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hello ..
i have ek-with stock k20a2 and i want to boost it ..
i want to going with the stock motor around 380-400whp .

my Q is which turbo going to be the best for what i'm want.
the gt3076 or gt35r with the smallest exhaust ar ..

if someone can post dyno shit it be great :up:


Tnx .

shimi .
 

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go with a ball bearing turbo. i would go with the gt3076r over the gt3076 for the ball bearing and quicker spool over the journal bearings. i had a gt3071r and i made 426whp 350wtq at 12.5 psi. no need for the gt35r.
 

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If you only want 400hp get the 30r no point in getting 35r for 400hp
 

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You could save 500 dollars or more and get a t3/t04e. It will make enough for your goals and save you some money. You will need an equal length manifold. If you plan on making more power later on your best bet would be to go with a Borg-Warner twin scroll like these http://www.full-race.com/catalog/index.php?cPath=214_1167 and utilize a twin scroll manifold. Good luck
 

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what about the gt2871r with Compressor Specs:
Wheel Inducer Diameter: 53.1mm
Wheel Exducer Diameter: 71.0mm
Trim: 56
A/R: 0.60

Turbine Specs:
Wheel Diameter: 53.8mm
Trim: 76
A/R: 0.86
Type: Wastegated


how would be?
 

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In my opinion the 2871 is undersized for even a stock k20. I have a friend with that turbo on his 240sx sr20det jwt cams, stock extrude honed manifold and exhaust housing .68ar I believe, as well as a greddy intake manifold...he made 400whp 333tq at 20psi. Irregardless the K20 flows extremely well particularly in the high cam lobe. Due to that it may choke the the disco potato aka 2871...but it all depends where you want to make your power.
 

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i have the greddy turbo on now with 11:1 comp running 11.5psi just breaking 300hp

i want another 100hp with 9:1 comp...you think it is possible? how much boost?
 

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i have the greddy turbo on now with 11:1 comp running 11.5psi just breaking 300hp

i want another 100hp with 9:1 comp...you think it is possible? how much boost?
You will be limited by the size of your downpipe...assuming your using the 2.5" that will definitely choke the turbo above your current boost level. You should also utilize a 3" exhaust. As for the other 100 hp its not completely dependent on how much boost you run its also the amount of ignition timing and a/f ratio. On pump gas your going to need to run about 17-20 psi to achieve that goal. I haven't looked at the compressor map for the greddy turbo (20g I think) so I couldn't tell you if its even efficient at that boost level.
 

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I found this on the Evans-Tuning website. I know its a B series but it gives you a definitive difference between the two turbos.


The plans for the Evans Tuning power street car for next season has changed mainly due to the new NHRA track ruling of cars in excess of 135mph need to upgrade to a 10 pt cage, 9 sec license, neck brace, etc, etc. We were trapping 140-143mph regularly with the car at 650whp, and not even putting that power to the wheels until 4th gear. In the interest of keeping the car a true street car (running the power street class in NOPI), we are not going to add the safety equipment to the car for trapping more than 135mph. Instead we are just going to limit the power being made. I opted to change out the Gt35r on the car with a Gt30r we had at the shop. Nothing else was changed on the car except the turbo, so the comparision is what you would see changing from the 30r to the 35r, or vice versa.


Its interesting to see that Garrett rated the gt30r conservately at 500hp, and this particular gt30r produced 565whp/440tq at 32psi. Garret also rated the gt35r at 600hp, and we produced 654whp/472tq at 32psi.

The Gt30r has a .82a/r housing, and the Gt35r has the .82a/r housing as well. The torque is dropping at 32psi on the Gt30r plot due to the backpressure in the turbine housing, as well as the gt35r. We are going to swap out the housing to a 1.06 a/r and see how much more we can get out of the turbo. I believe its capable of reaching close to 600whp with the 1.06 a/r, but time will tell. The 1.06 a/r housing should be tested in the next few weeks.
 

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You will be limited by the size of your downpipe...assuming your using the 2.5" that will definitely choke the turbo above your current boost level. You should also utilize a 3" exhaust. As for the other 100 hp its not completely dependent on how much boost you run its also the amount of ignition timing and a/f ratio. On pump gas your going to need to run about 17-20 psi to achieve that goal. I haven't looked at the compressor map for the greddy turbo (20g I think) so I couldn't tell you if its even efficient at that boost level.
Of course, I will be tuning the ign and fuel. I currently have a 3in cat back, and getting a 3in down before i do this upgrade. I have bought, and I am making a custom 3in intake as well. making 300hp with this turbo, 2.5 down, 3" cat back, and 2in intake at 11.5psi

This is the turbo specs I have now,
Trust T517Z Turbocharger specs:
Compressor Trim: 50
Compressor Inducer (mm): 48.1
Compressor Major (mm): 68
Turbine Trim: 72
Turbine Major (mm): 58
Turbine Exducer (mm): 49.1
Housing A/R: 8, 10 cm2

Also, what sort of piston/rod setup do you suggest? not the cheapest, but not the off the wall amount for a piston or rod...
 

