tgcounts

Hi all,

I'm having the hardest time choosing the right combination for my LS3 Corvette. I've got a (vastly) different opinion from every person I seem to talk to. I drive (not trailer) my Corvette to many HPDE events throughout the year. I know someday I"m going to regret it when things let go but I really enjoy driving the car when I do.

However, the car spends its greatest amount of time on-track running hard at high RPMs (Barber Motorsports, Road Atlanta, Roebling, etc) for extended amounts of time. I'm not a street racer or a drag racer. Peak HP is not my thing, but 'reliable' torque is important.

I'd like to keep the bottom-end stock for now so P:V clearance is an important consideration too.

I've been recommended a 231/236 .644/.613 LSA 113 which doesn't strike me as something I'd want to track. It seems rather intense for a road cam. I think I'd be changing springs 4 times a year.

I've been recommended 235/234 .621/.612 (LXL exhaust lobe) that actually feels pretty good for what I'm thinking about. LSA 113 I understand the LXL lobes are road course friendly.

I've been recommended G6X3 (who knows the grind) but it too 'sounds' radical for a road course from what I read on the forums.

I've been recommended 230/234 .612/.598 (XFI & XER Lobes) w/ LSA 114

I've been recommended 235/251 .621/.624 LSA 113. That split seems huge...but I'm just learning so what do I know?!

Whatever cam I choose, I'll certainly install BT Platinum springs that match the lift.

I'm also wide open for heads. Texas-Speed, TrickFlow, Mast. I'm leaning to the PRC 255 & the TrickFlow 255 heads. I was reading that the TrickFlow 235's have excellent velocity for the LS3 but as I said, I'm still learning.

It adds up to a lot of money and I sure hate to make a mistake and go too big on the cam and have something that won't last on the road course. Same for the heads...wanting good flow that produces strong torque.

BTW, I do have Pfadt headers, a Breathless CAI, and a Jerry Onks tune. I run R-compound tires at the track that I trailer behind my car.

I really appreciate your informed opinions (and experience).

Tom

bosco022

Something that is torquey and pulls hard between 3500 and 6500 is really all you need.

The SCCA Trans Am 2 cars used forged, stock compression LS3, with the ASA .525 226/236 110 LSA cam. Unported heads and despite using a restrictor make up to 460 at the wheels. These cars are super quick. GM sells the crate, (ASA cammed) 525 HP (flywheel) LS3 for 7500 bucks, makes that number with just header and tune.

The ASA cam or something similar would fit your needs for a dual purpose cam.
We tested the ISKY 280/290 which is kinda similar, 530/540 232/242 113 and it made about 15 HP better than the ASA yet is still pretty mild and easy on the valve train.
Both of these cams have been known to fit in stock short blocks.

For your purposes, I would stay away from the high lift cams

tgcounts

I'm running 420 RWHP (I forgot my TQ, I'll look it up when I get home) with my current light mods. Just setting a baseline where I am now. I would guess that would equate to approx 490-500 at the engine.

hungryhippo

You want a mild cam like the tsp ls3 stage 1 or katech torqer. I run the 230/234 cam but i usually keep my rpm under 5000.

bosco022

420 is a pretty good number, you may just want to improve the suspension, brakes and the Nut behind the wheel before getting in the motor.

You have to remember there are some pretty fast SCCA T1 LS3 type Corvette's and similar NASA cars out there that have yet to go in the motor.

tgcounts

You're absolutely right about the nut behind the wheel. I'm working on tightening that one up too. It's got a lot of threads showing!

Regarding the suspension; I didn't get into that but right now I've got DRM Bilstein shocks, DBA rotors, EBC Bluestuff pads, Quantum Brake cooling (with the ducted vents instead of the fog lights), and mild camber. (-1.5/-1)

Z06 oil cooler but needing a bigger radiator (240 water temps)

bosco022

Sounds like your car is fairly well set up for HPDE events, my advice would be at this point...don't go in the motor, you have enough for now. Hire a true, professional racing coach for one weekend. You will gain more.

Then later, if you are still "hooked on the crack" and want to move to competitive W2W racing...get yourself a purpose built racer and do not build your street car into a racer.
Just my .02

Bosco

RDnomorecobra

you have seats, harnesses, HANS?

nut behind the wheel,
safety,
cooling,
brakes,
suspension,
nut behind the wheel,
motor

is the order I would be, and have been, doing things in.

LateBreak

This is some very sound advice. A tube-frame stock car type chassis will be cheaper in the long run. I'm currently building a C5 into a racecar (for a series that doesn't allow tube chassis) and it adds up quick even on the initial build, now throw in some future crash damage and it's an expensive way to go.

