I'll try and keep this brief so as not to bore everyone to tears...

I've been reading this forum and the excellent knowledge shared by UDHarold and others and it has made me think that maybe I'm leaving power on the table on my setup... The new line of voodoo cams look very interesting, especially the part about lowering peak acceleration at the seat.

Quick specs on my setup:

454 BBC
3400 lbs vehicle weight
Edelbrock 'roval' aluminum heads
9.5:1 CR
1 7/8" full length headers, dual 2.5" exhaust.
Tremec 5-speed manual
3.08 rear gears
Programable EFI (port injection)


Application:

Daily driver in fairly heavy traffic. Needs to idle smooth @ 850 rpm. Needs to pull from 1000 rpm to about 6000 rpm. Want torque peak around 3500 rpm and power peak at 5500-5600 with 6000 rpm shift.

I'm currently running a comp cams custom grind: Hydraulic roller, 224/230 @050. 0.573/0.585 lift with 1.72:1 rockers. Lobe ID 3110/3112. Supposed to be a 114 LSA but exhaust is early and it measures 115.25 LSA.

Current cam idles with 19" of vacuum @850 rpm.

On a dynojet it made 392 rwhp and 440 rwtq with a torker II and holley 750 carb. I guess slightly more now as the EFI intake is better.

So I'd like to stay with a hydraulic roller. Current power peak is at 5300 rpm and I wouldn't mind moving that up to 5600 rpm. It needs to have long life (100k or more miles).

So is there a Voodoo series hydroller that will make more power without giving up drivability? Any other cam that would be a step up?

Hydraulic roller info will not be available until after Jan 1st. I get in trouble for saying too much too soon..... We are waiting for dyno results, but I am expecting similar results as the VooDoo hydraulics.

UDHarold

Harold: Thanks for the reply. I'll sit back & relax until January and post again.

I have confidence that when the hydroller info is ready it will be impressive.

Markus

Hold on...just a minute....I can't believe my eyes....

Is that Zwede looking for a cam???? :)

YES there is a better cam for you...and it's bigger!!!

Looks like we have a new inhabitant of the "Dark Side"!!!

At least I can dream!


JIM

Jim.... imagine finding YOU here! Note that I didn't ask for a BIGGER cam... just BETTER.

BTW, didn't you go down to some weenie cam yourself? Only 260 @050 or something tiny like that?

Markus

Yeah I wussed out......266/272@.050 .731 lift even out to a smooth wussy 112 LSA!

Jeez...what's wrong with me?

And I have to admit..not sure what all did it, but with new cam, bigger headers, new trans I picked up 7 mph in the 1/4! And the 1/8th mile speed was almost increased as much too!

Not as much killer top end overall, but much more midrange. Picked up from 105 mph 1/8th to 112 and from 133 to 139.96mph in 1/4.

It's all good!

It just did my heart good to see you looking around!

How 'bout some new heads too?


JIM

It starts so innocently. A "better" cam at a few hundred higher rpm. Then perhaps some heads. To really exploit the cam and heads, you could add a stroker kit -- nothing like a long arm for street duty. While you're at it, no harm in bumping compression another 0.5 - 1.0. But then you'll need even a bigger cam to keep peak HP rpm above 5500 w/ the added cubes. Now you need a header upgrade.

Resistance is futile....

Mark

must.... resist.... evil spirit... of.... performance...

... but a better cam would still be interesting. smile.gif

Ooooh, I can see them nasty, dreaded old, "more power, Scottie" bugs a-buzzin' around here in clouds, big-time!!

He, He!!

It's not a "lash cicle" anymore, it's a "horsepower circle"!!!

he, He!!!

Carry-on....

pdq67

It doesn't help that Zwede's buddy Nick has "fallen on" the wagon! His nice little street 540 with GM/Edelbrock heads has recently been treated to a new intake, a bigger carb, new headers, new cam and head porting....then if that wasn't enough....the heads came off a month or so later and he now has a set of AFR 357's from Mike (Wolfplace) and is working on another new cam idea!

