Regaining lost power down low?

jjj · 27-02-2006, 09:03 PM

Been talking to some exhaust shops in brissy and they reckon if they put a 2.25in pressed bent tail shaft pipe in instead of the 2.5in, it will improve the cars acceleration down low.

They said they often do it on VL 5spd's that are putting out about 105-115RWKW, which currently are running pacies and 2.5in sports system.

Exhaust On my EL is pacemaker 4499's, 2.5in High Flow Cat, 2.5in Redback with 1 muffler.

Anyone done this before? Just want to get that low end power back that i use to have. I am happy with top end at the moment...

Cheers.

ON_DUBS · 27-02-2006, 10:55 PM

are you running all that on a stocko motor? you need the back pressure to warrant all the free flowing stuff. chuck in a performance cam or something beefy dont re-do the exhaust.

eb91xr6 · 27-02-2006, 11:02 PM

i got a 2.5 on mine and it works realy well better then stock coz that was the first thing i did

Grechie · 27-02-2006, 11:39 PM

whats this? a upgraded tailshaft for more low down power?

jjj · 28-02-2006, 01:45 PM

Quote:

Originally Posted by Grechie

whats this? a upgraded tailshaft for more low down power?

you replace the existing 2.5in exhaust tail pipe section that goes from the exit from main muffler and over the diff and out the rear bumper with a pressed bent 2.25in pipe.

anyone ever tried this, cannot put cam in car as engine is under warranty.

ilsautomotive · 28-02-2006, 01:54 PM

I've heard of people going from 2.25 to 2.5, but not the other way. Remember that the engine size is a good 33% bigger than a VL.

I would recommend a diff ratio upgrade instead.

ON_DUBS · 28-02-2006, 03:02 PM

why does everyone always compare stuff with a VL? my g/f has a VL and its a SLUG.

28-02-2006, 03:08 PM

Put a cam in it.

jjj · 28-02-2006, 04:56 PM

Quote:

Originally Posted by Trouty

I've heard of people going from 2.25 to 2.5, but not the other way. Remember that the engine size is a good 33% bigger than a VL.

I would recommend a diff ratio upgrade instead.

Yeah but the vl's that are getting this done are all putting out similar RWKW as my car(probably around 115RWKW). So i don't think engine size has anything to do with it.

Most exhaust shops will recommend a 2.25in sports exhaust on the 119KW 250 EFI crossflow motor(XE-XF falcons). So then why are EA CFI owners getting 2.5in with 120RWKW?

And if i was to put a cam in the engine it would move the power band up even further...........Making it more of a slug off the line.

AshMan · 28-02-2006, 05:44 PM

there was a post on this just yesterday, about having a tuned length and diameter exhaust.

it has nothing to do with the power of the engine, its where you want your power band to be and after the tuned length your exhaust can be 5inchs in diameter and it wont make a difference.

its all in the harmonics.

jjj · 28-02-2006, 06:24 PM

Quote:

Originally Posted by AshMan

there was a post on this just yesterday, about having a tuned length and diameter exhaust.

it has nothing to do with the power of the engine, its where you want your power band to be and after the tuned length your exhaust can be 5inchs in diameter and it wont make a difference.

its all in the harmonics.

DRIFT KING in brissy do this exhaust modification, i think what they do is very well researched and tested...................................

stiddy · 28-02-2006, 06:40 PM

2.25 maybe ok for a VL I6, but they are a little 3L motor..

too small for a 4L falco motor.. leave your exhaust the way it is, its a perfect set up.
ie the paccies, 2.5in pipe, high flow 2.5in cat and the single muffler..

Walkinshaw · 28-02-2006, 06:45 PM

Next person to mention backpressure dies

DUMTEF · 28-02-2006, 07:06 PM

back pressure

: will be lacking with a 3" system

Damo · 28-02-2006, 07:11 PM

isn't 2.25 stock ?

stiddy · 28-02-2006, 07:49 PM

Quote:

Originally Posted by Walkinshaw

Next person to mention backpressure dies

AGREED!! and for those of you that done agree, read this post below

http://fordforums.com.au/showpost.ph...73&postcount=8

Psycho Chicken · 28-02-2006, 08:49 PM

Quote:

Originally Posted by Damo

isn't 2.25 stock ?

LMAO exactly.

2.25 press bent exhaust? Errr he's just selling you the stock one he pulled off half an hour ago to fit a 2.5. Go to someone with a clue.

sphell · 28-02-2006, 09:27 PM

I agree with Jack, a diff ratio upgrade would make a hell of a lot more difference. Changing to a 2.25 would not help performance, and even if it did, the increase would be so small you would not feel a difference anyway!

1TUFFUTE · 28-02-2006, 09:41 PM

Quote:

Originally Posted by DUMTEF

back pressure

: will be lacking with a 3" system

he he

5L · 01-03-2006, 04:25 AM

so to hyjak the thread but i was told by an bloke with a worked holden motor that the way my car does the crackles in the exhaust will stuff my valves up is this true. he said the best way to fix it is to put a resinator on.

Racecraft · 01-03-2006, 05:15 AM

on a mild i6 a mandrel bent 2.25" exhaust and a single free flowing muffler would remove the some of the bottle neck and increase power across the rev range.. The 2.5" is probably abit big on most non cammed 6's but considering ALOT of places don't open the factory cat to 2.5" anyway the cat back 2.5" exhaust is still only as good as the 2.25" cat openings.. I know on my car I lost alot of bottom end when I went to the 2.5" ultra flo cat after the stockie got the death rattles :(

mcflux · 01-03-2006, 01:17 PM

I'm assuming you've got a 3.08 auto.

Stally and/or Diff ratio. That'll fix it. Or a manual conversion (I'll still fly the auto flag though)...

Q=VA doesn't really have much to do with exhaust diameter on its own (although it most likely is the underlying formula), it's a lot more complicated than that and it's something I'm not knowledgable on. But a bigger gauge exhaust generally means it has the capacity to handle a larger flow. The downside to it is, bigger area = slower velocity of flow.

For bottom end power, you want a small gauge exhaust. Problem is it'll bottleneck when you try & rev it.

For top end power, a large exhaust will fix the bottleneck, but will tend to take a bit of oomph out of the lower revs due to Q (flow) =V (velocity) A (area)

Hence why a balance is best, otherwise we'd all have either HG Kingswood peashooters or 200SX Big Berthas hanging under our cars.

The science/art is finding that balance. I should be a demi-god, as I have given an answer yet have not really answered your question at all. Well, a demi-god, or a resident of the Springfield Retirement Village.

Now where's that onion I had for my belt...

INJECTED_250 · 01-03-2006, 08:24 PM

most exhaust guys are just plumbers that got over working with ИИИИ for a living...