Dissapointing Power Output (Dyno Run)

[lwalling]

I've modified my little Elan only slighty...

Everest "Chip"
NGK Iridium Plugs
Top End Performance Blow Off Valve/Open Air Filter Element
2.5" Exhaust w/2.5" High Flow Cat and Dynoflow Bullet Muffler
Magic Precat Dissapearing act

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

On the dyno tonight, I found the car is really not making that much power.

HP peak at the wheels was 146hp, and 134ft of torque. This is a dissapointment to me, I was actually expecting to see much higher numbers out of the car. By all accounts this is what it SHOULD be putting out stock going by the published numbers Lotus provided (165 flywheel hp). The A/F is really "fat" as well.

Was the car just "optimistically" rated from the factory? Or.. Is there something wrong with my car ?

View the test data here,
http://www.lukewalling.com/elandynochart_111205.pdf

Thanks for your feedback.

[Doug]

Are you getting full ESM chip boost on the gauge?

Is your engine timing set correct?


Yes--agreed; that is lower than it should be for what you say you have . . . .

[lwalling]

Doug,

Yes, the boost gauge ultimately bounces right on around to a roughly 1 bar.

The timing ? I haven't modified from stock. Should I ?

[lwalling]

Also,

Does anyone else have real dyno results to compare to - someone with similar mods ?

[ESM]

Hi Luke,

Sorry your number aren't quite as high as might be expected.

Doug mentions timing because its known to be critical to power output - I don't anyone advocates changing it from stock just make sure its precisely set to the specified value.

As to other dyno results look here and here. The second link includes a post demonstrating the importance of timing.

[Houdini]

Luke,

Interesting that your Dyno was almost exactly the same as mine except I had a 100% stock exhaust system. I did check my timing and it was set correctly so I would check yours just to make sure. When I turned my boost up to .9 bar I had a peak HP of 158 at the wheels. Okay, but not great. After getting the old turbo out of the car I have my doubts on the potential HP that it can accomplish. Don't get me wrong, I think it's a great litlte turbo and works extremely well in the Elan, but to get some of the numbers I'm seeing with chips and exhaust I get the feeling it's working out of it's effiency range. I still want to take the housings off and do some measurements on trim, A/R, wheel dia etc. to get a better feel for it's potential. I posted earlier that it looks like a 185 HP turbo but I may be wrong, maybe it really can do 200-210 or so. I'd really like to get it on a gas stand and get a compressor map on it so I can be proved wrong, but that test is not likely to happen. So I will take some measurements and try to compare it to a known turbo. This still won't be 100% accurate because the wheel and volute aerodynamics will be slightly different, but it should be in the ball park.

[Houdini]

Well I took the stock turbo apart after posting here this morning and I was pleasantly suprised. Although a direct match wasn't found it did seem to fall between 2 different turbos on the compressor side. I took the larger turbo for comparison and it looks like it could fall into the range of 200 to 215 HP assuming the wheel aero is similar which can't be validated. Maybe 225 is obtainable but it didn't look promising.

[lwalling]

I checked the timing on the car - it's bouncing right around 16 degress BTDC it looks like after jacking up the car slightly to get a view of the crank pulley.

I think we may just be seeing that the car is truely weak, versus stock specifications. It was made in 1991, afterall :). Either that or something is seriously wrong with my 9k mile car. I can't find anything at first (or second) glance other than my slightly damaged intercooler - that doesn't appear to be leaking, it still needs to be replaced (TurboCharger ! Hurry! Make those 'coolers)

The same dyno showed this chart on my Esprit,
http://www.lukewalling.com/espritdynochart_111105.jpg

This is a Mustang Chassis Dyno, supposed to be extremely accurate.

The little car would barely pull 6500pm on the dyno, it was running out of steam. We also had trouble picking up an accurate tach signal on the car, and tried to correlate MPH to RPM, it came out spot on by the gauges on the car anyway. If anyone has a clue there, would love the feedback :) The Esprit, again, no problem..

I really am ticked with the numbers anyway, I want to see them up around 180~ hp at the wheels!

Anyone had their car dyno'd with a chassis dyno ? It looks like everyone else has run on less accurate equipment.

[John_W]

Anyone had their car dyno'd with a chassis dyno ? It looks like everyone else has run on less accurate equipment.

Only Costas, I think, and his car isn't exactly standard.

[Houdini]

Anyone had their car dyno'd with a chassis dyno ?

