goose and slower

[CruiseGTi-R]

Had mongoose fitted yesterday (blueflame system on ebay), great fit. The tip design has changed too, is now 5” rolled in with a kinda internal chamfer.

Couple of things. At first the car was a lot slower, especially pulling at higher speeds in fourth and fifth. Still boosted to 1bar alright, haven’t had to adjust boost or anything.

After a while it got better and better, but it still feels slightly down on power. Any ideas? The previous system on there was almost identical, apart from tanabe back box and oe cat.

Noise wise I can hear the turbo hiss much more, almost to the point where it sounds like a boost leak, but it still hits 1bar ok?

I was hoping it might release a bit of power

 

[rayman75]

mine hisses like fook, i think its more down to the blitz sus filter, and im running 1.2bar now.

 

[CruiseGTi-R]

The filter always hissed/sucked before, but now turbo hiss is def louder.

anyway, its still a bit slower. maybe ecu is in shock.

 

[Gray]

Maybe it takes a while for the exhaust to carbon up and work to its full potential?

 

[CruiseGTi-R]

it did get better during the first hour. at first it was shit slow too.

 

[AJ4]

Its probably because of the 5 inch rolled dustbin welded on the end :lol:

You have a gasket in the wrong place, ie overlapping somewhere and blocking airflow ?

Did you know.... a 5 inch tailpipe robs you of power. An ideal exhaust system would start at 4 inch diameter and narrow down to about 2 inch at the tailpipe. As the gas travels down the exhaust, its cools and slows. The pipe should be progessively narrowed as it goes to keep gas velocity up. When the gas reaches the 5 inch tailpipe it rapidly expands and slows down causing the air to pile up behind it ( like a box does ). By having a 5 inch exhaust you are adding more restriction to the exhaust. Not much effect on a Pulsar admittedly, but always funny when the kiddies fit them to their 1.2 Corsa's for ' mo poowaahhh, innit ' :lol: Almost as funny as fitting rear spoilers on FWD cars

Useless triv for the day...

 

[CruiseGTi-R]

But a narrowing of exhaust dia will increase gas pressure and hence back pressure (although I agree gas velocity will increase).

old system had back box (slows gas flow) and a 5inch tip.

rear spoilers on fwd cars? downforce is downforce?

 

[jpward]

Turbo hiss comes more from the air filter i found and i noticed a slight drop in upper power too with the goose for a while but it is more responsive now.

Whats the fueling like?

 

[AJ4]

rear spoilers on fwd cars? downforce is downforce?

what, pushing the back down and taking the weight off the drive wheels at the front ? :lol:

 

[CruiseGTi-R]

you are joking right?

you're not saying rear spoilers introduce detrimental front lift?

better tell every fwd sports car/race car maker and aerodynamicist on the planet that they've made an awful mistake :-D :lol:

worms exploding out of cans.

 

[Nigell_d6]

what, pushing the back down and taking the weight off the drive wheels at the front ? :lol:

you've been watching top gear:lol:

 

[CruiseGTi-R]

thats explains the mis-information then :roll: :-D

 

[AJ4]

so what happens then genius when you push down on the back of a car then ? The front lifts. If the spoiler is after the rear axle then the axis of rotation around the axle causes the car to lift at the front, unless physics in your universe is somehow different from mine :lol:

Feel free to explain in technical terms why removing weight from the front drive wheels helps traction.

 

[Gray]

I feel this is going to turn into an argument about the theory of relativity. :lol:

 

[AJ4]

nearly... :lol:

The argument is that I believe in physics, which states that a force applied to an object with a fixed centre of rotation will cause that object to rotate around its centre of rotation in the direction of the applied force. Ie, pushing a car down at the back after the axle will make the front lift up

 

[Odin]

Makes sense to me unless you have a nice front spitter fitted which forces the front down as well, So spreading the down force over the whole car . lol.


Rob

 

[macphegf]

Yeah sounds kinda obvious. The racing teams and manufacturers will increase the downforce at the front when they add spoilers to the back I would imagine. Although surely the added downforce at the back is only going to make a real difference at speed when the front wheels tend to have enough grip (for the 1.2-1.4 engines that these guys have anyway ) unless it's wet.

 

[jpward]

I back AJ up as

For every action there is an opposite and equal reaction

example of the point here would be over loading a drawbar what happens????????

Yup the back down=front up steering gets lighter and coefficent of friction deminishes Spoilers on most cars as far as i can see is only for show as most i see arnt true aerofoils! ;-)

 

[geoff pine]

is it fitted with a decat pipe or a muffler type of decat[ silencer box] i have a mongoose and it has a muffler in place of the cat

 

[antgtir]

AJ and Top Gear lol are correct, the added downforce on the rear does have a negative effect on the front grip, however in most cases the effects are not as prominent and the benefits outweigh the negatives of this effect.

As Rob has suggested, manufacturers add small splitters or shapes to the vehicle in order to reintroduce downforce on the front end and to remove understeer problems caused.

As a result of all this downforce is actually a reduction in top speed but very often an increase in traction and manouverability of the car, which in many cases (not 1/4 mile lol) wins as a race is generally won on handling.

If you look at the GTiR the rear wing is more or less directly over the rear axle and so the portion of force acting vertically does so over the rear axle therefore increasing rear traction, the front of the R does have (in all) bad understeer problems but personally i feel that is partly due to the fact that the setup of the car is for "Rally" and so generally the ride height is quite high and so the centre of gravity is high. This is why when people lower (within reason) and stiffen the body i.e. strut braces to prevent body flex, the cars handling is dramatically improved.

For top speed improvement in traction i would recommend a slight tilt forward on the suspension setup in order to compensate for the lift up effect from acceleration, a stiffened suspension setup will help with this as the suspension travel will be reduced.

After all that the conclusion is that the R is a masterpiece (apart from the small mistake of the TMI :lol: )

Ant.