360ci std vs big bore short stroke

[fastlam12]

Building a 360 ci. 2bbl. Is a bbss better on a tight track ? Running in a b mod class. Also is it good to do in a stock 400 block ? And would you use 200 runners ?

[ford396]

In my opinion, if you are building a new bbss engine:

Put it in an aftermarket block. It is an insurance policy.

These motors like rpm and you need to look at keeping rotating weight to a minimum and use good valve train parts for the rpm needed.

Depending on the quality of parts and rpm able to be run, I would use a little bigger head. I have this setup with 215 heads and it is not lazy anywhere and runs great on the track. I also had a 14 degree engine like this: awesome.

Different people will have different opinions on this subject and ultimately, you will need to decide.

Good luck.

[50j]

An advantage of the larger bore is more room between the cylinder wall and valve so flow is better. The down side may be the block.

[stock car driver]

2 barrel carb.. max 200cc runners. oem vortecs would be better than dart or other aftermarket 200s with a 2 barrel. vortec bowties are better yet.

Id build a normal 360 not a short stroke big bore with a 2 barrel. Still using as light of parts as you can afford. Including tool steel 55 gram lifters, hollow intake valves etc.

big bore short stroke motors have very little torque and need an extra 1000 rpm or so, which your 2 barrel wont flow.

[TBRE]

True....and most stock classes don't let you fool with the chamber to accommodate the larger bore anyway.TB

[let-r-eat]

I have two 12oz glasses. One is 6 inches tall and the other is 1 inch tall.

Which one holds more water?

Which one can I fill faster?

[englertracing]

lre is right
people think the bbss motors lack the torque
they are fear mongers
the displacement is the same

but guess what, the bbss motor cuts down on friction and allows for less valve shrouding
there may be minor torque differences from the fact that the bbss motor uses as long or longer rods than the standard motor

id go bbss any day, make sure you use the thinnest rings you can get your grubby hands on,
sending pistons to rebco machine for
verticle gas ports (methanol motors only)
lateral gas ports (gas engines)
is a great idea.
or you can order them that way from je/cp/whoever

[fastford]

torque is some what considered leverage, a longer pry bar can lift the same load easier than a short pry bar, ie:crank pin center in relation to main center or stroke . if I were limited to a 2 brl carb, which normally means 6500rpms, I would go with longer stroke. now you start adding 4brl tricked out carbs and big heads with the valves stood up and turning8000 plus rpm,s , and the ssbb is better. your rules really determine what is best, JMO....

[englertracing]

torque is some what considered leverage, a longer pry bar can lift the same load easier than a short pry bar, ie:crank pin center in relation to main center or stroke . if I were limited to a 2 brl carb, which normally means 6500rpms, I would go with longer stroke. now you start adding 4brl tricked out carbs and big heads with the valves stood up and turning8000 plus rpm,s , and the ssbb is better. your rules really determine what is best, JMO....

What crank angle does peak pressure occur at?
It is long before the rod and crank throw reach 90 degrees.
This minimizes the effect your speaking of

[TBRE]

Look at our web, we gas port pistons, as well as compression balance grooves to go along with them.
...www.tonybarkerracingengines.com......

[englertracing]

Look at our web, we gas port pistons, as well as compression balance grooves to go along with them.
...www.tonybarkerracingengines.com......

How much do you charge?
Rebco has 6 mills setup just for piston operations

[TBRE]

Same as the piston companies do, $15.00 per piston, and $6.00 for CB groove.TB

[perfconn]

Compression balance groove? Thats a new term to me.I have heard of an accumulater groove.Is that what you are referring too?

[TBRE]

No, it's a groove around the top of the ring land connecting the gas ports.TB

[TBRE]

The only drawback to running lateral gas ports is when the piston rocks, it tries to shut off the thrust sides from the cylinder pressure, this fixes that, and obviously helps keep the piston "centered" in the bore.TB

[latemodels4life]

I know back here in Pa. at a certain track both big bore and std. bore motor's are winning at the same track, they both seen to run great on heavy or slick track. this is in a limited 358 late class.

[fastford]

What crank angle does peak pressure occur at?
It is long before the rod and crank throw reach 90 degrees.
This minimizes the effect your speaking of

so your saying a 3.25 stroke will produce more torque than a 3.500 stroke at 6000rpms?

[TBRE]

Perfconn, look on tonybarkerracingengines facebook page, there's a picture of a Mahle Power Pack with those options done to it.TB

[turtle1hp]

Both motors build similar torque curves when built like for like. (compression, cam, heads, intake and carb restrictions) If you are going to put the largest intake valve in the head that will not hit the exhaust valve, then it would be an advantage to open the combustion chamber to the larger bore, to unshroud the valve for more flow. Then you now have the larger surface area of the piston in which the combustion pushes down on. Example: 4.125" bore is 6.47 sq. in. surface area vs 4" bore is 6.28 sq. in surface area. We will just use 1500 psi as our combustion pressure. 1500 x 6.47=9705 psi pushing down on the connecting rod vs 1500 x 6.28=9420 psi pushing down on the connecting rod. Now add the shorter stroke crank and you can have a lighter rotating weight with the even smaller moment of inertia. (the weight is closer to the centerline of the crank) This also aids in the acceleration rate of the given torque applied to the crank itself. But this combination requires different cam timing intervals to aid in the cylinder filling process. The lower piston speeds from the shorter stroke and the rod length have to be taken into consideration when designing the cam. If you have deep pockets, it has its advantages and the dollar figure to go along with it. The amount of extra money spent for the these is questionable. Sometimes it is smarter to keep it simple and spend the money on fresh tires. BUT.... That is just my humble opinion....