horsepower

we did this testing all in one day, all on the same engine. The only thing changed was the rockers (and the pushrods for the jesels). This is engine dyno testing. This is the .500 ls1 cam. The gains are a little higher yet on the new ls1/ls6's too.

RAMBIRD2002

I've heard lately that SLP is going to be selling the Yella Terra's, is there any truth to this?

427ZO6

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by RAMBIRD2002:
<strong> I've heard lately that SLP is going to be selling the Yella Terra's, is there any truth to this? </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">What you heard is correct. They ordered 500 sets. That is not a misprint

DanZ28

iTrader: (5)

WOW! That is an extremely large HP loss on the upper RPM from YT and Jessel. Can those possibly be flexing that much and why wouldn't they flex at lower RPM as well? I mean there is a pretty good drop in just a 100 RPM increment, 10+HP..

Dan

horsepower

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by 427ZO6:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by RAMBIRD2002:
<strong> I've heard lately that SLP is going to be selling the Yella Terra's, is there any truth to this? </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">What you heard is correct. They ordered 500 sets. That is not a misprint </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">??? no we didn't. SLP will be selling SLP 1.85s.

Raging Motorsports

Here's what I don't get then. If the Jesel rockers just drop dead in the water after 5800rpm why wouldn't ONYXSS's 427 with the Jesels fall off at 5800rpm? His graph clearly pulls up to 6800rpm. Also I think Jesel uses the same material as the non adjustable as they do the adjustable rockers and they rev up and over 8000rpm without this problem.

I really would like to see a better comparision of rockers other than this graph posted here.

horsepower

There is more to it than flex alone; this is a near stock engine (that is all you should consider our test for), possible flow separation, unknown dynamics, valvetrain geometry (stock and SLP are nearly identical - all alum. rockers will have different geometry by design) hydraulic lifters, spring and retainer selection, etc, etc.


As an update - The 'flex issue' has since been negated by the manufacturer (YT will be posting a detailed response, as the expert on the subject). Since the numbers at high RPM are questionable, we plan to re-test with various aftermarket valve spring configurations. Perhaps unhappy dynamics in the valve springs (valve float, bounce, etc) could be the culprit. I will re-post new results when completed.

Additionally:
I have received Spintron testing results back from Comp Cams - They noted the following:

"The SLP Rocker was added to the test engine and gave us .030" more lift without creating more bounce. The SLP rocker has less bounce @ 6100-6400 RPM over the stock set-up. The Comp Cams 26918 spring was added to the LS1 with SLP rocker. The Comp Cams 26918 spring gave the LS1/SLP rocker combination smoother loft characteristics while maintaining minimal bounce off the seat. The addition of the 26918 spring will give the combination of durability and performance we are looking for."

<small>[ February 27, 2003, 07:27 AM: Message edited by: horsepower ]</small>

1999Daytona500PaceCar

iTrader: (2)

Actually, the comparison does exactly what it is meant to do. It shows that by a hair, the 1.9's reach the highest peaks, followed by the 1.85's, on down (which would be expected) - BUT but it more importantly indicates that the SLP rockers do not fall off nearly as much as the rest do as the RPM's climb off to 6000 and above - as the SLP's must not incur as much flex.

StevieZ

iTrader: (3)

Don't believe everything someone tells you! I was told "no problem on a 98" Well I had to do 2 hrs of grinding the valve covers to make them work. I just swapped heads yesterday and it looks like I have to "attend" to them again as they are hitting the top of the cover now.

Phate

iTrader: (2)

I agree, I had to grind the hell out of my stock 98' valve covers...both on the perimiter of the valve cover and on the top.

I had to take A LOT of material off of the top of the covers.

Scott

JeffJeff

Both Yella Terra support and Raging motorsports told me they would clear the '97-'98 valve covers. They were wrong.

I had to grind around all the bolts on the intake side significantly to get them to clear. It was a lot of work. Once that was done, the rockers were hitting the top of the valve cover. I ended up going back to the stock rockers.

Nasty N8

iTrader: (33)

We are running a GP on these til the end of the month for $445.99.

Nate

CAT3

iTrader: (9)

JeffJeff, you still got them, if so they for sale?

WS6snake-eater

Would I have a problem installing the SLP 1.85's on a stock engine with LS6 cam and springs? They claim to give you 10% more lift. Is that going to make a horsepower difference?

JeffJeff

Sorry, they are already sold.