Dyno discrepancy

[Grundo Farb]

In preparation for fitting a 45 DCOE to my volumex I had the car baselined today on a dyno with the hubs connected directly to the units (so not a rolling road). I haven't scanned in the results but I am rather devastated by the results in that peak hp at the wheels is 80.7hp (5350 rpm) and peak torque is 136Nm (3250 rpm) while these peaks coincide with the quoted peaks of 5500 rpm 135hp and 3000 rpm 206Nm I can't help wondering where all the bhp have gone! I have just put on a 2.5 inch 4-1 stainless exhaust with two large straight through resonators so am all the more perplexed. The car feels responsive and runs well but wonder if this result is normal or potentially a calibration problem although the operator seemed to be quite convinced it was correct. The oxygen sensor has the engine running very rich up until 5000 rpm (0.7 Lambda - volts I guess) then it goes very lean (1.2 Lambda at 5850rpm).

My question is how much is expected to be lost between the flywheel and wheels and due to the age of the motor - albeit in good nick with new pistons 6 years ago and the head inspected last year. All info I find only quotes 'at the flywheel'.

[len_newstrum]

In preparation for fitting a 45 DCOE to my volumex I had the car baselined today on a dyno with the hubs connected directly to the units (so not a rolling road). I haven't scanned in the results but I am rather devastated by the results in that peak hp at the wheels is 80.7hp (5350 rpm) and peak torque is 136Nm (3250 rpm) while these peaks coincide with the quoted peaks of 5500 rpm 135hp and 3000 rpm 206Nm I can't help wondering where all the bhp have gone! I have just put on a 2.5 inch 4-1 stainless exhaust with two large straight through resonators so am all the more perplexed. The car feels responsive and runs well but wonder if this result is normal or potentially a calibration problem although the operator seemed to be quite convinced it was correct. The oxygen sensor has the engine running very rich up until 5000 rpm (0.7 Lambda - volts I guess) then it goes very lean (1.2 Lambda at 5850rpm).

My question is how much is expected to be lost between the flywheel and wheels and due to the age of the motor - albeit in good nick with new pistons 6 years ago and the head inspected last year. All info I find only quotes 'at the flywheel'.

Just guessing: Where did your specs come from? There is a vast difference between the way horsepower/torque curves are determined in the US and Europe. The European way is much more honest! US horsepower is measured by essentially "tuning" the engine at each of a number of discrete points (i.e., rpm) with no exhaust system, etc, rather than just running at a number of points with an "as installed and single settings" configuration. Anything to sell cars. At least that was the way it used to be done.

[Grundo Farb]

From the lancia volumex supplement. It includes a characteristic curve for the torque and power DIN and then has a table with max torque and max power. These specs are consistent with the numbers in the Guy Croft manual and all other literature I've read about the volumex.

[Jim Fierst]

I am by no means any authority but I have always heard that the loss from the flywheel to the rear wheels is 20%.
Somerthing sure seems wrong because what you posted is about equal to a normal stock FI 2L.If what I read was correct (that the VX supercharger put out 6 lbs of boost) then your HP number should be over 100.
Here are a couple of documented dyno results from folks that do not normally post here.
Csaba Vandor dynoed several 2L FI Fiat spiders which are rated at 102 HP and 110 FP of torque. They consistantly produced 82 rear wheel HP.
Jim Seablod had a stock 2L FI Fiat he turbocharged ~8 pounds of boost and got 121 rear wheel HP and 139 Ft pounds of torque.
There are so few volumex cars here that I have not seen anything posted.. Maybe Val D. or Tom B. who have them may chime in.

[len_newstrum]

My question is how much is expected to be lost between the flywheel and wheels and due to the age of the motor - albeit in good nick with new pistons 6 years ago and the head inspected last year. All info I find only quotes 'at the flywheel'.

According to my Marks Mechanical Engineering Handbook, the input/output efficiency of lubricated bevel gears is on the order of a half of a percent per gear. That would amount to no more than about two percent for a transaxle (transmission plus ring&pinion set). The CV joints and wheel bearings might add a percent or so to that. Overall, not much.

