Silber’s 2002 Boxster S Engine Build

[Silber]

In the light of day my camshaft idea seem a little extravagant, probably just going to go with new lifters and my current cams.

Got the 4 to 6 case half taken off, going to lift out the crankshaft cradle tomorrow. LN Thursday. Confirmed the part number On my new crank box matches the part number on my current one, seller is shipping tomorrow.

Hopefully my ramblings are helpful, I’m going to try to post less frequent updates with more substance So as not to clog up the board with my rantings.

Silber

[Quadcammer]

Originally Posted by Silber

In the light of day my camshaft idea seem a little extravagant, probably just going to go with new lifters and my current cams.

Got the 4 to 6 case half taken off, going to lift out the crankshaft cradle tomorrow. LN Thursday. Confirmed the part number On my new crank box matches the part number on my current one, seller is shipping tomorrow.

Hopefully my ramblings are helpful, I’m going to try to post less frequent updates with more substance So as not to clog up the board with my rantings.

Silber

I seem to recall that the crank carrier and crank are matched to some extent. I'm guessing you would need to measure the bearing clearance and consider an align hone

[Silber]

Originally Posted by Quadcammer

I seem to recall that the crank carrier and crank are matched to some extent. I'm guessing you would need to measure the bearing clearance and consider an align hone

Just thinking about it, main bearings are a standard size. They have to fit the crank on the inside, and the carrier on the outside within thousandths of an inch. If there was much wiggle room there the whole system would fail, so my expectation is I’ll be fine.

That being said, My plan is to:
- check the crank for runout with a dial gauge in old carrier
- Measure main bearing clearances in old carrier with plastigauge
- check rod tolerances of old rods with plastigauge
- Check crank endplay in old carrier with dial gauge
- have crank magnafluxed
- check main tolerances with new bearings in new carrier with plastigauge
- check rod tolerances of new rods with plastigauge
- check crank endplay in new carrier with dial gauge

If I pass all those tests I think I will be OK, if any of the tests fail then I will have to figure out why and get back to the drawing board.

Does anyone happen to know the main bearing and rod bearing tolerances offhand?

EDIT: apparently rod and main measurements on these engines is a big secret, added steps to measure what I have first. My crank carrier damage is out by the cylinder, and relatively minor, so the measurements at the journals should still be good.

Silber

[Gilles]

Originally Posted by Silber

That being said, My plan is to:
- Measure main bearing clearances in old carrier with plastigauge
- check rod tolerances of old rods with plastigauge
- check main tolerances with new bearings in new carrier with plastigauge
- check rod tolerances of new rods with plastigauge

Silber, I am not a professional engine builder by any means.. but to build a performance engine that will last a long time, I would suggest sending the parts that you want to measure to a professional engine builder (or a specialized engine machine shop) that use precision measuring tools that will give you 100% accurate readings, I strongly believe that the cost would be cheap compared with a no so good build due to questionable measurements.

Please don't take me wrong I have used plastigauge in the past on a few engine builds (air cooled VW's, Alfas, Chevys, etc.,) and I feel that got lucky perhaps because the tolerances on those applications were not as critical) but after attending the Flat6innovations M96/97 engine building class, IMHO would not do it on a Porsche engine with very tight tolerances..
.

[Silber]

Originally Posted by Gilles

Silber, I am not a professional engine builder by any means.. but to build a performance engine that will last a long time, I would suggest sending the parts that you want to measure to a professional engine builder (or a specialized engine machine shop) that use precision measuring tools that will give you 100% accurate readings, I strongly believe that the cost would be cheap compared with a no so good build due to questionable measurements.

Please don't take me wrong I have used plastigauge in the past on a few engine builds (air cooled VW's, Alfas, Chevys, etc.,) and I feel that got lucky perhaps because the tolerances on those applications were not as critical) but after attending the Flat6innovations M96/97 engine building class, IMHO would not do it on a Porsche engine with very tight tolerances..
.

You bring up some good points. Thanks for taking the time to reply. Probably my best plan is to measure both ways, Plastigage and traditional measuring tools. I will have to buy a bore gauge and Mics, but those can be had somewhat reasonably nowadays. Always better to check and doublecheck, I don't want any surprises when I turn the key.

I am taking my crank to a specialist to get Magnafluxed, found a great shop about an hour out of the city. I will have them measure as well as do so myself. If I have any doubts about my measurements of the bearing carrier, I'll find someone to double check my work. There are a couple Porsche shops in town that might be willing to do that if I asked nice and paid for the service.

Silber