944 S2 Repair

[pauly]

Was the piston on the right machined for a 16v or 8v head Simon?

[sgl1966]

The one on the right is a 968 piston machined by Baz for 8V 2.7 head around 10 years ago after reading an article on the 3 litre he first built . Left are the Woosners .
Here is the spare liner I have , just in case . As you can see nicosil coated prior to fitting for the Woosners .
Hartech has such a good reputation and well set up to fix the thousands of broken Beetles around the world , he is not interested in getting anymore of the liners made .
I would guess Capricorn might be able to help.

[sgl1966]

Paul , found an old picture of mine which shows , left 968 , center je 3L piston fly cut for 16v and right 3L 8V piston , might be of some help.

[pauly]

Paul , found an old picture of mine which shows , left 968 , center je 3L piston fly cut for 16v and right 3L 8V piston , might be of some help.

I have wondered if the Wossner 16v turbo piston bowl is much larger, and would lower the compression too much if used with an 8v head.
.

[sgl1966]

I have had a quick unaccurate measure on depth and have 5.2mm for woosner 16v , 4.7mm modified 968 and 9mm on that experimental piston . From memory the CR with the modified pistons and 2.7 head was 8.5:1 .
The problem is the dish edge is broader with a shallow angle on the 16v pistons so you really need a bit of perspex and syringe to measure volume exactly .


I will send one of the damaged original 968 pistons Baz machined for me so you can work things out if the postman get back to work .

[pauly]

Somewhere I've seen pictures of, and the CC difference between the 8V and 16V heads side by side. I'll search for that.

[sgl1966]

42cc for 16v and 61cc for 2.7 if I remember correctly Paul .

[pauly]

Is the CR on your latest 16V engine around 8.5-1 Simon?

[sgl1966]

On the 3.2 16v I have its 8.95:1 with .40 gasket .
I did work it out with the latest engine but cant find the calculations . I will work it out again when I get a chance . I'm sure Barry got his maths right , I just assembled it .
Some modern turbo cars are way over 10:1 Cr with up to date ecu's .

[pauly]

I guess it depends what Baz's plans were 10 years ago. Closer to 9-1 CR would hopefully give around 8-1 with the 8V head?

[sgl1966]

Eagle conrods used to have an engine calculater on their website .
Enter piston diameter, deck height , gasket thickness , CC , etc and it would work it out and give you CR and piston height . Not sure it’s still on their site but plenty of others on the internet .
Then you can play around with deck height and gasket thickness to find what you need.
I have boxed up piston will stick in post tomorrow and you can compare .

[pauly]

Thanks Simon. Do you know if there's an alternative/cheaper throttle position sensor to use with the DME?

[sgl1966]

I think there was a list on here showing a 90’s Volvo one was the same but I could never track one down . Martin might know better than me .

[pauly]

Fairly sure I've read anything written here or on the other forum, and I reckon a cheap alternative turbo TPS is a myth.

[sgl1966]

Install the Vems Paul then you have more options . I believe Peep offers a different tps with his ecu kits now .