As for engine condition, do a compression test. If all cylinders are close to being the same and within the factory established band, your engine should be just as efficient as when new. Anything else is just tuning errors.

Len

[rossocorsa]

From the lancia volumex supplement. It includes a characteristic curve for the torque and power DIN and then has a table with max torque and max power. These specs are consistent with the numbers in the Guy Croft manual and all other literature I've read about the volumex.

which supplement do you have that sounds interesting not sure it's the one in common circulation(?)

[Grundo Farb]

I dare say its the same supplement as the one in the downloads section on this site "Volumex Technical Information". I can't download it so can't verify but assume it is.

Sounds like the dyno operator has not set it up correctly as the compression is fine and the car runs extremely well. I have driven two others and they are all comparable. I think he might have been 'aiming' for what he thinks the HP should be so he can charge me to tune the car.

Quite frustrating though.

[DJ]

I can't download it so can't verify but assume it is.

Why not?

If it tells you that you aren't allowed to download, try logging in a second time. That normally takes care of the problem.

If it's something more than that please let me know so I can deal with it.

I promise this will get resolved eventually. :mad:

[jazzygeoff]

Hey,

I had my VX on a dyno a while ago, wasn't really to measure HP but rather get the timing and a few other odds and ends sorted out.

She aparently pushed out a painfull 101 wheel hp not sure at what rpm tho and I suspect the reading was a little low as I was not there and my mechanic said he remember see'ing 101 hp on the screen while running it :)

I have just sorted out some fuel pressure issues and am busy finishing off the Nitrous install so will be taking her back to the dyno shortly. Will try post a proper chart of how she does.

[Jim Fierst]

A question for all the Volumex owners .. Did these cars come equipped with any kind of boost pressure gauge??
It would be helpful to know what the supercharger was putting out on your dyno runs.. I found that a boost gauge and and an air fuel meter were absolutely essential when I was building / tuning my turbocharged Fiat Spider. I can adjust the boost via the waste gate tension.
See dash picture below ,right most two instruments .

[jazzygeoff]

Hey Jim,

I have since added a boost gauge as VX's dont have one standard. The car was boosting at around 0.4 bar at the time of my first dyno run, and this was also with the compression lowered a few %.

I have since upped to boost to 0.6 by adding a adjustable bottom pulley that now allows me to change gear sizes for more or less boost. Not an easy or quick change.

So I'll be very keen to see how huch hp gain there will be for the 0.2 extra boost. I am also trying to get an air/fuel gauge before the next run.

[Grundo Farb]

Do you have any photos of your setup? where you've put the boost gauge, what layout of your engine is etc - it would be very useful if you have.

After all the helpful comments on here I am fast coming to the conclusion that the error is with the dyno setup or operation. I've driven three other VX's and they all feel the same as mine - but will do a compression test to find out.

[LanciaDave]

Yes, no stock boost guage. Parasitic losses from flywheel to 'rear' wheel horepower average around 20% depending on the exact car, etc, but still go up from a Minimum of 10 to 15%. US 2L w/smog & carb. shows 80-90hp @ the flywheel, w/FI around 100, European 2L 100hp carb & 120 FI, VX (not sold in US) around 135hp, all at the flywheel.
It sound like you're not getting enough power from the engine. Your fueling (pump maybe?) isn't what it should be. I suspect your engine has some fault, could be timing, ignition, compression, but not all is tip-top somehow.
I can't remeber all my conversion factors, but isn't .4 low? What is that in psi? Perhaps it's time to rebuild your VX (the supercharger itself)?
You should be able to show at least around 100hp at the wheels.

Dave
a 'couple' Beta's, etc.
Oregon, USA

[Scott H]

Your numbers sound pretty close from what I have seen. Eddy brake dynos are sometimes called the "heart breaker dyno" for this reason. But, they are the most accurate.

All dynos take into account various correction factors and can give some deviation for or against. Those who are in a quest to find the biggest number will use an inertia dyno like Mustang or DynoJet. Not necessarily the most accurate or the best for tuning but it is better than the little blue pill if that is what is needed.

My 1.8, NA, 32/36 DGV, 40/80, 9.9:1 CR turned the mid-90 HP on a Dyno Dynamics. It was about what I expected.

