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Skinners Sprint Micra

Hi guys,

the notion of air rams took my fancy the other day so ive had a look into it, done some sums (internet references might mean im waaayyyyy off the mark here but it was interesting all the same)

Ive taken a standard 4 cylinder engine air consumption & gone against 3k RPM & 6K RPM for my setup breaking down to air consumed per cylinder in litres per second.

Thats 1.3 gearbox, 5.1Final Drive, 195/50/15 Tyres

From this using 3rd gear at 30 & 61 MPH a duct of 57mm diameter (which is the size of the plastic lips around the carbs each cylinder would get roughly double the airflow.

I've yet to work out the pressure difference this would make over the atmospheric the engine would use but it looks worth wile giving it a try :)

 
Quick question peeps, would the best way to measure if any ram affect was taking place be to measure the intake mani pressure?

If the pressure rises with a duct on the there is some sort of affect i guess?
 
frank said:
these are highly recommended paul :) they register half a psi with ease, + pressure or vacuum
http://www.mpdirect.co.uk/p/5909/draper-vacuum-and-fuel-pump-tester
1 or 2 psi is difficult to discern tbh, 3 or 4 psi is bum-dyno noticable :)
Click to expand...

Awesome ta Frank, i imagine il only have very minamal amounts to register but its worth a go for the price of a bit of hose.

Do you think a hose with a lessening diameter say 80/70/60 would help the air gain speed or is that not going to work over only 15 inches of pipe?
 
frank said:
a MAP sensor will meter pressure, a MAF wont tho surely ?
Click to expand...

I guess either would do Frank, im just curious to see if the pressure or flow will see a worth while increase ducted right to the trumpet & by how much :)

Though the Draper gauge would be handy for balancing the carbs too!
 
Skinner_87 said:
Awesome ta Frank, i imagine il only have very minamal amounts to register but its worth a go for the price of a bit of hose.

Do you think a hose with a lessening diameter say 80/70/60 would help the air gain speed or is that not going to work over only 15 inches of pipe?
Click to expand...
i think you would need an intake the size of a windscreen, and a very slow taper to gain 3 or 4 psi @ 100mph personally paul.
a bellmouth and bit of ducting would hardly register on a gauge like mine ^ :)
a ram air setup probably helps intake flow when you hit the throttle and have vacuum conditions in the intake, but once the airflow is up to speed you need proper boost to have any real gains
 
frank said:
i think you would need an intake the size of a windscreen, and a very slow taper to gain 3 or 4 psi @ 100mph personally paul.
a bellmouth and bit of ducting would hardly register on a gauge like mine ^ :)
a ram air setup probably helps intake flow when you hit the throttle and have vacuum conditions in the intake, but once the airflow is up to speed you need proper boost to have any real gains
Click to expand...

Riteo Frank windscreen intake it is :)

I was hoping it might aid the slide opening on the carbs (aided by softer springs) as in 4th & 5th its struggling to get enough vaccum to pull the slides im sure it is.

It should pull over 100 but its really holding back at about 90
 
frank said:
yes mate, 2 screws on the pre-facelift type ones (maybe a separate wire on facelifts ?) the ecu does stuff to the maps over a certain speed if thats still connected eh
Click to expand...

Brill ta Frank, Noddie sent me over the full wiring diagram so il get on that later! Would be a great fix if it works!
 
mine holds back noticeably is its not disconnected paul, and i use my lambda voltage to gauge how much throttle to give on a long hill in 5th gear.
i can slowly increase the throttle and it holds in closed loop, then with a tad more throttle it kicks into open loop/acceleration enrichment.
where,as with it connected it will hold closed loop even if i boot it full throttle (in 4th and 5th)
 
frank said:
mine holds back noticeably is its not disconnected paul, and i use my lambda voltage to gauge how much throttle to give on a long hill in 5th gear.
i can slowly increase the throttle and it holds in closed loop, then with a tad more throttle it kicks into open loop/acceleration enrichment.
where,as with it connected it will hold closed loop even if i boot it full throttle (in 4th and 5th)
Click to expand...
Pin 24 on the facelift cluster, a yellow and blue wire :)

Soon to be unplugged!
 
Front coilovers fitted at last :) bush that was under the top mount was swopped to being over it.

Only problem is the top adjust is touching the bonnet very slightly so the bush will be cut in half and located either side of the top mount for clearance :)

Felt a little strange to drive as the only give seemed to be in the tyres!



 
h701micra said:
Them springs a tad stiff mate?
Click to expand...

These are the 285lb fitted at the minute mate, but yeh when I drove up the edge of the Kirb (only an inch high) it felt like it bounced up and wobbled on the tyres to be honest.

Tyres are set at 30psi on the front but il need to move the bushes about before a proper drive so the bonnet doesn't get damaged
 
Huggy444 said:
Looks a tad low for proper driving too ;) do you get tyre rub now?
Click to expand...
Could be mate, it's basically going to be a circuit setup for what it will get used for :) there's about 10mm of clearance on full lock but it will go higher once I've played about with the mounts a bit! Nothing on this is for form just function :p
 
Skinner_87 said:
These are the 285lb fitted at the minute mate, but yeh when I drove up the edge of the Kirb (only an inch high) it felt like it bounced up and wobbled on the tyres to be honest.

Tyres are set at 30psi on the front but il need to move the bushes about before a proper drive so the bonnet doesn't get damaged
Click to expand...
285 isnt mega either. About 5kg/mm
Are they compression adjustable?
They'll be ok for circuit setup not many curbs on the track ;)
 
h701micra said:
285 isnt mega either. About 5kg/mm
Are they compression adjustable?
They'll be ok for circuit setup not many curbs on the track ;)
Click to expand...

Just adjustable on the rebound bud, good job the hillclimbs on the smoother stuff this year.

It's probably I'm just used to the softer springs to be honest :)
 
Skinner_87 said:
Could be mate, it's basically going to be a circuit setup for what it will get used for :) there's about 10mm of clearance on full lock but it will go higher once I've played about with the mounts a bit! Nothing on this is for form just function :p
Click to expand...

Ahh I guess, keep on forgetting you don't rally...!
Where you just on springs and dampers before then?
 
Skinner_87 said:
Might have to give up on the rallying idea in the next few years, apparently The MSA aren't keen on Type 1 Diabetics holding race/rally licenses without expensive medicals
Click to expand...
Aye I know this. Good friend of mine has the same problem with the msa. Bloody good driver too. I'm no expert on diabetes but I'm sure you'd know if you're ok to race/rally
 
h701micra said:
Aye I know this. Good friend of mine has the same problem with the msa. Bloody good driver too. I'm no expert on diabetes but I'm sure you'd know if you're ok to race/rally
Click to expand...

That's it mate it's easy to manage the longer you have it as I'm finding out. Il just have to try and prove it to the msa!
 

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