Ok IF the rumors are true i.e. LS2 heads will have 3 valves/cylinder and be fully reverse compatable with the LS1 engine, how do you think they would work with the current high HP cams out there like the LGM G5X-x series?

So far these cams will pull hard to current redlines. Rumors are also that these heads have been tested to 8K rpms. Would these heads give more low end hp/tq and pull higher at the top as well?

Interested in opinions.

 

This may be a dumb question; well maybe an unimformed question. Frankly, if one means by 'reverse compatible' with the LS1, I'd like to see how they are going to make the rocker set up work. Either they are running one big intake and two small (or visa versa). How are they going to accomplish that with a cam-in-block setup? I thought most motors with greater than 2 valves per cylinder are OHC units?

 

The 3rd valve is acctivated via a horizontal pushrod system.

 

One pushrod could work 2 valves. Maybe similar to this 4 valve 350 head.




Mike

 

I have a feeling the intake valves are going to be lower lift since there's 2 of them and because of their position. If that's the case, i think the lift on current high lift cams is gonna be too much. On the other hand, the rocker arms might be a lower ratio than the current 1.7:1 because the valves are closer to the pushrods and the rocker arms must be smaller. Hard to tell from looking at the picture.

 

I agree with P Mack that the intake side would need different numbers since there willbe two valves. And the designs I have seen have the same pushrod actuating both the valves. The lower valve is actuated by an arm as stated above.

 

I dont think the big cams will work well at all. It would let to much air in and not enough out (2 int & 1 ex. valve). The lift on the intake side will have to be decreased.

 

Initially, my understanding is the ls2 heads will still have just the two valves. I thought whenever "new" LS6 comes out that THEN the vavle arrangement would be 3 valves per cyinder,

 

The LS2's in testing in Austrailia only have 2 valve heads.

 

This is a true statement. The LS2 gains that additional power from a displacement increase and possible variable valve timing ability. The LS7 that debuts in the new Z06 will be the one that supposably has 3 valves.

Todd

 

Thanx for education! My only comment about the multi valve, single pushrod setup would be the huge potential wear factor on the cam/lifter/pushrod/rocker system. Twice the spring pressure, twice the geometry and associated force. Would this not also lower the potential redline?

But heck, what do I know?! If they build it, drop it into a factory ride with a warranty, then it must work!

 

I don't it'll be that much of a problem for two reasons:
1. Each intake valve is significantly smaller, so they'll be able to use less spring pressure on each spring. The total mass of the valves won't be twice the mass of an ls1 valve, so the spring pressure won't need to be twice as much either.

2. With less intake valve lift, they can get away with even less spring pressure to control valve float.

So i'm guessing there'll be more wear than on the ls1, but not twice as much. Maybe they'll use roller cam bearings to reduce wear . They'll probably take care of the redline by using good valvesprings from the factory, as opposed to the weak ls1 springs. JMO.

 

Here's a couple of pictures of the head that were posted a while back.

Gonna look like a big block with the valve covers to hide that stuff.

 

Pardon my ignorance: will these heads be 'reverse compatible' as is 'bolt-ons' for our present LS1 blocks?

 

There has been talk that they will be. They still only use two pushrods in the conventional spots so it's a possibility.

 

The 3 valve/4 valve type head is good to a point.They rev to unreal rpms,but our lower end can't handle the high rpm as much.

When I changed valve springs on my 96 CBR 900(4 valve)I did it by hand without a compressor.Very light spring pressure ,but reved to 14,000 rpm.

 

Doesnt that exhaust valve placement look a little weird? Looks like the pushed it to the side so they can fit another one in there.

 

Thats definatly an interesting look at those heads, that big bore aluminum block is sure to cause some changes for us as well.

 

If that's the case, there would seem to be some fitment clearance issues in the engine bay for the f-body. Plus, a new intake manifold will be another issue. Might bring manifold to hood/cowling issues as well.

I reckon time will tell.....

 

They'll probably fit in the next generation Fbody...whatever it might be.

BTW, the motor in those pics looks like a truck motor from the accessory layout and the threaded post on the water pump pulley for an engine driven fan. The fuel rail looks VERY similiar also.