AUII XR8 200kw - Torque Increase

[Bossxr8]

AU intake manifold. Get's referred to as the Explorer cause that's where it was first used, but it's essentially a production version of the Cobra manifold.

[meanfalcon]

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.
_____

I have put Pacemaker 4006, big cats and twin 2 1/2" exhaust on my AU 220kw in preparation for other mods and now it runs rough and back fires. Will a tune have it run smooth again?_____________

[T MAN]

if it now runs rough and backires something else is wrong like a vacuume hose off or a 02 sensor maybe isnt plugged in?'

i had mine with a single 3" system with factory headers, aftermarket cats, i got done for a epa check and i had to make it as quiet as stock so added factory cats and stock mufflers, then once that was done i went to hurricane headers, 100cel cats and a dual 2 1/2 inch system and other than the stock mufflers restricting performance there was no change in how the car idled or ran with the 3 different set ups..

[meanfalcon]

Thanks T Man,

I will check my O2 plugs as particularly on the drivers side they can be awkward.

Pacemaker don't recommend using their 4 - 1 headers unless the engine is a stroker or supercharged. I am wanting to get the PD blower on it. I have a big pod filter intake as well, and have checked for vacuum leaks but i will check the exhaust sensors.

Mike

[OzriderXR8]

Thanks for all your input.

When I bought the car they told me there had been some mods done but I have never received any paperwork. I have no idea if the headers are standard or not.

It has an SS Induction cold air intake fitted, I've just put a 2.5 inch single mandrel bent cat back exhaust on and I'm going to measure the TB etc today as they tell me it's a 70mm (doubt it).

I've never changed a car diff before, Is it difficult?

I need to change the diff seal anyway is it is weeping.

SS Induction Intake







Headers





Throttle Body

[Blue Shadow]

Don't think they are factory, if you look on the flange sometimes there are identifiers

[mcfly94]

They are some from of standard headers.
The tb is a standard 65mm option.
AU IRS diff is one of the easiest diffs to change (unlike the stupid irs commodore!)

[OzriderXR8]

Originally Posted by mcfly94

They are some from of standard headers.
The tb is a standard 65mm option.
AU IRS diff is one of the easiest diffs to change (unlike the stupid irs commodore!)

Do I need to change anything else if I replace the TB?

Spacer, MAF etc?

[mcfly94]

Depending on the TB, probably spacer, custom accel bracket, mod tb to suit RHD aus windsor.
Why do you need to replace it?

[BOTTLEDUP]

Factory headers & cats, and standard 65mm throttlebody is what I see in those pictures.

If you're after an increase in torque & throttle response try the smaller primary Tri-Y headers from a manufacturer such as Hurricane or Advance. Coupled with a pair of freeflowing cat converters you will see some improvements but by far and away the biggest gain will be from diff gears.

[OzriderXR8]

Just measured the TB, it's 69.1 as per my crude drawing. ???

[mcfly94]

measure the butterfly

[Blue Shadow]

Mcfly whit size are you putting on the LTD, should OZ do the same?

[mcfly94]

Originally Posted by Blue Shadow

Mcfly whit size are you putting on the LTD, should OZ do the same?

90mm, most definitely not, thats to suit 408 cubes 200cc plus heads, victor efi manifold (which will be ported)
Depending what your doing with the car you may not need to upgrade.
If your doing HCI you could look at a 70-75mm
80mm if its really going to be breathing!

[Blue Shadow]

Then yours should be one of the quickest LTD around :-)

[mcfly94]

Originally Posted by Blue Shadow

Then yours should be one of the quickest LTD around :-)

LTD maybe, lane no, have to build a bb to keep up with Vitos lane! think his aiming to push 9's in full street trim

[OzriderXR8]

Originally Posted by mcfly94

measure the butterfly

I just happened to have a strip of aluminium that was 65mm wide, I could slide that all the way into the butterfly and it was pretty loose.

Not all that fussed, just checking considering I was told it was 70mm when I bought it.

[Blue Shadow]

Originally Posted by mcfly94

LTD maybe, lane no, have to build a bb to keep up with Vitos lane! think his aiming to push 9's in full street trim

Neck snapper

[Blue Shadow]

Originally Posted by OzriderXR8

I just happened to have a strip of aluminium that was 65mm wide, I could slide that all the way into the butterfly and it was pretty loose.

Not all that fussed, just checking considering I was told it was 70mm when I bought it.

Wouldn't worry about it champ unless your going to to alot of other stuff to it.

[T MAN]

i think the single 2.5" system is to small for the 200kw 5.0..
should have gone a single 3" or duel 2.25 at a minimum, as the factory dual 2.25" system is more free flowing than a single 3" system let alone a single 2.5"

[STINKY NINJA]

Originally Posted by OzriderXR8

Just measured the TB, it's 69.1 as per my crude drawing. ???

image

That drawing is incorrect,the throttle blade sits on a stepped down shoulder,just over 65mm,yes the outer diameter is 69mm but it steps down to 65 around 5mm in front of the throttle blade.
If you remove it and measure the rear entry its 65mm;)
I just went and measured up the spare I have in the shed.

[Sox]

Originally Posted by T MAN

i think the single 2.5" system is to small for the 200kw 5.0..
should have gone a single 3" or duel 2.25 at a minimum, as the factory dual 2.25" system is more free flowing than a single 3" system let alone a single 2.5"

The 2.5" single won't really hurt for what he's chasing, but yeh, he'd be better off overall with twin 2.25".

