harvey

iTrader: (48)

http://bbs.22b.com/ubb/Forum23/HTML/000097.html

This was going on in October so the manufacturer (not supplier) had plenty of oportunity since that time to address the problems.

Where does this leave Richard Dowsett.

T-uk

Perhaps the dealer and 3rd party thread can be reopened for Dowser since although John has a promise of a refund on return of the kit, Dowser is not presently in this position.

Lone Ranger

I have been an observer on this board for some months now but do not have a lot of technical knowledge. I have no affiliation to anybody on this board but RVSR Racer has been kind enough to give me some pointers.

I think it is clear if you guys go back in time that Harvey has only spoken the truth and tried to be helpful in my opinion.

I had no idea that this thread from back in October even existed and personally think that if questions from three months ago still remain unanswered, in light of recent threads, then something is wrong.

I am currently in the process of modifying my STi 8 and would not have a problem considering further advice from Harvey, Andy F, John Banks etc... as these guys seem to know what they are talking about and have no commercial axe to grind. Thanks again to RSVR Racer.

Ron.

dowser

Harvey, it leaves me with a refund and the fun of fitting a much heavier 6MT

Richard

harvey

iTrader: (48)

Richard: I have resisted the 6MT so far because it means an extra gearchange on the 1/4 and the first four ratios are low and close but the gearshift is far quicker than my STi 5MT. Very interested in your assessment once you have run it and the novelty factor has worn off. Mail me off line if you want to go through it in detail.

P20SPD

iTrader: (1)

Surely with your bhp and talk you should surely be able to set off in second gear, thus keeping the gear changes to the same number as the 5MT?

harvey

iTrader: (48)

You forgotten your last e-mail already ? Spat your dummy out said you would never talk to me again and didn`t want to hear from me ever again.
Absolutely no point having a 6 speed box which is heavier than the 5MT if you are only going to use 5 gears, the first gear change would become a dog leg and the ratios are so close they do no justice to a 585 bhp 464 ft.lb engine.

P20SPD

iTrader: (1)

Thats me speaking...

David... On stevens laptop... please dont tell him gone to bed cant handle family life..

i was refering to 1/4 mile not 'proven' daily driving..

Ps.. you need some better excuses now nights are getting lighter.. I aint taken the crown yet, however the ball aint in your court

David

PS im still not running more than 12psi..

PS...psss having 'not ever' read stevens emails, he didnt spit his dummy out, he just wont lower himself to petty / pointless arguments.

The new year brought many new things.

Ill see you at the pod or elvington..

David (again... )

dowser

Harvey,

It'll be interesting to compare JDM vs UK 6MT ratio's for sure, the gap between 4th and 5th should disappear. At the cost of top speed, but my car is mainly for track work....should be perfect

Richard

john banks

On 215/40R17 tyres, with % increase for each gearchange, and revs that you drop back to after 7000 RPM and 8000 RPM changes

JDM speed per 1000 RPM:
1st: 5.0 mph
2nd: 7.6 mph (+52%), 4600, 5300
3rd: 10.3 mph (+36%), 5200, 5900
4th: 13.5 mph (+31%), 5300, 6100
5th: 17.1 mph (+27%), 5500, 6300
6th: 21.5 mph (+26%), 5600, 6400

UK 6MT speed per 1000 RPM:
1st: 5.0 mph
2nd: 7.6 mph (+52%), 4600, 5300
3rd: 10.3 mph (+36%), 5200, 5900
4th: 13.5 mph (+31%), 5300, 6100
5th: 18.7 mph (+39%), 5100, 5800
6th: 24.0 mph (+28%), 5500, 6200

UK 5MT speed per 1000 RPM:
1st: 5.2 mph
2nd: 9.3 mph (+78%), 3900, 4500
3rd: 13.3 mph (+43%), 4900, 5600
4th: 18.7 mph (+41%), 5000, 5700
5th: 24.6 mph (+32%), 5300, 6100

If I could make my 2.5 rev to 8000 RPM and make power there, my preference would be the UK 5MT, but it is too weak.

How about a JDM if you could lengthen all the gears?

[Edited by john banks - 1/17/2004 1:31:34 PM]

T-uk

I wish you would stop looking for peak power, as high up the rev range as possible. this does not make a balanced "drivers" car.

sure if all you want to do is produce the biggest peaks and straight-line drags, then fair enough but scoobs are supposed for work round the twisties.

