rtobrian

iTrader: (1)

I'm looking into putting a set of 1.8 rockers on my 2002 T/A. It was suggested that I use Comp Cams 26918 springs which are suitable up to .600 lift. Does anyone know what the lift is on the stock springs and would the ls6 springs be a decent upgrade? Thanks

PREDATOR-Z

Why not just stick a cam in there instead of messing with the 1.8.
If money is an issue, you could at least get the basic cam kit from TSP and get much more out of that.
Like a 220/220
http://www.texas-speed.com/item_deta...?ProductID=333

kenp

iTrader: (9)

The answer to your question is probably not. The info I've seen is that the beehive design spring has problems with harmonics and with valve float. As I recall, it occurrs around 5800 to 6200 RPM's. Based on the stuff I saw on the subject I changed to an aftermarket spring and Ti retainers when I installed my VHP 1.8's. There's no question that you can buy a cam for less than the VHP's and around the same price as some other roller tip rockers. The books written by the experts tell us that the one thing that will "wake up" your LS1 is a cam swap. That's probably correct. On the other hand, if you don't want to have to remove your radiator and dismantle the front of your engine, higher lift rockers are a fairly simple alternative. The VHP's will ramp your valves open sooner and give you more lift and you won't have to worry about spitting needle bearings into your engine from a failed rocker. If you go to the Crane website and read their technical data it makes sense that your engine will breathe a litle deeper after they are installed. The sound of my engine changed very noticibly after my rocker install. Bottom line is that if you are going to use any method to create more valve lift and thus closer proximity to the top of the piston, you will probably be buying cheap insurance with a better spring other than the LS6. How much HP do you really gain? I don't know because I haven't dynoed my car yet. But my seat-of-the-pants indicator tells me the car runs better.

bigdsz

iTrader: (1)

The 918's are a great spring, very efficient , however I would be more comfortable with duals after about .590. On the other hand I think it is moronic to pay $700 for rocker arms that are a band-aid instead of a bigger cam. None of the real, legitimate racers on this site, to my knowledge, mess with the Crane rocker hype.

Gman2002Z06

bigdsz...What constitutes a "legitimate racer"...You call it moronic to put a set of roller rocker on a performance engine...A modification that is proven to add horsepower and decrease engine frictional losses...But you list a Shaner Throttle body as one of your mods...Now there is a waste of $200 when the factory unit already flows enough air to fire a 450 rwhp engine...

The rockers are worth the money...Don't kid yourself into thinking otherwise...I gained an easy 2~3 tenths of a second from 10~100 mph acceleration runs with the addition of the rockers...

Peace...Gman

bigdsz

iTrader: (1)

I would like to see some examples of guys running 11.00 or better running 1.8 rockers. As far as I'm concerned they would be few and far between. Most sponsors web sites specifically reccommend against 1.8's.It's not logical when you can get a cam for half the price. Aftermarket rockers with solid lifters for instance make sense, but for 99% of the LS1's no way.

vettenuts

iTrader: (4)

Do you have any concerns with the Comp 918's and the stock timing chain? Why not the Crane valve springs, they are double and have a lower seat pressure. Not sure you need that much seat pressure with only a 1.8 rocker installation.

As for why some want to install rockers rather than a cam, I for one don't really want to remove the steering rack and all the other stuff to get at the cam. I would also tend to go with a mild cam to keep my streetability and valve train life long as I like to take the car on long trips and don't race it on a track, but that is me. Others would go with a more aggressive cam selection for higher peak HP, but that is not what I personally am looking for. Guess what I am trying to say is that while some have no problems opening them motor and installing a cam, I am leaning towards a bolt on approach and the Cranes seem to have a lot of good feedback both as far as valve train noise and dyno results are concerned.

JohnnyStorm

iTrader: (2)

02 LS6 Spring SD1423 Spring

76.4G - 67.9G = 8.5G x 16 = 136G

02 Steel Retainer Titanium Retainer

11.3G - 9.3G = 2G x 16 = 32G

The LS6 Spring is heavier according to my Gram Scale! And has less seat and open pressure than the SD1423. I'll take the aftermarket spring over the LS6 springs and I'll sell you my brand new 02's. Interested?

Here's what GM did right:

Stock LS1 Stock 02 Ls6

Int Valve 99.4G - 72.7G = 26.7G x 8 = 213.6G

Exh Valve 85.6G - 64.8G = 20.8G x 8 = 166.4G

I agree with what you said about Valvetrain weights, that's why I went this route with my soon to be installed; as soon as I finish porting & polishing them that is 04 LS6 heads.

vettenuts

iTrader: (4)

I thought part of the theory behind the beehive design was that you don't accelerate the entire mass of the spring, but rather the top coils down as the valve opens. As a result, the amount of spring length that you are accelerating may be smaller with the beehive design.

I agree on the valves, just wish they weren't so darn expensive.

Gman2002Z06

bigdsz...The choice for going to the higher ratio or the "real" racers is more of a design constraint...You can only get your lobes so big and sooner or later the cam won't fit in the engine...Hence you go with the bigger ratio rocker to keep the profile of the cam within reason...New Z06 comes from the factory with 1.80 rockers...NHRA engines run ratios in the 2.5 range to get the lift they need...