For your purposes, I'd focus on peripherals that help at your track outings, things like tools, enclosed trailer, EZ-up tent, etc. Going into the motor for a cam can help your hp, but stands to hurt your reliability and the rest of your drivetrain, requiring more costly upgrades. It also magnifies mistakes, so something that you might have driven through before turns into a car-totalling wreck. If you want to mod the car, reliability upgrades pay dividends versus speed upgrades.

troyguitar

For about the same cost as a cam and heads plus install, put a shifter kart on your trailer and learn to drive that thing. It will make the Corvette seem slow and easy in comparison.

bosco022

Also, as you move up in power, and running on comp tires, oil control becomes a serious problem. This is especially true of the LS3, which has had more problem than LS1's and 6's.

The LS3 really needs a dry sump system for effective oil control.

427ZM

Of the cams listed, the reverse split cam would be best for low end torque, but would run out of air up top. Also, running LXL lobes, you've got softer lobes that'll work well w/ valvetrain components. The 235/251 will produce the best power of the bunch, but being on the smaller cubes of the LS3, it won't have the torque down low needed for slow corners. Personally, I'd look in the comp catelog and look at HUC lobes. These lobes are large lift lobes, but are meant for road racing. They're soft on valvetrain components, and are meant to be driven at high RPM's constantly.

On, and the Trick Flow heads would be awesome! Mill them for higher compression and you'll have a heck of a combo.

NOSLO6

Katech's Torquer series cam was developed with your purpose in mind. It was wonderful in my LS3 and Katech certainly has real world track experience to apply.

tgcounts

First of all, kudos to Jeff for pinging me about my choice. I am remiss not to give the results of my decision.

I worked with Martin Smallwood of Tick, who, by the way is a genius and awesome. We discussed my desires and the compromises I would be most comfortable with and came up with a great final cam that honestly, I freakin' love.

So you'll understand my whole package, here it is:

TEA Trick Flow heads x255
50 degree valve cut / 5 angle
PAL 1215x Springs w/ Titanium Retainers 165-405#
Milled to 66cc
Cometic .040 Headgasket (figure 11.5:1 CR)
C5R timing chain
Morel 5315 Lifters
Comp Trunion Upgrade on stock rockers
Tapered Pushrods
LS9 Spark Plugs w/ MSD wires and insulators
Pfadt Tri-Y long tube 1 3/4" headers
ATI harmonic balancer
Dewitts Radiator w/ dual spal-fans
Accel Supercoils (whatever)
and....

Comp Cams 13472 QXX/ 13050 HUC 227/239 .624/.610 113LSA +5

I can't get any more specific than that. These are actually reasonably gentle lobe ramps. I am shooting for TORQUE over HP.

Tick prepared my heads/springs so the shimming was perfect. Martin handled all that.

I have a roll bar, racing seats, 5-pt harness, all Wilwood brakes (Aero6 and FNSL) running Poly-H pads and cooling ducts to the rotors. Added the biggest Setrab Oil cooler I could fit, Improved Racing oil thermostat, and an Accusump.

LG Motorsports GT CoilOvers and G1 Sway bars w/ quiet end links.

Monitor everything with an AEM AQ-1 for oil pressure, oil temp, water temp, AFR, brake pressure (fronts) and a VBOX for 10Hz GPS.

I still want to either change to a dry sump oil or add the Improved Racing pan baffle for oil. My AEM still tells me I'm "generally" okay though with pressures. Analyze my oil every 2nd outing.

THE FINAL RESULTS: 505 RWHP/505 lb-ft.

naturally aspirated

with a good tune, I have a slightly choppy idle that settles out nicely once warmed up. 12:1 WOT AFR. Pulls out of a corner quite well.

I'm pretty happy with it. Bottom-end totally stock (so far)

Hi Volts Z06

All that money and still no dry sump? Damn..... Good luck.

FASTFATBOY

LS3 with bolt ons and a tune makes a lot of steam, personally I would spend the money on grip and seat time.....not more power and less reliability.

What lap times are you running at Barber on what tire on both setups?

64drvr

505rwtq in a stock rotating assy LS3 is no joke.

Hi Volts Z06

I run a bone stock, LS-3, 480hp crate motor with no other bolt on's than the dry sump and an Evans water pump. The car made 448rwhp and over 460 lb fts of torque before we DETUNED it to run ST-2 with NASA. The dry sump doesn't just add reliability- it adds HP due to the scavenging effect.