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Old 07-23-2008, 03:07 AM   #1
joekerk
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Default AVCS better or non AVCS better for drag race

Hi bro, i am planning to upgrade my cams to cosworth 278 cams with MY04SPEC C head, wondering whether is AVCS a advantage to drag racing like 1/4mile drag or non-AVCS better on the high RPM.I also had Jun adjustable spocket . Which will be the best for beautiful power bend at high rpm.I will be using the TSR 70kit with a built engine. Heard from ppl avcs is very dangerous on high rev but if wan the best performance which will be better?

Any bro here can share it around before i go built my engine
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Last edited by joekerk; 07-23-2008 at 06:11 AM.
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Old 07-23-2008, 01:28 PM   #2
flycaster
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It's my understanding that AVCS was designed to help the bottom and middle end of the powerband, and by the higher rpms you're 100% "on the cam." In a full-on drag scenario, I can't see AVCS being any benefit whatsoever.
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Old 07-23-2008, 01:30 PM   #3
blowbyu24
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well it does help spool, so if the car will only ever be at the drag strip its not that necessary to have..but if your on the street and want that extra powerband and spool go with avcs
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Old 07-23-2008, 03:34 PM   #4
jays05
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Non-AVCS cams typically have more aggressive lobe profiles and more lift which would be better on the top-end.
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Old 07-23-2008, 04:08 PM   #5
Element Tuning
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You can have both an AVCS cam and a non-AVCS cam with the same grind (valve clearance being the main concern but in either case you could have custom pistons made). The AVCS allows the cam timing to be altered which in effect can increase power up to about 5k rpm and in some cases beyond but that would have more to do with the centerline of the camshaft.

For road racing or street using AVCS is a huge asset and will allow larger turbochargers to have a wider powerband. Those who have motor swaps and switch to a Hydra EMS than can run AVCS are always happy and impressed with the gains. In drag racing since you'll be leaving the line with anti-lag or launch control and rpms will typically always be above 5K rpm it doesn't really offer any benefits but it really wont hurt you either.

My suggestion is just to pick a cam with a proven track record that you will not have to use adjustable cam gears for. Many AVCS cams are built with the intake cams retarded and use the AVCS to correct that for lower rpm power and then return to a retarded state for more top-end power. With that said I've tuned EVOs that have picked up 25 whp while tuning with adjustable cam gears. This can be time consuming and expensive since you'll have to pay someone like me to tune various settings along with the dyno time. The EVO cam sprockets are easy to reach and there are only two where the Subaru will need 4 to be adjusted and fans will be grinding away at your arms as you try to adjust them on the dyno

Thanks,
Phil
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Old 07-24-2008, 12:20 AM   #6
joekerk
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element tuning , u r very detail, right now i got 4 Jun adjustable spocket. I am planning to get the cosworth head and cams set to upgrade on my head works.
I am mainly looking for drag. So u advise is to carry on with the avcs or use stop the avcs and use the Jun adjustable spocket for it seems i actually have them.
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Old 07-30-2008, 12:42 PM   #7
Element Tuning
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Quote:
Originally Posted by joekerk View Post
element tuning , u r very detail, right now i got 4 Jun adjustable spocket. I am planning to get the cosworth head and cams set to upgrade on my head works.
I am mainly looking for drag. So u advise is to carry on with the avcs or use stop the avcs and use the Jun adjustable spocket for it seems i actually have them.
I have made a ton of power with the JUN cams so if you have the time and money to dial in the cam sprockets I would say for drag racing, stick with it.

Thanks,
Phil
www.elementtuning.com
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