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Join Date: Apr 2004
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Thanks for the book list. Much appreciated.
The engine they are working on is a V10 Diesel wich gives ~2000HP at 4000 rpm. The boost pressure is 10.5 Bar, reduced from 12.0 Bar. Some serious stuff. http://www.teamdingo.dk Unfortunately the web page is in Danish, but I doubt that will give you much trouble ;-)

Thanks,
Michael
Old 10-03-2004, 07:42 AM
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Hey beep, where did you find those headers, they are gorgeous? I've never seen them before either.
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Old 10-03-2004, 09:21 AM
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Wo ist die Rennstrecke?
 
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Those headers were made by Marco Manzie in Ft Lauderdale. The are 1 3/4 primaries for custom 3.55L 930.
Old 10-03-2004, 06:07 PM
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Goran, I went through a ton of math (not my strong point) and came up with:
35.8 lb.min @ 7000. 31.01 lb.min @ 6000. 26.73 lb.min @ 5000. 20.85 lb.min @ 4000. 16.04 lb.min @ 3000. at 1.bar and presure ratio 2.01 with a 80% volumetric efficiency. I used some charts to get some of the info (I'm lazy) so the numbers may not be exact. Do you think I'm close?

How important is the 3000 rpm point as it's pretty close to the surge line.
I'm looking at Gt30R and Gt35R maps but I'm not sure where the points should end up.
Thanks Randy
Old 10-05-2004, 12:55 PM
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Pics of headers and intercooler:
Old 10-05-2004, 01:25 PM
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Wo ist die Rennstrecke?
 
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You have a KKK flange on your headers, so in case you plan on replacing it, a Garrett will not fit. For the motor you are building, the HP you want to make and you seem to be staying with CIS, the K27 7200HF is probably your best choice. Your biggest concern should be how you are going to feed that 3.4L motor enough fuel to maintain 12.2:1 AFR. A stock Euro fuel head might supply enough fuel, but the stock WUR will not deliver. You WILL be running 14.0:1 AFR which will melt that motor in a short amount of time.

The other issue is the IC. Is it big enough to pull the heat out of the charge to reduce the possibility of detonation? What kind of cubic feet will it flow? Big turbos flow a lot of air and since you will tracking the car, you will be blowing a lot of hot air thereby increasing cylinder temps and EGT's.

I am going through the same process as you, however I am going to EFI. I will install 8.0:1 pistons, 3.4L cylinders, stock rods, hybrid 964 cams (higher lift/duration), 3.2L manifold, crank fire ignition, Kokeln IC, custom equal length headers with dual wastegate dump pipes and garrett T61 .71AR turbo. This will replace a CIS motor with a HF turbo that produced a reliable 410rwhp at 1.0 bar. I chose the T61 with a .71 AR because it had the best map for what I wanted - good efficiency to help the Kokeln IC (which flows +900cfm). The T61 will flow 52lbs at 1 bar around 74% efficiency.

If you are interested, there is a turbo calculator available on the web that can help you decide based on numbers. The HF is good to 550 hp and will bolt right up to your headers. More importantly, it was designed for a CIS system and is proven to 450rwhp with similar mods.

Good luck.
Old 10-05-2004, 04:02 PM
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Beep those headers you posted are the best looking headers I have ever seen! Just messing with you those are my headers I am putting a custom 74mm turbo on those bad boys.
Eric Hood
Old 10-05-2004, 07:33 PM
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Eric, did you run a c2 intercooler at one time? Do you think it's going to work on my engine ok? Do you have a k27 hf?
Thanks Randy
Old 10-06-2004, 07:17 AM
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Quote:
Originally posted by Lensart
Goran, I went through a ton of math (not my strong point) and came up with:
35.8 lb.min @ 7000. 31.01 lb.min @ 6000. 26.73 lb.min @ 5000. 20.85 lb.min @ 4000. 16.04 lb.min @ 3000. at 1.bar and presure ratio 2.01 with a 80% volumetric efficiency. I used some charts to get some of the info (I'm lazy) so the numbers may not be exact. Do you think I'm close?

How important is the 3000 rpm point as it's pretty close to the surge line.
I'm looking at Gt30R and Gt35R maps but I'm not sure where the points should end up.
Thanks Randy
My calcs on your engine:

Volume: 3400cc
Boost: 1 bar
RPM: 6500
Efficiency: 36%
Natural capacity: 95%

Calculated power: 450hp

Calculated mass flow: 35.2lb/min

Fuel flow: 100L/h

Suited injectors (80% duty cycle + 1.2 safety factor): 420cc

Suited turbo: GT30R (just plot it on pressure ratio of 2 and mass flow of 36lb/min and you'll see that you're within 72% efficiency. Raising boost to 1.6 bar will bring you to 45lb/min and you're still on 72% island.

