Carpokes

If all that was damaged due to low oil pressure were the crank and rods then I'd source a good used crank and carrillo rods. I can't help thinking that trying to go "too big" with these engines multiplies the risk of failure. I think 3L and the associated long stroke is already borderline for a race engine. There you have the opportunity to move down to 2.7L with a 951 crank which may not be as difficult to source and as expensive as an S2 or 968 crank, and your engine will rev all day long reliably and make the best of the massive top end spec, perhaps with less torque overall but do you really care about peak figures at this stage when you simply want to have a running car... Hang in there I say.

That's a very interesting thought Thom. Seems a little odd on face value to toss .5 of a litre away but I hadn't considered that. I was looking at sourcing a brand new 3lt crank from the factory. The loss of torque would ordinarily concern me but the points you raise are valid. Thanks.

It's too early to draw the curtains. At least not like that. Yes those cars are absolutely draining and I can only begin to grasp your frustration but look at all those high end parts you have thrown at it. Don't think you need a new crank. Lots of high end builds out there with stock cranks. Less torque means more reliability. That the clutch was slipping at only 13 psi of boost suggests to me there was too much torque. It couldn't have fared well, or at least for not very long.

Well that clutch did hold more tq in the old 3.1 lt 8v motor. Never had any slip. Same with 25psi in that other 2.6lt 8v. Don't know why it was slipping at less power/tq this time. Perhaps some fire retardant got in there too? Will have to open it up and see what it looks like.

Sorry, I meant that the engine would not have lasted long if it made that much torque at such a low boost already. This brings another question on what sort of longevity one may reasonably expect from such a highly-tuned engine. Without the oil pressure issue, how long do you think it would have lasted? I know this is a how-long-is-a-piece-of-string question but whenever I hear race engine I foresee the high running costs such as opening it up regularly which adds up to the yearly bill even if every bit checks out fine. Look at how many times Duke had everything apart even when his Porsche engines were running sort of fine. I don't mean to discourage you in any way, but just want to stress how happier you'd be with a car that just runs with perhaps a slightly less stressed engine like a 2.7 not making more than let's 400 lbs.ft but a healthy 550 hp at the crank at no more than 20 psi of boost. Considering how my street car goes already I'm pretty sure that even my humble engine would move your much lighter car more than fast enough.

All good points Thom. I'm giving it some thought. Just getting it back together seems a little way away. Dealing with other financial strains elsewhere. As for reliability and pull downs, well in reality the car would do very few laps and the hours on the engine are drawn out over a season. A 992 Cup car would definitely require rebuild/refresh each season as they do many hours per year. My car would do a tenth or less of what a 'real racecar' does.

There has to be a light at the end of the tunnel that isn't a train coming the other way. I prefer to offer further options, for what they're worth, rather than shake my head in despair. Advice is cheap, obviously.

Definitely appreciate your input. Increase boost, decrease torque. Somethings to consider.

I would consider torque the main data to keep in check. Boost will just be what it will be so that your turbo can support the flow requirements of the top end. Once you get a feel of where the engine feels healthy with a certain amount of torque and how the curves look like it is always possible to fine tune the torque delivery and overall response by adjusting turbo boost level then, if it's not satisfying, turbo size. In my limited understanding and experience at least. Your turbo seems properly sized already. Clearly I wouldn't shop for a new one until the next engine is already running and assessed on the dyno. Messing with different variables at the same time never helps with understanding a particular engine, unless you're the Albert Einstein of all engines which I'm not.

Yes, I was going to mention the turbo. Dropping half a litre in capacity gave me pause to think about what is there now. Having said that, the tuner on the dyno remarked how well it was spooling and we could potentially go up in size. So to your point, if we went for 2.7lt I'd stick with the setup we have before looking for an alternative.