Thoughts on compression/build

[cuisinartvette]

Let me pick your collective brains on a build...

First off Ive "heard" (yeah, I know...) that the LT5 is not a true 11:1 motor, is really closer to 10:1. NOW-If thats the case.....

-Options
1) Mill heads
2)Custom piston
3)What are the stock CCs on these?
4)Would add a slight bit of cam timing to take advantage of porting. Not 100% on this but heavily leaning towards it. Spring pressures may only increase a slight bit so longevity shouldnt be a problem.
5)Longer/lighter rods....
6)Wont be stroked

Now, for a real zinger....

How difficult would it be to create a solid type lifter, how would that work in terms to adjustment, lash ramps, etc??? Dont Porsche and Ferarri use somethign like this?

Kind of know the direction I want to go, just wanted some input..It never ends.
I promise Im sober posting this

[jonszr1]

the thing with trying to increase compression , if the knock sensor is activated now on premium pump gas wouldn't it defeat the reason for increasing comp? what if you actually thought of increasing the cc by 1or2 in matching all the combustion chambers . you might be able to put more total in instead of what corey did with mine 24.5 total down from factory 27-28. lighter rods ok but longer means shorter skirts. which is great on women but sucks on pistons . rod stroke ratio in outr engines not the greatest stk. Cams really dont seem to mke more power unless you put a 4in piston in it to unshroud the valves. cams seem to do alot for the 402-415 and unles you just want the lope , most say cams arent worth it . pete has trid all kinds of cam in his totally ported 350 with out making any more power. thats what ive heard hope it helps. get headers and port your stuff first just might like her that way. i know i do mine

[A26B]

Originally Posted by cuisinartvette

Let me pick your collective brains on a build...
Now, for a real zinger....

How difficult would it be to create a solid type lifter, how would that work in terms to adjustment, lash ramps, etc??? Dont Porsche and Ferarri use somethign like this?

Kind of know the direction I want to go, just wanted some input..It never ends.
I promise Im sober posting this

Solid lifters with required lash would wreak havoc with the knock sensor to the extent you would never be able to open the secondaries. Even if you removed the secondary butterflys, it would not go into open loop with the high knock count being registered by the solid lifters.

Not sure why you would want solids as the Lt5 is good for 8 grand anyway.

[cuisinartvette]

Just thinking out loud, so to speak . These do rev well, just love the sound and feel that a solid lifter motor has. No bleed down from oil thinning out when it get s hot...all the lift and duration 100% of the time. These (LT5) lifters do run on the same principle as a typicl hydraulic lifter would, no?

[Aurora40]

The higher compression and lighter rods is I believe what Callaway and Lingenfelter do on their 350 builds. Though I thought they raised compression via a piston change, not longer rods. But I'm no engine builder by a long shot.

I always think it's bizarre that there can't be improvements made with cams, but I guess even with stock cams, a little porting puts the power peak practically at 7,000 rpm anyway. So maybe the cams are already pretty aggressive. In my head it seems like if the primary lobes were the same as the secondary ones, you'd really make power then, but maybe there's some kind of symbiosis going on between them. What the hell do I know anyway...

Edit: Also, if you're gonna go all outside the box with solid lifters, etc, there might be more to be had going to a flat plane crank instead? It might also be a little easier to do in terms of supporting things that have to be done. But maybe not as the firing order would change.

[Jagdpanzer]

I would think twice about solid lifters if you plan to run this engine much. Setting the valve lash with shims as a real bitch on a DOHC engine with plane bucket style cam followers like the LT5 has. For the those who have been around engines for awhile high rpm hydraulic lifters are a gift from the engine gods.

[FU]

Use the KISS theory. Just go with a good top end port and cam timing. They are THE package for the ZR1. Don't try to reinvent the wheel here, It's been tried and true.

[QB93Z]

When I was talking with Marc Haibeck last weekend at Carlisle, he pointed out that the ZR-1 is essentially an engine with two different cams. In normal power, there is a civilized, smooth performing, "low-end" cam. When the secondaries kick in, the engine characteristics are dominated by a hotter cam. He said that it is one of the ways the designers got such a broad useful power band out of the LT5.

This might explain why there is not much improvement seen by swapping out cams.

Jim

[Aurora40]

Originally Posted by QB93Z

When the secondaries kick in, the engine characteristics are dominated by a hotter cam.

But it's only controlling one of two sets of valves. That's why I'd think if both cams had that profile, the max power would be improved, though I'd think low throttle driveability would suffer. But I guess that's not the case as people don't seem to gain much with cams on a 350.

[QB93Z]

Not exactly related to the cam discussion, but interesting, Marc also said that the combustion chamber flow was a swirl in normal power operation with only one valve flowing. The swirl was very effective for low power operation and emissions. But at full power operation, the combustion chamber flow was different with two valves flowing and was better for high power. Once again showing the genius of the LT5.

Jim