Z06er

Tech Experts:

IN your opinion, what differentiates the cam shaft profile between road vs drag racing cams. I am looking for a reliable racing camshaft profile for a stock bottom end LS6/66 cc AFR 205/LG LT header/stock LS6 manifold/ported TB/Rollmaster/ported oil pump/3.73 combo?

Key is straight line high torque curve in 2nd and 3rd gear with power available to pull out of the corners. I noticed there are number of killer combos out there like the LG GX cams, TREX, FM 13 and the like, but wonder if there are applicable on a road course. Winding the motor out to 7000 rpm is not likely on most courses with my MN12/3.73 combo as my car weighs about 3100 pounds. The longest straight away is no more than 2/3 mile with a corresponding decreasing radius corner which usually requires serious braking and a 4th to 2nd downshift to boot. In addition, run times are as long as 30 minutes with the motor winding throughout the power band from 2nd, 3rd, and 4th and then back down as needed. Oil starvation is reduced but not eliminated via the Z06 pan and a 3 qt accusump.

So with all this in mind, I am starting to think the road cam is a different animal than the typical drag racing profile.

Should I consider:

Going with the existing camshafts as descirbed above and:
1. Advancing the cam 2-3 degrees?

Or go with
2 Go with a lower lift shorter LSA ? (e.g. ASA)

or,
3. Reduce the split between intake and exhaust and tighten up the LSA?

I noticed there are posts related to a T1 cam as well as a TRAK camshaft. Are these viable candidates or?

If I sound like a neophite, well I am. I want to learn but not by buying and installing everything that sounds cool.

Any advice would be appreciated.

SouthFL.02.SS

TSP225 is a great all around cam. You don't want to give up too much down low, nor do you want to wind it out too much up top.
A friend of mine who RR's in his '99 FRC runs this cam with some MTI Stage II 5.7L heads and loves it.

Bombguy99z28

You hit it on the head really. You don't need serious power down low, but a very broad power band/torque curve. Personally, I'd run a less aggressive setup since 20-30 min at high rpm is gonna wear a lot more on parts than 11 second spurts. Honestly, road racing you don't need to mod the car for power until you get really good. 9 out of 10 people (including me) will drop lap times drastically just from practice faster than they ever will by throwing HP at it.

Get an aftermarket belt tensioner like the Katech while you're at it, cause that stock pos will give in the corners/high rpms and your belt can come off. At least, it did on my camaro, I haven't even really looked at my corvette to see if the tensioner is different. Corvettes might not have that problem.

MountainMotor

iTrader: (2)

Yea, I'd say a broad range cam would be your best bet. A drag race cam usually is a lot larger than a road race cam because the drag racing runs to a lot higher rpm's like you said so I'd go with a healthy cam but nothing too large. You will want good torque to pull out of the corners but with the straights you don't want the cam to die out either. I would go more for a nice sized "street" cam rather than "strip" cam. I wouldn't go as big as a T-Rex for what your doing. I really like the T-Rex but I don't road race either. You won't pull, as much as some other similar but smaller cams, until you hit about 4000 with the T-Rex.

jrp

iTrader: (16)

you have to look at lobe profiles and spring selection as well. most of the cams you listed and see guys running are really aggressive lobes, comp XE-R. while great for making great power and stints at the drag strip where 6500+ rpm is seen for a few minutes max depending on how many runs they get in. in a road racing application, sustained time in the 6k+ range can be a few hours. a really aggressive lobed cam will be murder on your valvetrain in that situation. i had a custom ground cam for my applicationn which was HPDE's, the lobes are an XE and an in between (XE and XE-R)

SouthFL.02.SS

Very good point JRP. ASA, with its low lift and lazyish lobe profiles would be a safe bet wouldn't it? Or maybe an ol' MTI T1? (Perhaps the thread starter was headed in the right direction, hehe).

DONAIMIAN

iTrader: (18)

I run the MTI T1 and plan to do as many track events this year as I possibly can. Right now im spinning the motor to 6500, but will mostlikley bring that down after my first track event depending on where and when I shift the car and what not.

DONAIMIAN

iTrader: (18)

And im running manley single springs and titanium retainers BTW.

SouthFL.02.SS

Do the road racers here have to settle for old grinds on milder lobes? I know that on a stock bottom end, and with your average valvetrain, we don't want to be spinning over 6K for sustained periods of time. Most the new grinds involve aggressive lobes, hight lift and big duration- all killers for sustained rpm. But do we have to settle for what an ol' T1, C1, ASA will give us? Isn't there anything new out there that we can use? JRP is grinding his own cam- he's got the right idea.

