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Gtir Motorsport club » General Discusion » Gtir related Discussion » Findings regarding air filter types & wheel size used

Findings regarding air filter types & wheel size used

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GTI-R US

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Management
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OK this is not specific to gtir but to many cars and have to say that I'm very surprised by the results.

Basically I carried out a test on our dyno on 2 Renault clio 182s.
Have got 2 cars  one I use on track and another  which is all pretty much stock other than the induction kit fitted which is an apexi cylindrical filter and 17" rims as opposed to the 16" the car normally uses.

The other car which I use on track has the original air box fitted and runs 16" rims but other than that the cars are identical.

So I set about testing them both and as i already knew the track car had more power and Torque over the runs previously done.
I then removed the stock air box from the track car (which has a k&n panel filter) and replaced it with the free breathing apexi filter from the other car and surprisingly it gained around 12 lbft torque and almost 8bhp




However although the non track clio was down on power ..........Test was at 7000rpm (I ran with both cars so conditions were the same) the lower powered car however was actually 8mph faster than the track clio, the only other differing factor was the rim size, track car was running 16s and other car 17s.
So in theory over a set time /  motion such as a 1/4 mile drag race the lower powered car with the bigger rims would actually win!
So next week I'm going to prove my theory and put the 17" rims on the track clio to see what the given speed is on the track car with bigger rims fitted at same rpm, in theory the car should be quicker still.

Assuming im correct then that blows all the myths out the water with regard to car speed acceleration on the smaller rims, as a car would be faster over a set time - motion with larger rims fitted which also means less effort is required from engine and transmission so in theory would be less of a strain on the gtir gearbox 'Pete'  What a Face

The only time the smaller rims would be better would be over short ground coverage, what that equates to in terms of metres i just dont know but it shows that on initial launch the smaller wheeled car would get away quicker but once rolling the larger wheeled car would catch it very quickly given same rpm/gear ratios used on both cars .

Test also proves that a cylinder type induction kit shielded from hot under bonnet temps is much better than an enclosed airbox with panel type filter it also allows engine to breathe better so rpm increases by around 400 at top end of scale as can be seen in the pic.

I'm surprised tbh by both these findings, but live & learn i guess!



Last edited by GTI-R US on 28th July 2016, 11:47 am; edited 2 times in total


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Cosmic73

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Hey Bob, although the rim diameters were different, were the tyre 'rolling diameters' different too?




GTI-R US

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Yes as both rims have 45 profile tyres so an inch overall larger


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Cosmic73

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This makes sense in a way, because the 2 cars have a different overall speed ratios,
The 16 being shorter ratio'd accelerates quicker but power would peak earlier which may explain it's lower top speed?

Mr B

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gtir technician
gtir technician
If those speeds done on rollers it not taking drag into equation, all you doing is changing gearing slightly . may help in some scenarios & not others.
For drag 1/4 mile we tend stick lower sized rims as 50-55 sidewall flex allow more launch contact grip plus lower gearing can be better but once again all depends on vehicle in question as wheel/tyre diameters get played with as cheap way tweak in gear speeds on individual basis .

Air intake is another one where what works well on one doesn't on another, some mafs hate changes as more turbulent air created, some cars already have quite good cold air to standard box while others don't . Major airbox change only real large benefit when asking for massive increase of intake air over standard .

Would love see a good test done on variety of intakes & intercoolers for the R.

GTI-R US

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Management
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yes see your point as you are simply just altering the gearing on both cars by changing the rolling radius but with tyres being final point of contact on any car im just saying that over a measured time and distance at a set maximum rpm the car with the bigger wheels would get to that set distance faster than car with smaller wheels, which i could actually prove on our dyno 1/4 mile run.
Would also be less effort required from engine & transmission.
The drag factor is irrelevant on the test as its done in controlled conditions with both cars being identical

With intercoolers, intakes on gtir i have actually carried out some tests (not so much with intake charge temps) but with terms of lag encountered on large ic and pipework and its a bit misleading as a car with more lag will feel faster due to power rushing in all at once where as a short direct pipe run with small ic will bring on boost much more linear (making car feel slower and not as powerfull)
But once again if you go by ground coverage of both cars the more responsive turbo'd car will get to its finish point faster than the laggier car with both cars having the same power level.
There are however lots of variables to be taken into consideration but but both tests done on same day and same conditions.
Not tested filters yet but one day il get round to doing a test but think on any of the common makes such as  Blitz, Apexi, k&n, Hks, pipercross etc will give pretty much the same results assuming all are clean but then i could be wrong lol


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johnny gtir

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But like anything B so many factors to take into account do 5 runs in the same car from the same  or as close as possible  conditions and all 5 would give different data readings

People talk about Intercooler lag etc but don't realise the noticeable difference they would gain so many other things sometimes cheaper things would far benefit there car

GTI-R US

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Management
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yes thats right Johnny thats why we always do 3 runs minimum sometimes 5 then take the middling reading as the best to determine the vehicle power, unless of course you are just wanting pub bragging rights where you would take the highest figure lol
Its the whp that is best used to determine gains & losses as that at end of the day is what your putting down on the tarmac but people like to use power @ fly as its a bigger figure and makes people think they have something faster than what it actually is.
This is reason why a lot of newer cars being 2wd and around 250hp atw could thump a pulsar around a curcuit on a dry day as less losses atw and overall most are considerably lighter so power to weight ratio is much better.
Some gtir's weve run can and have had in excess of 25% losses at wheels over fly so in reality a 360bhp pulsar could only be running 260-270atw, now compare that to a 200bhp N/A car such as a later clio or honda civic type r and youve really got a battle on your hands to shake the thing off your tail


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Mr B

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gtir technician
gtir technician
^ RR is totally different as no air drag. larger rolling diameter increases gearing which makes car work harder at times, If you imagine your theory with really large increase in rolling diameter you can easily see potential downfall . increase gearing to much and time of acceleration will drastically reduce .

