Micra Group A Rally Car

Steve green

Steve green

Hi Guys

New to this forum but seen a few of your micra s and thought i would show you our rally car , i share it with a good friend and we both take turns in driving it

Show the changes we have made and problems that we have had

The car is a relatively well known in uk , was originally a Dutch Challenge car
then imported in 2007 i think , used in brc stars of the future by Rob Barrett

Then sold a few times and we bought it in feb 2014

Rough spec

1275 Mildly tuned engine , cams , chip , pistons , janspeed , supposed to be 115bhp with wind behind it
Harry Hockley Dogbox
Gripper diff
Proflex 3 way adjustable
gtir front brakes
Front micra calipers on rear
weld in cage LHD etc etc




















This was as we bought it ,

Then we tried to go through it to sort any issues But we didn't have long till first event
 
Looks very nice :)
I've got a lesser specced 1348cc rally machine, will be out at RAF Fulbeck in a couple of weekends

Let us know how future events go :)
 
so first things we did was give it a proper wash all bolt on panels off and a good pressure wash

Remove the interior and clean and de clutter as it had so many unnecessary parts still fitted

then replace all the standard parts that can put you out of a rally

having been in motorsport for many years i have learnt the hard way

so parts changed

  • oil and filter
  • spark plugs
  • clean air filter
  • throtte cable
  • dizzy cap
  • rotor arm
  • ht leads
  • gearbox oil
  • clutch cable
  • fuel pump
  • fuel filter
  • made new fuel pipes old ones were perished

When i road tested the car the clutch didn't feel very nice so i decided to pull the engine and box out and have a look at what we had bought



we found that the clutch and flywheel was completely knackered

it was a standard machined flywheel which was cracked and excessively worn

so a quick ring to matt humphries who was very helpful and sorted me out with all the bits i needed



so got this very nice billet lightweight flywheel

and i got a ap racing clutch to do the job properly



one thing i noticed was that the new release bearing was shallower than the old bearing which was causing to have to over adjust the cable ,



so i refitted the old bearing and matt got helix to make me a new release bearing to suit but that was a gonna take a few months

next up on the to do list was a bias pedal box as it makes it much better on gravel to drive

i wanted to modify the standard pedal box so i could use the original clutch and throttle pedal





and a large pad to press

on to the shell







and then plumbed it up with some new stainless brake hardlines



that all went fairly well

then i got a bit carried away !



 
Looks like a clean car, what events do you do? As in, what kind area are you based in?

Matt humphries is a top guy, always there to answer a question at any time. He's a micra guru :)
 
Huggy444 said:
Looks like a clean car, what events do you do? As in, what kind area are you based in?

Matt humphries is a top guy, always there to answer a question at any time. He's a micra guru :)
Click to expand...

We have done 4 or so btrda gravel rounds and grisedale stages last year

So i always have a keen interest in making things light as possible and getting the centre of gravity as low and central as possible

i wasn't that happy with running the spare wheel so far back as the rear strut brace of the cage is far to low

so i changed it







also sorted the rear spare wheel well to remove a bit of weight









so back to the cage and weight loss



bit of a blow over with paint and ....



how it looks with the carbon rear cards , carbon spare wheel carrier and a jack bag not looking to bad



so i few other bits i did to lose some weight

a bike carbon silencer that fits mint and was only 17 quid second hand , saved 4.5 kg !!!!!!!



a nice way to get rid of the massive rear bumper mount



and tweek the shape of the bumper





i also noticed that the rear axle was off to one side when we got the car , so i made an adjustable panard rod with rose joints



here it is fitted



cheers
 
Some nice work there.

I think I competed against it's previous owners, and not you.

I would think about fitting rear calipers with cables, a) to get a proper MOT and reduce hassle at scrutineering (they are a MOT and thus a BB requirement) and b) they are needed. As we found out at Abingdon when we lost brakes due to a burst hose, we lost all fluid and then all foot brake action. We only were able to slow the car down due to the cable hand brake. I hate to think what it would have been like without the cables... :eek:
 
SuperUno said:
Some nice work there.

I think I competed against it's previous owners, and not you.

I would think about fitting rear calipers with cables, a) to get a proper MOT and reduce hassle at scrutineering (they are a MOT and thus a BB requirement) and b) they are needed. As we found out at Abingdon when we lost brakes due to a burst hose, we lost all fluid and then all foot brake action. We only were able to slow the car down due to the cable hand brake. I hate to think what it would have been like without the cables... :eek:
Click to expand...

Remember this has a bias pedal box so a front and rear circuit for brakes so if I loose a brake pipe I will still have one circuit working

Also when 2 of my friends own mot stations I don't really need to worry bout cables
 
It will still (or should) fail scrutineering, as all rally cars have to meet C&U regs i.e. have handbrake cables....
 
SuperUno said:
It will still (or should) fail scrutineering, as all rally cars have to meet C&U regs i.e. have handbrake cables....
Click to expand...

Should ! But I done 4 rallies with it and never noticed

I have worked in Motorsport for over ten years running wrc and other cars , won British championship 3 times , over 250 rallies and never had cables fitted once

I get your point but I won't loose any sleep without having them
 
This is fantastic, nice to see more proper competition cars on here. I've got a 1275cc autotest/solo/road rally car that me and my dad are building. Nothing close to this, but it's fantastic to see the quality of work in something like this. The bike silencer is fantastic. Hopefully not too loud!!
 
