Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Monty Goes To The Dyno

I've been looking forward to this day as Monty takes to the slippery rollers on a disappointingly wet day.



Anyone following my Duratec Plus 4 tuning journey will know I focused on torque over horsepower, I turned my back on the herd by rejecting the default individual throttle body path in favour of a long runner single throttle plenum, because as we all know its a good spread of usable torque that makes for a fast road car.

Pleasingly, when we focus on the way Monty's Duratec serves up its grunt the results show my slightly unorthodox recipe is delivering the goods, as we can now see Monty makes almost 100% of his maximum torque from 4,000rpm, and all the way to 5,500rpm where peak torque arrives.



More impressive still is he produces 80% of maximum torque output from only 2,500rpm, and from there it's a nice progressive but largely flat climb to 5,500rpm where peak torque lives, but Monty still holds onto that 80% figure all the way to 6,500rpm. The torque is really nicely spread out over the entire rev range that one actually uses on the street, perfect for real world overtaking and pulling out of tight hairpins on steep gradient hill climbs like Prescott.

A little 2.0 litre four banger without the benefit of variable valve timing that produces 80% of it's pleak torque figure from 2,500rpm and out the other side to 6,500rpm (a 4,000rpm window) is a rare thing, and will be why Monty is such a pussycat to drive everywhere, but also offers deliciously crisp throttle response for those giggle inducing squirts past slower moving traffic.



Now let's look at my ECU log, as we can see my hard fuel cut came in at 7,381rpm (blue circle), at the same engine speed ignition timing has been retarded from 28.5 degrees all out at 7,255rpm, to a safe cylinder pressure reducing 23.5 degrees BTDC (purple circles). I'm now completely reasured my ignition timing retardation and fuel cut strategies are working perfectly together to protect Monty's free spinning Duratec, an engine that seemingly would rev to the moon if I let it!



Now we see Monty at 7,255rpm where in theory peak horsepower should reside, the engine is definitely under full load reaching 100 kPA (atmosphere) and proves there is zero air restriction. Monty's air fuel ratio is also Bob on at 12.9:1 and ignition timing is a Duratec ideal 28.5 degrees BTDC all out, we then see engine speed continue to rise passing theoretical peak power at 7,255rpm and topping out at a safe 7,381rpm, at which point my ignition and fuel based rev limiter strategies work perfectly together to stop the crankshaft spinning any faster.



To summarise, Monty is running the.....

* Perfect air fuel ratio (0.877 Lambda - 12.90:1 AFR)

* Optimum ignition timing (28.5 Degrees BTDC)

* And has zero air restriction (100 kilopascals - Atmospheric pressure at sea level)

The torque band is also broad and flat which is exactly what I wanted

But why does Monty's horsepower fall away at just 6,500rpm



There's definitely more to come chaps!

Loving this journey. Looking forward to the next instalment.

Could we see one of the dealers offering a +4 with the “Monty Edition” tune ?

A nice result well done

Very impressive results 👍

That’s great Dave, a sound reward for all your research and hard work. A very interesting thread.
Bob.

Thanks chaps, I appreciate your kind words of encouragement but clearly there’s something a miss at the top end.

My AFR is all good at 12.9:1 and I'm seeing zero air restriction (100 kPa) too, so that's all the fuel I need to mix with all the unrestricted air available in the atmosphere the engine can pull in, in theory that means it should just keep making more and more power, but cylinder pressures are clearly falling off over 6,500rpm!

So that just leaves ignition timing, perhaps I just need to keep lighting the fire earlier and earlier above 6,500rpm and onto 7,300rpm? The trajectory line definitely shows Monty is heading for a theoretical 200hp!



If I add 1 degree for every 200rpm above 6,500rpm that would see me 4 degrees higher at 32.5 degrees BTDC at 7,300rpm, which is probably worth another 10hp.

