Author Topic: Extending the revs.  (Read 3279 times)

Jocko

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Extending the revs.
« on: July 21, 2018, 05:14:15 PM »
Today, for the first time, I had the wee car up to 4,500 rpm. Just for the sake of it, I might add. I never feel the need. Surprised just how well it started to go North of 4,000 rpm. You can feel it, as they used to say, "come on the cam". I could get used to it!

culzean

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Re: Extending the revs.
« Reply #1 on: July 21, 2018, 05:47:20 PM »
Today, for the first time, I had the wee car up to 4,500 rpm. Just for the sake of it, I might add. I never feel the need. Surprised just how well it started to go North of 4,000 rpm. You can feel it, as they used to say, "come on the cam". I could get used to it!

My experience of iDSi 8 valve engine is that it was better low down (more tractable and urban friendly) than the iVTEC 16 valve but that it 'ran out of steam / got a bit breathless' above 4500 revs (iDSi does not have any cam change mechanism fitted).  On the other hand the IVtec is not too good below 2500  and the more you rev it the better it gets,  and the 'getting better' extends right up to red line. This is typical of 2 valve per cylinder vs 4 valves per cylinder engines.  For the Jazz I actually preferred the iDSi which suited its purpose better (as a mainly urban car ). I traveled many motorway miles in iDSi Jazzes and never really found them lacking, as 70mph was around 3200 rpm in 5th.   Maybe it is the Psuedo Atkinson cycle on iVTec that spoils it lower down,  I think 12/16 valve VTec would have been better for drivability rather than keeping all 16 valves working all the time and holding them open at low revs to pump a lot of the 'go juice' back into inlet manifold.  IMHO fuel consumption of iDSi can be better than later iVTec engines, and power on iVTec comes in too high up the revs for most people to use (especially my wife who never gets above 3000).
« Last Edit: July 22, 2018, 02:14:45 PM by culzean »
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

MicktheMonster

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Re: Extending the revs.
« Reply #2 on: July 21, 2018, 08:11:59 PM »
Today, for the first time, I had the wee car up to 4,500 rpm. Just for the sake of it, I might add. I never feel the need. Surprised just how well it started to go North of 4,000 rpm. You can feel it, as they used to say, "come on the cam". I could get used to it!

You should get it up to 4500 revs every day, they sound great and go like a hairy bear!

Jocko

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Re: Extending the revs.
« Reply #3 on: July 22, 2018, 02:10:57 PM »
Gave it another blast today. 5426 rpm in 3rd, for 73 mph.
Rev counter reads 3,000 rpm for an indicated 70 mph in 5th, so culzean's 3200 rpm for an accurate 70 mph is probably about right. 1.2 i-DSi is s sweet little engine.

smilertoo

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Re: Extending the revs.
« Reply #4 on: July 23, 2018, 01:40:37 PM »
Isn't it bad for the engine?

culzean

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Re: Extending the revs.
« Reply #5 on: July 23, 2018, 02:27:09 PM »
Isn't it bad for the engine?

You sound like my wife - the engine is designed to rev that high and unless you do use its full potential sometimes (Italian tune-up) your CAT and EGR can get blocked / stuck.  Think of car engine as its heart,  if you only let your heat chug along at 70 BPM all the time it will get clogged and inefficient - it needs excercise (raising the revs or BPM ) to stay at peak efficiency.
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

Jocko

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Re: Extending the revs.
« Reply #6 on: July 23, 2018, 02:33:17 PM »
The red zone starts at 6,000 rpm, and according to the manual the 1.2 is good for 79 mph in 3rd gear. As this graph shows, it doesn't even reach maximum power until 5,700 rpm.


The engine control system is fitted with a rev limiter to prevent over revving and damage. Add to that the fact I have revved to 5,400 once in two years ownership. There will be Jazz owners who do that every day, several times a day.
I was not worried about doing any damage.

JohnAlways

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Re: Extending the revs.
« Reply #7 on: July 23, 2018, 02:45:45 PM »
I've had mine to the rev limiter a couple of times at one particular spot on the way home but that was in 2nd gear. Just needed to leave a slip road smartish before I impeded cars from the traffic lights. I don't regularly do that but 4500 - 5000 in third is quite common then dodge 4th go straight to 5th.

VicW

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Re: Extending the revs.
« Reply #8 on: July 23, 2018, 03:30:16 PM »
I use the 'S' mode,CVT model, quite frequently and get to 6000rpm  as a norm when doing so. The engine management system will not let you over rev the engine.
Honda bench test their engines at the redline for hours on end to prove that they are capable of being treated this way.

Vic.
« Last Edit: July 23, 2018, 03:56:21 PM by VicW »

Jocko

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Re: Extending the revs.
« Reply #9 on: August 09, 2018, 06:57:46 PM »
Had the car up to 5,400 rpm again today, in third, and I was really surprised how quiet the engine was. Basically all I could hear was wind and tyre noise. Guess if that wasn't there I would have been well aware of the engine, but I had to go by the rev counter and not my ear.

John A

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Re: Extending the revs.
« Reply #10 on: August 10, 2018, 08:26:39 AM »
Isn't it bad for the engine?

Much worse to let the engine labour at low revs / high gear.

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