924Board.org

[peterld]

Oh, I feel your pain Mac.....or more to the point, the owner's pain. I sure hope he is reading this forum.
I had a similar situation many years ago. I had entrusted a supposedly reputable shop to build me a motor and fit to the car. On collection the owner attempted to start the car followed by a loud bang. The 'mechanic' had forgot to tighten the crankshaft pulley and the result was four bent valves. They subsequently repaired the damage, and I drove it home to run in the mechanicals.
The following weekend I achieved 2 laps of practice at a race meet before disaster struck. This time I disassembled the motor and discovered damage similar to yours. It transpired the shop had machined the crank to very early 924 specs and there was several mm of play on the thrust bearing allowing the crank to walk. Of course no one would take responsibility and ever since I do my own work.
It is possible to have the piston skirts ceramic coated, however that would only be applicable if there was light scuffing and they still remained in spec.
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80/81 932/8 ROW

[924RACR]

Oh, as far as the pistons - I see no good argument to trying to reuse them.
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[Mclaren924]

I appreciate all the replies as always gents.

Vaughn thank you for that info, I knew something was holding me up and I had a feeling it was the clutch fork lol. It's been 3-4 years since I did my 931's clutch so still trying to bat away all the cobwebs. I think we share the same opinion on the pistons, for a long term engine build that desires reliability, those pistons should not be reused. Unfortunately that probably means needing to source new forged oversized pistons, and the catch here is my customer is very much wanting this rebuild not to take half a year. From my understanding, it's probably going to be a few months wait to get a set from JE or Diamond or another similar manufacturer. If anyone can weigh in on that I would be very thankful.

Peter it definitely hurt me to see all this damage, customer has had this car 1 year and maybe put a couple hundred miles on it. Already paid 6k to other shops for a bunch of brake work and a list of odds and ends and now it needs basically a complete motor/turbo rework. There is roughly .100 crank walk laterally, going to reach out to customer to see if I can get in contact with the shop that built this motor along with the PO so I can at least get some more background on what's been done. This is a pretty fresh engine build, there was still assembly lube traces throughout the engine.

Going to shop now and will report back findings tonight.
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1980 931 "Salt" Bucket wannabe racer (Dreaming)
1979 924 Sebring "Pepper" -Sold
1977 924 Slicktop "Pennie"-Most likely parts
1979 3/5 gt clone 924- Shop Test Car

[Mclaren924]

Currently hunting everything down.

Planning for 88 mm 8.5-1 pistons through EBS or a French company called J2L.

Customer wants to convert to an EFI setup so currently getting some info from Morghen and more than likely going to pull the trigger on his kit today or tomorrow.

Headed to shop now to start going through the clutch pack/pressure plate setup and see if that caused our issue with crank walk.

Customer will is probably going to wind up having the transmission (G31) and torque tube reconditioned and a wavetrac LSD installed. I remember a thread on here of somebody talking about a shop that new what they were doing with doglegs over here in the states, going to track that down or try to lol. You guys have any recommendations for trans/torque tube work on a G31 setup here near the west coast?
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1980 931 "Salt" Bucket wannabe racer (Dreaming)
1979 924 Sebring "Pepper" -Sold
1977 924 Slicktop "Pennie"-Most likely parts
1979 3/5 gt clone 924- Shop Test Car

[Mclaren924]

[Cedric]

[Mclaren924]

Went on the hunt and found the alfa rod bolts as well as Pauter lightweight rods. Presented both options to the customer with the preface that in no way were the rods needed but would be a nice upgrade and would help with reliability. They wound up opting for the rods so they will come with ARP 2000 bolts and will take care of that issue. EBS is sourcing them at 4-6 weeks for $1150.

Going to have the RA specified to the machine shop so they deck the block and head correctly for the cometic gasket but that is a good reminder to make sure I specify it as it would be really shitty to have that cut wrong lol.

How much has been made before or is capable in theory, of being squeezed out of from a 944 hybrid turbo setup?

Last and most important question I have. Can anyone actually guarantee the fitment of a 915 diff into a g31? I'm 99% sure at this point as I just measured a G31 Diff I stripped down from a parts tranny, but would like some input from somebody actually running one. The Quaife tech specs even say it's for a 924 turbo/915/911 so I'm pretty confident at this point.

https://shop.quaife.co.uk/wp-content/uploads/2014/03/QDF1Q.pdf

Morghen is wrapping up the EFI kit to send over and the pistons and rods are getting forged as I type so got a lot of the gears moving on this project.
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1980 931 "Salt" Bucket wannabe racer (Dreaming)
1979 924 Sebring "Pepper" -Sold
1977 924 Slicktop "Pennie"-Most likely parts
1979 3/5 gt clone 924- Shop Test Car

[morghen]

EFI kit is on the way!
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Supercharger and EFI kits
https://www.the924.com

[Beartooth]

[Mclaren924]

Sorry for the long delay guys it has been crazy over here. So here is how the car currently sits



Customer has decided that he wants to go for a GTS style clone that is similar in form and function, will not be trying to replicate it exactly parts wise. That being said he is opting to run a GTS intake from mittlemotor and a front mount IC.

The trans is off with Jim Bennett in Santee CA to get the quaife installed, awesome guy who does a lot of VW and porsche transmissions and is a wealth of knowledge.



