ED XR6 vs ED XR8

BlackEDXR61993 · 12-07-2012, 02:36 PM

Hi Guys I am new to the forums.

I was wondering what mods would be needed to make and ED XR8 start to beat an ED XR6 that already has Extractors and a good exhaust? Also would these mods hamper fuel economy or better it?

BHDOGS · 12-07-2012, 02:48 PM

exhaust and extractors should make it more fuel efficient but people have a tendency to rev it due to the better noise and ruin that haha

RAPID_BA · 12-07-2012, 02:56 PM

just get the diff gears upgraded to 3.45 ratio like XR6 and done. You have more power and torque in the 8 and at a wider power band and the ratios are now level.

b0son · 12-07-2012, 03:46 PM

Quote:

Originally Posted by HULK_BA

just get the diff gears upgraded to 3.45 ratio like XR6 and done.

and then what? the diff ratio argument would be correct if we knew what speed the owner was going to race to..... a shorter diff will be quicker over some intervals, slower over others.

RAPID_BA · 12-07-2012, 04:06 PM

Quote:

Originally Posted by b0son

and then what? the diff ratio argument would be correct if we knew what speed the owner was going to race to..... a shorter diff will be quicker over some intervals, slower over others.

with same ratios and more power and more torque the 8 should be quicker at any given speed. Any weight disparity is offset by the better low end torque of the 8, as speeds rise, weight is less of a factor. same ratios and the V8 is the winner.

b0son · 12-07-2012, 04:44 PM

Quote:

Originally Posted by HULK_BA

with same ratios and more power and more torque the 8 should be quicker at any given speed. Any weight disparity is offset by the better low end torque of the 8, as speeds rise, weight is less of a factor. same ratios and the V8 is the winner.

weight remains a factor always (i didnt make that up, the universe decided that long before you or I were around). low end torque is a factor for the first second or two, after that, you're spending all your time above 3500-4000rpm.

XRGhia · 12-07-2012, 03:11 PM

It's an ED XR8 hulk, it's already got 3:45, same as the XR6

wulos · 12-07-2012, 03:33 PM

/me shakes head at HULK BA - Back to the desktop racing my friend.

Might I suggest a course in power to weight, as well as comparing complete gear ratios (not just diff)

The ED XR8 came from the factory with 3.27, the XR6 with 3.45. The manual g/boxes between the XR6, & Xr8 had different ratios. The Auto boxes were identical between 6 & 8.

prydey · 12-07-2012, 07:43 PM

Quote:

Originally Posted by wulos

/me shakes head at HULK BA - Back to the desktop racing my friend.

Might I suggest a course in power to weight, as well as comparing complete gear ratios (not just diff)

The ED XR8 came from the factory with 3.27, the XR6 with 3.45. The manual g/boxes between the XR6, & Xr8 had different ratios. The Auto boxes were identical between 6 & 8.

umm, and do you have those ratio's to hand??

the 8 box has very similar 1st and second gears and a shorter 3rd. changing the diff makes the overal ratio shorter.

i believe what hulk has suggested is correct.

the OP wasn't asking how to do a 14sec 1/4.

to jog the memory of some..

Quote:

Originally Posted by BlackEDXR61993

what mods would be needed to make and ED XR8 start to beat an ED XR6

i think diff gears offer good value for money on these cars. i would add a full exhaust system as well, nothing over the top (twin 2.25 or single 3 would do) and you would have a very nice cruiser with a decent bite when needed.

wulos · 12-07-2012, 08:18 PM

Quote:

Originally Posted by prydey

umm, and do you have those ratio's to hand??

the 8 box has very similar 1st and second gears and a shorter 3rd. changing the diff makes the overal ratio shorter.

i believe what hulk has suggested is correct.

the OP wasn't asking how to do a 14sec 1/4.

to jog the memory of some..

i think diff gears offer good value for money on these cars. i would add a full exhaust system as well, nothing over the top (twin 2.25 or single 3 would do) and you would have a very nice cruiser with a decent bite when needed.

http://www.fordforums.com.au/photos/...php?photo=4762

prydey · 12-07-2012, 08:29 PM

Quote:

Originally Posted by wulos

http://www.fordforums.com.au/photos/...php?photo=4762

so having that info at hand, why would you 'shake your head at hulk' in your first post??

