Mild 383 build

-
273 said:
408 build everyone does anyways.
Click to expand...
The longarm in the 408 will get the boat moving, 3000 stall in a cammed up 383 isn't going to do much for low end torque.
Realistically 3800 stall is the lowest I would go with a 383, but that's me.
Everything I've read so far has me thinking a pig is in the making.
 
fishmens67 said:
The longarm in the 408 will get the boat moving, 3000 stall in a cammed up 383 isn't going to do much for low end torque.
Realistically 3800 stall is the lowest I would go with a 383, but that's me.
Everything I've read so far has me thinking a pig is in the making.
Click to expand...
Torque is created by displacement, which is bore x stroke, yes longer stroke has larger multiplication factor but what is it multiplying, the forces from the piston created by the psi of the combustion, larger piston more force to be multiplied. So bigger bore more force applied to the crank short stroke less multiplying
Smaller bore less force applied to the crank but longer stroke more multiplying kind of equals out at same displacements. (energy cannot be created or destroyed)
 
273 said:
Torque is created by displacement, which is bore x stroke, yes longer stroke has larger multiplication factor but what is it multiplying, the forces from the piston created by the psi of the combustion, larger piston more force to be multiplied. So bigger bore more force applied to the crank short stroke less multiplying
Smaller bore less force applied to the crank but longer stroke more multiplying kind of equals out at same displacements. (energy cannot be created or destroyed)
Click to expand...
so what's your point? do you know what happens to low end torque when a 292 deg duration cam is put in a low compression 383.
 
fishmens67 said:
so what's your point? do you know what happens to low end torque when a 292 deg duration cam is put in a low compression 383.
Click to expand...
Where has it been stated that this is gonna be a low cr engine ?
But to answer the questions depending on cr differences were talking about probably 3-5% less torque which at around 4000 rpms is 1.5-2.5% less hp.
 
273 said:
Where has it been stated that this is gonna be a low cr engine ?
But to answer the questions depending on cr differences were talking about probably 3-5% less torque which at around 4000 rpms is 1.5-2.5% less hp.
Click to expand...
Your book calculations don't work in the real world.
 
73 RR is a heavy car at 3800 lbs, you need all the cubic inches you can get. A mild 500” low deck will pull so much better than a 383, and you can always tell everyone that it’s a 383…
 
fishmens67 said:
Your book calculations don't work in the real world.
Click to expand...
Here's a mild cr 9.2:1 383 where they go from stock to decently hopped up.

At 3000 rpm (buddies stall) goes from stock 383 lbs-ft to fairly health cam 394 lbs-ft.

"We were eager to try one of the new Comp grinds, and ordered up an XE285HL-10. This is a fairly serious hydraulic profile, rated at 285/297 degrees gross duration and spec'ing out at 241/247 degrees duration at .050 inches, with .545/.545-inch lift on a 110-degree lobe separation."

How much less of cr are we talking about 8.2, 8.5 less than 8 ?

https://www.motortrend.com/articles/mopp-0209-upgrading-the-383-magnum-avs-carb/

Torque
RPMSTKHDRSCARBINTKECAM
3000382.7406.3427.1405.5394.2
3200388.1406.6422.6410.9400.0
3400388.3412.6431.9421.2414.7
3600394.6411.2433.7426.1431.5
3800392.4408.3430.8430.0435.5
4000387.2401.3424.6433.0446.5
4200377.8396.2416.4430.1451.5
4400371.4390.2409.7430.1451.8
4600367.8384.6402.0427.8454.2
4800361.6379.5398.5424.3456.6
5000355.1373.4385.6421.3450.3
5200337.2357.8368.1407.7449.1
5400322.8348.5351.4395.1435.8
5600417.0
5800407.6
6000398.2
Horsepower
RPMSTKHDRSCARBINTKECAM
3000218.6232.1244.0231.6225.2
3200236.5247.7257.5250.3243.7
3400251.4267.1279.6272.7268.5
3600270.5281.9297.3292.1295.8
3800283.9295.4311.7311.1315.1
4000294.9305.6323.4329.8340.0
4200302.1316.8333.0343.9361.1
4400311.1326.9343.2360.4378.5
4600322.2336.8352.1374.7397.8
4800330.5346.8364.2387.8417.3
5000338.0355.5367.1401.1428.7
5200333.9354.2364.5403.7444.6
5400331.9358.3361.3406.3448.1
5600444.6
5800450.1
6000454.9
 
Shorty Thompson said:
you do realize that I'm a new at this. I have no dyno numbers.
Click to expand...
That was for fishmens67,

Shorty Thompson, Head wise what do you think you could budget for ? (I'm Canadian so I your guys money goes a lot further than ours so dollar amounts don't mean much for me) any aftermarket heads available in your budget?
 
Oldiron440 said:
73 RR is a heavy car at 3800 lbs, you need all the cubic inches you can get. A mild 500” low deck will pull so much better than a 383, and you can always tell everyone that it’s a 383…
Click to expand...
it's not gonna be a 383 cube. With the pistons I'm using , I'm gonna make those chubby owners scratch their heads. It'll be a 396 Lo-block Mopar.
 
