Exhausting Issues

[Griggsy]

Hi people, I've just joined...great site!! Anyway, I have a question... Has anyone who has done it, noticed any significant power gains when changing from the factory VX V6 2.25" exhaust system to a sports type 2.5", extractors and twin straight thru mufflers. The reason I ask is a mate and I both have VX executive sedans, with the only difference being my mate has just put a new sports exhaust like the one I mentioned above on his while I still have the factory exhaust and in a straight line I can beat him every time over 400m. We are pretty much neck and neck until I reach about 4500rpm and then I start to pull away. Basically, there doesn't seem to be any performance advantage by buying a sports system. Is the factory system already as good as a stock V6 requires? I will say the sports system sounds sweet though!

 

[Phil]

Welcome Griggsy,

It is probable that your mates car is suffering a little from loss of back pressure caused by an improper matching of the exhaust to the engine needs. This can have an overall effect on the cars performance over distance.

If its the noise you want then do a change from the cats back.. Having a 2.5" system is fine just be careful with the types of Hi-flow cat and mufflers, thats were you can come unstuck.

Your mates car is probably quick off the start but no distance speed. (Lots of Top end but low bottom end)

Cheers,

Phil

 

[MaNiac_VP]

Interesting, usually it would be the other way around.
From about 4500 he should start to pull away from you.

Maybe its a **** exhaust, is it straight thru or centre chamber or what??

 

[fergi]

i have a 2 1/2 on my 5 litre v8,it is straight through from the cat back ,it sounds great seems to rev out more freely ,but then that could be imagination,but it definately seems to have more pull mid to high end,did you do a comparison run with your mates car before he put the system on and if so what was the difference then
cheers fergi

 

[Griggsy]

G'day guys,

Thanks for the replies. The two mufflers are inline straight thru's. The only significant difference between our cars is the oil. I use Mobil GF-2 10W-30W(factory standard for the Ecotech), while my mate uses Shell Helix Ultra 15W-50W Semi synthetic friction modified. Can the difference in oil account for his lack of acceleration?

 

[fergi]

dont think the oil would be the difference,how many k,s have each of the motors done and after that i would imagine it would be down to the tuning of the motors,in theory they should be of equal performance,but somtimes you can get a factory motor that has a bit more grunt than normal due to all the bits in the motor matching up better,ie,,the pistons and conrods are all basically the same weight ,the crankshaft suits the pistons and weights therfore you somtimes can get a better balanced motor than normal,this just comes about by luck in the engine factory
cheers fergi

 

[Shiney]

i have just recently got a 2 1/2" plus pacemaker extractors on my vx and i feel a lil in the power gain.

the sound of it is so so so so much better then it was

 

[midnight.outlaw]

What i have heard is that the V6 is not powerful enough to push the air though twin exhuasts without getting too much back pressure. Twin exhuasts are usually reserved for V8's. Better off putting the 2.5 cat back with extractors and maybe even a sports cat, like a 'super cat'. Power gains are resonable.

Jason