Backyard Racing Boosted Civic

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Originally Posted by Andrew Cooke

it'll be a combination of weight distribution, wheelbase, and maybe C of G. It's possible that bolting a girder under the front bumper would make you faster. I don't think weight per-se would help unless it flattens the tyres out more?

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yes id have to agree with andy, i dont think the weight is helping them, but i bet they have more of it over the front wheels, certainly miller etc have a lot past the front wheels with forward facing turbos, and batterys right behind the front bumper along with tanks for charge coolers and balast. i know some are knocking on the door of 80/20 weight distribuiton. have you corner weighed your car scoff?

i say the weight is not helping becouse the N/A civics are lighter and faster to 60` and not much behind the 330` with no where near the power. the N/A guys average high 1.4x 60`s for the field

wow, 80/20, surely that's not with driver installed? Either way that'll be a huge difference, I'd optimistically put Scoff at 70/30. I'm aiming for 65/35 in my 5 for hillclimbing, I'm at 63/37...

So without reference to all the sums I posted way back...

say Chris is currently 900Kg all up, 70/30 weight distribution, 240cm wheel base, 40cm centre of gravity, and under way can maintain 1G of acceleration before wheelspin.

statically he has 630Kg loading the front wheels
weight transfer at 1G will be 900 * 40/240 = 150Kg
so dynamic load will be 480Kg

So 480Kg vertical load will allow his tyres to pull 900Kg along at 1G, I'll assume that the load-traction effect is linear... (480/900 = 0.533)

so, add 50Kg 60cm forwards of the front wheel line at 20cm height... (I think the quote is "traction by GWR")
That will add 62.5Kg to the front axle and remove 12.5Kg from the rear.
New weight distribution = 72.9%

It's a bit early for this, but CofG will be lower by about 1cm, so now it's 39cm (?)
weight transfer at 1G will be 950*39/240 = 154Kg
giving a dynamic front load of 538.5Kg (at 1G)
(538.5/950 = 0.567)

0.567/0.533 = 1.06, so acceleration should go up to 1.06G, however, weight transfer will go up due to increased traction : 1.06*154 = 163 Kg, so real dynamic load would be 529.5Kg, bla bla bla, call it 1.05G at a guess :D is that enough to make up for the reduced acceleration in the middle section of the track?

bugger, just realised that the 950Kg also needs to be multiplied by acceleration, so that all washes out to ~ 1.045G... not that drivel I wrote before :laugh:

80/20 static would be 720Kg, weight transfer at 1G the same 150Kg, so a dynamic load of 570Kg (570/900 = 0.633, =19% more traction @1G..) bla bla again, 1.14G.

I've just put this lot into a spreadsheet to try to make it easier to change numbers, with my simple linear tyre model the total weight makes no difference to traction, it's all about the distribution, CofG and wheelbase.

eg, extending the wheelbase with a 1m long bar (from rear axel line) would take that 1G up to 1.07G... and 2m up to 1.12G

all according to my dodgy sums...

If your not bothered about handling, im sure massive improvements could be made on the original torsion bar setup, its rediculously heavy, do regulations allow a redesign?

Andy, thankyou, thats fascinating. I'm going to have to read that a few more times to absorb it properly but I get the jist already. Car is 920kg with me in it currently.

You know me, if it doesn't exist in the engine bay I havn't a clue, this is all very new to me so bare with me.

I can see that distribution makes a big difference. I can see that wheelbase makes a big difference too. So a question: will removing most of the travel from the rear suspension affect weight transfer much ? I can imagine that if the rear was 100% solid that during acceleration the rear end won't be able to squat. My mind wants to tell me that this will have the same effect as wheelie bars but I guess I'm missing something obvious ?

I had already planned to work on weight distribution over winter but this is giving me more encouragement to do it.

Tony, I havn't had a torsion bar installed for 5 years :)

stiffening the rear will make no difference to weight transfer.

However, I'm lead to believe that it does improve the 60ft, I can only assume that's to do with stopping the car rocking fore and aft (maybe diagonally?) making the tyres bounce, or maybe it's just a feel thing? Either way, that's a very different effect to fundamentally keeping the weight on the driven tyres.