BTW, factory is actually twin 2.25 to the diff, then twin 2" past the diff.

[STINKY NINJA]

Theres a lot of chatter about pacies vs hurricane etc,inch and a half vs inch and 5/8 primary size making a lot of difference to low end torque,would it even be noticeable?
Has anyone ever done back to back tests or does anybody have dyno results to prove this,id love to see them.

[STINKY NINJA]

Pacie has bigger primary and secondary but a 2 1/4 collector,hurricane has smaller primary and secondary but a 2.5 inch collector,you would need some decent hp to be making use of a 2 1/2 collector on a 5.0 but tbh how would one be better than the other,one has slightly faster gas speed leaving the head and slowing down at the big collector the other the total opposite,how can the hurricanes be better?
A lot of exhausts on high hp cars ive seen has a step down after the collectors,is this to speed up exhaust flow?
Is exhaust gas speed more critical to making torque as its leaving the head or nearing the collector?

[Sox]

Originally Posted by STINKY NINJA

Theres a lot of chatter about pacies vs hurricane etc,inch and a half vs inch and 5/8 primary size making a lot of difference to low end torque,would it even be noticeable?

Absolutely it's noticeable.
However, many times people are looking in the wrong places, that is, peak power.

Peak numbers are only a tiny part of the story, and the least important.
Power under the curve, and part throttle response are much more important as that's where the vast majority of our driving is spent.
The area between (say) 5000rpm and 6000rpm is only a tiny portion of the engines range we use, and for the least amount of time.
Yet these are the numbers most seem to focus on. Bragging rights. Go figure.

Has anyone ever done back to back tests or does anybody have dyno results to prove this,id love to see them.

Sure, but not much is documented.
There are a few articles showing pipe diameter differences, they are very informative, and an eye opener to bigger is better crowd.

Originally Posted by STINKY NINJA

Pacie has bigger primary and secondary but a 2 1/4 collector,hurricane has smaller primary and secondary but a 2.5 inch collector,you would need some decent hp to be making use of a 2 1/2 collector on a 5.0 but tbh how would one be better than the other,one has slightly faster gas speed leaving the head and slowing down at the big collector the other the total opposite,how can the hurricanes be better?

Because what happens immediately after the port is the most important.
Secondary's and then collectors are important, but not as.
Pipe length is also very crucial, of both primary and secondary.

A 2.5" collector is ok for a 5L, particularly at that point, where the exhaust gasses merge and are hot.
So long as it steps down to 2.25" at some point where it's cooler to keep velocity high.
Exhaust gas shrinks as it cools.

A lot of exhausts on high hp cars ive seen has a step down after the collectors,is this to speed up exhaust flow?

My pursuit has headers made like this, the primary pipe exits the port at 1 5/8 for around 200mm, then steps back to 1 1/2" for another 200mm.
Then into looong 2" secondaries, and onto 2.5" collector.
This then steps down again to 2.25" at the diff.
Gas velocity remains high from port to tip.

Is exhaust gas speed more critical to making torque as its leaving the head or nearing the collector?

From the port is most important, but it all plays a part.
Like all parts of an engine, it's only as strong as the weakest link.

Pipe diameters should remain as small as possible to cause minimal restriction at the engines highest RPM.
This keeps velocity at it's highest.

A 5% loss at 6000rpm is more than acceptable for a gain of 15% in the midrange, yet time an time again systems which are too big are fitted.
It happens more than you can imagine, and plenty of exhaust places won't acknowledge it because you've just outlaid $3000 on that big bore system.

Most people seem to think that everything from the race track will work on the road. It doesn't.

[mcfly94]

Id love to have a stocker 302 to see with hurracaine headers, 100 cell cats and 2.25 twin exhaust setup to see what it is like on the street, everyone raves about it, might use mums xr8 to test the theory as she wants a better exhaust as the single 3" is beginning to rust!

[STINKY NINJA]

Im sceptical,i can understand the theory but until I can see actual proof,heresay isn't enough for me anymore,ive been sucked into heresay too many times on this forum and it can get expensive...nobody puts there hand up when you've outlayed the cash and it doesn't make the power or doesn't work at all....
I don't mean general articles about extractor operation/ theory I mean comparisons on 5.0 litre efi windsors,thats what im specifically asking about.
Anyone can jump onto old hotrod mag articles from the states but they mean nothing in the real world on our motors in aus.
When I got my car tuned I was told my hitech extractors were a major restriction and they are identical pipe size to hurricane apart from the 2 1/4 collector,that was on a 205 rwhp tune.
I was told to get pacies by the tuner and the dyno operator,if hurricanes are that good why wasn't I recommended to buy them?
They both said the primary pipe size was too small.
Just saying,id love dave to jump in here,he always raves about hurricanes.
I hate to say it but a lot of the 5.0 efi info that gets around is third hand from us articles and not from first hand experience

[T MAN]

Im running hurricanes on a supercharged 5.0 and there is enough flow for it to make near 300rwkw

[STINKY NINJA]

That's awesome dude but im not on about blown windsors.
Your motor makes a ton more bottom end torque than a 5.0 with just an exhaust,its a bad comparison.
Id love to hear from someone that has changed from pacies to hurricanes and can prove they blow them out of the water with the mountains of extra low end torque they produce.
The seed was planted by the guy who tuned my car,im no exhaust expert,i just like proof before outlaying cash thesedays!

[T MAN]

True. But if they were considered a restriction on a n/a engine they would in theory be a huge restriction with a blown engine.