Steve green said:
Should ! But I done 4 rallies with it and never noticed

I have worked in Motorsport for over ten years running wrc and other cars , won British championship 3 times , over 250 rallies and never had cables fitted once

I get your point but I won't loose any sleep without having them
Click to expand...
I was out on the nicky grist and a lot of stink was kicked up because the car i was supporting did not have them
 
It's interesting. The lad I bought my autotest Micra from just put a Puma autotest car on the road, and only has the hydraulic handbrake. MOT guy was going to fail it for that, but he was persuaded to check with VOSA. And they allowed it because of the fitted ratchet on the HB. Not legit to C&A as far as I'm concerned, and I'm fitting cable HB to mine, but then I question how our Zafira has electric handbrake (no cables other than electric going to rear discs) as standard.
 
Electric handbrakes, just use a motor on a drum to 'pull' on a cable, or a motor in each caliper to a mechanical link. As I understand you have to have a mechnical system as fluid pressure can drop away over time.
 
Over the years I have seen the need for cables on rear brakes discussed many many times when it comes to rally cars. I don't know how the electric handbrake works. but other than that they are needed for an MoT test. It has been widely quoted that quite a few years ago a well know motor manufacturer was told by Essex police that should there be another occasion when one of their rally cars was stopped and it didn't have a working mechanical handbrake the company would be prosecuted. The risk of bad publicity made sure it never happened again.

I have also seen cars being checked at scrutineering for handbrake cables. As scrutineers seem to have their favourite things to check and they don't all check everything, just because it hasn't happened yet doesn't mean it won't. E.G. In South Wales it is common for scrutineers to test the cut off switch works with the engine running. Buthtis didn't happen at the Showground Stages last Saturday.
 
I was pretty pleased with the new engine

Did 7 hrs on rolling road with out any drama s

image.jpg
N
 
I built the engine myself and mapped it on a rolling road in Scotland but took my mate who is a engine engineer for a current wrc team , he did the mapping

152 bhp is pretty good from a micra I would say
 
Steve green said:
I built the engine myself and mapped it on a rolling road in Scotland but took my mate who is a engine engineer for a current wrc team , he did the mapping

152 bhp is pretty good from a micra I would say
Click to expand...

Very healthy number!
And about 125hp at the wheels, you'll be pushing the bigger cars out there :)

Do you mainly rally in Scotland or ever come down South for a few events?
 
Not been on here for along time
thought i would share some of my original engine build pictures and other bits and pieces if your interested

IMG_3781.jpg

bit of R & D

IMG_3787.jpg
IMG_3813.jpg

windage tray
IMG_3817.jpg
IMG_3829.jpg
IMG_3865.jpg
IMG_3875.jpg
IMG_3935.jpg
IMG_3945.jpg

this is the build that made 152 bhp @ the flyweel
had to get a special starter made as i was a bit keen on the compression
 
on a couple rallies when idling for a long time queuing for the start the temperature would rise as the fan and standard rad started to struggle

so i made a new rad

IMG_6455.jpg


then i decided front panels are excess weight so got the grinder out again

IMG_6336.jpg


then just aswell improve the engine mount and lower the engine a bit for c of g

IMG_6530 (1).jpg
IMG_6537 (1).jpg


and tidy the wiring so new wing looms

IMG_6565.jpg

finished

IMG_5268 (1).jpg


and after the hard work ready for a test

IMG_5365.jpg


1st 1400 on btrda , first time a micra has won since 2005 ish , 33rd overall out of 138

IMG_5370 (1).jpg
 
frank said:
in the stock mounts ? iirc one rally member found that the suspension locked up about half way down when he fitted solid arms
Click to expand...

No all good here , although it is on coilovers on the back of that could make a difference

I am currently doing a design for independent rear end but that's along way off

Didn't think rear links were all that trick amongst all the other pictures ?
 
Those flow numbers look like they were done at 20" from the photo (bit blurry). In which case that's suggesting the head capacity is ~139bhp.
 
Low Rider said:
Those flow numbers look like they were done at 20" from the photo (bit blurry). In which case that's suggesting the head capacity is ~139bhp.
Click to expand...

this is the figures for the exhaust port , it made 152 bhp on the dyno ??? and i think there is a little more to come , as the janspeed manifold really isnt very nice
 
Last edited:
Steve green said:
this is the figures for the exhaust port , it made 152 bhp on the dyno ??? and i think there is a little more to come , as the janspeed manifold really isnt very nice
Click to expand...

Would be very interesting to see the sheet for the intake side.
 
Steve green said:
I will see if I can find the book , what equation are using to calculate the theorical bhp , is it determined by revs aswell
Click to expand...

Numbers are based purely on intake head flow capacity, rpm is not a factor.

Horsepower = observed CFM x power coefficient x number of cylinders

Power For Flow at Coefficient----Inches of Water
0.43--------------------------------------10"
0.35--------------------------------------15"
0.27--------------------------------------25"
0.26--------------------------------------28"

If you did the intakes at an oddball number, then you can convert to any one of the above using the below conversions.
12_1.jpg

If for example, you also flowed the intakes at 20" and measured say 140cfm@10mm lift, that would translate to be ~99cfm@10"

Theoretical horsepower = 99 x 0.43 x 4 = ~170bhp
 
Low Rider said:
Numbers are based purely on intake head flow capacity, rpm is not a factor.

Horsepower = observed CFM x power coefficient x number of cylinders

Power For Flow at Coefficient----Inches of Water
0.43--------------------------------------10"
0.35--------------------------------------15"
0.27--------------------------------------25"
0.26--------------------------------------28"

If you did the intakes at an oddball number, then you can convert to any one of the above using the below conversions.
View attachment 60080
If for example, you also flowed the intakes at 20" and measured say 140cfm@10mm lift, that would translate to be ~99cfm@10"

Theoretical horsepower = 99 x 0.43 x 4 = ~170bhp
Click to expand...

I see ?

Have people tried different design exhaust manifolds other than janspeed. ?
 

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