I think you may find, that if you make the rear end solid, the front wheels may try and leave the ground! But still well worth ago, considering it wouldn't be that hard to knock up..
Wheel bars effectively increase the wheel base? well that's my thinking on it... You'd probably do more good if you made an anti lift kit for the front.. this could, at a guess, be quite easy, you could fit some (harness material, not sure what it is :) ) around the coils of the springs, maybe it would, maybe it wouldn't work.

I'm sure I'll be pointed right :D

And Andy, is there anthing you don't know :D

Yeah, I tried near solid rear suspension last year when I turreted the rear and ran coilovers. It didn't feel that much better in the 60', maybe a bit more controlable if and when spin occured. BUT it felt lethal at the top of the track. It would bounce on the slightest undulation and I had some stomach turning moments after the trap. It got removed and I went back to a normal torsion bar.

The front suspension is pretty good already I think, it doesn't appear to move in the launch. They're very stiff springs which are working much better than the lesser springs I had before. I compromise on the damping though, it seems too stiff is not good, my take on that is the suspension needs to be able to deal with the transients in launch but really I've just set it to whatever works best.

Sorry for making a mess of your thread rob! :crap:

Yeah I could see near solid rear ends being scary at the top end!!

I'm not sure if you've looked into it much, but, I'm sure you can get trick dampers that actually push down when accelerating, design specifically for FWD drag cars.. Not sure if it was BS from the guy I was speaking to though, he was foreign :D

Hahaha don't worry about Rob, he's a ricer these days, and as we own French cars we can ruin his thread, it's in the RTOC rules ;):D:D only kidding rob.

Loving the civic too Rob, looking purposeful these days :agree:

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Originally Posted by Dave Reed

And Andy, is there anthing you don't know :D

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plenty, but I confuse everyone by using O level maths and physics using all the wrong units and terms to solve degree level problems, makes me seem like a flawed genius :laugh:

I'm sure that there is something in damping, but it's the icing on the cake and not the cake itself. Chris will find a lot more performance for a lot less money in the way that he always does.

Yeah wheelie bars effectively lengthen the wheelbase I don't think it's the same as a stiff suspension setup, and they say the longer the arrow the straighter it flies :)

When I looked at buying a civic I started a thead on ht with a fair few people mentioning the longer wheel base eg being the car to go for, did I listen did I f**k. What poundage springs are you fast chaps using? 800lb-1000lb?

Possible Sale of car coming soon!!...

Ok, the time has come to sell our civic project.. Times have changed and other work commitments just mean there is no time or space to carry on with this car... Im going to sell it at a price ive been told by many in the drag racing game is too cheap and id be better of breaking it but i feel its a far price and im looking for Offers over £5,000..... This is the first place ive put the car up for sale...

Does sound like a bargain for all those components and work. Good luck with the sale :agree:

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Originally Posted by Rob@Backyardracing

Ok, the time has come to sell our civic project.. Times have changed and other work commitments just mean there is no time or space to carry on with this car... Im going to sell it at a price ive been told by many in the drag racing game is too cheap and id be better of breaking it but i feel its a far price and im looking for Offers over £5,000..... This is the first place ive put the car up for sale...

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Hectic, good luck with the sale bud worth every penny, bare engine worth more than £5,000 to build.

Well the Civic went to a new home last week.. I think i can say our drag racing days are over and cut short as that cars a 9second car.. I loved every minute of it and met some great people through it and i could say this club got more involved in to the sport.. As times moved on i just dont have the time to race the civic or fund it as now im deeply involved racing 2 porsches in the Porsche Club Champ and a chance to get my hands more involved racing a GT3 carrera cup soon...

Would like to thank Dean and Ant part of BYR racing, awsome mates, and also Scoff plus anyone else involved with us and drag racing over the many years...... :agree::agree::agree:

Dont worry i aint leaving the Club as i still have my PH1 GT :), time to blow the dust of the old girl i feel.....

Thanks all......Project Thread Finished....

:D keep us updated on the porsches too :D

Who brought it Rob?