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Discussion Starter #1
this was a 347 pro comp 205 heads, trickflow cam .565 lift in a 1994 ext cab ford ranger. with the junk pro comp heads best pass was a [email protected] mph. the truck was 3280. i have a chart thing and it say that it would be about 288 hp to tires. the motor got hot so i took it apart and found the heads was trash. i went to a solid roller .675 lift cam, dart pro 1 non ported heads. the motor made [email protected] on a engine dyno. this is a stock block with a main cap support,h beam rods,4340 steel crank,around 12.5 comp
 

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Discussion Starter #5
it was around 90 degrees on this day when we was at the track. the great state of Texas. I think it will run better when it cools off. the slower pass was shifting it at 6000 rpms we raised the shift light to 6500 and it did the faster time. the 430 gear is great for the track going thru the light at 6500

 

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Think it'd hold together for a 6900-7000 rpm shift?

Exact shift point depends on gearing, traction, etc, but as a general rule, shifting 400-500 rpm above peak HP RPM usually works well

I will say though, I have seen many big block cars run quicker times by shifting 1-2 early (near peak HP RPM), and then 2-3 at the higher RPM, but you never know until you try it.

Good work, another comment, a recording tach is a real nice thing to diagnose a run, or even a go-pro pointed at the gauges. My guy usually takes a few hundred RPM to move the lever after the light lights up
 

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I agree. Twist her on up.

Got a customer that runs an '86 Fox body in an 1/8th mile 7.50 index class. He runs a 4.30 gear with a TKO 500. Engine made around 480 hp @ 6500 on the engine dyno with a leaky old 650 Demon carb. I imagine he's making close to 500 now with a Quick Fuel Q-750.

That car will run high 10.90's if he stays in the gas and makes a 1/4 mile pass. He launches at 5500 and shifts at 7000.

Car is very consistent, he was #1 qualifier last weekend at Nashville with a 7.501. Lost very last round by a thousandth of a second....
 

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A stock block with that much hp and compression would make me nervous to twist up much higher than that but I agree it would likely run quicker. ;) Your trap speed seems very low though for that much power. Did you stay in the throttle right through the finish line? Did it feel like it was nosing over?
 

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Discussion Starter #10
the motor seem to still pulling better at the higher rpm. we are going to stop it at 6500 rpm. the truck don't carry mph 12.50s @101 mph is very low. it was like 3280 on the scales with driver
 

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the motor seem to still pulling better at the higher rpm. we are going to stop it at 6500 rpm. the truck don't carry mph 12.50s @101 mph is very low. it was like 3280 on the scales with driver
I don't understand what you mean the truck don't carry speed? The mph is generally what shows you how much power you are making. Your ET is how efficiently you are using that power.
 

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Well if you shift at the HP peak, you are slightly overcammed for the way you want to drive it

Regardless, I do think you are trapping slow for a 500 hp motor. I would check what could be different since the dyno.

Is the throttle opening all the way the way you drive it? Air filter choking it? fuel supply hanging in there?
 

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Discussion Starter #14
on the dyno we had 7 psi fuel pressure and we had 2 lines going to the carburetor. I checked it the other day after the track and we had about 6.5 fuel pressure. I raised it to 7 psi but it is one line going to the carburetor. I think its running line but some people think it is ok. I'm thinking of doing a A/f so I can see what its doing.
DLG-1 Dual Lambda Gauge

 

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What was the temperature like on the day you dynode it? Also what transmission are you running? Like Iowan said your trap speed and weight suggest you have lost some power compared to your dyno results at the crank. Could be you dynoed in cooler weather, could be trans is inefficient (C-6) or something else. If you can find the lost power it seems you have enough power to meet your goals.
 

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Discussion Starter #20
went to the track Friday and it did a faster time [email protected] mph but the tail shaft housing broke at the end of the pass. I'm going to look at it and see what the problem is and fix it. then sell the truck.
 
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