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Supertec is building us a turbo motor!

We just ordered a 3.4L turbo engine from Henry to go in a race car we will be building this winter. Maybe he will chime in here and give us updates and pic's of the project. Henry is a great guy to talk to and we picked him over 5 other engine rebuilders from all over the country. We are shooting for 400-450 reliable h.p.

Specs:
Supertec 930 Hi Performance street engine.
Extras:
Port Heads 38mm in 38 mm ex
Port Intake Manifold 38mm
Supertec Head Studs
High Performance Cams (not sure yet what to use)
3.4l Pistons and Cylinders 7.5 to 1
C2 Intercooler
GHL headers
Turbo (I need help on this one, K27HF or K27 7200 or K29 or???).

Any advice on the Turbo and Cams selection would be helpfull.
Thanks, Randy
Old 09-29-2004, 12:44 PM
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I think you made a very good choice
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Old 09-29-2004, 02:28 PM
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Randy:

If you go with the K27HF, you will most likely run into overboost with the GHLs unless you modify them. The K27HF flows alot of air, and the GHL wastegate circuit is 40mm, which isn't quite big enough.

Check out turbo911.com for similar reports of this.

I built my engine recently and converted to EFI in the process. I ended up with 431.8RWHP and I think it will be very reliable.

Pics are at:
http://www.competitioncustompaint.com/rebuild/rebuild.html

I installed GHL's and the K27HF and I can easily see 1.4bar of boost through my Tial wastegate with a .8bar spring. So I can't flat foot my car at all until I get this addressed.

Brian
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Old 09-29-2004, 05:40 PM
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Thanks Brian, great job on your engine! Your advice is to pick a smaller tubo if I use GHL headers? What do you plan to do? I expect my engine to be on boost almost all the time as it's in a race car only.
Old 09-29-2004, 06:20 PM
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No I'm not saying that. I like the K27HF, and my car is a 90% track car only. I rarely drive it on the street.

I'm just saying that before you bolt on those GHL's you are going to have to modify them more than likely so that you can flow more air through the wastegate circuit of the headers. The wastegates themselves seem to be big enough, or at least that is what most people agree on, but the GHL 40mm pipe isn't big enough. And the fact that they circuit is perpendicular to the air flow going to the turbo doesn't help much.

My plan is to modify the headers, which REALLY PISSES ME OFF. I hate the fact that I have to cut a brand new set of headers. But I was told that it would all work together, and it doesn't. So that's why I'm telling you that potentially you could run into the same thing. It looks like you are staying CIS, so you may not have as big of an issue. You may be able to run .8bar and end up with just over 1 bar. But 1.4 in my case is just too much.

Brian
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Old 09-30-2004, 04:19 AM
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I beg to differ. First of all, there is nothing that says that you just have to use KKK turbochergers when building turbocharged Porsche engine. Yes, Porsche used them for a while (first turbos used Eberspächer turbochargers) but nowadays there are very good performance-turbochargers available and KKK seem to have fallen back when it comes to development of bigger turbochargers. There are very few compressor maps available to begin with...so many engines are built by using turbochargers modified according to mumbo-jumbo black magic w/o really knowing the exact characteristics of those pieces. Those (few) K27 maps I saw weren't too impressive.

I suggest looking towards Garrett's range of turbochargers. They are good, they are (relativly) cheap, they can be ordered with BB-assemblies and best of all, [b]there are reliable and comprehensive compressor and turbine-maps[/] available.

A GT40R-BB (or maybe GT35 version, if you need less headroom but more response) will cover all your needs and leave room to grow in.

Second:

The less backpressure the turbocharger represents (=the bigger the turbine, and thus the turbine flow), the smaller wastegate you need.

Exhaust gases going trough wastegate are surpluss that isn't allowed to go trough turbine, remember? So if your turbine is very small you'll need big wastegate that will route majority of those gases around.

Wastegates with diameter of 40mm and higher are quite enough most of the times, especially with bigger turbochargers. Attention must be instead payed to mating of wastegate-pipe and header collector. Exhaust gases that are required to make sharp turn to be able to flow trough wastegate will flow badly, leading to overboost-problems.

