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Old 23rd July 2018, 21:38   #11
DMGRS
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Where did you see that Mat? The camshaft timing is certainly different on the 190 but there’s no mention of lift in RAVE.

Simon
I've seen it in tuning circles over the years - also the part numbers are different. I'll try and dig something out for you.
I could be wrong, and thinking of the advance we all know they have!
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Old 23rd July 2018, 22:17   #12
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Simon, I believe the following to be the actual press release by MG Rover when the MG ZT 190 was launched:

"The ZT range has newly-enhanced versions of MG Rover's all-alloy quad-cam V6 engine. For the ZT 190 models, several special features have been engineered to achieve the higher power output of 190Ps or 140kW, and increased torque of 245Nm.
Beginning with the variable length induction system, the air intakes have a 15% larger duct and a new intake diffuser. This provides a smoother airflow with less than half the usual pressure drop; it has also been tuned for a more sporting induction sound. Internally, there is a new inlet valve cam profile, advancing the inlet valve opening by 4°, as well as improved inlet porting.
To withstand higher cylinder pressures, the gudgeon pins and big end bearings have been upgraded, and the oil specification has been raised to ACEA-A3 for protection at sustained high revs.
A further contribution to performance comes from a new exhaust system, with 60mm diameter pipes in place of 57mm, new low-restriction metal-based starter and main catalysts and a modified rear silencer unit. This has larger-bore internal pipes, twin straight tail pipes and a mechanical valve that responds to exhaust pressure at around 4500rpm to by-pass the internal baffles.
This reduced back pressure helps create an attractive sporting note while still meeting all legal requirements for drive-by noise.
A redesign of the engine ECU software and specially designed MG throttle cams provide the right sporting feeling of responsiveness to the accelerator pedal, with a deliberate reduction of the normal throttle on/off damping.
Finally, an enhanced cooling system, with 20% greater cooling intake area, uses an improved-flow radiator and top hose configurations, with a new plate-type oil/water oil cooler replacing the oil/air heat exchanger"

The only difference with the inlet cams may be the 4 degrees of advance, but other apparently knowledgeable sources have said that the 190 and ZT 180 (not the ZS 180) exhaust cams have 8.8mm of lift and 244 degrees duration as against 8.2mm lift and 236 degrees duration on all other ZT and 75 engines. A check of the Rimmers catalogue shows that the part number for both inlet and exhaust cams is different for the ZT 190/180 engines to the ones on all other KV6's. I don't profess any technical qualification or knowledge on these matters - just an interested amateur.
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Old 23rd July 2018, 22:24   #13
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Where did you see that Mat? The camshaft timing is certainly different on the 190 but there’s no mention of lift in RAVE.

Simon
A discussion on it HERE Simon. I cannot vouch for any accuracy of it though.

............... and more on this forum
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Old 24th July 2018, 06:32   #14
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Originally Posted by minimutly View Post
Yep, cam timing specs are in there, both cams are different.
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I've seen it in tuning circles over the years - also the part numbers are different.
RAVE says that the 190 cam provides different valve timing. That’s not the same as increased lift. There is no mention of lift. What you’ve seen in tuning circles Mat appears to be uninformed gossip.
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... other apparently knowledgeable sources have said that the 190 and ZT 180 ... exhaust cams have 8.8mm of lift and 244 degrees duration as against 8.2mm lift and 236 degrees duration on all other ZT and 75 engines.
Well Crispin, don’t you think these “apparently knowledgeable sources” should declare from where they got their information? If it’s true, then why isn’t it in the comprehensive press release which you’ve quoted?
Mat; if you have both camshafts in stock could you measure it for us please?
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A check of the Rimmers catalogue shows that the part number for both inlet and exhaust cams is different for the ZT 190/180 engines to the ones on all other KV6's.
No-one can conclude that the 190 camshaft has increased lift simply because it has a different part number.

Simon
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Old 24th July 2018, 15:14   #15
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RAVE says that the 190 cam provides different valve timing. That’s not the same as increased lift. There is no mention of lift. What you’ve seen in tuning circles Mat appears to be uninformed gossip.

Well Crispin, don’t you think these “apparently knowledgeable sources” should declare from where they got their information? If it’s true, then why isn’t it in the comprehensive press release which you’ve quoted?
Mat; if you have both camshafts in stock could you measure it for us please?

No-one can conclude that the 190 camshaft has increased lift simply because it has a different part number.

Simon
The 180/190 cams have greater lift and a larger overlap than the ones fitted to the 177 Rover.

This is achieved by both a decrease in the lobe separation and an increase in the lobe height, I measured three sets of camshafts about five years back when I revived a very early commission number ZT190 that had suffered timing belt failure.

In addition, the static timing as provided by the camshaft front belt is different.

I hope this clarifies things a little

Brian
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Old 24th July 2018, 19:06   #16
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Not true Brian. The 190 has zero overlap, the cam timing numbers are different though -ie the valves are open longer, hence the cams are different.
It may be the 177 has negative overlap - hang on, we've had this dicussion before, someone couldn't understand it then either?
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Old 24th July 2018, 21:55   #17
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Thanks for all the input guys will be swoping engine and ecu will get the belts ect done as well
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Old 25th July 2018, 08:11   #18
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... -ie the valves are open longer, hence the cams are different.
It may be the 177 has negative overlap - hang on, we've had this dicussion before, someone couldn't understand it then either?
Thanks for this Huw.

According to RAVE, the 190 exhaust valve is open for exactly the same period as that on the standard Rover 177 engine. It does, however, open 4 degrees later and closes 4 degrees later.

It is difficult to be certain about the inlet valve since RAVE says that on the 190 it opens at minus 2 degrees BTDC which is a non-standard and ambiguous expression and must surely be a typo. What the figure is supposed to be is anyone’s guess.

RAVE gives a single value for maximum valve lift on “2.5 litre engines”. There is no mention of greater lift on the 190 PS variant.

Simon
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Old 25th July 2018, 18:02   #19
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RAVE gives a single value for maximum valve lift on “2.5 litre engines”. There is no mention of greater lift on the 190 PS variant.

Simon
Today I have taken a spare 190 cam and a 177 cam and mounted in turn in my lathe.

Using a dial gauge mounted on a magnetic base, I measured a lobe from the 177 camshaft, then zeroed the clock.

I then mounted the 190 camshaft in the same way and measured the same corresponding camshaft lobe, the difference in the two measurements were .065" or 1.651mm if you prefer metric measurement.

Doesn't say that in RAVE does it Simon?, I must have been dreaming then

Brian
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Old 25th July 2018, 22:05   #20
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all i know which is important to me is my 190+ is defently a much faster car the 2.5 160 as had a remap duel v8 style exhuast and induction the car as also been well looked after by its previous owners but my 190 is much faster car so thanks for all the input i look forwards to reading more as you guys know a lot more than me
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