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Turbo cam grinds (for my isuzu triple-cam...)

Posted: 30 Apr 2008, 01:45
by archangel62
I'm looking at getting cams made (from scratch...) for my G180W. It'll be using a Garrett GT28RS turbo, with the smaller exhaust housing. This is a very responsive turbo, and I'll be tuning for response throughout the rev range, aiming to hit boost below 3000rpm if possible, and make power right up to 7000rpm+. I'd like 200rwkw, but I'll be happy with 150 if it's responsive.

What sort of cam grinds should I get? I want it to be very driveable, but EFI should help that. As I say, aiming for response over power. For those who have a minute, read on, and find out what inspired me to get the cams now...

GOOD NEWS:
The head is FINALLY on my twincam.

BAD NEWS:
When I was tightening the nuts on the cam bearings, I was a little surprised to find that the exhaust cam wasn't too keen on lining up. "No matter," I say, "it's just the valve springs resisting."
So I keep tightning the cam bearings to pull the cam down... Most of them still had like 5mm space between the bearing halves.
CRACK.
Everyone stops.
"Damn, must have stripped a thread or something."
"...Uhh... F***..."
At this point I discover the exhaust cam has actually snapped, through its centre, and is in two pieces. Now I don't know what the hell happened, but looking on the bright side, I'm glad it happened on assembly, not at 7000rpm. The weird thing is, all valve buckets had been rebuilt professionally and didn't provide any more resistance than they should have been. All the cam bearings were lining up alright (and are fine thankfully). The only thing I can think of is that the timing chain tensioner wasn't giving enough slack or had jammed for some reason.

Heh... But yes, any help appreciated :D

Posted: 30 Apr 2008, 03:50
by IZU069
Curious breakage! And what a sht!
But as you say, the timing (no pun) was lucky.

You have probably seen me mention L1 cams elsewhere.
I was told these were a race profile and normally too lumpy (or unsuitable) for street, but that they are fine in the G-W series.
But someone in OzGem(?) said L1's are mild etc.

But L1s are what the HDT used in their G-W Geminis (definitely for rally, but I believe circuit also) and a few others to get 220+HP from a G200W (with twin DCOE45s, a port job, and pistons that exceed the standard pistons' 180HP limit).

But I'm unsure how suitable L1s are with a turbo.