crbrlfrost
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| posted on 16/8/04 at 06:51 PM |
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Swindon developed a stressed engine for F3 using the ford SE Zetec block and head, and used a custom valve cover and oil pan to transmit loads between
the tub and transmission. Just a thought, but cleverly designed, they could be used to triangulate the top and bottom of that huge hole we like to
call the engine bay. Cheers!
P.S. Article about the engine appeared in the January 2002 issue of Racecar Engineering.
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locost_bryan
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| posted on 17/8/04 at 03:48 AM |
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quote:
Originally posted by drmike54
Didn't the BAR Honda team blow some engines last year because the engine flexed excessivley under the chassis load and spun the bearings.
... and the McLaren M19 had a similar problem  - cured by putting a stiffer tub on the 19B 
Bryan Miller
Auckland NZ
Bruce McLaren - "Where's my F1 car?"
John Cooper - "In that rack of tubes, son"
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ned
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| posted on 17/8/04 at 08:43 AM |
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I have driven one and been a passenger in another race car, both of which had solidly mounted engines. Both equiped with a vauxhall 16v.
The first, a sports 2000 lola was an ally tub with subframes supporting the engine. There were a lot of vibrations through the ally tub which was very
light, but required soft springing as stiffer springs just meant you'd start flexing the tub.
The second which I should be passenger in again on friday is a space frame sports prototype with the engine gearbox as completely stressed members,
the rear suspension hanging off the gearbox assembly. This also vibrates a lot, things like needles on gauges and mirrors for starters. Obviously this
is a race engine which is rebuilt every year minimum, sometimes more frequently. It is completey balanced (well, probably as far as a 4 cylinder can
be) and the car is thoroughly checked over between qualifying & race sessions, let alone race meetings! Bolts etc always work their way loose over
time. Even trusty nylocks and lock nuts need checking.
I thought about building my car with a solidly mounted engine, but I think the gain will be minimal, if noticable and the vibrations etc not worth the
small gain you might get. It certainly wouldn't be comfortable for longer journeys or our bumpy roads!
You'd be better off sticking to a tried, tested and proven method of stiffening the chassis to get handling gains from the car such also reduce
the unsprung mass and buy some sticky tyres!
as always, just my 2p..
Ned.
beware, I've got yellow skin
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Mark18
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| posted on 17/8/04 at 04:54 PM |
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What about motorbike engines? I was thinking of solid mounting mine into the car simply because that's how it's done on the bike - is this
a wise move?
Mark
"I don't know what I may seem to the world. But as to myself I seem to have been only like a boy playing on the seashore and diverting myself
now and then finding a smoother pebble or a prettier shell than the ordinary, whilst the great ocean of truth lay all undiscovered before me." -
Isaac Newton
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ceebmoj
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| posted on 17/8/04 at 08:01 PM |
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hi,
In 95 (i think) I was lucky enuf to get in a f50 as a pasenger and be driven a couple of laps. wile I will always have rose tinted view of theis
experince (witch was ausem) I have been toled that the vibration that can be felt get anoying on longer genys. to be honest I did not notice and was
probably just shell shocked by the speed and experenced as a whole.
Blake
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Cita
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| posted on 17/8/04 at 08:33 PM |
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I will mount my engine solid into the frame like it used to be in the bike frame.
Being a single cilinder 500 cc i think i'm in for some vibe's!!!!!!!!!!!!!
My car will not be used on the road,just hillclimbing so by the time my teeth are about to shaken out of my mouth the race will be over....i hope
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ZEN
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| posted on 17/8/04 at 11:48 PM |
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Single cilinder locost? Very intersting 
quote:
Originally posted by Cita
I will mount my engine solid into the frame like it used to be in the bike frame.
Being a single cilinder 500 cc i think i'm in for some vibe's!!!!!!!!!!!!!
My car will not be used on the road,just hillclimbing so by the time my teeth are about to shaken out of my mouth the race will be over....i hope
My YouTube channel Cars, bikes - track days, motorsport, sim racing and more.
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silex
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| posted on 18/8/04 at 11:41 AM |
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Remember that the two method of rigidly fixing the engine can have different results an consequenses.
The first is using the engine as part of the structure of the vehicle chassis - thus the term stressed engine/gearbox etc. The engine & gearbox
take direct loads in to their structure. You need to be carefull of doing this with a regular engine as they are not normally designed to handle this
additional loading. The block could twist, etc. causing increased wear and possibly damage to components.
The second is solidly mounting the engine into the frame of the chassis (i.e. just leaving out the iso mounts) in a similar fashion to your average
motorbike. This puts much less stress on the engine as most of it is taken up in the supporting frame around the engine. This as correctly pointed out
can cause high vibration. Just be very carefull of your welding and bracket design when doing this. The vibration caused can produce high fatigue
stresses in the welds and brackets themselves. You may find that you engine mount has suddenly cracked off.
Just a little food for thought.....
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gambrose
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| posted on 19/8/04 at 07:01 PM |
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Aren’t most of the vibration in the vertical plane in line with the cylinders so by clever design you could isolate most of these vibrations with
mountings that took the weight of the engine then with vertical mountings top and bottom you could stress the engine then the chassis twisted which is
what you would want to do to improve torsional stiffness.
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silex
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| posted on 20/8/04 at 07:04 AM |
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Well there are still just as much vibration side to side. Remember the linear motion is being turned into rotary. This is the reason for adding
balance shafts, etc on some of the more expensive engines in order to reduce it and hence create a smoother running lower vibration engine.
Even if you had heavier mounts on the bottom of the engine, you would have to fix them rigid if you wanted to rigig mount on the top of the engine.
Otherwise the natural movement in the lower isomount. would damage the top end which is fixed.
I am not saying dont rigidly fix an engine, but putting forward the fact that there is a little more to than whether it makes your teeth chatter.
My gut feeling would be - if you want to race your machine, rigid mounting is a viable option. If you want to use your car on the road, a lot, then
isomounting is easier on the engine and your backside.
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ettore bugatti
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| posted on 14/10/04 at 06:57 PM |
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sorry for digging up an old thread, but pre war Bugatti's also had solid engine mountings.
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