IMO a redline is not to make power right up to , but to make a car feel flexible in a driving environment, preferably with plenty corners . this to me means, that you want to peak power about 1000rpm before the limiter, then the option is there to rev it out to the next corner or change.


[Edited by T-uk - 1/17/2004 2:42:18 PM]

john banks

At the moment though if I revved to 8000 it would make peak power 2500 RPM before the red line, and I would be changing up and landing AFTER peak power in every gearchange except 1-2! I can understand revving beyond peak power for flexibility, but there is no point in have 2500 RPM after it and never actually hitting the peak. Rev limiter should be lower or the breating better to get the 2.5 to make the power up to 8000. That is very expensive.

Agree the UK 6MT has a funny gap from 4th to 5th which is out of character with the rest of the box and spoils the rhythm. JDM with the UK 6th would be nicer. Possible?

T-uk

but that is the point john.

with your car with classic gearing, everything felt "spot-on" for your turbo and limiter.

now with the first 4 short gears and jump to 5th is feels strange. I really think subaru UK have made a right bawbag of the UK 6speed box trying to mix the short with tall gearing.they should have made an equal spacing between the gears.

[Edited by T-uk - 1/17/2004 3:05:09 PM]

T-uk

UK 6MT speed per 1000 RPM:
1st: 5.0 mph
2nd: 7.6 mph (+52%), 4600, 5300
3rd: 10.3 mph (+36%), 5200, 5900
4th: 13.5 mph (+31%), 5300, 6100
5th: 18.7 mph (+39%), 5100, 5800---bawsacked the gearbox here IMO
6th: 24.0 mph (+28%), 5500, 6200

harvey

iTrader: (48)

David : Not really sure what you are on about which is not unusual.
Richard : Very interested in your practical assessment when available.
John : 8K RPM on the 2.5 might be a bit risky even if it wants to breathe that far.

Pavlo

I would say either 6speed ratios are ideal for 7000rpm limit, especially with larger turbo like some of the 2.5 sti users wil be getting (pure guess).

I think John's smaller (than say harvey's) turbo is a little different as it makes a high proportion of peak power from 4500 through to 7000, making the UK 5mt a jst workable, longer 1st (like the lateral kit) probably helps the 1-2 dip though.

The problem is the diffs will not change the change points and drop back RPM (ie after change) just the road speed at that point.

Paul

The Fixer

Ron (Lone Ranger) not sure how I fitted in to this thread but never mind....

Conrad

T-uk

paul, it is not really the ratio to the limit I do not like. yes, on john's car the first 4gears feel very short and will be even more noticeable, once jb really opens it up in the mid-range by banging the boost back up.

what I do not like is the even spacing between the first 4 gears,then a jump to fifth with equal jump to top. it is worse coming down the box, if you are "heel--toeing", the drop to fourth throws the whole rhythm of the box out. you will get used to it but the issue on jb's car is it now feels like it needs a larger turbo and 8k limit for the first 4 gears, but feels right for the 20g with 7k limit at the moment in 5th and 6th. I am not sure if the 20g could flow enough in the lower gears to support an 8k limit but it feels a really poor mix and matched box IMO.

I would much prefer the equal JDM and build around that to suit the limiter of the engine. on a 2litre with a smaller turbo(TD05FE/MD304)with a 7k limit, the JDM box IMO will be great as a "drivers" car,not ideal for 1/4's though. throw on a bigger turbo though and I think a 8k limiter is required. this keeps the car flexible through the bends with a big turbo.

unfortunately, this is what jb had done. he had built around the classic 5speed ratios,using possibly the smallest turbo on the 2.5 to reach his goal and his car felt spot on, for a bit of everything. long enough gearing for a 1/4mile with enough torque to pull cleanly out the corners. although according to delta dash, the car had peaked well before the 7k limit it felt totally balanced for sprinted driving.

when I first tried john's box I though he had made a bad choice due to the mix and match UK gearing. however,when I found out that with a JDM on 215/40r17 tyres, with a 7k limit, it only equalled 150mph in top, I understood his compromise for his 450/400 target. I just think subaru uk should have made a proper box, rather than mix short with tall

john banks

This is what you would get with a JDM box if you could somehow make the front diff a 3.54 to match the rear without the 1.1:1 step, with max speed at 8000 RPM:

1st: 5.5 mph (44)
2nd: 8.4 mph (67)
3rd: 11.3 mph (90)
4th: 14.9 mph (119)
5th: 18.8 mph (150)
6th: 23.7 mph (190)

I'm probably dreaming, but this with an 8000 RPM limit of a torquey motor that breathed would IMHO be best of all. However, you'd still have four gearchanges to do that quarter.

john banks

Yesterday, with over 150 miles of driving and running at low boost I tried a few different types of roads.