RAPID_BA · 12-07-2012, 09:08 PM

The easy comparison is to look at au xr8 185kw vs au xr6..

They fit the 3.45s to au xr8 and suddenly its quicker than xr6 and holden 5.0v8

Sure the au xr8 has a few kw more but only at redline. Compared to previous xr8s the 3.45 gears was the big kicker in performance.

Fit the 3.45s to pre au xr8s and a decent exhaust and you basically have au xr8 185kw equivalent performance. (quicker than a xr6)

Yellow_Festiva · 12-07-2012, 03:50 PM

I remember there wasn't much between the 6 and 8 kw wise (something like 157kw and 165kw??) but what about torque??

8 would have weighed a little more as well I assume.

RAPID_BA · 12-07-2012, 04:05 PM

The OP didnt mention auto or manual.

I assume the OP is talking about minimal mods to beat the XR6. Otherwise people would say, stroke it then supercharge it and then it will beat a ED XR6. We are talking about minimal mods.

Change diff gears and it will do the job on the XR6. The Gli 6 cyl has the same ratios as XR8 and guess what.....its slower than the 8. 3.45s in the XR6 and bingo its got more performance. Dont fool yourself to think the extra 4kw in the XR6 motor makes all the difference over the GLi.

ED XR8 has 3.27s. Put the 3.45s in the XR8 ED and it will beat the XR6. I know first hand. Ive put this ratio in 3 windsor V8s, EB, EF and EL 165kw motors. Ive also owned a EL Ghia (with XR6 3.45 diff and Xr6 motor). The 8 with the diff gears and all other mods equal will take out the XR6 ED.

Currently drive a 96 LTD 5.0 with 3.45s and extractors/cats/exhaust/intake. It will take out the EL ghia with same mods and same diff gears.

BlackEDXR61993 · 12-07-2012, 04:02 PM

161 kw 365.5 nm XR6. XR8 165kw 388 NM. I know from wheels mag Write up done on the EB XR6 vs EB XR8 they reckoned the XR6 was only 7kg lighter whether that's true I dont know. This Comparo is auto to auto btw.

BlackEDXR61993 · 12-07-2012, 04:21 PM

Standard ED GLI 148kw 348 NM vs 161KW and 365 NM that is quite a noticable difference and its alot more then a gear ratio.

Revised Porting for improved gas flow,Boost in Compression and change in camshaft profile and timing along with upgraded valve springs and increase in fuel pressure from 300kpi regulator. The ECU was also reprogrammed in them for more power and sharper shifts (for automatic).

Not saying that an XR8 with the same ratios wont be an XR6 but I am saying that you cant put a GLI in the same category as an XR6. the motors are very different.

Eaturbo · 12-07-2012, 07:08 PM

If you compare the 2 with the same gearbox than the xr8 only needs extractors and exhaust and decent air intake plus a bigger maf. My mate had an EB XR8 and it whipped out a 14.4 quarter which was fast enough to blow off xr6's and the VN to VS SS commodores. Those that have the EB/ED XR8 manuals would already know that they respond well to mods. The small HO manifold and E7 Heads give great torque due to the high air speed at low revs even though they fall over up top due to the same reason

XR Martin · 12-07-2012, 07:24 PM

These are now 20 year cars and the biggest factor will be which is in better mechanical condition.

BlackEDXR61993 · 12-07-2012, 07:43 PM

Hey Martin do you still have any of the old wheels/motor mags from EB/ED vintage.

Bossxr8 · 12-07-2012, 08:39 PM

Going from a 3.23 to a 3.45 diff ratio does bugger all, its hardly even worth doing cause the difference is so small. Better off going to a 3.7 or 3.9 that will make a huge difference.

But a good cold air intake, filter, extractors and exhaust will have the 8 killing the 6 for minimal dollars. A proper low diff ratio isn't needed but certainly worth doing.

RAPID_BA · 12-07-2012, 09:12 PM

Quote:

Originally Posted by Bossxr8

Going from a 3.23 to a 3.45 diff ratio does bugger all, its hardly even worth doing cause the difference is so small. Better off going to a 3.7 or 3.9 that will make a huge difference.

