SR Rockers; installed and tuned; data inside!
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SR Rockers; installed and tuned; data inside!
Bought some SR ("split ratio"; first generation of ZZP'* current "ER") rockers used from ClubGP for $150 a few months ago:
These are 1.85 intake / 1.80 exhaust, modified stock rockers.
Finally got them installed (on stock springs/retainers; all shift points < 6000 rpm) and tuned over the past week; here'* the VE data in the continuing mod saga:
The rockers show an increase in calculated VE across the entire range from 2800 rpm up. I was hoping for more at the high end (more on that later); however, I was pleasantly surprised by the large positive impact even at 3600 rpm and below. The car pulls strong and steady from a dead stop, and I'm quite pleased.
Looking at the peak VE value, it seems that torque peak may have shifted up somewhat, perhaps by about 200 rpm; but I will still base my calc'* on a 4200 rpm torque peak / 5200 rpm hp peak for now.
So here'* the new incremental calculated improvements vs mod levels:
Mod Level---Torque (@4200rpm)---HP (@5200 rpm)
Stock-----------+0 ft-lb--------------------+0 hp
PLIM------------+10 ft-lb-------------------+8 hp
PEM-------------+6 ft-lb--------------------+5 hp
L67TB----------+16 ft-lb--------------------+17 hp
SRR-------------+4 ft-lb---------------------+9 hp
For a total of about +36 ft-lb @4200 rpm and +39 hp @5200 rpm over stock.
Having bought alot of hard parts used, I'm about $350 into parts/gaskets with what'* listed above. That'* less than $10/hp (if my calculations are close), so not too shabby.
(As always, these are calculated estimates only, not yet backed up by actual dynos...)
I think that I could get more out of these rockers with upgraded valvesprings; I believe I have--and have long had--some valvefloat issues at the high rpms. Plus, my calculated hp curve is telling me to start thinking about shift points beyond 6000 rpm, for which I would need better springs. Furthermore, I think I'll get ALOT more out of these rockers (and all the mods, for that matter) once I port out the spare heads:
http://www.bonnevilleclub.com/forum/...ic.php?t=77163
Heads and springs will likely be a Fall-Winter project, as the rest of my Summer car money is now earmarked for tires, brakes, and maybe struts. Unless I come up with some really low-cost ideas, I'm probably set performance-wise for the next few months.
These are 1.85 intake / 1.80 exhaust, modified stock rockers.
Finally got them installed (on stock springs/retainers; all shift points < 6000 rpm) and tuned over the past week; here'* the VE data in the continuing mod saga:
The rockers show an increase in calculated VE across the entire range from 2800 rpm up. I was hoping for more at the high end (more on that later); however, I was pleasantly surprised by the large positive impact even at 3600 rpm and below. The car pulls strong and steady from a dead stop, and I'm quite pleased.
Looking at the peak VE value, it seems that torque peak may have shifted up somewhat, perhaps by about 200 rpm; but I will still base my calc'* on a 4200 rpm torque peak / 5200 rpm hp peak for now.
So here'* the new incremental calculated improvements vs mod levels:
Mod Level---Torque (@4200rpm)---HP (@5200 rpm)
Stock-----------+0 ft-lb--------------------+0 hp
PLIM------------+10 ft-lb-------------------+8 hp
PEM-------------+6 ft-lb--------------------+5 hp
L67TB----------+16 ft-lb--------------------+17 hp
SRR-------------+4 ft-lb---------------------+9 hp
For a total of about +36 ft-lb @4200 rpm and +39 hp @5200 rpm over stock.
Having bought alot of hard parts used, I'm about $350 into parts/gaskets with what'* listed above. That'* less than $10/hp (if my calculations are close), so not too shabby.
(As always, these are calculated estimates only, not yet backed up by actual dynos...)
