AUII XR8 200kw - Torque Increase

[T MAN]

3.9 gears put mine at 2500rpm @ 110 kmh

[OzriderXR8]

I'll take it a run shortly and see what it does at various speeds, gps and speedo.

[castellan]

One thing you must do if you have messed with the exhaust is to get it tuned for it, as you will only loose power by exhaust alone and that's a fact !

If you want more torque change the cam, as that's the heart of the engine that rules such things.

[Blue Shadow]

Originally Posted by OzriderXR8

I'll take it a run shortly and see what it does at various speeds, gps and speedo.

Just done a freeway drive it was 2100 rpm @ 100kmph. In a ute, stock but for 4001 pacemakers @ bigmouth.

[T MAN]

Originally Posted by castellan

One thing you must do if you have messed with the exhaust is to get it tuned for it, as you will only loose power by exhaust alone and that's a fact !

If you want more torque change the cam, as that's the heart of the engine that rules such things.

you dont have to get it tuned for exhaust, nothing will change, the afrs wont change unless there has been a significant change of air or fuel coming into the engine, yes by changing the exhaust your letting the gasses out faster but it wont do much if there is no change of whats going into the engine.

[Crazy Dazz]

Gotta be honest, most of the above suggestions may improve top-end power, but won't do much for low-end torque.

A shorter diff ratio will effectively give you more torque at the back wheels, but at the expense of cruising economy.

You also need to consider your exact needs, because unless you have a load in the back, your ability to use that torque will be limited by your tyres.

You can tweak it a bit with a tune, but keep in mind that all you're really playing with is ignition and fuelling.

Originally Posted by castellan

If you want more torque change the cam, as that's the heart of the engine that rules such things.

Correct, if you really want to change the profile of an engine, the cam is where you start. I would imagine there are a heap of different options available ex-US (just make sure you look at roller cams).

Beyond that, the best way to boost low-end torque is with a small super-charger.

[castellan]

Originally Posted by T MAN

you dont have to get it tuned for exhaust, nothing will change, the afrs wont change unless there has been a significant change of air or fuel coming into the engine, yes by changing the exhaust your letting the gasses out faster but it wont do much if there is no change of whats going into the engine.

Carby engine all's ok but EFI you loose power, I had a new VS 5.0L 179KW commodore manual and a mate bought one just the same and we had runs in 3rd gear before he did the exhaust and mine was just a bit quicker then his, but when he got the full exhaust done, extractors and 3inch system he came out for another run and I hosed him off no problem, he thought he had more power because of the noise before hand, but the fact is he had lost power, he was so spun out at the time, that I just said to make him feel better that I had mine chipped and he totally believed mine had been chipped. but when he got his chipped he just blew mine away into the weeds.
Truth be tolled I wanted him to get it chipped and all so I could see the difference, I think he was only set on going for exhaust before that.

And another VT 5.0L SS had a full system and the other VT 5.0L SS was stock, fact is the stock hosed off the full system one that was not chipped.

Some poor bugger thinks exhaust works just like the old carby fed do is totally mislead. not to mention jetted correctly they do make more power.

[T MAN]

i can only go off my experience with tunning my xr8, going from factory cats with a single exhaust to a dual 2.5" system with 100 cel cats had no effects on the air fuel ratio or ignition timing, so there was nothing to tune in my case,
it did not kill any of the down low torque as some people claim and gained slightly in the top end.

[FTE]

Originally Posted by castellan

Carby engine all's ok but EFI you loose power, I had a new VS 5.0L 179KW commodore manual and a mate bought one just the same

That would have to be a ute? the 179 was released with VT so the only VS to receive the roller cam block was the ute (or optional 195i) otherwise it's the older 168 or 185.

[Sox]

Originally Posted by castellan

One thing you must do if you have messed with the exhaust is to get it tuned for it, as you will only loose power by exhaust alone and that's a fact !

Ah no, it's not.
Most of these Falcons run on the rich side standard, therefore improving exhaust flow, actually leans the AF ratio out by small amount, getting it closer to 'correct'.
Therefore producing more power, usually right across the range with a good system.

If you want more torque change the cam, as that's the heart of the engine that rules such things.

True enough, however there are many other things which can be changed to enhance certain rpm ranges.

Much of this has already been pointed out.

Originally Posted by Crazy Dazz

Gotta be honest, most of the above suggestions may improve top-end power, but won't do much for low-end torque.