You know, since Nick REALLY wants a 632,,,you might as well start dealing with him for his 540 shortblock!

Gotta be careful who you hang out with!


JIM

Speaking of Nick, I just came back from his place. Those high dollar heads and guideplates and none of the rockers sit right on the valves. We fixed one cylinder... had to cut the guideplate apart and weld it. 7 to go. I kept asking him what was wrong with his old heads and he muttered something I think was meant to be insulting...

Yeah, I heard..that's weird.....you wouldn't expect to have that much trouble...but it happens sometimes. I'm looking for some other guideplates for him......

But when it all gets together, it ought to be fun! I never got a chance to ride in it after the head porting and cam change....or for that matter the intake or carb change...jeez..I'm way behind!

Now if we can just get a "real" cam in it and some bigger exhaust...it's gonna fly!

Sure you don't need a 540???


JIM

Nick just borrowed a spare original GM guideplate I had laying around and found that it lines up the rockers much better than the AFR ones. He said the exhaust was still off a little but the intake is perfect. The same guideplate lines up both rockers perfectly on my Edelbrock heads. Looks like AFR does something funky with the exhaust valves.

As for getting a 'real' cam... you know what amazes me is what GM is doing these days with tiny cams. The LS1 makes 350 hp and has less than 200 degrees intake duration (@050). It also revs to 6 grand. That just blows me away!

Originally posted by zwede:
Nick just borrowed a spare original GM guideplate I had laying around and found that it lines up the rockers much better than the AFR ones. He said the exhaust was still off a little but the intake is perfect. The same guideplate lines up both rockers perfectly on my Edelbrock heads. Looks like AFR does something funky with the exhaust valves.

As for getting a 'real' cam... you know what amazes me is what GM is doing these days with tiny cams. The LS1 makes 350 hp and has less than 200 degrees intake duration (@050). It also revs to 6 grand. That just blows me away! =
Markus,
Tell Nick to be sure to call & let Tony know what he found on the guide plates & I will try to remember to call him too.
He is very receptive to feedback, especially regarding any problems folks are having.
& you are right, the exhaust valve is rolled 2 degrees, ;)

Hi Jim, graemlins/waving.gif

Zwede,

That is an interesting observation and shows us the practicality of cam timing. The shorter cam will peak lower but still have usefull power at rpm above peak power. The difference is trying to set up a motor to hit peak power through the traps for drag racing is somewhat different than other types of performance, say street or road racing where you want the power band to be a little lower and broader. If this were a sports car forum, the discussion would be different, but hey, Chevelles and their enthusiasts are drag racers by nature.

It real trouble to run such wide LSA's with such little static compression, imho. Make's ithard to make great torque, unless its a huge inch deal. That's the big glaring issue I see. At risk of being reductionist and using DCR as a basis for talking about cylinder pressure, you must be below 7:1. No torque made there. Your same cam on a 110 would be a HUGE improvement IMH amatuer O.

Hmmm... wouldn't it be the opposite? Wider LSA reduces overlap and thus builds more DCR? GM runs 117 dgr LSA in the LS1's and they seem to be running pretty well.

Mine dynoed 440 ft-lbs at the wheels @ 3800 rpm. I guess that translates to about 550 ft-lbs at the flywheel.

Originally posted by GRN69CHV:
Zwede,

That is an interesting observation and shows us the practicality of cam timing. The shorter cam will peak lower but still have usefull power at rpm above peak power. The difference is trying to set up a motor to hit peak power through the traps for drag racing is somewhat different than other types of performance, say street or road racing where you want the power band to be a little lower and broader. If this were a sports car forum, the discussion would be different, but hey, Chevelles and their enthusiasts are drag racers by nature. Yeah, for an all out drag car I agree. Plenty of duration on a tight LSA usually runs best. But I'd think there are a lot of people on here that mostly drive on the street and go to the track every now and then.

What would be killer for us would be a cam that has the drivability of a modest cam, but acts bigger on the track. Kind of what GM seems to have achieved on the LT1's/LS1's. Driving these cars you wouldn't belive the cams are only 200 dgr. I'd be thrilled if I could find a cam that drives like a 220 dgr cam but runs like a 240 dgr cam on the track.

