gearbox ratio's

is there any difference in the gear ratio's of these 2 gearboxes
land rover 90 td diesel gearbox - land rover 90 2.5 petrol

reason i ask is i am struggling to get past 60 in my ninty which to me seems under powered and a mate says he can get 70 outta his.
both 90's have 200tdi disco conversions with disco transfer boxs, the only difference that i can figure is the gearboxes.
is there a difference in the ratio's or do i need to look as where as to why i'm low on power. i know its not a sports car but it does seem under powered to me.
hopefully someone can help me with this thanks in advance.

the same box 50a lt77 ,are you sure yours is 1.222 transfer box

this is the sticker on the side of my transfer box so i presume so mate

its not conclusive as could have had high gears changed ,diffs ratio 3,54 or changed ?

well with all the crud and sh*t on it and no signs of it being taken apart, i would say it has'nt had anything changed since factory and i bought the whole vehicle from a mate who knew the history of the vehicle. so i will double check with him about the transfer box. but i guess my next point of checking is inj pump timing and go from there.

probably not but diffs and t/box are only place ratios would be different from your mates ,does it feel like it runs out of power or gearing

it just seems to be revving alot for the speed its putting out. now my first landy was a 300 tdi disco and my mate said its just me cause i'm used to the speed of the disco and am not allowing for the fact that a 90 is geared lower than my old disco was.

it isnt really theres very little difference between disco and defender gear boxes diffs are the same as std ,it is all done in transfer box ,and sometimes diffs are changed to allow for big tyres on defender as 1.222 box and large rolling radius can be too much

By the time you hit 50 and onwards your speedo is as much use as toffee, i could do 85 in my old 19J and the speedo was smooth all the way up...until i checked and was actually doing 55.....

ok so would my tyre size make that much of a difference cause i'm running 235/85/16 mt (insa turbo's) atm and my mate is on 7.50 16 avon range masters

235 85's and 7.50's are the same dia....a tad more drag cause you're a bit wider and on muds but not enough to make the sort of difference you're talking about

right ok i will take it to the motor way with my sat nav connected then and try and get a true-?er reading than the speedo is telling me and go from there then. other than that the bugger is running sweet so might be best to leave well enough alone before i give it a complex and make it break down again lol

thanks for the help james and co. much appreciated

Do a search on changes to the injector pump on this site - I think its title is "sluggish disco" and it tells you how to make some simple changes to your injector pump. I did this on mine which was a 200tdi converted from 2.5 petrol and its transformed it.

If you want to meet up, I am only in Cheltenham - you could have a test and see what the difference is

you interested in coming down to salisbury plains on saturday could compare vehicles then as well as get some green laning in