Low Power 172’s

[Bryan]

thought i would post here as no-one else seems to have been bothered by Roamers findings

the standard injectors on the RenaultSport Clio 172 are rated to 42bhp (i think that is right, correct me if im wrong roamer)

with 4 injectors this equates to 168bhp, under a 100% loading, as most know, injectors work better when running at around 80%, which would explain why not many people have hit the magical mark of 172bhp (or 169bhp which it should be)

i think, to vastly improve the performance of the 172 changing the injectors to 55bhp (or around that mark) injectors would be a good place to start, this would make the injectors much more efficient, and possible even improve power

just a little thought of mine

let me know your views below

 

[Tom]

My god, your right.

if ya fit 300bhp injectors would ya get 1200 bhp?

 

[telford_mike]

Sounds logical, wouldnt know where to start to do it.

Warranty

 

[Bryan]

Quote: Originally posted by Tomclio16v on 19 August 2003My god, your right.if ya fit 300bhp injectors would ya get 1200 bhp?


lets not be silly now tom

you know what i mean

 

[Tom]

course i do can you mod injectors?

Youd need a new fuel pump too

 

[Bryan]

no i know, i use netscape and occasionally it does that

edited now

though it doesnt look right anymore

 

[KDF]

Its alright it does that for me in linux too.. its just dodgy code thats all..



As much as I would like to believe it I just cant bring myself to believe that renault would go to all the trouble of tuning this engine and forget to put injectors in that are up to the job..

 

[jabba]

that would be either a scoolboy error or some serious money saving by the fat cats

 

[philip]

the std injectors are 52bhp

 

[Roamer]

ok, just to correct the standard injectors are Peco 042s rated at 52bhp, Ive gone upto the Peco 043s rated at 75bhp, now you cant just swap them cos youll just overfuel as far as Im aware (Not a concern as Im getting a completely new mapped ecu )

 

[BenR]

you will overfuel running off closed loop with higer flow injectors, simple.

But ren didnt go and fit injecotrs that couldnt supply, they are fine for the std application.

 

[KDF]

Okay so the god has spoken.. but..

What your saying is if you wanted to you could fit Peco 043s and get your ecu reprogrammed to alter the fueling so that it was putting out the same amount of fuel ?

Just a theoretical question.. obviously it wouldnt make any difference if it did.

 

[McBunny]

erm why will you over fuel on larger injectors ??? the fuel aint controlled by them is it just injected

isnt it like a straw v a drain pipe

straw can flow 1 litre the drain pipe 5

so you force 1 lite of water down straw it can do it but no more the drain pipe can take the 1 litre and 4 more if need be but it will only do that if you pour more water down it.

isnt the fuel a mesured amount ?? controlled by the ecu ??? so you could fit a drain pipe instead of the standard straws if you wanted



if im wrong im wrong please dont shout

 

[Tom]

thats what i thought

im getting deja vu

 

[Scudetto]

"with 4 injectors this equates to 168bhp, under a 100% loading, as most know, injectors work better when running at around 80%, which would explain why not many people have hit the magical mark of 172bhp (or 169bhp which it should be)"

explain? - if injectors work best when running at 80%, and provide 168bhp at 100%, how does that explain why were not hitting 169bhp?

(Im not a techie, so pls go easy on the answer).

g

 

[Roamer]

The ecu controls the duration of opening on the injector, and therefore in the same duration more fuel is injected.

 

[Tom]

so if you compensated by increasing the air flow = more power with stock ecu?

 

[BenR]

Quote: Originally posted by _KDF on 19 August 2003


Okay so the god has spoken.. but..

What your saying is if you wanted to you could fit Peco 043s and get your ecu reprogrammed to alter the fueling so that it was putting out the same amount of fuel ?

Just a theoretical question.. obviously it wouldnt make any difference if it did.





Yes........

 

[McBunny]

anyway i thought injectors were rated in cc not bhp oh and colour

 

[philip]

Quote: Originally posted by Scudetto on 19 August 2003


"with 4 injectors this equates to 168bhp, under a 100% loading, as most know, injectors work better when running at around 80%, which would explain why not many people have hit the magical mark of 172bhp (or 169bhp which it should be)"

explain? - if injectors work best when running at 80%, and provide 168bhp at 100%, how does that explain why were not hitting 169bhp?

(Im not a techie, so pls go easy on the answer).

g

4x52 = 210

 

[McBunny]

208 lol

 

[BenR]

Quote: Originally posted by dogmaul on 19 August 2003


erm why will you over fuel on larger injectors ??? the fuel aint controlled by them is it just injected

isnt it like a straw v a drain pipe

straw can flow 1 litre the drain pipe 5

so you force 1 lite of water down straw it can do it but no more the drain pipe can take the 1 litre and 4 more if need be but it will only do that if you pour more water down it.

isnt the fuel a mesured amount ?? controlled by the ecu ??? so you could fit a drain pipe instead of the standard straws if you wanted



if im wrong im wrong please dont shout





ARGHHHHHHHHHHHHHHHH

Simply put, no.