Which is why I suggested a tri-y header with a smaller primary pipe. This will improve torque at lower revs, without a doubt.

A shorter diff ratio will effectively give you more torque at the back wheels, but at the expense of cruising economy.

Not by much though, I've shortened diff ratios on probably 20 different Falcons over the last 25 years.
Many of them had almost no change in economy.

You can tweak it a bit with a tune, but keep in mind that all you're really playing with is ignition and fuelling.

Sure, but pour 98 fuel in, and give it some more ignition advance, and watch those wheel spin.
A good tune, can make quite the difference.

Originally Posted by castellan

Carby engine all's ok but EFI you loose power, I had a new VS 5.0L 179KW commodore manual and a mate bought one just the same and we had runs in 3rd gear before he did the exhaust and mine was just a bit quicker then his, but when he got the full exhaust done, extractors and 3inch system he came out for another run and I hosed him off no problem, he thought he had more power because of the noise before hand, but the fact is he had lost power, he was so spun out at the time, that I just said to make him feel better that I had mine chipped and he totally believed mine had been chipped. but when he got his chipped he just blew mine away into the weeds.
Truth be tolled I wanted him to get it chipped and all so I could see the difference, I think he was only set on going for exhaust before that.

And another VT 5.0L SS had a full system and the other VT 5.0L SS was stock, fact is the stock hosed off the full system one that was not chipped.

Without knowing what kind of headers and exhaust was fitted, it really doesn't tell us much.
The header pipes may have been too big, the system might have been too big, there's too many variables here to make the blanket statement you made.

We're also not talking about a Commodore, rather a Windsor powered XR8, of which there's possibly hundreds on this very forum which have made nice gains just by changing headers and exhaust system.
Myself included.

Some poor bugger thinks exhaust works just like the old carby fed do is totally mislead.

Actually, without re-jetting a carby, it's more likely to drop power than an EFI system.

The fact is, both EFI and carby's need tuning to to optimise for every change, though EFI is a little adaptable without a tune.

[OzriderXR8]

Little run turned out to be a days shopping...

Ok, flat straight road.

90kph - 1750rpm
100kph - 1900rpm
110kph - 2100rpm

[Blue Shadow]

Originally Posted by OzriderXR8

Little run turned out to be a days shopping...

Ok, flat straight road.

90kph - 1750rpm
100kph - 1900rpm
110kph - 2100rpm

Same as me OZ

[castellan]

Originally Posted by FTE

That would have to be a ute? the 179 was released with VT so the only VS to receive the roller cam block was the ute (or optional 195i) otherwise it's the older 168 or 185.

Yes mine and mates were both 1999 model utes with 179KW, I missed out on getting the optional 195KW by then Dec 1999 as they were all gone so they said, but at the time I thought they were just the same engine as the 179KW so I was not bothered, if I only knew the 195 had a bigger cam and different exhaust valve I would of been p'ed off. I could of got the HSV Maloo with 195KW at the time.
I was happy going to do the exhaust and chip any road and could do it all cheaper, thinking it was just like the older engines that Holden just did exhaust mods and chip.

The first VS got the 165KW and then the ute from the time the VT sedan came out got the 168KW it only had a air snorkel and maybe a little different tune, but a bloke I know who had the 165 before his 168 claimed his old 165 performed better. the 185KW stayed the same.

The stock VT 179KW performed better than my stock 179KW ute because the ute only had the crappy single exhaust, so the fact is that them ute's did not truly have 179KW, Holden some how got away with claiming this. the ute should of got the twin exhaust as well.

[castellan]

Originally Posted by Sox

Ah no, it's not.
Most of these Falcons run on the rich side standard, therefore improving exhaust flow, actually leans the AF ratio out by small amount, getting it closer to 'correct'.
Therefore producing more power, usually right across the range with a good system.

True enough, however there are many other things which can be changed to enhance certain rpm ranges.

Much of this has already been pointed out.

Which is why I suggested a tri-y header with a smaller primary pipe. This will improve torque at lower revs, without a doubt.

Not by much though, I've shortened diff ratios on probably 20 different Falcons over the last 25 years.
Many of them had almost no change in economy.

Sure, but pour 98 fuel in, and give it some more ignition advance, and watch those wheel spin.
A good tune, can make quite the difference.

