AUII XR8 200kw - Torque Increase

[OzriderXR8]

Hi All

I'm sure it's in here somewhere......

What would be a recommendation on increasing torque on the XR8, I'm not fussed about top end or anything else I can't actually use.

Car is not a daily driver but I still want to be able to drive to Adelaide or similar without ruining the national economy.

So far as far as I know everything is pretty stock with an auto, all it has is a Redback cold air intake and a Redback 2.5" Cat Back single exhaust.

I'm not looking at engine surgery, just economic bolt on type stuff.

Any ideas?

[madmelon]

Hurricane 4-2-1 Headers

If you want new cats/don't care about emissions compliance, get some 100CPI metal cats and put them about 300-400mm behind where the collector merges on the headers

A single 2.5" exhaust might be a bit of a restriction. Single 3" probably better and twin 2.5" better again. (I've got the twin 2.5" and it sounds unreal)

[Blue Shadow]

OZ, would you want to go down the chip path? I've been thinking of doing it.

[Bossxr8]

Lower diff gears are the best way.

[Blue Shadow]

What ratio diff in a ute?

[Bossxr8]

Depends if auto or manual i guess. Auto i would say 3.9 or 4.1.

[Blue Shadow]

Thanks Boss, will I only need to buy the guts of the diff or a whole new one i.e axles

[Bossxr8]

Just the ring gear and pinion.

[inventiv]

What about the 70mm throttle body from a 220kw engine?

[OzriderXR8]

All great suggestions but all have a heap of conflicting info re benefits.

I've chipped a couple of bikes and you get the performance but usually at the expense of fuel. No real performance, just different fuel mapping.

If I change the diff ratio I get better acceleration but loose cruising economy.

I guess I'm looking for the old style carb type thing with 2 barrels until you put your foot down and open the secondaries. Vtec style....

[mcfly94]

Get it tuned, youll notice a difference, chuck some 3.9's in its not that bad.

[Strattos]

Originally Posted by OzriderXR8

If I change the diff ratio I get better acceleration but loose cruising economy.

Re the diff gears, I haven't done it myself, but have read other threads where there wasn't necessarily a heap of difference in fuel economy, or not enough that it didn't justify the torque gains in lowering the gearing, depending on how low you go of course.

[LyleXR8]

Diff gears are already good in an AU XR, my manual is well over 2,000rpm at 120, can put a normal falcon diff in to lower revs, dunno how it effects economy or torque though

[T MAN]

diff gears are a good start, gives it a more lively feel, i run 3.91 gear and its no different on fuel as you dont need to load it up as much to get to the speed limit, rpm at 110 isnt to bad at 2500rpm at 110 kmh..

if you want to go for the tunning route can get nice down low torque improvement from a couple of degrees of timing and depending on what or who tunes it, the ecu actually has torque reduction strategies in the ecu that reduce timing under hard load in 1st gear to prevent trans damage, removing these functions make nice improvements...

[Bossxr8]

I got better economy around town with 3.9's, and made hardly any difference on the highway. Not enough to make much of a difference anyway.

[mcfly94]

i will own up to fuel economy going down, 3.9's went and foot went further to the floor, now averages 19.6l/100km around town (stock car mind you)

[Blue Shadow]

Originally Posted by mcfly94

i will own up to fuel economy going down, 3.9's went and foot went further to the floor, now averages 19.6l/100km around town (stock car mind you)

What did you get from a stock diff?

[mcfly94]

Originally Posted by Blue Shadow

What did you get from a stock diff?

Was averaging around 14.7ish

[Blue Shadow]

Big jump

[mcfly94]

Originally Posted by Blue Shadow

Big jump

yeah i do a lot of short drives, and definitely drive it harder since having them in there.

[Blue Shadow]

I do mostly long drives, its not a daily but I go up to Hervey Bay & Bundy most weekends, so it might be worth a crack for me with 3.9 or 4.1. Just gotta find them, how much new would it cost?

[mcfly94]

my gears were about $600 new iirc and then $500 fitted with new bearings

[Blue Shadow]

Thats not to bad if you get some extra torque out of it

[mcfly94]

Originally Posted by Blue Shadow

Thats not to bad if you get some extra torque out of it

definitely, need one of those 'frequently side ways stickers', gears and removing the torque reduction strategies and adding some timing down low made a huge difference!

[Blue Shadow]

Just get it tunes or a J3 chip?

[BOTTLEDUP]

Add cubic inches or a PD blower...

[Sox]

Being auto, the gearing is up the poo.
3.9 or 4.1 gears will help a lot.

The standard headers are garbage, throw on some tri-Y's with 1.5" primaries, Advance or Hurricane.
The single 2.5" system will go ok as you're not chasing top end power.

Then a tune with ignition timing advanced and torque reduction removed and you'll be doing skids all over the joint.

[Blue Shadow]

Originally Posted by Sox

Being auto, the gearing is up the poo.
3.9 or 4.1 gears will help a lot.

The standard headers are garbage, throw on some tri-Y's with 1.5" primaries, Advance or Hurricane.
The single 2.5" system will go ok as you're not chasing top end power.

Then a tune with ignition timing advanced and torque reduction removed and you'll be doing skids all over the joint.

Yeah, I ordered the exhaust, Advance headers, with a single and high flow cats

[OzriderXR8]

What revs are you guys showing at 100kph?

Mine sits on 2000rpm.

[Blue Shadow]

Originally Posted by OzriderXR8

What revs are you guys showing at 100kph?

Mine sits on 2000rpm.

1900 in a ute