TMB
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| posted on 10/6/20 at 06:22 PM |
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Engine mounts to stiffen frame?
Ive got a Dax Rush MC frame. But I'm missing all other parts.
the frame is very light and of the looks of it its not buildt for anything else than a MC engine.
ive got a well buildt C20XE from an other project, QED cams etc. It would be a shame not to use it as it puts out a fresh 200hp.
Anyone tried to mount an engine as a part of the frame? 6-8 engine/gearbox mounts. 80-90 shore 20mm PU brushings with 12.9 8mm bolt through them.
Would it be a good solution to help the frame from twisting?
The XE is a heavy engine (130kg) and the gearbox R28, (35-40kg)
Will the torque make up for the extra kg vs a 65kg Yamaha YZF R1 with 150hp?
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v8kid
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| posted on 10/6/20 at 06:46 PM |
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I put a 5L V8 in a Sylva Riot that was designed for a M/C engine and it was solidly bolted in with 2 points on the engine block, 4 points at the
block/gearbox interface and 2 points at the rear of the gearbox.
It was not particularly easy and I'm not sure I'd do it again. Lengthened the chassis and added extra members to stiffen.
Worked quite well though apart from eating diffs.
Cheers
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
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AdamR20
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| posted on 11/6/20 at 06:11 AM |
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Personally wouldn't have thought poly mounting the engine / gearbox will take much flex out of the chassis, you'd need to hard mount it to
make the engine / box a stressed member.
I've had cars with XE and R1 engines before - with the XE engine at 200bhp I am fairly certainly it will be slower than with the R1 engine at
150bhp.
[Edited on 11/6/20 by AdamR20]
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adithorp
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| posted on 11/6/20 at 08:03 AM |
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quote:
Originally posted by AdamR20
Personally wouldn't have thought poly mounting the engine / gearbox will take much flex out of the chassis, you'd need to hard mount it to
make the engine / box a stressed member.
I've had cars with XE and R1 engines before - with the XE engine at 200bhp I am fairly certainly it will be slower than with the R1 engine at
150bhp.
[Edited on 11/6/20 by AdamR20]
+1 on all that.
Also, hard mounted the vibration would be pretty bad and could lead chassis failure anyway.
Power and torque might compensate for Wright (though I think you'd need approaching 250 from my experience) but what the extra torque
won't do is compensate for the extra weight when cornering or braking.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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v8kid
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| posted on 11/6/20 at 12:17 PM |
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quote:
Originally posted by adithorp
Also, hard mounted the vibration would be pretty bad and could lead chassis failure anyway.
Well, it didn't with me have you had experience of this happening?
Cheers
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
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nick205
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| posted on 11/6/20 at 12:42 PM |
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As mentioned above I'm not sure poly bushing the engine and gearbox to the chassis will stiffen things much. My understanding is you need to
rigidly mount them make the engine and gearbox stressed members to achieve what you're after.
On my Peugeot 205 GTI I've changed the rubber mountings between the monocoque body and the rear suspension subframe to solid Aluminium. You
could tell the difference in the car's handling behaviour straight away. It didn't feel any harsher though, I'd expect to have to
change the torsion springs and dampers to increase harshness (not what I wa after).
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adithorp
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| posted on 11/6/20 at 01:25 PM |
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quote:
Originally posted by v8kid
quote:
Originally posted by adithorp
Also, hard mounted the vibration would be pretty bad and could lead chassis failure anyway.
Well, it didn't with me have you had experience of this happening?
Cheers
I've seen cracks in chassis around the mounting points on a couple of BECs where they've been solid mounted. Solid mounting is s lot more
common in BECs. I guess it also depends on the design of the chassis/mountings, quality of the welding and milage done.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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Sam_68
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| posted on 11/6/20 at 01:46 PM |
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It might be worth observing that the engine can ultimately only transmit as much torque to the chassis as the rear tyres can react to the tarmac.
In other words: the engine has to have something to twist against
The tyres effectively act as a structural 'fuse'.
Although the more torque you have (after it's been multiplied by the gearbox) the more time your chassis is going to spend being stressed close
to that limit.
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ALLAN 14
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| posted on 11/6/20 at 02:21 PM |
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I also have a Dax rush and I am thinking of using the style of mounting as used on the Ford world cop cross member,
My thinking is that if you use the block as an extra cross member as Ford did and also lots of American V8 engines are mounted,
It would give you extra stiffness closer to the front suspensions bottom wishbone connection as the usual angled soft rubber mount will induce
an outward force under braking for example, Quite often when braking hard on the entrance to a corner when you want you steering geometry to be at
its best.
