sand_man

I thought I'd get this one in for the upcoming weekend. I also intend to bump this one from time to time to keep it near the top.

It's no secret that KKK (specifically K27) has been the "no-brainer" turbo of choice for our engines. All things considered equal, install is straight forward, flanges don't normally require any modifications, no oiling issues, proven history, unparalleled support and knowledge from the likes of Imagine Auto and Ultimate Motorwerks, etc., etc., et al. However, once you get into the modified versions of our beloved K27 platform ("S", "HF", "HFS", "HF2") the coins start to drop...and QUICK! I realize that where performance/reliability/fitment are concerned, you have to pay if you wanna play. But the information age has brought with it a host of import "street tuners" all experimenting with various turbos. If you run a Honda or Nissan (for example), the market just seems flooded with affordable yet proven options. I'm not sure the same can be said for our 930s....P-car tax not withstanding.

I went with the basic K27 on mine because I was in a pinch and the shop didn't have any of the modified versions that I could afford on the shelf (I wanted the "S") .

So I present the questions: If a person was still on CIS with mild SC cams and wanted to run a Garrett turbo, what are the pitfalls? When it's all said and done, would I really want one? What do they cost? What are the mods needed to fit one? Once and for all, what is the proper way to oil one???? How do you read their model numbering scheme to pick the correct one? Can they be had with flanges to fit our headers and exhausts? What are the other choices?

The reason I'm so curious is that I met a guy whose been adapting various turbos from salvage yard cars (all sorts of makes and models) to his 1980s Volvo beater. It's just something that he plays with. Sometimes it's a hit, sometimes not. But the mystery of how it will run is the thrill for him. I'm not ready to bolt a turbo from a Cummins diesel to my car, but I am curious as to what else is out there that would perform, without breaking the bank.

Let's discuss...

Daley88930

Great Thread idea--I keep hearing and reading about Garrett etc. --I am all ears especially if we are talking CIS based cars.

rsrfan

I recall that Speed Force Racing out of San Diego had a "bolt on" solution for the GT series Garrett turbos for our cars. I was hoping that one of the members had tried this option but have never seen any posts to that effect.

JP

sand_man

http://www.speedforceracing.com/prod...bochargers.php

sand_man

And so the neophyte asks...what is it that's so special about Garretts? Is it the bearings? I've heard some guys say that after they turn off their engines, they can still hear the Garrett spooling down? Is this true?

Porschefile

Garrett is the biggest and most proven turbocharger manufacturer in the world hands down. Their GT series is about the most advanced production turbo lineup compared to typical manufacturers like KKK, Borg Warner, Turbonetics (most of their stuff is Garrett based anyways), etc. Their GT series has been so widely used in pretty much every form of motorsports and on all types of race-winning vehicles for years (the GT series lineup has been out over a decade). I'd really recommend researching for yourselves on Garrett's website or other forums to get an idea what I'm talking about. Unfortunately it seems like the Porsche community really hasn't largely taken too much notice of the GT series. True, there are some Porsche builders and tuners out there doing some GT setups for various Porsches, but unfortunately it seems relatively uncommon to find these setups on any of our cars. Maybe it's the fear of the "unknown" holding people back. I don't really know, it just seems like the Porsche aftermarket community can be a little resistant to change sometimes.

The "thing" about the GT series is that they have some of the most efficient and aerodynamic wheels, their stock housings are some of the most efficient and advanced compared to older stuff, their ball bearing center sections provide minimal friction loss (yes they do take awhile to spool down and will continue to spin after shutting a car off), etc etc. Except for a select few custom turbo manufacturers like Innovative Turbo Systems (ITS), Garrett's GT series stuff is true 21st century technology. A majority of other turbos since I'd say the 90's are still based on old 60's technology. Garrett re-designed everything with their GT series using new technology like uber-expensive CFD software and other computer-aided instruments to develop the most efficient stuff possible (at the time) with a production turbo (not saying they're perfect as longevity is still a concern). If you really look some of those turbos over, you'll see what I mean. A large number of GT series turbos have a cone-shaped diffuser on the turbine outlet which helps increase airflow velocity and get the exhaust flow out as quickly as possible. There are plenty of other nice examples of improvements over older turbos that might take too long to go into detail on (compressor surge housings, center sections require less oil pressure, etc etc), but needless to say they are the current defacto standard in turbochargers. The import community caught on to this long ago as they usually seem to be at the forefront of automotive/turbo technology these days. I'm hoping the Porsche community will start catching on as well. The KKK stuff really doesn't compare to these turbos.

