246 replies to this topic

[SukiDawg]

Bell mouthed intake trumpets are available to buy from a variety of sources, but as I have planned on using Jenvey throttle bodies (and thats what is modelled) I will probably use Jenvey trumpets.

As for the layout - there are a number of reasons that I went for that North/South orientation. Its not the layout that is going to be the most efficient in terms of weight (propshaft etc), but pure weight in ltself does not always make the best laptime. It is weight distribution and mangement of weight transfer during cornering and braking that make a car have good handling, and I came to the conclusion that trailing arm rear suspension isn't the best choice for a lightweight vehicle with high power output.

I wanted to use double wishbone suspension for the front and the rear of the car - and I wanted to have a favourable front to rear weight distrubution and good management of weight transfer during acceleration and braking. That line of thinking lead me to engine in the front and rear wheel drive.

My view - all the mini conversions with rear engine rear drive suffer badly from acceleration squat (high rearward weight transfer) due to the rear suspension design. The original concept from Z cars came from autograss racing - where high weight transfer to the driving wheels under acceleration would give better traction on loose surfaces and therefore give you best laptime. If you are planning to race on asphalt, then you do not need the very high weight transfer under acceleration to get the wheels to grip - therefore you are actually giving up cornering ability and ease of handling by using rear trailing arms. Double wishbone seemed best to me for a car designed to run on a conventional circuit, so thats what I've gone for, and that lead into the powertrain layout I'm trying to acheive.

[lager.and.pretzels]

Suki Dawg: What weight distribution did you determine as ideal?

Anyone have any idea what the weight distribution is for Z-Car's based MR minis, or other MR projects?

[SukiDawg]

I don't think there is a magic answer for the "perfect" weight distribution - it is so interlinked with the suspension geometry that the two go hand in hand.

People talk about weight distribution, when actually you are only referring to the "static" weight dist. When the car is accelerating, braking and turning the true dynamic distribution of the weight between the 4 wheels varies, and it is this that you are really trying to influence. you want good weight on the front in braking, and to give a good turn in - but not so much that the back wheels lock.

For a static weight distribution then something close to 50 / 50 seems to be abotut right, as it gives the easiest calculations for the weight transfer and anti-dive / squat features you might engineer into the suspension... But I don't really think there is "perfect" number. It ties in very heavily with the other features of the car.

Along the lines of your other question - if you have full trialing arm rear suspension, it is impossible to put anti squat into the geometry - so to avoid massive rear weight transfer on accel you have to run very stiff at the back. This then compromises the lateral roll stiffness, so these arrangements end up trading off corner exit stability for general grip at the apex. Z cars with the inside front wheel in the air may make for good pictures, but it shows that the setup of the car is compromised.

Just my view though....

[lager.and.pretzels]

I don't think there is a magic answer for the "perfect" weight distribution - it is so interlinked with the suspension geometry that the two go hand in hand.

People talk about weight distribution, when actually you are only referring to the "static" weight dist. When the car is accelerating, braking and turning the true dynamic distribution of the weight between the 4 wheels varies, and it is this that you are really trying to influence. you want good weight on the front in braking, and to give a good turn in - but not so much that the back wheels lock.

For a static weight distribution then something close to 50 / 50 seems to be abotut right, as it gives the easiest calculations for the weight transfer and anti-dive / squat features you might engineer into the suspension... But I don't really think there is "perfect" number. It ties in very heavily with the other features of the car.

Along the lines of your other question - if you have full trialing arm rear suspension, it is impossible to put anti squat into the geometry - so to avoid massive rear weight transfer on accel you have to run very stiff at the back. This then compromises the lateral roll stiffness, so these arrangements end up trading off corner exit stability for general grip at the apex. Z cars with the inside front wheel in the air may make for good pictures, but it shows that the setup of the car is compromised.

Just my view though....

Thats cool. I was just wondering if you had a concept for weight distribution when you started the project. I would like to target 40/60 myself.

Curious: do you know if there are any public cad models of the mini body, or would you be willing to share yours? I could get a nice head start with that shell you made. :)

[thelegg]

any updates ?

[clovus]

I've been watching this come together for a while. Have you seen the aussie legends racing cars? Although you seem quite capable with the design process, They might be able to give you some ideas, or perhaps confirmation of your existing ideas and performance envelope.

www.aussielegends.com.au

Very fast cars but I'm told they a a bit twitchy at the limit by a prominent Motorsport identity here in Australia.

Cheers

Edited by clovus, 21 October 2012 - 09:43 PM.

[Squares]

Great thread suki thanks for sharing.

I look forward to more progress on this fantastic project in the future, I just read the whole lot from the beginning.

[cptkirk]

Any updates??????

[cosi]

Any updates??????

 

^ +1 

[stevenford_uk]

Just read this whole thing and its superb, precisely the way it should be done, UG is a fantastic cad system for this kind of work and you have done it justice bud. Any wait to see it start coming together. I'm taking the opposite approach, cut first whilst thinking and questioning lol.

[Sean12]

Dawg.....over a year since you posted, what's going on buddy, this still happening.

All work and design done so far is top !!!!

[DugganC17]

Read this from the beginning and I must say your cad skills are alot better than mine that's for sure and it's is definately going to be a beast when it's finished

[R1mini]

Read this from the beginning and I must say your cad skills are alot better than mine that's for sure and it's is definately going to be a beast when it's finished

 

I'll put a pound on it, that it will definately never be finished.

 

I don't see the point of spending hours and hours coming up with a 3d cad model of a differential for instance, when you can just plonk it in and see if it fits in minutes. He already has the major components, engine, etc to work with

 

David

[DugganC17]

i was actually on about the car when its finished but haha

 

and do you have a link to where you got your bender from ? and do you think it will bend the seamless tube you have as its meant to be hard to bend

 

cheers Dan

[stevenford_uk]

progress??