Miles965uk

Hey Tim im interested in your turbo....
Can you fit it on a 964 turbo? Also I whats the advantages and disadvantages over a K29 or even K27HF?
Thanks alot
Miles

mclaren55

I ran my GT35R for a year without any issues. Non water cooled, just oil cooled. She went to the track, and had about 5000miles on the street. Few of my buddies also run GT42R's on their street/track RX7's, which have particularily high EGT's. No issues as of yet.

Sameer

Tim,

How would you compare your turbo to the K27 high flow? Differences?

Kevin

Sameer, out of the box the compressor wheel of the GT35R is a hair over 61mm, the HF is 60.40 mm, a K29 is 55mm, the K27-7200 is 54.71mm, and the K27-7006 is 52.45mm..

The High Flow has a higher efficiency compressor wheel, however since the GT35R is ball bearing the compressor side efficiency is higher due to the fact that the clearance between the wheel and housing is tighter.. A Zero clearanced HF will be more efficient. With all things considered, the 2 units are similar..

Jean

Kevin, correct me if I am wrong but the watercooling on turbos is more a myth than reality. The water cooling benefits the turbo only after shut down to avoid cooking, and was instated only as a means to address what 90% of industry unaware customers don't do, read the manual and idle for a few minutes before shutting down to ensure proper oil cooling. People run Garretts without any kind of coolant, and run them for ages without failures, just ensuring proper idle time is respected. What do you think?

Kevin

Jean, why would Garrett design water cooled bearing housings in the mid '80.. They had to, due to driving habit of most people. We hammer it, always on boost, then shut it down. There were to many failures due to heat.. Yes, hot shutdowns cooked and coked the sealing rings..
the water that runs in the upper half of the bearing housing is designed to keep the oil temps down along with cooling/absorbing the heat transfered from the turbine wheel to the turbine shaft.. If someone want's to run a watercooled bearing housing without water, it's there decision. Purchasing a ball-bearing turbo without running H20 through it, cuts the life out of it.. Yes, as we know the GT35R uses hardened steel bearings vs the ceramic bearings as on the smaller units. These steel bearings, yes are harder, however, they transfer heat.. I wish I could show you the pile of BB units that I have in boxes that have failed early.. Here's the myth.. taking your smoking BB unit into a shop like myself, asking for a rebuild, I reply "please fork over $1500.00 again because they aint rebuildable.."

Jean

Kevin

I guess we are saying almost the same thing..that BB Garretts are water cooled because of their mass target usage in everyday fast cars or diesel ones, and because vehicle manufacturers did not want people coming back to them with failed turbos after a couple of thousand miles, it would hurt their reputation and make them loose credibility and warrantee $$$ regardless whether it is the fault of the user or theirs.

Is it better to have watercooled centers? Of course! Is it a must? Maybe not, provided you use them correctly. Installed correctly, and run within their intended speeds, you can abuse the heck out of them but give them 3-5 minutes of idle time to cool down prior to shut off and they should not fail.

I am of course not trying to debate the facts that you are stating, it is definitely not my field, and you are among the best in yours I guess I am just trying to put it differently so that people know what is the real story. Some are lucky and have turbos lasting forever with hot shut downs, others are not, BB are more sensitive and carry more heat in them, watercooling is a fool proof measure, but not a must.

I think Tim's idea is great, it is also not new stuff, and certainly a good option to consider. What scares me a bit more is using them with the inefficient CIS and having those turbos drive an engine at its maximum with sub optimal AFRs.

ngoldrich

FWIW - As one additional point of reference. I cannot swear that water cooling mine would make them last longer. However, I do let mine ide and cool for 3 mins after each run. And they still both last 20 hours.

Mine are GT25R's so not the same as the ones mentioned here...

Although, I never even thought about water cooling them. I suppose I could get a tank, lines, pump, and switch and give it a try. It would be great if that helped since I dont enjoy replacing them frequently (both for the $ and the hassle).

Norm

WERK-I

Norm,
For track, adding all that additional hardware may not be the most efficient way of extending the life of your turbos. Lines, radiator(s), pump and water would add a noticeable weight penalty. I suspect that the turbine housing is extremely hot after your runs and allowing it to idle for three minutes does not flow enough oil through the housing to stabilize the temperature.
Maybe lines with quick-connect fittings could be added that would allow you to hook up to an external water coolant system after your runs?

ngoldrich

Dave,

Interesting thought. I could indeed add quick disconnect fittings and give it a try.
Although I would have to be careful not to shock it and cause problems with a big temperature difference. Many tracks wont have running water easily accessible, so I guess I could use one of my spare cool suit tanks to circulate using that pump. I just wont make it ice cold...

Norm

A Grabau

Garrett specifies that watercooling must be used with all GT series turbos. You're off to a good start here but it's important to get some cooling to the centersection of any GT turbo. Unlike standard sleeve bearing turbos the bearing jackets on ball bearing turbos will expand in heat and cause the bearings to seize.

Whether it's an "over time" issue or something that could happen immediately is up in the air. We're a GT dealer and have spoken to Garrett and Tial Sport several times on this issue.

As an aside to this issue, oil pressure should be restricted to a maximum of 30psi when possible with the GT series. ATP turbo sells a restrictor fitting with a .020 orifice to create a pressure differential between the supply and return side assuming about a maximum average engine oil pressure (what, 80psi?) The limitation is intended to keep the bearings from washing and floating which will cause the turbine and compressor wheels to slow down, lagging spool time.

Alex
dent sport garage

JBrown

when i am just driving around and not on boost when i come to a stop i just turn off theh motor. if i am beating on the car i let it run for a while to get cooloing to the turbo. should i always let the car run for awhile after driving? I though if not under boost while cruising around the temp would be fine, am i wrong? thanks JOHN

Kevin

John you need to allow the engine to idle prior to shutdown.. 2 minutes will extend the life of your turbo..

TurboTim

Kevin, It is not just about size:^) It is about design.The GT wheels utilize a much better design which is the key to it being more efficient then another turbos wheels.This is why some turbo companies are knocking off the GT series wheels and using them in conventional bearing turbos.

TurboTim

Like I said before, watercooling could be adapted to the 911 fairly easily.The weight penalty will not be too great if you use a small resivoir(maybe a gallon and half) an aluminum radiator(an oil cooler should work efficiently) and a turbo waterpump from a 944T. Now I would only go through all this trouble if it was a track car. For a street car I know it is not neccessary because we have run these turbos without watercooling for years without failures or problems.