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Yea actually 980 on both sides and duration @50 is 282/288
For what it's worth, I have a 430 SBF race engine with SC1 heads, twin 80mm turbo's and my cam is .750 lift and 262 int...276 ex dur @.050. It spools quick, I shift around 8000 rpm and car runs in the mid to high 6 sec range in the 1/4 mile. I've always been told to cam a turbo motor as if it was naturally aspirated. I personally would not use the cam you presently have. I think it's way to big on both lift and duration. My advice would be to keep the duration @.050 in the 260ish range for the intake and 270ish for the exhaust. I personally know that works on my motor which seems similar to yours.Your cam is enormous.
 

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I agree KevinL. I have also heard that the boost may increase your usable rpm range by about 1000 rpm. That's about what my experience has been.
I remember a good while ago there was some discussion about quantity of overlap in a turbo cam. Using the event timing to illustrate how much overlap and boost loss a cam would have. I would guess that the cam in question here would have a LOT of overlap regardless of how wide the LSA is. I would lay money that a simple cam change would completely change the ability to make boost at low rpm.
 

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Whats your lash settings?

Maybe try opening it up more. See if you can find out the last ramp on the cam lobes to determine how large in lash you can go. Open it up to make the cam seem smaller and see if it improves
 

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Discussion Starter #49
For what it's worth, I have a 430 SBF race engine with SC1 heads, twin 80mm turbo's and my cam is .750 lift and 262 int...276 ex dur @.050. It spools quick, I shift around 8000 rpm and car runs in the mid to high 6 sec range in the 1/4 mile. I've always been told to cam a turbo motor as if it was naturally aspirated. I personally would not use the cam you presently have. I think it's way to big on both lift and duration. My advice would be to keep the duration @.050 in the 260ish range for the intake and 270ish for the exhaust. I personally know that works on my motor which seems similar to yours.Your cam is enormous.
My last motor was a Yates head and it was nothing fancy they were junk heads same cu in as this motor but it was a 4in stroke and lil more bore but my cam in that motor was almost like yours it was 750 lift @50 it was 264/269 116 lob cep and I turned that motor 8500 and it spooled great to it did better than this motor for sure. I was shocked when I got this cam on how big it was but figured that's what I need cause the heads I have now are alot better .
 

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KevinL on the right track. Current cam might be OK NA to 9000+ but don't see it working well boosted unless sprayed to 5500.
 

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Discussion Starter #52
And I'm not really sure why i was sent a can that big but figured with the heads and what I had it would work but I'd hate to have to change it cause pushrods would be no good and probably have to reshim the rocker stands and alot of trick stuff done to it already .
 

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Great heads usually need less cam and definitely don't need the cam to crutch any shortcomings like a shitty exhaust port compared to the intake flow potential. Generally speaking lift is in most cases free performance these days. However in the OP's case it only adds to the problem making the area under the curve even greater magnifying the overly large duration values. Lift is a balancing act with duration, basically you have to open the valve "X" amount in so many degrees. This is usually handled by the lobe designer and the person spec'ing the cam must account for application details like turbo charged, supercharged, cylinder pressure, component weights, RPM, etc. In turbocharged applications opening the exhaust valve early is necessary and care must be taken when specifying an exhaust lobe. The number of max effort high lift exhaust lobes for this kind of cylinder pressure is very limited when you get in the 270* - 280* range. Many times when you see someone breaking exhaust rocker arms or bending exhaust pushrods someone has used an intake lobe on the exhaust. Most modern intake lobes are asymmetrical, fast open/slow close. Exhaust lobes on turbo applications should be less aggressive at a minimum or even the opposite of the intake valve ramps meaning slow open/fast close but care must be taken to not bounce the valve on the seat closing the valve.
 

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Well perhaps you can try running that cam but give up on the idea if making boost at 4000-4500. Give it more rpm on the brake and see if it comes up. It probably will just require more rpm which might not be a bad thing
 

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Discussion Starter #56
I had my cam spec'd by "Bennett Racing", an I'm very happy with it.. Just say...
Well perhaps you can try running that cam but give up on the idea if making boost at 4000-4500. Give it more rpm on the brake and see if it comes up. It probably will just require more rpm which might not be a bad thing
I don't no if the converter will go to much higher lol it's at the point now it takes forever to get on 2step so I got to get it better hard to race like this
 

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Discussion Starter #57
I had my cam spec'd by "Bennett Racing", an I'm very happy with it.. Just say...
My cam in my other motor was from him it worked good me and him don't see eye to eye now so I just got it straight from cam company.
 
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