Remeber, you won't be driving at 6000 RPM all the time but accellerating from maybe 4000 RPM. 1 bar @ 4000 RPM means 21lb/min, which would put you quite near surge line on GT35 but will pull good on GT35.

According to my calc, you should be getting sizeable boost already at ~3000 RPM using GT30R. GT35R is optimized to build boost early so it will also build boost almost as quick as GT30R but it will then take some additional revs to bring it to max boost (see the "notch" on surge-line on GT35). GT35 will give you extra power on the top and room to grow but also worse spoolup and bad low-rev response. GT30 will give you very driveable and responsive 450hp engine without breaking a sweat.

Your headers look very good and will work well in this application. On turbocharged cars, equal length headers are of less priority compared to short/heat retaining headers.

I still believe there is power/response to be won by using modern ball-bearing turbocharger. Re-welding of flange shouldn't bee too complicated/expensive.

Good luck!
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Old 10-06-2004, 09:02 AM
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Goran, thank you for taking the time to help us. I respect your advice. I see no problem with a new flange. Of course Henry is the builder and I will trust his choice on the turbo and cams. But I like the idea of a modern Garrett and will start looking for a GT30R and see what they cost.
Thanks again, Randy
Old 10-06-2004, 10:28 AM
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Randy the c2 intercooler is fine for this hp level. Are you going to track the car or street race it? The hf will get you into the power level you are shooting for. Similar combos to yours with less mods have made over 400 at the wheels. Yes I had a hf at one time. depending on future mods would be the deciding factor on the turbo. Let me know if you need any help. I am in Edmond saw you were in Ponca City
Eric
Old 10-06-2004, 04:47 PM
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A guy I know in california bought a GT series from these guys:

http://www.atpturbo.com/

no affiliation, but I think they have some good expertise.
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Old 10-06-2004, 04:55 PM
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Thanks Eric, we are going to build a track car for Hallett, remote coilovers, 935 type front and rear, 993 widebody +3, etc. etc. etc. Runing out of money fast! Cory Jump is helping along with Lindsey Racing wheels. My first track car build. I've built a couple of drag cars (back half, tubs, 4 links, etc.) should be fun. This fourm is a great place to get info! (as long as you triple check it. ha!)
We may go EFI next year (if I survive 400hp @ 2200#s) and would like the turbo to handle that, as long as it is not a compromise now.
Thanks Randy
Old 10-06-2004, 06:12 PM
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Holset?

I am new to this web site and do not know anything about turbo charged porsches, but do have some experience with high performance diesels. I have been using Holset turbos for my diesel performance and was wondering why Holset has not been mentioned in this thread. I have know idea if Holset makes a turbo for the Porsche application, but thought I would ask.
Old 10-07-2004, 06:39 PM
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Holsets have been used on 2.3L gas volvos with success, so I would guess there is an application for a ~3-3.5L gas engine with 911 like flows. I just haven't seen anybody do the compressor map plotting nor have I done it myself.
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Old 10-07-2004, 08:26 PM
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Diesel-rig Holsets have been used on drag-racing engines with sucess. Good thing about them is that they are cheap and flow lot's of air.

Unfortunately, they suffer from same problem as diesel Garrett's: they are built to exact specifications to please truck manufacturers as this is where turbo manufacturers make real money. With other words, A/R's, turbine sizes etc. are made to maximize efficiency and longevity on typical truck engine that revs from maybe 500 RPM to 2000 RPM. They are often very heavy so survive millions of miles.

Those kind of turbos work on gasoline engines and can give lot's of power in certain ranges but they will not provide as good response as race-spec automotive turbochargers.

I have a friend who dynoed 670hp on 2.0L four cylinder engine using Holset HX50 turbocharger, but boost comes quite late.

Engine is SAAB four banger (same as we are using but with shorter stroke) and is currently being installed into BMW Z3 Coupe:




What I'm trying to say is that you can probably get same amount of power from KKK K27 HF or some diesel rig turbocharger but what you cannot get is as good response. So don't just concetrate at achieving vertain power-level but try to make engine driveable troughout the range.
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Old 10-08-2004, 04:05 AM
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Beep,

From my experience with Holset's on diesel performance mods you are correct with the narrow range of operation. My current HX40 is lazy below 1800 rpm, but will quickly make 2 bar from there to 3000 rpm under load. However, compound turbos are becoming the standard for a wider range of boost from lower RPM, producing up to 4 bar on competition diesels . I have not seen or heard any information on compounding on gas engines, but that does not mean it has been tried. Also, the HX40 has also survived some overtemping above 1400F on several occasions. It is pretty beefy, but not a consideration on a truck. Garrets and shwitzers are getting more popular for diesels, but Holsets seem to be the standard.

