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Thurston cc'd his 32v S motor today and posted the results on the Pac NW 928 list. I thought I'd share his info and my response here. Any comments? Math look about right?

-Adam



Your 32V S chamber volume is 64.2cc not including head gasket. The S4 measured in at 67cc's. (25.4 piston/41.6 head) Add 8.3cc's for the head gasket gives a total chamber volume for the 32v S of 72.5cc's. The S4 had 75.3 cc's. The total cylinder volume is 619.7 cc's, add the S4 piston chamber volume of 75.3cc's to this creates a total volume of 695 cc's. Divide this by the S4 piston chamber volume of 75.3 cc's yields an S4 static C/R of 9.23:1. Take the 619.7 cc's cylinder volume and add the 32v S piston chamber volume of 72.5cc's yields a total volume of 692.2 cc's. Divide this by the 32v S piston chamber volume of 72.5 yields a 32v S static C/R of 9.55:1.

Hmmm., a little better then the S4, well within the bounds of the 10:1 +/- .4 factory spec, but still pretty far from the touted 10:1 max spec.

Now, check out S4 heads on a 32V S block: 41.6 cc head + 8cc piston + 8.3cc head gasket = 57.9cc total chamber volume. Add the 619.7 cc cylinder volume for a total of 677.6 cc's, divided by 57.9 = 11.70:1 static C/R. For you forced induction fans, 32v S heads on an S4 block: 56.2 head + 25.4 piston + 8.3 head gasket = 89.9 cc's. Add the 619.7 cc cylinder volume for a total of 709.6 cc's, divided by 89.9 = 7.89:1 static C/R. Not much throttle response there.

-Adam

----- Original Message -----
From: "Deborah and Thurston" <pritchardthor@yahoo.com>
To: <PacNW928@yahoogroups.com>
Sent: Sunday, January 23, 2005 4:43 PM
Subject: [PacNW928] CC'ed my 85 heads and piston


>
>
> I will leave the math to those who can do math and have the gasket
> meashured out already. (Adam find your notes)
>
> the heads = 56.2cc
> the pistons = 8.0cc
>
>
> add gasket cc and then some fancy math and it will come to ?????
>
>
> Thurston.
>

Vlocity

Wow!

Why hasn't anyone else approached this.

So anyone out there want to trade an S-4 bottom for an 85/86 S bottom end. Looks to me like you could then mill the cylinder heads just a little to get to an 8 to 1 compression and add a nice size blower. Where is the knock sensor located on the S-4? The 85/86 S does not have a knock sensor and it would be nice to incorporate one on a blower motor.

Regards,

Ken

blau928

Hmmm,

S4 heads flow more air with less resistance. the 32v S heads have smaller more restrictive ports.. The hot blower setup will be with 968 intake valves with a GTS or 85/86 Intake Cam with S4 Exhaust cam, or better yet, grind your own cam with appropriate specs... (for street.... for track, you can do what you want based on the track setup..)

why put the heads with smaller ports that will flow less air to the cylinders... Static compression is not the only variable.... Dynamic compression and airflow are worth more consideration...

maybe I'm letting a cat out of the bag here, but, I'm not a scientist, so please, nobody believe me...

FlyingDog

Is there enough material to port the S3 heads to S4 flow? Also, how do Euro S heads compare in volume and flow?

Barry Johnson

Yes, you can actually port the S3 heads to flow as well as the S4 heads, with using S4 valves. Any bigger, I'm not sure...

Fastest928

Adam,
It get even better when you SC a 4.5 with S heads! 8.5:1 ... can you say NICE!

almost done with mine!

Marc

Vlocity

Is the difference in the compression between the s-3 and s-4 caused by the head chamber dimension or the crown in the piston or both? Just wondering if I wanted to boost my s-3 motor could I use my s-3 heads and just find a set of good s- 4 pistons....are the rods all the same?

Regards,

Ken

John Veninger

You MAY need to cut the 32V S piston valve reliefs a bit bigger for the larger S4 valves.

Lagavulin

Adam, thanks for sharing!

DFWX

Bigger is not always better in port and valve size for a street driven car.
Whoever wrote the specs above really knows their stuff!
What is the difference in the pistons for an 85 32v compared to a latter 5.0 S4?

mark kibort

How far can you bore out a 4.7 block? can you do over 100mm? wondering what to do with Scot's gouged up 4.7 liter block after it siezed. anyone need some 1 size over size 4.7 liter pistons? got 6 of them that look brand new!

be nice to get a set of 103mm pistons and use the existing rods and crank to build up a 5.4 liter short stroke GTS like short block over the winter for a size project!

MK

John Veninger

Was told 100 was about the limit for a 4.7.
104 is close even on some 5.0L blocks!

DFWX

Great info...

V2Rocket

any idea what the S3 head flows, stock?

[
QUOTE=Barry Johnson;1867120]Yes, you can actually port the S3 heads to flow as well as the S4 heads, with using S4 valves. Any bigger, I'm not sure...[/QUOTE]