on exhaust and intake cams?? wouldnt they over lap or blow thru?

WTF are you talking about. Get the HKS 272 grinds, then you'll need a new tune.

he's referring to the cams have so long of a duration that they overlap and hes gonna lose intake charge because the exhaust is gonna be open to long...so a good answer would be......




on a turbo car no..u have the restriction of the turbo to allow u to run those cams perfectly. a supercharged car is a different story.

My bad, I figured he knew those were turbo cams. Hence why B switched over to the gmr cams.

cant every assume when it comes to these forums..u know that lol...i'd like to u running some gm racing cams

ok thanks. i did not know they were turbo specific grind. any place that will do them for a fairly good price. i was quoted $450.i heard there was a guy that does it for $300

what would be the best spring rate to get for valve springs? also whats the highest rpm we can rev to with out needing balance shafts

if that 450 is for blanks and the grind thats pretty good. if not its kinda pricey..i think this is the website that people get there regrinds done

http://www.flowtechnicsonline.com/

and if u need a spare set of cams for not having ur car down forever i have a set if interested

78lbs would be fine...get the supertech ones from www.dezod.com

and some people have spun it up to 7500..and higher...i wouldnt recommend over 7200

ok thanks haha car down ? its been down waiting for hahns kit for 3 weeks. but thats just for regrinds. thanks raven.

would anything bad happen if i got the 94 lbs?? they come with retainers but do i need new seats as well? and wuts the pros of getting new valves over the stock ones?

i dont see a need for getting the 94lbers but do what u want. the 78lbers come with retainters too.. when i did my valve train i bought some gm seats. they'll be fine

We normally stock the 78lb supertech kit.

Ok, real quick. Turbo likes more overlap, longer duration on the intake side, more lift on the intake side. Supercharger likes less overlap, longer duration on the exhaust side, more lift on the exhaust side.

Turbo cams on a super will normally kill your low end but can have slightly better high end HP then a super cam. Super cam on a turbo will cause you to have longer spool times (that blow through helps you spool up) and cut off your high end.

Moral of the story is that you will get the best from a cam designed for your type of forced induction.

GM Racing cam specs...haven't had them checked to see if they are accurate.

That's not really correct. Other than intake timing and exhaust lift playing their parts between the two cam profiles, generally turbocharged engines, in my experience, gain smaller advantages and can develop problems from high overlap than supercharged engines. I've experienced too high EGTs from blow through on large turbo housings and complete reversion on restrictive ones. Finding a middle ground between head flow, turbine housing and cam overlap is a science. ;)

The difference in horsepower so far with the only two aftermarket cam profiles available for the LSJ is probably due to the difference in how aggressive the duration is. The 272 is much less agressive @.050". Its one of many reasons this profile was chosen at the time due to it being a less aggressive ramp on a stroked hydraulic lash adjuster than something out of the Comp catalog as the 272s are base circle regrinds.

I posted dynos somewhere on the redline forums of before and after with the stock and 272 cams. There was a broad torque gain all across the operating range as well as a peak horsepower increase of 20whp. The cams also continued to make higher amounts of torque at higher engine speeds (which accounts for the peak hp increase) than the stock cams without suffering from any type of low end loss (they actually gained down low).

The GM Racing cams will show an even larger increase compared to both the stock and 272 grinds. Again, results were posted on the redline forums by someone other than myself and it should be easy to see by looking at the cam specs as to why the numbers come out to what they do. Without an actual dyno graph I can't comment on where torque was gained other than it was more than any other cam available so far.

witt. i have dyno graphs comparing each one. stock cams produce the most torque. 272's sound cool. the gmr's wax them both on a blower car.

the gmr cams don't die off at 7300 rpms. they hold power to 7800. the torque curve is a lot flatter. the car doesn't have a tendency to blow the tires off now. less peak torque.

i sent wes my findings in a pm. you are now finding out what happened on my car with those cams