Porschefile

Sand_man, just thought I'd use another post to reply directly to some of your other questions. There are a few things about the GT series turbos you have to watch out for. They are specifically designed to be oil AND water cooled. Running nothing in the coolant ports will result in a drastically reduced lifespan. I remember reading several threads regarding this on Pelican Parts I believe, and one guy found on his full on race 911 (twin turbo but I don't think it was a 993) that it helped to at least run oil through the coolant ports as well. I think it might have been Norm Goldrich, but I could be mistaken. Several people have mentioned also implementing a small water cooling setup in the engine bay, which is one way to do it. In addition to that, the GT series center section does not require nearly as much oil supply as their older T series stuff. It was recommended to me by a Garrett engineer (I've heard others say the same thing), that it's generally a good idea to use some sort of restrictor to reduce the max oil pressure at the turbo to approximately ~40psi. I've known people using restrictors that still allowed for ~50-60psi without oil issues, so 40psi might be a bit conservative. Either way, a restrictor will definitely be required using a GT series on a 911 however I'm not entirely sure what exact size as it really differs between different engine setups. Tim @ SFR is a good guy and has all the stuff to put one on your car if you decide to go that route. The cost can add up a bit but, IMO it's worth it as you'd be getting the absolute best components for your money. Old, modded K27's really don't compare.

As for non-GT series Garrett stuff, there are still some other options worth considering IMO. If you are really the do it yourself type, there are plenty of Garrett and Garrett-based turbochargers out there that you can find an off the shelf turbo to perfectly match your goals. The best option IMO would be a Precision Turbo turbocharger website . Their stuff is Garrett-based, however they build most of their own compressor and turbine housings (some are actually a bit nicer and more efficient/durable than the Garrett stuff), and I believe they make a few of their own custom wheels for those turbos. Their stuff is top notch, they have a huge selection in Garrett T3 and T4 class housings, and you'll still get something like ~90% of the performance of a GT series turbo, though you'll save a bit of money. IMO, for the do-it-yourself mechanic it's a good option as they list plenty of turbo specs and you have tons of sizes of components to choose from so you can really design a perfect turbo for your setup. Some prefer to just buy a proven product, throw it on and be done with it. Some, like me, prefer to get a bit more involved with the whole process and better understand their car. The only real downside I see with the KKK turbos is there is very little sizing info, flow charts, etc out there so you pretty much have to base everything off of everyone else's results. Turbo sizing is a whole other subject I could spend decades talking about, but if you are interested in discussing it Sand_man, just let me know. With all the free info out there on the net, it's really not that hard for the average car guy to spend a few hours doing some research and come up with their own custom off the shelf turbo combination to meet their goals.

Porschefile

Wow, I just can't stop posting on this thread! Anyways, I just thought I should point something out. The Garrett stuff is definitely more efficient and a bit nicer than say a typical K27, however, honestly on a CIS car the K27 still does ~80-90% of what you'd get with a more efficient Garrett turbo. Don't let that discourage anyone. IMO it's still worthwhile to do a Garrett turbo conversion for those individuals that really like to design their own custom stuff or just want to do something different. Part of the appeal, to me, with the Garrett stuff is the huge variety and large quantity of info out there regarding their stuff. I personally really like to try and design my own setups and come up with my own custom turbo combinations as that's part of the fun in building a car at least IMO. It's just not really all that "necessary" on a CIS car as from what I've seen even modded K27's (the HF series for example) can far surpass the fueling capabilities of CIS. The K27 stuff has been more than proven. True, with the Garrett stuff and especially the GT series stuff there is probably a bit of efficiency, power and spool improvement over the equivalent sized KKK stuff, but I wouldn't say that it is some phenomenally huge improvement in every case. I think the question everyone should ask themselves is if they want to size their own turbo, or if they'd just rather go the typical route with what's already known/proven. I think either way, any of us will be satisfied as a good 400+whp in these cars is sooooooooo much fun!

Oh, one last GT series point. One of the biggest and most noticeable improvements with the GT series IMO is transient response. Compared to older T series stuff and equivalent sized KKK turbos, GT series turbos can have some INSANE response improvements. To clarify in case anyone wonders, transient response is basically "tip in" response, partial throttle response, etc etc. While actual boost threshold and full boost rpm might stay relatively similar compared to older T series stuff, the big improvement is the actual physical amount of time it takes for the turbo to spin up. I can't remember the post but, a guy in the 951 community datalogged his 951 with a K26/8 and a 50trim T3/T4R (which is considerably larger, 270whp turbo vs. 400whp turbo), and the 50trim actually spooled to the same max boost of ~21psi approximately ~6 seconds faster and ~100-200rpm sooner! You really have to drive a car with one of these turbos to see what I mean. I've been in plenty of imports including some big turbo stuff with Gt40r's Gt42r's, and it's absolutely insane to see the boost gauge go from ~10psi to say ~25psi in just 1-2 seconds! Even though I risk being flamed for eternity, I highly recommend checking out some import forums as you can usually find plenty of factual evidence to prove what these turbos can do.

sand_man

...and there's my favorite avitar! I was hoping you'd chime in, Porschefile. I must confess, reading the 24 pages of "Tired of mindless waflle? Learn something " in your signature, was also the motivation for this thread.

I'm a car guy at heart! I don't give a damn if it's a Honda, a Porsche, a 1930s Ford Model A "High-Boy" Roadster rat rod, or an early '60s Beetle! If they're done tastfully and the owners are cool, I dig 'em! I've met just as many P-car c_ck suckers as I have in the "ricer" crowd. So I want to keep an open mind. I'm not talking about the import d!ck-heads that pull up next to you at the light with a turbo whistle installed on the end of their 7" diameter fart-box!

