dyno results with crane gold rockers, dual springs and Ti retainers
07-19-2005, 07:03 PM
#21
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gmblack3: I didn't mention having to change my valve springs to you specifically because you were getting the Crane duals which I switched to and that solved my problem so I honestly didn't anticipate you having one. The shorter pushrods were for my particular application and necessary only because I had my heads milled .035". 
I did, however, give the whole story of my initial problem and the solution to it in an earlier post.
https://ls1tech.com/forums/showpost....85&postcount=1
I did, however, give the whole story of my initial problem and the solution to it in an earlier post.
https://ls1tech.com/forums/showpost....85&postcount=1
07-19-2005, 07:09 PM
#22
Dumb question, with the exception of a dip at about 2,500 RPM, there doesn't appear to be any indications of spring issues, or wouldn't it show up. I would think we would see some type of dip later in the curve. Also, since the Crane "system" was used, would spring harmonics be expected? I don't remember on the 01 Z06, they didn't introduce the lighter valves yet, correct?
07-19-2005, 08:21 PM
#23
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Originally Posted by XTrooper
gmblack3: I didn't mention having to change my valve springs to you specifically because you were getting the Crane duals which I switched to and that solved my problem so I honestly didn't anticipate you having one. The shorter pushrods were for my particular application and necessary only because I had my heads milled .035".
I did, however, give the whole story of my initial problem and the solution to it in an earlier post.
https://ls1tech.com/forums/showpost....85&postcount=1
I did, however, give the whole story of my initial problem and the solution to it in an earlier post.
https://ls1tech.com/forums/showpost....85&postcount=1
Thanks for your response.
07-19-2005, 09:35 PM
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my first thought when looking at the graph suggests an initial burst knock. was there any data logging done to try and detect this? case in point, here's one of my graphs where i did back to back runs. the first one i went to start the run and it downshifted on me. so, i held the rpms up higher. unfortunately it was still in knock retard and finally gave it back in the upper rpms. as you can see on the next run, it wasn't there.
07-19-2005, 09:35 PM
#25
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Originally Posted by Roger Vinci
My I step in here? Let's take one thing at a time. Your baseline dyno runs were in November right? A lot can happen in 8 months, especially to a performance engine. If I remember correctly, you broke a spring on your car. At this point, the integrity of the engine is suspect i.e. compression, internal damage,etc. The vehicle should have been dyno tested right before the rocker install to be at all credible. That being said, Georgia is hot and wet in the July and dry and cold in November. Your graph does not show any weather information. I can tell you, having run a Dynojet for ten years in Florida weather, one can never expect to regain the losses produced by bad weather conditions from the SAE correction factor provided by the Dynojet software. It stinks but it's a fact and we have to deal with it everyday. We always re-baseline a vehicle before a major modification and re-test in the same atmosphere after the install for accuracy and validity. Serious testing requires some control over the variables. We have installed hundereds of sets of these rockers with pretty much the same gains for over six years. We rarely hear anything negative from folks who are using them if the rockers were properly installed. We have had to re-adjust some rockers, in accordance with our strict instructions when performance issues have risen. Some installers take the install process lightly and the adjustment depth of the lifter plunger is compromised. Tony Mamo just said he uses the Crane rocker kit on his own C5. I value his experience and his opinion. I take exception, however, to his comment that Crane rockers may be too heavy and therefore induce valve float. The Crane rocker weighs 142 grams. The stock rocker weighs 137 grams. That is only 5 grams difference. Not much of an issue with a rocker arm, could be an issue if you deal in illegal substances lol. The increased weight is located primarily over the rocker stud. Furthermore, the moment of inertia is less with the Crane rocker. Another benefit is the extra leverage provided by the increased rocker ratio allows the use of lower seat pressures to control the lifter as it returns to the base circle and to control hydraulic pump-up of the lifter's inner plunger. The advantages are significant and evident and we have continually observed this during the vast amount of dyno testing we have done. Perhaps Tony was refering to the "other" aftermarket rockers. Regards, Roger Vinci. P.S. PM Joe Vinci so he can try to help you get the car back on track
As for any "good(We all know who makes the good ones)," aftermarket roller rocker increasing valve float over the stock ones. B.S. I would have to agree with Roger. The Cranes, Comps, Jesels roller rockers I have seen installed have all produced a 10-22 horsepower/torque number and more importantly across the rpm span.
