Unconventional Cam Choices
02-01-2007, 06:56 PM
#1
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Unconventional Cam Choices Lets look beyond the normal z06 and 22X cam selection for FI Cars, have any of the BIG guys run large split pattern cams like a 230/242 or larger 114.5 lsa to get those huge turbo's to breath up top?
Everything i have learned in thermodynamics, and Engine Theory (as well as some real expensive engine simulators) tell me that it'll make more power and carry better with more exhaust duration to get all those gasses out and turning the turbo.
Besides it's only 8* overlap......
Everything i have learned in thermodynamics, and Engine Theory (as well as some real expensive engine simulators) tell me that it'll make more power and carry better with more exhaust duration to get all those gasses out and turning the turbo.
Besides it's only 8* overlap......
02-01-2007, 10:29 PM
#4
I just ordered a custom grind through Stenod....BIG:
24x 23x, 64x, 61x on a 114.
They picked a bigger one for me at first but it was made for 7500ish rpms and that was just a little scary for me running 18-20psi. The cam they made for me shold be good to shift around 7k or 7200.
24x 23x, 64x, 61x on a 114.
They picked a bigger one for me at first but it was made for 7500ish rpms and that was just a little scary for me running 18-20psi. The cam they made for me shold be good to shift around 7k or 7200.
02-02-2007, 08:28 AM
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what would you gentleman recommend for a D1-sc set up on a forged 402...l92/l76. im lookin to make 650ish on pump gas. I was lookin for something along the lines of 23x/23x...595/.598 on a 115lsa??? thanx for the input.
02-02-2007, 11:30 AM
#7
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Why kill the car with a big cam ? Making a rev happy turbo motor, doesnt necessarily make it any faster than a smaller cammed motor, that drives well everywhere, and still produces the goods.
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02-02-2007, 12:11 PM
#9
Maybe I mis-understood the question, but I thought he was looking for Turbo guys running split pattern cams. Just about everyone runs a split patter on a blower.
I'm running a 224/236-114 with my T76GTS / 388 LTx combo. I tried a 226/226-114 cam and was unhappy with the results, so I put the old "blower cam" back in. Since I've gone 146 mph in the quarter on 17 psi boost at 3750 lb using a log header, I tend to think the cam's not hurting me.
Mike
I'm running a 224/236-114 with my T76GTS / 388 LTx combo. I tried a 226/226-114 cam and was unhappy with the results, so I put the old "blower cam" back in. Since I've gone 146 mph in the quarter on 17 psi boost at 3750 lb using a log header, I tend to think the cam's not hurting me.
Mike
02-02-2007, 12:18 PM
#10
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Was there really a marked difference between the 2 cams ?
Id say the extra duration, and possibly overlap would be more likely to hurt a log setup, than a decent tubular setup.
TBH, and Ive said this before, with boost and tuning.....unless cam choices are extremely bad, pretty much most small-mild cams, will have the ability produce excellent power everywhere.
Big cams may have some ability to make good power at the top end, and also the ability to kill it everywhere else off boost.
Id say the extra duration, and possibly overlap would be more likely to hurt a log setup, than a decent tubular setup.
TBH, and Ive said this before, with boost and tuning.....unless cam choices are extremely bad, pretty much most small-mild cams, will have the ability produce excellent power everywhere.
Big cams may have some ability to make good power at the top end, and also the ability to kill it everywhere else off boost.
02-02-2007, 12:38 PM
#11
Originally Posted by stevieturbo
Was there really a marked difference between the 2 cams ?
Most people believe that a reverse-split is needed when you have alot of backpressure and/or a log header, but I have seen zero dyno evidence that this is true. In fact, the opposite may be true. I do know that Cam Motion really pushes the reverse-split turbo cams and when you press them for a reason why, they start blowing smoke.
I would really like to add something like 12 deg overlap just to see how bad overlap really is on a turbo motor. The new cam would be something like 230/242-111. It would be really interesting to see once and for all how that extra overlap would compare to my 224/236-114.
Mike
02-02-2007, 12:42 PM
#12
This 222/228 cam I have in my car went 124mph in the 1/8 with the a twin T67 346. Only thing you can do is try it and see what happens - you will find that your tuning knowledge and overall combination will outweigh a few degrees duration here and there on a camshaft 
02-02-2007, 12:54 PM
#14
Originally Posted by kp
you will find that your tuning knowledge and overall combination will outweigh a few degrees duration here and there on a camshaft
02-02-2007, 12:56 PM
#15
Originally Posted by motorbuilt
What do you guys think of reverse splits on turbo cars with well flowing heads?
02-02-2007, 01:35 PM
#17
Originally Posted by stevieturbo
How does your boost vs EGBP compare Mike ? with both cams may be interesting ?
Mike
02-02-2007, 01:54 PM
#18
Originally Posted by engineermike
I agree that if I had a trans-brake and your suspension and weight, I would be in the 8's right now. But, the engineer in me likes to extract every bit of available power out of the engine rather than make the car launch.
02-02-2007, 01:57 PM
#19
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Originally Posted by engineermike
I don't have numbers for the 226/226 cam, but with my current 224/236, I'm at 17 psi boost and 34 psi backpressure. I was as high as 48 psi backpressure until I changed the muffler from an Aerochamber to a Magnaflow.
Mike
Mike
Was the 14psi change down to a muffler swap only ??
02-02-2007, 02:19 PM
#20
Originally Posted by stevieturbo
Why kill the car with a big cam ? Making a rev happy turbo motor, doesnt necessarily make it any faster than a smaller cammed motor, that drives well everywhere, and still produces the goods.