Motoring Discussion > Highly tuned engines less refined? Miscellaneous
Thread Author: tyro Replies: 14
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New Mon 3 Jan 11 10:44 
 Highly tuned engines less refined? - tyro
I was reading a test drive of the current Kangoo (Dynamique TomTom DCi 110 bhp) and came across the following quote with regard to the 1.5 dci engine:

"It's not the smoothest turbodiesel on the market - but that is in part due to the fact that my Dynamique example was the most highly tuned version, and with 110 bhp comes a gruff note. The standard 75 bhp version has the same capacity and is much quieter and smoother, with the mid-range 90bhp likely to be the best bet if you are looking for a compromise between power and refinement."

I've read a number of reviews and test drives in recent years, but I've never heard the suggestion that an engine tuned to give more power will be less refined.

Is this true? Has anyone else heard this? I'm sure I've never heard that people who got their engines remapped suffered a loss in refinement.
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New Mon 3 Jan 11 10:58 
 Highly tuned engines less refined? - AnotherJohnH
I understand that is the case with the VAG PD engines.

They start gruff at 90bhp or so, and need a dual mass flywheel to smooth out the lumps in power delivery long before they get to 170bhp.
Last edited by: AnotherJohnH on Mon 3 Jan 11 at 10:59
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New Mon 3 Jan 11 11:22 
 Highly tuned engines less refined? - Old Navy
Seems logical, the more the power output for a given engine size, the harder it is working.
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New Mon 3 Jan 11 11:34 
 Highly tuned engines less refined? - Zero
I'd go with that thought as well. I have severe doubts about these high power output from low capacity engines. Its not natural.
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New Mon 3 Jan 11 11:43 
 Highly tuned engines less refined? - Old Navy
I don't like small highly stressed engines. I find a 1.6 to 2.0 120ish bhp turbo diesel adequate for my use. The good one are as refined as a petrol engine these days and you don't have to rev them to screaming point to get anywhere.
Last edited by: Old Navy on Mon 3 Jan 11 at 11:44
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New Mon 3 Jan 11 12:07 
 Highly tuned engines less refined? - Armel Coussine
>> Its not natural.

AAAARR... 'tis flying in the face of nature, that be...
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New Mon 3 Jan 11 15:02 
 Highly tuned engines less refined? - DP
I'd suggest there was something amiss with the test car. I had a Megane with the 106 bhp version of this engine, and it was peachy smooth. So is my father-in-law's 1.5 dCi Qashquai.
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New Mon 3 Jan 11 15:20 
 Highly tuned engines less refined? - rtj70
I'd read before that moving to Euro V emission regulations meant engines were going to lose some of their smoothness we've got used to. It would take time for the manufacturers to design that smoothness back in.
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New Mon 3 Jan 11 15:40 
 Highly tuned engines less refined? - Skoda
If it's the same capacity, so stroke and bore aren't changing and i'm guessing it's the same head, that could mean the same cams (how likely is that? Maybe a fair chance with adjustable timing on intake and exhaust cams these days?).

So that means bolting on a bigger turbo and bigger injectors maybe then fiddling with the ECU?

It makes sense to me that there would be a sweet spot for all that hardware and the twiddling would take it out of that sweet spot, trading noise or whatever for power.
Last edited by: Skoda on Mon 3 Jan 11 at 15:40
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New Mon 3 Jan 11 16:50 
 Highly tuned engines less refined? - bathtub tom
It's a four-pot, so it's inherently unbalanced. Increase the power and you get a bigger bang.

Bigger bangs + imbalance = roughness.

Seemples!
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New Mon 3 Jan 11 16:55 
 Highly tuned engines less refined? - Focusless
The 200bhp petrol turbo we had in our Leon 2.0 TFSI seemed pretty refined, more so than the ~130(?)bhp lump in my 2.0 Focus mk1 anyway :)
Last edited by: Focus on Mon 3 Jan 11 at 16:56
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New Mon 3 Jan 11 17:02 
 Highly tuned engines less refined? - corax
It helps to incorporate balancer shafts in four cylinder engines for smoothness like the Honda VTEC engines, incredibly smooth even at silly RPM.
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New Mon 3 Jan 11 17:10 
 Highly tuned engines less refined? - Bellboy
usually
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New Mon 3 Jan 11 17:14 
 Highly tuned engines less refined? - Skoda
How do motorbike engines keep it so smooth with only twin cyls but with the redline up in the clouds? That must take a few engineering tricks.
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New Mon 3 Jan 11 17:40 
 Highly tuned engines less refined? - corax
My mates got a Suzuki intruder, a cruiser bike with a 1500cc V twin. Big pistons, and yes it doesn't rev that high :)

I love the sound of fast V twins. At night in the summer I can hear groups of bikes racing down the A12, the sound of 4 cylinder screamers interspersed with the bassier V twins on the over run in the distance.
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