OriginalSterm

i should head across town to swain to have some of my exhaust components coated. geo has recommended this to me in the past, as well as other's on the board. didn't know they did internal engine components as well.

macnewma

I had no idea they were in Rochester. That is perfect for you. IMO, if you plan to keep the car for an extended time and you want to track the car, you should definitely coat your exhaust components. Heat is an engine's worst enemy and turbo track cars suffer from it worse than most. I imagine I will spend between $500-600 to get my stuff coated and that will be well worth it.

Max

Mike S

I've got the HPC coatings on my rod bearings and HPC's coating on the pistons. It's only been about 5-6k since the rebuild but so far everything is holding up well.

sm

Did you notice a difference in engine smoothness as a result of this?

jda407

All great advice and much appreciated. I too have gotten a new block. Because there was way too much crap that went flyin' around when the #2 went. So I've gotten a new block and am looking to make it more "bulletproof". This is for a track car yet I'm not that concerned with more horsepower at this point in time (hell...right now I just want the engine back in the car and the car back on the track) I'm not sure that I will do the crossdrilling, however a great idea, but I'm not sure of someone local that can do it in a timely manner. Correct me if I'm wrong...and slap me into reality. Head has been sent out for a "clean up" and for the valves to be corrected. I'm definitely going to do rings and bearings. I've actually gotten mixed feedback on rods. I've gotten a lot of feedback that says the rods in the '86 engine are the best to have. So I'll probably just check all of them and leave them be. Outside of that, it looks like bolt off and bolt on from my old to new block.
All the input is much appreciated and I will continue to be a sponge for all the knowledge kicking around this group of people.
thanks

420bhp944

I suspect the same thing happened with my car at a track day last week,It went when I was going through a series of tight bends at relative high speed, heard a metallic rattle and lost power...I will know exactly the extent of the damage when the engine is pulled and inspected. That oil pan baffle kit sounds like a good mod regardless of what happened, looks like the no.2 main/rod bearing is a weak link then?

Danno

Note that the Huntley procedure is a perp-drill, not a cross drill. You drill a 2nd hole at 90-degrees to the 1st one so that the hole is at the outermost swing on the journals. Then the centripedal force of the crank-spinning forces the oil out. Every single high-revving engine, like 15,000rpm motorcycle engines, have had the oil-hole on the outermost part of the journal, not sure why Porsche put theirs on the side...

macnewma

Danno, your drawing depicts the perp-drill, right? What exactly is the cross-drill relative to the perp-drill?

Max

RMills944

cross-drilling I believe puts the original hole all the way through the crank. (180 degrees from the original)

RMills944

Here's a pic of a huntley race-prepped (knife edged, drilled, and balanced)crank I found:

Close up:

Danno

Yup, the picture shows a "perp-drill" with a 2nd hold perpendicular (90-degrees) to the original one. No worries about reduced pressure because it's the bearing-clearances that's the flow-limitation; as bearings wear out and generate increased clearances, oil-pressure goes down. It doesn't matter how many holes you have in the journal, you're not going to increase oil-pressure or oil-flow because the exit restriction (bearing-clearance) is the same.... except...

The difference between a perp-drill and cross-drill is that only the perp-drill will place the the hole in such a way that oil-flow and pressure will be enhanced by the centripedal force generated by crank-rotation. Maybe we can rent some FEA time at NASA or some such place to model the extra pressure and flow. But I think having seen the hole placed on the outside on all high-revving motors would confirm that this is the optimum location.

I still suspect that Laust's assertion is correct, that there's some internal flow-restriction in the crank. If it was external to the crank, due to all the journals being fed in parallel, all the journals would be equally susceptible to an external source, like the oil-pump.

macnewma

Danno-

That makes sense, so why do people offer cross-drill and I don't know of anyone offering perp-drill? Am I just not looking in the right spots?

Max

Danno

Well, cross-driling has been around longer than the perp-drill. It's standard in hot-rodding V8 applications where low-pressure and low-volume oil-pumps are a hindrance to high-rev engines. In that case, a cross-drilled crank DOES provide a benefit because of the increased flow volume. But note in these applications, the original hole was already placed on the outermose circumference of the rod-journal rotation. The 2nd hole on the inside, opposite the flow, actually provided the extra necessary flow-volume.

In a higher-pressure. higher-volume application such as our cars, we actually don't need extra volume, so much as extra pressure. Due to the placement of the hole, it appears that it's aimed up at the highest-pressure area of the con-rod on the compression-stroke. The rod actually pushes down on the hole in the journal when maximum-combustion takes place at 20-30 degrees ATDC. This pressure from combustion may actually decrease bearing-clearance right at that hole, thus hindering flow.

So having extra pressure may help, but that requires a new oil-pressure relief-valve. Another solution is toplace another hole somewhere other than the highest pressure spot under the con-rod, and a cross-drill could help as it's on the bottom side of the con-rod away from the pressure. But the cross drill doesn't take advantage of the crank-rotation's centripedal force squeeze the oil out of the journal. So the perp-drill accomplishes two functions. First it provides a 2nd hole in a lower-pressure area of the journal and it enhances oil-pressure with the spinning centripedal force of the crank.

I do remember hearing that cross-drill doesn't help very much, but I'm not sure of the source. Could be Huntley marketing lingo. Personally, I'd go with the perp-drill.

cruise98

FWIW, I had mine cross drilled before I had ever heard of perp drilling. Before doing it, I had wondered why the oil hole was on the side of the journal, but hey, it's a Porsche right? I will perp drill the next one I do.