Corleone

porshhhh951

There is a lot of GTīs with different numbers. I have choose a compressor that make air to max 450 hk. I think that a car with earlier boost and faster respons also is much quicker at the street. For now I have just started up my engine, in a couple of weeks I can tell you how it spool.

I think that most guys choose to big turbos. Why have a big one that support moore air than the engines other things like head, cam, ic and exhaust cant use. Yes the max hp can be great but will the car be fast at the street or track with a very narrow powerband? I dont think so.
450 hk with a good driveability in our cars is a lot.

The install isnīt difficult but itīs a lot of work. You need new flanges at in and out of the hot side, new waterlines and a new footings for the oilreturn flange. On a scale 1-10 itīs a 6...

TurboTommy

Tomas,
yes on a NA engine, alot of the fuel is still evaporating after the intake valve closes.
But on a turbcharged engine with more turbulence and more heat (even after the IC), a greater portion of the fuel will be evaporated by the time the intake valve closes (therefore contributing to density)
Gasoline evaporates very easily.

Aftermarket turbo kit manufacturers with low boost applications (lets say 6 to 7 psi), have found only very small power gains from the use of intercoolers, probably because of this fact.

But, like you said, it's good to strive for the best IC cooling effeciency. Then the fuel can be used to cool the combustion chamber (anti-detonation), because the charge air has already reached close to its maximum density.

Konstantin, it should be obvious that if there is an overwhelming amount of boost and/or flow being pushed through an IC, it needs to be changed for a bigger one, because THEN it becomes the weak link in the system.

Water injection cannot help in the pressure drop department. Well, it helps a bit if you inject before the IC, but then you lose a little in IC effeciency.

NZ951

I am going to go for water injection soon, I was thinking a very small injector before the IC and an appropriately sized one in before the TB... I like the idea of my IC getting cleaned out and cooled a little??? Mental idea?

Bengt Sweden

Corleone, Konstantin lives by the autobahn and drives 260+ most every day. I think your driving habits are very different so you may not agree on the perfect sertup.

Bengt

porshhhh951

Corleone....I am all about powerband. That's why I was looking at a .57ar turbine side....matted with a .70ar compressor side p-trim wheel. I think the combo would be good with the other VE mods I have planned like Lindsey Racing stage 2 head and stage 5intake manifold...I was also thinking maybe a larger TB to go with the turbo and the new manifold.

Anyways' let me know how you like it in a few weeks when you get everything together I would like to know. Pm's are fine.

Konstantin

I would say I drive many time s a day 260.
how about this?


ok if you wnat to use 1.75 bar boost then you realy need this IC. but you must do something with your head and teh studs. your head will lift.
it can not hold 1.75 bar.
Been there done that already.

ok maybe guys works 20 years on dynos but that means nothing.
It happens to work with a very succesfull Porsche racing team for years and even the chief there makes mistakes and I MUST CORECT HIM SOME TIMES:
Also since I make a master in Combustion engines and automotive engineering I can share some infos here.
I am not the Guru (not yet) but some basic things are already in my head ;-)

Ignition timing
burn up of fuel and air (combustion)
speed of burning fuel and air
way of burning fuel and air
Pressure in the cylinder
Temp in the cylinder
different temp areas in the combustion wave in the cylinder
different Pressure areas in the combustion wave in the cylinder


all of these are important.
you can not say just because the combustion speed is lower that makes LESS power.
This is more than wrong
The highe rthe octane rating in the Gasoline the slower the combustion speed. does this means the higher octane gas like 100 octane makes less power than the 92 octane??
of course not and you know that.
also who care if the combustion speed is slower.
you can just adjust your ignition timing and you already have the max pressure at the right time and you have the max power again.
with water injection you do not have to use very high retarding and that alone alows you to use high boost without detonation-> so you make more power.
And in your special case you must use it if you wnat to run 1.75 bar boost .
For the Us guys this is 25.4 PSI of boost nad not possible to run it with just public fuel. Not in our engine.
I would say if you put the same money you spend for the intercooler in a water Injection system you will get much more and reliable HP of your engine.

