7 replies to this topic

[bengreen55]

Hi what gear ratio are you using I have a 2009 k20z4 and it's reving to hight at 60/70mph just wondering what ratio is best and where I can get one from thanks

[Luigi33]

You have a 6 speed box right? Mine is standard gear ratio but will do 120mph + maybe more in upper gears. 1st and 2nd gear very short

[MRA]

So you guys might need the services of a gear cutter then.....

[bengreen55]

Team it got the standard honda 6 speed box It will probably do the same but when I am doing a bit of grandad driving it's reving to high at say 60mph I wondered if there was a ratio that would gear it up a bit just to lower the reves a little at cruising speed

[cptkirk]

Hi what gear ratio are you using I have a 2009 k20z4 and it's reving to hight at 60/70mph just wondering what ratio is best and where I can get one from thanks

 

Original FD in the K20A2 EDM EP3 is 4.764.

 

Here's the Honda part number for a 4.389 final drive kit: 23227-PNS-305 about £500 for OEM parts and a possible lead time of a few weeks.

 

I am using a 3.9FD hitting 60 in 2nd gear at the rev limiter, cruising at 70mph=approx 3400-3500rpm in 6th (from memory). It will do approx 150mph in 5th and god only knows what it'd do in 6th at the rev limiter. This all done on 225/45 R13 Toyo R888's

 

by the way, I haven't ordered or used the part number I've supplied but I believe it is a direct Honda replacement.

Edited by cptkirk, 26 February 2016 - 10:14 AM.

[bengreen55]

Thanks for that info mate is yours an aftermarket part if so could you point me in the right direction

[cptkirk]

the 3.9 is a Zcars supplied part, unsure if they are still able to get them though????

 

If I were to do this again I'd go for a 4.3 and then look to swap out the 6th for a nice tall gear, I think the TSX has a taller 6th??. You can find K20 gear ratios on the net and also gear ratio calculators that allow you to put in tyre size, gear ratios, FD and revs and it'll give you the speed achievable in each gear at the rev limiter.

 

Be warned that if Zcars get their FD from the same suppliers then the holes in the FD are 10mm not 11mm and you'll need to get them spark eroded to 11mm to make them work with an OEM or Quaife diff. An extra cost I did not foresee.

[KTM kid]

 

Hi what gear ratio are you using I have a 2009 k20z4 and it's reving to hight at 60/70mph just wondering what ratio is best and where I can get one from thanks

 

Original FD in the K20A2 EDM EP3 is 4.764.

 

Here's the Honda part number for a 4.389 final drive kit: 23227-PNS-305 about £500 for OEM parts and a possible lead time of a few weeks.

 

I am using a 3.9FD hitting 60 in 2nd gear at the rev limiter, cruising at 70mph=approx 3400-3500rpm in 6th (from memory). It will do approx 150mph in 5th and god only knows what it'd do in 6th at the rev limiter. This all done on 225/45 R13 Toyo R888's

 

by the way, I haven't ordered or used the part number I've supplied but I believe it is a direct Honda replacement.

 

WOW Cpt KIRK - busa engines have same problem, but its easy to just swap over front or back sprockets. think mine will do about 125mph from memory.