Another Rolling Road Session, Turbo time

[Peter255]

Atom 4 350( ) with boost controller on each of the three settings



My old 2 300( ) for comparison


Its the mid-range where the 4 shines. @3500rpm you go from ~200Ftlb to ~300Ftlb between Atom 2 and Atom 4. But the Atom4 is not worth taking much above 6500, whereas the 2 screams to the limiter @ 8250.

The lvl 3 map is certainly noticeably more aggressive on the road and the figures show you why it feels that way.

More figures to follow.

[Luckky]

Atom 4 350( ) with boost controller on each of the three settings



My old 2 300( ) for comparison


Its the mid-range where the 4 shines. @3500rpm you go from ~200Ftlb to ~300Ftlb between Atom 2 and Atom 4. But the Atom4 is not worth taking much above 6500, whereas the 2 screams to the limiter @ 8250.

The lvl 3 map is certainly noticeably more aggressive on the road and the figures show you why it feels that way.

More figures to follow.

Peter, really interesting thank you, especially the three selections.

What am I missing on the torque, 420m quoted but this seems to be quite different to that, are these figures at the wheels or engine please?


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[CAG3D]

Peter, is the Green line your level 3 on the boost then?


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[John Scherrer]

Torque can be expressed in metric or non-metric units.
Metric is in Newton Metres (Nm), non-metric is in Foot Pounds (Ft-Lb)

Conversion is Nm = Ft-Lb / 0.738 [The ‘/‘ here means divide]

So 420 Nm torque is the same as 420x0.738 = 309 Ft-Lb

[Luckky]

Thanks John, that makes much more sense.


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[Peter255]

Peter, is the Green line your level 3 on the boost then?

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Yes Tony.

Green - Lvl 3 - aggressive midrange "350" map
Blue - Lvl 2 - smoother midrange "350" map
Red - Lvl 1 - lower power map

The lvl 2 and lvl 3 map results are similar from 5000 rpm onwards.

[CAG3D]

Level 3 has a Massive amount of torque early!! I’m surprised it didn’t hit over 350, didn’t Simons hit 365bhp recently?

Did any other 4’s run, without the variable boost?


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[Luckky]

Simons hit 318 at the wheels translated to 365 at engine


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[Peter255]

Full results all calculated adjusted flywheel figures. Cool day.

Ian G K24hybrid s/c Atom (cat)
299 BHP 208FtLb (running too rich)

Ian G K24hybrid s/c Atom (decat)
316 BHP 224FtLb (still running rich, but better than before)

Phil4 K24 Nomad s/c (decat) (18inch wheels)
271BHP 204FtLb (fuelling correct)

Karl V K24 Nomad s/c (decat) (15inch wheels)
275BHP 208FtLb (fuelling correct)

Peter255 K20C turbo Atom 4 350 (decat) with boost cont
lvl 1 240BHP 210FtLb (fuelling correct)
lvl 2 330BHP 285FtLb (fuelling correct)
lvl 3 335BHP 300FtLb (fuelling correct)

[Peter255]

So yes the decat does make a worthwhile difference. I will edit out the reg's and post the traces ASAP, vids to follow...

[CAG3D]

Decat is less the the cat figures....? I think mine feels quicker now, with the standard pipe.


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[Peter255]

Decat is less the the cat figures....? I think mine feels quicker now, with the standard pipe.

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Well spotted! Wrong way around. Corrected.

[robfitz]

Didn’t realise you had the boost controller Peter, did you get it retrofitted or did you have it from the off?

There isn’t as much of a difference in the curves as I thought there might be. What do you tend to use most of the time?

[Peter255]

Peter255


Phil4


Karl V


IanG (cat)


IanG (decat) sorry no torque trace thats the AFR


Vids will need to be edited and uploaded later.

[Peter255]

And a bit of fun.

Handheld noise meter @ 4500rpm @ 45deg 50cm from exhaust tip

Karl's Nomad - 101.3dB
Phil's Nomad - 104.3dB
Peter's Atom - 104.4dB (at the limiter)
Ian's Atom - 116.9dB lol

I seriously hope thats over-reading but as a comparison it should be OK.