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172 power differences ........
- Thread starter Captain Slarty
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- 172
Brun, Hi M8
I have also spoken to Luke and he definitely is interested in following, and publishing the results.
Let me spell this out to otheres that may be unsure...
I have a lot of respect for RE rollers. but.............
the figures for the 172s are CRAZY and are NOT to be relied upon until other testing is carried out.
Either, there was a problem with the testing.. or, there IS a technical problem with some of the 172s. THERE IS NO WAY THAT THE DIFFERENCES IN OUTPUT CAN BE DOWN TO ANYTHING ELSE
I would like to test the VVT actuater further. Heres one possibility.
VVT not functioning on lower output cars. That would mean the inlet cam being retarded by 16 degrees.
Possible outcome of this.. Inneficient burn at WOT leading to loss of power and some unburnt fuel passing into exhaust and cat.
Later symptoms may include exhaust failure (Mathew ?? ) at the cat inlet due to higher back pressure than normal (Caused by cat contamination). (The PGTI car (lowest recorded) suffered some exhaust restriction and was blowing out crap....
The CUP racers seem to have problems with vvt actuators too.. on a frequent basis.
Power runs need to be done with vvt in and vvt out to assess this.
that is my best guess at the mo..
Joe.
Hi Guys,
Ben is correct, you can unplug it and try it.
On mine, it made absolutely no discernable difference, that is worrying. I have hooked a multimeter to the unit and can see the signal being applied, it also appears to work at idle as forcing activation at idle caused tractor mode.
However, we have no proof that it is working correctly at the cam phasing device.
I must stress, this is one theory only.. it needs to be tested properly.
Rich, thanks for the offer, all 172 owners interested in this research.. could we arrange another mini rr day and we can arrange a series of pre-run tests, and then actual tests to perform on the rollers.
Also, can the 172 guys at the rr day at re let me know if their car is EU sourced or UK sourced as that may help if a common factor.
Joe.
What I mean is if you know the Actuator is working, why not take a reading whilst in normal operation then manually supply power to the actuator from the start to make the engine lumpy idiling then take another reading..
This should tell you if the phasing is working if the figures are the same ?? Make sense y/n ?
Hi Chavvs, good thinking, but it would not tell the story properly
problem is, even if it shows a load, that does not mean that the solenoid plunger is lifting properly, or, that the oilways are clear, or, that the phasing device is working. The phasing device works from oil pressure from the main gallery feeds via the no5 cam bearing on the inlet. (This is actualted by the solenoid plunger uncovering or covering feed holes only) the cam phaser is then shifted by oil pressure applied to movable vanes inside it.
it really does need to be tested on the rollers m8, unfortunately...
Joe.
to add to that, it may be that the phaser is not actuating at high rpm, high oil pressure etc..
Joe.
Ok, last bit O/T...sorry..
Jon:
Brun was right, the misrepresentation was that NH took the car without my knowledge.......but If you read what I wrote that will be clear now.
The figures. Well yes, the results were not as expected but if I am honest, I want to see what the car does on the rollers tomorrow as that is where it has been on the previous runs.
I expect no lean running @ 6k+ rpm and tentatively predict that there will be a performance increase over the previous 122 ATW showing the mods to be relatively effective and my car to be a
poor performer - at the moment.
I think mileage may be a factor and assuming the mods are effective, hope the relatively small difference between the 12k/142 mk2 and my 12k/145 mk2 was down to the IK not getting enough cool air. The car did not have the scoops fitted as normal..
The rollers are not in @ HP yet, thats why.
As an aside, on the road back from HP however I noticed that I found the gearchange light - especially in 5th - with greater ease, in fact I felt there was a tiny bit more there but I was reluctant to accept the challenge even though I met a friendly Skyline on the way down who was allowing me to use his slipstream LOL!
Brun:
out of interest, how much is the contribution required?
Slugger:
I found the limiter after 625 miles and NH changed the oil (Semi-synth) @ 5k miles.
apologies for the ramble...
Arjun
this is why you should race, not dilly dally about power figures when every rr gets different results. 1/4 mile baby yeah. and jon, nice-swan mate keepin it real for the willys. mine cant be too disimilar in power to yours, we should see if theres any more stock one can get 15 secs or less
Mine was the 20k 151bhp figure for the Mk1 172, and I didnt go above 3.5k for the first 650 miles, and was still very kind to it up until 1000 miles. Most of my miles are motorway miles too, so most of the 20k has been easy on the engine.
I will happily come up for the RR if required.
Mine was also a UK sourced car bought from new.
I remember at the time the 172 came out in the magazines they said the cam thingy operated around 5500 rpm and then switched back to normal mode at around 6700 rpm. Ive still got the mags so Ill dig them out tonight for the exact info. They were quoting from renault press technical info I think.
I always assumed this was the slight kick I feel around 5200 - 5500 rpm? Surely if it was just a coming on cam type of thing it would feel pretty crappy below this? Also sometimes I dont notice this kick at around 5500 rpm and the car feels to accelerate slower - could this be the phase activator not working on occasion?
rob, the kick is the chang over from closed circuit lambda map to open circuit WOT table fueling.
the vvt activates as soon as you come of idle.
Joe
Thanks dood
who had the balck one with 151 ??.. is that uk ??
Joe
I am indeed Paddy! I think Im well chuffed - not as chuffed as when we get the bottom of these power differences! I have to say though Ive noticed a bit of difference in power over the last 2K - its as if the engine is still lossening up - even after 11K. Feels a lot more torquey lower down. A nice good thrash around Bedford seems to have brought it outta its shell!
I have to say you have a nice lookin motor too! Good choice of colour mate
Took mine back to Well Lane Turbo Centre today to let them sort out my 172, they put it on the rollers again and the figure is the same as when the Superchip was fitted 190BHP @ flywheel, told them about the figures at RE performance, they seem to think there was a loss of traction on the rollers, maybe due to oversize wheels, i dont know! but what i do know is the car feels ok, and runs right, has anyone got a explination to this mystery!
Renault Laguna Coupe
Did they give you an at the wheels figure?
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