Group 'A' carb? advice needed..

[GTTboost]

Hi guys,

I had my car previously set up to run 18psi by a well known tuner on their rolling road and made 172bhp. I have since fitted an 'uprated' or k-tec fuel pump.. charge cooler..alloy rad.. and seperate mocal oil cooler.. volvo 480 turbo clutch with soft pedal conversion and had an engine rebuild on standard comp. also had a GT tuning adjustable timing sensor, larger turbo downpipe and k-tec zorst.. T25 turbo.

I would like to run more boost, a max of 22psi? I would like some advice as with this T25 is feels sluggish and basically not quick or much fun (it runs very smooth and feels like a new car but slow) I have heard that with a T25 the carb choke sleeve prevents the turbo for being supplied well enough to make it run at its full capicity... and the carb must be modified by removing the choke sleeve and modifying the intake and trans tube?

Then the usual rolling road set up with the larger jets (I am sure my main jet at the moment is 130, not sure about the air corrector...I think its 1.0) but was thinking the main needs to go to 150 and the air corrector .90 and inrich 120?

I will leave this to the guy setting it up on the rollers but I need to know about this carb? (will this be a good choice? K-Tec Racing - Renault Tuning & Styling Specialists ) is this really important and why the performance feels down on power at the mo with my unmodified carb. The boost also drops... it goes to 18psi then immediately drops sto about 15psi and holds at 15/16.

Thanks.

 

[gigaz]

why not fit a wideband lambda? then you would know how rich or lean your engine is running, and jet accordingly.

 

[GTTboost]

why not fit a wideband lambda? then you would know how rich or lean your engine is running, and jet accordingly.

Thanks gigaz, thats good advice with the setting up. I just wanted to know peoples opinions on modifying the carb to gain better performance with a larger turbo at higher boost?

Thanks mate.

 

[F7R-R5]

i think ive got the old carb off my 5 kicking about i will try finding it and let u know wat size jets were in it i used to run 22psi allday every day with it, i removed the choke flap due to never using it or the need for it lol

 

[Bigfoot]

Group 'A' carb? advice needed..

erm, sell it on eBay, they go for nice money and buy a standard one, then get a wideband and sort out standard carb to fuel correctly. Group A carbs are good at overfueling and not good at setting up.

Also all top tuned renault 5s are still running standard carbs fueled correctly.

 

[GTTboost]

i think ive got the old carb off my 5 kicking about i will try finding it and let u know wat size jets were in it i used to run 22psi allday every day with it, i removed the choke flap due to never using it or the need for it lol

Thanks mate, that would be gold dust! Looking forward to knowing what jets you were running.

I have heard a few guys that removed the choke flap. What about on cold mornings when it needs the choke?

Cheers

 

[GTTboost]

Group 'A' carb? advice needed..

erm, sell it on eBay, they go for nice money and buy a standard one, then get a wideband and sort out standard carb to fuel correctly. Group A carbs are good at overfueling and not good at setting up.

Also all top tuned renault 5s are still running standard carbs fueled correctly.

This is what I always thought too... so its not totally required then to run 22psi! Its just if I try and run more than 18 mine pinks.. so I wouldnt run anymore than 18 unless it was fueling spot on. But reading that link to the group a one, it says its a must have for over 20psi.

I would feel much happier having my carb as it is and just the jets set up to run that higher boost!

Thanks for your help guys... really appreciate it

 

[GTTboost]

The other reason I didnt really want a over sized venturi is that when driving around during normal day use... it would be drinking a whole lot of fuel... where as now.. it lasts forever if i'm not boosting it.

So would just changing the jets to larger size mean it would only get the required extra juice when its needed (on high boost) and other times it would give good fuel economy?

I think mine are 130 main, 1.0 air corrector at the mo for 18psi.

 

[GTTboost]

i think ive got the old carb off my 5 kicking about i will try finding it and let u know wat size jets were in it i used to run 22psi allday every day with it, i removed the choke flap due to never using it or the need for it lol

Thanks F7R... any chance of letting me know when u can find out what jets u was using?