I am also curious about the turbo limits in the gas engine. The EGT's are the biggest battle for diesels. Is it pressure, mapping characteristics, or temps that limit turbin applications on the porsche? Also, why not consider compounding turbos for all 6 cylinders for a wider range of mapping? Thanks for helping educate this newbe.
Old 10-08-2004, 07:55 AM
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Sounds like you could educate us by thinking outside the box. Compound turbo's, hmmm. Are you referring to multiple or single turbo's?

My considerations when deciding on a turbo for my 930 was mapping (efficiency), pressure (1 bar max) and compressor discharge temp since I am using a smaller intercooler. Using an air-cooled engine with 4 studs holding each head in place, heat and pressure are primary concerns. I have measured EGT's in the 1500 degree range under boost.
Old 10-08-2004, 12:04 PM
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Done,
My experience racing motorcycles has been that lap times are reduced exiting corners. This is where the application of power and rubber are critical. I guess I would consider the same issues if I was building a race car. Whatever RPM range your in during a corner exit is important for the proper application of power on an exit. But also, goobs of power are not necessarily good if you can not get it to the ground. In racing motorcycles the saying is sometimes less is more. So, I would consider what the absolute limit of torque your wheels and chasis could could hold on corner exits and build an engine to support that with a little to spare. If that requires compound turbos that would be fine, if not then go single. Races are won and lost on corne exits in otorcycle racing. If you get that nailed everything else usually takes care of itself.

Keep in mind I know nothing about Porsches. I just took delivery of my first 1977 911S this week, found this web sit, and here I am.

Last edited by Bietendorf; 10-08-2004 at 02:05 PM..
Old 10-08-2004, 01:53 PM
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Quote:
Originally posted by Bietendorf
Beep,

From my experience with Holset's on diesel performance mods you are correct with the narrow range of operation. My current HX40 is lazy below 1800 rpm, but will quickly make 2 bar from there to 3000 rpm under load. However, compound turbos are becoming the standard for a wider range of boost from lower RPM, producing up to 4 bar on competition diesels . I have not seen or heard any information on compounding on gas engines, but that does not mean it has been tried. Also, the HX40 has also survived some overtemping above 1400F on several occasions. It is pretty beefy, but not a consideration on a truck. Garrets and shwitzers are getting more popular for diesels, but Holsets seem to be the standard.

I am also curious about the turbo limits in the gas engine. The EGT's are the biggest battle for diesels. Is it pressure, mapping characteristics, or temps that limit turbin applications on the porsche? Also, why not consider compounding turbos for all 6 cylinders for a wider range of mapping? Thanks for helping educate this newbe.
I'm not quite sure about what you mean with "compounding" the turbochargers but I guess you are reffering staged turbochargers that "blow" into each other? It's also known as "serial turbochargers" where first turbochargers output is mated to second turbochargers input.

Diesel engines cannot "knock" (well they actually can but in the other way) like gasoline engines and some of those one-off diesel monsters can tolerate astronomical boost levels. In order to achieve those boost levels (often over 6 bars), one has to use more compressor stages as one stage can seldom achieve pressure ratio of over 1:3 (3 times the ambient pressure).

Gasoline engines are almost never fed with more than 2 bar, so one compressor stage is enough. That's why you don't see staged turbochargers on them. Also, all that extra plumbing and intercooling is pricey and complicated.

As far as I know, compounding has never been tried on Porsche engines except 959 that had serial staged turbochargers controlled by valve actuators.

There is another technique used on diesel engines by Scania and Volvo called "Turbo-Compound", where they fit power-recovery turbine right after the turbo. Turbine is mechanicaly connected to crank (trough torque-converter) and diverts some of energy stored in exhaust gases to mechanical energy. It saves up to 5% of fuel.



There is nothing Porsche-specific that limits the turbine application. Due to it's aircooled head design, older Porsche engines themselves are less tolerant to high EGT's. That makes them turbo-friendly as chances are engine itself will overheat before you overheat the turbine stage.

Diesels have lower EGT's so diesel turbochargers are often specced for lower EGT's too. With other words, you might run into reliability problems if using diesel turbochargers on some very high-strung gasoline motors.
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Old 10-08-2004, 02:02 PM
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