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Originally Posted by mike tkach
(Post 4029785)
im saying that rod length has no real difference in piston speed from a measurable difference.a few feet per second when you are talking about thousands of feet per second is not going to matter,but i did learn something,and that is that rod length can change piston speed ever so slightly.
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Originally Posted by Black Baja
(Post 4029794)
Gotcha. It was some interesting information. I've always gone with "stick the longest rod possible in the motor" and still try to have a decent ring package... I think that philosophy is starting to change now to as I've heard the pro stock guys are decking the heck out of their blocks and running very short rods. I still think for an endurance motor it is better to go with a longer rod.
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My friends at Diamond Racing did exactly that along with EXTENSIVE cyl head work, running 7500 RPM Custom pistons (made by Diamond) and did they ever sound scary on the dyno!! I'm still running those cyl heads on my 502s now. but mild short block set ups for reliability as I eluded to in past posts. Haxby's N/A set up sounds sweet!! should make Tinks Daytona fly.
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Originally Posted by MILD THUNDER
(Post 4029707)
Excellent information. I know every builder has a few favorite combinations when it comes to bore/stroke/rod length. What is yours, as far as a marine endurance build?
Also, at what point does your liking of a raised pin height, become a worry with forced induction, or does it? |
Originally Posted by HaxbySpeed
(Post 4029853)
That's a tough question. Every single build is a bunch of compromises, strength for weight, average power for peak, component quality for budget, compression for octane, etc. Even a completely optimized build is full of compromises. On the rod length / pin height deal for a forced induction marine app, absolutely, crown thickness, depth to top ring land and overall ring pack dimensions take priority. With newer piston technology and design though, it is possible to push the limits a little more. I never used to build blown 4.375 short deck combo's with anything but a 6.385 rod but, now with better piston/ring design and quality, I've had good luck with a 1.07" compression height for low boost (10# ish), so I can run a 6.535 rod if I want. To sort of answer your question; I prefer shorter stroke, short deck, big bore combos most of the time for marine blower app's. You really don't need anything bigger then a 540 - 557" deal to make 1000 - 1300ish hp
I almost bought some real short stroke shortblocks a couple years ago I thought were cool. A friend of mine had them, they were 3.875 stroke, merlin blocks, callies magnum cranks, oliver rods, 4.560 bore. I thought they would make some nice little high revving engines. They were long rodded, with big domes. I just couldn't tear two nice new setups apart to make the changes I would have needed to make them work, so I left them alone. I thought the 3.875 stroke was pretty odd when I first looked at them. |
That TR motor RM posted up looks sweet!!:party-smiley-004:
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Originally Posted by WETTE VETTE
(Post 4030002)
That TR motor RM posted up looks sweet!!:party-smiley-004:
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So if instead I went with a supercharger.
Lets say I buy a blower, intercooler and FAST fuel injection that I can put on my existing 509engine, 10 to 1 compression, crane 741? hyd. roller cam, pistons are zero decked, Pro 1 heads that were reworked by Jim Valakeo. Thinking with the compression I should be safe to run E85 even with the blower. Later I build a new bottom end that can handle much more HP and bolt my heads, blower and fuel injection to it. Will the FAST fuel injection system work well with a blower and E85? What blower would you suggest? |
M3 procharger all the way with that kinda motor. I've never ran e85 but I can tell you from being around alot of blown alcohol motors that alcohol does not get along with aluminum. If you let it sit in an aluminum pan it will eat a hole through it. I'd be afraid of it eating a hole in gas tank. And the fact that its gonna use alot more fuel also...
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Been running E85 for a couple years now, no problems eating up anything. With the right map sensor and proper tuning the Fast will do anything you want.
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