496 CMI Sport Tube dyno test
06-02-2009 | 10:40 AM
#1
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From: Spicewood, Texas USA
496 CMI Sport Tube dyno test
I finally got a chance to dyno a set of CMI headers on the prop shaft dyno. These were installed on a twin engine Formula with captains call exhaust. The install was a lot of work. We had to cut the diverters significantly to get it to fit. The kit also included brackets to relocate the pcm, fuel pump module and oil filter. That was all pretty straight forward. The hatch lift didn't clear the headers and needed to be relocated. I'm attaching the dyno sheets. They were run using standard correction method.
06-02-2009 | 11:01 AM
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From: Lake Conroe, TX.
I finally got a chance to dyno a set of CMI headers on the prop shaft dyno. These were installed on a twin engine Formula with captains call exhaust. The install was a lot of work. We had to cut the diverters significantly to get it to fit. The kit also included brackets to relocate the pcm, fuel pump module and oil filter. That was all pretty straight forward. The hatch lift didn't clear the headers and needed to be relocated. I'm attaching the dyno sheets. They were run using standard correction method.
06-02-2009 | 05:32 PM
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From: Missouri
I finally got a chance to dyno a set of CMI headers on the prop shaft dyno. These were installed on a twin engine Formula with captains call exhaust. The install was a lot of work. We had to cut the diverters significantly to get it to fit. The kit also included brackets to relocate the pcm, fuel pump module and oil filter. That was all pretty straight forward. The hatch lift didn't clear the headers and needed to be relocated. I'm attaching the dyno sheets. They were run using standard correction method.
06-02-2009 | 06:57 PM
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From: Spicewood, Texas USA
Read the charts closer...stock made 395.6 at 4800 and the cmi made 419.6 at 5000. That's only 24 peak hp but it did move peak hp up a couple of hundred. So maybe if the engine was turning higher Rpm the gain would have been a lot more. hmmmm.
06-02-2009 | 08:00 PM
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From: sint maarten
think i would like to see the raw data including the inlet air temp and oil temps , hunidity and the uncorrected numbers before i was willing to buy into this increase.
20 deg of oil temp will make a huge dif in the actual and true power made and minor differences in the runs between the inlet air temp and the humidity will make the correction factors significantly different.
not saying you are wrong... only pointing out that if you are doing this sort of comparison and want the litteral truth at the end, then a good dyno operator will make sure that the run parameters are as close to identical as possible and even then will do several runs with each configuration and average the results...
thats why the uncorrected numbers are always best. if the run conditions are the same then the uncorrected numbers are the truth. if the run parameters are different in any meaningful sense, then the correction can easily lead you to believe somthing that is a lot less accurate.
20 deg of oil temp will make a huge dif in the actual and true power made and minor differences in the runs between the inlet air temp and the humidity will make the correction factors significantly different.
not saying you are wrong... only pointing out that if you are doing this sort of comparison and want the litteral truth at the end, then a good dyno operator will make sure that the run parameters are as close to identical as possible and even then will do several runs with each configuration and average the results...
thats why the uncorrected numbers are always best. if the run conditions are the same then the uncorrected numbers are the truth. if the run parameters are different in any meaningful sense, then the correction can easily lead you to believe somthing that is a lot less accurate.
06-02-2009 | 09:10 PM
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From: Missouri
Well then that is only , what, 3 hp more (at the crank/dry exhaust) than the lightening headers showed you earlier and ditto versus the Dana IV's wet/prop shaft. Mith Busters rejoice. I know I am. Bob you are the King!!
06-02-2009 | 09:32 PM
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From: Lake Conroe, TX.
Interesting.
