Open Deck Block
 

It has just been released that the frs/brz will have an open deck block. How does this change your plans for modifications? How does it change the expected HP gains from bolt ons? And please explain in layman terms :happy0180:. The reason for this thread is I have seen people state they need to change their plans a bit now that this has been released.

edit: dont spam "i dont care" if you simply dont care then please dont post. I would like info regarding this not because I am concerned about HP gains (because I am keeping my car stock) but more out of curiosity from the minds of those whom planned to do some mods to their car (seriously expensive or relatively inexpensive). I am not a tuner so I would like to hear from them. Just for my own curiosity and my desire to gain knowledge. Its a discussion and not one to be had with people stating 'I dont give a F*&#" because that doesnt benefit me or the readers. THANKS ^_^

I'm autocrossing, not a fuck is given.

the 2AZ-FE is open deck and i have seen big power made and have pushed 400 myself on a stock block so really i could care less. plus if there are problems ERL and Darton will release sleeves in a matter of time.

^ I dont think you can compare a boxer four to an inline 4 in terms of hp gain. can you? I see that the bore n stroke are the same though. How about somebody explain the difference between open deck blocked or semi open? or closed? not too sure.

^^^ SAME.

Do you know what SCCA stock class we will fall into? S2Ks run BS, but Miatas with 1.8L run CS... i haz a confuzion :iono:

ok dont thread jack thanks.

I believe open deck vs closed deck refers to the block. If you look at the top (or side, in this case) of the bare block, looking down the cylinders, the area around the cylinders will be "hollow" or open. This could potentially cause an issue if you run crazy high boost pressures, there is a lack of reinforcement that a "closed" deck might offer. The thing that slightly concerns me is heat dissipation... so many miles and heat cycles, I wonder how round they remain over the years.

Maybe someone else could chime in? I think Im on the right track, but not sure.

/unintentional thread jack

open deck is fine. i believe GM tested their stock ecotec block for import drag racing and failures only occurred after 500+ hp or something like that.

As above. Open deck only becomes an issue with big cylinder pressures. And there will be plenty of aftermarket solutions for people chasing those big pressure/power numbers. There are tons of big power modified open deck motors out there.

This seems pretty relevant
http://legacycentral.org/library/literature/deck.htm

pistons exert force on the sidewalls of your cylinders as they travel up and down (or left and right in our case)

if this force is great enough, then the cylinders begin to deform/warp/move


as a visual example, take an empty toilet paper roll and hold it up in the air and put your finger inside and move it up and down along the wall without applying too much pressure.

nothign right?

now apply lots of pressure and see your cylinder turn into an oval.

this is not good, because now your pistons are not sealing, pressure is lost, oil gets into places where it's not supposed to, all a big mess, next thing you know and BOOOM

a closed deck is just a cylinder designed with reinforcements... which are only necessary if the cylinder is weak to begin with

if your toilet paper roll was made out of solid steel, no amount of pressure from your finger would deform it!


however much the stock FT86 engine will hold will be determined once it's out.

This is going to end up being a non-issue for the vast majority of owners.

I'll hazard a guess that most owners will limit their engine modifications to "bolt-ons" like intake, header, exhaust, and ECU tune. Open deck isn't going to make a bit of difference for them.

Even aftermarket bolt-on turbo/supercharger kits won't be bothered with the open deck as the static CR will likely be the limiting factor.

The only people that will likely ever care or notice the open deck are those pushing double-ish stock HP level.

At which point you would consider sleeving the cylinders anyways correct?

i'd put in a different engine all together...

you have to define what you want to do,

do you want to make a point and build up X engine to make Y power

or do you just need Y power and don't want to worry about anything else?

drop in a straight 6 from a supra or something and call it a day.