273 said:
That was for fishmens67,

Shorty Thompson, Head wise what do you think you could budget for ? (I'm Canadian so I your guys money goes a lot further than ours so dollar amounts don't mean much for me) any aftermarket heads available in your budget?
Click to expand...
If I can find some, yes. If I have to go looking in Summit,,,,,,, then maybe. Aluminum? Then no.
 
So it sounds like your build is gonna be a stock ish mild hop up.

So basically rebuild what you got, don't worry about the 0.70" over, sounds like you got headers, do you have intake and carb ? If not probably find and air gap or similar, sounds like you got a 3000 stall and 3.73-4.10 gears so you got to pick a cam and cr to work with that. So to me the question should be what cam and cr will work with what you got. So probably something around 224-236 intake duration on a 108-110 lsa with the appropriate cr.
 
If the funds are to limited I'd make sure the bottom is done right (mainly pistons) you can always upgrade top end later in the car.
 
273 said:
So it sounds like your build is gonna be a stock ish mild hop up.

So basically rebuild what you got, don't worry about the 0.70" over, sounds like you got headers, do you have intake and carb ? If not probably find and air gap or similar, sounds like you got a 3000 stall and 3.73-4.10 gears so you got to pick a cam and cr to work with that. So to me the question should be what cam and cr will work with what you got. So probably something around 224-236 intake duration on a 108-110 lsa with the appropriate cr.
Click to expand...
Not,,,,,,,, real certain on the cam just yet. I want something obviously bigger than factory. It'll be matching bumpstick, springs, and lifters though. Firm believer in that.
 
273 said:
If the funds are to limited I'd make sure the bottom is done right (mainly pistons) you can always upgrade top end later in the car.
Click to expand...
Absolutely on that too. Fellow told me they were pretty well balanced factory, but I will look at getting the crank balanced nonetheless.
 
Shorty Thompson said:
Absolutely on that too. Fellow told me they were pretty well balanced factory, but I will look at getting the crank balanced nonetheless.
Click to expand...
By pistons mainly mean they give compression needed, and if you plan it right say you think down road you might get some eg.. tf 240 heads, you could make sure you piston will give the right cr with them too.

Besides that, can the piston handle the power of any possible future upgrades same with rods and bolts etc.. So if there's gonna be zero upgrades in the future than you don't have to worry about that.
 
Shorty Thompson said:
Sorry , didn't see this / forgot to reply. Silvo-lites, 1276, std.
Click to expand...

have you calculated your compression ratio with these slugs? they're listed at 8:1 which by my very scientific WAG probably puts them in the hole a fair bit. that negates a lot of the benefits of your closed chamber head and the quench it (theoretically) brings to the table.

but cut the heads and run a thin headgasket and you can claw back some compression, and you're maybe sitting at 9:1 which, with that 292 cam is gonna be straight dog water.

orrrr... you zero deck the block and use headgaskets to dial in your compression ratio with the piston of your choosing.

orrrr.... you cough up for good high compression pistons from the jump. which, *pulls chance card* advance to 440 source and pay for a stroker instead.

anyway, i think you're shooting yourself in the foot here by using a heavy cast replacement piston in this application. if you were building a tow rig, or something that was in a light car and you wanted a torque monster that was all done by 5K it'd be a different tune i'd be a whistling.
 
273 said:
By pistons mainly mean they give compression needed, and if you plan it right say you think down road you might get some eg.. tf 240 heads, you could make sure you piston will give the right cr with them too.

Besides that, can the piston handle the power of any possible future upgrades same with rods and bolts etc.. So if there's gonna be zero upgrades in the future than you don't have to worry about that.
Click to expand...
Not saying they're won't be. We strive for " bigger is better " theme. As for now I feel like this. If , if! If I were to achieve let's say 425hp from my build with what I'm working with, then I'm happy.
 
junkyardhero said:
have you calculated your compression ratio with these slugs? they're listed at 8:1 which by my very scientific WAG probably puts them in the hole a fair bit. that negates a lot of the benefits of your closed chamber head and the quench it (theoretically) brings to the table.

but cut the heads and run a thin headgasket and you can claw back some compression, and you're maybe sitting at 9:1 which, with that 292 cam is gonna be straight dog water.

orrrr... you zero deck the block and use headgaskets to dial in your compression ratio with the piston of your choosing.

orrrr.... you cough up for good high compression pistons from the jump. which, *pulls chance card* advance to 440 source and pay for a stroker instead.

anyway, i think you're shooting yourself in the foot here by using a heavy cast replacement piston in this application. if you were building a tow rig, or something that was in a light car and you wanted a torque monster that was all done by 5K it'd be a different tune i'd be a whistling.
Click to expand...
Duly noted. I went looking for so aftermarket cast iron heads at Summit. However VEGE heads were the only thing I'd found. And they were out of stock. Plus they wanted a core, so I'm not shipping anything back. So,,,,,, as soon as I get my block back then I'll get my heads done. Btw. My stock piston before boring was .025 in the hole.
 
You must log in or register to reply here.
-

Back
Top