This is just my thoughts on the matter after reading quite a bit on chassis deflection.
Good luck with your build and have you been on the Dax forum yet, Whereabouts are you in the country.
Regards Allan
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britishtrident
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| posted on 11/6/20 at 08:26 PM |
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quote:
Originally posted by ALLAN 14
I also have a Dax rush and I am thinking of using the style of mounting as used on the Ford world cop cross member,
My thinking is that if you use the block as an extra cross member as Ford did and also lots of American V8 engines are mounted,
It would give you extra stiffness closer to the front suspensions bottom wishbone connection as the usual angled soft rubber mount will induce
an outward force under braking for example, Quite often when braking hard on the entrance to a corner when you want you steering geometry to be at
its best.
This is just my thoughts on the matter after reading quite a bit on chassis deflection.
Good luck with your build and have you been on the Dax forum yet, Whereabouts are you in the country.
Regards Allan
The World Cup Crossmember didn't mount the engine solidly it had rubber bushes , it didn't really stiffen the chassis it did two things
it stopped the front x member and steering rack mounting fracturing.
Adding a random stiff member to a chassis dosen't really stiffen a spaceframe chassis with space frames blacksmith type thinking dosen't
work.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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mcerd1
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| posted on 12/6/20 at 10:58 AM |
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quote:
Originally posted by TMB
Ive got a Dax Rush MC frame. But I'm missing all other parts.
the frame is very light and of the looks of it its not buildt for anything else than a MC engine.
and you'd be right - the Rush MC chassis is significantly lighter throughout using thinner tubes 1.6mm rather than 2.0mm on the main chassis
rails (at least on the square tube version, round tubes are even lighter) and smaller diameter round tubes for the triangulation/bracing - which the
designer of the chassis said he was concerned would lead to fatigue failure when converting these to heavier car engines when this was discussed back
in the day 
there were 2 types of 'Rush MC' chassis offered - Square tube or round tube (the round tube typically being with CC&AR suspension) -
not sure which you have ?
but both were much lighter than the car engine chassis versions - being designed to handle much less weight and torque (not going to say less power
cause I've seen some of the turbo busa cars in the flesh  )
They did make a handful of 'special' chassis in heavier round tubes for car engines - but I think there were only 3 made like this
ever.... (one was getting a Audi 20v, one was getting a cossie YB and the other was on the road with an F20c)
Some details on the F20c build here: linky
YB build here: linly
Audi 20v build here: linky
Also I know that the MC CC&AR version has less ground clearance than the std. car engine'd version (not sure about the square tube MC
version) - could even be enough to force the use of a dry sump like in the F20c build...
[Edited on 12/6/2020 by mcerd1]
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Dingz
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| posted on 14/6/20 at 07:31 PM |
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Solid mounting an engine, a certain Mr Chapman did this to try and stiffen his Austin 7 chassis for 750 racing, you couldn't modify the chassis,
but it twisted the block and ran the bearings so I think he built a cage over the engine to give the same effect!
Phoned the local ramblers club today, but the bloke who answered just
went on and on.
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TMB
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| posted on 21/6/20 at 06:20 PM |
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quote:
Originally posted by mcerd1
and you'd be right - the Rush MC chassis is significantly lighter throughout using thinner tubes 1.6mm rather than 2.0mm on the main chassis
rails (at least on the square tube version, round tubes are even lighter) and smaller diameter round tubes for the triangulation/bracing - which the
designer of the chassis said he was concerned would lead to fatigue failure when converting these to heavier car engines when this was discussed back
in the day
there were 2 types of 'Rush MC' chassis offered - Square tube or round tube (the round tube typically being with CC&AR suspension) -
not sure which you have ?
but both were much lighter than the car engine chassis versions - being designed to handle much less weight and torque (not going to say less power
cause I've seen some of the turbo busa cars in the flesh )
[Edited on 12/6/2020 by mcerd1]
Thanks for the information.
I've got the round tube chassis, so I dropped the XE plans and bought a 2006 YZF R1 engine.
And man, its light. I carried into my garage and put it on the floor.
Looking at it I start wondering... If I just had bough a 2009 YZF crossplan engine, or two... And made a new crank ... No... Or just swapped a small
saab turbo on it.. It would have made up for the loss of torque.. 
maybe I will go crazy one day. But first, lets get the project going this winter. (A project thread will come)
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