I think that I could get more out of these rockers with upgraded valvesprings; I believe I have--and have long had--some valvefloat issues at the high rpms. Plus, my calculated hp curve is telling me to start thinking about shift points beyond 6000 rpm, for which I would need better springs. Furthermore, I think I'll get ALOT more out of these rockers (and all the mods, for that matter) once I port out the spare heads:
http://www.bonnevilleclub.com/forum/...ic.php?t=77163
Heads and springs will likely be a Fall-Winter project, as the rest of my Summer car money is now earmarked for tires, brakes, and maybe struts. Unless I come up with some really low-cost ideas, I'm probably set performance-wise for the next few months.
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andrew is the a big difference between those and the ER rockers .what i have heard is that the ER has a bit more top end .but for 150 that a good deal
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Originally Posted by firebuick
andrew is the a big difference between those and the ER rockers .what i have heard is that the ER has a bit more top end .but for 150 that a good deal
zzp mods these stock rockers by filling in the original hole or "cup" the pushrod end fits into, then re-grinding the "cup" a little closer to the pivot point. You can see in the photo above that the bottom row has the re-ground cups a little closer to the pivot...these are the 1.85'*, the top row is the 1.8'*.
Between a measured manufacturing tolerance of +/- 0.03" from rocker-to-rocker on the location of the re-ground cups, plus the likelihood of unpredictable amounts of deflection from piece-to-piece on what are at heart stock rockers of unknown mileage and unknown mileage consistency (did all the cores come from the same original engine? I dunno!), I wouldn't dare try to quote an actual lift number with any more than about +/- 0.05" precision. And I certainly wouldn't expect any major difference between SR'* and ER'* :P
These things do go up used on ClubGP quite often for about that price...I feel lucky that the ones I got were extremely clean and in such good condition.
Note that the pedestals are modified too...the U-shaped cut-outs that guide the pushrods are ground deeper, because the pushrod geometry is changed. If you buy used, make sure the modded pedestals are included.
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if the ratio is 1.84 and 1.81 and i have to buy new one would the extra cost of true roller 1.8 rocker be better .i think there 100$ more butt the have a roller tip and they don't flex and the ratio should be more acurate
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My personal opinion is that roller rockers are an unnecessary extravagance for our applications. But if you've got the dough, go for it!
EDIT: Let me add: even if the stock rockers deflect by as much as 0.040" (number from zzp website), the SR'* or ER'* still give a intake lift on the stock cam of just over 25% of the valve diameter (and even more than 25% with a deflected 1.8 on the exhaust). According to engine theory, there is little or nothing to be gained by increasing lift more than 25% of valve diameter, as the area of the imaginary cylinder between the stock valve margin and the valveseat equals the area of the valveseat opening at this lift.
A 1.8 with no deflection will give ever-so-slightly more lift than a 1.85 with 0.040" deflection on the intake, and significantly more than a deflected 1.8 on the exhaust; since you already have all the lift you need on the SR'* or ER'* (assuming you have stock valve diameters), the fact that the roller rockers don't deflect (as much) is not, theoretically, an issue.
The rollers will reduce side-to-side motion of the valvestem, and should reduce valveguide wear...but that'* more of an issue in a race-built or strip-only car. For our 90%+ street cars, I don't see it as worth the extra money.
EDIT: Let me add: even if the stock rockers deflect by as much as 0.040" (number from zzp website), the SR'* or ER'* still give a intake lift on the stock cam of just over 25% of the valve diameter (and even more than 25% with a deflected 1.8 on the exhaust). According to engine theory, there is little or nothing to be gained by increasing lift more than 25% of valve diameter, as the area of the imaginary cylinder between the stock valve margin and the valveseat equals the area of the valveseat opening at this lift.
A 1.8 with no deflection will give ever-so-slightly more lift than a 1.85 with 0.040" deflection on the intake, and significantly more than a deflected 1.8 on the exhaust; since you already have all the lift you need on the SR'* or ER'* (assuming you have stock valve diameters), the fact that the roller rockers don't deflect (as much) is not, theoretically, an issue.
The rollers will reduce side-to-side motion of the valvestem, and should reduce valveguide wear...but that'* more of an issue in a race-built or strip-only car. For our 90%+ street cars, I don't see it as worth the extra money.
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ok thank you andrew i was sure you had a good opinion on that .so it will be ER or SR rockers .im getting a high flow cat install tommorow after i wil get into the engine soon
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