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YOUR RESEARCHIt's Back - 3.7 Content *Now With Prelim Results*
Leading reported evidence
Install with arp fasteners
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Performed · outcome unconfirmed · Original poster
- Original rods crack tested and fitted with ARP fasteners.
Leading evidence: 'Install with arp fasteners' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'word i was looking' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Install with arp fasteners' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed · Original poster
- Every chain, guide and associated parts replaced with new Porsche supplied bits.
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Performed · outcome unconfirmed · Original poster
- Big ends and mains replaced with new Porsche supplied items.
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Performed · outcome unconfirmed · Original poster
It is afterall a road car used for lots of long journeys so needing to string it out to the last shift light all the time is tiring at best.
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Suggestion
LN put their companies reputation on their ceramic bearing some years ago but ended up denying all responsibility for the engines that failed due to the design so I'm not sure the roller is the tried and tested route yet?
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Suggestion · Original poster
If you do mean axial then the FAG TB type bearings have an axial load capacity of 60% of their radial load capacity so there is little point using a single row bearing for axial load handling reasons when you can do it with a roller bearing.
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911uk: 1 discussions
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Generation: 20261027T171335Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
So my old knacker came back on Friday, I was meant to go and get it about a week earlier than this but everything that could kick off has kicked off at work and I've been a bit snowed under!
At least it was a nice weekend for it!
I'm putting some gentle miles on it at the moment ready for heading to the dyno late next week to see what it will make. It has A LOT more low RPM torque than it ever did previously which is going to be due to the extra 300CC and valve seats that aren't half a million KMs old :lol:
From the original engine we kept the castings, crank, rods, inlets and exhaust manifolds and that's about it. Full list of everything that went into it as follows:
- Original 3.4L block/crankcase machined by Capricorn to carry 100mm bore liners converting it to a closed deck design with additional machining work to provide additional coolant flow around the liner tops.
- CP 100mm 3 ring forged pistons with reduced skirts to minimise frictional losses.
- Original 3.4L heads rebuilt and mildly fettled with new valve seats, single piece valves, new Porsche lifters, springs, retainers etc. new standard spec cams.
- Every chain, guide and associated parts replaced with new Porsche supplied bits.
- Big ends and mains replaced with new Porsche supplied items.
- IMS bearing converted to pressure fed roller bearing - best option given the OE dual row is NLA.
- Original rods crack tested and fitted with ARP fasteners.
- Every gasket and o-ring seal (no matter how small) replaced with new Porsche supplied bits.
- Twin chamber Porsche "Motorsport" Air oil seperator fitted in place of standard item.
- All fasteners replaced with new.
- All belt rollers, tensioners etc. replaced with new.
Oil system and cooling system carried over from the old engine as these clearly worked very well indeed along with the GT3 throttle body, low loss intake and equal length exhausts. Given the heads now flow a bit better and the valves are less shrouded from the larger bore, it has another 300CC and less frictionals I'm hoping it will make similar power to a Mk1 GT3. We'll find out next week :lol:
My main aims with this motor were to make a better road car version of the M96, considering the mileage it had managed there wasn't a lot to do reliability wise but I did want to find some more performance without compromising its road manners, going larger bore and doing this with capacity rather than cams etc. is really the only way to do this as I really didn't want to end up with a peaky engine that needed revs to make good torque. It is afterall a road car used for lots of long journeys so needing to string it out to the last shift light all the time is tiring at best. I also really didn't want to go up in stroke (hence not using the 3.6 crank to make a 3.9) as in my experience those engines with the lowest mean pistons speeds generally live the longest. With a 78mm stroke and a 7250RPM limiter the worst case mean piston speed is still only 18.85MPS which is pretty low all things considered and should lead to a happy and long lived engine
I think that is about it now for modifications aside from building a display into where the rev counter currently lives I have no more plans for the car aside from pile the next 300K miles onto it as quickly as possible.
It is so nice to have the old girl back on the road
Yes no surprises or dramas. Autofarm were great to deal with, as they always have been in my experience. I think we were a bit under budget in the end.
What made you decide to go with a roller bearing, I would have gone with a single row and spaced it due to lateral movement if the dual row wasn't available?
Looking forward to the hp figures with a 3.7.
It will be interesting to see your dyno results and general improvement with this upgrade, I`ve been thinking of doing the same thing :thumb:
What were the costs involved if you don`t mind disclosing, via PM if necessary :thumb:
Do you mean axial movement? If you do mean axial then the FAG TB type bearings have an axial load capacity of 60% of their radial load capacity so there is little point using a single row bearing for axial load handling reasons when you can do it with a roller bearing. We've used the same bearing design in F1 gearboxes where they have very high transient axial loads with great success. Plus as a company has put their money where their mouth is and paid to have a specific TB type bearing made to do this job it seemed rude not to give it a go, what's the worst that can happen :lol:
Axial is probably the word I was looking for, although I'm not a mechanical engineer, I do hope that roller bearing solution works out.
Gearboxes are quite tight in their axial movement compared to the IMS design on a 996 which almost floats in comparison. LN put their companies reputation on their ceramic bearing some years ago but ended up denying all responsibility for the engines that failed due to the design so I'm not sure the roller is the tried and tested route yet?
Road car gearboxes are.... a 2K onwards F1 box with a gearbox mounted clutch and first and second motion shafts that are essentially fully floating in the bearings at certain points in the gear change is something quite different
Sounds just about the perfect solution ppbb :thumb:
Knowing you I'm sure you managed to do the running in miles within an afternoon :grin:
Look forward to hearing how the performance compares once you have the chance to really open her up
