2 vs 2.5 - VVT notable differences?
Discussion
Im looking for an NB car and as far as I can tell, both the mk2 and mk2.5 are pretty similar, aside from the latter having VVT and some 'aggressive' lines near the headlights.
Is this difference a cause for further investigation, or should i just not worry about it? I plan to improve the engine breathing a bit, but have no serious mods in mind.
My first thought is a difference in mpg, is there much in it?
Just trying to understand all the variable before i buy something that i will regret later on.
Is this difference a cause for further investigation, or should i just not worry about it? I plan to improve the engine breathing a bit, but have no serious mods in mind.
My first thought is a difference in mpg, is there much in it?
Just trying to understand all the variable before i buy something that i will regret later on.
I have a 2.5 and I drove my brother in laws mk2.
Mine felt more willing in the mid range. Theres no noticeable kick IMO for the VVT, just the acceleration feels more linear in the mk2. I drove on the motorway with him ahead, and there were a couple of occasions where he dropped down a cog and I did the same and 'gave chase' - mine seemed to reel him in slowly. I have read that the mk2.5 is a bulletproof engine due to several reinforced areas, wheras I have read there have been some bottom end failures in the Mk2.
That said, Internet opinion seems to be that the mk2 RS import feels faster than the uk VVT. I would like to try one for comparison.
Mine felt more willing in the mid range. Theres no noticeable kick IMO for the VVT, just the acceleration feels more linear in the mk2. I drove on the motorway with him ahead, and there were a couple of occasions where he dropped down a cog and I did the same and 'gave chase' - mine seemed to reel him in slowly. I have read that the mk2.5 is a bulletproof engine due to several reinforced areas, wheras I have read there have been some bottom end failures in the Mk2.
That said, Internet opinion seems to be that the mk2 RS import feels faster than the uk VVT. I would like to try one for comparison.
Mk2 RS has some trick cams and a higher compression ratio IRC, it's a genuine 160bhp.
The MK2.5 motor is give or take a few the same peak output as the MK2 engine, but it's area under the curve is much fatter. Mazdas VVT is just variable cam timing on the inlet, doesn't really do anything for peak power like Honda's VTEC system, which alters both cam timing and valve lift.
The MK2.5 engine has a 0.5point higher compression ratio, a better flowing intake manifold, and a MBSP which helps reduce crank flex at higher RPMs
Personally I think it's worth having, however if it's the choice of a tatty mk2.5 or a tidy mk2, it's not worth it that much.
Other minor changes between the two are adjustable headlight levels, amber interior lighting, different rear light clusters, altered exhaust manifold and cat, seats, centre console is massively improved over the MK2, they also have those clamp things for kids seats, and a proper OBDII port.
Oh and if you plan on modifying the ECU connector is completely different to the MK1/2 version, it's also a bugger to source to make a harness with.
The MK2.5 motor is give or take a few the same peak output as the MK2 engine, but it's area under the curve is much fatter. Mazdas VVT is just variable cam timing on the inlet, doesn't really do anything for peak power like Honda's VTEC system, which alters both cam timing and valve lift.
The MK2.5 engine has a 0.5point higher compression ratio, a better flowing intake manifold, and a MBSP which helps reduce crank flex at higher RPMs
Personally I think it's worth having, however if it's the choice of a tatty mk2.5 or a tidy mk2, it's not worth it that much.
Other minor changes between the two are adjustable headlight levels, amber interior lighting, different rear light clusters, altered exhaust manifold and cat, seats, centre console is massively improved over the MK2, they also have those clamp things for kids seats, and a proper OBDII port.
Oh and if you plan on modifying the ECU connector is completely different to the MK1/2 version, it's also a bugger to source to make a harness with.
The 160hp is a bit of a fallacy from what I have read, still rated at 140 like the UK cars from what I can see. A supposedly lightened flywheel, mildly hotter cams and a close ratio 6 speed box as well contribute to the sensation of being faster in gear. Top speed limited to 112 like all Jap stuff. At a Nutz dyno day a lot of naturally aspirated Mk2 's went on a dyno that has a reputation for accuracy. My standard 146hp made 128 (disappointed) at the fly with what I later found to be a slightly sticking rear caliper. The winning mk2 was a mk2 RS with 131 or thereabouts. Pretty sure that had an induction kit as well.
There was a mk2.5 RS with the VVT optimised for power and not emissions like UK cars which did make close to 160hp though. Not many of those about over here.
There was a mk2.5 RS with the VVT optimised for power and not emissions like UK cars which did make close to 160hp though. Not many of those about over here.
GC8 said:
Most NB2/Mk2.5s are rated at only a few PS more than the NB and the variable timing is more to do with emissions than performance.
The VVT is little to do with emissions, (at idle and fast idle the cam is in full retard - same as at high rpm - in the midrange it advances to full advance that's where it earns it's keep), It's mainly to do with area under the curve. Mid range torque is dramatically better compared to the MK2 engine.You can't really tweak it for top end either, full retard is where it makes the best power, if you start advancing the cam power drops off and you can't retard it any more than it is. To make more power you'll either need a different VVT cam and/or supporting mods.
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