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Im trying to decide between a 6266 and a 6466.
Im stock stroke.
Forged bottom end.
Walton manifold with 50mm gate.
Light port work (stock valves).
Likely tomei poncam tybe b's with ajustable pulleys.

My ideal target is 600 hub bhp but will always choose a more responsive / driveable car at the expense of figures if needs be...

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On the dyno we were seeing 1bar between 4250 and 4500. Above that it comes in hard. On the road it varies and you rarely see 1bar under 5000.

On track it is a total monster, too fast to use WOT on boost for more than a second or two on the road.

There's some video with data overlay on my youtube channel from 2019 that gives you a feel of how it responds. On track i run 1.2bar mostly, plenty fast for trackdays. The engine makes a lot of heat at 1.5bar and that limits the length of runs you can do.

I'm considering a 4" exhaust and downpipe which should help lower the boost threshold and make less heat. Better placed oil cooler would help.
 

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Sounds like a handful! Well I’m hoping to be able to achieve similar spool up on my 2.6. I’ve got poncam type B also with a ported head. What exhaust have you got at the moment? Have you got your screamer going back into your exhaust? What manifold did you go for too?! (only reason I ask is mine failed noise test)
loads of questions Alex, but I’m collecting bits!!
 

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Its a hks silent hipower, been on for years. The manifold is APW , wouldn't specifically recommend it though, just what it was supplied - i wanted a 6 boost. The wastegate is plumbed back in to the end of the down pipe. The down pipe is 3" and is probably a bit small but again that's what I has supplied.

You might help the reduce the boost threshold with a type A exhaust cam.

I have seen plots of 6266 on 2.6s coming on 500rpm sooner than mine but even after a lot of dyno time and a bunch of experiments we couldn't reproduce that low a boost threshold.

Once you are above the boost threshold rpm (which is all the time on track) the actual "response" from closed throttle to full boost is great, only a fraction slower than my old GTSS turbos tbh.
 

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Yes we tried to swing the cams but that was as low in the rpm we could make the power. That's why I think the Type A shorter duration cam might be a plan.

I was looking for something that would make 600 @ flywheel fairly easily without too much boost. So 6266, 8374, GTX3582 etc. The 6266 making 550 at the rear hubs on "low boost" is spot on. The 6466 seems to make more power for the same boost with only a little higher boost threshold.

The exact turbo I have is part no 21104210239 - 6266 SP CEA-2 BB-1 W/ TH84D-66 which is a Generation 2 6266 with a T4 divided .84 A/R turbine housing.
 

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Yeah! 1 bar at 3500 is a really good Spool! (It is cold and night granted) It’s responsive, but does feel like it flattens out about 6500-7k. Infact, it makes the 605 at near 8 so does climb but not as quick. I think il be ok with a 3inch downpipe on my 2620cc engine. I might see if it’s not stupid load with the screamer external first off.
It’s good that your active on here still BTW! 👍
 

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My 6266 makes 450 at the rear hubs @1.5bar @4500 (350 @1.2bar) and peaks at 6800 and noses over gently after that, might be higher if we swung that cams the other way. That means you have 3000rpm to work with (4500-7500) so you can keep it on boost through the gears but you need to be committed to do that on the road. It's totally drivable under 4500 but not fast. Driving it through the transition from 4000-4500 on the road can be a a bit alarming.
 

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I may come back and ask more questions at some point Alex!
Sure thing :) I spent ages sweating over the SAU turbo upgrades thread trying to get data on the best setup, so I know the anguish of turbo choice!

Found the dyno plot I put up on SAU

Your APEXIs sound like a really good balance tbh. Power figures depend on the dyno of course (mine are all Abbey's dynapack), but it sounds like maybe the 6266 might not be that big a step up, if you want a bigger step up in power maybe the 6466 would be better or the GTX3584 which is a beast with decent response.
 
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