924Board.org

Rick MacLaren · Guest

Here's Phase I:
Prices are in Canadian dollars.

Flywheel lightened and balanced.
Exhaust and intake guides, valve seals installed. New springs.
Pistons and rods lightened and balanced and the system balanced all on the crank (i.e.,turned).
Magnafluxed
Crank cleaned and polished.
Block cylinder honed, cleaned, plugs installed.

$1100.00

Does that sound right?

924RACR · Posted: Wed Dec 19, 2001 8:20 am Post subject:

I'd like to say, but I haven't had mine done yet. However, just don't think I'm ignoring you... doesn't sound totally outrageous to me...

_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Peter · Guest

I also haven't had everything done yet on my 1980 931 rebuild, but I can give you my costs so far:
Price of disassembly of head -$0. I did it myself even though the machine shop does it as part of the rebuild process.
Price to clean all parts and check specs -$0. Once again did it myself, but included in machine shop charge for head rebuild.
Price to port & polish head and intake manifold -$40. Did it myself but purchased Standard Abrasives porting/polishing kit and a carbide deburring tip. Had compressor, grinder, etc.
Price of new valve guides, oil seals, valve cover seals-$? Don't have the bill inform of me but purchased everything from EBS Racing as per their 931 engine rebuilt kit.
Price to pressure testing head, installing new guides & seals, used valves, cam, etc, and re-cut valves, valve seats and head surface all to spec -$240.00.
Price to check that machine shop did everything to spec-$0. Have micrometers, feeler gauge, etc.
The price of having a great running 931 -Priceless (actually, its still apart, but I can make some authentic sounding engine noises as I pretend to be driving it on the track).
-Peter A. Holiat

larso · Guest

NO OFFENCE to the canadian dollar man, but is that US or CAN $$$$ bucks?

Peter · Guest

It is the New York City dollar.

bho · Guest

I can supply some insight from a West Coast Canadian perspective. Just finished my rebuild on an 81 931.

Block dipped and new frost plugs installed.
Cylinder roundness and taper checked.
Cylinders deglazed.
Head mating surface checked for warp.

Crank polished.
Crank, pulley, pistons, rods, flywheel and clutch all balanced.

Head cold dipped.
block mating surface checked for warp.
valves polished and mic'd to be usable
guide clearance checked using rocker test as per service manual.
Valves lapped. (Grinding not recommended by service manual because sodium filled)
Valves reassembled with new seals.

All totalled $900 Cdn.

Just turned 700km on the breakin this week and running well. Haven't topped 4000rpm yet to test effect of balancing.

Rick MacLaren · Guest

Does it 'feel' stronger? Any performance notes?

Rick MacLaren · Guest

Two questions

1. Cam $650 CDN!!!
What about the cam for the Carrera GT? Is it the same? (Sorry about the cross post Vaughan, but I've got a deadline to rebuild this head and I want to know about this before too long.)

2. Boring out the cylinder walls...is it worth it in terms of HP and torque? Any thoughts or results anyone can share?

_________________
1980 Porsche 931 Bitched.
1979 Porsche 924 Tweaked.

[ This Message was edited by: Rick MacLaren on 2001-12-31 08:37 ]

Zuffen · Posted: Mon Dec 31, 2001 1:16 pm Post subject:

6??|he same except further treatment to reduce wear at sustained higher rpms for the GTS and GTR,

I think the GTR has a different set of duration figures and I've got them archived somewhere

the part numbers are the same for the stock 931 and GT

_________________
Bob Dodd
14 Porsches and counting.
6 931 two of each year, including a 80S
3 924 77,77,80 all for parts
4 944 82,84,85,86 all for parts
1 sad 912 for parts

[ This Message was edited by: Zuffen on 2001-12-31 14:26 ]

Peter_in_AU · Joined: 29 Jul 2001 Posts: 2743 Location: Sydney, Australia

Hey Bob,

I'm sure there's a few guys out here who would really love to know the specs on a GTR cam.

I'd like to plug one into a 931 simulation on Dyno2000 and see if the cam really made any difference or if all the power just came from lotsa boost.

Perhaps you would consider a trip through your archives.

Zuffen · Posted: Tue Jan 01, 2002 2:54 am Post subject:

Einlab offnet 26 deg 30' v.OT
Einlab schliebt 41 deg 30' n.UT
Intake?
Auslab offnet 41 deg 30' n.UT
Auslab schliebt 26 deg 30' n.OT
Exhaust?

This is from the GTR manual.

I don't translate German well.

If anyone figures it out let me know.

Peter Utzon who owned a gtr engine has supplied a weblink. The engine that was and may still be linked on this site was sold to a fellow here in the states. Vaughn and I know the fellow and and will at some point post some pics of the GTR car and the various pieces.

I will hopefully find a quality sheet fed scanner and will dissassemble one of my GTR manuals for scanning. I'm hoping to offer the manual as a PDF download if Porsche will give permission..

http://212.181.69.188/937/RealGTR.htm

_________________
Bob Dodd
14 Porsches and counting.
6 931 two of each year, including a 80S
3 924 77,77,80 all for parts
4 944 82,84,85,86 all for parts
1 sad 912 for parts

[ This Message was edited by: Zuffen on 2002-01-01 03:55 ]

Zuffen · Posted: Tue Jan 01, 2002 3:04 am Post subject:

GTS specs

Einlab
offnet 6 deg vor OT
schlibt 42 deg nach UT

Auslab
offnet 47 deg vor UT
schlieb 2 deg nach OT

931/english spec (for translation)

intake open 6 deg before TDC
Intake closes 42 deg before BDC

exhaust open 47 deg before BDC
exhaust close 2 deg after TDC

As you guys can see the GTS at 245HP uses the same cam as the the 931.

And you can see now what the GTR spec is.

_________________
Bob Dodd - 924turbo@cox.net
931 1982, 944 1982 euro, 924S 1988SE, 93 968 tip 06 Silver Cayenne S, 06 Black Cayenne S

I have Way too many cars, parts for the 931,944 and 951

Zuffen · Posted: Tue Jan 01, 2002 3:15 am Post subject:

By the way the D-prod car uses a 931 cam.

The 931 cam is case hardened for extreme use. The 924 cam is treated but not to the level the 931 is.

This has not been confirmed in any text.

I was told the turbo spec parts are heat treated in a nitrogen gas oven where all other parts are treated in a case hardening powder. Can't remember who told me.

The cam specs are the same for 77.5> 924 to the 931,GT and GTS

_________________
Bob Dodd - 924turbo@cox.net
931 1982, 944 1982 euro, 924S 1988SE, 93 968 tip 06 Silver Cayenne S, 06 Black Cayenne S

I have Way too many cars, parts for the 931,944 and 951

TroyDest · Guest

wow, those GTR specs are sure surprising! If the degrees are given at the same opening valve lift as the other specs, that means that the GTR had 53 degrees overlap compared to 8 degrees for the stock cam. I always understood that a boosted engine wanted less overlap. What do I know!

AppleBit · Joined: 16 Nov 2002 Posts: 1516 Location: Minneapolis, MN

more overlap on a turbo'ed engine isn't always a total bad thing... depends on where you want your power...

_________________
Classic British Sports Car Restoration v6 + v8 Engine Conversion Swaps

Porsche 924 Wide Body LS1 Corvette 500 Horsepower Engine