Launch RPM?

by **FairmontXR6** » October 20th, 2008, 9:43 pm

krisisdog wrote:Bah, I need something other than stock 3.08 gearing then lol. 2nd does just over a hundred atm, but it does get there pretty quick .
Was thinking of 3.7s rather than 4.11s as I do a bit of hwy driving, and I dont have a 6spd , otherwise I probably would get 4.11s, and also getting a locka rather than an LSD. $$$ either way.

Most people don't go over 3.45s with manuals for their daily driver. Let us know how you go.

by **krisisdog** » October 20th, 2008, 9:49 pm

Yeh, but Ive been in an XR6 5spd, and the difference between that and mine now was fairly minor, which is why I'm thinkin 3.7s..... mmaybe even 3.9s.

by **TWR40T** » October 20th, 2008, 9:50 pm

hey whats wrong with auto's lol
I converted after i blew a couple of manuals...and my clutch pedal is still tucked up under the carpet lol
(rushing before powercruise & i still havent taken it out lol)

by **TWR40T** » October 20th, 2008, 9:52 pm

I goto about 2500...the brake pedal gets a bit hard to hold thought because ive lost a bit of vacuum because of the cam.

by **BROCKYB8** » October 21st, 2008, 6:44 am

WELL kris i just bought a 411 diff ill let you know what its like onm hwy .
Lucky for my ea brock isnt a daily .

by **holmsy** » October 21st, 2008, 12:47 pm

3.45's make first gear very short. i would hate to even think what 4.11's would do.

by **BROCKYB8** » October 21st, 2008, 12:56 pm

well we will find out . Plus i got a few more revs then most to play with ,

by **Steady** » October 21st, 2008, 5:03 pm

4.11s is getting too short with a later model t5 let alone an EA box.

by **AaronEF8** » October 21st, 2008, 5:22 pm

A while ago I experimented with a drag simulator using a street-driven 150rwkw EA I6 (using a dyno graph to graph the power curve) with an EF T5 and changing diff ratios between available variants. 3.45 was the quickest time, 3.23 was the fastest MPH, and 4.11s run the same speed as a 2.77, although the 2.77 had a higher MPH because the 4.11s put the engine on the limiter 50m before the finish line.

by **BROCKYB8** » October 21st, 2008, 5:48 pm

oh well we will see what happens.
I have done this on what my mechanic has suggested .
But u also got to remember its gotta go on what the size of the wheels are too.

by **AaronEF8** » October 21st, 2008, 6:42 pm

But u also got to remember its gotta go on what the size of the wheels are too.

Yep thats right, so you're using 29" slicks?

by **OED666** » October 21st, 2008, 6:54 pm

Steady wrote:4.11s is getting too short with a later model t5 let alone an EA box.

oh yea.. my original manual conversion was with an EA box, and I already had 3.9's. 1st was useless. Then I got a T5Z, and it was much better.

The first 4 ratio's of a T5Z is very similar to my 6 speed.

by **Mr. CVE** » October 21st, 2008, 7:36 pm

AaronEF8 wrote:
But u also got to remember its gotta go on what the size of the wheels are too.

Yep thats right, so you're using 29" slicks?

you were close !! he was running 27" slicks !!

different cars, different combos different styles.
std radial tyres, not many revs. but in brocky's car, as we had drag radials, 4-4500 and ride the clutch, yes it slips for a split second but it works. that style won me the go-whoa, which was a round robyn style, so i had to back it up in less than 5 mintes, if the clutch was sad it would not have coped ( cooled) in time.
Back in the day when I had my Falcon XA coupe drag car, that was manual and that style could almost lift the front wheels. LTDHO would remember !! His coupe also was the same.
also as LTDHO cams and powerbands make a bif difference as well, and manual and a turbo, harder again !!

Good luck !!

by **oneredED** » October 21st, 2008, 7:50 pm

Rollin wrote:
oneredED wrote:I ended up with my dash mat on my lap and the fuse cover sitting on the floor at one stage

Nice work I've only managed the fuse cover trick once haha. Do you superglue your interior light cover on?

