Jump to content

Performance of twin 2.5” system vs single 4”?


karlp2

Recommended Posts

  • Member
  • Member For: 11y 4m 7d
  • Gender: Male
  • Location: Auckland, New Zealand

Hi, have G6ET with 355rwkw, currently have a full xforce system with the twin 2.5” pipes.  Other mods include a Walbro 400, PW stage 1 intercooler, 1000cc injectors,  GTX3582 gen 2 with flapper mod and porting etc.  Had hoped for more kw from the recent tune, a couple people have suggested that single exhaust 4” system would help, thoughts?  Reluctant to change the exhaust unless it’ll make a difference, wasn’t cheap to buy being a full stainless one.  Thanks

Link to comment
Share on other sites

  • Bronze Donating Members
  • Member For: 8y 4m 9d

instead of me writing a big spill, click here instead. There is some good information and will get you in the right direction. You also have to take other things into account, that affect power, like temps on the day, dyno etc.

 

There are gains to be had by going to a 4" of course and many equations to play with to calculate, as well as pros/cons of going bigger like, it will be louder, likely hang lower etc etc

Edited by MBAF
Link to comment
Share on other sites

  • Puff
  • Gold Donating Members
  • Member For: 9y 10m 25d
  • Gender: Male
  • Location: South Australia

That link reckons a twin 2.5 system only supports 463hp at the crank. On this forum we've seen a twin 2.5 system support more than 670hp at the wheels.

 

Op, post your dyno sheet so we've got more of an idea what's going on.

Link to comment
Share on other sites

  • Bronze Donating Members
  • Member For: 8y 4m 9d

yeah that's not taking into account variables or forced induction. VE on a 2.5" twin setup has flow similar to a single 3.5" (again depending on the setup in question) for all we know currently this could be a sub frame back 2.5" and not full system, plenty of variables here

Link to comment
Share on other sites

  • Puff
  • Gold Donating Members
  • Member For: 9y 10m 25d
  • Gender: Male
  • Location: South Australia
3 minutes ago, MBAF said:

for all we know currently this could be a sub frame back 2.5" and not full system

54 minutes ago, karlp2 said:

currently have a full xforce system with the twin 2.5” pipes

Link to comment
Share on other sites

  • Silver Donating Members
  • Member For: 10y 10m 12d
  • Gender: Male
  • Location: SW Sydney

403rwkw 98 / 438rwkw e85 with twin 2.5" xforce here, same injectors, pump and intercooler. 

Fuel setup (no surge) and gt3540 were the next limitation not exhaust

Unless a sedan version doesn't flow as well as a ute but doubt it

@karlp2 was there some query about your tuner....jet had a few comments iirc lol

4" dump and cat to clarify

Edited by camo86T
  • Like 1
Link to comment
Share on other sites

  • Member
  • Member For: 11y 4m 7d
  • Gender: Male
  • Location: Auckland, New Zealand

Appreciate your feedback.  Yes I’m looking at other tuner options, nothing really jumping out at me with the rep of tuners here

Link to comment
Share on other sites

  • Member
  • Member For: 11y 4m 7d
  • Gender: Male
  • Location: Auckland, New Zealand
2 hours ago, MBAF said:

but "full" doesn't necessarily mean full

By full exhaust I’m talking about from, and including the dump pipe back

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
  • Create New...
'