Eurocharged Pulley and Remap didnt quite hit the spot for me.

[V8 Supercharger]

Hello all

First of all, this is in no way a complaint against anyone, this is just my personal opinion and mine alone. Some may agree with what i have to say, though i think most will tend to say the opposite of what im about to say.

As some of you are aware i was at the Eurocharged Day and had some work done on my car, with the anticipation that it will make it faster (as thats what everyone is aiming for)

Anyways, i had the supercharger pulley, Johnsons IC pump, rear cats and middle boxes removed and of course the remap at the end of it.

My car is 2004 S55 and the main thing i was after was to make the car faster on the low end.

Overall the car goes and sounds amazing and im pretty happy with it, and is definitely faster on motorways. However, my only little gripe is that it now seems slightly slower on take off, which defies the whole point.

Im just wondering if anyone else feels the same way with their car, or is it just me?

Im almost certain it may be down to a lack of pressure from the exhaust system, or is that wild thinking. It also seems to be a little hit and miss with which gear it wants to be in at lower speeds. What im after at the low end of things is sharper throttle response.

 

[flango]

Sounds to me as though the exhaust could be the culprit, I went through this get the back pressure wrong and it robs you of torque and bottom end grunt, took me a while to get mine right but now its spot on?

 

[V8 Supercharger]

Did you have the same/similiar mods?

And what did you do in the end, put the middle boxes back in?

On mine, an x-pipe replaced the rear cats.

 

[flango]

Mines only a 230k but it was the exhaust configurations that were wrong on mine, finally took it to someone who knew what they were doing (Tony Banks Automotive Engineering in Leeds) new exhaust running at correct pressure and everything sorted now running A1

 

[SavMan]

It could be back pressure but if you still have stock headers and primary cats its unlikely. Try driving it in manual mode to see if it is gear selection that's the issue, also can you explain a little more about what you are experiencing and under what conditions. For instance is it from a standing start if you punch it or when driving slowly with light throttle before accelerating.

 

[BenzedUP]

I swear those de-cats make the car slower as you loose back pressure..

 

[V8 Supercharger]

It could be back pressure but if you still have stock headers and primary cats its unlikely. Try driving it in manual mode to see if it is gear selection that's the issue, also can you explain a little more about what you are experiencing and under what conditions. For instance is it from a standing start if you punch it or when driving slowly with light throttle before accelerating.

To be honest its both, standing start and low speed rolling, that when you punch it, the car seems to take a little bit of time before really going anywhere. Best way to describe it at the moment would be if you can imagine Turbo lag.

And driving anywhere between 20-40mph its not entirely sure which gear it wants to be in. Mainly im a pretty mundane driver, but at those speeds the cars not too sure wether it wants to be in second, third or fourth gear and will sometimes lurch a gear down. And when you put your foot down it seems to take a second or 2 before dropping down gears.

Like i say, kind of comparable to turbo lag, which is why im thinking pressure at the back, or lack of.

 

[V8 Supercharger]

I swear those de-cats make the car slower as you loose back pressure..

I was led to believe removing the cats would improve acceleration as it lets the charger spool up faster, but there might be a downside to it now aswell.

 

[camerafodder]

I was led to believe removing the cats would improve acceleration as it lets the charger spool up faster, but there might be a downside to it now aswell.

Superchargers are mechanically driven

 

[moonloops]

err.. I always thought that with super/turbo charged cars the perfect back pressure to have was zero as you are "pushing" air/fuel through the engine and that unlike on a NA car there's no need for an exhaust set-up to scavenge..

I'm no expert but could it be the exhaust gas speed that's the problem ?

Also with the change in s/c pulley size is there any sacrifice at the bottom end ??

 

[SavMan]

Try driving it in manual mode to see if it seems faster, you seem to be describing responsiveness rather than actual speed

 

[flango]

err.. I always thought that with super/turbo charged cars the perfect back pressure to have was zero as you are "pushing" air/fuel through the engine and that unlike on a NA car there's no need for an exhaust set-up to scavenge..

I'm no expert but could it be the exhaust gas speed that's the problem ?

Also with the change in s/c pulley size is there any sacrifice at the bottom end ??

Thats true to a point, but when you lift off the exhaust has to have a natural resistance or back pressure, then when you hit the loud pedal you get an instant response, if you have the wrong diameter pipe or mess with cat deletes dpf deletes etc you change this pressure and get exactly what is being described above like turbo lag, it's like driving an old Saab 900 turbo hit the throttle wait then it goes.

A smaller SC pulley gives you gains on the bottom end as it spools up faster mine is noticeably different. Removing cats, X pipes etc will not make the SC spool up any faster all it will do is improve flow through the exhaust if you do this you then have to map the car for the new flow and less back pressure, sometimes this results in a loss of torque so the car feels slower.

 

[SavMan]

The 55K is both forced induction and normally aspirated as the SC has a clutch mechanism.
I can't see it being back pressure the primary cats and headers are pretty restrictive.

 

[flango]

You may well be right most of my experience is on 4 pots and race engines. Where you are screwing every bit of power from them. Never seen this phenomena on a V8 car I must admit but again my experience with V8's is NA big yanks particularly Chevies as used in F1 stock car racing, but even on 4 pots with stock headers and manifolds you get this pressure/flow issue.

 

[camerafodder]

I think its important to remember that forced induction is about getting as much air into a cylinder as possible for a better burn. I assume that there is a reasonable degree of valve overlap on this engine which necessitates the need for back pressure that Ian has already mentioned. Without this back pressure the engine loses precious fresh air charge into the exhaust before the exhaust valves shut which will reduce performance.

 

[joecash]

Welcome to tuning land - always something to do - mine's bog standard - thrills are for the young at heart - me, I'm an old dodderer

 

[V8 Supercharger]

Thats true to a point, but when you lift off the exhaust has to have a natural resistance or back pressure, then when you hit the loud pedal you get an instant response, if you have the wrong diameter pipe or mess with cat deletes dpf deletes etc you change this pressure and get exactly what is being described above like turbo lag, it's like driving an old Saab 900 turbo hit the throttle wait then it goes.

A smaller SC pulley gives you gains on the bottom end as it spools up faster mine is noticeably different. Removing cats, X pipes etc will not make the SC spool up any faster all it will do is improve flow through the exhaust if you do this you then have to map the car for the new flow and less back pressure, sometimes this results in a loss of torque so the car feels slower.

I think this pretty much hits the nail on the head, hit the loud pedal, wait, then it goes.

I did ask a couple of people before i did the mods wether it would improve bottom end performance or not and they all said it would, but to me it seems to have lost something on the bottom end. Perhaps it is a lack of torque.

 

[V8 Supercharger]

Try driving it in manual mode to see if it seems faster, you seem to be describing responsiveness rather than actual speed

It is the actual response im talking about, takes longer than before the mods, which is actually slowing things down rather than helping it go faster.

Will try it in manual mode later and see how that compares . . . . . but i know if your in fourth at about 3,000 rpm and you "accidentally" drop it into second while accelerating, you better be holding on tight.

 

[Cyclone1]

Interesting, mine definitely doesn't do as yours does and we have very similar set ups....see here from a track day post the mods, it is instantly responsive....

http://youtu.be/X4xwGhQHgjs

 

[Cyclone1]

If you haven't already then try the gearbox adaption reset, key in and turn all the way without starting, press accelerator pedal for 5 secs, release and turn key back to off position. Wait 2 minutes then start the engine.

Because of the amount of steady driving I do on the M1 etc, mine soon starts to adapt and my gear changes become a little more sluggish, this method certainly peps it up again..

Jules.