360 stroker how much HP is picked up if everything else stays the same?

[273]

Wouldn't matter if bigger bore has more fiction, up side of displacement through bore size out ways negatives when building power. Why I don't get the 408 trend, i'd even rather build the lowly 383 over a 408.

 

[justinp61]

Wouldn't matter if bigger bore has more fiction, up side of displacement through bore size out ways negatives when building power. Why I don't get the 408 trend, i'd even rather build the lowly 383 over a 408.

You're an engineer?

 

[273]

You're an engineer?

Nope

 

[Bewy]

I did some maths too. 400 Chev 4.126 bore, 3.75 stroke. 400 Ch 4.34 bore 3.38 stroke. One long, one short....stroke.
Piston ring contact area for both. Used 1/16" for both comp rings & 0.025" for each oil ring rail. A popular combo.
Swept area for Chev is 8.75 Sq in, 8.77 for the Chev. The reason they are not equal, but very close, is because the B & S of each to not calculate to exactly the same number.

Piston friction. With the larger bore, you have a wider thrust face on the piston, but it travels less distance [ shorter stroke ]. And vice versa for the smaller bore.
As I said earlier, I doubt there is much difference between the two, when all the variables are taken into account. There ARE a lot of variables such as piston skirt design, friction coatings etc, but if these differ between the two engines, then it is not an apples to apples comparison.

 

[pittsburghracer]

You guys think so hard I get a damn headache. Cut it out. Lol.

 

[fishmens67]

You guys think so hard I get a damn headache. Cut it out. Lol.

Why don't you go build another 340 and show them how it's done.
I know it's been a while since you tinkered with a 340 short block.
You spent 40 years getting the top end figured out, so I think it would be a great project for you to finish out.
The world's most powerful N/A 340.
I don't want to hear about money, I'm good at spending others.

 

[pittsburghracer]

Why don't you go build another 340 and show them how it's done.
I know it's been a while since you tinkered with a 340 short block.
You spent 40 years getting the top end figured out, so I think it would be a great project for you to finish out.
The world's most powerful N/A 340.
I don't want to hear about money, I'm good at spending others.

I sold off all of my 340’s and replaced them with 50 dollar 360’s. You know those junkyard sled motors. And I already said how fast it went but I have another 360 shortblock for my son that will probably run 6.30-6.40’s I’m guessing at 3200 pounds.

 

[rumblefish360]

Wouldn't matter if bigger bore has more fiction, up side of displacement through bore size out ways negatives when building power. Why I don't get the 408 trend, i'd even rather build the lowly 383 over a 408.

While there maybe merit to the various ways of looking at this, the bottom line is cubic inch displacement rules the day. Then there’s that vs expense.

I myself like a big bore short stroke engine coupled with the ability to rpm high.

If the cost was the same, I’d do the 408 over the 383.
Between a B vs an LA, the B would be the winner but how does it play out in the car?

Once again, everything is build target dependent.
AKA - What are we doing with what?

You're an engineer?

You’d think that right!

 

[pittsburghracer]

I think it’s was this post that someone mentioned valve to bore size for shrouding. I’ll just mention that my 2.08 valve size Edelbrock heads and my bigger yet 360-1 Indy heads are flow tested on a 4.015 bore adapter.

 

[Bakerlite]

Piston friction. With the larger bore, you have a wider thrust face on the piston, but it travels less distance

Do you think the same side loading, but on a wider piston skirt creates more friction? Like, spreading the load over a wider area?

 

[Bewy]

The greater the contact area, the greater the friction. If the R/S ratio is the same for each engine, I think there would be bugger-all [ A good old Aussie term that you would know! ] difference in frictional losses. Overall, my point was/is that the difference in friction losses for the combos we have been discussing is minimal.

 

[pittsburghracer]

Since you guys are going over the edge let’s calculate these factors.

what effect does piston coating have. There’s gotta be a reason for it.

let’s calculate the difference between 10-30 oil, 10-40, 20-50, 40 weight, and 50.


How about lead free fuel, racing gas, E85, and alcohol.

spring, summer, and fall racing temps.


How about shift rpm’s. 5700, 6200, 6500, 6700, 7000, and 7500. Feel free to add any other rpm.

