Best A/R for a PT6262 T4

[V6quattro]

Hy,

Wat should by a good A/R for a Precision 6262 T4 exhaust housing?
I think the T4 .58 A.R would by the best option for a stock displacement? Anyone one here with any experience on the 6262?

Tanks

[Billman]

What are the turbine impeller dimensions for this turbo. The holset HX40 impeller (75/65mm) was with a machined K26 - 6 (approx 0.55AR) housing fairly good with good spool regarding the size of the turbo.
I would prefer though in order to use the full potential of the turbo something like 0.63 AR or even 0.70.

[V6quattro]

Hy,

The turbine is 72mm inducer and 62mm exducer. I was hoping for someone with experience with this turbo. There is not much info off a 6262 on the I5.

[Billman]

These specs/experience can actually be transferred from one turbo to the other since the physical dimensions and the design dictate the characteristics. I think a good compromise between spool and high HP would be something from 0.6-0.7 ar. Depending on the application smaller would be restrictive for the upper rev-high hp and large would make the spool worse but give max hp up top.

[V6quattro]

Hy Billman,

Tanks for explaining. I think going for the T4 A/R.68 would by a good option then. Looking forward to see this turbo perform.

[Billman]

I look foreword too. It should make lots of power. What is the rest of the engine setup?

[V6quattro]

Its a ABY block with 81.5mm JE pistons (CR1:8.5) and IE rods (144mm). RS2 main and rod bearings. Optimized 7A cilinderhead with upgraded valve springs and TI retainers. Cams not decided yet. I have a set 7A and ABY. 7A flywheel and AAN front pulley. All balanced of course.

Nothing special but i hope it does the trick

What do you people think about injectors? I have a VEMS ecu. Will the Siemens Deka 630 by enough? Or shall i take the deka 840cc???
I have a aeromotive stealth fuel cell with a A1000 pump. Full AN8 lines and a NUKE pressure regulator and fuel rail.

[prj]

Use Bosch EV14's, don't use Dekas...
Go for 0.82 A/R at the very minimum. This turbo is a top-end turbo, no point to choke it with small exhaust housing.

630cc is too small.

[Billman]

note that the AR is relative. 0.82 AR for a small frame turbo is not the same as the 0.82 AR for a large frame.

[prj]

Well, I am considering that it is GT35R size turbo, and I don't see why you would fit anything smaller than 0.82 on it.
If less power is required and faster spool, I'd go with a smaller turbo, but again 0.82 A/R.

[Jonnybravo]

What's wrong with the dekas dimitri ?

[prj]

After some time their spray pattern goes to cr*p. They still work at higher IPW's, but car starts misfiring at idle, if trying to idle at lambda 1.
Setting idle to lambda 0.9 mostly cures this problem, but then you're running rich at idle all the time.
The injectors are not even specced by the manufacturer to run below 1.5ms, but you need about 0.8-0.9ms to idle at 800 rpm with lambda 1.

Fit EV14, and the misfiring goes away, and car idles perfectly smooth at lambda 1.

Experienced this on multiple cars now.

[Nik0las]

I agree 0.82 AR minimum. With this large turbo you risked back-presure and brake the engine. Go for smaller turbo if you need faster spooler...

[Billman]

Everything is relative.
Go for big if you wanna max out the compressor but say goodbye to sub 4000 spool.

A80avant had on a bit bigger turbo (75/65) impeller but better design as yours with rs2 cams and had 1.5 bar at 4300 with a 0.70 ar housing.

[Thuppu]

When talking about spool here, how does this sound..? CT3B 5658 AR.84, boost starts to raise from 3000rpm, 1bar@4000, full boost 1,7bar@4800-4900. 7A ex cam and cut AAN ex cam as intake cam. Not mapped yet.