Or a destroyed engine from knock

I've just checked my log and at 6,500rpm where the power peaks I was running 28.5 degrees BTDC, from there on and all the way to/just past theoretical peak power at 7,300rpm the ignition curve remains flat at 28.5 degrees, there's zero ignition advance added from 6,500rpm up! For the last 800rpm it gets not a single degree more which was largely down to me not being brave enough, I really need to find out how much timing a Duratec can safely take at 7,300rpm under full load?

My other theory (read excuse ) is the rollers and my tyres were very wet, certainly when I entered to dyno cell it stank of hot rubber

Worth waiting for Dave. Thanks for sharing. As you say, low down torque is what gives the thrill on the road and you have certainly achieved that in spades. BHP is a little unexpected but good luck with future improvements.

With substantially greater torque and bhp from our Roadster's we (John V6 and I) also suffered tyre to roller slip given the cars unusually low weight c. 950Kg. We did consider afterwards that extra weight in the form of passenger ballast would have helped. Revival's solution at the time was to squirt almost continuously in Morton's case, WD40 onto the tyres. Holding the car down was another issue which took a little longer on my car with 5 link rear. Worth noting that the dyno will (or should) report slip though hence several calibration runs on each of our cars. A GDI engined Plus 4 was seen on a later dyno session and on a cooler day to need only one calibration run as no slip issues.

Well done Dave. Absolutely brilliant, such compelling and tantalizing data… I think Monty might be being a bit bashful here about revealing his full potential

What’s the date stamp on those rear tyres? Has that compound started to age harden?

Cheers Rog, all Monty's tyres are just 24 months old, I noted when I bought him at auction with just 10,000 miles on the clock Monty was sat on his original Yokos dated 2011, as you can imagine they were very wooden so we're replaced immediately with a nice new set of Continentals.

I'm confident Monty will put down 185hp on a dry rolling road and this does seem to deliver a lot of fun in an 877kg Morgan, especially one serving up such wide spread of torque. As you know I come from a sucession of much more powerful cars, but if I was able to measure them all back to back on a 'Fun Dyno' (if such a thing existed).

Monty would absolutely destroy them all



Thanks Doug

I‘m quite pragmatic about these things, I've said it before and I'll say it again..... "a rolling road is a useful tuning tool, but if you really want to accurately measure output you'd use an engine dyno".

I'd shied away from the power run thing until now as the results can often be very variable, and I'm not one for the pub bragging rights game either. I think age and a bit of maturity (but not too much ) has taught me it's all about the way a car makes me feel, rather than the number it makes on a rolling road. Anyway, it's actually this sort of thing that means a lot more to me than what Monty's engine does, or doesn't do, during the last 800rpm at the very top end of his power delivery, in reality an area rarely visited.



Back to the wheelspin theory, yesterday was indeed very wet, and the way these power shootout days go at Surrey Rolling Road is there's a constant stream of cars going on and off the dyno in rapid succession, this drags standing water through the workshop and onto the rollers. My tyres were certainly very wet as were the rollers during my run, but it was the smell of hot rubber that gave the game away to me.

I consider these Surrey Rolling Road sessions as somewhat of a circus, but for just £45 a run I'd class it as a cheap bit of fun on Saturday morning. I actually have a good friend who's been operating a rolling road for years, he got so fed up with wheel spin issues he eventually upgraded to a Dynapack hub dyno, this completely solves the problem but it's not splined hub friendly, so no good for Monty with his wire wheels.

Back to yesterday at SRR my good mate Dave Jefferies was the first of the two of us on the rollers with Molly, his Z-Cars Mini that has a Civic Type-R engine in the back, a good Honda K20 engine should make 220hp all day long so we were all super surprised to see it record 185hp.





What I can tell you is out in the real world Dave's little 750kg Mini is an absolute weapon, you can see Molly in action here....



Molly and Monty are best friends, they're also very well matched out on the road during their many spirited adventures together, and neither Dave is desperately seeking more power from our super fun and surprisingly rapid retro Q Cars.

We prefer to spend our money on fuel, and drive the wheels off our babies instead