I have a 1970 Chevelle SS with a 489 cu-in big block. I ran a best time of 10.99 @ 124.25 mph. Recently I noticed that my car has dropped off in mph and ET to 11.10 @ 122 mph. I did a rear wheel dyno that produced 480 hp but my engine dyno made 680 hp? Does 200 hp loss seem excessive? In either case I bought a new 9.5 inch Dynamic converter and will be rebuilding my Turbo 400. The transmission oil is dark in color and has little gritty particles in it. I currently have a 10 TCI super street fighter converter. What is a reasonable hp loss from motor to rear wheels.

Tino

What foot and flash stall are you getting with the TCI converter?

I would say about 2,900 foot and about 4,000 rpm flash.

Tino

You can't compare those dynos,,two different animals. You say you lost 1/10th of a second? That could easily be weather conditions. Was the 60ft time the same?

The 10.99 pass was 1.652 with a 99.29 mph at the 1000 ft mark. The 11.104 pass was 1.631 with a 81.68 mph at the 1000 ft mark.

With the 60 speeding up and the 1000 slowing, I would say tuning and or weather. Did you make one pass or were they all in the low 11's? The track I race at runs at night and there can be hot and cold spots of air that screw with the e.t. big time.

I made quite a few and they were all low 11's with one turning a 98.20 mph at the 1000 foot mark with a 1.648 60 ft time. the mph at the quarter mile dropped to 120.85 ... weird. It was a crazy day???

:confused: I'm running 101-102 mph at the 1000ft. mark....something is not right here :confused: I only run high 11's low 12's in the 1/4 mile...my mph in the 1/4 is 111-113 :confused: maybe those are 1/8 mile mph's???

200 hp less seems a bit excessive.My sbc hit 406 at the wheels but never dyno'd just motor.automatics lose more hp than manuel trans