540 CI advice needed

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540 CI advice needed

Post  Petersonpulling on August 13th 2016, 7:45 am

I am into truck pulling and am going to be running a class with a 540 CI limit. I have the goal of 950 horsepower. My heads are trickflow a460 340's that have been ported some. Not sure who did the work or what flow numbers are, but intend to send them out and have them flowed. I am going to run an eliminator block. Without getting into all the specifications, my question is..... What would be better? A 4.500 stroke and smaller piston size, a 4.300 stroke and slightly larger piston, or a 4.140 stroke and a coffee can sized piston. I'm not as worried about torque coming off the line because I am running a slipper clutch and I can come out at high rpm. My concern is I want the engine to maintain rpm when the weight comes on and at the end of the track. But I'm also looking to turn 8500 rpms reliably. Gearing and tire size comes into play as well, but I'm just looking for general advice on the engine right now. Thanks!

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Which bore/stroke combination?

Post  DanE on August 13th 2016, 9:03 am

A 4.56" bore and a 4.14" stroke (6.8" rod and a 1.43" CH piston, R/S ratio of 1.64)  produces 540.89 cubic inches. If there is no leeway on the 540" limit, one could offset grind the crank a touch to get under the 540" limit. The 4.14" stroke results in better rod angularity than the longer strokes and therefore less internal friction at the higher RPMs and the larger bore allows better valve breathing. Torque is a result of displacement, not stroke length.

OR, you could use a 4.625" bore and a 4" stroke for 537.6"s with a 7.1" rod and a 1.2 CH piston for a R/S ratio of 1.775.

On an engine that is going to pull 8500 RPMs over an extended period of time, I believe a larger bore and a shorter stroke would be more reliable  and make more power.

What is the intake manifold rule?

Just a thought to get this thread going.

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Re: 540 CI advice needed

Post  Lem Evans on August 13th 2016, 11:16 am

Lunati has a 4.160" crankshaft.

4.530" X 4.160" = 536.38 It'll leave you room for a rebuild and still be legal.

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Re: 540 CI advice needed

Post  rmcomprandy on August 13th 2016, 2:33 pm

Lem Evans wrote:Lunati has a 4.160" crankshaft.

4.530" X 4.160" = 536.38  It'll leave you room for a rebuild and still be legal.

That sounds like a great combination to me for an aftermarket block build staying around or above 8,000 and higher if you have titanium valves with whatever else is needed.

I have built a couple "filled" D9TE block 540's using "A" heads with steel valves for pulling which were 4.470" bore and 4.300" stroke.

EDIT:  There is one of these short blocks going together right now but, for SCJ heads.

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Re: 540 CI advice needed

Post  Petersonpulling on August 13th 2016, 9:36 pm

DanE wrote:A 4.56" bore and a 4.14" stroke (6.8" rod and a 1.43" CH piston, R/S ratio of 1.64)  produces 540.89 cubic inches. If there is no leeway on the 540" limit, one could offset grind the crank a touch to get under the 540" limit. The 4.14" stroke results in better rod angularity than the longer strokes and therefore less internal friction at the higher RPMs and the larger bore allows better valve breathing. Torque is a result of displacement, not stroke length.

OR, you could use a 4.625" bore and a 4" stroke for 537.6"s with a 7.1" rod and a 1.2 CH piston for a R/S ratio of 1.775.

On an engine that is going to pull 8500 RPMs over an extended period of time, I believe a larger bore and a shorter stroke would be more reliable  and make more power.

What is the intake manifold rule?

Just a thought to get this thread going.

No tunnel rams, single carb no size restrictions.  I have a trickflow single plane port matched to the heads with plenum work done also. Pic attached


Last edited by Petersonpulling on August 14th 2016, 8:23 am; edited 1 time in total

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Re: 540 CI advice needed

Post  Petersonpulling on August 13th 2016, 9:42 pm

Lem, that sounds like a good combo.


Rmcomprandy, I have a set of titanium intake valves for the heads, ultra pro Magnum rockers and girdles. Engine will only turn those rpms 300 feet at a time.

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Re: 540 CI advice needed

Post  Straubtech on August 15th 2016, 3:39 pm

For that kind of peak RPM you will want the 4.140 to 4.200" stroke. Flow numbers on heads will have to be known.

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