Regards,
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Old 09-30-2004, 05:43 AM
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"It looks like you are staying CIS, so you may not have as big of an issue. You may be able to run .8bar and end up with just over 1 bar."
Yes we're going with CIS for now, and I was told be Kevin (turbo guru?) that GHL is a good header to use and he recomended K27. He said start at .7 spring.

"I suggest looking towards Garrett's range of turbochargers. They are good, they are (relativly) cheap, they can be ordered with BB-assemblies and best of all, [b]there are reliable and comprehensive compressor and turbine-maps[/] available."
Henry is looking into Garrett's for me now, you seem to know a lot about turbo's I have been reading a lot of your posts. I want to choose a turbo and cam's that will work best for our engine and track. We'll run mostly on a track (1.8 miles) with 11 curves, mostly short straights (a lot of drag races to the curves). The car should be around 2000- 2200 lb.s Does any of this info matter in the selection of cam's and turbos?
Thanks for your help!
Randy
Old 09-30-2004, 06:41 AM
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Quote:
Wastegates with diameter of 40mm and higher are quite enough most of the times, especially with bigger turbochargers. Attention must be instead payed to mating of wastegate-pipe and header collector. Exhaust gases that are required to make sharp turn to be able to flow trough wastegate will flow badly, leading to overboost-problems.
beepbeep: Your point is the point I was trying to make. The GHL Collector has the wastegate circuit at a 90 degree angle to the air flow. My wastegate is a 46mm, but the pipe coming from the GHL to the wastegate is a 40mm, so there is a mismatch there.

Brian
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Old 09-30-2004, 06:46 AM
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Quote:
Originally posted by beepbeep
[B]I beg to differ. First of all, there is nothing that says that you just have to use KKK turbochergers when building turbocharged Porsche engine. Yes, Porsche used them for a while (first turbos used Eberspächer turbochargers) but nowadays there are very good performance-turbochargers available and KKK seem to have fallen back when it comes to development of bigger turbochargers. There are very few compressor maps available to begin with...so many engines are built by using turbochargers modified according to mumbo-jumbo black magic w/o really knowing the exact characteristics of those pieces. Those (few) K27 maps I saw weren't too impressive.

I suggest looking towards Garrett's range of turbochargers. They are good, they are (relativly) cheap, they can be ordered with BB-assemblies and best of all, there are reliable and comprehensive compressor and turbine-maps[/] available.

A GT40R-BB (or maybe GT35 version, if you need less headroom but more response) will cover all your needs and leave room to grow in.

Second:

The less backpressure the turbocharger represents (=the bigger the turbine, and thus the turbine flow), the smaller wastegate you need.

Exhaust gases going trough wastegate are surpluss that isn't allowed to go trough turbine, remember? So if your turbine is very small you'll need big wastegate that will route majority of those gases around.

Wastegates with diameter of 40mm and higher are quite enough most of the times, especially with bigger turbochargers. Attention must be instead payed to mating of wastegate-pipe and header collector. Exhaust gases that are required to make sharp turn to be able to flow trough wastegate will flow badly, leading to overboost-problems.

Regards,
That's a very good point made by beep. Even if you can't swing the cash for the GT series turbos, a regular garret is still better than the old fasion KKK, plus there are a ton more compressor/turbine configurations to suite the very specific needs of your particular engine. With the KKK, you'll never get it at it's peak efficiency for you individual needs. They are great bolt on upgrades for stock 930 motors, but if you building a motor and have the option of starting fresh with new headers, any turbo of your choice, and so on, then i'd go with the garret as well.
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Old 09-30-2004, 09:18 AM
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I'm new to the turbo world. If we are to pick a Garrett where do we start? What engine and or car specs do we need to take into account? I'd like to stay under $1500. Any advice?
Randy
Old 09-30-2004, 10:36 AM
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The other thing to keep in mind is that if you go with a Garrett, you may need to go with an aftermarket scavenge pump to replace the current stock scavenge pump.

Some people have had flow problems with the stock scavenge pump and Garrett turbos.

Brian
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Old 09-30-2004, 10:42 AM
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Quote:
Originally posted by briankeithsmith
The other thing to keep in mind is that if you go with a Garrett, you may need to go with an aftermarket scavenge pump to replace the current stock scavenge pump.

