The Project Pad

So... if I were to buy a new turbo, AND I was planning on making a header, would there be any realistic reason why I should stick with the K26 hotside flanging?

The turbo I was planning on using is available with a .82 a/r K26 hotside (I believe this translates to a number 8) but then a small set of things turned up that made it very feasable to fabricate a turbo header, so I may as well just go that route. But at that point, why stick with the K26 flanging?

The only reason I can come up with is to make it easier to sell the turbo if I decide to change plans, or if I wanted to throw the turbo on my ported MC manifold to compare K26 vs. new turbo vs. new turbo on header.

T3 all the way. Or v band for the easiest swaps, just a little more $$. What turbo are you looking at?

I was thinking PT5858: http://www.precisionturbo.net/Street-an ... A-reg-/232

My ultimate goal is 500 crank HP on a 2.3l 10-valve. But that is somewhat of a lofty goal, and if I culd at least edge out what a Group 4 engine made, then I'd be thrilled. (It's kind of a mutant, not a "throw boost at a stock MC" engine) I was initially leaning towards the 55mm but from what I'd seen, the 58 has a lot more top end charge while sacrificing next to nothing on the low end. I don't particularly care about low end but broader is better if it costs nothing to do.

Now that I put my mind into the situation, the other K26s "pros" are that the exit is something small and not the 5-bolt T3 monstrosity, and I have never had good luck with V-bands on other cars. It seems that once things have heat cycled, nothing ever lines up properly again and then you are fighting large diameter stainless steel trying to moosh things together close enough to get the band started, and it ends up being a lot more of a pain. Cost, IMO, is not significantly different, once you pony up for the correct turbo-friendly studs and nuts. But, I guess, if there's a significant performance advantage one way or the other, then I'll go with what works more efficiently since this is still just the planning stage.

PTE5858 with .63 vband hotside without question. This hotside is proven to perform as well as the larger ones and gives much better spool. If not go T4 flange. T3 flanges suck ass and are difficult to keep fasteners tight.

The vbands will change your life

I work on Grand Nationals, never an issue, except for the ones with V-bands, then I start cursing

Really, a .63? I am not worried about spool. Ideally, the engine won't go into boost below 4000rpm. Heck, with the worn out JT, I don't ever find myself below 4000 and the engine is dead by 5200 or so. The engine I am putting together should sing to at least 7000-7500, in theory anyway. With the close and short 016 gearing, it should be like Dr Jeckyl and Mr. Hyde.

I guess the info I have gleaned from rotaries is showing itself... if this was a rotary then I'd be reaching for a 1.32 a/r divided housing Maybe they're weird, but increasing the hotside size has huge benefits with respect to reducing detonation, and uncorking the exhaust seems to make the engines spool *better*, if you can believe that. At any rate, I feel good about reducing exhaust restriction. The 20v needs all the help it can get as far as reducing detonation goes.

I guess I assumed it was a 20v. You will loose 5-600 rpm spool by going to the next size up, which will put you somewhere around 4600 rpms. For a 20v you are right, it's probably a good idea.

What you are talking about would be a good setup for a T4 divided housing and a quick spool valve. Highly recommended if you can spare the price of the valve from sound performance.

Why wouldn't you want a big fat torquey power band or anything below 4000?

My driving style in town is to drive at heavy throttle and upshift early as necessary to keep from accelerating quickly. I don't WANT the turbo to spool up and get in the way of that.

Besides, 70mph cruise is something like 4000rpm. Building boost below that is completely wasted. It's not like I would need the power in town, and you can always downshift but you can't upshift past top gear, you know?

I'll see what gives. The housings aren't super expensive, so I could swap later if I wanted to.