I think a big key is cylinder head efficiency. The worse the heads, the bigger the cam you need to make the same upper HP, but lose bottom end power. Like stock eliminator engines, you need a lot of duration because a lot of the heads don't flow great.

We dynoed a stock eliminator LS1, for those familiar with the rules, stock engine except you can run more duration. That thing didn't fall off at 7500+ RPM. I think they could have went smaller on the duration. On the opposite side a stock elimiator TPI engine will fall on its face around 5500 RPM no matter what the cam.

Heads and intake make a big difference.

Personally Markus I would consider tightening up the LSA a bit to 112 possibly. You should still have plenty of vacuum. 20 is too much! smile.gif

Hey Doug, I don't know... I like the wide powerband of the 114 (actually 115) LSA. It still has a noticable torque peak at 3800. It will be interesting to see what UDHarold cooks up with his hydrollers.

Gene,
Big engines do not need tight lobes to make torque & they tend to like cam.
You have to be able to fill the cylinder or you ain't gonna make power.
If all you use is "DCR" (I won't expand on my opinions any further here :D )on a lower compression big inch engine you will build a nice torque makin slug that will be great for pulling your motorhome up a hill.
Also, the better the head on the same engine the less cam you will need to fill it under the same conditions.
It depends on where you want to run the engine.

As for torque, do not believe you can't make torque with pretty long cams at under 10.0 static.
If a 489 with 9.8 & a 254 intake lobe cam on a 111 separation can make over 500 lbs ft under 2900 then I don't think a 540 is going to have a problem with torque production :D

Markus,
Cylinder cranking pressure is more with the tight lobe centers because you are normally closing the intake sooner & this is where you start making cylinder pressure.
Overlap has almost nothing to do with cylinder pressure at low RPM's, it is on the opposite side or about 360 crank degrees from where you make compression.
It becomes very important when you get "on the cam" or around peak torque when the engine gets efficient when wave tuning starts having an effect on cylinder filling but for the "DCR" as used here it means almost nothing. ;)

Mike: Aah, I see what you're saying. LSA affects idle quality, emissions & fuel consumption, but DCR is determined mostly by how far after BDC the intake closes and not the overlap event. Makes sense. This then also explains why advancing the cam will build more low end torque. Intake closes earlier = higher cylinder pressure.

Thinking some more on this, it would then seem that going to a wider LSA (with same duration) would allow the engine to run on less octane?

Yeah, tighter LSA builds cylinder pressure...just like advancing cam. Same effect...intake is *usually" moved forward which closes intake earlier. What's often confusing is that cams with tighter LSA's have more overlap also if duration stays the same. So often a tight LSA cam gets blamed for all the poor manners of the increased overlap. You will often see larger cams have increased LSA to maintain reasonable overlap. That's why you see Pro Stock cams out to the 118-120*+ LSA range. Tight LSA is a nice way to "wake up" a mild cam...look at the Musclecar stuff that Comp etc do. Check out the mild flat tappets for roundy pounder stuff. Pretty mild durations, but fast ramps on a tight LSA....like Donny has in that 327..it just flat rocks!

My last 272/278 on a 110 LSA was pretty choppy on the street (as you know Marcus..you followed me on the highway and got to smell it!) but it actually had pretty decent driveability..better than the 266/276 on a 110 LSA flat tappet I tried this last summer.

The first cam in the 540 was a 262/273 on a 112 that was downright wussy sounding...like a big 'ole truck motor...had a lope...but nothing radical. It would lug down to 1200 rpm in high gear with no issues. It peaked HP around 6200-6300. The 272/278 peaked at 7400 rpm. I'm in a happy medium area right now with the 266/272 on a 112.

I think there is some real interesting stuff that occurs when you look at each event of the 4 strokes separately, figure in rod ratio and rate of change in cylinder volume etc to help pick a cam. I just wish I had ways to measure everything I'm curious about like the NASCAR/Formula 1 guys can!

JIM