Beartooth you ask great questions, the pistons are ceramic coated and I opted to have the pistons made from 2618 for a couple of reasons. Ultimately it boiled down to this car being a pump gas aka 91 OCT setup, if this was going to run ethanol it's whole life I probably would have felt confident with a 4032 setup. This car is going to be shooting for 300-350 whp on ONLY pump gas so the extra ductility and fatigue resistance sold me. While it is a street car, it won't be getting driven tens of thousands of miles a year so for that reason I am not concerned about the potential premature or accelerated ware of 2618 compared to 4032. There's more to it than this but this was just my condensed reasoning for picking 2618l.

For ference about the Pauter rods, they are almost exact same price as pistons with ARP-2000 rod bolts.

I absolutely agree a better manifold and modern turbo is the way to go but that is a LARGE amount of custom fab work $$$ as well as a decent chunk of change in SS to make it all look nice and function well. Second issue is time, lotssss of time to make that work. While neither of those are reasons it shouldn't be done, my customer likes the idea of keeping stuff OEM or OEM++ so the upgraded 6ar housing with custom lancia turbine is a good fit for us. My customer wanted to go with a genuine GTS turbo setup but our supplier doesn't just have them laying around, go figure lol.

For what I'm doing now with the car, getting it ready for engine bay paint so having to clean up all the butchering the PO did to the engine bay, inner fender, and floors. The previous donkey self tapped screws to hold the 944 inner fenders in place and they put two through both sides of the footwells. Water got up in there and wrecked havoc on drivers side, passenger side isn't too bad. I also have to cut out this horrible radiator support the PO made and used silicone to seal up... Yes silicone on a "welded" up radiator support.





https://imgur.com/J4WBT8B

Final cherry on top was when I went to start disconnecting fuel lines from the bay, I had to pull all the top hard lines that run to filter, disconnect filter with a rag under and the blue rag starts turning orange. Uhhhh dafuq? I think to myself, proceed to go back to the tank and drain from the pump inlet and let's just say another issue has been found. The more and more I get into this car, the worse it gets



Ciprian/Morghens EFI kit showed up today, as a machinist myself I must say I am very impressed with the quality of the parts in the kit. It certainly wasn't free, but I think you'd wind up spending similar money if not more to make something as nice as well as have to deal with all the R&D which is not easy or cheap.



On a final side not, has anybody ever messed with the window scrapers? Holy #### toledo batman, nothing in recent memory has given me so much grief. I've spent 8+ hours trying to make it fit GOOD and it never sits flush on the door, you either get a floppy unhooked but good looking or its stiff and clipped in and looks like shit. Almost like the part doesn't fit. I confirmed PN but the new part is so much thicker and canted differently than the old part I took over, i seriously doubt I could ever get that seal to sit flush. Alright enough off topic ranting, just had to complain.

Will update more as more happens
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1980 931 "Salt" Bucket wannabe racer (Dreaming)
1979 924 Sebring "Pepper" -Sold
1977 924 Slicktop "Pennie"-Most likely parts
1979 3/5 gt clone 924- Shop Test Car

[924RACR]

I have indeed fought, unsuccessfully, with the window scrapers.
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[Cedric]

Haha, those window trim things, absolutely evil things!

That power target on 91 is challenging, and needs a right sized turbo. One alternative is a 944 compressor as i wrote above, same size as GTS but easier to find, and there are billet wheels available. One maybe better alternative for that power level is to just make an adapter plate to the manifold and fit up a more modern turbo. Shouldnt bee to hard for you.
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1980 924 Turbo
www.instagram.com/garagecedric/

[Cedric]

Crazy amount of tank dirt btw, that thing needs a complete clean out before any driving, glad you found it.
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1980 924 Turbo
www.instagram.com/garagecedric/

[Beartooth]

Dang, sounds like one of those jobs where you wish you could go back in time and help the PO do it right. And ounce of prevention is worth a pound of cure... I do wonder sometimes if I'm overthinking 2618 vs 4032. It's an easy answer if it's going to be run at the ragged edge - 2618 obviously. More on the other end, hypereutectic pistons might actually be the best choice; the question, if you definitely need something stronger than cast, is where is 4032 enough, and where do you need 2618? On the other hand, someone building an engine that truly needs 2618 pistons is probably going to break something else rather than simply wearing them out. I'm probably an outlier who'd drive his 931 as an economy car (almost 5000 miles on mine in less than two years and getting mid to upper-20 MPG despite a very tired engine), so hence the interest in the middle gorund. Anyway, I don't think there's any doubt 2618 is the right choice in this case.

I had a similar issue with rust in the gas tank: I pulled out a coffee cup worth out of mine a couple hundred miles after I got it going. I don't know what the best solution there is: I know you can get products to coat and seal an old gas tank, but I've also heard of that stuff delaminating and making a real mess. If I can get to the point where the rust stops coming back, I might just leave well enough alone... Good to hear the positive report on Morghen's EFI kit. He obviously put a lot of thought into it, so it would be silly to do all that legwork yourself unless you were pushing well beyond its capability. I hear you too on the turbo setup; while there's quite a bit you could gain, it's a massive undertaking unless you do that kind of thing for a living. I have some idea of how much fabrication it'd take just to cobble something together. It'd probably run over ten-thousand dollars worth of fab work to have it professionally done. I'd have to be making a lot more money to justify spending that much, and to do it personally would be way more undertaking than I'd probably consider - even if I could somehow be assured it'd come out right. Anyway, it looks like the car is moving in the right direction; keep us posted!
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1980 931 diamond in the rough

[Mclaren924]