Which is better? Short deck or tall Deck block

[2wolf_Michael]

I am trying to work out parts for my engine build.



Here is the plan so far.

RHS block
K1 4.250" Stoker crankshaft
K1 Rods
Wiseco 4.165" bore pistons
PRC LS7 based heads
Kinsler * stack ITB intake system


My question is would I be better off going with the short deck or tall deck block and why?
I know the tall deck version will use longer rods, they have options for either set-up.

I am not looking for real high HP numbers, but more looking for better torque. As the engine will be in a Lotus 7 based car with T-56 trans.

If you need any more info and I can give what I know so far.

I am just not sure which will be a better set-up.

[ChevelleNV]

Well I have a similar build.

4.250 Crank
6.25 Long Rod
and a 1.315 Pin height piston. the reason I went with a Tall deck was to get a decent pin height and skirt length in the piston, and run a longer rod length.

what pistons (pin height) and rod length are you running?

[2wolf_Michael]

For the Wiseco Pistons for the 4.750" tall deck block.
Part # K452x165
4.165" bore, 1.110 Comp Ht., 4.250" Stroke, 6.477" for K1 Rod length,0 deck at 9.712", STD deck will be 9.715". 446 gram average weight, -20cc volume, which should give me close to 10.1:1 Comression ratio. This is the information give in the PDF I downloaded from there website

Part # for there rods is CH6477ALLBLS-ST8-A
Part # for there crnkshaft is 346-4250RB6F-58, with 58 tooth reluctor ring.

This along with the PRC LS7 285cc CNC ported and polished heads and my Kinsler ITB set-up is what I am planning on running.

I had picked the ITB set-up up for a LS7 441 stroker motor I was planning on ordering, but it had a LSX block.

Not sure if this is what you are talking about. But this is the info I have right now.

[ChevelleNV]

a 6.477" rod? that's an odd size...

My self I would use a little bit shorter rod and a little bit taller pin height on the piston. but based on your combo you will have to run a tall deck block. Stroker motors like the long rods so I would stay away from running a short rod with that long of stroke to squeeze that combo in to a std deck block. that long stroke combo will be much happier in a tall deck. which by the way has a nice 1.52 rod ratio with that 6.477 length rod.

Any idea which block you are planning on using? Myself I bought a LSX bowtie (they come 9.720 semi finished) and I decked mine to 9.695. keep in mind the LSX tall decks are semi finished blocks, so you will have to spend an additional 1000/1200 at the machine shop to get it ready to roll. Of course when i bought mine there were not to many aftermarket tall deck aluminum blocks out yet. I would seriously consider a different block now if this one wasn't already all machined up and ready to be put together.

if it helps you out my full combo is 441 cubic inches

4.250 Crank
6.250 Rod
4.065 bore
1.315 Pin Height
9.695 with piston .005 in the hole.

10.5:1 Compression Ratio with Ported L92 heads

[howehot]

I've been told the tall deck is better. With the short deck they have a tendency to pull the piston farther out of the bottom of the cylinder. This will cause piston wear and oil use.

[2wolf_Michael]

Yes 6.447" is an odd length, this is for with a K1 Tech rod or you can go with a 6.500" for a different brand. Yess these are the specs for the RHS tall block set- up they listed. Tjey do have a rod option for a short deck option also. With the intake I am using I do not have to use or worry about the filler plates for the heads with the tall block, since it is a 3 piece design and each side is separate, plus the valley plate, a Kinsler 8 Stack ITB system with Reveire CF plenums that have 3" adel clamps to hookup to the cold air intake/ air filters.
I am going to get the block, heads, crank, rods and pistons ordered on Monday. Then start to spwc out the rest of the parts.

[2wolf_Michael]

Here is Wesico Pistons PDF I used for the specs.
I went by the LS 4.750" Deck and the next to bottom set of pistons and then the rods and crankshaft listed at the bottom of that list for part numbers. I have found all of these parts at a good price so I will be ordering them in the morning, along with a comp cams timing chain and other odds and ends.

Along with a RHS Tall Deck block with 4.165" finished bore block and a pair of PRC 285cc, CNC ported and polished head.

I already have Kinsler LS7 Sprint style ITB intake with 2 5/8" bore throttle bodies intake.

From here I stil need to find a camshaft and valvetrain, I am calling Kinsler to find out there recommendation for the cam also, so I can have a good base to start with.

So this will give me 463CID or 7.9L stroker.
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