Well I'll be buggered if I can find it
Posted 29 February 2016 - 06:27 PM
I felt that my engine came 'on song' a bit earlier when I fitted a Pipercross substack to mine, 200 or 300 rpm lower, about ~3600.
That would be because of the torque improvements
That's why I fitted it, to improve the torque. I'm only mildly interested in BHPs.
Uncle Cooperman, Voted Mr TMF 2011
Posted 29 February 2016 - 07:41 PM
Maybe on my 'S' the stub stacks replaced some of the lost torque caused by the 1.5:1 rockers 
.
Previously known as 'mra-minis.co.uk'.
Posted 29 February 2016 - 07:53 PM
Peter you should never fit 1.5:1 roller rockers in place of an air filter.... it only filters the really large particles, like your neighbours cat, small children etc...
Moved Into The Garage
Posted 29 February 2016 - 08:07 PM
Oh well, that answers that. Wonder why, as so many of us use HIF44s, stub stacks are so thin on the ground.
It will depend on the air filter you run, however it maybe a waste of time fitting a stub stack to a HIF44, they already have a Bell Mouth machined in to them. The son tried this vs a Stub Stack on the Rollers and there was no measurable difference.
Edited by Moke Spider, 29 February 2016 - 08:07 PM.
Previously known as 'mra-minis.co.uk'.
Posted 29 February 2016 - 08:10 PM
Mr Moke did your son compare the torque curve shape and or position ? what engine spec did your son test ?
Uncle Cooperman, Voted Mr TMF 2011
Posted 29 February 2016 - 08:13 PM
Peter you should never fit 1.5:1 roller rockers in place of an air filter.... it only filters the really large particles, like your neighbours cat, small children etc...
!
Camshaft & Stage Two Head
Posted 29 February 2016 - 08:32 PM
Oh well, that answers that. Wonder why, as so many of us use HIF44s, stub stacks are so thin on the ground.
It will depend on the air filter you run, however it maybe a waste of time fitting a stub stack to a HIF44, they already have a Bell Mouth machined in to them. The son tried this vs a Stub Stack on the Rollers and there was no measurable difference.
I'm using an ITG foam filter. The Bell Mouth you refer to, is it the small radius as shown by my poor attempt at an arrow?
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Well I'll be buggered if I can find it
Posted 29 February 2016 - 09:56 PM
That small radius is a PITA when you're trying to design a nicely-flowing bellmouth. I had to put a little lip on the bottom of my virtual bellmouths to leapfrog the HIF's built in bellmouth. Unfortunately that little lip made them a PITA to print!
Previously known as 'mra-minis.co.uk'.
Posted 29 February 2016 - 10:17 PM
That small radius is a PITA when you're trying to design a nicely-flowing bellmouth. I had to put a little lip on the bottom of my virtual bellmouths to leapfrog the HIF's built in bellmouth. Unfortunately that little lip made them a PITA to print!
Yes that is still a bit sharp for some printers, however a counterbore in to the HIF would sort it out.
Well I'll be buggered if I can find it
Posted 01 March 2016 - 10:09 AM
That small radius is a PITA when you're trying to design a nicely-flowing bellmouth. I had to put a little lip on the bottom of my virtual bellmouths to leapfrog the HIF's built in bellmouth. Unfortunately that little lip made them a PITA to print!
Yes that is still a bit sharp for some printers, however a counterbore in to the HIF would sort it out.
Previously known as 'mra-minis.co.uk'.
Posted 01 March 2016 - 10:12 AM
That small radius is a PITA when you're trying to design a nicely-flowing bellmouth. I had to put a little lip on the bottom of my virtual bellmouths to leapfrog the HIF's built in bellmouth. Unfortunately that little lip made them a PITA to print!
Yes that is still a bit sharp for some printers, however a counterbore in to the HIF would sort it out.
I never thought of that. Is that the way you do it MRA?
I have done, but most customers don't want to spend the extra money to ship their carb body stripped down ready to machine and then pay the extra machining cost, some do but most won't.
Crazy About Mini's
Posted 01 March 2016 - 10:13 AM
My MED stubstack made a decent difference on my 44 with ITG filter..
Up Into Fourth
Posted 01 March 2016 - 10:20 AM
yes when I put in a itg and med substack noticed more mid range torque
over a KN and no substack
Moved Into The Garage
Posted 01 March 2016 - 07:43 PM
Mr Moke did your son compare the torque curve shape and or position ?
Yes
Sparkie
Posted 01 March 2016 - 09:47 PM
I know you can get different results due to cams but a stub stack on my 1330/HIF44 made a difference, I would like to see with a slow motion camera the difference in stand off with and without, sure that would prove the advantage of a stack
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