FRporscheman

I saw this nice 931 on craigslist, and even though it needs a new head and probably timing belt, $650 seems like a great price. How hard would it be to get a new head for this car, and how much would it probably cost? I don't think I have the space for another car, but I was curious about the 931 parts availability and interchangability.

http://www.craigslist.org/sby/car/145910945.html

924RACR

The 931 heads are unique and not so easy to replace (in terms of finding parts). But it's quite unclear what's wrong with it - did it overheat, or crash the valves??

Campeck

931's arent interference motors so they cant bend valves. atleast like the 944s can.

(edit- you race a 924 so i geuss you mean just burnt one ..nvm then!)

Mike B

I believe 931 are interference engines...early 924 models are not.

924RACR

Um, Campeck - you know what about 931s?

They are indeed interference motors. 924's (2.0L NA) are not.

chrenan

931's are interference, if you snap a belt your valves will introduce themselves to your pistons.

Campeck

oh. before i posted that i actually all of sudden wasnt so sure..so i searched the forum and thats what someone else said...sooo. whoops! now i know something i didnt.

Campeck

so how did they become interference motors from the na?
isnt it the same motor?

Andial951

Arash,

A couple threads down someone is pulling the head of his 931 since it was crashed.....maybe he is looking to sell.

95Juan

Arash, if you're looking for a 931, i know a guy that's selling his for pretty cheap.

good mechanical condition, pretty sweet. located in sacramento. shoot me a PM, and i'll give you his #.



924RACR, i'm going over to the guy's house tonight to give him your e-mail, so he can give you details.

FRporscheman

Roger and Juan, 3 p-cars of my own... I don't think I could pull it off. 924s are pretty cool though. I just searched on craigslist to see what was out there...

How big is the 931 engine, and what's the compression ratio and power? What if anything do these cars share with the regular 924/944?

924RACR

Cool. Yeah, the 931 motor is based off the 924 2.0L NA, and it is also 2.0L, but different head and pistons entirely - better-flowing head, for one. Also much lower compression; 7.5-8.5:1 depending. Power numbers: 150hp stock US, 170hp stock Euro (runs more boost, for one), 210 Carrera GT, 250 Carrera GTS, and then onward (easily over 375) for the GTR. Of course, they're no heavier than an early 944, maybe a little lighter, so they go like stink; it's also easy to raise the boost to 1 bar if you run premium (often doesn't even require adding an IC) and make plenty more power, just adding the boost controller. If you're up for some replumbing, you can add an IC of one sort or another - 951 up front, as I intend to do eventually, or CGT style on the cam cover (req's a different hood and addition of the CGT hood scoop) - and really run a fair bit of boost, probably around 18psi comfortably.

They're so cheap, fun, and fast, you can see why we often end up stockpiling them. The drawback is just that they can be quite expensive to straighten out and get running right, and ones with good cosmetics are rare.

The later/Series II (81-82) 931's got the M471 suspension as standard; it was an option on 2.0L NAs and the '80 931. The big thing there is the 5-lug brakes that were standard on the 944 and 924S (2.5L). So the vast majority of the suspension interchanges to the early 944, etc. On the turbo side, while they've got a unique turbo of course, they use a 930 wastegate IIRC.

FRporscheman

150hp? That's not bad. On the more practical side, how are they on gas economy and reliability?

Royalty

do you mean this beautiful piece fo work?

FRporscheman

How much for that thing, anyway? All this talk of 924s is making me want one...