I have so much data i dont know where to start typing…
Shall we start with the headline numbers?lets go with that;
At PLs dyno, we dynoed the car before the headswap, cams, porting -
150lbft, 188bhp
the best After result was
170lbft, 224bhp
+20lbft, +36bhp
there was an issue with the throttle close at top end which was causing a ‘rollover’ which i found in logs. got that fixed on revisions and we made a couple of tweaks on the cam timing and ignition at that top end. this has yielded better results.
yesterday i took the car to my local dyno (every dyno is different, different weather, day, strapping technique etc).
On the ‘original’ map (i.e, the 170 + 224 i left PL with). i got 169lbft and 205bhp.
on the ‘best map’ of the day from revisions, got 171lbft, and 213bhp.
theres various ways to interpret these results.
Firstly, these are estimated at the flywheel, so different conversions happen. (i dont know PLs, but the peak WHP was 190 on my local dyno, approx 11% drivetrain loss).
the torque was spot on though, almost throughout, so could just be an estimation loss difference.
Taking visual datapoints across the dynos they line up well. (until peak). (*MB = the name of local dyno)
Torque in Lbft:
4000rpm - PL 167, MB 168
5000rpm - PL 163, MB 164
6000rpm - PL , 162, MB 162
7000rpm - PL 158, MB 157
7500rpm - PL 154, MB 144 <<
so one way to interpret, could be that from revisions we found an extra 8hp at peak, which could mean i would now be 232bhp on PLs dyno. (a total improvement of 44bhp)
However, theres another way.
I have been on this dyno before, 12 months ago. (also in my ‘‘190 configuration’’)
i put down 167lbft and 200bhp on that day (170whp)
Based on these numbers, it looks like i have made very, very small gains.
Whats really interesting, is that the peak BHP and Peak torque @ RPM are identical! unchanged. we havent shifted the powerband to the right. nor are there any losses. this is odd…
lets show some graphs:
Last years dyno (BBR 190 package)
Yesterdays dyno
Showing the ‘‘PL original’’, and the final revision comparison.
ive got another 4 plots across other sheets as well, but this for sharing is the most easy to read visually.
But they all follow this same trend: 6800rpm - peak bhp, then a bhp plateau and a torque cliff for 1000rpm.
i think peak power is up about 13bhp, and shifted about 300rpm to the left. How?! The math says it should have gone the other way.
Investigating numbers
I’m trying to figure out whats going on (flow wise) here. checking the MAF data it confirms the graph - ramps up rapidly to about 150g/s to 7000rpm, then barely moves/occilates between 145 to 160g/s to redline. engine is being choked. But where?
Size Analysis
so lets unpack a little from the earlier data. we know that between these dynos, the following has happened, in terms of size/diameter/capacity of airflow.
- new ND2 inlet manifold. larger plenum, larger dia runners, align to ND2 head
- ND2 head fitted. inherently bigger inlet ports and exhaust ports
- ND2 head ported. confirmed increase of about 1mm on intake side, and a few mm on exhaust side (per port).
- ND2 has larger valves, approx +0.5mm dia per valve
- High lift cams.
These all point to two trends occurring: Less torque in the mid range. More torque (therefore bhp) in the top end. Heck a typical nd1 vs nd2 dyno shows that well enough!
We dont see that.
In fact if you overlay the 2025 dyno and the 2026 dyno from the same shop, you could be fooled into believe the only tuning work done was a new redline, some 700rpm later, and some premium fuel.
*Note, this isnt a complaint to any workmanship, tuning, or parts on the car from anyone involved. Everything seems to be worked as expected and car drives great. i am just trying to unpack what i am seeing so i can improve the results further. its all a pursuit of power!
Capacity Numbers.
Looking at every item ive measured and running it through airflow laws (mainly taken from Graham Bells work) i get the following:
in short, nothing is showing as a limiter for the airflow seen at peak through the MAF. the tighest flow is the exhaust port (which has already been ported heavily) but itself isnt yet a limitation.
Part2 coming soon… more charts and data on this topic! but ive hit word limit for 1 post 