View Full Version : will i run 2 lean?

17-02-06, 01:45 PM
Another tech question poeple.
I have a cat back system and a viper on my cup.
Will it run lean on the rolling road day tomrrow? Im a bit worried!! :(
Thanks iain

17-02-06, 01:47 PM
Going by what I have heard about running a Viper of the R'sport Clio's then I think you may be running lean in the top of the rev range. When I have had cars on the rollers before, I have always got an air/fuel ratio reading, so hopefully Janspeed's rollers will do the same.

17-02-06, 02:12 PM
Yeah, i meant to ask Janspeed that actually, i would like to get an AFR reading too if possible.

17-02-06, 04:21 PM
yeah it'll be lean, but not dangerously

the F4R's like to run a tiny bit lean

17-02-06, 09:44 PM
thanks fred...do you suggest a remap?

18-02-06, 01:18 AM
well let me put it this way

std 172 + viper + catback exhaust = 174bhp

as above + remap = 184bhp

done on Power Engineerings RR

21-02-06, 08:23 PM
Fred...got 144.8 at the wheels on the janspeed rollers (180 bhp @ fly?)
With a viper& catback....i guess it depends on the rollers?

22-02-06, 04:57 PM
sounds fair enough, and yes rollers do vary massivley

pleased with the result?

22-02-06, 08:02 PM
Yer sounded ok to me .... I was expecting about 160 bhp lol
Thanks for the info Fred.

25-02-06, 09:19 AM
filter and exhaust dont really make a huge difference to AFR readings....

if you get manifold matching done then it does run a little lean...14's in part throttle load areas where as for power you want to see 12.9

however many have run this spec with no remap and found it ok....


when they have had a remap they have noticed good gains in power and drivability.