Engine design is much more complicated than some people thinks.
Anyone ever calculated what kind of Turbo he realy needs?
Most thisks tha a k27 is better than a k26 and of course a k29 is even better.- then a garret is betetr than a KKK and so on. nobody ever took really care of it to find out if this is realy true and why. Strange that Porsche and BMW engines made 1500 HP with a KKK Turbo with only 1.5L engine.
A K27 (the right one) flow as much as a TO4E 60 and this is more than enough to make good power.
without calculating your engine parameters like efficiency, air volume that it needed, IC efficiency, RPM, Boost you wnat to run etc etc etc you can not say one Turbo is better than the other.
same thing for the Intercooler and ALL the other "go fast" parts

last but not least
it doesent matter if I drive 80 or 260 km/h
The temp in the Intercooler is cold enough! 20 or 35 degree will not make big difference in the Power. so even if the stock Intecooler work betetr at high speeds. that means nothing . I do not loose power (not noticeble) in Lower speeds because of teh poorer efficiency in low speeds.
of course all these are for stock engine and stock boost.
if you realy want to use 25 PSI then you have to change more than an intercooler.
speak first with an real engine Builder AND an engine Engineer who understand how to build it and WHY to build it like this.

Otherwise you will blow it must faster than you think.
I hope I helped you to save your engine

Konstantin
PS your intercooler may work in swedeen but will never work in hot climates like California.

Corleone

Konstantin!

I have full respect of your knowledge and experience and everyone including myself is learning new things everyday. Thanks for your advice!

The engine is rebuilt and modified from bottom to top. My calculated boost is to start with 25 psi and then drop down to about 20 at revline.

I have a friend who has tuned a lot of race- and streetcars. He is going to help me. He has a professionell broadbandlambda, fast exhausttemp and he listens in headphones for knocks. Then Iīm going to my other friends in my hometown who has a "Rototest" (http://www.rototest.com/products/index.htm) and we are going to test my car. Of course I let you all know if you want.

P.s. Iīm glad to live in Sweden, good climate and fuel...

Konstantin

yes you are lucky to live in Sweeden ;-) This gives at least another 20 HP extra ;-))

Do NOT forget. Put other studs and a special head gasket BEFORE you start tuning and dyno the car.

Konstantin
PS of course EGT and wide band is a must.
and give us some real worl number like 100 to 200 times etc. I am tired to see high HP number i need some real acceleration times.
BTW our cup car made 0-100 km/h 3.95 sec and 0-200 km/h 12,5 sec in barcelona. I just analysed the telemetry data. not bad for only 400 HP car :-)

schnellfahrer

Konstantin; tell us a little about your speedo. Where did you get it?

Konstantin

it is from lotec
the made only one and the company no longer exists
now it is TTP and makes only Boxster and 996

Konstantin

Corleone

Konstantin!

I have other studs and a metal headgasket. I forgot.... i also have other rods.

Tomas L

I don't think injecting water before the IC is a good idea. For water to cool the air efficiently it has to evaporate. If you have enough boost you will have a temperature over 100°C before the IC and the water will evaporate (if you don't have high enough boost and temp the water will just attach to the walls of the IC decreasing it's efficiency). The water, while evaporating, may have cooled the air a bit but the water vapor also has taken up some of the volume that is availible. Remember that the volume expansion when the water evaporates is a factor of 1:1000. You should inject the water in a place so that it does evaporate inside the cylinder during the compression stroke. After the IC the temp is lower so evaporation will not occur but remeber that water is much heavier than air, if you inject it at the TB you may get uneven distribution between the cylinders as the water has more difficulty making the turn into the intake runners.

I would really like to see authentic data on pressure drop and temperature drop at full power at different speed for a modified 951.

Konstantin has a big point in that no one knows all answers and makes the correct desitions all the time. I read an interview with the technical director for one of the F1 teams and he stated that, if he got at least 80% of his decisions right, then he was the right man for the job, if not he should find himself another job.
BTW. This was not aimed at anyone particular here, just a thing to think of when you take advise from others or make your own decisions.

Tomas

porshhhh951

Thomas lot's of guy's running direct port water injection system's. As long as the injector's mists fine...the water really isint a problem with combustion. Ofcourse there are alot of kits and variables out there but, if it's done right your fine. Direct water injection is a great tool.

Bengt Sweden

Yes you can! You want to have as high combustion speed as possible. Then you can burn all the fuel at TDC and use all of it for work. What you burn before TDC works against you, so advancing ignition will help to get top pressure at the right time but you will still lose power. The limiting factor is knock resistance of the fuel.

Bengt

Konstantin

"You want to have as high combustion speed as possible"

no!!
pressure speed and max pressure is important not combustion speed.
It is the pressure that makes power not how fast the fuel burns.

Two different things

"then you can burn all the fuel at TDC and use all of it for work"

You can adjust the timing an dthe cam so can can burn all the fuel (actualy most of it) a little AFTER the TDC ( if it is exactly at TDC is not good. this is good just in theory but NOT in real world.)

Konstantin