Natchamp

Kevin, I have been following this post with keen interest. As you know I have been working on my project and will be sending you my K16's shortly for your treatments. As for my project, I have the major fabrication done and am getting very excited.

Natchamp

What do you think of my air intake design?

poorb0yw

Mark -
I love the way your intakes sit to either side of the Intercooler. In fact this was exactly the thing I was thinking up for my own little project. I must say your work always looks top notch. I love seeing all your pics as you progress as it really helps to keep me motivated.

Did you hand form the end plates of the intercooler where the air enters? I remember on your supercharger you milled everything from billet aluminum. Guess that means your CNC project is still in the works?

Kevin -
Any idea of how long (mileage) the Garret Ball Bearing units last with proper water cooling and oil running through them at the same time? If they last long enough I may just use them till they break and buy new ones. Thanks again for sharing your knowledge.

TB993tt

Kevin
I defer to your experience re the spiking issue, I am not likely to ever be able to observe a wastegate working on a full power run - If this is what happens then it sounds likely that my turbos are spiking when I see 1.6 bar in 6th gear @4500rpm, since on a DIN bench dyno run, the maximum boost is around 1.3 @ 4500rpm.
You are saying the billet ali/titanium compressor wheels won't burst, does that also mean they won't "spike" ? Is this one of their major benefits ? Does the material the compressors are made from make a difference regarding them "going supersonic" - I don't see how but if yes then presumably you can get a higher volume of boosted air with a smaller wheel (with all the advantages of a smaller wheel) and presumably your zero clearance comes in here to allow less friction on the higher spinning smaller wheel hence no counter productive heat build up. I don't understand where the back plate comes in here, can you explain a bit more, and is it just theory or are you working on it ?
Really appreciate your responses

Kevin

Mark;

As a privateer you get a A+, including the car that you have built. I was awake this morning while laying in bed studying what I seen yesterday. I think that you need to use hard piping for your turbo inlet tubes! The negative pressure will collapse the tubing...... With the radiant heat and the -1.0 bar I don't think that they will live. Your outlet pipes are good..

TB;

Is there any way that you can post some detailed pictures of your car, suspension, bodywork and so on. It's at the top of the hill for a street driven 993TT.... If you look at the first picture, that is our billet backplate. If you look hard, you will see that the wheel is FLUSH with the leading edge of the backplate. No theory it's done...

All turbo owners please understand that friction=heat.... In the compressor housing we are compressing the air as the wheel rotates. If you study the wheels, look at the aero tip on the billet wheel, that is the height from the base of the wheeel to the tip of the major (largest diameter) It is 1/2 the height of the T28 wheel and K24 wheel. As a result the air get compressed even greater=more heat. If we superheat the air at the housing to temps close to 350 degrees, cast aluminum wheels get soft and fly apart. I see this happen weekly and I will post you folks a destroyed wheel. At sea level the turbo's will spin at lets say X speed, if you get to 13,000 feet the air is dense and your turbo will be spinning 1/3 faster, just to keep your engine running at the normal RPM's. Air is dense, turbo's work harder and spin faster=burst! Where I am located, we have 2 mountain ranges and it is a very common sight.

Engineers have developed the internal wastegated turbo's with a important feature, maintain constant shaft speed. This allows the turbo to be closer to keep spinning versus having surges from upsteam wastegates bleeding off all the heated energy. TB, The perfect design is to spec out a turbo that can maintain the desired boost levels that max out you engine torque numbers without lifting our heads. Most turbo's that are available can only reach those levels through overspeed spikes. Unlike trying to obtain a unit that can run all day at 1.4 bar. You are correct with the zero clearance goals.

Princeton;
A little advice, sell them on ebay.... If you launch a compressor wheel, you will be scraping aluminum off your pistons. H2O cooling is a pain on our cars.

TB993tt

Kevin
Sorry I am still a little confused about a couple of things;
You are saying that the billet wheel heats up the compressed air more than the other wheels, is this desirable, I thought we wanted to keep the air as cool as possible on the compressor side?
Secondly you say:
"The perfect design is to spec out a turbo that can maintain the desired boost levels that max out you engine torque numbers without lifting our heads. Most turbo's that are available can only reach those levels through overspeed spikes"
The K24s on my engine are easily able to produce 1.3+ bar in the mid range and 1 to 1.1 bar near max power, indeed as I have posted before, my set up, with a Secan intercooler is capable of a DIN 570hp which equates to about 1.1 to 1.15bar at max power - it is not a turbo issue but an intercooler one. I know for the GT2 Evo motors for racing with Secan intercoolers, RS used to use the K26 basis turbo with external wastegates which could reliably produce enough boost and air volume for DIN 600 to 640hp. Surely it is not just a matter of the "desired boost levels" but of the volume of air shifted at that boost level. For example when I was doing "bolt-ons" I had my stock K16s running at over 1.1bar using an external boost controller but there was no way they were shifting enough air to produce over about 440hp.
Please persevere with this thread, it is educational

Kevin

TB;

As we increase wheel speed and have compression we generate heat. So what one want to do is slow down the shaft speed by using a larger wheel, because it will produce more air at that given shaft RPM. However most of us get greedy and want more boost, the by-product is more heat. You are correct with what you have just stated. On sustained high RPM's the K24 are at the maximum. Buy the way the larger titanium wheels will be running at a lower RPM, but do produce alot more air. Efficiency is everything, if you feel that you can live with the adjustment of torque with your K24's you can have them improved by zero-clearance and ceramic coating & porting your turbine housing. Are you running special headers?
Coat them and keep the heat in them.

Kevin

This is a picture of the finished zero clearance compressor housing... It has been dialed in and installed and re-installed in the cartridge and spun up to very high RPM's. Everything then gets taken apart and re-checked. It has been a very labor intense project but I'm really excited with the results.

J.Seven

KRA993tt, you´re right. I had their first stage turbo system on my first engine in the Boxster, it was the 2.5L unit. The system consisted in a sigle turbo aplication with water to water intercooler situated on the rear trunk, an extra coolant radiator was put in the front bumper and a water pump would circulate the coolant thrue the water intercooler and front radiator. Car was making near 300Hp, but there wasn´t any internal changes in the engine, such has new rods, pistons and so on, the result was 40.000Km / 28.000Ml very pleasant miles running with this system and than BOOMMMM ON THE HIGHWAY, engine died. Than I drop the 3.4L engine from the 996 on the same car, since September 2000 had zero problems with it, runs like a factory product. The air to air Intercooler is much more eficient, even Pitz (TTP owner) that sells both systems will tell you that.

Here´s some pics of the water intercooler installed on my Boxster. For the 993 the intercooler has a slightly different shape, although size is the same.


Here´s a much better Turbo intercooler system for the Boxster, although these 9M6 engine are not suited to forced induction.

BC

A. Graham Bell, in his "Forced Induction" tuning book, describes the Air to Air and Air to water IC efficiencies in detail. Though he may not be conclusive in the utmost way, he does tell us that with limited space, Air to water is always better.

BC

Zero Clearance.

Obviously self explanatory, but what about the added friction?

I'm interested in this idea as the centrifugal superchargers are simply the compessor side of a turbo strapped to some gears.

So Zero Clearance may work for them as well?