It's funny, 'cuase the only reason I still frequent these boards is for my future ls1 roadracing buildup. Funny, because at the end of the day, with all the new products out there, I'd probably end up going with a GMHPP LS6 CNC head/ ASA cam combo (stuff that's been available for years now).

Any thoughts?

TAF Motorsports

iTrader: (10)

There is the also GM Cup cam GM part # 88958606 (239/251 .570 .570 106ls ) with a tighter LSA, but will require PTV to be checked on stock heads and definite valve reliefs on milled heads if you get the 59CC GMPP heads. Best bet would be heads of your choice and a custom cam which would cost no more that the GMPP pieces.

SouthFL.02.SS

Cup cam takes us back to that old parts bin again

Can't we have the best of both worlds? A cam that pulls as hard as say, a T1, up to 6000rpm, but has the capability of squeezing out those extra 15 ponies up to 6900ish like an X1 (if you need it to)? Run 2 shiftlights- one for your typical laps, one for that extra oomph when needed? Plus, easy on valvetrain?

Wouldn't FUTRAL's F13 figure well given these parameters (I know the lift numbers are high though)? Aren't the cam motion lobes softer than XER? Maybe an F4 or an F10 would be ideal (226-228ish duration, .575 lift)?

DONAIMIAN

iTrader: (18)

As of right now my car puts out 400/395 with the T1 so thats good enough to get me around the track. If anything I need to pull weight from the car. At one while I was looking at replacing the cam and I was looking at the GM Cup cam and the MTI R1(also on XE lobes) but to get on the road course the last thing I need is a bigger cam, the T1 makes enough power, for now anyways. So far its nothing but stret driving on the car and im comming up on 40k miles on the springs.

Z06er

paging predator and J rod....your thoughts?

I agree with SouthFLSS02, with all the technology available, there has to be a better way. Killer torque, uses pump gas, and good reliability where you are not changing valve springs all the time, can't be an impossible task.

Bombguy99z28

Honestly, if you road race a lot changing valve springs isn't a big deal. You'll be fixing a lot of parts year to year, its just a lot of wear and tear. Road racing isn't like drag racing were power is the end all be all. Car setup and driver ability mean a lot more than horsepower.

Z06er

Bombguy99Z28

Yes you are right, road racing is different from drag racing. But I like to think that with the right set up, I can minimize the wrenching of the car as much as possible similar to what Stang Killer has in his car. SouthFL02SS is right on with the technology solution-look at the LS7-.590 lift cam, Ti valves, Ti rods and dry sump in a car you can drive off the lot to the track and back.

Short of buying a new Z06, there has to be a better way...

J-Rod

Listen to JRP. You can run any of the more "exotic" lobes, but in a "true" road racing setup, it'd be hard on valvetrain. If you really want to run all day, you need a less agressive ramp rate, etc... to promote reliability. You may give up some peak HP, but, you'll gaina lt more life, or plan on making the valvetrain a much more regular wear item like pads and rotors.

In short drag race lobes aren't road race lobes....

Z06er

Thanks J Rod!

DAPSUPRSLO

iTrader: (14)

One of the biggest items of concern in an endurance application is just that, endurance. Something you really need to be concerned with in this kind of application is a valve train's ability to control things for hours at a time at wot. Generally speaking a cam lobe designed for an endurance app is a little on the slower less agressive side to promote less problem caused by the requirments of crazy spring pressure. With hydraulic lifters, spring pressure is even more of an issue then with solids.

As far as picking valve events to suit the entire combination and wants and needs (power band, how much power in the power band) as well as things you are willing so sacrifice (driveability) need to be considered. Obviously a motor which spends most of it's time in the 1500-5000rpm range has requirements for drastically different valve events then one that spends most of its time in the 5000-6900rpm range. Good luck!!!

11 Bravo

iTrader: (3)

I could be wrong, but isn't the Cup cam run in the C5R race motors?

Z06er

Well, I found this thread. Fascinating. Sort of addresses many of my questions.

https://ls1tech.com/forums/showthrea...ht=torque+cams

I believe the C5R has a Katech Proprietary grind to take into account the Kinsler Fuel injection, restrictor plates and track the car is running at. I'd bet the LeMans set up is different from the cam used at Road atlanta.