Installed Crane 1.8's
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Pro
Joined: Sep 2003
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From: Calgary Alberta
Installed Crane 1.8's
I decided to try the crane 1.8 roller rockers, and see just what kind of a difference they would make. I also installe the comp 918 springs and titanium retainers to compensate for the slightly higher lift.
Dyno before the rockers - with Blackwing, shorty headers, ported TB, LS6 intake manifold, SLP 85mm MAF, high flow cats, B&B PRT's, 3:42 gears (some say that the lower gears reduce your hp reading on the dyno), and stock wheels & runflats. 334.3 hp @ 5850 rpm's & 334.7 lb.ft. of torque @ 4700 rpm's. The a/f ratio was at 13.5 (only have 91 octane here).
Dyno after the 1.8 crane rocker install - same mods, but with 20 inch iforged wheels (possibly a lower reading than with the stock wheels and tires). 340.2 hp @ 6000 rpm's & 321.9 lb.ft. of torque @ 4700 rpm's. a/f also at 13.5.
Only a 5.7 hp gain, but a reduction of 12.8 lb.ft. of torque. doesn't seem worth the money in my opinion.
Anyone else out there get similar results? Maybe the bigger wheels and tires would account for the big torque reductions.
Dyno before the rockers - with Blackwing, shorty headers, ported TB, LS6 intake manifold, SLP 85mm MAF, high flow cats, B&B PRT's, 3:42 gears (some say that the lower gears reduce your hp reading on the dyno), and stock wheels & runflats. 334.3 hp @ 5850 rpm's & 334.7 lb.ft. of torque @ 4700 rpm's. The a/f ratio was at 13.5 (only have 91 octane here).
Dyno after the 1.8 crane rocker install - same mods, but with 20 inch iforged wheels (possibly a lower reading than with the stock wheels and tires). 340.2 hp @ 6000 rpm's & 321.9 lb.ft. of torque @ 4700 rpm's. a/f also at 13.5.
Only a 5.7 hp gain, but a reduction of 12.8 lb.ft. of torque. doesn't seem worth the money in my opinion.
Anyone else out there get similar results? Maybe the bigger wheels and tires would account for the big torque reductions.
Drifting
Joined: Nov 2001
Posts: 1,791
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From: NE PA
I switched from a set of SLP 1.85 rockers to the Crane 1.80 roller rockers, lost ~.010" of valve lift in the process due to the lower ratio, and still gained 10 rwhp and 8 rwtq with the Cranes over the SLPs. 
Your conclusion isn't fair because I think the wheel change made any real comparison impossible.
Your conclusion isn't fair because I think the wheel change made any real comparison impossible.
Last edited by XTrooper; May 30, 2005 at 09:34 AM.
Collections Hold
Joined: Aug 2002
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From: Fort Wayne Indiana
We typically see 16/11 flywheel gain on nearly every engine we've installed them on using a Superflow SF-900 engine pump and the power curve is MUCH broader, especially in the low-to-mid range area.
Burning Brakes
Joined: Nov 2004
Posts: 988
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From: Livermore CA
Comp 918s are a beehive type spring, I have heard that some beehive springs have natural frequencies which are excited in the 4500-6000 rpm range in LS1/LS6s and the noise from their vibration triggers the knock retard. You can't hear this noise over the roar of the engine at these rpms but a scan tool should reveal if you are experiencing any knock retard which would be stealing your torque.
Le Mans Master
Joined: Oct 2003
Posts: 6,126
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From: Streamwood illinois
i put on 918s and 1.85 Roller rockers and gained nothing at the track. ET/MPH withing .05 between the two days. DA was very similar and AFR was identical. This was on a stock C5. Wasnt worth it. Ditto on the LS6 intake.
Dave
Dave
Melting Slicks
Joined: Jul 2004
Posts: 3,353
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From: Richmond Hill Ontario
Originally Posted by Chrispy
Those rims are REALLY skewing the results. Borrow a set of stockers and redyno. (rotational weight from the bigger wheels will eat a lot of power)
Tino
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Drifting
Joined: Nov 2001
Posts: 1,791
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From: NE PA
Originally Posted by TT_Vert
i put on 918s and 1.85 Roller rockers and gained nothing at the track. ET/MPH withing .05 between the two days. DA was very similar and AFR was identical. This was on a stock C5. Wasnt worth it. Ditto on the LS6 intake.
Dave
Dave
Collections Hold
Joined: Aug 2002
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From: Fort Wayne Indiana
We use the Crane Cams dual valve springs w/ titanium valve spring retainers and to the person that stated that there is no other spark delivery tuning necessary with these types of mechanical modifications other than fueling...... Well, by not optimizing ALL areas of the calibration, especially by not performing any adjustment in spark delivery, you are certainly leaving power on the table by not doing so as evidenced by no E.T. gain in your combination.
Spark delivery DEFINATELY matters....FYI
Spark delivery DEFINATELY matters....FYI
Last edited by DTE Powertrain; May 30, 2005 at 02:43 PM.
Drifting
Joined: Nov 2001
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From: NE PA
Originally Posted by TT_Vert
Read, exact AFR. I did tune it. At WOT the only thing that matters is AFR really. Same timing tables
Dave
Dave
Drifting
Joined: Nov 2001
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From: NE PA
Originally Posted by Just Enough
DynoTech Engineering, What springs do you typically use for the Crane 1.8 install?
Le Mans Master
Joined: Oct 2003
Posts: 6,126
Likes: 19
From: Streamwood illinois
i did play w/ spark advance but got nowhere. No ET or MPH gains as far as adding/removing timing or adding removing fuel with the mods. If AFR is the same (13.0:1) and spark timing is the same why would changing them affect anything? I did mess w/ timing but it didnt do a thing to ET or mPH. What else would you have to change when adding RRs or the intake? Mind you this was on a pretty stock car so this could be why there were no gains, but I can guarantee I did everything to try to get power from them. I didnt want to have to take them back off. I can give more details as far as tuning changes, time slips, Density altitude and logs of runs in HPT if anyone is interested.
On a stock to mildly modded car, the springs, rockers and ls6 intake will give you almost nothing.
Dave
On a stock to mildly modded car, the springs, rockers and ls6 intake will give you almost nothing.
Dave
Thread Starter
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Joined: Sep 2003
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From: Calgary Alberta
When I get back into town next week I will put the stock wheels and tires back on and dyno the car again. I'm curious myself as to wether there is any real significant change from just wheels and tires.
I should also make everyone aware that all of the necessary tuning was done to achieve max hp and torque. That last dyno run was #6, the first five runs were for tuning.
I should also make everyone aware that all of the necessary tuning was done to achieve max hp and torque. That last dyno run was #6, the first five runs were for tuning.
Team Owner
Joined: Mar 1999
Posts: 22,025
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From: At the beach in little Rhody
While I am interested in the rockers, I am nervous about going to stout with the springs with the stock timing chain. To change it, I might as well do the cam at that point.