bunk22

First off I like to thank Orange County Corvettes and their owner, Sean Reis. He did a great job, took his time on the dyno and the car actually runs better than before, didn't think that was possible. His shop uses a load bearing dyno-jet so he was able to tune at different rpm ranges under load, as well as WOT.

I was dead set on doing at least a cam but decided not to open up the motor. So rockers aren't exactly the best bang for the buck but I went for something different. I also understand what dyno's are used for, tuning and my last dyno was a dynojet but not this dynojet. So my gains aren't exactly scientific with a different dyno, different day. The dyno tune didn't necessarily give me more power, just corrected the issues from my last tune. The prior tune (not performed on a dyno) had some lean areas and too much timing in other areas under the curve. Had some knock going on as well. Sean fixed all that and a slight hesitation during initial acceleration. My air-fuel now looks to be a nice 12.5:1 across the board. This tune is with not so great California 91 octane so on 93 octane, might get clost to that 400rwhp mark with bolt-ons. I'm moving there next month so I might have the timing altered just a bit to help when I get there. Maybe run some Torco until then. Anyway, we really wanted a baseline run prior to rocker install but didn't get the chance so this is all I've got.

Last October, I dynoed a best of:
377.7rwhp/358.9rwtq SAE

First run today, addition of only the SLP 1.85 rockers and no tuning:
393.17rwhp/381.11rwtq SAE

Best run today with tuning:
396.35rwhp/382.88rwtq SAE

Last run with the final tune:
393.02rwhp/381.31rwtq SAE

So if I take this at face value, I gained a peak of 18rwhp and 24rwtq. I don't see it with just rockers but it is what it is.

My best run in the 1/8th so far has been 8.41@89.39. I might try to get to the track this weekend to best it but the weather has been so bad recently, it may not make a difference. The DA was about 2100' on the run above and it has been between 4-5000' at the local track as of late. As far as SOTP goes, I could tell a difference. I didn't think I would but there's no doubt a nice little kick in the pants. I can post the graphs later in case anyone wants to see them.

yell03

Pretty impressive #s.

The Rockers seem like a nice mod for those not wanting to open up their engine.

Approximately 20rwhp/20rwtq is nothing to complain about.

In fact 400rwhp (60rwhp gain) from just headers, catback, air intake, rockers and a tune is very nice.

Howard

tjd113

I have been looking into this, I have seen a number of post on this and they all are showing 15 to 20 rwhp gain which is a nice mod for the price.

dennis50nj

use to do it in al my 5.0s and did it on a 460. always made a big sotp difference and a few 10ths in the 1/4. butt that was always a point or more. 1.6 to 1.72 one point equals 30 points of lift. doesnt change duration.

BEZ06

Wow - sounds great!

I'm getting ready to put the SLP 1.85 ratio rockers in mine as well.

You didn't mention any change of pushrods or anything, so I guess everything else in the valvetrain was left OE.

You didn't change the springs/retainers, is that right?

Thanks for the info,

Bob

not08crmanymore

20 hp from those alone???That's impressive!!!How much $$???Oh,and what are the stock ones on a z51 vette??

bunk22

I changed the springs and retainers. It's mandatory for the 1.85 rockers swap.

mr 35th

Very nice gain. You may also want to try doing a Jeremey Formato Ported intake. That may help get you over the 400hp mark without going into the motor.

bunk22

Actually, that's what I was thinking.

SpinMonster

Good results and I hope this serves to let the non-beleivers see that there are options to putting in soft small cams and that it is a decent power gain. This rocker swap gives 1/2 the power of a cam swap with no idle or tuning issues. For the repeatability gurus, check the hot rod magazine site for a write-up on the gains from higher ratio, roller tip, and quick lift technology for options. Even the same ratio 1.7's have a decent gain.

