924Board.org

[Rob]

hello does anyone know about stroking and uping the compression to about 10:1 or more that is what are the pros and cons and also what internal work to head gaskets, valves and pistons would need to be done in order to upgrade the comp. safely
of course assuming that you upgrade the heads to 931 ported heads etc and the intake, fuel and the exhaust
could a high ie 200+ hp power be yielded
and also where could i get a 924 NA engine stroked in australia
thanx :smile:

[ This Message was edited by: Rob on 2001-08-02 14:25 ]

[larso]

EFI (no afm, has to be crabs or maf or similar), high rpm (valve springs, rods, crank balancing, lighten stuff), lightened EVERYTHING in the engine, special pistons, very steep yet roudn cam, lightened pulleys crank flywheel, ported everything, is the only way to get the power u want.

i would get a 944 engine(displacement is easier cheaperway to HP)/or buy a 951 before i spent all that money

[Peter_in_AU]

Rob,

I've had a look thru some of my back issues of "Zoom" mag and the only Bris. shop I've found so far is perFOURmance Motorsports in Logan Rd, Underwood Bris. web site at http://www.pms.net.au/ These guys seem to be basically into stroker kits for WRXs but they might be able to point you in the right direction.

My suggestion is to check the Aussie V8 mags, the V8 guys are heavily into stroking (take that how you like) and you're likely to find a shop up there that specialises in innovative crank work.

Another option is to post a question on AutoSpeed. If you aren't a member let me know and I'll post for you.

OK, here's a brain-dump which may be useful:

Custom-built crank, probably cost you more than the whole car.

Mod the existing crank, this may be possible. What your looking at is a technique called "offset grinding". Basically they build up a big lump of metal on the "outside" of the crank journals and regrind the crank with the centre of the journal moved further away from the centre of the crank. What you want is to have the journal centre offset by 6.8mm which will give you an extra 13.6mm stroke which will give you 2304cc. Problem is that now your pistons poke up an extra 6.8mm and slam into the head. So, you need either custom rods (shorter) or custom pistons (less distance between the pin and the crown). If your pistons and/or rods are going to be replaced anyway, this may not be as expensive as it sounds. Don't know if this can actually be done to a 924 crank.

Another option that everyone has told me won't work is a crank from a VW Golf/Rabbit/Scoroco 4 cyl. 1400cc - 1800cc. If you have one of these lying around you could measure it to prove them right/wrong. If a VW crank could be made to fit it'll give you 2200cc. You still have to do the piston/rod thing.

Next step, head and cam. Standard stuff.

Next step, as Lars says, is EFI. When you look at the engine bay, all that rubber and metal bits on your right have to go. In their place you put a nice set of quad throttle bodies, electronic injectors and fuel rail. Best looking set I've ever seen is from EFI Hardware in Melbourne. Take a look at http://www.speed-technology.com/efi_throttle.html and click the 4 cylinder button. Real perty ain't they. At AUS$1033.50+GST they have to be a total bargain. Injection Perfection in Sydney also do quad bodies, see http://www.injectionperfection.com/ You'll need a set of weber manifolds made up to fit them, probably cheaper to get made than to try and buy a set.

Now a computer, my choice is a Haltech E6K - say AUS$1900 all up http://www.haltech.com.au/. This is the last place you want to try and save a couple of hundred dollars. No need to go for a Motec or an Autronic they would be total over-kill but don't think about 200+hp with a $1000 computer and don't think about stuff like a GM Delco from the local wrecker for $100 that you then have to spend $1000 in dyno time and 3 months to get working.

Clutch/pressure plate, reliable sources say that the clutch plate from a Ford Sierra has the same spline pattern. Perhaps the pressure plate can be mated to the flywheel. With the Sierra Cosworths turning between 200hp and 500hp the combination should be strong enough.

Lighten and balance stuff as you go.

As the man said, "speed costs money, how fast do you want to go?".

One "nice" thing about hot-rodding a 924 in Australia is that 944 turbos are still fairly expensive so you can make a very fast 924 for half the cost of a 951.

As soon as I get really, really motivated, I'll be doing all the above to one of my engines.

Peter.

[larso]

How much can the 924 block be bored out before it becomes weak too?

