Endurance racing engine choice for power and reliability

[buzzboy]

I have been into crapcan racing for the past 8 years. My team Idle Clatter Racing only races diesels. We like the torque, fuel economy and reliability of diesels. Up until now we've raced diesel Mercedes. However we're looking into going to a smaller and lighter car. I'm also intrigued by the availability of performance parts in the US versus MB performance which is mostly only in Europe. A friend of ours has a 911 racecar with an ALH swap that he raves about which pointed us to TDIs as a step forward from our OMs.

Goal would be in the neighborhood of 150whp without completely throwing budget out the window. From a cost of car perspective I'm looking at an ALH, BEW or BHW. Looks like a BRM is going to cost more initially and have some reliability issues possibly between cam and BSM so that's off the table. I wanted confirmation of the research I've done and maybe input into which direction I should go.

ALH
Weaker bottom end
Lower stock power potential
No cam issues
No BSM

BEW
Stronger bottom end
Higher stock power potential
Potential cam replacement
No BSM

BHW
Stronger bottom end
Highest stock power potential
Potential cam replacement
BSM delete required

The ALH doesn't need any parts replaced for reliability but needs more parts for higher power. Even then, would upping the power to where I want decrease reliability in endurance racing?

The BEW might need a cam replacement and mild upgrades to hit my power goal.

The BHW
The least stressed engine to hit my power goal but the most reliability issues that need to be resolved before racing.

It seems to me that the BEW is the sweetspot that I'm looking for? The goldilocks engine. But I don't completely know and would love to get input from other TDIers before I start trying to buy a car. I've been checking cars out on all the usual sources and I've found a bunch that I like. Just need to pick which engine I want before I go buy the car that encases it.

 

[IndigoBlueWagon]

ALH with 11mm pump, VNT-17, PP520 injectors, and a good tune (Rocketchip Stage 5 is my recommendation), along with a 2.5" exhaust and PD150 intake manifold and airbox/intake, will get you in the 150 HP range with manageable EGTs and no engine internal work required. I ran a similar setup on track days in my Wagon and it was both fun and dead reliable. ALH will rev better than a BEW: I had a 6,000 RPM tune which was a bit extreme, but 5000-5500 is easy to reach. And these engines just go and go. Probably cheaper to buy and build, too.

Second place vote would be a BEW with the same turbo and a Stage 3 or 4 tune, stock fueling. That will get you similar power.

 

[Mozambiquer]

The BHW will hit 150 whp with merely a tune. If you look on car-part.com you can pick one up for less than 1k. Get a franko6 cam and balance shaft delete kit, tune it and you can be up over your goals without having to touch the engine internals.

 

[Poor King]

ARL!

 

[oilhammer]

The BHW will surpass 150hp with just a minor tune. And if properly cared for, should hold up just fine. PD cams are not nearly that big of an issue as you may be led to believe. All mine have 200k or more, some of my regulars have over 300k, etc.

 

[Mozambiquer]

All of my BHWs have over 200k miles. Two of them are on their original camshaft, the other one has a bad Colt cam (a manufacturer flaw in the batch of cams) that batch was what propelled franko6 to start making his own cams. The BSM delete isn't really that hard, especially since you're probably not going to using the B5 chassis, but instead something else and thus could probably use the alh oil pan instead and then not even need the 1.8t pickup tube and etc.

 

[buzzboy]

Thanks for the thoughts guys. Think I'm going to be looking for a BHW. Probably going for the whole car for parts and maybe to recoup some cost.

When a cam goes out in a PD engine what are the symptoms? If it just starts running worse or stops running that's cool, I'd just like to be sure it doesn't grenade the engine by sending metal flakes through everything.

 

[oilhammer]

The end result is typically a miss, because the hydraulic lash adjuster wears through and can no longer hold oil pressure, which just pushes right out the hole. But it is a more gradual loss of valve lift over a long period of time.

But this is not any reason to avoid one, as many can live good long lives, even if the camshaft and lifters in them can be tagged as a "wear item" more so than the VE diesels before them.

A brief history of VAG (Audi) SOHC engines:

They were born with SOLID lifters, a simple flat tappet cam-on-bucket design many OHC engines use (even still today). They used shims atop the lifters to set valve lash, the shims being available in a wide variety of thicknesses, and easily checked and swapped if necessary, although most of the solid lifter engines never got any valve lash checks (and often never really needed any) during the life of the car.