Hmm, can't say I remember that one coming off haha. I did end up pulling the gear knob off once though... stupid aftermarket knobs and their shitty hex grubs.

by **holmsy** » October 21st, 2008, 10:30 pm

i get the boot and fuel cap buttons to come out and hang there.

by **BROCKYB8** » October 22nd, 2008, 8:34 am

iM guessing we will see how i go when i take it down the track .
Thats the only way to get a definate answer i reckon

by **EL XR8** » October 22nd, 2008, 9:17 pm

4.11's are average in a manual.
Nearly 3,000rpm at 110km/h. Just stupid really.
If you do any hwy driving, i wouldn't even think about them.

by **NUT347** » October 22nd, 2008, 10:02 pm

lol when i first chucked the manual in my eb i had 3.7s. first was 35, second 75, 3rd 110, 4th 150, 5th no idea. sat on 2800@100. useless... first gear was useless. i pulled the diff out and put 3.2s back in. 3.45 is the highest id go for manual, unless you have a t56

by **Rollin** » October 23rd, 2008, 12:19 am

You must have an EA box or something - I had 3.9s in my EB XR6 (factory manual) and it sat on 2k@100km/h if I recall correctly...might have been 2100?

Bit ghey if you like to cruise at 120km/h but still got ok fuel consumption surprisingly, and the around-town drivability was excellent

by **Gozza** » October 23rd, 2008, 9:14 am

i think this thread is a bit unrealistic - Mods - Tyres - Wheels - Track conditions - Human Error - everything contributes to a good or bad launch

Go and do lots of runs and take notice what your doing - try somthing different - learn your car.

by **krisisdog** » October 23rd, 2008, 11:45 am

Rollin, what size wheels were you running?
I sit on 2k rpm at 100 with the stock 3.08, and stock 15"s. I dont think theres that much difference in the EA ratios...

by **BROCKYB8** » October 23rd, 2008, 12:12 pm

WELL i think thats why we all have different ideas of what works.

by **Mr. CVE** » October 23rd, 2008, 2:29 pm

Gozza wrote:i think this thread is a bit unrealistic - Mods - Tyres - Wheels - Track conditions - Human Error - everything contributes to a good or bad launch

Go and do lots of runs and take notice what your doing - try somthing different - learn your car.

exactly, every combo is different

by **Barnsy** » October 23rd, 2008, 5:56 pm

Based on the following ratios rpms @ 100km/h (225/50/R16 rims) with T5
2.77 - 101.43km/h @ 1,700rpm
2.92 - 101.88km/h @ 1,800rpm
3.08 - 101.95km/h @ 1,900rpm
3.23 - 99.77km/h @ 1,950rpm
3.27 - 101.08km/h @ 2,000rpm
3.45 - 100.60km/h @ 2,100rpm
3.73 - 101.91km/h @ 2,300rpm
3.9X - 101.70km/h @ 2,400rpm
4.11 - 100.53km/h @ 2,500rpm

2500rpms at 100km/h ain't that bad, the only problem is that the speed limited cut out at 4,000rpms

by **FairmontXR6** » October 23rd, 2008, 7:11 pm

My Auto with 4.11LSD on 205/65R15 equals
90km/hr in 4th = 1950RPM
100km/kr in 4th = 2100RPM
110km/hr in 4th = 2300RPM

by **Mr. CVE** » October 23rd, 2008, 8:43 pm

You guys are spoilt, in the old days, the std xd 302 setup, 2500 rpm was 100 kph !!
life before overdrives !!

by **Barnsy** » October 23rd, 2008, 9:25 pm

FairmontXR6 wrote:My Auto with 4.11LSD on 205/65R15 equals
90km/hr in 4th = 1950RPM
100km/kr in 4th = 2100RPM
110km/hr in 4th = 2300RPM

