Hi Guys,

I've bought a *MODIFIED* 2003 MCS.

Here's a list of modifications which are linked to the drivetrain only:

-mini madness cold air intake with ciwl mod
-mini madness v2 header
-intake port match and polished
-rmw street cam
-440cc injectors
-jcw GP intercooler
-invidia t1 catback
-15% alta pulley

The question is, I notice my fuel consumption is excessively high comparing with other members from my forum (12 liters per 100km or 19MPG), and also I find my exhaust too loud for a daily driver.

This car came which a reflashing tool similar to what is sold on the RMW website, so I assume it has been tuned by Jan previously.

1. I have the stock headers, will putting it back reduce noise significantly or should exhaust also be replaced

2. Is putting stock injector or JCW, with a retune is advisable with all the amount of mods on my car? I want a compromise betweem fuel comsumption and performance. It is also ok if I don't get the full potential of these mods as long as i'm not damaging the car's components.

Thank you in advance for your input, I will try to come by regularly for any additional info that might be useful.

 

Replace the injectors, the 15% pully, the cam, headers, the catback. You will want to check also to see if they replaced the fuel pumps also because the injectors can only pump as much as the fuel system is sending to them so I would assume it's different than stock, but I could be wrong.

These affect fuel economy the most. The catback is the least of it, but if it's not proper for the vehicle, it's robbing more than it should be.

The intercooler won't rob fuel and can be beneficial even to the daily driver.

The intake port polished ... that you can't do anything about. They either drilled out the intake port or simply polished it ...

The cold air intake can affect fuel economy, but it's probably last on your list. All it does is effectively allow more cool air into the engine vs recycled and warmer engine bay air.

You will also want to ensure the ECU has been returned to stock tune (the flash tool may do this?)

Headers contribute little to the noise factor, most catback systems are what affect the drone or ambient noise.

You can leave your car stock with the bolt ons and not damage the car.

If you're getting that low of consumption, I'd take your car to a tuner or a shop to have them look it over. Something seems more amiss than the components. I would not think you drop 10-15mpg unless you're really hot ******* all the time. Even my Challenger (345 cid) gets better gas mileage and I do hot dog it a lot (track ~8mpg, ave 26mpg, max 32 mpg).

Hope I helped here.

 

A tuned car will get the same MPG and often better than before. I get poor mileage because I have a short commute and the car hardly gets to warm up. Longer trips I get what I should be getting.

Just saying, it may not be the tune.

On the other hand, if it has bigger injectors, and is not tuned properly, it will indeed run rich and get bad MPG. You might want to consider starting with new plugs, and then look into having it tuned. You may be able to use the VIN to double check with RMW about that, and he may be able to help.

The exhaust won't be a huge penalty HP wise, so you can quiet it up, but making sure the car is running correctly and checking that the tune is proper will not effect MPG except for the fact you may just be heavier on the pedal.

 

thank you for your advice so far,

here are also others mods that are on the car if that affects anything:

ferrea valves+1.25mm intake and exhaust 3 degrees
ferrea titanium retainers
detroit tunes bypass valve
jcw spark plugs
msd ignition
nology wires

What are my thoughts so far is replacing the INVIDIA EXHAUST for the sound, and even the MINI MADNESS HEADERS abck to STOCK for both (because emission inspection will be eventually mandatory in my province)...

And do a retune with my that setup. Because I don't want to start looking for stock parts and paying labor to replace them.

Does that sound ok, or to have back to normal fuel consumption, I should remove and go back to stock on the following:

injectors, pulley, head, cat and cam as mentionned. and retune

as for my mpg, my drinving style consistent of few hi rpm shift every now and then, but far for redlining all the time.

thanks

 

Hi,

You do realise you are on the R56 forums but you have a R53??

Also why did you buy a heavily modified car that has been tuned extensively if you are worried about fuel economy?

Do the maths. Even if you improve the fuel economy by 25% (which is extremely unlikely) that is going to save you around $1k per year if you do a large amount of miles per year. It is going to cost you more than that to try and put the car back to a lower tune

Basically it sounds like you bought the wrong car.

 

I'd consider the tune first if you don't mind actually having the mod'd car. I made the assumption you wanted to get rid of them, but if you don't mind, tune it. It'll usually run $200-600 from what I've read other cars expense.

As far as emissions checks, if you pass now, regardless of future changes to the laws, what is currently in effect for that year of car is what you have to follow. Changes to the laws for the following year do not take effect for your car so you don't have to worry as much.

 

Good one robbo. I see this a lot on this forum. You have a sports car, who cares about how much fuel it uses. If you want good consumption, buy a prius. You gotta pay to play.

 

thanks for your responses, sorry didn't realize I posted this thread on the r56 forum, but hey still got good answers anyways.

As for my MPG, I just feel that my MPG is a bit excessive and something might be out of tune, but if you say that this is where my MPG should be at with all these mods, I won't complain and accept the fact.

 

You can remove all your mods and your gas mileage isn't going to change a whole lot. And you'll then have a boring car too boot

I avg ~20-21 in my stock GP. 90% of my driving is short trips (a few miles)...and a heavy foot though.

Like others have said, most actually get better mileage after all their mods.

As far as the exhaust...just get rid of the header. The invidia is a very clean sounding exhaust and not what I'd describe as loud...it is one of the best sounding exhausts....

 

Putting the stock airbox back should quiet things up also. I'm betting you can find someone to swap parts with (probably even kick in some extra money) so it shouldn't cost anything to go back to stock on most components.

 

Bought a pair of roller skates, now I can't jog...