07-19-2005, 09:42 PM
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also, when you had the broken valve spring, did they do a compression and leakdown test on that cylinder? maybe the valve kissed the piston just enough to slightly bend it.
07-19-2005, 09:48 PM
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ok found your post where you said this:
still suggest a leakdown to be sure.
Originally Posted by gmblack3
Took the rocker arms off of #1 so that I could put some air on the #1 piston for a leak check. Had to hold up the spring to seal off the lifter, no air leaks at all thru the intake or exhaust. So all should be well with those.
07-19-2005, 10:04 PM
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Originally Posted by mrr23
my first thought when looking at the graph suggests an initial burst knock. was there any data logging done to try and detect this? case in point, here's one of my graphs where i did back to back runs. the first one i went to start the run and it downshifted on me. so, i held the rpms up higher. unfortunately it was still in knock retard and finally gave it back in the upper rpms. as you can see on the next run, it wasn't there.
What other symptoms would I see with a slightly bent valve?
Had a few days of "hard driving" this past w/e. Everything did feel great!
07-19-2005, 10:07 PM
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maybe a slight miss. some popping through the exhaust/intake. don't remember which spring broke that held which valve. slightly rough idle. you can use a vacuum gauge to see if the needle bounces around. and indicator of an intake valve that's bent.
07-20-2005, 06:24 PM
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GMblack 3 -You very well could have other issues affecting the dyno number; especially considering the time lapse between the two. The only way to really tell is to dyno with the Cranes again, leave the car on the Dyno then reinstall the stock rockers and dyno again. A true back-to-back comparison. Either way the high cost of aftermarket rockers just doesn't seem to justify the hassle and low hp they put out.
07-20-2005, 09:19 PM
#32
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Originally Posted by DrkPhx
GMblack 3 -You very well could have other issues affecting the dyno number; especially considering the time lapse between the two. The only way to really tell is to dyno with the Cranes again, leave the car on the Dyno then reinstall the stock rockers and dyno again. A true back-to-back comparison. Either way the high cost of aftermarket rockers just doesn't seem to justify the hassle and low hp they put out.
07-21-2005, 09:22 AM
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Originally Posted by vettenuts
Sound like you feel there was a SOTP, can you elaborate on this statement?
07-26-2005, 11:08 PM
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Wanted to finish the leakdown today, but I broke the wifes car so I had to fix it. What really sucked it that I had to put everything back together without finishing the leakdown. Have wed off so hope to get it done then.
07-27-2005, 12:40 AM
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Originally Posted by mrr23
still suggest a leakdown to be sure.
I broke a valve spring a month ago and did nothing but change all the crane duals to comp cams 918s, and redynoed at the same place, and lost 8whp. And I take that to mainly the weather and the fact that I HPTune the crap out of it and Ive done alot of changes in the tune, and havent had time to WOT tune it yet.
Dixit
07-27-2005, 02:04 PM
#40
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Nothing wrong with the #1 valve or any of the others:
psi/psi
#1 90/87.5
#2 90/87
#3 90/87.5
#4 90/86.5
#5 90/85
#6 90/87.5
#7 90/87.5
#8 90/85
A difference of 5psi between cylinders is good.
A difference of 10-15psi requires futher investigation. At least thats what it says on the Mac tool case.
Car had a re-ring for oil consumption at 20k, now near 70k.
Hope to do some logging of data next month. No matter what will dyno again at the same place in the fall.
psi/psi
#1 90/87.5
#2 90/87
#3 90/87.5
#4 90/86.5
#5 90/85
#6 90/87.5
#7 90/87.5
#8 90/85
A difference of 5psi between cylinders is good.
A difference of 10-15psi requires futher investigation. At least thats what it says on the Mac tool case.
Car had a re-ring for oil consumption at 20k, now near 70k.
Hope to do some logging of data next month. No matter what will dyno again at the same place in the fall.