RFE-57

Anyone have any updates?

mistermog

would be nice if we hear itll happen in the next 2 weeks, im taking my heads off to send out somewhere for SOMETHING...

Corvette0096

jwmgr8

In the world of Engineering it would seem to me that you need to define the why, what and how of the tests. Your list looks like the what and I'm sure you'll define the how when you run the tests, but what is the why?
I know a lot of people would like to see the comparison of several setups but what is driving you to run the tests? plus before the tests are run what might the results tell us? is it possible to define poor, good and best?

Random84

(Captain Obvious)
Is that a rhetorical question, Caller?
(/Captain Obvious)

Katech_Zach

The why is explained in post #24: http://forums.corvetteforum.com/1582785923-post24.html

To understand what we are looking for, a good place to start is this article: http://www.gmhightechperformance.com...e/viewall.html

Mark2009

Bumping this since several expressed interested (vertC6, myself, Mookster, Bad Ax, spinkick, RFE-57, atljar, and Michael D). To directly answer Jason's question (at least from my perspective):

1. Stock cam/springs, stock valves
1a. Above w/Yella Terra 1.8
2. Stock cam/springs, solid stainless exhaust valve
--- Since the above is expected to fail, no additional test.
3. Stock cam/dual springs, solid stainless exhaust valve
3a. Above w/Yella Terra 1.8
4. Torquer cam/PSI springs, stock valves (already tested long ago, but we will baseline again)
4a. Above w/Yella Terra 1.8 (assuming stock springs will not carry the weight in 1a above).
5. Torquer cam/PSI springs, solid stainless exhaust valves
--- Since the above is expected to fail, no additional test.
6. Torquer cam/dual springs, solid stainless exhaust valves.
6a. Above w/Yella Terra 1.8
7. Torquer cam/PSI springs, Ti exhaust valve
--- Test only if all YT combinations above w/OEM valve fail.

Depending on how things shake out, that looks like about 4 additional tests.

My main concern, while acknowledging that the aluminum rocker may not be the best choice in the long run (but it is the most cost-efficient in the short run), are scattered industry reports that a roller tipped rocker will reduce -- or at least equalize -- side load on the valve guide compared to the OEM style rocker, and do have a slight range of adjustment to center the wipe pattern on the valve stem tip (an unsolvable problem we are seeing with some OEM rockers). Given the problems the OEM LS7 heads have with valve guides, and given that we don't know exactly what is causing those problems, any help at all -- such as a reduction in side load or a centering of the wipe -- seems to be a worthwhile pursuit.
.

vertC6

That's pretty much what I had in mind.

'06 Quicksilver Z06

Good.

Probably better to not get sidetracked on all of the other wild suggestions, and get to the bottom of what it is you are searching for.

Good luck and looking forward to your results.

jwmgr8

Obviously you should be thanked for your efforts and all the BS you sort through to help all of us better understand our engines.
I'm still curious do you test to failure? or are there specific numbers you'll record that helps define "safe"?
I'm just glad we have some one like you sorting through the fog of data. I'm sure you've seen 1000's of LS7's over the years and you have a much better understanding of the dynamics of this engine than 99.9% of the people on the forum
good luck

Bad_AX

The only thing that could make this test better would be some video to post on Youtube at the conclusion. There is some very interesting stuff out there, but none specific to our LS7 engines.

This one shows some of the effects of valve float in an RPM range close to the LS7.

Here's another clip showing a multi-spring set up at 7000 RPM that looks pretty stable.

This one is just off the charts. OHC BMW at 14K RPM. Of course F1 engines have exceeded 20K RPM but are now regulated to 17 or 18K.

A good article comparing NASCAR Cup engines to F1. The Good Ol Boys are smarter than you might think. Includes some commentary on valve train components.
http://www.epi-eng.com/piston_engine..._cup_to_f1.htm

A very good article on valve spring technology, the Spintron, and the high costs of R&D.
http://www.popularmechanics.com/cars...nascar-6643778

Mark2009

Good stuff, thanks for posting

As to the Good Ol Boys, I recall that decades ago Smokey Yunick was into ceramics (engine parts and even engines). That was outer space stuff at the time. Maybe still is . . . .

http://www.hotrod.com/techarticles/e...e/viewall.html

Rock36

Some video might be cool to go along with the results if possible.

I'd also point out that what is most relevant to this proposed Katech test on the LS7 is the valve bounce. The first video shows that at about the 3:12 mark pretty well.

If one reads the original test Katech conducted with PSI 1511 springs and the 98g inconel valve, the limiting factor was the valve bounce much more than the valve float.

Bad_AX

Gents,

Here's another good article that I've had saved for a while. A good discussion on the progression of valve trains in OHV engines.
http://www.chevyhiperformance.com/te...m/viewall.html

This video features the C6R 5.5 liter race engine. The valve train is clearly visible about 1.30 minutes in. The rockers appear to be Jesel aluminum. Does anyone know if the Jesel rockers are used primarily for reliability or mechanical friction reduction? Any information on how fast these engines spin?

Our LS7s are running pretty large valves, and making them live at 7K RPM with mass production components (i.e. cheapest possible) is no small accomplishment. I would love it if the LS7 survived another generation of development, and I would have paid up to buy another one with higher spec components. Further development of the LS7 is now up to us and the aftermarket. Again, I applaud Katech for offer to do this testing.

Katech_Zach

We are not doing durability or destructive testing. Only dynamics. Safe limits will be defined in our report.

mistermog

any eta?

Katech_Zach

Sorry, no.

hoefi

Just like the guide wear report. No ETA either.

Katech_Zach

I posted about the guide wear report. Once GM made the announcement it kind of made it irrelevant. The report was just a collection of measurements that's been duplicated numerous times on this forum.

hoefi

You did??? Where and when???

Just measurements, and no possible cause(s)? I did say "possible" cause, not "definite" cause.