blower torque

[chorty55]

how much torque/hp is needed to turn a serious blower? Has anyone sheared or know of someone who's sheared both a factory woodruff in addition to an added crank pin?

 

[jimjimjimmy]

@Coyote Jack @MiradaMegaCab

 

[chorty55]

i assumed pinning the crank to add strength.

But who's sheared both at once? or has that yet to be accomplished?

 

[Icetech]

i assumed pinning the crank to add strength.

But who's sheared both at once? or has that yet to be accomplished?

doh.. sorry.. i missed the "In addition to".. 6am... more coffee

 

[MiradaMegaCab]

i assumed pinning the crank to add strength.

But who's sheared both at once? or has that yet to be accomplished?

Install an aftermarket SFI approved balancer as the stock balancer will be the weakest link. Then, Pin it!!!

 

[chorty55]

Install an aftermarket SFI approved balancer as the stock balancer will be the weakest link. Then, Pin it!!!

whhaat? all that material going from crank to grade 8 bolts gives out before the key??

 

[MiradaMegaCab]

Yes, the stock harmonic balancer will be the weakest link.
A “Serious” blower will sap up around 250HP in a parasitic loss.

Some great tech in this thread;

CRANK WOBBLE!! Updated, found problem

 

[Icetech]

Yes, the stock harmonic balancer will be the weakest link.
A “Serious” blower will sap up around 250HP in a parasitic loss.

Some great tech in this thread;

CRANK WOBBLE!! Updated, found problem

Crank Wobble was my stripper name...

 

[MiradaMegaCab]

Crank Wobble was my stripper name...

Small shaft size can be an issue, LOL

A “street” blower kit might have a small 7/8” coupler shaft.

Here’s another thread that’ll make for some good reading.

I've lost my boost

 

[chorty55]

Yes, the stock harmonic balancer will be the weakest link.
A “Serious” blower will sap up around 250HP in a parasitic loss.

Some great tech in this thread;

CRANK WOBBLE!! Updated, found problem

that was my goal.

Sounds like they can get hungry and grumpy to build boost off the front of the crankshaft. And i tried finding posts on other sites of a pinned setup failing as well, or if the pin is plenty strong for the torque/stress transferred from the crank snout

 

[Icetech]

Small shaft size can be an issue, LOL

A “street” blower kit might have a small 7/8” coupler shaft.

Here’s another thread that’ll make for some good reading.

I've lost my boost

Mirada, do they take more to run to make higher boost? or is that basically just rpm based no matter what.... not sure how bad backpressure in the intake would effect it. I want to order a dyers kit sooo bad for my 318.. Everytime i see a blower.. i'm like.. DO IT!! although i know how dumb it would be

 

[TT5.9mag]

A top fuel blower takes about 1000hp to turn at 50psi

A roots 6-71 takes about 200hp to turn at 10psi

These numbers are not set in stone as the engine underneath them and the air it consumes, as well as how much power it makes, and boost level are factors.

Richard Holdener has done some testing on it.

 

[TT5.9mag]

although i know how dumb it would be

Dumb? Hell no. Do it! The chicks will be throwing Puxxy at you. It’ll be the greatest thing you’ve ever done. Of course turbos are even better.

 

[Icetech]

Dumb? Hell no. Do it! The chicks will be throwing Puxxy at you. It’ll be the greatest thing you’ve ever done. Of course turbos are even better.

haha i have had turbos.. and a procharger but man.... since i was like 10 i have wanted a big shiny blower... and i already know the woman thing is a lie It would be 60 year old men... and guys with turbos or centrifugals laughing at my 12 seconds blower car

 

[TT5.9mag]

haha i have had turbos.. and a procharger but man.... since i was like 10 i have wanted a big shiny blower... and i already know the woman thing is a lie It would be 60 year old men... and guys with turbos or centrifugals laughing at my 12 seconds blower car

So true. I will say there is no single modification you can make that will have a greater visual impact than a huffer and a couple holleys poking through the hood.

 

[Icetech]

So true. I will say there is no single modification you can make that will have a greater visual impact than a huffer and a couple holleys poking through the hood.

In a few months i will have spare money (house payed off) soo... will see. i figure $7500 all in for a 8-71... i hate switching to an electric fan though BTW.. you will hate it but i almost wanna try 2 street demons.. i really like this carb or just 1 since i only want like 5psi anyway, just enough to be fun

 

[TT5.9mag]

since i only want like 5psi anyway

I like all of it except that ^^^ part. The “I only want XX boost” usually only lasts about 1 day. And I certainly wouldn’t pay more for an 8-71 if I wasn’t trying to make power. Use a 6-71 if you just want a low boost visual set up.

 

[chorty55]

it sounds like if one manages to shear two keys at once, that's a point for a win.

 

[TT5.9mag]

it sounds like if one manages to shear two keys at once, that's a point for a win.

Or a point for poor fitting components.

 

[Icetech]

I like all of it except that ^^^ part. The “I only want XX boost” usually only lasts about 1 day. And I certainly wouldn’t pay more for an 8-71 if I wasn’t trying to make power. Use a 6-71 if you just want a low boost visual set up.

No matter what it's going to be "Low" boost compared to turbo or anything.. reason i was gonna do 8-71 is it's only like $100-200 more than a 6.. and reading what people say is that 8 works less to make boost, has more room for growth in the future..

 

[65TerrorCuda]

4-71 blown for 15 years and no issues. SFI balancer, single key and follow all blower kit instructions, unlikely you'll shatter anything. Cast pistons, 10 psi, zero detonation on 91 pump gas.
Easily keep up with modern muscle or better, maybe not a great street racing setup. Sticks out like a giant shiny aluminum thumb lol.

 

[Icetech]

4-71 blown for 15 years and no issues. SFI balancer, single key and follow all blower kit instructions, unlikely you'll shatter anything. Cast pistons, 10 psi, zero detonation on 91 pump gas.
Easily keep up with modern muscle or better, maybe not a great street racing setup. Sticks out like a giant shiny aluminum thumb lol.

15 years with 10psi? i wouldn't think it would hold up that long.. that's awesome

 

[TT5.9mag]

4-71 blown for 15 years and no issues. SFI balancer, single key and follow all blower kit instructions, unlikely you'll shatter anything. Cast pistons, 10 psi, zero detonation on 91 pump gas.
Easily keep up with modern muscle or better, maybe not a great street racing setup. Sticks out like a giant shiny aluminum thumb lol.

On what?
A 4-71 has very little rotating mass and moves only a fraction of the air that an 8-71 does, requiring much less input torque. While your setup has proven reliable it does not mean the same setup with a much larger blower would be.

 

[chorty55]

Or a point for poor fitting components.

True, but i'm not looking into that variable.

shear is shear. How many foot pounds of torque is needed to shear both a factory key with a 1/4" round pin 180* on the other side, at once?

The hydraulic pump i'm choosing to use will easily gag out a 7 liter cummins. So i think i might be stressing that 3/16" key stock.

 

[TT5.9mag]

True, but i'm not looking into that variable

You should be.