any way to change the gear ratios in manual?
 

i noticed that i have to hit 3k rpm in 6th gear to go 70 mph in my car, is there anyway to reduce the rpms? or gear's ratio? or does anyone have any idea how much it would cost?

thats weird when in 6th at 3k im going ^80s

do you have an auto? Mu manual is above 3k at 70.

Thr easiest way would be to install a taller final drive in the diff. But your car would suffer dramatically performance wise. What is so bad about being at 3k at 70 anyway? My s2k would sit about 4800 at 70. Are you concerned with noise, gas mileage?

I haven't seen a taller final drive offered yet, only shorter final drives.

you can put on larger diamater wheels and tires

and 3k at 70mph is nothing

my VW used to do 4k at that speed and still got better gas mileage.

yes gas mileage mainly. i love the sound/noise of the engine and it makes me feel like i have a powerful engine by revving it highly but since i've driven an auto, it would it 70mph at 2300rpm vs the manual at 3000 so....gas mileage suffers, usually 6th is cruising mode not revving mode.

A lexus 3.727 diff is available that will drop the rpm by about 10%
6th gear will still be lower than the AT.

http://www.ft86club.com/forums/showt...s+differential

You won't necessarily get better MPG with a taller ratio. Our engines make power higher along in the RPM band, putting your gearing ratio so that you're cruising at 2K RPM would make sense on a different engine, but on ours, you'd be putting more stress on the engine.

The Subaru and Toyota guys have put considerable thought into the design of the engine and its gearing. Unless you change HP output, I wouldn't really mess with gearing.

Lol top gear at 80 my Rpms are sitting at a cool 5100rpms

My dads LS does 80MPH at ~2000RPM. It has the torque to back that up though; we don't.

The auto uses significantly less fuel than the manual with its much higher top gear and the engine is quite happy at 2000rpm. I floored it at 2000rpm in top and it just quietly picked up with no complaints.
Having said that I was expecting the manual to feel undergeared but after breaking our 110kph max limit soon after changing into third and 3 gears still to go I changed my mind.
When I change the tyres I will likely stick with 17" and 45 profile for comfort but go to say 245. That will raise the gearing by 4.2% to make the speedo about spot on if it reads the same as most and knock the 110kph revs down from about 2950? to 2826.

Edit- Of course it will still read 2950rpm or whatever it is at 110kph but the car will still be going 4.6kph faster than it was.

This site says those tyres will fit on the original 7" rims but 235 might be safer?

http://www.rimsntires.com/specs.jsp

What?

My dad's LS460, equipped with an 8 speed automatic, spins at 2000RPM at 80mph. 4.6L V8 engine IIRC.

Desperate measures to reduce the fuel consumption of something so heavy and with the aerodynamics of a brick.

Oh absolutely. 25MPG cross-country highway on a recent trip. That's decent for an AWD V8. My point was it has the torque to back that up as well, we don't. Doesn't really matter because the trans will downshift to the proper gear anyway.

There's not such a huge difference in torque when you take the weight into account. The 86 has almost 70% of the Nm per kg of the Lexus and you can close that gap further as the speed rises and the aerodynamics come into play.
Granted the Lexus 'might' have a bigger % of its torque at 2000rpm but as you say, as soon as it needs torque it changes down to source it from higher rpm's, same as the 86.

Don't forget the auto 86 is ony pulling about 2,300rpm at 70mph and quite happy to cruise at that.

Brilliant fuel consumption on that trip!

I hate going off topic but just want to say, although it's a different car of the same concept, my E39 was about as aerodynamic as my BRZ (c.d. of .29 I think). And top gear at 3k rpms was at a brisk 107mph ;). I can assure you that thing handled highway cruising with good fuel consumption just fine.