Kowalski
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| posted on 13/12/05 at 11:08 AM |
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quote:
Originally posted by NS Dev
..........................if somebody can advise me how to run a 5 cyl engine with coil on plug ign on megasquirt then I am open to the idea.......not
sure it's poss tho.
Megaspark ??
Scratch Megaspark, scratch Megajolt too.
[Edited on 13/12/05 by Kowalski]
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Volvorsport
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| posted on 13/12/05 at 11:42 AM |
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ms2 may be able to - its going to be more expensive tho .
with tuning time limited to the track ie you cant just go up up the road for a tune , an MBE or omex ecu etc, will be best , since you have little
setup time ie to pay someone else to do it . Since tuning will be done on a dyno - making it easier will make it cheaper in the long run
www.dbsmotorsport.co.uk
getting dirty under a bus
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NS Dev
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| posted on 13/12/05 at 12:55 PM |
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ok, that's probably the best answer really, as the chap that I would be getting the Omex ecu from does the mapping too, and he is in my
autograss club and is supplying me with a gearbox as well, and has just started installing a rolling road on his own site, as well as the one he uses
at another site, so would be inclined to use him anyway.
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Kowalski
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| posted on 13/12/05 at 01:18 PM |
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MegasquirtnSpark
http://megasquirt.sourceforge.net/extra/setup-wheel.html
Sounds like what you need!
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NS Dev
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| posted on 13/12/05 at 02:35 PM |
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that's what I meant by the generic "megasquirt"
prob is getting it to work with 5 cylinders!
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Liam
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| posted on 13/12/05 at 04:03 PM |
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I believe a number of production cars (fwd mainly though) have a form of passive rear wheel steering to help handling. I'm sure I've been
in one recently and it felt quite strange - must have been a pug 306. Will have to check.
But basically the system works on lateral load rather than roll, so there is no problem with straight line pitch change. The suspension bushes are
designed to compress in such a way under lateral loading that the rear outside wheel toes out subtly. It was definately noticable on the pug (pretty
sure it was a 306 now) but took some getting used to to predict. Certainly increased the neutrality on the FWD car.
I imagine it could be achieved on your car by having all your joints rigid (i.e. rose joints) except your toe link (provided it's at the rear)
which is on rubber or otherwise slightly compressable. Then the outside rear wheel would be forced to toe out slightly under cornering loads.
Obviously the amount of toe allowed and the load required to initiate it needs to be experimented with but should be a simple system and all but
invisible to scrutineers.
Liam
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NS Dev
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| posted on 13/12/05 at 07:11 PM |
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thanks for the ideas, food for thought, thanks Liam, not keen on the rubber but I think there must be another way of doing it.....................if
it is actually worthwhile, keen to find out tho!
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MikeR
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| posted on 13/12/05 at 08:45 PM |
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bitchy comment sent via u2u 
sure there are 5cylinder guys using megasquirt - i'll look them up for you.
(cause if you go megasquirt you can figure out how to do it before i do :p)
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NS Dev
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| posted on 13/12/05 at 09:17 PM |
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LOL
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Volvorsport
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| posted on 14/12/05 at 12:02 AM |
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believe me , MSnS is a PIA , for 5 cyl , you need an audi dizzy , etc etc , trust me , id be doing it already if you could .
the problem is timing intervals , the software wont allow for the timing split on a 5 cyl , now fuelling is a different matter .
www.dbsmotorsport.co.uk
getting dirty under a bus
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NS Dev
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| posted on 14/12/05 at 08:54 AM |
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I do believe you!
That's why I made enquiries with Steve Walford about the Omex unit. I'll be investigating the MBE system as well.
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quattromike
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| posted on 14/12/05 at 04:25 PM |
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I've been thinking about this roll steer as well. getting it to steer in lean but not in bounce.
