haha.. Yeah I know. It was woeful.
I cleaned the interior a couple days after that shot.
Lets talk Manual gear ratios
- Thread starter bradc
- Start date
haha.. Yeah I know. It was woeful.
I cleaned the interior a couple days after that shot.
naughtika
OzVR4 Stalker
I just remembered.. when I cruise down the highway when I do 100km/h my revs at around 2700rpm.. and 110km/h at around 2900rpm... would that mean anything?
SupremeMoFo
Leaving Skid Marks
... then you do a manual conversion.As for the auto owners, when your gearbox dies, us manual owners will come sailing past
Have to say, now I've got a manual..................... Fantastic !!!
I lived with a tipo for 4 years and loved that, great looking car etc but a manual box is really the cream on the cake feels much, much quicker, probably isn't but the experience is what it's all about.
I lived with a tipo for 4 years and loved that, great looking car etc but a manual box is really the cream on the cake feels much, much quicker, probably isn't but the experience is what it's all about.
SiliconAngel
1 AYC Bar
Malc I'm glad to hear that - there aren't many people who have had extensive experience with both.
A few points.
I have the car jar speedo kit for my Sil80 as i run a different box (r33) and the speedo drive is from the gearbox. Easy to make and install.
Brad, its cool thinking but here's a curly one for you. I have changed the final drive in my Skyline and Sil80 but the Skyline is what i'll be referring to here. It went from a final ratio of 4.3 to 4.11 Now this is a very small change and dropped revs at 100km/h from 3280 to 2900. I did this thinking that it would have to improve fuel economy as the engine was spinning slower for the same speed- less fuel etc etc WRONG!
Fuel economy actually got worse!. It went from around 10.2-10.4 km/L to 9.5 km/L......so the million doolar question is why. Well it's very simple.
Think of it in these terms. Compared to the standard gearing, the new taller gearing is actually harder for the engine to get going-( try getting a 10 speed racing pushbike going from stand-still in its smallest gear- piss easy, now use it's tallest gear- ken hard- yes i know this is an extreme difference in gear ratios, but even slight changes will have a dramtic effect on your engine) Also when going up hill the taller gearing actually uses more throttle to complete the same task, so, you are using more throttle for longer( not good for you fuel economy). Only on level ground will it maybe make a difference.
So i told you all that to say this, yes the idea is sound, however depending on the engines torque characteristics (remember its torque that gets you going) it may have a negative effect. It did on my car. Also to add weight argument. A mate did the same to his 5.7 litre V8 holden wagon. He dropped a SHORTER ratio diff in to get it off the line more easily for towing and guess what??? His fuel economy got better!!!
SO, what to take from this. Yes your engine may spin over a little faster with the standard gearing, but its doing it easily that with taller gearing and using less throttle to do the same job.
Manufacturers don't just throw random gear ratios at cars, it's always a compromise.
In finishing and i know this is a longish post, but generally companies offer different gear ratios for racing and in most part they are doing this to suit different tracks, fuel economy isn't in mind.
And yes ive swapped the final ratio in my skyline a few times and fuel economy always favours the shorter ratio!
Hope this adds food for thought.
I have the car jar speedo kit for my Sil80 as i run a different box (r33) and the speedo drive is from the gearbox. Easy to make and install.
Brad, its cool thinking but here's a curly one for you. I have changed the final drive in my Skyline and Sil80 but the Skyline is what i'll be referring to here. It went from a final ratio of 4.3 to 4.11 Now this is a very small change and dropped revs at 100km/h from 3280 to 2900. I did this thinking that it would have to improve fuel economy as the engine was spinning slower for the same speed- less fuel etc etc WRONG!
Fuel economy actually got worse!. It went from around 10.2-10.4 km/L to 9.5 km/L......so the million doolar question is why. Well it's very simple.
Think of it in these terms. Compared to the standard gearing, the new taller gearing is actually harder for the engine to get going-( try getting a 10 speed racing pushbike going from stand-still in its smallest gear- piss easy, now use it's tallest gear- ken hard- yes i know this is an extreme difference in gear ratios, but even slight changes will have a dramtic effect on your engine) Also when going up hill the taller gearing actually uses more throttle to complete the same task, so, you are using more throttle for longer( not good for you fuel economy). Only on level ground will it maybe make a difference.
