I have a 92 3.0L petrol/gas NH Pajero auto
Engine has been swapped over recently and gas installed (done about 190k)
Running 31/10.5/R15
I went up to the Cuckoo restaurant (Dandenong way) a few weeks ago and really struggled to get up there. Spent a fair bit of time in 2ng gear doing 40-50kph. (where my mates prado would have no problem getting to 80kph)
It doesn't have the grunt that i would like it to.
Was wondering if I went down to 29" tyres would i get any improvements?
Ps:very little difference in power from gas to petrol and i run on petrol (instead of 40kph it could get 50kph)
All this said I dont push the car over the limit but I do like to work the engine as thats what its made for right? (going up the hill was at about 4000rpm 5000 at most)
cheers in advance.
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tyre downsize?
Moderators: toaddog, TWISTY, V8Patrol, Moderators
tyre downsize?
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92 NH Pajero 3.0L LPG
92 NH Pajero 3.0L LPG
Hi dmck,
It can be difficult to compare two separate vehicles from different maker with defferent weights, gearing, engine performance, tyre size and load and compare them as a package.
If you were concered with the paj lacking power after the engine swap/gas conversion i would start there.
If you ae considereing changing tyre size think of the performance change (with regard to force) with reduction in tyre size to increase. for example:
I have a car, it produces 200nm at the wheel. That means at 1m radius i will be producing 200n however, the tyre does not have a 1m radius a 31 inch will have more like 0.39m. Therefore if we divide our torque by 0.39 we get 512n which is the felt force at the outer circumference of the tyre.
but now i decrease my tyre size to 29 inches which is .36 and once again dividing the torque by that gives us 555n.
So, we have gone from 512n to 555n which is an 8.4% increase in force for a 6.9% decrease in tyre diameter. - this illistrative only.
Effectively, changing your tyre size just changes your gearing. going to a smaller diameter tyre may improve drivability but highway fuel consumption may suffer, your speedo accuracy will change and you could hinder off road performance.
In my opinion there is no substitute for cubic inches. If you want more power do exactly that
Hope that helps.
Cheers, Dave.
It can be difficult to compare two separate vehicles from different maker with defferent weights, gearing, engine performance, tyre size and load and compare them as a package.
If you were concered with the paj lacking power after the engine swap/gas conversion i would start there.
If you ae considereing changing tyre size think of the performance change (with regard to force) with reduction in tyre size to increase. for example:
I have a car, it produces 200nm at the wheel. That means at 1m radius i will be producing 200n however, the tyre does not have a 1m radius a 31 inch will have more like 0.39m. Therefore if we divide our torque by 0.39 we get 512n which is the felt force at the outer circumference of the tyre.
but now i decrease my tyre size to 29 inches which is .36 and once again dividing the torque by that gives us 555n.
So, we have gone from 512n to 555n which is an 8.4% increase in force for a 6.9% decrease in tyre diameter. - this illistrative only.
Effectively, changing your tyre size just changes your gearing. going to a smaller diameter tyre may improve drivability but highway fuel consumption may suffer, your speedo accuracy will change and you could hinder off road performance.
In my opinion there is no substitute for cubic inches. If you want more power do exactly that
Hope that helps.Cheers, Dave.
loose as a goose
not so much a problem with the car loosing power after gas more it never had it to start with.
im looking at upgrading to a 4.5L 80 series in the next 6 months but was looking at a cheap option for possibly getting up to the snow this season without having to push the car so hard (going up hill at low revs or in 2nd gear at very high).
I was looking at buying a cheap second hand set to just put on the car for these trips to the snow and then off loading them after keeping the 31" for any offroad play and when i sell her.
speedo doesnt worry me that much as i can just use the gps speed.
so overall? very little increase in power due to the gearing? not worth it or will a get some difference
im looking at upgrading to a 4.5L 80 series in the next 6 months but was looking at a cheap option for possibly getting up to the snow this season without having to push the car so hard (going up hill at low revs or in 2nd gear at very high).
I was looking at buying a cheap second hand set to just put on the car for these trips to the snow and then off loading them after keeping the 31" for any offroad play and when i sell her.
speedo doesnt worry me that much as i can just use the gps speed.
so overall? very little increase in power due to the gearing? not worth it or will a get some difference
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92 NH Pajero 3.0L LPG
92 NH Pajero 3.0L LPG
Dave's explanation is pretty good at indicating the sort of increase in driving force you'll get for changing the tyre size, and he's right that there's always a trade-off. In this instance, improved hill-climbing through increased revs will be offset by higher revs at highway speeds.
By mentioning 29" tyres, I presume you know the NH GLX came from the factory with 235/75R15 tyres, which are nominally 15". So it's not like you'll have the only Paj out there on 29s.
Have you given it a good tune? I had a car on a dyno a couple of times earlier this year. First was exactly as I'd been driving it, and I took it back again after changing plugs, leads & air filter and stepping through the Gregory's manual "tune" procedure (it's EFI) which was basically idle speed, TPS and ignition timing. From 2100 to 2700 rpm I picked up around 15Nm at the wheels (about 7% of total).