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Honestly 400hp isn't all that much power for a stock k20a2. For the longevity I would build it with rods and pistons. Wiseco pistons and blueprint or manley H beam rods. But in all honesty I have boosted a few rsx's with just using a headgasket spacer to drop the effective compression ratio to around 9.5:1 which is good for what you are doing.
 

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Honestly 400hp isn't all that much power for a stock k20a2. For the longevity I would build it with rods and pistons. Wiseco pistons and blueprint or manley H beam rods. But in all honesty I have boosted a few rsx's with just using a headgasket spacer to drop the effective compression ratio to around 9.5:1 which is good for what you are doing.
i have a z3 with 11:1, with a gt2871r should i go with the .64 or the .86 a/r?

moving to lower compression and rods...what do you think?

what is the a headgasket spacer? could you post a link? would that drop my motor anything...maybe to 10:1 or so?
 

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I found this on the Evans-Tuning website. I know its a B series but it gives you a definitive difference between the two turbos.


The plans for the Evans Tuning power street car for next season has changed mainly due to the new NHRA track ruling of cars in excess of 135mph need to upgrade to a 10 pt cage, 9 sec license, neck brace, etc, etc. We were trapping 140-143mph regularly with the car at 650whp, and not even putting that power to the wheels until 4th gear. In the interest of keeping the car a true street car (running the power street class in NOPI), we are not going to add the safety equipment to the car for trapping more than 135mph. Instead we are just going to limit the power being made. I opted to change out the Gt35r on the car with a Gt30r we had at the shop. Nothing else was changed on the car except the turbo, so the comparision is what you would see changing from the 30r to the 35r, or vice versa.


Its interesting to see that Garrett rated the gt30r conservately at 500hp, and this particular gt30r produced 565whp/440tq at 32psi. Garret also rated the gt35r at 600hp, and we produced 654whp/472tq at 32psi.

The Gt30r has a .82a/r housing, and the Gt35r has the .82a/r housing as well. The torque is dropping at 32psi on the Gt30r plot due to the backpressure in the turbine housing, as well as the gt35r. We are going to swap out the housing to a 1.06 a/r and see how much more we can get out of the turbo. I believe its capable of reaching close to 600whp with the 1.06 a/r, but time will tell. The 1.06 a/r housing should be tested in the next few weeks.
what motor is that? k20/k24? what compression? thanks
 

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I can say for 400whp on a Stock k20a2 is easy. I made a little over that partially tuned on my k20 with a 100% stock motor, I had fuel issues which is why we stopped at 400whp, gt3076, Peakboost kit, 3" exhaust. This was in 102degree weather, 87% humidity, with only 1 hour of dyno tunning. I daily this setup and I have driven it without issues for the last 7 months.
 

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i can say for 400whp on a stock k20a2 is easy. I made a little over that partially tuned on my k20 with a 100% stock motor, i had fuel issues which is why we stopped at 400whp, gt3076, peakboost kit, 3" exhaust. This was in 102degree weather, 87% humidity, with only 1 hour of dyno tunning. I daily this setup and i have driven it without issues for the last 7 months.
nice how man psi where u running on i tink thats great number for a stock k...
 

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nice how man psi where u running on i tink thats great number for a stock k...
well, at the time I was running up to 15psi but I never really tuned for power at all (didn't tune cam angles nor ignition timing) but instead only tuned for boost control and some A/F tuning. I was running into fuel issues (I got bad gas on the way to the dyno and my RC750's were maxed out just over 400whp so I detuned the car to 400.

Here is a dyno, the 350whp number on the chart was when the car came unstrapped from the dyno in mid pull so we had to cut the pull short, it was actually the last pull.

 

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Good stuff!! I'm learning alot from the posts please tell me more! My excact goals are 400 whp. With a low 12 1/4 mile.
I'm running a k20a2 looking to pick up kpro next week, arp head studs, and cometic 3 layer head gasket. What is needed with the kit, what should i be looking for.

Thanks.
 
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