bazhart

NOT SO FRAGILE THEN!

We here so much about engine failures that I thought some good results might cheer owners up.

When we started racing the Boxster’s and 996’s 7 years ago everyone (including us) struggled with reliability over a full racing season.

Although we had rebuilt hundreds of road engines with 100% reliability – it took a lot of development to get the same engines racing round a circuit reliably.

This season in the UK’s top 3 Production based Porsche Championships our engines (built the previous winter) won all three Championships with a 100% reliability record – demonstrating that the small and subtle changes we make (combined with our rebuild skills) are worthwhile.

We also ran a podium based rewards scheme that has resulted in all 3 Champions earning labour free winter engine rebuilds – putting over £8000 back into the Sport.

Next season the Porsche Club Championship introduces the 3.8 engines and we expect this to follow the same set of challenges and a learning curve as the previous models.

Strictly controlled to standard road based internals (with a few minor allowances) this shows that progress has been made and that rebuilds to the right specification can create a very reliable engine.

Porsche Club GB class 1 Champion Mark McAleer 8 wins, 2 * 2nd , 1 * 3rd 100% reliability.

Porsche Club GB class 2 Champion Jake McAleer 9 wins, 2 * 2nd 100% reliability.

Porsche Club GB TEAM AWARD RVR 17 wins, 4 * 2nd 1 * 3nd 100% reliability.

BRSCC Boxster class 1 Champion Ed Hayes 15 wins, 4 * 2nd , 3 * 3rd 100% reliability.

Baz (Barry Hart, Technical Director, Hartech Automotive www.hartech.org)

dr914

so what were the main failures? Was the IMS bearing really as bad a failure rate as has been hyped? You would certainly be one of the best to have an opinion

mikefocke

And what pray tell would racing have to do with the life of an IMS bearing in normal road use? Completely different conditions.

bazhart

Well Boxster 3.2's are not so fragile as the 3.4 and larger engine versions.

Most had ferrous coated pistons and much thicker cylinder walls (they bored out the block to increase bores by 3mm for the 3.4's but didn't increase the outer cylinder casting diameter).

The cylinder centres and the overall block height remained the same from 2,.5 right up to 3.8 - gradually creating smaller coolant space etc.

For racing a new IMS standard bearing will last between engine rebuilds anyway although we do manufacture a modified IMS shaft (both roller chain and hivo chain alternatives) with the larger later IMS bearing - that with seal removed is as reliable as it can be.

The main problem racing is the wear on the main bearing shells caused by crankshaft flexure changing down rapidly and starving the big ends and heat soak after a race during the cooling down period.

Baz

Opposer

So if I plan to circuit rarely (10-12 15min sessions a year) I can take 3.2 986 without worries of bore scoring and oil shortage like 987 3.4 has?

Macster

Whether you enage in one 15 minute track session or 100 all it takes is a moment of insufficient oil to ruin the engine.

My advice would be if you want to track your Boxster S install a good quality deeper oil sump and baffling system to help ensure the oil the pump pulls in is as free of air as it can be. Show up at every track event with fresh oil in the engine.

At the end of a 15 minute session take a cool down lap then once off the track let the engine idle for a few minutes to shed the heat load the engine/cooling system have.

Not sure what you can do about "bore scoring". Some of the causes and recommendations to "prevent" bore scoring put forth read like nonsense to me.

I think about all I can offer is just treat the engine with a reasonable degree of mechanical empathy. Run an approved oil. Be sure the viscosity is appropriate for the ambient temperatures where you live and drive. Mainly this means if you drive the car in cold weather run a 0w-40 oil. Do not run the oil too long. I follow a 5K mile oil change schedule with both my Boxster and my Turbo and the Boxster engine has covered over 315K miles and the Turbo engine over 160K miles with no engine problems.

After a cold start I like to let the engine idle a while -- my "timer" is the secondary air injection pump, when it shuts off that's when I then head out -- to gain some heat. The engine won't be anywhere near up to full operating temperature so you still have to watch RPMs. I keep RPMs below 4K until the engine coolant temperature (Boxster) has been at the "180" hash mark for some minutes. (I have data logged coolant temperature of both my Boxster and my Turbo and it can take 10 minutes or more of running before the coolant is up to "temperature".) Oil temperature lags coolant temperature so some more run time after the coolant is up to temperature is called for. For the Turbo I use the oil pressure gauge. When the hot idle oil pressure is at 2 bar I know the engine is up to temperature.

After hard running continue to let the engine run, at idle, a while to give the engine and its cooling system time to remove the heat load the engine has. A hard running engine can have its exhaust valves heated to nearly a red heat. The valves are mainly cooled by contact with the valve seats. At idle the valves spend the most time closed and combustion temperatures are at their lowest.

Perform services on the car at the proper miles or time. This includes engine air filter (and don't forget the cabin air filter), spark plugs, brake/clutch fluid flush/bleed, transmission/diff fluid change. Keep the radiator ducts free of trash. Keep the body water drains free of trash. After the car is exposed to water -- rain or wash -- check the door bottoms for signs of dampness. Dampness in this area is a sign the door membranes are leaking and letting water from the wet side over into the dry side.