POWER!

Hi, recently bought a cheap little Jimny. 1.3 Petrol 2001 88k
Ive not touched the engine apart from new plugs and ive got 2" suspension spacers on and bigger tyres (265/70/15) but im seriously struggling for top end power.
During off road and bottom end is fine but slight incline in the road and im fighting to keep it above 45mph! Motorway is an absoloute no go area for the little Jimny.
Never owned a Jimny but im just curious as to is it a common occurance or is it something i can fix?
Thanks.

Have you checked the air filter?

I have. even took the air filter out for a quick test and its the same.

Just noticed the tyre size.

If you're still on standard transferbox and ratio that's probably the cause of it.

Pretty massive tyres, which I'm guessing are remoulds.

still standard as far as i know, not too sure if the tyres are remoulded but i bought them a couple of weeks ago for £60 so couldnt refuse them. Any reccomendations on a different box or what i could do to mine?

Those tires are just tooooooo wide for Jim.

had standard little road tyres on with no tread when i got it. got offered the tyres off a friend who had no use for them anymore. so they are just a temporary fix until i sort some decent ones out. What tyres would be best reccomended for the 15s?

Have a read they are very large without changing the gearing

www.bigjimny.com/mediawiki/index.php?tit...age_-_best_practices

The rolling circumference of a standard Jimny tyre 205/70 x 15 is 2040mm, your running 265/70 x 15 at 2297mm per rotation.

Every time the wheel turns, you travel 257mm further than a standard car, a difference of over 10%.

So your gearing needs to be reduced by 10% to get back to normal performance, but.... that won't be a "normal" load on the engine and performance will still suffer.

You need to make a compromise to best suit your needs, big tyres look cool but cost in many ways, loss of performance due to gearing, a huge increase in unsprung mass ( the weight of the axle and tyres) and a massive change in friction.

If you've got a road car that you play with at weekends, keep two sets of tyres and change them when you play.

I run 215/70 x 15 which is only 57mm bigger than standard, it still gives a noticeable difference in gearing and I use third gear much more than I did.

sniper

DanRigg94 wrote: still standard as far as i know, not too sure if the tyres are remoulded but i bought them a couple of weeks ago for £60 so couldnt refuse them. Any reccomendations on a different box or what i could do to mine?

Can you tell us the size please because I wouldn't necessarily blame them - Jimny can be a little underpowered compared to mainstream motors.

I'm in full agreement with sniper. 265 tires will definitely have a negative effect on engine performance! I'm running BFG KO2 AT 215/75/15's on my Jimny which, in my opinion, don't compromise too much on engine performance while still giving the car more girth and beefiness for that rugged off road look!

Just had a look at the link Daniel provided and some of my numbers disagree, they are taken from errolstyres.co.nz, a source I've used for years and I am confident in their info. having modelled gearing on it in the past, successfully.

Please confirm numbers yourself.

sniper