mrr23

iTrader: (3)

the graph that notes the 1* of knock was the before graph. look at the top of the graph. dyno 009 adding the MAF ends and airlid. dyno 011 rockers. you can see where the knock happened on the blue line. right where the sudden dip was right about 5500. i guess i should also state the dyno was the 1.89 accelerated lift rocker kit and VHP dual springs. these aren't your standard 1.8 rockers. with the accelerated lift technology that VHP and Crane are developing, the rockers start off a 1.89 ratio. then at about .250 lift, they move back to about 1.82. here's a tech page VHP put up explaining this new technology. using a tech II scanner during the runs, the o2s were reading 890-910 on the before run. as far as the baro and temp readings, it was colder on the before run. look at the CF (correction factor) for run 009. .96 correction. it had to take away .04 per hp. the after run had a CF of 1.00 no corrections needed. the dyno that VHP has is the DOS based dynojet. so it doesn't graph the a/f ratio. you have to watch the meter during the run. or do what they do, which is use the tech II scanner to see what the computer sees. which is more accurate. using the a/f ratio meter in the tailpipe measures the gases AFTER it goes through the cats.

http://www.vincihighperformance.com/...20PAGE%20.HTML

and here:
http://www.vincihighperformance.com/...RTSPARENT.HTML

mrr23

iTrader: (3)

well that's funny. because the o2s were reading 990-1002 before the addition of the airlid, filter and MAF ends. then it went to 890-910. but like i said, they also have a meter they watch and video during the runs to go back over and see what goes out the back as well. using a tech II during a run tells alot more than what an a/f meter does. like knock, MAP sensor readings to determine vacuum. before the airlid, filter and MAF ends, the MAP sensor was reporting 5" of vacuum. after, the vacuum went to 1".

mrr23

iTrader: (3)

which is why they also use the wideband during the runs. the software in the DOS based dynojet just doesn't graph it.

mrr23

iTrader: (3)

no this car has not tuned yet. waiting on the install of the heads. all parts and subsequent dynos related to them are for just installing the parts only. so, the gains you see are the parts only. click the pink banner and go to timeslips to see all that's been done so far.

mrr23

iTrader: (3)

i forgot. i do have a dyno showing the a/f ratio. here it is. pretty much 13.0:1 across the board.

mrr23

iTrader: (3)

and that's a stock tune. i've got a dyno showing my all stock 00 formy with a 11.8:1 ratio the same day. went back two weeks later. only added a SLP airlid and it went to 12.8:1. also the hp went from 276 to 291 hp ??? i know why it happened. guess?

all stock http://www.stealthram.com/familypics...et/cmnasae.jpg
SLP airlid only http://www.stealthram.com/familypics.../slpairlid.jpg

robtest

I found needle bearings attached to the magnetic oil pan screw, so I had to replace the rockers. I thought "since you are in there anyway, why not add a performance part???" I ended up with the SLP 1.85 rockers and springs kit, plus added their SLP Cold Air Package, 1998-99 LS-1 Camaro/Firebird (FlowPac). I had my local mechanic do the rocker/springs. I spent a Sat. morning installing the FlowPac. After the install, it kinda sucks you back into the seat on take-off, which it didn't do before. I have a little G-tech meter that times my 0-60 at 5.3. Overall, I am very happy with the upgrade.

I am not real handy with engines and the technology of engine dynamics. I have seen a cam somewhere that said it was for 1.8 rockers, but can't find my way back to the link. Would someone be so kind as to explain a little about matching a cam to these higher lift rockers? Or perhaps a link to a good tutorial? Sorry to be such a newbie with all this lift and duration stuff. I am pretty handy with a Novell or Windows 2003 server though!

XTrooper

Not true. It's very simple to order a custom grind cam to match your higher ratio rocker arms down the road if that's what you decide to do. I've done it twice now. In the meantime, you can make pretty good gains over stock with just a rocker arm swap, an easy job almost anyone that can turn a wrench can do.

My A4 car with CAI, headers/exhaust and still using the LS1 intake manifold made 325-330 rwhp with this mod.

Just getting the cam you want in the first place is certainly the cheaper route, but higher ratio rocker arms allow you to get gains now without the work and/or expense of a cam swap They're an especially good option for those that have no intention of ever changing their cam.

XTrooper

All you need to do is find an off-the-shelf cam that has a lobe lift that isn't too high for your 1.85 rockers or do like I did and just order a custom grind with exactly the specs you're after. Either way, there are plenty of choices. To figure out your valve lift with your 1.85s (or any rocker arm ratio) here's what you do.

