924Board.org

[B]

Hey everyone

I wanted to know what anyone thought about the fitment and capability of the 951 turbo and intercooler on a 924 na with the bae manifold. I had been looking at the kkk26, t28 and t25 sized turbos to replace the original rayjay. The t28 and t25 were new (not garrett name brand however) the kkk26's were used but were reportedly ok.? I think they all spool up at around the same rpm - 2500-3000rpm - which I think will be fine for the street.
I did not know if the 951's turbo would be configured to spool up differently because of the larger motor or if it was comparable to the other kkk26 applications audi and 931. I understand the 951 has a watercool feature as well which will add to the assembly but may extend the life and durability of the turbo itself.

Any thoughts or opinions would be greatly appreciated.

Sean
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1979 924 n/a
BAE turbo
5-speed snailshell

[Scorpio]

Same setup as mine...T25 will hit 6psi at 1500 and 12 psi at 2100rpm....will hit the choke line at 5500 (65% thermal efficiency)...

I will be running a T25 but would rather a GT25 or GT28..also have a BAE

Ive also installed a 951 intercooler.....forget al the useless talk..and weld instead of screw and you should be fine

http://www.924board.org/viewtopic.php?t=27129&postdays=0&postorder=asc&start=45
_________________
1979 NA
MS1..EFI..
GARRETT T25 TURBO
BILSTEIN SHOCKS
GT BASED CUSTOM BODYKIT

Brisbane , Australia
Think mean think fast
all youll see is
my Porsches Arse!!!

[B]

Scorpio

that's a pretty quick spool time - does the choke line seem to come a little early? I was not sure.

Do you notice much delay with the intercooler?

Sean
_________________
1979 924 n/a
BAE turbo
5-speed snailshell

[ideola]

The 951 unit should be suitable from a AR perspective, as the early 951s share the same turbine wheel as the S2 931 (or so I've been told). I'm not sure if the later K26/8 versions had a different AR or not.
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erstwhile owner of just about every 924 variant ever made

[B]

thanks guys

the 951 was labeled as a k26-6 the other 2 k26 turbos were 035 145 703L and a k26 with an atl nr(?) # of 89622 0525 I do not know what any of that means yet - but I will try to find out soon. Otherwise the new t28/25 might be a way to go. The 951 has about 79,000 miles on it and I am trying to find out if it has been rebuilt at all.

thanks again
Sean
_________________
1979 924 n/a
BAE turbo
5-speed snailshell

[Martijnus]

[Scorpio]

Ill post the compressor map soon
_________________
1979 NA
MS1..EFI..
GARRETT T25 TURBO
BILSTEIN SHOCKS
GT BASED CUSTOM BODYKIT

Brisbane , Australia
Think mean think fast
all youll see is
my Porsches Arse!!!

[924OZY]

The GT28RS or Disco Potato as its also known,
is said to be the perfect size for a 2L engine,
with the best mix of minimal lag, and good power.

A friend of mine had one on his drift/ street Silvia. It made over 300kw
and went as hard as another friends 600hp+ VL turbo (RB30turbo).
When it hit full boost it was like getting kicked in the back. (Best drift car and driver I ever saw.)

A TD05 off a WRX EVO or VR4 is about the same size as a GT28RS,
flowing about 320hp@15psi

This won't become a restriction over 5500rpm like a GT25 or anything smaller.

I have 2 and may sell one.
_________________
924 N/A snailshell, superpro linkage bushes, 2.5"exhaust

4.0L ef Fairmont, 3000rpm stall, shift-kit, J3 chip, 3" exhaust, self tuned using tunerpro, soon to be boosted,
expecting 350Kw at wheels at 10psi.

[B]

do you know if that is also comparable to the k26?

thanks

Sean
_________________
1979 924 n/a
BAE turbo
5-speed snailshell

[B]

In my recent searching I have found that the original rayjay exhaust side flange is equal to the t04b or e size. I thought that is a little large for our cars but perhaps they went that route to avoid the extra heat. I was not able to find out the a/r ratio just that it is a 301FB 60 turbo. I did find that in the Hugh McInness book that that was one size that they recommended for 4 cyl. cars was a T04 size - again kind of surprising.
In speaking with one of the tech guys at turbonetics he also thought this was very large but thought that we may be able to get a t3/t04b with a low a/r - .50 might still work.
I have found a couple of 4 bolt k26's on ebay that I am still watching - I think one is from a 944 and one is from an Audi 200. Does anyone know the spacing on the k26 4 bolts?

Any thoughts?
_________________
1979 924 n/a
BAE turbo
5-speed snailshell

[924OZY]

Yes there are heaps of different sizes of T04.
They even came out on Mitsubishi Sigma Turbos.
Which have f^ck all horsepower.
Some can flow less than a 300hp and others can flow up to 1000hp
(like T04Z).
Thats from the day when there were only a few body sizes by Garrett available, and T04 technology is like 20 years old. I believe it was originally designed for a Tractor.

New style Turbos can flow more in a smaller size, which has less inertia, which will then also spoool earlier and be more efficient.
Not to mention advances in compressor wheels, which used to have blades that were all the same length but now ever second one is longer and the tip curled over for greater efficiency.
Not to mention Ball bearing cores, which are available for the T04, but didnt come out till the last decade or so.

I have a GT42 which isn't much bigger than a T04Z(which is pretty new), but still is way too big for a 2L. Probably wouldn't hit full boost till 8000rpm, if it didn't blow from compressor surge first, due to the engine being unable to swallow the air fast enough when the turbo spools to avoid a spike in boost pressure.

You would have to be carefull in selection of your T04, more in regards to the exhaust Turbine side, as these operate over a much lower range than the compressor side. There wouldn't be much point in going more than a 55lb/min compressor, as this is 500hp@1bar, and as the engine wont make this going bigger on the compressor side is asking for compressor surge issues.
_________________
924 N/A snailshell, superpro linkage bushes, 2.5"exhaust

4.0L ef Fairmont, 3000rpm stall, shift-kit, J3 chip, 3" exhaust, self tuned using tunerpro, soon to be boosted,
expecting 350Kw at wheels at 10psi.

[Joes924Racer]

What do check for in a k26 turbo to know if its in good shape or not.
Just shaft play.
_________________
1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.