20 from rockers is expected and has been shown before with the crane 1.8's. Even the crane 1.7 quick lift yeild 12rwhp without issues of having to be concerned about cam mismatch. I run the crane 1.7's with an XER comp cam without issue and couldnt beleive the difference in pull. Increased ratio adds to lift and therefore gives free TQ. Roller tips reduce friction. Quick lift rockers give a combination of the two plus get rid of the needle bearings. Another advantage of the crane version is adjustablity and the eliminatin of guessing the correct pushrod length which is always a tradeoff with the stock rockers.



One more side note to the people who hear from a certain North East tuner that the cranes add a degree of instability to the valvetrain: the gen 2 chevy motors ran that style rocker arm for decades

bunk22

I was dead set on a small cam but in the end, didn't want to open up the motor for it. A medium to large cam definitely give much better gains but that's not what I wanted, at least not at this time. The SLP rockers don't have roller tips and quick lift technology so maybe going with the Crane products might yield better results.

SpinMonster

Typically on the LS1 and 6 there were gains in the 20-22rwhp but with less lift (1.8 rockers). The 1.7's are still giving some gains but they arent true 1.7's having 1.79:1 ratio off the seat and maintaining 1.72 through most of the lobe. The average with those is 12 or so but they can be used with aggressive grinds such as the comp xer as in my set-up.

SpinMonster

But they supply more lift (10%)

bunk22

Yeah you're right. Perhaps you told me this but it went from .525 to .571 with the 1.85's.

P-Colavette

I just did the 1.8 rocker swap on my '05, and after it was all said & done, on the same dyno that has been used since day 1, my car is only making 376rwhp. I did not change the valve springs, and I know that is a problem, as at 6000 rpm, the hp/tq makes a right angle turn straight down ! The engine also sounds like it's hitting the rev. limiter when this happens. The tuner said it's floating the valves, or getting "Valve Flutter ". I have a set of the AFR dual springs, and they are going in next, followed by a ported factory intake, to try and get that magic number at the rear wheels.



Steve.

My List of mod's..
American Racing L/T's , Cat Delete (all), MagnaFow X-pipe & exhaust,
Custom tune by James of RWTD, De-Screened MAF, David Farmer DIY CAI.
Harland Sharp 1.8 roller rockers.

bunk22

Hope it goes well. Are you in P-cola? I'm moving there in a month.

Abomination

so bunk22 and spinmonster is this the kind of item you want to install if your putting a cam in the car?? I guess I dont understand why rockers ( I may just misunderstand what they do) Doesnt it just make the cam in the car bigger? If you were installing a cam wouldnt you just pick the lift you want on the cam itself? Or is it the reduction in friction that big of a deal?? Thanks for your time.

P-Colavette

Is my home, when my Rich Uncle doesn't have me off traveling, meeting new & interesting people..... Currently in Augusta, Ga. however, I am taking some time off, and I will be in the Pensacola area for a couple of weeks. Let me be the first to welcome you to the best kept secret on the Gulf Coast ! If you need any help when you get to P-Cola, just give me a shout......



Steve.

AutoCutter

Right on! Yes, were are those doubters and nay-sayers that gave me such a rash of poop for even suggesting rockers over a cam swap. Besides it is quicker and cheaper and you have zero chance of ending up with crap cam.

Anyway, why rockers and not just a bigger cam-well there is only so much lift you can get without effecting duration, LSA, etc..etc and if you don't want to change how the motor currently behaves then your option is a soft cam. I personally don't think the soft cams are worth the trouble, but that's just me. Finally, SLP's or cranes rockers are spot on with their ratio's/lift whereas OEM's may be all over the place-same for the rods too. Kartech did some interesting stuff when the LS2 came out with moderate cams and SLP's 1.85 making some really good horse power.

dennis50nj

its usally done when you picked the wrong cam. so you still have a chance to change the power range. i bought a 5.0 it had a stick cam. it was an aod real dog of the start so instead of changing cam i changed the rockers it gave me 30 more points in lift duration stayed the same. it changed the power to lower rpm but also spread it across the full rpm range. also very good in nitrous applications without being a split pattern so you have the best of both worlds