Peace...Gman

bigdsz

iTrader: (1)

The fact remains that 99% of us can get by with OEM rockers. What is really objectionable is the price, $700 IMHO is an absolute rip off.

mrr23

iTrader: (3)

for the $669.00 you get the accelerated lift rockers, pushrods, guideplates, screw in studs, and poly locks. now, go price everyone elses with all those parts and get back with us on if it's a rip off. also, no other rocker has consistently given the power increases the vinci/crane rockers do. none.

real racers, huh. i guess NHRA, IHRA, NASCAR, dirt track, and all those other forms of racing just aren't 'real'. only the people that post and race here are. all those 'fake' racers just really don't know what they're doing. higher ratio rockers have been used for decades.

here, i'll post the graph again. vinci did the larger cam with stock ratio vs smaller cam with larger ratio just to prove/disprove what's been said. guess what? the smaller cam/larger ratio won. it has more usable power than the larger cam/stock ratio set up. just because it's cheaper to throw a cam in, doesn't make it right. i really wonder how much more power the guys with stock rockers would make with the vinci/crane rockers?

also, start giving some viable data as to why you can't use 1.8 on the more aggressive lobes. other than just because some sponsors say not to with their cams. i can see if there's piston to valve issues or spring issues. but not just because of ramp issues. remember, those 'fake' racers are doing it.

here you go. comp cams 220/224 .581/.581 115 LSA with 1.7 accelerated lift rockers vs vinci 055 216/224 .551/.551 (1.7) 113 LSA with 1.8 accelerated lift rockers (brings total lift to .589/.589) smaller cam larger ratio did better. the comp even had the accelerated lift rocker advantage as well. i'm still waiting to see it the other way around and win.

mrr23

iTrader: (3)

and i'll post my graph again showing where i swapped from stock rockers to he vinci/crane 1.8 accelerated lift rockers and dual springs with stock cam in the wife's 99 formula

dyno 9 before
dyno 11 500 miles later
dyno 14 10 months later

mrr23

iTrader: (3)

also, i'll give you the link to the article where chevy high performance had vinci install and dyno the 1.8 accelerated lift rockers and dual springs in a 5.3L truck.

http://www.stealthram.com/reddogplan.htm

Ed Curtis

OMG!

Really!

Ed

mrr23

iTrader: (3)

now that we got that whole rip off thing out of the way, what does that rocker kit consist of? $60.00 is nothing when you are at that level of spending. $60.00 is a matter of buying something that works better. but hey, you already know that as well. just my opinion that vinci/crane has the better product at this point. cheaper doesn't make it better.


now. back to the main issue. why is it that you can't use higher ratio rockers with aggressive ramps? everytime i ask, it gets danced around. you know, because one vendor says so, or it's the aggressive ramps, or because vinci/crane rockers are ripping you off on the price.

bigdsz

iTrader: (1)

Brian it's probably too late in the day and you've already left the office for the long weekend, but next week when you get back please , please explain to Robert why his reasoning on these 1.8 rockers is without merit. Every week or two just like clock work Robert brings out his dyno graphs to pitch the Crane rockers, ad nauseum. The same old story line is boring, if Crane is aware of it I'm surprised they continue to allow it.

mrr23

iTrader: (3)

if crane needs to be aware of anything, it's you calling them rip offs. is this the best you can do? " aw i can't come up with a counter to the actual proof that's brought to the table, that i have to try and make mrr23 look like some kind of bad guy." mark campbell is completely aware of my postings. after all, he is a member of ls1tech. and if he or roger vinci thinks i've said something incorrect, they'll let me know.

if there's anything that's clock work it's you that comes in when someone asks about higher ratio rockers and all you can do is say it's a waste of money and crane is a ripoff. if you can't handle my counter to your objections with any hard set data and proof, then don't post until otherwise.

remember everytime i come in, you have made your stance first. and i mean every time. your only counter is to try and attack me personally. just because you have some beef with vinci and/or crane, doesn't mean you can come out and attack me personally. i don't attack you. just your invalid opinions. now watch, seeing as i am only defending myself, we'll have moderator come in and tell us to take it to PM. then i'll get a PM saying that i'm wrong in defending myself.

you stay in your camp, and i'll stay in mine. and until someone can provide proof to counter what vinci and i have proven, i'll keep showing it.

mrr23

iTrader: (3)

don't have brian do it for you, you say it's worthless, you convince me otherwise. if you can't explain it, then don't say it. i say it works and i bring dyno and track proof.

bigdsz

iTrader: (1)

Let's get down to brass tacks, I am going to list a number of the premier sponsors on this site whose collective opinions I value highly. Many of these sponsors build their own engines, have their own machine shops and design their own cams, as well as do various installs. Please point out to me and other doubters which of these shops are reccommending 1.8 accelerated lift rockers as an alternative to installing a proper size cam to meet that particular persons performance requirements. Many of these shops specifically state that they do NOT reccommend use of 1.8 rockers.

Shops that come to mind are Thunder Racing, Cartek,Futral,HPE, LME, LG Motorsports, Lingenfelter, Livernois, MTI, Next Level Performance, Rapid Motorsports, SLP, Speed Inc, Texas Speed, T Byrne. Challanging , huh? After market rockers do in fact have a niche for our engines , albeit limited.