Some people have had flow problems with the stock scavenge pump and Garrett turbos.

Brian
Hmm...as far as I know, Garrett's actually require less oil flow than KKK's so it shouldn't be a problem, especially if you equip the oil-feed with reducer-valve.

Granted, two GT30's will be a problem (i have a friend who's 930 scavenge pump couldn't evacuate enough from his GT30 twins)...but one shouldn't make any trouble.
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Old 09-30-2004, 11:00 AM
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Randy: first step is to decide which rev- and boost range you will be using the most. You can then calculate mass flow of air (lbs/min) for that particular range and plot it into compressor maps of few different sizes of turbochargers you have your eyes on.

Goal is to keep the dot into it's most efficient range as much as possible troughout your "track pass".

So if you are going to drive from 4000 to 7000 RPM using 1 bar of boost, it's going to "eat" certain amount of air per minute (38 lbs/min @ 7000 RPM and 1 bar of boost to be exact).

Download the catalog of Garret turbochargers and check out which suits you the most. W/o really looking into it, I believe GT30R and GT35 will suit your need the best.

PM your mail adress and I'll mail you catalogs if you cannot find them online.

Regards
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Old 09-30-2004, 11:13 AM
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www.turbonetics.com
They list some of the older garret housings and there efficiencies. Beep probably has a wealth of info on the GT series.
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Old 09-30-2004, 03:55 PM
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I have some studying to do! I found the Garrett catalog and bought a turbo book. Hopefully I can learn how to use all the charts. I'm going to the races this weekend so it may be a coulpe days berfore I can get on this.

Goran, will the Garretts bolt on the GHL headers or will I have to change the flange? Will they work with the stock oiling system?
Thanks to all, Randy
Old 10-01-2004, 11:33 AM
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'bout the wastegates:




Randy: I don't know how GHL headers look like. Bigger non-R Garrett's have something called "twin scroll" turbine housing, so flange looks like this:
http://project911.luminasweden.com/log_images/168_6898.jpg

R-models (Race models equipped with ball bearings) have single port intakes, so it all depends on which turbocharger you opt for.

Turbo will work off the stock oiling system...at least as long as you have only one.

Talking about books, I bet you bought Bell's "Maximum Boost"? It's a good book
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Old 10-01-2004, 12:37 PM
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Here's example of well-done 911 turbo headers I found somewhere on internet. They should be wrapped with thermal blanket for best efficiency. Match these with GT35R, twin-plug, speed/density EFI and good intercooler and you are good for some big horsepower.



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Old 10-02-2004, 05:25 AM
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Here are maps for GT30R and GT35R with surge-lines and max boost (1.7 bar) drawn in red:



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Last edited by beepbeep; 10-02-2004 at 05:30 AM..
Old 10-02-2004, 05:27 AM
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Hi BeepBeep,

A friend of mine is into tractor pulling (in Denmark) and is playing with diesel turbos. Can you recommend other books that 'Maximum Boost' ?

Thanks,
Michael
Old 10-02-2004, 06:24 PM
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Quote:
Originally posted by mwildt
Hi BeepBeep,

A friend of mine is into tractor pulling (in Denmark) and is playing with diesel turbos. Can you recommend other books that 'Maximum Boost' ?

Thanks,
Michael
Best:

Forced Induction Performance Tuning A Practical Guide to Supercharging and Turbocharging by A. Graham Bell

Maximum Boost by Corky Bell

Also good:

Supercharging, Turbocharging, & Nitrous Oxide Performance Handbook (Powerpro) by Earl Davis, Diane Davis

Turbochargers by Hugh MacInnes


Diesel turbochargers are cheap and often used on gasoline cars. Unfortunately, they are built to withstand millions of miles and are often 50% heavier than it's gasoline counterparts. They are also customized out of factory to fit their specific application, which means that they might not be optimal for your application (turbine/compressor ratio is often skewed towards bigger turbines). Ported-shroud holes are often missing too. On the flip side, they seldom have bearing problems and are cheap and dependable.
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Old 10-03-2004, 07:30 AM
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