It's just that when you start getting into $1,500.00-$1,700.00 for the latest-greatest-super-duper-uber-turbo, I want to make sure I"ve covered the bases. I think the only thing holding me back regarding the Garrett when I was in need of a replacement, were the issues surrounding oiling and not knowing all of the housing designations - T03, T04, GT30, GT35, GT30R, etc. I was afraid of the unknown and the KKK was...well...as I said in my thread openener, "a no brainer".

sand_man

Geez, we might even lure Special Tool from the 951 (944 Turbo) forums, with this one!

DonE

I run a GT35r turbo on my EFI car. I do not use any center section cooling, but they way I get around this it to 1. run -8 AN line to feed the bearings, 2. ALWAYS idle for a couple of minutes to cool down, and 3. use high quality synthetic oil.

I run a line out of the stock oil feed (without the check ball) directly into the turbo. I then use a high volume scavenge pump to drain the sump.

To answer sandman's question, when I researched this very question 3 years ago, the answer from true turbo tuners was that it would work with CIS, but CIS could not be tuned to take advantage of the capabilities of the BB setup. For example, I can tune my EFI car now to reduce turbo lag through advancing spark, adding fuel and the fact that the intake is not 2 1/2 in diameter and 6 ft long. For most CIS cars, you can not tune that.

The other problem at that time was that the GT35r needed some fabricating to get it to fit a B&B or GHL pipe - no "bolt-on here. Not many people want to go through that expense for no real gain.

When I converted to EFI two years ago, bought a turbonetics T61. Wrong choice. I then sold it and bought the GT35r with a T4 flange for about $950.

bogey1

We just fitted the GT35R to my EFI converted 3.6T. Much went into it, and its still has a few non-turbo bugs to be sorted, but PHd At ImagineAuto was literally laughing when he left me a voice mail after the first road test. He has driven a ton of high HP p-cars, and he said 1st gear was a waste, and 2nd was a short session of shreading tire, and he ran out of road before the shift to 3rd. And that was all below 5,000 rpm at .8 bar. It took me demanding the turbo before he agreed not to put in another KKK, but I think he may now be seeing the light.. We will see when its done, but he is already talking about upgrading it before shipping it back to me to the 37. I can't wait.

Porschefile

The Gt35r would be a pretty darn responsive turbo for any 3.3+l f6. Technically they can squeeze out a little over 600whp on the typical water cooled import stuff I'm used to, though it usually tends to require anywhere from 28-36psi on all of the 2.0-3.0l stuff I'm used to. From what I'm learning about 911's and head temps for example, it seems like 500-550whp would be a bit more of a realistic expectation for ~20-25psi boost levels. Anyways, all of the names and numbers do get a bit confusing. For a 3.3L+ sized F6, I'd really recommend getting something in the T4 class, or with a T4 turbine housing. Anything 3.3L or above has more than enough displacement to take advantage of a T4 housing. Technically turbos like the Gt35r and Gt30r are a T3 frame turbo, however as mentioned by Don there are several companies out there (Precision Turbo does it IIRC) that will mod T4 housings to fit them.

Sand_man, if you're shooting for a specific power level, let me know and I can recommend a few turbos. I've seen a few here and Pelican I believe speculate about some slightly smaller turbos like the Gt30r, though IMO those are a bit small for the displacement of most of these motors and the typical 400+whp levels most are looking for. Gt35r's for example usually tend to see perfectly streetable response even on motors as small as 2.5L (I've experienced a few on high rpm 2.0L motors that are still somewhat drivable). I'd suspect a Gt35r with a .82a/r T3 housing or possibly a .68a/r T4 housing should see 1bar by at least 3200 if not just below 3000rpm. I'm still getting used to the whole F6 thing but, on the typical ~2.5L motors I've used these on, usually 1bar comes in at ~3.6-3.7k and the car pulls HARD from there. So what type of headers are you using? To make things easier, there are a few inexpensive aftermarket headers like the GSF ones that already have T4 flanges. I must confess I usually take the lazy way out to avoid fabrication where possible.

Sand_man, did you really go through all 24 pages? I started out in the import community, and I really love how there is such good tech info that is so widely and easily available in that community. I figured I might as well link some of that info so others here might benefit from it as I've had some futile arguments with people here on some pretty simple subjects. Oh well, you can't please them all. Don't get me wrong though, I certainly don't know it all and I know just barely enough to know that I don't know nearly enough.

Porschefile

Almost forgot, for any GT series questions, you might also contact Chris Carroll @ TurboKraft He's a really nice guy and has been doing several GT series setups for awhile now. Check his gallery section and I believe there are one or 2 cars featured with either a Gt35r or Gt30r setup, as well as dynos. Chris has some pretty sweet stuff that you never hardly see advertised for these cars (I want his AEM ems setup baaaaaad!).

bogey1

your on spot with the HP figures for the 3.6T with the GT35R. First run at .8BAR was 479RWHP. Still having ignition problems though.