 

[9secRR]

Way to much overthinking. If you want to build a stroker then build it. If you want stock stroke then build it. It’s all what you want. I like small cubic inch. It’s working for me. Some it might not work.

 

[Bakerlite]

The greater the contact area, the greater the friction.

Sure about that ?
The force due to friction is generally independent of the contact area between the two surfaces. This means that even if you have two heavy objects of the same mass, where one is half as long and twice as high as the other one, they still experience the same frictional force when you drag them over the ground. This makes sense, because if the area of contact doubles, you may think that you should get twice as much friction. But when you double the length of an object, you halve the force on each square centimeter, because less weight is above it to push down. Note that this relationship breaks down when the surface area gets too small, since then the coefficient of friction increases because the object may begin to dig into the surface.

 

[fishmens67]

Since you guys are going over the edge let’s calculate these factors.

what effect does piston coating have. There’s gotta be a reason for it.

let’s calculate the difference between 10-30 oil, 10-40, 20-50, 40 weight, and 50.


How about lead free fuel, racing gas, E85, and alcohol.

spring, summer, and fall racing temps.


How about shift rpm’s. 5700, 6200, 6500, 6700, 7000, and 7500. Feel free to add any other rpm.

I'm working on it, I'll get back to you.

 

[Bakerlite]

Since you guys are going over the edge let’s calculate these factors.

what effect does piston coating have. There’s gotta be a reason for it.

let’s calculate the difference between 10-30 oil, 10-40, 20-50, 40 weight, and 50.


How about lead free fuel, racing gas, E85, and alcohol.

spring, summer, and fall racing temps.


How about shift rpm’s. 5700, 6200, 6500, 6700, 7000, and 7500. Feel free to add any other rpm.

Don't feel intimidated, there's no risk that intellectuals are going to take over this forum..

 

[Bewy]

Bakerlite,
Post #86. I will spell it out for you. Think of a disc brake system. The force of the pad creates friction against the disc. If you use a larger piston, you create more force & the pad pushes harder [ more friction ] against the disc.

In the cyl bore of the engine. Large bore, small stroke. The side thrust on the piston against the bore. If you increase the area of the piston that contacts the bore, it is like using a larger piston in the brake example.

 

[Bakerlite]

You can spell it out for me, but you're talking about increasing the force. I'm not
I'm talking about the same force over a larger area. When you increase the area, for a given weight, you reduce the force per square inch. In fact, if you make the area small enough, one surface will start to dig into the other and increase friction..
Think of walking in the snow, first with regular shoes, then with snow shoes. Or skiing, getting dragged along by your feet, or getting dragged along on ski's.
Obviously the surface has an affect on friction.
That post in 89 I made is quoted from a physics book, so take it or leave it.

 

[Bewy]

Going back to your post 89, maybe you missed the word 'generally'.
Post #92 is about as simple as it gets as an explanation.

 

[pittsburghracer]

Don't feel intimidated, there's no risk that intellectuals are going to take over this forum..

You guys are way to smart for me. I’m like “ Hello, is anybody out there”.

 

[Sublime one]

Change thread title to “Define friction coefficient”

 

[Sublime one]

You guys are way to smart for me. I’m like “ Hello, is anybody out there”.

Side bar,
Yo PR I just picked up a 360 roller cam motor complete with starter, heads, coil, distributor, intake, carb, and valve covers for 200 bucks. It was running when pulled ! Hah! Anyway once winter comes I sure would like to pick your brain on some build guidance. I will keep you posted. Apologies OP did not mean to derail thread. Carry on

 

[Bewy]

Here is a very simple definition of friction, from an Automotive Publication.
Bosch Automotive Handbook, 3rd edition, 852 pages: 'Friction is a physical resistance to relative motion at two or more surfaces in a state of mutual contact'.
DIN 50281 standard.

 

[Bakerlite]

Going back to your post 89, maybe you missed the word 'generally'.
Post #92 is about as simple as it gets as an explanation.

First of all what I'm talking about would fall into the "general" category..
And your "simple" explanation of the brake piston has zero to do with what I'm talking about..
What difference does piston size make if they are both applying the same lbs per square inch.
Fair dinkum, your a knob..

 

[Bewy]

If you cannot understand the simple analogy, it just shows how dumb you are....