Mr B

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gtir technician
gtir technician
I quite agree johnny, it massive task make testing accurate, just interested in results of common filter kits & common coolers such as china ones, forge, radtec & standard & arc on a R at around 350hp with pressure loss & temps pre/post coolers .

toaster55

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I had a 182 sport, fooking loved it, as revvy as a type R and a shift light as standard,lol. Misses thought it was fast and never took it over 5 grand

GTi ARGHH


@GTI-R US wrote:yes thats right Johnny thats why we always do 3 runs minimum sometimes 5 then take the middling reading as the best to determine the vehicle power, unless of course you are just wanting pub bragging rights where you would take the highest figure lol
Its the whp that is best used to determine gains & losses as that at end of the day is what your putting down on the tarmac but people like to use power @ fly as its a bigger figure and makes people think they have something faster than what it actually is.
This is reason why a lot of newer cars being 2wd and around 250hp atw could thump a pulsar around a curcuit on a dry day as less losses atw and overall most are considerably lighter so power to weight ratio is much better.
Some gtir's weve run can and have had in excess of 25% losses at wheels over fly so in reality a 360bhp pulsar could only be running 260-270atw, now compare that to a 200bhp N/A car such as a later clio or honda civic type r and youve really got a battle on your hands to shake the thing off your tail



Personally I think the reason is not just because they are 2wd but the fact newer stuff is much more advanced. The power picks up so early and smoothly so you dont have to rev the tits off things anymore to actually get any where. Thats how they get all green about it and mpg's etc. The 300bhp rally cars might "only" have 300 but its all the torque thats made so low down. 300bhp but kind of untouchable without it just being down to gearing.

Most of the expensive stuff are autos, I expect to stop expensive gear boxes blowing up and to stop engines getting ragged well past their comfort zones and warranties looking bad for dealer ships etc.

Much more fun giving it the big revs and glad the R hasnt got 10 computers on the gearbox, 5 computers on the steering wheel computers up its arse etc. Thats what keeps them raw!!


My other halfs diesel fiesta is free road tax and low on power but the way it picks up is always a nice surprise. Its not fast but you can change up so early and at low revs it feels kind of on tap. Would love to get a 3071 on that, then would be a right laugh to see her reaction on a quick blast!

boyciegtir325


Good interesting read Bob - Hope to pop down soon !

GTI-R US

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Management
Management
Well i have to admitt im wrong with this after taking the car on track yesterday and using 17" rims as opposed to the 15s i previously ran. The car was definately slower with the larger wheels fitted infact it made the car very unresponsive so wont be trying that again Laughing

Even did an equasion to work out (based on wheel size 17 v 15) how far ahead on a 1/4 mile run the larger wheeled car would finish and the distance os surprising

Lets see who can work that out Question

But obviously the other factors do outweigh the extra gained in revolutions of the larger diameter wheel


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nomad

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How do you even begin to work that out lol ....


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johnny gtir

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There is working out for everything it's not timed but you could add that no aswell distance by rim/tyre size then add the time factors in. I know there are apps to work out your quarter mile times of your car not sure how much real life situation they add ie weather driver etc

johnny gtir

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As for working it out I ain't even thinking about it or it will do my head in at graft all day

GTI-R US

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@nomad wrote:How do you even begin to work that out lol ....


il give you's a clue pie


Very Happy


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nomad

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Do you have to bring up pie im on a diet lol


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Did someone mention pie drool

GTI-R US

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Greeeeedy bastads Laughing

Come on must be one of you clever chappies on here that can work it out, im surprised no one has done so yet scratch
will let you have day or so to see if anyone can work it out and then il tell you, think youll be surprised by the answer


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DC313

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34.5m assuming a 225 tyre width?

Stu

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@GTI-R US wrote:Well i have to admitt im wrong with this after taking the car on track yesterday and using 17" rims as opposed to the 15s i previously ran. The car was definately slower with the larger wheels fitted infact it made the car very unresponsive so wont be trying that again  Laughing

Even did an equasion to work out (based on wheel size 17 v 15) how far ahead on a 1/4 mile run the larger wheeled car would finish and the distance os surprising

Lets see who can work that out Question

But obviously the other factors do outweigh the extra gained in revolutions of the larger diameter wheel

17" wheel does 931.76 turns to complete 1/4 mile
15" wheel does 1056 turns to complete 1/4 mile

Thats as far as I care to work it out lol


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gtir_woody

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^ surprised by the difference Stu, never thought about it like that before.

shroom

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@gtir_woody wrote:^ surprised by the difference Stu, never thought about it like that before.

Its because Stu needs to know how many turns of the wheels it takes to push his R back home as its always broken down...

I blame the owner lol

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