And are there any pistons for it other than the over bore ones, i mean some really overbore pistons, why couldn't you bore it out and stroker it, get it up to 2.35 litres or something.

[-nick]

i would be careful as to how high you turn the rpm's. the 924's theoretical limit is only around 7400rpm. above that and you're destroying pistons (unless you goto nos). the more you increase the stroke, the less rpm you pull out. it doesn't matter what cam/valve springs/etc you've got.

btw- the DP guys can barely push 200 reliable hp. these are on race only engines that just aren't streetable. if you go up to a 2.2+Liter, you're likely to get to the 200hp mark and still street the car. but it's not going to be without extensive time and money.

good luck
-nick

[larso]

well usually the valves get destroyed or the rods get destroyed before anything else, when I say up your rpm I mean with lightened and balanced everything, and special rods...the camshaft if properly ground with lots of roundness and lift will stop the valves from smacking the pistons, but a stock cam at 7400rpm is probably gonna make the valves float like buoys on water

[Peter_in_AU]

don't know what the actual limit is for boring a 924 but it would be very little. Just take a look next time your head is off - there's just no meat between those bores.

The DP engines were supplied bored out and they were only rated at 2039cc.

Hey Nick, you sound like you've been reading my old posts. I still think that a 200+hp NA street engine is an urban myth but I would love someone to prove me wrong with dyno prints.

[Dave]

DO you guys think I can get a 924S up to 200+ HP. I am looking into doing lots of head work like porting and bigger valves. I have heard from alot of people that you cant realy up the compression WHY NOT ???? Also I have done some minor upgrades like a stage 2 MAF kit (www.huntleyRacing.com) igntion and a adjustable fuel pressure regulater. I think some $800-$1000 of head work and headers would realy put up at the 200hp mark. WHAT ABOUT A CAM??????? Well you guys look like you could realy help me out so thanx

[-nick]

hey Peter-
i think you could get 200hp out of an na, but you're not going to be able to do it from a 2.0L. i don't think i've ever seen a streetable na engine that could get 100hp per liter. however, 90hp per liter from a 2.2, or 85hp per liter from a 2.3. i could see that happening.

good luck
-nick

[larso]

well u could get close to 200 hp, but what is the point since it is such a heavy block...with such a heavy block in my opinion you might as well just get a 944 2.5 litre or a 944 3.0 litre

[Rob]

Thank you Lars and peter from Aus
especially pete this gives me alot of stuff to think about i have been going round in circles and unfortuneately if i want a arse kicking porsche i would need to buy a 924 NA because 931's 944's and 951 aren't really in my budget as in i wouldn't be able to mod them enough for my liking
but yeah
hopefully if i do this
it will strapppppppppppppppppp

[Vince]

Sorry to burst everyones bubble. But after you get to about 145 hp with a cam and carbs with Euro pistons the car get very high strung and would not launch unless you revved to 2000 and pop the clutch. It bogs down and you will not like it. This is from experience. Do the changes in increments and you will know when to back down. If you want speed buy a 951. Little old 924s really don't rev high enough and then you have to look at the tranny and possibly change gears. Costly.
Have fun within your budget and continue day dreaming. It can be fun.

[larso]

OK, thats a good point vince...

SO If you stroke the block and bore it, will that cause it to bog??
I think that is the BIG advantage with DISPLACEMENT, is that you don't get as many SIDE effects, correct?

I would focus on getting it to 145 HP if you DON'T plan on stroking/boring it, and then make the car very light, take bumper shocks out, shave bumpers down, get plexi hatch, etc. 2600 pound daily driver car...if it isn't a daily driver take back seat out insulation and tar/wood coating on the metal all over the car, primer caot it, and get it too say 2400 pounds.

[eturbo924]

To get some ideas on standard 924 modifications for more power got to my site and click link for 924 Power tricks. It is missing the supercharged 924 article, but to see a great supercharged 924 click on the link for modified 924s.

The 924S 1987-1988 ... don't know as much on that car, cam, air intake, header + free flow exhaust, throttle response cam, plus chip would be my suggestions. Of course for all that money you could purchase a 944S and get better brakes and chassis.

Eric
http://www.geocities.com/eturbo924

[AppleBit]

I did mine .040 over
safely .040 over is best.
.060 over is border line
.080 over is risky and recommended max


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