Based on my calculations an auto with 4.11 with 205/65/R15
with auto gearing of 2.39, 1.45, 1.00, 0.68
90km/h 4th = 2080rpm
100km/h = 2300rpm
110km/h = 2520rpm

FairmontXR6, it seems you may have a 3.73 ratio, according to my calculations:
90km/h 4th = 1875rpm
100km/h = 2080rpm
110km/h = 2287rpm

by **FairmontXR6** » October 25th, 2008, 9:06 am

Did your calculations take into the effect of the Lock-Up Torque Convertor? (Reduces RPM once it has locked)
Since the torque convertor locks at those speeds, I chose to give those RPM readings.
(I have 4.11s in my diff, as I put them in with the help of a diff specialist.)

by **edfairmont4.0** » October 25th, 2008, 11:16 am

Weird, barnsy, your calculations are spot on. Thats exactly what my car revved at with 4.11's. Fairmontxr6 locked torque converter doesnt change your gear ratio.. the 4th is still .68 my revs were slightly higher but when it locked 2300RPM was 100. and it matched up to all my calculators as well. i wanna see your speedo at 110 reading 2300.... Unless you speedo is wrong. Sit next to my car on the freeway mine is dead on.

by **FairmontXR6** » October 25th, 2008, 6:26 pm

edfairmont4.0 wrote:Weird, barnsy, your calculations are spot on. Thats exactly what my car revved at with 4.11's. Fairmontxr6 locked torque converter doesnt change your gear ratio.. the 4th is still .68 my revs were slightly higher but when it locked 2300RPM was 100. and it matched up to all my calculators as well. i wanna see your speedo at 110 reading 2300.... Unless you speedo is wrong. Sit next to my car on the freeway mine is dead on.

by **Barnsy** » October 25th, 2008, 6:40 pm

You have a PM

by **FairmontXR6** » October 26th, 2008, 7:55 pm

Aha! Found out what happened. When I copied the info of my car that I have put into an Excel document, I had the wrong RPM next to the wrong KM/HR.
:oops:

I did a road test today, below are images of the dash at 80, 90, 100 and 110km/hr.

by **NUT347** » October 26th, 2008, 8:14 pm

lucky you dont have a 3 speed :oops:

by **Barnsy** » October 26th, 2008, 9:04 pm

The 3 speed is pretty much exactly the same except without overdrive (4th), but cruising down the highway at at 100km/h @ 3500rpms would eat into the fuel!

by **needfordspeed** » October 26th, 2008, 9:04 pm

rofl, what's with the sticker saying "behave" hahah

by **NUT347** » October 26th, 2008, 9:16 pm

needfordspeed wrote:rofl, what's with the sticker saying "behave" hahah

lol if you met him, you would understand

he goes down main roads in first gear in and out of cars constantly, we now have named him "limiter"

by **edfairmont4.0** » October 26th, 2008, 9:37 pm

AHAHHAHAHAHHAHAHHAHAHAHAHHAHAHA

by **FairmontXR6** » October 26th, 2008, 10:08 pm

needfordspeed wrote:rofl, what's with the sticker saying "behave" hahah

Because every now and then I need to check to see if the rev limiter works in my car,

.
The idea of the sticker is to remind myself to 'behave'. Doesn't work well. If it did work, I would have remembered to cut it out of the pics LOL.

by **edfairmont4.0** » October 27th, 2008, 6:53 am

lol yes its very common for the rev limiters to stop functioning isnt fairmontxr6 :lol:

i can only go near my limiter on the freeway lol i hit the limiter at about 95km/h

by **ClassicAU** » November 28th, 2008, 1:19 pm

With regard to short diffs and T5's, when I first did the conversion in my AU, I still had 3.73 diff ratio. I did a trip up to Sydney in it with two mates, and with the AC on all the way and cruising about 110km/h, managed to make it from Reservoir in Melb, to the outer suburbs of Sydney on one tank of premium!! Now that I have gone back to 3.08 ratio, I have a feeling the economy is actually worse! Definitely worse around town anyway.

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