Quote:
Originally Posted by PAUL K
Good thread and a lot of good information. However, I feel you need to match the cam with the parts you are using and you will generally need a tighter lobe separation than 114 if you're looking for cutting edge performance. However, I cannot stress how important it is to match all the components! The new norm is 10 second naturally aspirated pump gas street cars.
In 2006 I was running my 80 T/A with a 9.1 compression 455, ported cast iron heads, 3.42 gears, tight 11" Coan 2800 rpm converter and a Comp hydraulic roller 242/248 with an 110 LSA. Weighing over 3900 lbs. the best ET was 11.35 @ 119.3 mph.
For the last 2 years I've been running the same 3.42 gears, the car has lost 100 pounds and uses 318 cfm E-heads, Torker II and a tight 10" converter with a solid roller 259 @.050 on a 108 LSA, I've only had it to the track 3 times but have run consistent 10.7 @125 mph.
A friend was running a 9.1 455 with E-heads, 10" inch converter and 3.55 gears in a '64 GTO weighing 3670 lbs. and has run 11.2 @ 119 mph using the dreaded Comp XR288HR which has a 110 LSA.
My brother ran a 9.1 compression 455 with 310cfm E-heads, a solid roller with 254 duration @ .050 ground on a 108 LSA, and went 10.8 @ 124 mph the first time out, using a tight 10"
converter, 3.70 gears and weighing 3720 lbs.
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For many years most of the street/strip stuff we built was 108-110 lobe seps and we made good power, but when we started going to wider lobe seps over 15 years ago we found we could get much better driveability, way less "stink" out the tail pipes and extend the rpm range, this was with flat tappet solid lifter cams. For most of the solid roller race stuff we still used 106-108 as we only had cast cranks to work with but once the forgings became available we started going to wider lobe seps and in a lot of cases less duration and ended up with more power and quicker ET's at the track with more rpm capability. I feel a lot of the gains we've seen with the wider lobe seps also has to do with the increased efficiency with the cylinder heads. No doubt you can make some great power with the tighter lobe sep cams (we ran a 104 LSA in our 65 GTO), but I found at some point you will hit a wall. I disagree with your statement that today's cutting edge performance is made with tighter lobe seps, the guys making big NA power are using wide lobe sep cams and turning big rpm to make the power they do and this isn't specific to Pontiacs.
I do agree with you 100% that whatever route you decide to take matching all the drivetrain components is critical to achieving optimum performance. This typically takes time at the track to sort out all the details, ta man is a good example of that. You can't just keep throwing parts at something if you never optimize what you already have and make incremental changes which in some cases might make things go backwards before you can go forward, but if you make too many changes all at once you will never really know which ones are helping or hurting.