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turbo size choice


dr_jekyll
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ok a brief setup overview.

 

4 speed auto with a01b

stand alone ecu

 

635cc injectors

9.5-1 compression ratio.

 

my question is what size turbo, it will be a generic journal baring turbo as per usual but what size

 

a t61 .68 .70 ? ive used before and had over 500bhp but was maxed

or a t76 .80 .81 im guessing it will make more power without being maxed bit at what lag cost

 

input always appreciated

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to be fair the 630cc injectors can only manage around 550bhp even then i would say they are at 90 - 95% duty

I have a t67 65 trim .68 with a 70 a/r with these injectors and was dyno'd at 524 bhp 510 ftlb at 1.3 bar and the injectors are at about 85% duty ( which is what is said to be the safe margin for injectors) so they say anyway

thats with a 3 bar fuel preasure

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I think a 67mm turbo is a perfect street turbo.

 

You will have more lag than on a 61mm, but it will still be streetable.

 

For example, my 66mm turbo makes positive boost at 3k, and starts to fly at 4.2k. This is on a stage 5 race head with 280 cams. On milder cams, my turbo would probably pull hard before 4k.

 

Regarding the injectors, I wouldn't go above 92%DC. What power are you looking for?

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to be fair the 630cc injectors can only manage around 550bhp even then i would say they are at 90 - 95% duty

I have a t67 65 trim .68 with a 70 a/r with these injectors and was dyno'd at 524 bhp 510 ftlb at 1.3 bar and the injectors are at about 85% duty ( which is what is said to be the safe margin for injectors) so they say anyway

thats with a 3 bar fuel preasure

 

this on on an na-t with 9.5-1 not the tts 8.5-1. 1bar with 550cc injectors made 510bhp with a piggyback, @44psi of rail pressure so I can make more power with less boost so the 630s should be capeable of 600+ on the latest set up

Edited by dr_jekyll (see edit history)
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I think a 67mm turbo is a perfect street turbo.

 

You will have more lag than on a 61mm, but it will still be streetable.

 

For example, my 66mm turbo makes positive boost at 3k, and starts to fly at 4.2k. This is on a stage 5 race head with 280 cams. On milder cams, my turbo would probably pull hard before 4k.

 

Regarding the injectors, I wouldn't go above 92%DC. What power are you looking for?

 

im not bothered about actual numbers per say I just want the best balance of response / punch without tones of lag but I don't want to be maxing out components

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I would look into the PT 6266 turbos or an Airwerks Borg Warner 83-75 or 88-75.

The BW had a very nice and lineair powerband compared to an old school t61.

 

The 83-75 makes 500 rwhp really easy at low boost (17psi), but the 6266 really shine on higher boost applications.

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76mm is huge Craig, that what I use to run for 1200bhp, even a modern 67 might be a bit big, they make 900bhp these days.

 

slight over kill then, so a t70 with .68 and .70 will enough for 550 on 9.5-1 compression. with a stand alone. the only reason I was thinking bigger was for lower egts and less stress.

 

all this turbo sizing gets confusing as hell, im looking at all sorts and my brain is melting.

 

I mean, whats the advantage of a bigger a/r hot side than cold side and vice versa.

Edited by dr_jekyll (see edit history)
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would this be too big/ laqggy

 

 

Inlet Size

 

4”

 

 

Outlet Size

 

2.5”

 

 

Type of Flange

 

T4 Flange

 

 

Type of Down Pipe Flange

 

3" V band

 

 

Type of Cooling

 

Oil Cool only

 

 

Compressor Trim

 

.80ar

 

 

Compressor Wheel

 

Inducer Dia.: 76.71 mm

 

Exducer Dia.: 102.36 mm

 

 

Turbine Trim

 

.81ar

 

 

Turbine Wheel

 

Inducer Dia.: 64.5 mm

 

Exducer Dia.: 74.5 mm

 

 

Applications

 

T4 turbo charger

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what about this? too restrictive ?

•Inlet/outlet 4"/2.5"

•Features wet float bearings

•1/8 NPT oil inlet

•3" V-Band downpipe flange

•Compressor wheel: .70A/R, Inducer: 91.00mm, Exducer 69.20mm

•Turbine wheel: .68A/R, Inducer: 74.00mm, Exducer: 64.10mm

 

- - - Updated - - -

 

what about this? too restrictive ?

•Inlet/outlet 4"/2.5"

•Features wet float bearings

•1/8 NPT oil inlet

•3" V-Band downpipe flange

•Compressor wheel: .70A/R, Inducer: 91.00mm, Exducer 69.20mm

•Turbine wheel: .68A/R, Inducer: 74.00mm, Exducer: 64.10mm

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The exhaust housing will be key IMO. The T61 xs turbo comes with a 69mm inducer wheel, so you can't really compare the performance to other 69mm or similar turbo's really.

 

Here's a useful thread; http://www.supraforums.com/forum/archive/index.php/t-466027.html

 

It's important to remember that the dimensions of the housings and depth will also be slightly different as well as the compressor wheel. A T70 may have the same diameter on the intake side of the compressor wheel it would definitely give more power from various design changes, the most obvious being with a .86 exhaust housing.

 

Choosing a T70 would be a bigger turbo with a similar sized inducer wheel. Perfect for that extra boost you want. This in turn should flow more air, with the same sized inducer wheel you would probably see a higher compressive force at the inducer wheel.

 

I'm looking to remove the 2.5" outlet and weld a 3" on the turbo compressor exit. Hoping it will help reduce heat and compression on the exit and increase chamber pressure faster from increasing flow.

 

On the other hand, it might crack and blow the turbo to bits LOL

 

Every one says that 3" will flow up to around 700hp. But it restricts after this. In my opinion, that means at 600hp a bigger exhaust would make more flow and in turn more power. I've a 4" downpipe and I made amazing power on stock compression so also worth considering exhaust size.

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