Without knowing what kind of headers and exhaust was fitted, it really doesn't tell us much.
The header pipes may have been too big, the system might have been too big, there's too many variables here to make the blanket statement you made.

We're also not talking about a Commodore, rather a Windsor powered XR8, of which there's possibly hundreds on this very forum which have made nice gains just by changing headers and exhaust system.
Myself included.

Actually, without re-jetting a carby, it's more likely to drop power than an EFI system.

The fact is, both EFI and carby's need tuning to to optimise for every change, though EFI is a little adaptable without a tune.

I agree you maybe correct in all that.

[Crazy Dazz]

Originally Posted by Sox

Not by much though, I've shortened diff ratios on probably 20 different Falcons over the last 25 years.
Many of them had almost no change in economy.

Depends on what you're doing. OP wants good economy for his drive to Adelaide. Shortening his diff will hurt that.

Originally Posted by Sox

Sure, but pour 98 fuel in, and give it some more ignition advance, and watch those wheel spin.

Cheaper to buy a new car, than run it on 98.

[BOTTLEDUP]

Highway mpg with my ratio swap from 3.45 to 3.91s improved. With the T5 in 5th I sit on around 2500 @ 110kmh.

The OP said he doesn't want to ruin the national economy, no mention was that that it needs BETTER economy than standard...

Headers, cats, diff gears & a proper retune of the ECU (not a mailorder chip) will be the best improvements you can do without ripping the engine apart.


Cheaper to buy a new car than 98 octane? WTF are you buying it by the super tanker?

[Sox]

Originally Posted by Crazy Dazz

Depends on what you're doing. OP wants good economy for his drive to Adelaide. Shortening his diff will hurt that.

As I've already said, I've shortened at least 20 Falcon diffs.
I know what it does to economy.

How many have you done?

Cheaper to buy a new car, than run it on 98.

I can run all my cars on 98 fuel for the next 30 years and still be cheaper than buying a new car.

[T MAN]

I also changed to 3.91 gears and there was no change in fuel economy around city or on the freeway.

[MrEL]

When i went to 3.9s in my old ute with the 5 speed around town economy improved and i used 0.5 of a litre more per hundred on freeway running.
The first thing ill be doing with the missus 5.0 AU when i seriously start to play with it will be diff gears.

[Crazy Dazz]

Originally Posted by MrEL

When i went to 3.9s in my old ute with the 5 speed around town economy improved and i used 0.5 of a litre more per hundred on freeway running.

Sounds about right.
As I said, it depends what the OP wants to use the car for.
Like many things in a car, gear and diff ratios are an exercise in compromise, trying to achieve the optimum balance. Ex-factory, Ford can only aim to cover the needs of most owners. In the past few decades they have probably tried to err on the side of reportable economy figures, rather than 0-100 times.

(That said, my XR4 is ridiculously short, if only changing FWD diffs was that simple.)

OP wants "more torque" and shortening his diff will give him more torque at the rear wheels. It will also hurt his highway cruising economy. Up to him if that is an acceptable compromise.

[MrEL]

To loose half a litre per hundred kms on the freeway is hardly a lose of highway economy. Especially overall when it improved 2 litres to the hundred around town.

[Blue Shadow]

Originally Posted by Crazy Dazz

Depends on what you're doing. OP wants good economy for his drive to Adelaide. Shortening his diff will hurt that.
Cheaper to buy a new car, than run it on 98.

I run mine on 98 I don't think its that much of a difference

[Bossxr8]

I didn't notice any loss of economy on the highway with 3.9's. Not enough to be noticeable anyway. Was better around town though and I did check the economy every time I filled to see.

[mcfly94]

Lets face it anything that is going to get the car moving better is going to cost fuel economy, except probably a tune, the rest is to go faster.

Get some 3.9's the fun makes up for the lighter wallet! Besides the btr gears ratios are crap! Speaking of that, convert it to manual! gears will feel even better then, and if you baby it would probably get even better fuel economy, or t56 conversion better again!

[Sox]

Originally Posted by mcfly94

Lets face it anything that is going to get the car moving better is going to cost fuel economy, except probably a tune, the rest is to go faster.

Actually no.

Shorter gearing typically requires less throttle opening to make a car accelerate at the same rate it did before.
Therefore using less fuel.

