RajDatta

Even though I don't have any dyno numers, Chris Cervelli created the setup on my car to build 465rwhp at 1.3 bar. I don't plan on running such high boosts and have limited boost to .8-.9. I should be close to 400hp. I was running a Milledge cam earlier so I might lose some hp now. I recently swapped the cam and should have the car ready for testing in the next month or so. I need to get it dyno-tuned for the new cam as well.
The turbo S head was more for torque and not for HP so I expect a turbo S head to make gobs of torque down low but tail off on hp. The 2.7 head will make more power up top at the cost of losing some torque down low.
Chris Cervelli called the turbo S head "piece of crap" because for his race application he saw it as a major disadvantage. He swapped to a 2.7 head and right away picked up atleast 30hp. He never took any torque readings so he didn't know if and how much torque he lost.
I ran my previous setup with a K27/11 turbo and while it had good power, it dwarfs in camparison to the GT30 setup I run now. Its apples and oranges when comparing. One is latest technology and one goes back to the 70's. They are very reliable turbo's but dated.
I ran with a GT-3 no problem and was able to pull on 996tt's with my current setup.
Thom, I remember you posting in the past that you weren't too impressed when you sat in the factory turbo S. Can you share that experience with us?
Thanks in advance.
Raj

Thom

Porsche designed the 968 TS/TRS head with those somehow famous "strangled" exhaust ports in order to comply with the ADAC-imposed power-to-weight ratio, otherwise the car would have been too powerful (!). If they indeed were about spending money into developing a proper head, I think they would have adapted a 16V head, but that did not comply with the ADAC that allowed only two configurations : turbo with 8V head or NA with 16V head.
Some respectable engine builder named Chris Cervelli once declared here he made around 30 more bhp by just swapping the original TS head to the 2.7 head out of 968 TS engine. I think this can be understood as a serious performance advantage of the 2.7 head against the original TS head.

Edited : I had not noticed that thread had run into two pages, and had not seen the two posts above before posting. My bad

Thom

Hi Raj,
I was somehow impressed but the car did not feel as fast in pure acceleration as I had expected it to be. It was therefore a disappointment.
I expected the car to feel like a beefed-up 944 turbo with the old school binary power delivery and the sudden acceleration when the turbo spools up, but it was in fact very linear. There is a wall of torque coming in at around 3000 rpm that keeps somehow constant up to 5000 rpm (the owner did not rev it further), but no very sudden acceleration à la 944 turbo. It reminded me of a 928 S4 in the way the power is delivered : lots of torque on a wide rev band.

I am not sure a stock 300bhp 944 turbo Cup would be slower, but there was no opportunity to clock both cars that day.

Konstantin

a 944 turbo with 360 HP is slower than a 968 Turbo S at least till 180 km/h (113 mph)
Over this speed the 944 Turbo is faster.

Porsche DID developed a 16V engine for the 968 Turbo. I saw a complete engine at Porsche and this engine still exist.
I know also of some Porsche 16V Turbo heads for the 968. you can buy one if you have the money.
No problem with that.
The ADAC Cup was better to drive with more HP at low RPM. The 16V delivers exactly the oposite more Torque at higher rpm but less torque at low rpm (where is needed)
So they decided to throw away the 16V and use the 8V
Also the 16V had heat problems.
even with the 8V head Porsche had to put a restrictor in the 968 Turbo Rs sinc ethe car still was faster than allowed for the ADAC GT cup

Konstantin

Thom

Well, maybe the car I went in did not work well, who knows ?
It was the only 968 TS I ever went in, so I cannot judge if it actually felt as it should have.

Yes, I heard that from someone who also told me funny things about your 968 TS "prototype". The equation reveals a spin doctor but I haven't figured out yet who it is

dynatech

great thread guys keep that info coming, I’m pretty sure that you guys would have to know more about these cars than most, and all of you are hand's on guys also. After just replacing my 16 valve cams, i may just go with the 2.7 ltr head when and if i ever get some money to finish the job. i have collected a lot of the parts needed to convert the 16 valve three ltr into a turbo motor but raj is slowly convincing me (unintentionally) to just go with the 8 valve and have less hassle with the fab work, I’m really not looking to make more than 400-430 bhp anyways. could someone please tell me what i would expect to pay for a 2.7 head and are stock valves good enough to get the job done. Sean and i have a spare 968 motor that i would build up the bottom end with so i think i can do it fairly cheap and sell all of the 16 valve parts to help offset the cost a little.

