Need some input on bigger cams for our 42r setup
Aug 13, 2007, 07:17 AM
#16
The issue with the cams you are presently running (BC 280) are twofold:
- The LCs for both intake and exhaust are much too far advanced (106/106) for the rpm ranges where the GT42R makes power.
- The lift on the BC 280s is reported to be 10.8/10.4mm for int/exh respectively, which is fine for a stock head, but is not enough for a ported head. Do you have any flow data for your ported head?
What you need is a cam set that offers enough lift to maximize the flow potential of the ported head, enough duration to support high rpm power, and is timed to maximize power in the rpm ranges where the turbo runs most efficiently. So long as we get the first two parameters within range, the third is easy enough to manipulate with a set of cam gears.
As for off-the-shelf cam sets, the Tomei 280 looks like a good starting point on paper. The Buschur cam set is what that camp uses. Apparently it works well, although we don't have any information about the specs to discuss.
One person who has been doing quite a lot of grind-and-test work in this area with cars of similar capability is Greg at GSC. If I were in your present position, I would certainly give him a call and speak to him about his obvservations.
- The LCs for both intake and exhaust are much too far advanced (106/106) for the rpm ranges where the GT42R makes power.
- The lift on the BC 280s is reported to be 10.8/10.4mm for int/exh respectively, which is fine for a stock head, but is not enough for a ported head. Do you have any flow data for your ported head?
What you need is a cam set that offers enough lift to maximize the flow potential of the ported head, enough duration to support high rpm power, and is timed to maximize power in the rpm ranges where the turbo runs most efficiently. So long as we get the first two parameters within range, the third is easy enough to manipulate with a set of cam gears.
As for off-the-shelf cam sets, the Tomei 280 looks like a good starting point on paper. The Buschur cam set is what that camp uses. Apparently it works well, although we don't have any information about the specs to discuss.
One person who has been doing quite a lot of grind-and-test work in this area with cars of similar capability is Greg at GSC. If I were in your present position, I would certainly give him a call and speak to him about his obvservations.
Aug 13, 2007, 07:39 AM
#18
And that may not be by accident. I feel as though the 10.8mm lift of the JUN set may leave a little something on the table with this type of setup (especially with a ported head), but only real-world testing can evaluate this.
Aug 13, 2007, 06:26 PM
#23
Just to toss the idea out there, Crane has quite a few grinds for the 4G63 that they don't advertise. I don't know how many will work on the EVO, as last time I called I was interested in the older 4G63 from the DSMs. They have several specifically setup for a motor with solid lash adjusters to help deal with very aggressive ramp rates.
Valve acceleration rate is where you can make a ton of power. It won't look as "nasty" on paper but it works. You really don't need 300 degrees of advertised duration on a 4-valve motor to make power to 10,000 RPM. 230+ at .050" makes for a nasty cam though and this is likely the reason the Jun 272s make more power then the HKS 272s as the Juns I believe are 235 degrees at .050" where the HKS are 218 degrees. That and more lift...
Forced Performance also went in this direction on their cams. Last time I talked to Robert they were working on a much more aggressive camshaft for all out race setups on the EVO.
Valve acceleration rate is where you can make a ton of power. It won't look as "nasty" on paper but it works. You really don't need 300 degrees of advertised duration on a 4-valve motor to make power to 10,000 RPM. 230+ at .050" makes for a nasty cam though and this is likely the reason the Jun 272s make more power then the HKS 272s as the Juns I believe are 235 degrees at .050" where the HKS are 218 degrees. That and more lift...
Forced Performance also went in this direction on their cams. Last time I talked to Robert they were working on a much more aggressive camshaft for all out race setups on the EVO.
Aug 14, 2007, 12:11 PM
#27
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Great Cams I am using the S2s and I have great top end power... Amazing Cams... Also after seeing your setup have ordered the ETS manifold but not the twin scroll the single scroll T3... Your setup is killer...
Do update us with the results...
Do update us with the results...
Aug 14, 2007, 07:22 PM
#30
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Its not a joke. The guy is on here. The guy is to busy working to be on here like you and me. The best thing about it is his motor revs to 12k
. 2.1L designed by his in house mechanic which happens to be a mechanical engineer. Full boost from 6100-12000rpm with a small shoot that kicks off at 3500rpm at WOT.
The car is just plan nasty. I drove it on the street for a day its no fun at all. Everytime the car is out new slicks, swap plates if needed, plugs and 18 gal. of vp import.
It evo is nothing compared to his twin turbo DB9.