The ecu control the amount of fuel injected yes, true. But it uses the injector as the metering device. When open all the time 100% duty it flows the 52bhps worth of fuel (in ltrs/min, gallons/hr or whatever rate you care to use) at a specified pressure, 3 bar in this case.

The injector supplies current to the injector which opens. The ECU controls fuel flow through opening the injector for known periods of time. So the time period the injector is open replates directly to how much fuel is injected.

Its not simply a nozzle, its the valve too......the ECU just opens and closes this valve.

 

[KDF]

208 / 100 * 80 =

166.4 BHP if running at 80% theoretically.

 

[philip]

err make that 4x52 = 208 , he he post digestion maths ...

 

[BenR]

Quote: Originally posted by dogmaul on 19 August 2003


anyway i thought injectors were rated in cc not bhp oh and colour

they are, CC/min @ X Bar/psi

But using BHP is just as easy as its roughly 1/2 pint/bhp/hr

 

[Tom]

and if the other injectors were used at 80%

240bhp? providing you could alter the tb to allow enough air in??

(dont shout again)

 

[BenR]

Quote: Originally posted by _KDF on 19 August 2003


208 / 100 * 80 =

166.4 BHP if running at 80% theoretically.

TADA!!!

and you know what, they come with 166bhp (are meant to). Didnt i say all this about a yr or so ago?

 

[KDF]

So does that mean if you want more power, and you manage to get a bit more air in.. you would deffinatly need a re-map ? or should the ecu up the load on the injectors to cope automagically ?

Because if not you would deffinatly be running lean cause the injectors just wouldnt be supplying the right mix.

 

[BenR]

Quote: Originally posted by Tomclio16v on 19 August 2003

so if you compensated by increasing the air flow = more power with stock ecu?

Ahhhhhh, now toms thinking!

Your just about on the basis of making power, the single thing you concentrate on. Air.........simple.

Fuel holds the energy, simple.......but needs air and heat to burn. So supplying fuel is deal simple, as is igniting it. But air.........supplying air, now thats the complicated part.

The more air you can get in, the more fuel you can burn, the more fuel you burn, the more power you make, simple.

All about processing air.

But on a mass produced engine, you have emissions (most influential factors nowadays) to meet, cost, comfort, size etc etc to think about.

And the secret to all power production, the cylinder head. Same head on a 1.6 block will provide the same power as the same head on a 2ltr block, the 1.6 will just need to run more rpm to process the same amount of air thats all.

Cams, TBs, exhaust systems, are all just efficiency control methods.

 

[KDF]

im confused..

I thought there was only so much air/fuel you could push into a cylinder without going bigger ?

 

[BenR]

Quote: Originally posted by _KDF on 19 August 2003


So does that mean if you want more power, and you manage to get a bit more air in.. you would deffinatly need a re-map ? or should the ecu up the load on the injectors to cope automagically ?

Because if not you would deffinatly be running lean cause the injectors just wouldnt be supplying the right mix.





Yup, aupply more air and dont correct the fueling youll run lean. The ECU does not alter the fueling or compensate at WOT, its not a fully open loop system, its only controlled when running closed.

 

[BenR]

Quote: Originally posted by _KDF on 19 August 2003


im confused..

I thought there was only so much air/fuel you could push into a cylinder without going bigger ?

There is, volumetric efficiency.....max is 100%

SO a 200cc cylinder can only hold 200cc at 100% VE. BUT, itll make twice the power at 10,000rpm than at 5000rpm as long as you can hold the 100% VE which is the hard part and the reason wild cam profiles loose out at low rpm, because they are designed to achieve higest posible VE at high rpm.

But typically the F4R730 at peak power is running about 86% VE IIRC. then it tails off and you might as well shift up.

 

[BenR]

read above. *roll eyes* (jesus jas, we need rolleyes!!!!)

 

[KDF]

Quote: Originally posted by Tomclio16v on 19 August 2003

Quote: Originally posted by _KDF on 19 August 2003


im confused..

I thought there was only so much air/fuel you could push into a cylinder without going bigger ?

why? bikes with half the 172 capacity can produce as much and more bhp then you get torque issues do you not?

sommat about cylinder filling and something else to do with revs

Ye I knew bikes could produce a lot more power than bigger engined cars.. I just didnt put 2 and 2 together to realise it was because bikes could rev 10K+ thereby allowing more air in etc..

 

[Tom]

tis true was a lame post

 

[KDF]

Quote: Originally posted by BenR on 19 August 2003

read above. *roll eyes* (jesus jas, we need rolleyes!!!!)

http://erc.qmuc.ac.uk/rolleyes.gif

here ya go !

 

[BenR]

We need a really really BIG one, that insults like nothing else!

 

[McBunny]

hehe this is what i like a real post thank you roamer and ben i know most of this stuff just needed a few points clearing up hehe ta so so much

 

[Tom]

ok, ok i admit i read ccc once.

this isnt my field

 

[KDF]

Yep its not my field either..(can you tell)



Now when it comes to braking system and whether bigger brakes make any differnce to stopping distances, its a different story