Dyno day, Now with figures!!! Options

[emerygt350]

I am still waiting on the graphs, that has the afr across the pull as well. If I remember correctly I think it was 15 max lean climbing to 4k then over 4500 it richens to 11 up at 55 maybe even richer.

Timing is unknown. I have no faith in the marks on my fan. I have tried to verify them but just a 1/4 inch off means my reading is worthless. I have been doing it by ear and off a good idle speed. I suspect I am maxed out on advance, since even the smallest change sucked HP big time. That said, when I checked the timing with my crappy marks I was at 28ish at 3500.

I am also using the retard mode on the 123.

[Van B]

When I checked my 1.8 yesterday, the red mark came back in the window with 38 degrees set on the gun while holding 3000RPM. But since the red mark is the only mark and is aligned for 7.5 degrees BTDC, that would tell me I’m achieving 30 degrees maximum advance. So, yeah, you gotta be close to the limit.

[emerygt350]

Finally got the graphs! I am color blind but at least I can figure out the last run was the best. I am now thinking about maybe spark issues up high. I am still running the ancient coil (123dizzy) and perhaps that is too weak and worn to keep up? It's got a little over 3ohms but I don't know if that means anything about spark strength at rpm.

[bkrantz]

Can I ask how much you paid for how much time?

[Van B]

Other than the wavy A/F line on the last run, your runs look pretty fantastic! If you’re going to put a coil in, do it for the hell of it. You might get lucky in that some extra capacitance helps out, but really man, your car is a healthy boy!

[emerygt350]

Can I ask how much you paid for how much time?

I gave him 160. 11 pulls and he welded a bung in my exhaust for the O2 sensor.

[emerygt350]

Other than the wavy A/F line on the last run, your runs look pretty fantastic! If you’re going to put a coil in, do it for the hell of it. You might get lucky in that some extra capacitance helps out, but really man, your car is a healthy boy!

Yeah, I just feel like something is happening to have such healthy torque but then have the hp fall off like that. Wasn't peak horsepower at 4900 from the factory?

[JamesM]

Finally got the graphs! I am color blind but at least I can figure out the last run was the best. I am now thinking about maybe spark issues up high. I am still running the ancient coil (123dizzy) and perhaps that is too weak and worn to keep up? It's got a little over 3ohms but I don't know if that means anything about spark strength at rpm.

If you could get the AFRs stabilized and dialed in there are a couple more horses hiding in there. Every one of those runs is lean down low, a couple lean enough that I would be worried about head temps, then all runs but the red one go overly rich above 4k rpm

[emerygt350]

Yeah, the issue is adjusting at WOT. The mps is a bit of abracadabra. We tried many combinations to try and get WOT richer at lower rpm and leaner at high rpms but it just ended up being a compromise.

I have sent this on tho Chris Foley as well so maybe he will have some tuning wisdom.

[Van B]

@JamesM these are WOT. Part throttle will be much richer.

@emerygt350 I know I’m a 914 newb, but I’m no stranger to tuning for performance… granted most of my experience is from my days racing superbikes, the principle is the same.

A motor is basically an air pump. And what I see is that your big pistons are drawing a lot of air down low, but as engine speed picks up, Bernoulli is your limit. Some combination of valves (size and lift), ports, or even intake runners are not able to let enough air through. And also, your fuel is not mapped to match the air that is being drawn in.

Also, torque will fall off even as HP climbs. Horsepower is a made up number after all. (Torque*RPM)/5252 = Pretty Ponies.

My advice is not to obsess. The potential of your engine is not much more than where you are currently. And that last little bit you’re talking about are the most expensive horses you can buy!

I would focus on refinement and drivability: flow match intake, exhaust, get a hot coil for fun. And then maybe lighter wheels, etc.

You got a real cool car man, I’m impressed with it!

[wonkipop]

Other than the wavy A/F line on the last run, your runs look pretty fantastic! If you’re going to put a coil in, do it for the hell of it. You might get lucky in that some extra capacitance helps out, but really man, your car is a healthy boy!

Yeah, I just feel like something is happening to have such healthy torque but then have the hp fall off like that. Wasn't peak horsepower at 4900 from the factory?

yes.

torque peak at 3500 105 ft/lbs i think.
just a bit over a 100
looks like your dyno curves are right on there.

its a real monster look your car. love it. (IMG:style_emoticons/default/beerchug.gif)

[JamesM]

@JamesM these are WOT. Part throttle will be much richer.

WOT is really where you need to worry about heat the most as that is where the motor is the most stressed. I have seen 100deg differences in head temps on a type 4 just from dropping the WOT AFRs from 13.7 down to 12.3 across the board.

[emerygt350]

Yeah, we were able to get part throttle tuned in pretty nicely.

I just ordered a new coil from 914rubber, my old one can sit on the shelf with the old distributor. I don't have high hopes but they are inexpensive and so why not...

I wish I had thought to take the air cleaner off. That would have given me a hint towards air starvation being the issue.

[JamesM]

Yeah, we were able to get part throttle tuned in pretty nicely.

I just ordered a new coil from 914rubber, my old one can sit on the shelf with the old distributor. I don't have high hopes but they are inexpensive and so why not...

I wish I had thought to take the air cleaner off. That would have given me a hint towards air starvation being the issue.

Unless the filter itself is clogged I wouldn't think that is an issue, I have seen cars swapped from d-jet to Megasquirt pull ~105 hp on the dyno using the stock intake/air filter once the AFRs were dialed in perfectly. Taking drivetrain loss into account I would say you are probably not to far off from factory output for a stock 2.0.

[emerygt350]

Yeah, we were able to get part throttle tuned in pretty nicely.

I just ordered a new coil from 914rubber, my old one can sit on the shelf with the old distributor. I don't have high hopes but they are inexpensive and so why not...

I wish I had thought to take the air cleaner off. That would have given me a hint towards air starvation being the issue.

Unless the filter itself is clogged I wouldn't think that is an issue, I have seen cars swapped from d-jet to Megasquirt pull ~105 hp on the dyno using the stock intake/air filter once the AFRs were dialed in perfectly. Taking drivetrain loss into account I would say you are probably not to far off from factory output for a stock 2.0.

It's good to know that wonki air canister flows enough for 105.

All this gives me ideas and stuff to shoot for. I mean when there is nothing left to fiddle with half the fun is gone...

[wonkipop]

 wykres_power_lbft_3.php.jpeg ( 50.23k ) Number of downloads: 92

[emerygt350]

 wykres_power_lbft_3.php.jpeg ( 50.23k ) Number of downloads: 92

Is that real or is that a model?

[wonkipop]

 wykres_power_lbft_3.php.jpeg ( 50.23k ) Number of downloads: 92

Is that real or is that a model?

i'm pretty sure its what they are supposed to be when they were new.
its just drawn graphically using modern computer graphics.

i found it when i was looking for the torque power curve of the 1.8
(which is hilarious, all torque and no horsepower)

i came across the same graphs for the 914/6 and the nsu RO80 (original rotary).
funny thing there was they were almost identical.

there is a whole website where you can look up your car from any time / any era,
and the power curves are there.