Make sure you ground the engine check connector when you set the timing on the Paj - do it wrong, and you'll have retarded ignition, which won't help your power either. Running on gas you should be able to use more ignition advance than standard, and running in cold air (i.e. snow country) will also allow more advance. A decent service & tune won't cost as much as new tyres, and some playing with your ignition timing won't take as long as swapping the wheels over. Do you have a lot to lose?
By mentioning 29" tyres, I presume you know the NH GLX came from the factory with 235/75R15 tyres, which are nominally 15". So it's not like you'll have the only Paj out there on 29s.
Have you given it a good tune? I had a car on a dyno a couple of times earlier this year. First was exactly as I'd been driving it, and I took it back again after changing plugs, leads & air filter and stepping through the Gregory's manual "tune" procedure (it's EFI) which was basically idle speed, TPS and ignition timing. From 2100 to 2700 rpm I picked up around 15Nm at the wheels (about 7% of total).
Make sure you ground the engine check connector when you set the timing on the Paj - do it wrong, and you'll have retarded ignition, which won't help your power either. Running on gas you should be able to use more ignition advance than standard, and running in cold air (i.e. snow country) will also allow more advance. A decent service & tune won't cost as much as new tyres, and some playing with your ignition timing won't take as long as swapping the wheels over. Do you have a lot to lose?
I have a GLS. The tyres on it are 31/10.5 /R15 and thats all ive seen on it. not sure what was standard for it.
I took it to a LPG place to get it dyno tuned and they said the LPG system was crap and needed to be replaced (its an old system... they wanted to change pretty much every lpg under the bonnet). when they mentioned 1500+ to sort it all out properly i ran... well they said the system is ok for what it is and will still go so not worth spending 1/3 of the cars value to get a slight improvement.
Also i cant really see how the gas system could be at fault as there is very little improvement in power on petrol.
Any recommended places to get a tune in melbourne and how much am i looking at? i might do leads sparks and filter first.
When i had the engine swapped over i had a new timing belt and harmonic balance in it. not sure it that means the timed it all for me or not though.
I had the engine swap as the bolt that is on the end of the cam shaft broke and was carving up the inside of the motor. Ive heard this happens every now and again. Word of advice MAke sure that bolt is tight and if you really like to dot your i's n cross your t's get a replacement bolt for about $50 online.
I took it to a LPG place to get it dyno tuned and they said the LPG system was crap and needed to be replaced (its an old system... they wanted to change pretty much every lpg under the bonnet). when they mentioned 1500+ to sort it all out properly i ran... well they said the system is ok for what it is and will still go so not worth spending 1/3 of the cars value to get a slight improvement.
Also i cant really see how the gas system could be at fault as there is very little improvement in power on petrol.
Any recommended places to get a tune in melbourne and how much am i looking at? i might do leads sparks and filter first.
When i had the engine swapped over i had a new timing belt and harmonic balance in it. not sure it that means the timed it all for me or not though.
I had the engine swap as the bolt that is on the end of the cam shaft broke and was carving up the inside of the motor. Ive heard this happens every now and again. Word of advice MAke sure that bolt is tight and if you really like to dot your i's n cross your t's get a replacement bolt for about $50 online.
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92 NH Pajero 3.0L LPG
92 NH Pajero 3.0L LPG
Ha ha mavericks come with a measley 215 80 16 ( 29.54"[!]) I'm running 36" pedes and top end power is only hindered by the windmill effect the tyres have at speed, I am ATM running 35" Big Horns and get the same top speed (when calculated) as 32" road terrains. I can still drive up a hill towing a car on a heavy car trailer, I just select the next gear down, simple. Tyre size is directly linked to gearing, it's the leverage force required to move the vehicle.
Don't take life too seriously...it isn't permanent.
What would the equivalent of 29" tyres be in the metric 265/65/15?
and mines a auto so its a bit of a fight between 2nd n 3rd gear some times...
3rd can be right down at 2000rpm and dropping and 3rd can be at 4000+
whit hte clasifieds down anyone have a good idea where i can get some cheapish tyre n rim packages...
only looking to hold onto them for 6months and then get rid of them....
that or anyone have a spare set and want to hire them out to me just for my trip up to the snow (if there is much difference noticed)...?
and mines a auto so its a bit of a fight between 2nd n 3rd gear some times...
3rd can be right down at 2000rpm and dropping and 3rd can be at 4000+
whit hte clasifieds down anyone have a good idea where i can get some cheapish tyre n rim packages...
only looking to hold onto them for 6months and then get rid of them....
that or anyone have a spare set and want to hire them out to me just for my trip up to the snow (if there is much difference noticed)...?
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92 NH Pajero 3.0L LPG
92 NH Pajero 3.0L LPG
anyone got any to swap/sell
http://www.outerlimits4x4.com/ftopic211720.php
got some 245/70/16 from a cruiser but looking for smaller still
http://www.outerlimits4x4.com/ftopic211720.php
got some 245/70/16 from a cruiser but looking for smaller still
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92 NH Pajero 3.0L LPG
92 NH Pajero 3.0L LPG
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