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about to dyno the s2k w/ 4.77

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Old Jun 4, 2006 | 08:32 AM
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Default about to dyno the s2k w/ 4.77

I know with a stock setup people suggest to use 4th gear, but for a 4.77 setup, should it b on 5th? Thanks for your input.
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Old Jun 4, 2006 | 08:44 AM
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I'm pretty clueless on the matter of which gear, so I won't comment. However, when you're done, I'd like to see what you get. Did you get a "pre-gear" dyno? I don't think you'll see any change in WHP, but some say that you might see a slight increase in torque with the gears.
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Old Jun 4, 2006 | 08:51 AM
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Fourth would be preferable.

The gear factor is 6.42 for 4th and 5.37 for 5th when using 4.77s. Who is doing the dyno and what type of dyno is it?
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Old Jun 4, 2006 | 08:55 AM
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not too sure what a pre-gear dyno is... i believe there r a couple of dynos in my area.. i know one is a dynojet, another a mustang... what is a pre-gear dyno?
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Old Jun 4, 2006 | 08:58 AM
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Originally Posted by AllStock27,Jun 4 2006, 09:55 AM
not too sure what a pre-gear dyno is... i believe there r a couple of dynos in my area.. i know one is a dynojet, another a mustang... what is a pre-gear dyno?
Before you installed the 4.77s.
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Old Jun 4, 2006 | 10:03 AM
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They did mine in 4th gear after I told them the 4.77's were in there.
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Old Jun 4, 2006 | 10:47 AM
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In the "old" days of 4speed top loader FORD's, 4th gear was a 1:1 ratio (mainshaft had 4th on it so it was a direct link right through the transmission). This gear had the least amount of mechanical loss, which would give you the most accurate (translated as HIGHEST!) indication of RWHP. I don't know which S2000 gear, if any, has that designed in. I think the rule of thumb of 1:1 ratio (or the closest gear to it) has just stuck.

But to make a long story short, a differential gear change would be inconsequential (mechanical losses between swapping differentials being equal), your vehicle speed would just be slower on the dyno.
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Old Jun 4, 2006 | 12:05 PM
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Originally Posted by RWD_RCKT,Jun 4 2006, 01:47 PM
In the "old" days of 4speed top loader FORD's, 4th gear was a 1:1 ratio (mainshaft had 4th on it so it was a direct link right through the transmission). This gear had the least amount of mechanical loss, which would give you the most accurate (translated as HIGHEST!) indication of RWHP. I don't know which S2000 gear, if any, has that designed in. I think the rule of thumb of 1:1 ratio (or the closest gear to it) has just stuck.

But to make a long story short, a differential gear change would be inconsequential (mechanical losses between swapping differentials being equal), your vehicle speed would just be slower on the dyno.
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Old Jun 5, 2006 | 08:53 AM
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pre-gear dyno.. ahhh im stupid. thought it was some type of dyno or something. lol but unfortunately i haven't dyno'd her yet prior the SC install.. I'm just waiting for the testpip/exhaust n i should b all set. I'll post my dyno on the FI forum as soon as i get it done, possibly sometime this week or nxt week.. just need to get the boost guage and the local exhaust shop fabricate a test pipe for me..
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Old Jun 5, 2006 | 09:02 AM
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I hope no one has the misconception that the gears will net you horsepower on a dyno...
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