I did a few sketch es on auto cad but not sure yet how i'm going to post them for you to look at. I've done it before so it can be
done.(the posting that is)
Mike
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NS Dev
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| posted on 14/12/05 at 05:18 PM |
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you can email em to me on n.seviour@ntlworld.com
I have autocad so no probs
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quattromike
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| posted on 14/12/05 at 06:23 PM |
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E-mail sent
now remember it was just a quick drawing so i could see it work in my head better.
Mike
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NS Dev
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| posted on 15/12/05 at 12:50 AM |
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mmmmm interesting!
I'll have another look when I am more awake!!
Certainly has the principles of something that could work, just need to understand the outer ends!
Thanks!
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MikeR
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| posted on 15/12/05 at 12:52 PM |
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had project management moment at work.
We're looking at this the wrong way.
We're not trying to get rear-end steering. We're tying to get your back end to overstear more easily so you've less chance of
understeer when cornering. There are other ways!
Weight transfer for one! Have your entire engine shift 10 mill sideways when you enter a corner
(try explaining that its supposed to do that to a scrutiener!)
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quattromike
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| posted on 15/12/05 at 04:16 PM |
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For everyone else
 
Rescued attachment RWSRUN1j.jpg
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quattromike
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| posted on 15/12/05 at 04:19 PM |
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Just think of the little purple circles at the end of each rod as rod ends
 
Rescued attachment RWSBOUNCE1.JPG
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quattromike
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| posted on 15/12/05 at 04:20 PM |
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also there is no A-arms or trailing arms or such like showinf so you need to use your imagination a bit
 
Rescued attachment RWSROLL1.JPG
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quattromike
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| posted on 15/12/05 at 04:26 PM |
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remember theese are just quick sketches so I could see it work in my head, so it's not a final design in any way
Mike
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quattromike
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| posted on 18/12/05 at 10:07 AM |
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Had a conversation(argument) with someone at work about the rear steer , on a road going car with rear driven wheels I've always been under the
impresion that when cornering right you would want the wheels to steerin to the corner to hold the car in to the apex?
He rekons that it should be the oposite it should steer out to get the back end round.
But if you steer out on a driven wheel does that not give mega oversteer?
I normally listen to what this boy has to say coz he used to build and race sidecars allover the place, but this time i think he could be wrong
I have an old mk2 80 quattro sitting at home and thats where i got the idea of rear steer in my locost and as far as i can tell on the workings on the
rear suspention it steers in on a corner, but if 4 wheel drive still be the same though driving wheel steering in to the corner?
Mike
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MikeR
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| posted on 18/12/05 at 12:04 PM |
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When Nissan did the 300 that had rear wheel steer. I *think* they programmed it so that it steered out of the bend at slow speed to increase the
turning effect of the car and into the bend at high speed to increase stability.
This is a 10 year+ old design but they probably did the maths first.
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Liam
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| posted on 18/12/05 at 03:01 PM |
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I'm afraid the answer is not really that simple, Mike! What way you might want your rear wheels to steer totally depends on the natural
characteristics of the vehicle, the driving conditions, and what you are trying to achieve with your 4 wheel steering. All active systems i'm
aware of (skyline, honda prelude, early 90s F1 very briefly, for example) are capable of turning the rear wheels either way in a corner. The prelude
turned it's rear wheels depending on the angle of the fronts - into a corner at low lock for high speed stability and stable lane changing, but
outwards at high lock for reducing understeer. The F1 system was a complex mapped feedback system that kept the car neutral at all times - mainly
correcting low speed understeer and high speed oversteer. Skyline system is designed for fun - using various inputs to work out the drivers intent,
then usually decides he wants to hang the rear out in a massive power slide, and happily obliges flicking the rear wheels out then in to unstick the
rear, but all the time keeping it under perfect control.
