Dissapointing Power Output (Dyno Run)

[lwalling]

Doug,

The car was warmed up before the "testing" described was done.

I think it would be "cool" to vary the a/f ratio in realtime and be able to tune the car on a dyno - going to try to learn more about the Haltech computer but also emailed ESM to ask about a leaner chip. 10:1 is rich!

Thanks.

the Elan has to be up to running temp for the timing to be proper in Diagnostic-mode while setting the timing.

You should not look for any difference at diagnostic idle; you'd have to take the car out of d-mode and drive it around for you to tell any difference.

Alan could perhaps be persuaded $$ to make a custom chip with mixture targets closer to nirvanna but then you run the risk of leaning out the car unless you are watching on Elanscan and wideband O2 sensor . . .

[ESM]

I have run a fuel enrichment of 12:1 rather than 10:1 but a little knock shows up - not much but enough - so I have decided to tune both the spark advance and fuel enrichment tables on a dyno rather than risk long term reliability. The plan is to do that in the next month or so.

The a/f reduction did seem to help performance.

[F1 LOTUS]

The change from closed-loop to open-loop mixture control seems rather abrupt, would it be possible to change any of the parameters to good effect? Maybe this would have to be combined with a faster-acting O2 sensor (if such a thing's available) though?

[ESM]

The standard oxygen sensor is a narrow band item only useful for holding an air fuel around the 14:1 level. So as soon as the ECU determines that an enriched mixture is required it switches to closed loop because the mixture will immediately be outside the sensor's operating range. A wide band sensor could be fitted but it would need a bit of programming to make the ECU use that as default and I don't think it would be worthwhile. Remember UK SEs are pretty powerful and they don't have oxygen sensors at all (usually) and operate solely in open loop.

I think Lotus went for a very conserative boost setup to give strong reliability and a big safety margin to allow for rash owners fitting of MBCs, FCDs and dodgy chips. There is more power to be had from the engine by tuning the high boost a/f ratio and spark advance on a dyno - I have the electronic hardware for on the fly mapping changes all ready I just need to get my act together and book some dyno time.

[Dave M]

One issue may be the fact that you have dynoed on the Mustang and other numbers were attained on other brand dynos. There can be a variance between dynos, and I've heard that the Mustang can produce lower (though accurate) figures than say a DynoJet or the like. My car will be completed shortly and I plan to run it on a Mustang dyno (the shop that is tuning my car), and then on a DynoJet (the place where I had dyno work done twice before). I'm curious to see the difference in dynos, and that way I can also compare apples to apples as my previous dyno results were only on the DynoJet.

The other possibility may be the person who ran the dyno session. You mentioned there were issues with getting tach signals and the car wasn't pulling much more than 6500 rpm. Maybe the resistance was set to high on the dyno? From what I understand of the Mustang, it can produce different "loads" on the car. Maybe yours was wrong for the Elan?

[Dave M]

After looking a little more at the results, 10:1 seems VERY rich. Remember that too rich can be almost as bad as too lean. This could be another factor in your results. FWIW, my shop recommends tuning to 12.5:1.

[ESM]

10.1:1 is very rich but its what the fuel enrichment is programmed at in the ECU for 'high' boost. I'm sure 12.5:1 or so is more appropriate but since the timing was presumably set for 10:1 I want to remap both at the same time.

[lwalling]

Taxgeek, did you ever run your car on the Mustang? What were your results?

ESM- Did you ever get to build a new program running on a dyno to improve output? My car is still weak :).

[ESM]

A dyno is booked for Wednesday.....

[lwalling]

Excellent. I look forward to seeing the results!

[Doug]

A dyno is booked for Wednesday.....

[Guest]

10:1 is way too rich. You should be fine 11.5:1 or so for spirited driving.

Dave,

I think 12.5:1 is still a little on the lean side for track activity.

[Don.Hasi]

iwalling: you are searching for any reasons for bad turbodynotestings?

If so, check the following too:

- which software has the dyno himself? Is he actual?
- has the tester experiences with turbos? Is there some extra-air (fan) done to the intercooler?
- in which gear has he tested?

In your combination the car must go very better than the stock ones, regarding everything with your turbogadgets is fine (hoses, wastegates, ... what ever you have inside to let the engine run)

hope it helps.

Kind regards

[ESM]

Another item to consider is the intake air temperature. When we were tuning up the mixture on a dyno the intake temperature sat at over 90°C during the runs! The ultimate power recorded suffered a fair bit.

[philip_sloper]

The performance gains in terms of the way the car feels is huge, it's like a night and day difference.

Your original comment suggests that the car is more powerful than standard. Are you absolutely sure that the dyno is calibrated correctly? They are often used by tuners to compare outputs when mods and adjustments are made, so repeatability may be considered more important than absolute figures. This site discusses them in detail:

www.dynamometer.fsnet.co.uk/index.htm