I hear all of this talk about all bore motors and bore and stroke motors. Which would be better for a car that is driven 99% of the time on the street?

 

Bore and stroke. You'll make considerably more low-midrange torque with an increased stroke. Torque is a very important requirement for heavy 3500# plus cars with street gears.

 

The only possible advantages to the lg bore only is to unshroud the valves and rev
the begeezes out of it. torque is king on the street. so i agree with denzss

 

Torque is king if you can put it to the ground.


Definatly bore/stroke.

 

Yeah, but you'll hear a lot of silly arguments from people. "I don't want to make torque" "I want low torque so I can launch on the street". Other than those folks, I've never heard anyone tell me or a builder "Now, make sure I don't make too much power."

 

And with an all bore motor you get better piston speed.

 

How do you define better? A bore/stroke motor will generate more piston velocity and piston acceleration than than an "all bore". Changing the bore size has no effect on velocity or acceleration. To change the velocity or acceleration, you must change the stroke, rod length, or both.

 

I think that's his point, understated as it may have been. I ASSumed he meant that by going all bore would result in "better" piston speed, meaning unchanged, in comparison to a stroker motor with higher piston speeds.

 

You're trying to achieve piston speed. There is a limitation to how "much" velocity and acceleration your engine and parts can handle.

GM engines almost always generate more piston velocity than Ford engines. Velocity requires better parts, but makes more power as well.

 

I agree with denz...


Its always a little less stressful on the parts when they dont have to move as far...
all bore is a smarter way to go on a motor for that reason....
however...velocity can be king...If the parts can hold up to it...
just look at some indy cart series cars spinning to 10000+ rpm!!! lots of power....

 

I've got first hand experience with this question, since I've had both types of engine in the same vehicle.

The all-bore MTI 382ci I had put down 455/442 (hp/tq) and was an awesome street engine. The bore/stroked MTI 434ci I had put down 525/519 (hp/tq) but was too much power to easily control. With the 382 I could floor it in 2nd gear and it was very easy to launch on the street. With the 434 I had to half-throttle it until the top of 3rd and when you floored it in 3rd the tires would roast.

Now, for freeway racing, the 434ci just kicked everyones ***. Street racing red light to redlight, the 382ci was a better all-around engine. It was also plenty to handle most cars from a roll.

The 382ci pulled down about 26-27 mpg on the highway, the 434ci averaged 23-24 mpg. Thats awesome considering the power.

I started out with heads/cam in that car but it felt too slow (405/395). I also now have heads/cam in my '02 SS and it feels too slow (427/395). doh!

 

Thanks guys.

 

I agree with Tony. An all bore would be much better. Torque is good but only to a point, I would lose traction from a roll in second with my all bore and it had 478 rwtq and 511 rwhp. The bigger bore will allow to get a better flowing head and make more horsepower. No need for a bigger stroke unless it's a track car in my opinon.

 

I'm in a similar boat, I can't decide between the 382 All bore, 408 Iron Block, and 422 Stroker Motors. I know all of them will make some kick *** power and be fun to race with, but which one for me since I mostly street race and will have a jug attached to whatever it is? lol

 

all bore will make more hp in most cases but I am still scared of the resleeved blocks.