924Board.org

[sequential]

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[-nick]

Yep, no big surprise with that response. I'm all done unless you actually have something to contribute.
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1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

[sequential]

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[Raceboy]

Here's some pics of the GTR parts, it's Peter Utzon's site:
http://www.utzon.se/gamla/937/924E.html


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'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

[Peter]

Somebody asked about PICS of a REAL Porsche Factory GTR(P,S whatever ). Below are PICS that I took sometime back. It shows the engine & piston tops. The car can also been seen at http://www.924.org/models/CarreraGTS_GTR.htm (it’s the Hugo Boss Car at the bottom of the page)

Engine Pics





It is hard to tell if the piston tops are flat or dished.

Also, they seem to rise up to nearly the block height. I don’t know if the pistons were at TDC when I took the pic.

As for the head, I can’t find any pictures, but from my memory it was NOT hogged-out. It looked stock but beefier, and that may be from all those AN fittings, block-off plates, and the fact it was very shiny.

The above Hugo Boss car was maintained by Woodcote Racing in CT. Anyone want to give them a call & ask about whether the Hugo Boss 924GTR/P/S/ car had a stock 931 head or a hogged-out 931 head?

Also, Sequential, can you go into more detail about your concerns? I am just trying to learn something not criticize your or Nick’s abilities.

I believe I understand some of your comments as:
Hogged-out head + sparkplug in stock location = combustion problems. Correct?
Hogged-out head = weaker head. Correct?
Gasket matching? From what I understand of this from researching porting & polishing and engine blueprinting for my 931 rebuild, gasket matching is the following: you place the headgasket over the head, scribe a line (w/ marker) around the inside of the headgasket area that denotes the combustion area, and just buff it with an abrasive buff to polish it and remove any sharp areas. Is this correct?

Also, I don't recall the head looking like the one on Utzon's site (pictured above), but that may be because he is building a copy with market parts rather than with original Porsche factory racing parts (read very expensive if you could even find them).

[-nick]

Wow Peter, great shots!

Criticism is great as long as there is more to it than "that won't work because I'm not ignorant". Personally, I feel much better about pulling out a few cc's, with some forethought on safety, as opposed to blindly pushing the limits of CR.

Utzon's head looks like a little material was taken out around the valves to help unshroud them. Then 7:1 CR reported in the GTR manual must come from more area in the piston.

From what I can see, those pistons appear to have a pretty shallow dish. Much less than regular 7.5:1 931 pistons. If that's the case, then those pics might show TDC. In which case, there was zero squish area in those engines.

I can't imagine loosing much/any structural integrity in the head from my carving. I suppose only time will tell on that side. It looks like Raceboy actually went deeper into the head than I did. I just rounded out the chamber across from the plug.

I also don't follow the combustion problems argument. The far corners of the pistons are still much further away from the spark plug than any point in my head.

I've only heard of gasket-matching with regards to ports. Gasket-matching a combustion chamber denotes removing _all_ the squish area. Buffing the chamber is just "polishing" as far as I've ever heard.

I don't really expect to get any insight from our "expert". We're obviously not advanced enough.
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1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

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[-nick]

Seq- IF THESE PISTONS ACTUALLY HAD QUENCH AREA you would have a point with your above stupidity. Somehow you missed the glaring fact, stated many times, that they are flat-top pistons which sit 6.3mm below the deck. The flame front has to travel all the way out to the cylinder walls rather than being contained in the dish of the piston. The flame front originates at the spark plug. Once again, explain to us why having the flame front move a marginally greater distance across the head is more significant than the much larger distance it travels out to the cylinder walls?

I'll answer it for you - you can't explain it, so you'll add some smileys and a line about "we should be friends" to try and save face. Seems everyone here is waiting for your explanations which you're simply unable to give due to your lack of knowledge.

I'd be happy if you proved me wrong, or even attempted...

ps- my pistons aren't even forged. Man you are out to lunch.
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1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

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[Chrenan]

[sequential]

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[morghen]

sequential, dude, looking at your posts...makes me think:

man, this guy is high on crack and writing on the board why do you keep making fun of -nick ? try to be coerent, precise and explain with examples and maby matematics/phisics that he is doing the wrong thing(in one post maby ?)

the only thing i'm getting here is you making yourself look smart and sling shit on -nick.

dont get all offended now please...its just an honest opinion.
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Supercharger and EFI kits
https://www.the924.com