HP rating protocols have been all over the place until SAE's J2723 in 2005. It smacked a few car co's around with the numbers they were claiming. All were accurate but under different methods and corrections. I really don't know what was used by Lancia in the day but I guess it was rounded up a bit. A lot left off accessories and ran with an open exhaust for example. Then take out your 15-20% losses and it gets you in the ballpark.

Wikipedia's article (http://en.wikipedia.org/wiki/Horsepower)on HP is pretty good.

This is a good book too.
http://ecx.images-amazon.com/images/I/51Z75h2FNRL._SL500_AA240_.jpg

>Scott

[Grundo Farb]

Your numbers sound pretty close from what I have seen. Eddy brake dynos are sometimes called the "heart breaker dyno" for this reason. But, they are the most accurate.

All dynos take into account various correction factors and can give some deviation for or against. Those who are in a quest to find the biggest number will use an inertia dyno like Mustang or DynoJet. Not necessarily the most accurate or the best for tuning but it is better than the little blue pill if that is what is needed.

My 1.8, NA, 32/36 DGV, 40/80, 9.9:1 CR turned the mid-90 HP on a Dyno Dynamics. It was about what I expected.

HP rating protocols have been all over the place until SAE's J2723 in 2005. It smacked a few car co's around with the numbers they were claiming. All were accurate but under different methods and corrections. I really don't know what was used by Lancia in the day but I guess it was rounded up a bit. A lot left off accessories and ran with an open exhaust for example. Then take out your 15-20% losses and it gets you in the ballpark.

Wikipedia's article (http://en.wikipedia.org/wiki/Horsepower)on HP is pretty good.

This is a good book too.
http://ecx.images-amazon.com/images/I/51Z75h2FNRL._SL500_AA240_.jpg

>Scott


Ballpark for Jazzy Geoff but not quite for me, as Jazzygeoff stated 101hp would be what I expect. 80hp is a reduction of 40% which I haven't heard of unless theres a systematic error - either with the engine in its compression or the dyno. It was also a hydraulic dyno not an eddy brake dyno.

[Grundo Farb]

Yes, no stock boost guage. Parasitic losses from flywheel to 'rear' wheel horepower average around 20% depending on the exact car, etc, but still go up from a Minimum of 10 to 15%. US 2L w/smog & carb. shows 80-90hp @ the flywheel, w/FI around 100, European 2L 100hp carb & 120 FI, VX (not sold in US) around 135hp, all at the flywheel.
It sound like you're not getting enough power from the engine. Your fueling (pump maybe?) isn't what it should be. I suspect your engine has some fault, could be timing, ignition, compression, but not all is tip-top somehow.
I can't remeber all my conversion factors, but isn't .4 low? What is that in psi? Perhaps it's time to rebuild your VX (the supercharger itself)?
You should be able to show at least around 100hp at the wheels.

Dave
a 'couple' Beta's, etc.
Oregon, USA

0.4bar is 5.8psi, its supposed to be around 6psi so thats about right - all about flow not pressure anyway so a pressure gauge isn't that useful. Fueling is fine and there is no fundamental tell tale signs that the car is not tuned well.

[rossocorsa]

really the vx has never been about out and power anyway it is all about a wide spread of torque driven correctly it is a fast and relaxed experience out and out performance if revved like hell is not much if any different to a standard 2 litre Beta

[jazzygeoff]

Hey,

Ok well I was on the Dyno again today, and got some positive and negative results :scratch:

We never actually ran to measure HP but rather make sure the AFR's are in order before we starting gassing it.

But anyway, she did a resonably impressive 110 HP at about 5000 and then started to surge and misss :mad: My AFR was sitting at about 7 or 8!!! So running rich as hell.

My mechanic origannly re-jetted the carb but looks like he went to big, after much fidiling with the regulator it's been decided to go with a slightly smaller jet. (just gotta find one first)

So I will be taking her back later this week and hopefully get around the 125-130 mark with the AFR's sorted? A bit confident maybe?

And then with the Nitrous I am hoping to get around 150 HP :cheers::cheers: