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Dyno results vary between testing stations, but comparing various states of tune might be instructive - especially if contemplating more expensive work on cams and valves etc. In this case minor modifications gave 83.2 kW at the wheels.

My Sud's rbuilt 1991 16V boxer was modified with a 1730cc rebore, Squadra Tuning ECU chip (98 RON fuel) and a K&N pod filter (because the original filter wouldn't fit). The original 16V exhaust system was kept, but a new cat was fitted and the manifold fettled around the inboard brakes (on a 16V gearbox). No blueprinting or compression changes.

It's not clear how much engine power was lost to give 83.2 kW at the wheels. Estimates on this seem to vary. My only yard sticks on the same dyno are that a 2001 156 Twin Spark (originally 114 KW) produced just over 84 kW on the same night and my original 1.5 Ti motor (84hp) gave 41 kW. Both comparison motors were likely tired or even exhausted. So....I'd like to believe this 16V is usefully more powerful than it was in 1991 (92-95 kW), but what is normal?
 

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This is all a bit difficult as there are so many starting points. Firstly in the UK most people work in HP. kW's is pretty much unheard of. Easy to convert with a calculator.

The other factor is rolling road losses. Just in my head I tend to work on a factor of 1.2. So.... if the wheel HP is 100 then the engine HP is 120..... simples. But you hear all sorts of figures and clearly all rolling roads not only supposedly read differently - but also different wheel to engine factors are used. At least that is how I understand it. The only reasonably meaningful comparison is cars that have attended the same rolling road and what their power figures are. Locally there appears to be folklore as to whose rolling road reads high (flattering) and whose reads low (probably nearer reality). I always go to the same rolling road so that way I can make my own comparisons. There is also a decent Alfa tuner near by - they always take their cars to the same rolling road - so I can compare what I have done, sort of, with figures he gets for his (very developed) work.

Here is my situation. I had my 33 back from the rolling road last week - and it said 170HP engine and 142 torque. To work that back I took 170HP x 0.8 and then converted it to kW. It equalled roughly 101kW.

This is how my engine is configured. 1800cc, high compression pistons, Omex ecu, wasted spark, original 16v manifold (slightly modified) but large straight through system (no cat), BMW injectors, trumpets with large filters, race alternator, ported heads, lightened flywheel, fully balanced, 1.2 Sud gearbox, big wing sump, standard cams, 146 oil pump, baffle plate and so on. As you can see there are a few things in there and it probably is reasonably accurate at around 170HP. Clearly as you know the factory figure for a standard (non cat) 16v was 137HP. Having spent £1000's I have achieved what I feel is a realistic +33HP. It feels to me to be about 170HP compared to other cars that I am aware of.

Interestingly, I build almost exactly the same engine about 10 years ago, minus the ported heads. On the same rolling road I achieved 169HP. I don't think the porting I had done, was particularly scientific and am pretty certain there was no flow bench work. So, although these heads were expensive (impulse buy!) in my mind they have given me 1HP...... eek!

Going back to your car, if I work the maths - it comes to 134HP. From the web you can see that 33 16v cars with cats were 98–101 kW (133–137 PS; 131–135 bhp) at 6,500 rpm when new, supposedly. Clearly I have used some pretty arbitrary factors in coming up with a figure, but you have to use (guess) something. One way of looking at it is that with the work you have done - it is back in line with what the factory first produced. Does that make you feel good / bad / happy / sad?

Let me know your thoughts. :)

Edward.
 

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Hi, you know we cannot have a fixed factor to calculate losses,
they vary in many different ways, but in a typical situation on rolling road
in 4th gear, and if the rolling road is quite good, it goes like Edward said.

And some people talk about something bigger than 20% losses, especially
on old car (the oil and the steel used in transmission get better every year):

> 22% or 23% losses for Alfa 33 (small penalty for conic gear pair)
> 23% alfa 75 losses for Alfa 75 (small penalty for conic gear pair and rubber joint)
> 20% alfa 145 (may be 21% on smaller engine+big gearbox I don't remember)

So..
if you assume 23% (optimistic), 83,2kW / 0,77 = 108 kW = 147 CV
if you assume 22% (prudential), 83,2kW / 0,78 = 106,7 kW = 145 CV

It seams quite consistent with the mod you have done,
especially if you started from 16v with cat version camshafts (132 CV ??)
and the car still have a cat in the exhaust system.
 

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Wow, you've done some work on your 16V! Yep, we've gone metric in Australia, at least for some things. An online conversion tool says my engine produced 113 hp (DIN) at the wheels which makes your math about right, given that the 1.2 factor translates to a 17% power loss to the wheels. Obviously I'd prefer the next post's 22% figure, but your more cautious approach still gives slightly above the 95kW/132hp Australian specs quoted in the factory handbook. So...I'm happy in a small way. Not so happy is the 156 owner who has to round-up 18 missing horses.:smile: Oddly, conversion tool turned 95 kW into only 129 hp (hp to kW: x .7354988). Editors! I'm not sure if Australia had any non-cat 98 kW cars officially imported here. Happy motoring.
 

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Yep, and hopefully all that work and all the wait should come to something tomorrow. Re-test in the morning for the MOT. It failed on 2 very small items which were fixed pretty quickly. The car looks pretty good and goes pretty well, on the limited runs I have been able to do..... but now is where the hard work starts.

I have a long, long list of things that will be done, as a bit of a treat for getting past this stage. Parts and ideas that have been sitting on the shelf for years.

Once that is all done it is back to progressing work on the supercharged engine - which is incidentally coming along nicely at the moment as well..... :)
 

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Thanks RS FB, now to try and track down the misfire..... boring.

Where to start? Will start perhaps with the Omex timing wheel and then move on to other things. Let's see....
 
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