Blower Motor..short stroke or longer stroke??

[blackcloud50]

Looking into 351 based centrifugal blower motor for the street and was wondering if it would be better to have a longer stroke (6.2" rod) or shorter stroke 5.4" rod. Would like to shift at 6500 with hydraulic roller.

 

[myshifter]

I like long rod motors, but I would check your rod ratio and piston side load on whatever combo you put together

 

[Grn92LX]

Rod ratio is meaningless. Build the biggest engine you can afford. Bigger the engine, the less rpm's you need to make power.

 

[myshifter]

Rod ratio is meaningless. Build the biggest engine you can afford. Bigger the engine, the less rpm's you need to make power.

man I been doing something wrong for the last 20 years then

 

[Grn92LX]

Times have changed brotha

Go on www.hardcore50.com and ask about rod ratio. You'll get the right answer..8:1 8 rods to 1 crank

 

[myshifter]

when your spinning 9500+ rod ratio means alot. When you build 600+ inch motors alot of things that make no difference on small 6000 rpm street motors mean alot on big inch motors. Rod ratio is far from useless. To each his own

 

[dragnazz5.0]

long rod motors have longer dwell time at tdc than short rod motors do, and they also have lower piston side load. its my understanding that you can take a longer rod and an piston with an offset wrist pin and greatly reduce side load, but im not 100 percent sure on that since its been awhile since ive looked at that stuff. i say build a long rod motor and get it done

edit: to the original poster rod length has nothing to do with stroke. didnt really know what you were asking since you mentioned stroke but than said something about different rod lengths.

 

[blackcloud50]

long rod motors have longer dwell time at tdc than short rod motors do, and they also have lower piston side load. its my understanding that you can take a longer rod and an piston with an offset wrist pin and greatly reduce side load, but im not 100 percent sure on that since its been awhile since ive looked at that stuff. i say build a long rod motor and get it done

edit: to the original poster rod length has nothing to do with stroke. didnt really know what you were asking since you mentioned stroke but than said something about different rod lengths.

I'm sorry I got a little confused. What I meant was would it be better have a 3.85 stroke vs. a 4.00 stroke using a 6.2" rod? Or would it not really matter?

 

[dragnazz5.0]

i dont think it would really matter but you might want to wait and see if rick replies. im not sure if youll have issues with the piston hitting the crank with a 3.85 stroke or not.

 

[vikingpower]

shorter rods can tolerate less octane because of less dwell time at TDC which is good for ****ty pump gas. But longer rods are easier on the pistons. Since you wanna run boost, go with the shorter rods

 

[bluevenom867]

shorter rods can tolerate less octane because of less dwell time at TDC which is good for ****ty pump gas. But longer rods are easier on the pistons. Since you wanna run boost, go with the shorter rods

Shorter rods have been observed to produce slightly more low-mid range torque,and at high rpms can help power because of the shorter dwell time,its not a disadantage.Plus the shorter rods are lighter so thats a plus.

Also,going with a longer rod,you have a short piston to deal with,so its not as stabile in the bore as a shorter rod with tall compression hight piston would be.

Long rod motors IMO are great when you are running alot of boost.

I dont really know if they would be an advantage or not for a nitrous motor...the extra dwell time at BDC might cause the flow to want to back out (revesion) and same with the exhaust,but that could be taken care of by using slight differant vavle opening/closings.

 

[bluevenom867]

Oh,and large stroke motor are king IMO.

Let the torque do the work.

 

[Rick 91GT]

How much boost? Are you willing to buy custom pistons....

The long stroke motors are limited with shelf stock pistons when trying to get to a blower or pump gas friendly comp ratio.

 

[88Stang331]

go with a supercharged 460 BBF and call it good JK i'm with rick on this one, i think the shorter stroke would be better.

 

[blackcloud50]

How much boost? Are you willing to buy custom pistons....

The long stroke motors are limited with shelf stock pistons when trying to get to a blower or pump gas friendly comp ratio.

Boost about 10-12psi and I was going to try to use shelf stock piston.