V6 mk2 rpm range for motorway driving

[mr2-k]

Just wondering if anyone with a mk2 conversion could give an idea as to what sort of rev range they get doing 70/80mph?

I know on my n/a I can cruise easy at 3000-3500rpm doing 70, heard it was quite high on these V6's.

[AlunJ]

If you get 70mph at 3500 rpm on your current engine it'd still be 70 @ 3500rpm on the V6. To lower the RPM's needed for a given speed you'd have to use either a different gearbox, longer gear ratios / final drive, or really large diameter wheels :)

[Paul Woods]

ah yes aluns correct,this is down to the gearbox ratios....ie the 3s-ge revs a lot higher than the v6 so it doesnt seem as laboured at 3.5k rpm.

if you turn the gearbox input shaft at 3k rpm,its going to have the same road speed regardless of what engine provides that 3k rpm.

The thing that people notice with the v6 is because it redlines at 6.5k rpm it feels more "laboured" at 3.5k rpm than a 3s-ge does at motorway speeds.

On the manual v6 camrys in the US the gears are longer to counter this,but you lose bottom end pull...personally id rather have them the way they are and put up with the motorway anomally.

The solution for me would be to just swap the 5th gear cogs,ive heard the st165 set will work and provides longer legs in fifth but i dont know for sure.

[foxy-stoat]

my n/a box is at 4,000 at 70mph, so maybe turbo running gear is the way forward.

i have a mate who builds gearboxes, gonna ask him if it is just a case of pulling 5th gear out and slipping in a different one.

[OlberJ]

That's what i'll be doing, new 5th gear with the n/a box. Think i'll go with the celica box or longer, 5th gear should be used for top speed and motorway cruising.

4 gears is plenty for the twisties.

[foxy-stoat]

yup !!

its not as if i do much 100 + mph driving, just nice to have the revs down a bit at 70 - 100

i did do a hard launch the other day ( just to see how well it would launch )and the n/a clutch just slipped...so thinking the turbo set up would be better if your planning on doing a lot of 1/4 mile rips and stuff.

but once your off the line, the n/a clutch is fine.

[Garbe]

wayne did you have a new clutch installed?

[Fizzy]

There are some differences between the na and turbo gearboxes as well as revisions. On mine (rev 3 turbo box) I am doing 80 at 4k rpm in 5th. 70 is around 3k+..

Was thinking about changing the 5th gear, or possibly the final drive the lengthen the gears a bit. As was said earlier though, this would mess up lower gear acceleration a bit. Also mean I would need to get somebody to get the engine out/gearbox off, rebuild it etc. I'll leave as is for now, but may think about it in the future if I ever need to do any gearbox work. :D

[foxy-stoat]

wayne did you have a new clutch installed?

yup, was a new clutch

[Garbe]

I think due to costs changing the 5 gear would be pointless unless you do tons of motorway driving.
Mr2 V6 conversions are done for the pure fun/pleasure of the grunt provided by the V6.
If you change the final drive, as has been said it would affect the drive in other gears, which kind of defeats the object of the swap.

most peeps will probably only be on a motorway for maybe 5% of the time IF so much.
Unless we (i mean paul et al) can come up with a cheap solution it just does not seem like a worthwhile exercise for the little gain to be had.

(that is unless you are after top speed in which case you should be driving a supra)

[foxy-stoat]

thats why i was gonna pick up another box and have the 5th gear swopped, if it poo's up the whole drive, i'd swop it back.

would it change the rest of the gearing ratios if you just changed 5th...? have to admit, i know jack about gearbox ratios !!!

[OlberJ]

Think, at least this is in what i know about previous cars, it's fairly easy to remove and replace 5th gear with the engine and box still in car.

Just remove the end plate, pull off the old gear and then put on your new one. Don't know if this applies to Mr2's tho.

This way it's fairly cheap to do (cost of a 2nd hand st165 box?) and could be done as and when needed. If so i'd keep the original 5th gear and swap it at a track day then swap back to drive home.

[foxy-stoat]

i bet it aint that simple and cheap...NOTHING on these cars is.......apart from the V6 swop !! ;) PAULS THE MAN !!!

if it is as simple and cheap as to whip the cover off and swop the end gears over, it would be ideal !

[OlberJ]

As i say, that's the way it's been on previous cars but who knows when it comes to Toyota.

Gearboxes seem to look the same idea though. Not sure if there's room to get at it though.

[Paul Woods]

PAULS THE MAN !!!


well i was last time i looked ,hopefully its still there!

[mr2-k]

ah yes aluns correct,this is down to the gearbox ratios....ie the 3s-ge revs a lot higher than the v6 so it doesnt seem as laboured at 3.5k rpm.

if you turn the gearbox input shaft at 3k rpm,its going to have the same road speed regardless of what engine provides that 3k rpm.

The thing that people notice with the v6 is because it redlines at 6.5k rpm it feels more "laboured" at 3.5k rpm than a 3s-ge does at motorway speeds.

Would this be the same regardless of the flywheel chosen? i.e current one modified or alloy fidanza or one from the USofA?

I know different setups for flywheel are availible, would these make a difference?

:confused:

[OlberJ]

No, the gear ratios, and the final drive ratio (and the wheel/tyre size) are the only things that will change the revs at a set speed.

[mr2-k]

No, the gear ratios, and the final drive ratio (and the wheel/tyre size) are the only things that will change the revs at a set speed.

:popcorn:

Cheers

[burner]

well changing the rims for huge ones would lower the rpm but would also decrease the 0-60 times.. I'd like to go for some 13" wide boys but they would just look silly sitting well below the arches.. any ideas on the perfect rims?