GettReal

SO my brand new built for the 2nd time 383 stroker has oil pressure issues, I'm thinking the bearings are wiped. So going to tear it down to replace them and while I'm in there Im contemplating putting in a new cam. I really think my set up is underpowered to what a 383 should be, so maybe time to put a bigger cam in there while its apart. Is there such thing as too big? if so, I want to be right below whatever that is

Right now there is a 232/241 .570”/.559”

Thoughts?? What are the best kind of specs for Road racing?

kmagvette

I finally did a cam...nothing crazy, just a 571/574 228/230 ish cam, GMPP heads with CHE upgraded rockers, 918 Springs, and a 90mm intake. After a conservative tune focused on A/F not power, it still rolled in the 440's at the wheels with just under 400 ftlbs over a pretty wide band. Dyno sheet is a nice picture but otherwise BS. At a very cold Watkins Glen I was able to run a low 2:05 and hang with the best piloted C6Z I know of; it has roughly the equivalent suspension mods to mine. It felt like the C6Z still has me in the torque department...no replacement for displacement. The block and rotating assembly are still stock.

On the downside, I think I get to rip the engine apart again this winter because the cylinder walls barely show signs that a cross hatch pattern ever existed. Wouldn't mind overbuilding the bottom end for peace of mind.

Any Trackmasters in your future?

TriplBlk

I've been contimplating this as well, I feel that the MS3,MS4 cam is something to consider. They're high rpm cams and when racing that's really the place where you spend most of your time.

AU N EGL

MS3 and MS4 have too much lift.

Stick with lifts no more then .590 - .595

the better cams for road race reliability use lifts only to the mid .570s

one of the top road race cams is a 20 year old design.

The GM Cup cam 88958606
239/251 570/570 106

TSP Torque 2 may be biggest cam for reliability
232/234 595/598 112

Comp Cams RR recommendations same as Torque 2
232/234 595/598 112

Cane has a road race cam that may be a torque monster
218/224 585/585 110

LG has some great RR cams too
LGx1 or x2


Something to think about for road course use:

Most road courses are corner after corner after corner, connected by short straights, with an occasional long straight.

Generally a smaller exhaust is hotter off the turns and bigger exhaust is hotter at the top. So you will have to make the call here. Remember, exit speed is for the whole straight.
However, if this is fender to fender, those last few mph make a big difference in passing.
I would focus on coming out of the corners, since that will affect lap time most.

non of these cams will be dyno kings, but that is not what your looking for.

good Luck

TriplBlk

Please explain why having too much lift is a problem? Because it wears out your valvetrain faster?

crainholio

Here's what I was taught when I worked at a marina that built offshore racing engines...think WOT for 80%+ of over a half-hour at a time, just coming off throttle for waves when the outdrive leaves the water and then going right back to WOT.

More lift means working the valvetrain harder, and when you're running 30min+ HPDE sessions or even longer competition events it takes a toll on the parts.

Springs fatigue sooner, lifters are travelling farther in the bores, valves are travelling farther in the guides. More motion means more friction. More spring compression means faster fatigue on the spring wire.

And then there's trying to keep the valves under control for the WOT blasts down the straights. Add a lot of spring pressure to do this, and the hydraulic lifters become a weak point if they're not designed for the extra force applied to them.

We were using solid lifters, rev kits under the heads to keep the lifters planted on the cam, and big dual springs to keep the valves under control...every trick in the book.

Big $$ for just a few extra top-end HP which you'll give up at lower RPMs when you're trying to exit the corners.

And as AU-N-EGL mentioned, your corner exit speed is where you're starting from at the beginning of the straight...the car running 70MPH after the corner exit has a big advantage over the car running 65MPH.

AU N EGL

If you wish to rebuild your valve train every few months, then YES high lift can provided great results with the appropriate heads.

and rebuilding frequently.

drag race engines and high hp dyno kings are very very different then road race engines.

Reliability and Power are key.


The two areas we see engine failure on road course are oiling issues and valve train failure from high lift cams

AU N EGL

smallish cams also have greater / quicker throttle response vs bigger cams.

Out of the corner speeds and quick throttle response vs high end RPM hp.


for a 383 Race engine

Here is a possibility: 54-448-11 XER287HR
238/240 605/609 112+2
rpm 2800 to 7200

LSr lobe design

yooper

Speaking of old school, whats your spin on the GM ASA cam 88958770 both for standard cubes and the 383 motor.

The lower lift should help the valve train life, but is it too mild for road racing?

AU N EGL

IIRC the ASA cam is a dynamite cam for the LS1s stock cars.

GMPP ASA 226/236 525/525 110 2500-6500rpms

I would think there are better cams now especially for a 383

bsalie99

I can tell you that the Vengeance racing LS3 stage III cam really sucks for autocrossing. its specs are 231/243, .617/.624, 115+3.
It has a hard hit when you get into its powerband and that tends to be mid corner, upsetting the car, and tuning it to run right was a real bitch.
It does make good power and is right at home on the dragstrip

TriplBlk

I have an GM ASA cam if anyone wants one, totally slipped my mind lol

AU N EGL

Might have been too big of a cam for quick throttle response needed for autocross.

GettReal

Hey Keith, that is REALLY good power for your set up, I think mine currently has just over the 440 and thats with it being a stroker, mind you the torque is around 435-440 as well, which I like. I actually never cared about the numbers either and have only done 1 dyno in the last few years.

When is TrackMasters doing their next WGI days, by brother in law is addicted and now wants to go back to the Glen soon.

Tom, You just made me remember that I have that exact cam in my back up motor that has very few miles on it... I'm going to pull that one and use it. It was my favourite cam and made great power as well

kmagvette

Next Trackmasters is June 4->5. Let me know if you or any of the crew are going...been a while since I have seen you guys.

AU N EGL

VGLNTE1

a torqey one that comes on early, and easy on the valvetrain. you dont need a big cam to make peak HP, considering you arnt there nearly as much as when you really need it, coming off the corners. for a 383, i would do a 237/237 590 liift 112+4...something like that. Good midrange power for those cubes.

GettReal

Hey Keith, won't be able to make that one, we have 2 events here at Mosport June 1 and June 4th. We are looking for a couple events at WGI Mid and end of season though... Will look for postings and maybe see you there.

varkwso

Vengeance is about dynos and drag racing.

waddisme

I have the MS3 in my forged LS2. When I rebuilt my motor, I had someone else spec it out as I just didn't know. I have over 30 track days in the past 3 1/2 years. Zero issues. I did redo the heads last spring, so I am keeping with repl valve train every 2 years. Car makes great power with plenty of readily available torque. Generally, anyone I can't out drive, I can outrun. Needless to say, I out run a lot of people.

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