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i see, well that would make sense to adjust the intake side, but what about the exhuast. the faster you get rid of the exhaust gases the more effeciant the engine will be.
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Originally posted by GrooveNerd:
Does it change the duration, or the timing of the lift? It seems like it would only control the timing of the lift unless it slows down (or speeds up) the camshaft for a portion of a revolution
It only changes the valve timing points and the subsequent rpm range of the cam profile. Yes just like an adjustable cam gear would.
However it can't be manually changed like a normal adjustable cam gear can. Also the heavy weight adds significant parasitic drag on the valvetrain. That's part of the trade off of drivability verses performance.
No it doesn't change duration as it just could not possibly change the duration accurately and quickly enough.
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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That brings up a very good idea.
Oval port intake cams and Mazda 6 exhaust cams on a boosted car.
I notice the Mazda exhaust cams are quite long winded and also should use the smaller pitch chains.
The models show them to be a good match together.
They'd be good match for NA as well if you had adjustable cam gears for the intake cams.
I wasn't too impressed with the profiles of the 6's intake cams.
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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So how about an option for increasing intake duration for N/A. I did not see anything on that.
E0 SVT
Kids, yeah, I have kids. How many do you want?
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Originally posted by Bike2112:
So how about an option for increasing intake duration for N/A. I did not see anything on that.
Custom Cams... 
You can't just change the profile of said camshaft.
For instance variable valve timing only alters the cam timing points (i.e. VVT) or switches to a different/alternate lobe profile. (i.e. VTEC)
VTEC is about as close to having 2 different camshafts as there is because in fact there are 2 completely separate profiles on the cam.
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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Originally posted by DemonSVT:
Custom Cams...
Too much $$$
Thanks.
E0 SVT
Kids, yeah, I have kids. How many do you want?
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Originally posted by DemonSVT:
That brings up a very good idea.
Oval port intake cams and Mazda 6 exhaust cams on a boosted car.
I notice the Mazda exhaust cams are quite long winded and also should use the smaller pitch chains.
The models show them to be a good match together.
They'd be good match for NA as well if you had adjustable cam gears for the intake cams.
I wasn't too impressed with the profiles of the 6's intake cams.
Then how about this curve ball?
Jaguar S-type 3.0 VVT cams? Haven't amassed any useful cam timing information on it, only end play, journal-to-cylinder head bearing surface clearance, journal diameter runout limit and journal diameter out of round. Yet I do have lobe lift at intake and exhaust (.3688" and .3725" respectively). Much higher than the .188"/.188" found in the SVT, Escape, Taurus and 6 cams. Yet in my simulations, using the 6's durations as a reference point , I show using both Jag cams, rather than hodge-podging, produces a nice flat torque band from 4,000 to 6,000 RPM.
Driving the Caliber
Side project: The LT-5 Fiero is being born..
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Originally posted by Twisted6:
Then how about this curve ball?
Jaguar S-type 3.0 VVT cams? Haven't amassed any useful cam timing information on it,
Yet I do have lobe lift at intake and exhaust (.3688" and .3725" respectively). Much higher than the .188"/.188" found in the SVT, Escape, Taurus and 6 cams.
.188" lift is incorrect to use.
You need to be comparing effective lobe lift.
The normal cams effective lift is .386" - .388" (roughly 9.8mm)
Yes the Jag cams have less lift. They also have less piston to valve clearance so that makes complete sense. The Jag uses domed pistons while the regular 3L is relieved flat tops.
This is also part of the reason why I state using higher lift cams in a 3L may use up the small amount of clearance available.
From the dyno graphs I've seen of the Jag cams I am not too impressed personally. It is quite possible the Jag uses the same exhaut cam as the 6. So far that exhaust cam looks to have some promise.
As for better intake cams. You will have to look at the selection of aftermarket custom cams (mainly CAT Stage 3 or 4 - as they look nice) to better the SVT profile.
My statement of oval intake with 6 exhaust for boosted applications is a good one. It gives them a shot at a real exhaust cam that doesn't drastically choke of power right when the engine starts making it. You can't use SVT exhaust cams because of the pitch difference.
Also the combonation cuts nearly half the overlap verses the SVT setup which is paramount for running higher boost levels!
The oval intake cam is very well suited to boost. Valve timing right near TDC with quick ramps and not a lot of duration. The 1.8 follower ratio is excellent for boosted applications as well.
It would be interesting to see a high boost turbo try this...
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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Originally posted by DemonSVT:
Originally posted by Bike2112:
So how about an option for increasing intake duration for N/A. I did not see anything on that.
Custom Cams...
You can't just change the profile of said camshaft.
For instance variable valve timing only alters the cam timing points (i.e. VVT) or switches to a different/alternate lobe profile. (i.e. VTEC)
VTEC is about as close to having 2 different camshafts as there is because in fact there are 2 completely separate profiles on the cam.
Or buy a BMW. They have completely variable lift now on some of their engine lineups in addition to variable valve timing called VANOS.
It takes them just 180 ms to adjust the valve height + - 11mm IIRC what I read before.
Still, it still doesn't change cam lobe profiles.
Former owner of '99 CSVT - Silver #222/2760
356/334 wHP/TQ at 10psi on pump gas!
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