Surprisingly high RPM in chip test.

[Larry S.]

Jason,
I see you have 4.10s in your truck but your RPM at 65 mph are considerably higher than I experience with my 95 with 4.10s and stock tires. I turn about 2800 in direct drive, 3rd for me, at 65. Any idea why the difference?

I disagree that the dyno was much more severe than seen in towing. I typically tow with cruise engaged and when I hit a steep climb I often let her pull down until EGT gets too high or cruise drops out. With my chip it won't drop down a gear unless I tell it to. That kind of loading should be very similar to your dyno loading. Your real life tests will be very interesting.

Keep at it, you're doing a great job.

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95 F-250 SC, 4x4, E4OD, 4.10, Tweaks by Hypermax, Xcelerator filter, Front add-a-leaf, Firestone Ride Rite, Hellwig rear sway bar, KYBs, Milemarker hubs, EGT and Boost gauges, Turbo-Trac, Century topper and 24 ft Nomad Fifth w/slide. If you don't care where you are, you ain't lost.
Larry

[Mark Craig]

Larry S,
Check your tire size, most SRW trucks have 265 instead of 235's.
Mark

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Mark Craig Western Diesel Performance 1-888-621-4006 2000 Crew Cab Dually, 6 speed, 4.10 Limited Slip, Lariat. Toys are Turbo Brake, Turbo Chip, Turbo Gauges A-Pillar Mount, Turbo Foam Air Filter.

[Larry S.]

Nope, I have 235/85 16s. I think the 265s didn't come until the Super Duties. I've checked the calibration of my speedometer and my tach vs. speed matches several others with the same model truck as mine. I've run at 75 in 3rd with a bit more left before hitting the limiter. My limiter kicks in between 3300 and 3400.

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95 F-250 SC, 4x4, E4OD, 4.10, Tweaks by Hypermax, Xcelerator filter, Front add-a-leaf, Firestone Ride Rite, Hellwig rear sway bar, KYBs, Milemarker hubs, EGT and Boost gauges, Turbo-Trac, Century topper and 24 ft Nomad Fifth w/slide. If you don't care where you are, you ain't lost.
Larry

[kreynol2]

My RPMs at 65 in direct are about 2800. I have an automatic and when pulling a big, steep hill, the tranny sometimes drops out of cruise. I put it at about 65 or so and that's 2800 or thereabouts for me.

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Kevin

[This message has been edited by kreynol2 (edited 01-31-2001).]