Is it possible to run a 6.125 rod length to increase stroke and displacment? I am looking to find the best configuration to get mid-range torque for the street. Would I find better mid-range torque from a larger stroke crank and short rod? The car will more than likely be a week warrior not a daily driver. Another question I have is about the heads. I have read that the stock (p&p) heads on the LT1 will achieve about the same rwhp numbers on both a 355 and a 383, 396 given same top end. Is there another setup between the 355 and 383 (ie. 377) that will take full advantage of the heads?

 

The effect of differences in rod length are trivial except in the context of an all-out race motor whjere everything is optimized to work together toward a narrow goal (e.g. "max power from 5,000-8,000rpm"). With the same heads and cam the stroker will make just a little more hp and torque and will do it a couple hundred rpm lower.

Rich

 

Thanks rskrause for the reply. I am looking to make power between 2500-6500 range. I found a set of rods that are 6.125 in length and was curious about an odd ball setup (ie. 6.125 rods, 3.48 crank, .30 over pistons). I am planning on driving the car mostly during the weekends. I would like to spray a sizable amount of nitrous (150-250) shot. My primary goal for the car is high 10s - low 11s on motor without weight reduction. Also I would like to keep the engine pump gas (93) friendly off the nitrous.

Thanks
Cody

 

Well, your compression heigth with that combo will be ok even with the long rod, due to the short stroke. But it will be an oddball combo and may therefore be tough to find appropriate psitons for. You may need a piston with a custom CH.

Rich

 

Again thanks for the help. Is there some kind of calculator to determine the appropriate CH height needed? Also would there be any real gain with going a 3.50 stroke crank over the 3.48?

Thanks
Cody

 

Take half the stoke + rod length and subtract from the deck height.

Take for example a stock sbc with 5.7 rods. 3.48(stroke)/2= 1.74

1.74+5.7(rod length)=7.44

9" (deck height) -7.44= 1.56" CH

Actually deck height on an untouched block is in the neighborhood of 9.025" but shelf sbc/LT1 piston compression heights are figured based on a 9" or zero deck. Any extra you may have is the distance your piston is "down in the hole" No gain in the 3.5 vs. the 3.48 but the difference in stroke will allow you to run a shelf piston with a 1.125 CH.

 

circle trackers like sprint cars and late model modifieds like those long rod setups
swap meets would be a good place too look for odd ball pistions or get ideas from those racers on their SBC setups

i always thought that a long rod like a 6.125" would move the wrist pin too far up in the piston and not leave enuf meat on top especially when spraying it....

 

I don't know if this will mean anything as the thread was from 3 months ago but I saw a JE piston that would suit a 3.5 stroke with 6.125 rods.http://store.summitracing.com/defaul...=egnsearch.asp
The Part #JEP-181911-8