Mine was and that's where I got the 140 at the wheels at .65 bar and 158 at .9 bar but with stock exhaust. Can't wait to dyno again after the new turbo

[lwalling]

There are several posters on Isuzu forums suggeting 10 degrees BTDC, rather than the factory 16.

Also, what about the richness of the mixture ? can you program that out and bring it back closer to what it should be or should I use a manual means of doing so (pressure regulator) ?

Did you intend the mixture to be so rich, or is this something unique to my situation ?

Thanks.

Hi Luke,

Sorry your number aren't quite as high as might be expected.

Doug mentions timing because its known to be critical to power output - I don't anyone advocates changing it from stock just make sure its precisely set to the specified value.

As to other dyno results look here and here. The second link includes a post demonstrating the importance of timing.

[F1 LOTUS]

I checked the timing on the car - it's bouncing right around 16 degress BTDC it looks like after jacking up the car slightly to get a view of the crank pulley.

You probably did this already?... in order to check the timing the car has to be put into the correct mode by 'shorting' pins on the ECM I believe?

[lwalling]

You probably did this already?... in order to check the timing the car has to be put into the correct mode by 'shorting' pins on the ECM I believe?

No, I didn't short any pins ? I tested the timing though already and it is at 16 degrees BTDC.

Why would I need to short pins on the ECM to test/set the timing ?

[lwalling]

This was mentioned on the Isuzu forum, any possibility ???

"You might want to have ElanScanMan code you another chip....
My guess is that the fuel curve isn't right and killing your power all the way through the band, as evident from the relatively flat HP and torque curves....
Either that or it is coded for a bigger turbo??"

[Candles]

16 Degs BTDC applies only when the ECU is in diagnostic mode, i.e. with the pins shorted. Once the ECU is running, it varies the timing, typically advancing it, even at idle IIRC. That's why you're describing the timing 'bouncing.' In diagnostic mode, it stays rock solid.

http://www.lotuselancentral.com/repair/timing.htm

That should help the power. On my car, it makes a huge difference to everything, even smoothness.

Candles.

[Candles]

Why would I need to short pins on the ECM to test/set the timing ?

Coz that's how they designed it.

[Sy V]

Candles and Brian are 100%. You must put the car into test mode by ALDL shorting before checking/adjusting timing.

[Nige]

Adding to what everyone else has said here. I have very similiar mods on my car to yours (everest chip, 2.25" rather than 2.5" exhaust but that shouldn't make any difference until about 250 BHP) and I have the Dyno figures that show 174 BHP at the wheels which is calculated back to 204 BHP at the crank, this is about what you should be seeing with the mods you have. I too believe your issue is most likely to be timing and as it's easy to do it's worth checking first anyway, but you must put the car in 'field service mode' to set the base timing. I had a poor connection when shorting the pins in the ALDL connector and the timing on my strobe remained bouncing 2-3 degs either side of 16 deg BTDC even with when rotating the CAS the full extent of its travel. See the timing write up here http://lotuselancentral.com/repair/timing.htm

[lwalling]

I varied the timing a bit this evening after reading the info provided (thanks).

The timing was @ roughly 18/20~ degrees BTDC or so, I fiddled with it and didn't notice a significant change in the cars behavior. I left the timing roughly in the middle between 10 and 20 before shutting down for the night and noticed that based on the factory boost gauge the car is no longer producing as much boost.

I might take it back to the dyno shop and do a little fiddling on the dyno and see what produces the best results. The timing changes did not produce a 30~ HP gain though, going by the "ass dyno" anyway, it wasn't to awful far off.

I tell you that is a pain in the ass of a spot to check timing at though! :)

Thanks.

Adding to what everyone else has said here. I have very similiar mods on my car to yours (everest chip, 2.25" rather than 2.5" exhaust but that shouldn't make any difference until about 250 BHP) and I have the Dyno figures that show 174 BHP at the wheels which is calculated back to 204 BHP at the crank, this is about what you should be seeing with the mods you have. I too believe your issue is most likely to be timing and as it's easy to do it's worth checking first anyway, but you must put the car in 'field service mode' to set the base timing. I had a poor connection when shorting the pins in the ALDL connector and the timing on my strobe remained bouncing 2-3 degs either side of 16 deg BTDC even with when rotating the CAS the full extent of its travel. See the timing write up here http://lotuselancentral.com/repair/timing.htm

[Doug]

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 . . .