Starting in the early '80s, the inline 5 and 6 cylinder gasoline engines started getting a hydraulic lash adjusting lifter installed. I think we would have seen in first in the Audi 5000 around '83 or so. By the middle of the 1986 model year, the 4 cyl engines... both gas AND diesel, got them. Not sure on the 5 and 6, but the 4 cyl hydraulic lifter engines got a couple modifications that coincide with this change: a bigger, higher volume oil pump, a bigger oil feed port to the head, bigger oil galleries in both the head and block, and an extra oil return port between the head and block.

But they remained a direct flat tappet design, the cam lobes operating directly on the lifter, metal on metal. Which is not "ideal" for hydraulic lash adjusters that essentially maintain zero lash (no "clearance" between the cam lobe and lifter). And the critical period, at cold start, it is made worse since the oil pressure is higher due to oil viscosity. Whereas the solid lifter cars, when cold, literally had a [comparatively] giant GAP (lash) between the lobes and the lifters during this start up period. So oil is easily able to get in there, even thick cold oil.

Solid lifter engines never, ever, wore out cams or lifters. I've been wrenching on these things since I was a kid, I have never seen a single one, ever. Even those that were trashed, abused, run low or OUT of oil... the camshafts still were fine.

The general size and shape and robustness of the basic design, however, tolerated that less-than-ideal change to hydraulics starting in mid-'86 OK, though, and with rare exception, these hold up perfectly fine. The only issue I have seen is on higher mileage (and I am talking 300k+ miles or more), the lifter bore in the head can wear and the lifter itself fits loosely in the head and is unable to seal the oil pressure being fed into the little hydraulic lifter hole. This can result in some lifter bleed down, usually just at a hot idle (and sometimes only after idling for a minute or more), and generally of no concern. I have seen a few early TDIs (which are still based on that old Audi design from 1974) get so bad that the lifters cannot ever pump up completely, and the engine just ticks all the time and slowly pounds the lifter and makes a little bowtie pattern on the top (if the lifter cannot pump up, it cannot rotate properly). In those extreme cases, the only fix is a new head, or boring and resleeving the lifter hole. In any event, those engines will still run fine and continue to move the car (I had one of those).

The PD engine changed things. They decided to run unit injectors off of the camshaft directly. Each cylinder's injector is driven (via a roller rocker) off of its own dedicated cam lobe. In order to fit these extra four lobes to the same length camshaft, they had to make the lobes that work the engine's valves narrower, by about 30% or so. THAT is what causes the increased wear more than anything else. One strike: flat tappet cams (no fancy roller rockers or anything, direct metal-on-metal valve actuation). Two strikes: hydraulic lash adjusters (no clearance, strong push against metal-on-metal parts 100% of the time). The PD cam was Strike three.

Now I know VAG must've known there was a weakness here. Because they did not only grace the head with replaceable camshaft bearing shells (something none of the previous engines had, nor to most any OHC engine.... they just ride the cam directly on the aluminum head), but they came out with an even more stringent oil spec (this has been debated here many times). They also seem to have placed the oil feeds to the camshaft itself in a spot that might not have been ideal.

Our friend Frank Irving has identified some of these shortcomings, and has some modifications he claims that helps with this. While I do not agree nor disagree with his findings and modifications (I have no experience with them) I do feel that most PD engines can, just as they left the factory, live a decent life that is often beyond (mileage wise) what most people (even many new TDI purchasers) would have expected the car to remain in their driveway anyway.

But, like prostate cancer, if you live long enough, the chances of it becoming a problem approach 100%. I still would not let this steer me away from a PD engine, and many of us simply don't worry about it at all. If my PD needs a new cam and lifters after 300,000 miles, so be it (it probably won't, but...)

 

[mozark]

Great post

A brief history of VAG (Audi) SOHC engines: .............................

 

[buzzboy]

I bought a Passat with a 160k and some issues. Donor drives really well.

Any trick to pulling this engine? I tried pulling the engine and leaving the trans but I can't get to the bellhousing bolts. Started trying to drop the subframe but I can't get the strut mount bolts out all the way as they contact the lower control arm. So is the trick to pull engine/trans and leave the subframe?