But a good cold air intake, filter, extractors and exhaust will have the 8 killing the 6 for minimal dollars. A proper low diff ratio isn't needed but certainly worth doing.

I have fitted 3.45s from 3.23s on a few windsors, feels heaps more torquey. Trust me its better than fitting a full exhaust on these cars. A diff geared windsor with stock exhaust will spank a full exhaust windsor with stock gears. (and beat a xr6 ed)

Bossxr8 · 12-07-2012, 09:40 PM

Quote:

Originally Posted by HULK_BA

I have fitted 3.45s from 3.23s on a few windsors, feels heaps more torquey. Trust me its better than fitting a full exhaust on these cars. A diff geared windsor with stock exhaust will spank a full exhaust windsor with stock gears. (and beat a xr6 ed)

The difference between a 3.23 and a 3.45 is numerically very minimal.

Try driving one with 3.7 or 3.9's and then come back and comment. Makes a real difference, not a barely noticable one.

prydey · 12-07-2012, 09:43 PM

hulk owned one with 3.9's.

RAPID_BA · 12-07-2012, 09:55 PM

Quote:

Originally Posted by Bossxr8

The difference between a 3.23 and a 3.45 is numerically very minimal.

Try driving one with 3.7 or 3.9's and then come back and comment. Makes a real difference, not a barely noticable one.

Ive driven them with 3.23s 3.27s, 3.7s, 3.9s.

I found the 3.45s or maybe 3.7s best overall. takes off well enough with 3.45s or 3.7s whilst keeping some legs as well for highway. They dont rev out too hard so dont wanna shorten them up too much. 3.9s will obviously take off harder but id say need some cams and revs to keep some legs. Will pay a bit more on the highway with 3.9s, but brutal off a set of lights. not everyones cup of tea.

But the question OP asked is what is required to walk away from ed xr6. 3.45 diff gears will do the trick, 3.7s and 3.9s make a mockery of the xr6 ed

prydey · 12-07-2012, 10:25 PM

Quote:

Originally Posted by HULK_BA

Will pay a bit more on the highway with 3.9s,

yep, driving a eb v8 with 3.9's from sydney back to adelaide (via bathurst) is not a journey i'll forget in a hurry. had a ringing in my ears long after my head hit the pillow. lucky to get 400km to a tank

b0son · 12-07-2012, 10:41 PM

Quote:

Originally Posted by HULK_BA

But the question OP asked is what is required to walk away from ed xr6. 3.45 diff gears will do the trick, 3.7s and 3.9s make a mockery of the xr6 ed

To what speed? What you gain over one interval, you lose over another.

http://forums.bimmerforums.com/forum...d.php?t=121351

Three different ratios simulated, the tallest ratio is quickest to 40pmh and 100mph. Over a longer run, they all even out.

Diff ratios are a game of swings and roundabouts - you never get a free lunch.

Of course, if you want to be the quickest from one set of lights to the next, by all means ... but in gear, on freeway for example, probably a different story.

**ebxr8240** · 12-07-2012, 09:14 PM

I still own both cars,,Yes the ratio is taller on the V8..
Yes 3:7 would be better option given that most these cars have
17" wheels on them now..
Changing heads [GT P's] and MAF would be my next option...
Atleast a good set of valve springs given the age...

Bossxr8 · 12-07-2012, 09:44 PM

Then he should know.

prydey · 12-07-2012, 09:46 PM

he does. he isn't saying that 3.45's are better than 3.7's or 3.9's.

wulos · 12-07-2012, 10:26 PM

From the factory sheets, for stock standard engines..
1528kg / 161 kw = 9.49kg per kw.
1573kg / 165 kw = 9.53kg per kw.
Without adding any potential benefits on the XR6 provided by extractors / exhaust(OP does mention that the XR6 has exhaust mods) the XR6 already has a better power to weight ratio(at 4500rpm) then the XR8, even if the gearing was identical.
The fastburn heads in the Tickford XR6 heads respond well to exhaust mods. Unless the exhaust / extractor combo fitted is a complete abortion I am confident that the XR8 would need a bit more than merely levelling the gears.
Personal experience with both of these vehicles in confirmation enough for me.