Divide the cam's .050" valve lift by the stock rocker arm ratio (in the case of the LS1, 1.7). This will give you the cam's lobe lift. If the cam has different valve lift numbers for intake and exhaust you'll naturally have to do this for both.

Now take that lobe lift number(s) and multiply it by the new rocker arm ratio (in your case, 1.85).

You now have your new valve lift number(s).

P.S.- Take a look at this page from the Thunder Racing web site. Every one of the Comp and Crane cams listed has the comment added "Works well with Crane 1.8 Roller Rockers." They'll work just as well with your SLP 1.85s.

http://www.thunderracing.com/catalog...&vid=7&pcid=51

marc_w

Wondering something here...

I've got a cam that produces .530" at the valve. I want to add higher ratio rockers. I'll get .550" at the valve.

Now say this other guy comes along with my same motor decides to drop in a cam that produces .550" at the valve right off the bat. He has no intention of running higher ratio rockers.

Is there anything to be gained in the .020" less movement that the lifters, pushrods, and end of rockers have to move in "my" setup, vs "the other guys"? (not factoring in variable rate rocker technology or 'other' rocker-related-gains)

If not power, maybe longevity or resistance to valve float?

XTrooper

The "less movement" you speak of is non-existent. .550" of valve lift is .550" of valve lift.

marc_w

....But the lobes of the cam are not moving the lifters and pushrods as much. The rockers are adding in that extra .020...

XTrooper

Yes, I realize that, but the wear you speak of is related much more than anything to 1. the lift at the valve (which affects the valve spring) and 2. valve spring pressure (which affects all the related components) neither of which are any different in either case. I seriously doubt .020" more or less movement on the rocker arm side has any practical effect.

marc_w

I see now..........

Thanks for setting me straight.

mrr23

iTrader: (3)

i'll disagree about the .020" lift not having any practical effect. look at the graphs i posted. that was only adding the VHP 1.89 accelerated lift rockers to the stock cam in the wife's 99 formula. they start off at 1.89 and end up at about 1.82 at max lift. it's all about getting the valve open/closed as quickly as possible. i also picked up a tenth and .5 mpg at the track with them also.

XTrooper

Umm........you missed the whole point of our discussion and what we were talking about regarding the .020". We were talking about a detrimental effect. Read my other posts. I'm on your side!

Mark Campbell

Marc,

With the cam you have and 1.8 rockers, you will have slighly more area under the curve than by getting the .550 lift with the cam only. This is because there are limits to how fast the lifter can rise with the lobe only. Using the ratio of the rocker to enhance the lift at the valve actually increases the area under the lift curve and this truly leads to increased power and a wider power band. This is the premise of the Crane "Quick-Lift" design. We know this works and it has recently been proven on some "world-class" endurance cars. Our 1.7 (1.79 off the seat) "Quick-Lift" stud-mounted rockers were more than 14hp better than one of the best respected shaftmount 1.7 systems in an "unlimited bucks" racer. Power was better everywhere in the power band. Idle increased 350 rpm changing rockers only and idle vacuum increased 1"Hg. Sorry, but I can't divulge the team or the type of racing as they want to keep their "advantage" a secret!! Our 1.8 Quick Lift rockers will give you more. (The race team is limited to 1.7ratio rockers). Just try them, you will like them. The advantage is all in the body geometry and the quality of bearings we use. That's why ours cost a little more than other brands!!

Mark Campbell
VP, R&D Crane Cams

XTrooper

Mark,

I'm intrigued by these roller rockers of yours. Do you think I'd see any worthwhile increase in power using them in place of my stamped 1.85 rockers even with the slight decrease in valve lift (1.8 vs 1.85)?

marc_w

Wow... thanks a lot, Mark.

I'm already sold on getting a set of 1.89's. I was just wondering if the comments like, "If you want X-amount of lift, buy a cam that'll give you that and save your money by not buying rockers", are true or not... even for generic/straight 1.8 ratio rockers.

Mark Campbell

Good Afternoon XTrooper,

Let me answer that question this way. There are sometimes reasons why a component doesn't make the power expected. These can vary, but usually are because they aren't installed quite correctly. In all of our tests of competing rockers, we have not yet found one that makes more power than ours. I am so confident of the quality and performance of our "Quick-Lift" rockers that I will guarantee their success. If you purchase a set of these rockers and they don't make more power, I will buy them back from you. I'm not making this offer to the entire site, just you!!! If they work, please post it on the site. If they don't make an increase, call me so I can check subtleties about your installation; then, if they still don't make an increase, you can tell the world and I will still buy them back. That's a no lose proposition. If your interested, PM me and I will get them to you at the best price possible. I am leaving for the SEMA show after work today. I will not be back in the office till Nov. 8th, so that is the earliest I could return your PM!

Mark Campbell