VH Cams thread.

[elwesso]

OK, there has been some talk of cams on the VH, but i wanted to start a new topic about this, sort of for the exhaustive one stop for all info...

Basically this is the kind of deal to talk about modifying valves, valve springs, and actual camshafts... Anything...

I know that defrag has done a lot about valve springs from other (domestic) motors to see what works.. We also know that the SR20DET from the GTiR inner valve springs seem to work on the VH...

Lets talk about cam grinds as well. It seems that most agree that the stock cams are about ideal for boost.. What about for N/A...? What can be done to the cams, and what kind of power could we expect to see....? what would be the downsides.....?

[defrag010]

The stock VH cams don't even produce .400" valve lift. That's pretty puny in the grand scheme of things - which is why the VH probably runs so smooth.I'm not sure on the piston to valve clearance with stock cams because I haven't done that much extensive work on the longblock, but I do know that the stock valvesprings are entering coilbind even at the stock lift, so with any kind of cam upgrade at all you will need to get new springs to be able to hold the lift. If we can open these motors up to about .450-.500 lift, then there will be TONS of gain. Even at stock duration, more lift would yield a ton more lowend torque and with true headers, a good intake, and a perfect tune 300hp should be a piece of cake. Look at the 4.6 DOHC ford motors -- they make 300 horsepower with just a good tune, and they have cam lift in the lower .400's.

If upgrading valvesprings isn't on your menu, then you can still get alot of gains from a cam grind that has a slightly longer advertised duration along with a seat duration with more change than the advertised duration. Long advertised durations with short seat durations will cause compression bleed, which is why large cams require high compression - this won't be good for our motors. Pay attention to the seat duration more than the advertised, and get as much seat duration as you can without too much advertised.

example: with a stock cam with 248 degrees advertised and 195 @ .050" seat duration, a new cam with for example 262 degrees advertised and maybe 230 @ .050". A shift up in seat duration = a shift up in powerband. I don't knwo the stock specs right now, but I would not go more than 30 degrees more seat duration than stock if you want to still make power at a low rpm. 30 degrees more seat duration will give the motor a chance to actually make power up to 7300 rpm.

Lastly, overlap is needed for a n/a motor, but too much will hurt you. The more compression you have, the more overlap will benefit to an extent. On a ~10:1 4valve motor, you would probably see good scavenging and get a good gain at around maybe 10 degrees of overlap.

The problem with the VH cams is that there are no blanks made by comp and crane (I've already called them about it). That means we are forced with regrinds. Regrinds are good and all, but you have to adjust the rest of your valvetrain to suit them. Depending on how much they take off of the base circle when they do the grind, you will need to alter your valve height and shim your lifters up. If they take .13" off of the base circle, then you will need to raise your valve height by .13" and shim your lifters by .13" to keep your rocker geometry on track and the tip of the rocker on top of the valve.

Cliff notes:-You will need new valvesprings if you want cams with more lift-30 degrees more seat duration, and 10 degrees overlap for a street motor-.450-.500 lift (PVC permitting)-valve train compensation for lower base circle of regrind-300hp will be a snap with a .500 lift cam, true headers, good intake, and a perfect tune.

[Ezekial]

great post!!

take note ... tighe cams in AUS can hard face factory cams to retain existing base circle.

Rough Prices

Regrind $100 AUD / camshaftHard Face & Grind $200 AUD / camshaftBillet $400 AUD / camshaft

[elwesso]

Thanks Defrag..

First off, that is a pretty technical post, im gonna try and see if I can follow.....

In order ot do any real good cam work, we need to upgrade the valve springs... not a big deal since we can use the GTiR springs or whatever spring combo you have... Valve springs shouldnt be a big deal...

assuming we have enough clearance, we would want to make lift on the intake cam .450-.500"... I assume we leave the exhaust cam stock, or do we make it with that lift as well... we also want aout 30* more duration,

How would this effect things like idle and overall smoothness...? Woulldnt you think the intake would be pretty good as it is, or were you just referring to a CAI or something like that..... The stock TB is good to big HP.... Would this cam setup work well with a boosted setup... I assume with boost you would need even stiffer valve springs...

Also, how will this work with the stock ECU, or stockish ECU? Will it need to be changed in order to work properly??

IM sorry for all the dumb questions, but this intrigues me... It seems possible to make 350+ish HP on a N/A and fairly stock motor (stock short block and stock intake manifold)...

[Mettler]

Elwesso it should work ok on the stock computer, all it'll do would be increase the airflow into the engine per combustion cycle, something which the AFM would pick up and automatically make provision for with the injectors.

You may want to change the VVT timing, but that's about the only ECU adjustment I'd be concerned with. (Well, that and the incredibly rich mixture the factory ECU has been programmed to run.)

