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Optimum shift points for 2.2 I-CTDI acceleration

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babak

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Sofia
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2008 Accord I-CTDI
If I was after maximum acceleration what would my optimal shift points be on the 2.2 diesel?

Should i be shifting right around redline at 4.5k RPM or should I do it lower because the max torque and max hp is lower down on the diesel engine?

I am using the Premier EGR delete stage 1 map.
 
Stevan its all about your driving habits TBO so drive your car and experiment is my addvice.
Something to consider driving to the red line all the time is not good for any car :rolleyes: :rolleyes:
 
You can push it a little bit more, especially in first and second mate, to the point it cuts off the fuel. Its Honda, it will take it without a problem up to and beyond the red line. As a remapped car it should be driven like one! Make use of these horses, oh yeah!
 
Only change gear once you hit the rev limiter :lol: .

But seriously I shift up as low as possible. So as long as there will be enough torque in the engine to pull the car with slight acceleration then I'm happy. This gets you the best fuel consumption and least wear on your car. Then just spank the high revs occasionally to open the engine up and keep it breathing.

Mind you, the petrol I drive is rather different I suppose. But shifting up lower in the revs should make your fuel go further.
 
I've also S1 from elite so we have same maps so max torque is at around 2600 rev so if you want accelerate quickly then shift gears at this level, otherwise it's up to you when you'd change gears. ;)
 
Its no point redlining a diesel, shift when you feel the power fall off 3.5k would be it I reckon. Maybe Fahad can post a S1 dyno printout.
Plus diesels dont like having the b*****s reved off them.
 
There are dyno plots in the Premier Tuning section. From memory around 3800RPM would be an optimal shift point.
 
from 2.6k torque is falling down, from 3.8k bhp is falling down, at least in my car ;)
 
brodziu said:
I've also S1 from elite so we have same maps so max torque is at around 2600 rev so if you want accelerate quickly then shift gears at this level, otherwise it's up to you when you'd change gears. ;)
Click to expand...

brodziu said:
from 2.6k torque is falling down,, at least in my car ;)
Click to expand...

Exactly, so if peak torque is at 2600 you want that to be the exact midpoint between the revs in current gear and the revs in the next gear for the particular speed.

So to simplify, say you have peak torque at 2500, if you shift from 2nd to 3rd at 3500, the revs will drop down to 1500 - so that magical 2500 figure is directly in the middle, meaning you are getting the MAX out of the area under the curve between 1500 and 3500.
If you shift at 2500 and the revs drop to 800, then you're at a very low point on the curve and result in 'wasting' all those high torque values that come between 2500 and 3500.

Make sense?
 
And that was kinda the point, don't look at dyno plots - look at on the road testing, it all relates to health of the car, conditions at the time, driver skill and momentum at the time of acceleration. I wouldn't red line it but certainly there is still power towards the 4k marker and enough momentum to keep it in the torque zone when shifting gears.

To be honest, you don't want to be driving your car like this all the time, these cars are not made for straight line hammering on a regular basis.
 
Thanks guys. Of course I dont drive my car like this all the time ... lets say im doing it in the quest for knowledge.

HuskyMan said:
Exactly, so if peak torque is at 2600 you want that to be the exact midpoint between the revs in current gear and the revs in the next gear for the particular speed.

So to simplify, say you have peak torque at 2500, if you shift from 2nd to 3rd at 3500, the revs will drop down to 1500 - so that magical 2500 figure is directly in the middle, meaning you are getting the MAX out of the area under the curve between 1500 and 3500.
If you shift at 2500 and the revs drop to 800, then you're at a very low point on the curve and result in 'wasting' all those high torque values that come between 2500 and 3500.

Make sense?
Click to expand...

Makes sense but I think its overly simplified. This would be the case if the gear ratios didn't have to be taken into account but AFAIK because of multiplication from gear ratios a lower gear will have more torque than a higher gear regardless that it has fallen off of the maximum torque RPM because of the multiplication factor.

I think it might help if someone knows the gear ratios for the 2.2 - im specifically interested in the 6 spd. facelift.
 
I've got a 6speed 2.2ictdi Running the stock map and I feel that shifting at 4k seems to give optimal acceleration
 
4.5k rpm on my accord would be literally the last thing I would like to do :lol: a bit of a relaxed driver here.
 
babak said:
I think it might help if someone knows the gear ratios for the 2.2 - im specifically interested in the 6 spd. facelift.
Click to expand...

Saloon
5 Speed
Gear ratio
1st 3.933
2nd 2.037
3rd 1.250
4th 0.883
5th 0.687
Reverse 4.008
Final reduction Type Single helical gear
Gear ratio 3.285


6 speed
Gear ratio
1st 3.933
2nd 2.037
3rd 1.314
4th 0.975
5th 0.777
6th 0.653
Reverse 4.008
Final reduction Type Single helical gear
Gear ratio 3.785
 
Where does the Diesel redline? Is it around the 4K area?
 
I put together some numbers and calculations based on Salim's gear ratios for the 6spd.

First thing I did was take the dyno plot for the Stage 1 remap and map out the flywheel torque in 100 rpm increments. I couldnt find a stage 1 egr off dyno plot so I figured this was close enough.

Next step was calculation transmission torque based on the gear ratios.

I then added a table to the side which shows the RPM drop that happens when you shift gears so you know where you end up.

Ive marked the optimum shift points which I got in green but would love if anyone has any input if what ive done is correct. I think it makes sense.

POU9h.png


If anyone is interested I can send the excel file I used. Im not sure how to attach it here.
 
From your figures I would lower your shift points.
For example change 1-2 at 3900-4000rpm and your torque will stay at 190 and still be climbing instead of dropping to 140
 
Wow! That's hectic. Fancy doing one for the 2.4 Petrol ;) . No idea what the gear ratios are mind you :unsure:
 
So you're optimum shift points are between 3400 - 4400 RPM? LOL I'm sure I said 3800RPM ;) so my guess wasn't far off.
 
dont suppose you fancy plugging the numbers in for us poor sods who only have 5 gears ;)
 
Sam, you would just need to alter the gear ratios and delete the extra columns.

Interesting reading. Not far off my habits - when in zaust clearing mode ;)
 
Babak, if you email me (details in my profile). I will host the excel file for forum downloading.
 
Dan, its easy enough to do (my job involves building data reporting suites in access and excel), but I figured it would be faster and easier just to get the pic posted up for all to see. But if you can get the file hosted for all then everyone can alter the figures depending on their gearing and torque figures.:)
 
:lol: I love Excel and Access. If only the rest of Microsoft's departments could do as well as them (and the Visio team as well come to think of it).

Just wish I could get my head around VLOOKUP.
 
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