An engine that produces more torque at lower revs, will also typically use less fuel.
Again, due to lighter throttle opening for the same rate of acceleration.
Same goes for the highway, less throttle opening to maintain speed.

Naturally once you really want some get up and go, and you use that go, then you will start using more fuel.

The other common problem is, many people go too big on exhaust, cams and other things, only to make good power up top, but have lost a good amount down low.
They can suck fuel pretty hard.

Get some 3.9's the fun makes up for the lighter wallet! Besides the btr gears ratios are crap! Speaking of that, convert it to manual! gears will feel even better then, and if you baby it would probably get even better fuel economy, or t56 conversion better again!

Yeh the short first in the BTR sucks balls.

I reckon the manual doesn't really need shorter gearing for the road, at least not as short as the BTR.

[mcfly94]

Originally Posted by Sox

Actually no.

Shorter gearing typically requires less throttle opening to make a car accelerate at the same rate it did before.
Therefore using less fuel.

An engine that produces more torque at lower revs, will also typically use less fuel.
Again, due to lighter throttle opening for the same rate of acceleration.
Same goes for the highway, less throttle opening to maintain speed.

Naturally once you really want some get up and go, and you use that go, then you will start using more fuel.

The other common problem is, many people go too big on exhaust, cams and other things, only to make good power up top, but have lost a good amount down low.
They can suck fuel pretty hard.


Yeh the short first in the BTR sucks balls.

I reckon the manual doesn't really need shorter gearing for the road, at least not as short as the BTR.

Haven't met anyone that has done gears and drives the car softer and more sedately, sorry. I definitely didnt go 3.9 for better fuel economy and to drive my car like a grandma haha.

Shorter gears definitely make it fun and definitely no real down side, a mate of mine still pulls 260kmhr with a t56 and 4.11 so you definitely dont run out of legs haha, while first becomes extremely short, it cruises nicely if you need it to and can cruise at low rpm in 60/80 kmh zones, at 100km revs start getting up there but still better than auto rpm level.

I suppose another option is Miami swap, better fuel economy and power, win win.

[Sox]

Originally Posted by mcfly94

Haven't met anyone that has done gears and drives the car softer and more sedately, sorry.
I definitely didnt go 3.9 for better fuel economy and to drive my car like a grandma haha.

I understand that, but I didn't mean it that way.
If you drive it much the same as you did though, economy will likely improve.

The same throttle input as before will have you accelerating slightly better.
The car has become more efficient.

Shorter gears definitely make it fun and definitely no real down side, a mate of mine still pulls 260kmhr with a t56 and 4.11 so you definitely dont run out of legs haha, while first becomes extremely short, it cruises nicely if you need it to and can cruise at low rpm in 60/80 kmh zones, at 100km revs start getting up there but still better than auto rpm level.

Yeh, a 6spd helps lots here.
You can always find the right gear easily.

I suppose another option is Miami swap, better fuel economy and power, win win.

Meh, I'd rather my trusty simple little Windsor any day.

[ebv8]

i tried all the generic bolts on to get more from my old AU3 XR8 but gears would have been the best thing, I have full exhaust with pacemaker 4-1 and hi flow cats, CAI but it was auto and was a bit of a dog unless you were 3500rpm plus but them it would run off power at 5500rpm.
in my old EB 5l i did a cam and 3.9 gears and that would have smashed the AU anyday.

[Bossxr8]

Originally Posted by mcfly94

Lets face it anything that is going to get the car moving better is going to cost fuel economy, except probably a tune, the rest is to go faster.

Get some 3.9's the fun makes up for the lighter wallet! Besides the btr gears ratios are crap! Speaking of that, convert it to manual! gears will feel even better then, and if you baby it would probably get even better fuel economy, or t56 conversion better again!

After I had done diff gears, Explorer intake, TB and MAF, extractors, exhaust, diff gears, underdrives and tune I was getting economy about 2 litres per 100 better than what I was getting stock. Just casual driving around the suburbs. If you are making the engine more efficient there is no reason why economy shouldn't improve during regular driving.

[OzriderXR8]

Originally Posted by Bossxr8

After I had done diff gears, Explorer intake, TB and MAF, extractors, exhaust, diff gears, underdrives and tune I was getting economy about 2 litres per 100 better than what I was getting stock. Just casual driving around the suburbs. If you are making the engine more efficient there is no reason why economy shouldn't improve during regular driving.

Explorer intake?