Gm short deck block

[perfconn]

Thinking outside the box.Wanting to build a light weight SAS Spec engine.The block only has a 8.325 deck height so it should be considerably lighter than a regular GM Bowtie block.My question for the experienced engine builders is: since I would have to run a 3.25 stroke and 5.7 rods,would the engine make as much power as my convential SAS Spec engines with 3.27 stroke and 6inch rods?

[stockcar5]

with a 1.75 rod/stroke ratio i think you will be fine. look at pro stocks with there short deck blocks..they run even less rod/stroke ratio. shorter deck=better valvetrain control which imo is more beneficial than a small gain in rod/stroke ratio. also as you said the lighter weight is a plus.

[perfconn]

Shorter deck =better valve train control? ????????

[sj valley dave]

I know that the 500" Pro Stock cars have gone to a short deck, real big bore, short stroke and short rod deal for the last few years. Better valvetrain control with shorter pushrods and also better intake manifold to intake port alignment for more power...

[TBRE]

short deck

The 347 8.200 SUPR engine is illegal for reasons stated above, and it only uses a 5.400 rod.TB

[perfconn]

Tony,
Thanks for replying.The short deck block isn't legal for the SUPR Spec but it is for the SAS Spec.My concern is whether the lighter front end weight would offset the slight power loss with the shorter rods.I know it would be very expensive to build since the head bolt holes would have to be drilled and taped and a BB Chevy waterpump has to be used.
Terry

[TBRE]

nuts.....

Call me crazy, but I think the benefits will outway the shorter rod. I think it will make MORE power.TB


P.S. EVERYTIME we've short decked an engine, from a taller one, the results were WAY better, even though it is a pain in the butt to accomplish it, I feel like it's still worth it. And the rod length difference, ONLY shows up on the dyno 90% of the time.

[sj valley dave]

I totally agree with TB...I think the probability exists that Perfconn will pick up HP, not loose it...The old adage of long rod=more power in all cases has really changed with the new head technology. A lot of experts think that it was that way for a long time due to lazy and ineffecient head designs that dated back into the 60's when Smokey wrote his bible...

[perfconn]

Thanks everyone for your answers even though most don't apply.We aren't talking about aluminum big block drag racing or 3600 pound stock cars.I am also not trying to make more power since my current combinations have won a $10,000 race,several $5,000 races and more $3,000 races than I can count.I just wondered if losing the front end weight would outweigh losing a little power,even though as Tony suggested I might actually gain some.

[stockcar5]

I am also not trying to make more power

first time i've ever heard that on a racing forum..lol i knew the saleman would come out sooner or later.

darn there goes my first new years resoulution to be nice to stupid people

[let-r-eat]

I've run 3.7 stroke on that deck height. Build the inches in the shorter deck height and let it roll. Good piston you like and let the rod length fall where it may. You could run the CH clear down to .860. I wouldn't fret 1 bit.