On fast cruise it felt too short (for refinement) in 6th gear although it was always waiting around peak torque so that a flex of your toes was license threatening. This though is very similar to the old 5 speed.

On twistier roads, I would never use first anyway, and I found that if I just used one gear higher than I did with the 5MT it was OK. I never used 2nd, just 3rd, 4th, 5th, 6th, mainly 4th and 5th. There is a drop between them, but when you are driving along and never dropping the speed much then you could just be driving a 5MT, except the 4th to 5th is across the gate unlike the 3rd to 4th on the 5MT.

David_Wallis

Harvey..

David : Not really sure what you are on about which is not unusual.

I know what you mean, alot of people say that!

Jolly Green Monster

iTrader: (4)

It's not unusual... to dance with anyone.. dar dadda darr da..

Wow look at that Harvey wanted an argument and it has all gone serious 6speed talk

JGM

Edit due to me typing with 10 thumbs..

[Edited by Jolly Green Monster - 1/18/2004 9:14:43 PM]

Bob Rawle

Its my impression that the JDM version box is almost ideal, nice equally spaced ratios BUT, you do need the higher rpm limit especially in the lower gears, the UK box is a bit "spoiled" by the wider spacing, having already declared an intention to have a 2.5 with a 8000 rpm limit it was not an idle wish.
Peak power is about the maps and the breathing, if JB is using UK cams then 6400 is where it should be, with STi cams its possible to lift to 6800 which then "needs" the higher rpm limit.

Biggest problem is egt's which John has already highlighted however I am seeing up to 960 in the collector (ouch) but the pistons and clearances are good for it. Larger engine/turbo/breathing system = harder working = higher egt's ... inevitable as they say.

cheers

bob (great feedback JB)

johnfelstead

I produced this gear ratio, engine power, shift point graph recently which gives you a good ilustration of how you can work out what is the best rev range to use and what are the ideal shift points for maximun acceleration.

A lot of people think you should shift at peak power, this is wrong as doing that doesnt maximise the largest area under the power curve.

The first diagram shows shifting at the ideal point, past the peak power point.



The second diagram shows the effect of shifting at the peak power point, you can see how the amount of power used is less in total.



It's very easy to produce this type of diagram for your car, especially if you have Delta Dash to generate your gear ratio chart and you can use road dyno to generate your power curve if you dont have a rolling road plot.

You can also use this method to produce an engine flexibility chart by using the torque curve, so if you are after a lazy drive but with bags of torque, just do the same and generate your shift points for that type of driving.

SiHethers

Another option with deltadash is to plot speed on x-axis against vehicle acceleration on the y-axis. If you then overlay each gear you can see at which speed each gearchange should be to attain max acceleration, then work back to the rpm.



Simon

Andy.F

I know where you are coming from JF and I agree.....sort of
It's not however_quite_as simple as the examples you posted !

As each gear not only has a different efficiency but the engine acceleration rate in the higher gears is less than in the lower gears, this means that the time spent in each area of the power curve varies by gear.
eg if you use your 1st graph and shift points as an example, when you go from 4th to 5th, if you shift at the equal power x-over point you will increase the time you spend at the lower end of the curve due to the acceleration in 5th being slower.
Ideally you want to equalise the TIME spent at each bhp output in order to maximise the average bhp used. It may be appropriate to go past the point of equal bhp available in the next gear in order to minimise the time at the lower rpm in the higher gear.
This is why gears are closer stacked as they get higher eg drop in point is low from 1-2 but because the car picks up so quickly in 2 then it is a very small time span at lower power and as such has minimal effect on acceleration.
By far the best way to work out your optimum shift points for your own car (as they are all different) is to use a G force meter such as an AP22. Reading the G force graph, if you pull lower G when shifting up a gear then you shifted too early, if it is higher, you shifted too late.

You could also use a complex mathematical method to calculate optimum shift points but this would also need to account for wind resistance, rolling drag and the consequent mph drop during a gearshift.

Andy