So i told you all that to say this, yes the idea is sound, however depending on the engines torque characteristics (remember its torque that gets you going) it may have a negative effect. It did on my car. Also to add weight argument. A mate did the same to his 5.7 litre V8 holden wagon. He dropped a SHORTER ratio diff in to get it off the line more easily for towing and guess what??? His fuel economy got better!!!
SO, what to take from this. Yes your engine may spin over a little faster with the standard gearing, but its doing it easily that with taller gearing and using less throttle to do the same job.
Manufacturers don't just throw random gear ratios at cars, it's always a compromise.
In finishing and i know this is a longish post, but generally companies offer different gear ratios for racing and in most part they are doing this to suit different tracks, fuel economy isn't in mind.
And yes ive swapped the final ratio in my skyline a few times and fuel economy always favours the shorter ratio!
Hope this adds food for thought.
bradc
1 AYC Bar
- Thread starter
- #30
It depends on the type of driving you're doing I think. For long motorway cruises the auto's use less fuel than the manuals, which is exactly the opposite of most cars out there!
I do agree though that going too far off can cause problems, always needing more throttle and having less torque at the wheels in each gear is going to be the downside, but I still maintain that for people doing lots of highway miles, their fuel economy will improve, especially because in our case with the stock ecu and turbos, at 3000rpm you're only 1mm of throttle movement away from making boost, and then the afr and fuel economy goes to hell.
I do agree though that going too far off can cause problems, always needing more throttle and having less torque at the wheels in each gear is going to be the downside, but I still maintain that for people doing lots of highway miles, their fuel economy will improve, especially because in our case with the stock ecu and turbos, at 3000rpm you're only 1mm of throttle movement away from making boost, and then the afr and fuel economy goes to hell.
I disagree, i do lots of highway miles which is why i changed the diff to a taller one in the first place, my fuel economy is better with the shorter gearing.
Using taller gearing makes the engine work harder in every aspect, so fuel economy will always be worse than shorter gearing, UNLESS the engine is operating on or almost on it's peak torque.
I back that up with my mates V8, it changed the revs in 6th from 1600 to 2000 @ 100km/h and his fuel economy got better.
Also, if you go to a shorter gearing in the Legnum, you may find that you have more headroom before coming onto boost.
As an aside, one thing i'll be looking at shortly is rebuilding the engine with a higher compression ratio. I'll look at upping it from 8.5 standard to 9.0. Ive just done exactly that with a RB26/30 build. A friends 26/30 has heaps better response off-boost at 9.0 Also this would reduce the amount of boost required to run to achive X horsepower than with 8.5. This will also have a positive effect on fuel consumption as the engine will perform much better before reaching the swap over point from NA to boost.
Yes i know, what i was getting at was that even an engine with a lot of torque like the v8 did better with shorter gearing. As it was moving it toward it's peak torque which is around 3800ish which is a lot higher rpm than the old 5.0litre
As our engine develops peak at 3200, i reckon the gearing in 5th is pretty close to the mark, moving it lower and away from there will only make it worse.
As our engine develops peak at 3200, i reckon the gearing in 5th is pretty close to the mark, moving it lower and away from there will only make it worse.
mookers
puri puri
- Location
- Frankston, Melbourne, VIC
- First Name
- Derek
- Drive
- CL9 Accord Euro Lux, GE Jazz VTi, Evil Supervillain Chair, Homemade Portable Square Drumkit
I'm not sure this would be the case - judging from my newly audible turbo whine, you'd really be making boost only under accleration or other load. Steady state cruising, even at higher RPMs, will see the turbos quite relaxed. Unless there's something wrong with my car - but I can't see why the turbos would be boosting unless they were actually needed.
Someone correct me if I'm wrong?
G
Guest
Unregistered
Great post Brad! Can you please post the part numbers required for your preferred setup? I would be interested in costing out this change as I plan to do some regular long trips in the Leggy.
bradc
1 AYC Bar
- Thread starter
- #38
The 3.73 final is only available from www.teamrip.com
The 0.720 5th gear is MR581018 (output shaft) and MR581020 (input shaft) I was quoted $167 and $175 for the gears each from Ralliart who tend to give me good prices.
The 0.720 5th gear is MR581018 (output shaft) and MR581020 (input shaft) I was quoted $167 and $175 for the gears each from Ralliart who tend to give me good prices.
