to have the datsun exhaust housing machined and a different turbine wheel installed.car is a daily driver but is used at thunderhill 3 times a year.i am switching to sds,porting head,extrude honed exhaust manifold,65 mm throttle body,down pipe,intercooler.i want it to dyno at 330 to 350 at the wheels on a 95 degree day on pump gas .when i go to the track i run 10 gallons of union 110.last time i went to the track it was 110 degrees but no pinging on 110 gas.at the track lowest rpm is about 3500,high 6500.

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i am talking about exhaust turbine-stage 3 or stage 5?compressor side is a 60-1.stock zxt turrbine housing is being machined for turbine.i figured some of you guys have tried different turbos.who is a member of the turbo of the month club?i have another engine on a stand i can rebuild.and 2 more p90 heads and 2 more exhaust manifolds.thinking about getting an sba loan for an extrude hone machine-they want too much money and i cant see how you can get into 100% of a zxt exhaust manifoldwill be hitting p&p looking for a diesel crank this weekend.

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Guest De Schmaydee

oh yeah,

.....i had my turbo custom made for my application...i wanted something very responsive..i'm not gonna drag race it...its for road racing around on curvey roads...where i'm speeding up and slowing a whole lot.....s

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Guest Anonymous

These are explained very well in Maximum Boost or other Turbo books, but here is a 2c version:

 

The pounds of air per minute is something you determine for your engine based on RPM, displacement, and amount of boost. For example, 2.8L x 7000rpm x 1.5 x scaling constants and whatnot. The 1.5 would be 7psi boost (sea lvl = 14.7psi, x 1.5 = 14.7 + 7 (roughly))

 

Pressure ratio is the air pressure at inlet of compressor wheel to pressure at outlet of turbo. 14.7 psi boost = Pressure Ratio of 2.

 

The percentages are the effeciency of the compressor. The short of this is how much heat is added. The long is the ratio of compressed air pressure vs. Density. Want highest effeciency, of course.

 

The numbers with lines drawn across are turbine/compressor wheel RPM

 

Surge is a very naughty area of compressor unstability.

 

So, the goal is to look at your RPM range you want power in, the amount of boost you want (pressure ratio), and try and get all of that in a high-percentage efficiency area and stay away from surge.

 

I think that's all right. Others chime in if i made a mistake.

malebitchslap.gif

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Guys before you go into COMPRESSOR sizing speech, he is staying with the 60-1 hi fi COMPRESSOR.

 

Randy is dealing with the other half of the turbo EXHUAST TURBINE size. A stage III turbine should be find somewhere in the .63 to .69 a/r ratio. One optiion you could do is leave your tiny turbine alone, get a big external wastegate. When you have a big bypass, the restriction will not be very much restriction at high load conditions. Be sure to get manifold & turbine housing ceramic coated (increased heat to the wheel means better spoolup time).

 

I wouldn't go stage v on a road race car, that is more suited to a drag application.

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Cool, Thanks gravy. I have TurboCalc which will give me the lbs of air required, and I had guessed the % was the efficiency of the compressor, but I had no idea what the pressure ratio and those lines with numbers accross them were.

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i really dont want to weld on stock exhaust manifold because car will be used for a daily driver and i am afraid of cracking.the turbo bolts on with tight clearence on compressor.main point to question is stage 3 or stage 5 turbine?track rpms run from 3000 to 6500.i am looking for 350 hp at the wheels on pump gas.i run race gas on track for motor insurence

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Guest Anonymous

Stage 3 should be plenty for 350 whp. When I talked to Turbonetics about my new turbo, they suggested a 3 for street use and said it would be plenty for 500-550 whp. :eek: Possibly much more with the right wastegate design.

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Guest De Schmaydee

randy,

...you dont really need to weld the wastegate flange on the manifold...you can get (have made) an extender...like: it bolts to the exhaust....goes out 2"-3" and the turbo bolts to that...your flange welds in the middle of the extender...it can also help you w/any clearance probs and make it easier to work on (the stock turbo is a mother to get on/off)......but external wastegates arent cheap and are alot more work to get put on.....i have a turbonetics deltagate2....what are you wanting to use the car for?...drag? road?.....s

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the turbo is done-its a stage 5 turbine machined to fit oem nissan housing.waste gate hole was machined slightly larger too.compressor is a 60-1 hifi.i am going to get the exhaust manifold extrude honed .the head will be done by the guy that ports the heads for the toyota atlantic cars.if the housing was machined close to the turbine it wont bypass too much exhaust gas.going for a new engine by next spring.engine being built is back-up engine that came from pick&pull.it loooks like a brand new nissan reman motor.its very clean.

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