RajDatta

Well, what someone needs is really up to them. Its not something someone else can make a call on. It also depends on someone's ability. Chris is a very good and a very fast driver and he needed more than what the factory setup offered. Big difference between 465rwhp and 400hp, big difference. Also, as far as acceleration, there are no documented numbers on either setup so it would be hard to tell which one is faster. To each his own.
BTW all manufacturers hire engineers, not just Porsche.
Thom, you have some very interesting information on these cars, keep it coming.
Scott, I never said anything about turbo-charging . The price for the 2.7 head is dependent on what is done and needs to be done. I have seen them all over the place.
Raj

Miles968

Hi Konstantin,
Yes mine #'s are at the flywheel. I got a few extra Hp's by going with a stand alone computer that takes advantage of and preserved the Variocam
Regards
Miles

chilibluepepper

968TurboS - What Millege cam were you running before? What cam did you change to, and why? I am getting closer to assembling my own 3 liter engine based on an S2 block with the Mahle 3.0 turbo pistons, and a 2.7 liter head. I have received several recommendations to go with a Millege cam, that is the reason I am wondering about your experience, and decision to change.

RajDatta

Alex, I was running a stage 3 Milledge cam. It is more for a track setup as it requires 1100rpm idle. It is lumpy at idle due to higher lift and duration. Also, it adds additional 20hp and moves the torque band to the right. My car is strictly street and I wanted to move the torque band to the left a little.
I was getting maximum boost at 3500-3600rpm earlier but now with the new cam, I get full boost at 3200-3300rpm. Its a nice improvement for a street car but I know I lost some up top. My engine runs a heck lot down low in the rev range so its harder for me to justify higher revs. Now, if I was tracking it, it would be a different story.
Send me a PM if you need further information.
Raj

Konstantin

Hello
I see a lot infos here (though nothing new) but not to much about my question :
HOW many HP?
also when does your cars starts make boost (at which RPM) and how long does it takes till they make 1 bar boost and at which RPM.

my car starts make boost at 1800 rpm and (I think ) it has 1 bar at 2800 rpm. It takes about 2 sec from zero to 1 bar boost.
My wastegate is not very good so I will replace it and I expect better results

Konstantin

MySwiss

Konstantin . Once you fix your wastegate, it would be interesting , if you went on the dyno and shared your toruqe, RWHP and boost numbers. That way we could find out what the stock 968TRS really puts down.

Concerning the#3 Milledge cam , it's true that it will help get more rwhp on the top end, but a good header design, intake and head work, will make a big difference on the RWHP numbers, when it's combined with the cam. Just look at my numbers that I got 415rwhp at 18psi on a 2.5L is possible...... .

I'm sure that some of you out their with the 3L 2.7 heads, can easily put down 415rwhp and 400ft/tq at 1 bar.It all depends on the headers your uing, cam and head work, combined with the right turbo.

I'm anxious to see some of you give out some real dyno charts, so I can decide to convert or not.

Konstantin

my car has 317 HP and 525 NM

Nobody use RWHP in Germany. a good dyno can convert accurate. So you can compare the HP on every dyno. we have teh same that Porsche VW or Audi use and it s within 1-2 hp on the Gt3 cup car it doesn't matter how often you check it. The HP are always withinn 1 or 2 hp.
In the USA you must guess from one dyno to the other dynojet or mustang etc etc you always get RWHP but it is alway a diiferent one sinc ethey are not able to calculate to the FWHP. So you can not compare the numbers


Konstantin

Jason Judd

That's interesting since my numbers were done on a dynojet...I wonder how they compare to others.

I thought that because the dynojet bolts to the rear hubs it was one of the more accurate types of dynos since it doesn't have to deal with friction of the tires on a roller.

Although there seemed to be some issue with the ratio that was used.

What is it that you're using that is so much more accurate.

As I said before my numbers were 323 HP and 389 TQ using this method.

Jason

Damian in NJ

Jason, the Dynapak bolts to the hubs, the Dynojet runs on rollers. I couldn't get an accurate reading with the Dynapak on two different cars, but the Dynojet much more accurately reflected what the engine puts out. I've gone back and forth with Deman about this, and I only come up with some type of software error in or inputted into his dyno.

Konstantin, maybe you can help. What does the factory estimate the drivetrain loss to be, ie what percentage of the 236hp should result at the rear wheels?