With a simple passive roll or lateral load actuated system you only have the choice to steer the rear wheels one way. NS Dev wants to increase
oversteer and drive even more sideways so his rears want to steer outwards a bit. Production front wheel drive cars only really suffer from
understeer so can also use the rears to shift the balance towards oversteer. Something like a seven is a bit trickier because they can suffer from
either understeer or oversteer. However they tend to be predominantly oversteery, especially at higher speeds and with reasonable power. With a road
going seven you might well want your rear wheels to steer into corners to increase high speed stability and reduce general oversteer - would certainly
help some seven drivers i've seen on tracks! But any low speed understeer (especially in rear heavy becs) will be increased. A track based
seven may want it the other way around to eliminate any understeer, and live with (or try and dial out with spring/damper adjustment) the extra high
speed oversteer.
So hard to find the right answer. Totally depends on your intentions for the car. I would have thought increasing oversteer would be dangerous on a
road going seven - ask all the people who've become intimate with roundabouts/hedges/ditches. I'd really like to see a nice active system
on mine one day, but the complexity would be pretty daunting.
Hope that helps
Liam
[Edited on 18/12/05 by Liam]
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quattromike
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| posted on 18/12/05 at 06:35 PM |
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Yep that sounds about right
Cheers
Mike
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NS Dev
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| posted on 19/12/05 at 09:34 AM |
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quote:
Originally posted by Liam
I'm afraid the answer is not really that simple, Mike! What way you might want your rear wheels to steer totally depends on the natural
characteristics of the vehicle, the driving conditions, and what you are trying to achieve with your 4 wheel steering. All active systems i'm
aware of (skyline, honda prelude, early 90s F1 very briefly, for example) are capable of turning the rear wheels either way in a corner. The prelude
turned it's rear wheels depending on the angle of the fronts - into a corner at low lock for high speed stability and stable lane changing, but
outwards at high lock for reducing understeer. The F1 system was a complex mapped feedback system that kept the car neutral at all times - mainly
correcting low speed understeer and high speed oversteer. Skyline system is designed for fun - using various inputs to work out the drivers intent,
then usually decides he wants to hang the rear out in a massive power slide, and happily obliges flicking the rear wheels out then in to unstick the
rear, but all the time keeping it under perfect control.
With a simple passive roll or lateral load actuated system you only have the choice to steer the rear wheels one way. NS Dev wants to increase
oversteer and drive even more sideways so his rears want to steer outwards a bit. Production front wheel drive cars only really suffer from
understeer so can also use the rears to shift the balance towards oversteer. Something like a seven is a bit trickier because they can suffer from
either understeer or oversteer. However they tend to be predominantly oversteery, especially at higher speeds and with reasonable power. With a road
going seven you might well want your rear wheels to steer into corners to increase high speed stability and reduce general oversteer - would certainly
help some seven drivers i've seen on tracks! But any low speed understeer (especially in rear heavy becs) will be increased. A track based
seven may want it the other way around to eliminate any understeer, and live with (or try and dial out with spring/damper adjustment) the extra high
speed oversteer.
So hard to find the right answer. Totally depends on your intentions for the car. I would have thought increasing oversteer would be dangerous on a
road going seven - ask all the people who've become intimate with roundabouts/hedges/ditches. I'd really like to see a nice active system
on mine one day, but the complexity would be pretty daunting.
Hope that helps
Liam
[Edited on 18/12/05 by Liam]
spot on and exactly right.
I certainly would NOT want to do what I am thinking of for the grasser on a road car, or anything used on tarmac really!
It's very specific to autograss and dirt oval racing really, where the first corner inside line is the place that the race is won or lost. If I
can go in faster and get turned without understeer, and then hold the tight line, I can win. If I push wide, I'll be near the back of the pack
in a second.
The normal way to stop the understeer is a stab on the brake and a bootful of power again, but the amount of brake and power varies dramatically and
it very tricky to judge on a surface that varies in terms of grip from dry tarmac to soap on lino! You only really know how well the car will turn in
when you try it, and by then it's too late!!
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