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OCC
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Discussion Starter #1
Here's some HKS camshaft information, directly from HKS USA. It took a while to get the info, but we're making some progress. They provided one dyno sheet... basically a stock supra with 3 different camshafts. Only trouble with this is that boost was at 1.0X kg/cm^2. Take a look at the posts... feel free to post any questions you guys may have... I think we can all learn from this.

ak
 

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It's interesting that the OEM cams didn't offer any low-end power advantage at all over the 264s. I'd like to see the same test at about 25-28 PSI .

Steve - 264/264
 
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seems like to me 264 is the way to go.. i heard 272 has a pretty ruff idle??
264 seems to offer a good high end..
 
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That graph is next to useless without more info. Without knowing what turbo combination the cams will be matched with, you can't know what to go with. If that is a stock turbo car, I am very surprised.

Is this a chassis dyno or engine dyno? What other variables?

If it's an engine dyno and the stock twins make 450 ps or so peak, then that would equate to about 441hp, or 375 rwhp with the standard drivetrain loss. 375 rwhp at 15.2 psi - unlikely, but not inconceivable. Now, 525 ps is 514 hp, or 437 rwhp. 62 rwhp gain by just moving to cams on the stock turbos? Doubtful.

More likely that's a chassis dyno with an HKS T04R turbo or something similiar. Still more power than I would expect to see at that boost level, but more likely.

Progress, yes. I applaud HKS for making that available.
 
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Certainly. Cams that are too large for the rest of the components in the engine system can certainly degrade power. For one thing, if the duration is too long and the overlap too large, exhaust gas can be forced back into the combustion chamber from the exhaust manifold, displacing incoming air from the intake port. What happens is the high pressure after the exhaust port is skyhigh at high boost on the stock twins, and when the exhaust valve opens to expel the combusted charge, it doesn't get out very easily, and you end up with more already-combusted air mix for the next cycle, and therefore less power.

It takes quite a large turbo to take full advantage of 272s - in my experience, T88 or bigger.
 

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Darren, in your opinion, what about the T72? :)
Peter

Walser said:
Certainly. Cams that are too large for the rest of the components in the engine system can certainly degrade power. For one thing, if the duration is too long and the overlap too large, exhaust gas can be forced back into the combustion chamber from the exhaust manifold, displacing incoming air from the intake port. What happens is the high pressure after the exhaust port is skyhigh at high boost on the stock twins, and when the exhaust valve opens to expel the combusted charge, it doesn't get out very easily, and you end up with more already-combusted air mix for the next cycle, and therefore less power.

It takes quite a large turbo to take full advantage of 272s - in my experience, T88 or bigger.
 

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OCC
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Discussion Starter #10
It's just very difficult to get any kind of technical information from HKS-USA. I have a contact from HKS Japan that has been very helpful thus far... I'll post 'their' information soon...

ak
 
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