2 vs 4 valve/cyl heads, their capabilities and the impact on tuning

[roguetrip]

With well ported heads and a cam which has better duration for a stroker would be awesome to see.

Looking at the LS7, looks like they just do lots of the performance basics, heavy stroke w/ supporting cam, big valves and high compression. There stroke is 4" compared to our 2.99" stroke, pretty crazy, I'm not even sure the rev range on a LS7 but sure it doesn't go much further than 7k.

I wonder if the 3.0 could even get up to a 4" stroke!

[Shadow24V]

heres a good link to info on the 24v SOHC motor/cams i have

Magna info

[kreel]

Quote:

Originally Posted by roguetrip With well ported heads and a cam which has better duration for a stroker would be awesome to see. Looking at the LS7, looks like they just do lots of the performance basics, heavy stroke w/ supporting cam, big valves and high compression. There stroke is 4" compared to our 2.99" stroke, pretty crazy, I'm not even sure the rev range on a LS7 but sure it doesn't go much further than 7k. I wonder if the 3.0 could even get up to a 4" stroke!

Redline is right at 7k IIRC. They make some sweet power right off idle all the way to redline too.

The billet stroker crank can take a 3.0L to 3.7L. Most of the displacement comes from a longer stroke but I don't know what the actual stroke is.

[Reaper1]

The reason the lifters can compress when we are handling them is due to no pressure being fed to them. Otherwise, they keep a constant pressure on the valve tip(hence their TRUE name: hydraulic lash adjuster). They should not squish much(if at all) while the engine is running. Their primary reasons for use are quiet operation and less wear. Solid lash adjusters can help the engine make more power due to them being lighter and keeping a tighter tolerance so the valve action stays in time better.

[c2xejk]

Quote:

Originally Posted by Reaper1 They should not squish much(if at all) while the engine is running. Their primary reasons for use are quiet operation and less wear. Solid lash adjusters can help the engine make more power due to them being lighter and keeping a tighter tolerance so the valve action stays in time better.

If solid lifters keep valve action in better time, then something has to be squishing in the hydraulic lifters... If hydraulic lifters do not squish at all, then they should keep valves in perfect time.

So are you saying hydraulic lifters randomly squish? dynamically squish? Squish a little? ???

[Shadow24V]

i always thought hydraulic lash adjusters were there to slowly take up wear slack to keep valve lash down to a minimum. solid adjusted have to be adjusted every X miles

[roguetrip]

Quote:

Originally Posted by c2xejk If solid lifters keep valve action in better time, then something has to be squishing in the hydraulic lifters... If hydraulic lifters do not squish at all, then they should keep valves in perfect time. So are you saying hydraulic lifters randomly squish? dynamically squish? Squish a little? ???

At high RPMs they start to collapse which makes valve float, the DOHC TT's have the issue with the lifters around 9k when they start to collapse.

[Reaper1]

The collapse happens due to aeration of the oil. When air gets in the oil, then it can compress.

In other cases too much pressure can be held in the adjuster and it will not allow the valve to close.

Their job is to keep zero clearance on the valve at all times. The only reason they can move is for when the valve is closed(when the oil hole is open). Any other time they are supposed to act as a solid lifter(oil hole is closed).

[Shadow24V]

on club3g.com there seems to be a general consensus that power drops off after 5500 due to valve float/cam profile.

im hoping to get some good cams this summer and see what i can do with it...

[c2xejk]

Quote:

Originally Posted by glhman You're a few years behind. The LS2's came out in 2005 with 400 HP with 6.0L, where the 7.0L LS7 is in the new Z06 making 505 HP, and the ZR1 is powered by an 6.2L LS9 making ~620 HP (supercharged)

So how much did the valve size change?

[roguetrip]

Quote:

Originally Posted by c2xejk So how much did the valve size change?

The LS1/LS2/LS6 all used the same valve diameter while the LS7 went a touch bigger.

here are a few quick tidbits on the LS engines.
Camaro Tech: Chevy LS series engines: LS1, LS2, LS6, LS7, LSX

[SpeedyEd]

Hydraulic lifters allow quiet operation of the valve train while compensating for valve stem growth (heat expansion). Bleed down is a low speed (more time) occurrence, pump-up happens at high RPM with valve float. If the valve springs can't control valve motion the lifter fills up to take up the clearance, causing the valve to stay open.
Setting the lifter pre-load to zero limits pump-up but can allow clatter in a cold engine (like solid lifters).
Most solid lifter cams have more clearance on the exhaust lobes to compensate for the higher heat.
Hope that helps
SpeedyEd

[thejoker1290]

what would i have to do and get to put the 24 valve heads on my car???

[87turbodance]

The heads will physically bolt to 12V 3.0 bottom end but you will have to be creative with the timing belt setup. Or you can swap an entire 24V motor into your car with custom mounts and a remote oil filter. Either setup will require custom fuel management. Since there are no custom cals for the 3.0 computers you will need something like: www.MSEFI.com or some sort of Trimcal

[Hemi417]

So can I take the 24valve cylinder heads off of a chrysler3.5 and put it on a mitsu 3.0 or swap the whole motor to the mitsu tranny? mine is in a montero frame with truck body so I got room for anything