[Ezekial]

In order ot do any real good cam work, we need to upgrade the valve springs... not a big deal since we can use the GTiR springs or whatever spring combo you have... Valve springs shouldnt be a big deal...

The GTiR inners is basically a VERY CHEAP method of giving a little more pressure and some dampening at the same time whilst retaining factory camshaft grinds!

I would love to check out some off the shelf JUN GTiR replacement items and check to see if they can be used. I cant see why not but thats more expense. Also "performancesprings" in AUS sell uprated springs cheap

Quote »assuming we have enough clearance, we would want to make lift on the intake cam .450-.500"... I assume we leave the exhaust cam stock, or do we make it with that lift as well... we also want aout 30* more duration, [/quote]Same lift on both. What defrag was getting at was if you are going to increase the duration, increase seat time not advertised ... ie. try not to push the closing angle out too far or compression leaves you. Not so bad for turbocharged applications but for NA ... not good at all. AS IS they are already late closing. The VVT switching it 20 degrees earlier is really all that saves it

Quote »How would this effect things like idle and overall smoothness...? Woulldnt you think the intake would be pretty good as it is, or were you just referring to a CAI or something like that..... The stock TB is good to big HP....[/quote]Would affect idle noticably if you pushing duration out to 260ish and 11ish mm lift Quote »Would this cam setup work well with a boosted setup... I assume with boost you would need even stiffer valve springs...[/quote]For boosted you could afford to lose some comp as above ... so you wouldnt have to worry as much about seat duration vs open/advertised duration

Once again ... great post defrag!

[defrag010]

In order ot do any real good cam work, we need to upgrade the valve springs... not a big deal since we can use the GTiR springs or whatever spring combo you have... Valve springs shouldnt be a big deal...

gtir inner springs will be okay for a cam with stock lift but more duration, but for a cam with .450-.500 l ift you will need to get springs that will allow more lift because the stock VH springs have a max lift capability of just under .400" lift before they reach solid height.

Quote »assuming we have enough clearance, we would want to make lift on the intake cam .450-.500"... I assume we leave the exhaust cam stock, or do we make it with that lift as well... we also want aout 30* more duration, [/quote]both the intake and exhaust would be ideal, but they don't need to be the same. The exhaust cam for a n/a app usually has a longer duration and lift than the intake side. So, the more aggressive cam in a n/a application would need to be the exhaust cam.

Quote »How would this effect things like idle and overall smoothness...? Woulldnt you think the intake would be pretty good as it is, or were you just referring to a CAI or something like that..... The stock TB is good to big HP....[/quote]I'd say the stock intake manifold and TB will work as good as any, because there are no major flow restrictions and it's an overall good long resonance design. The only thing I can think of that would help on the intake manifold is for it to have a larger plenum. Usually, on a n/a engine you want the plenum volume to be 100% or 2x larger than the engine displacement. For intake, I would look into just getting a nice 90mm short ram tube with the maf on the end.

A cam with more overlap and more lift will be a little bit more rough, but it won't sound like a bigass bigblock race car. A mild cam like we're talking about will be enough to where you shouldn't feel or hear that much lope, but it won't be as smooth. It will be rough, but still run good and give decent vacuum. It should still run on the stock ECU since it's maf based. map based ecu's have a harder tine controlling fuel because the low vacuum signal makes the ecu think the engine is under load. Quote »Would this cam setup work well with a boosted setup... I assume with boost you would need even stiffer valve springs...[/quote]What we're talking about is strictly a n/a setup. For a boosted setup, you don't want any overlap at all and you want to match the cam duration and powerband with your turbo compressor map.

Quote »Also, how will this work with the stock ECU, or stockish ECU? Will it need to be changed in order to work properly??[/quote]It will run okay as-is because the ecu is maf based. It will need to be tuned to work properly and get the most power for sure but it will run with no modifications.

Quote »IM sorry for all the dumb questions, but this intrigues me... It seems possible to make 350+ish HP on a N/A and fairly stock motor (stock short block and stock intake manifold)...[/quote]I don't mind at all, I love spreading knowledge and edjumukating people.I bet with a nice set of healthy cams with the right valvetrain, a true longtube header system, an intake manifold with a 8L plenum, and a good ECU tune 325hp to the wheels with a flat powerband all the way up to 7500rpm will be a piece of cake.
Modified by defrag010 at 10:02 PM 7/10/2006

[slownslurious]

Lets talk about boost cams... ANYTHING out there? what cam setup would you recommend?

[Mettler]

Why does everyone mention/discuss the sound of the engine being rough at idle when you have a cam with heaps of lift ?

AFAIK that's a desirable thing... nothing sounds tougher than a lumpy V8 idle! The lumpier the better I say.

[slownslurious]

yeah I defintely don't mind a hard sounding engine... but people are saying stock isn't bad for boost so I may not need it.