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EggyD 06-22-2011 07:13 PM

D15B with Neptune RTP
 
Hey guys I got my Neptune setup about 2 weeks ago and am on my second tank. The first LEAN burn attempt was 38mpg. Not as good as Ive seen people getting. my 2nd tank looks to getting a lot better. Im at 240 miles and the gas gauge is at almost half tank. Is there someone here that can read my tune and give me some pointers? and also what should i change? like Disable Closed Loop, fan control in gauge at 180 above 50mph ext.... any thoughts are greatly appreciated. Thanks

EggyD 07-31-2011 04:07 PM

It's been a while know and still not very happy with the lean burn tune. Best attempt is 43 mpg and I know there's people getting way better results. Any tips would help out slot. Thanks

Tygen1 07-31-2011 09:27 PM

What AFR are you running? How fast do you travel? Do you have an instantanious MPG display, if so what are your typical readings? What other mods do you have to your car? I assume you are running a wideband, which one?
Give some more details and I will help where I can.

I'm running around a 17:1 AFR, driving 50-55mph with aeromods and very LRR tires. My instant readings are in the mid seventies with this set up.

EggyD 07-31-2011 09:42 PM

I have a innovate lc-1 running at 19.5 afr ( no b.s. ) while cursing 45-55. I have a jdm d15 single stage vtec with a Skunk2 intake manifold tubular header and 2.5 exhaust. Lowered on blox coil over sleeves and agx shocks. No ac no ps other than that it's stock. And of corse the Neptune rtp. I don't have a mpg gauge although that's on the list when money allows.

Thanks for the help.

Tygen1 07-31-2011 10:11 PM

Don't worry, I don't believe you are trying to trick me on the AFR.
One thing you gotta consider with running lean is that you need to reduce your load. Big wings, wide sticky tires and the like will have a large negative impact. The more power you need to make to propell your car down the road, then the more fuel you need. That's why I can do so good at only a 17:1 AFR.
Even though I see mid seventies while cruising, I can average just above 50mpg on my regular commute, so you also need to consider the way your drive, the route you drive, etc...

The key ingrediant will be the Instant MPG Gauge. Without it, you will never get your tune right for best mpg while lean. Right now you are just guessing at all of your parameters and they can not even be educated guesses because there is not much of a knowlege base for running this lean. I'd suggest you get an MPGuino imediatly, back down on your AFR and focus on learning how to get a more convervative AFR. You are more likely to suceed this way and learn how to make a tune that works will with lean AFR's.
If your able to tweek your injector pulse widths and timing on the fly, you can just monitor an instant mpg reading and you will know exactly what parameters are needed.

Hope this helps!

Tygen1 07-31-2011 10:13 PM

Oh yea, I have to add that at 45mph, I'm at 16.5:1 and getting high seventies or low eighties and at 35mph, I'm at 16:1 AFR and getting low nineties. Leaner isn't always better, you really need to expirement and think outside of the box.

EggyD 07-31-2011 10:30 PM

Great point I'll report back after I get the mpgunio.

mwebb 07-31-2011 10:54 PM

exhaust pipe diameter is too large
 
assuming 3000 rpm as approximate upper ceiling of cruise , your exhaust pipe diameter is over 200% too large ,
and it does matter
begin here Autolounge.net | Calculators | Exhaust Pipe Sizing

then
read this thread http://ecomodder.com/forum/showthrea...mpg-12247.html all of it .
***************
the MPGuino will help immensely as well


Tygen1 08-01-2011 01:03 PM

I wouldn't split hairs on exahust pipe size. While I'm sure it could be optimized for FE, I don't expect that to be the need in this case. I have an oversized exhaust pipe as well. I like to use my car for more than just good FE. Even when I go drag racing, I am still getting great FE :) I want my cake, with frosting and I want to eat it too! Lean Burn is the frosting :D

EggyD 08-01-2011 05:54 PM

Yeah thanks for the info guys will see what my instant mpg is when get my MPGuino. I'll be able to tune it better from there. Where are y'all mounting it at? I seen a pretty slick setup under and behind the tack. Dose any one know who did that?

oil pan 4 08-01-2011 07:15 PM

How lean can we go before we start to burn valves?

EggyD 08-01-2011 07:44 PM

Well there's a guy on d-series.org with a del sol that's getting over 70 mpg and his tune is over 22 afr with no ill effect. I figured I was safe at 19 with timing advanced to 45 degrees. So fare I've gotten over 2000 miles on this setup and all is good. (knock on wood)

mwebb 08-03-2011 01:17 AM

lean condition results in cooler combustion temps
 
Quote:

Originally Posted by oil pan 4 (Post 253547)
How lean can we go before we start to burn valves?

slightly lean is the problem
very lean results in reduced combustion temps

look at a 5 gas graph for nox , nox forms at high combustion temps
look where the peak for nox is .

mwebb 08-03-2011 01:21 AM

velocity should be no more than 300 fps at
 
Quote:

Originally Posted by Tygen1 (Post 253467)
I wouldn't split hairs on exahust pipe size. While I'm sure it could be optimized for FE, I don't expect that to be the need in this case. I have an oversized exhaust pipe as well. I like to use my car for more than just good FE. Even when I go drag racing, I am still getting great FE :) I want my cake, with frosting and I want to eat it too! Lean Burn is the frosting :D

the rpm you want to optimize performance at
there is only one correct answer

you get to choose - but a gain at one rpm is going to be a
UN gain at the other end of the spectrum

oil pan 4 08-03-2011 09:49 AM

What I have read is 13.2:1 produces the most torque and "highest" EGT's.
But I don't know if that is highest EGTs of all A/F ratios or the highest you get using normal ratios such as 12:1 through 15:1.

I googles searced for quite a while last night and could not find a magic number for the exhaust valve burning air:fuel.
I have burned exhaust valves before I had a car where the IAT sensor was reading 300'F on a normal 70'F day, caused it a nasty lean condition and burned the valves on every cylinder.
Never thought to look for peak NOx to find the highest EGT mixture. I bet that will work.
If I find anything I will post it here. Burning out your exhaust valves to save gas isn't going to save us any money.

An expensive alternative could be to get Sodium core inconel 625 exhaust valves. They are burn proof. I know you can get them for pretty much any chevy V8 gas engine ever made, not sure about getting them for 4 cylinders.

oil pan 4 08-03-2011 02:21 PM

Computerized Engine Controls - Google Books
What air fuel ratio burns valves?
What air fuel ratio causes the most NOx to form?
Looks like just short of 16:1 is your peak for NOx production and likely the peak for combustion flame temperature.
But once you pass 16:1 NOx levels start to drop quickly. 16.5:1 looks about as NOx-ious as 14.7:1.

Tygen1 08-04-2011 03:11 AM

Oil Pan, we are only use these lean conditions under light loads. In your case, you were accelerating under heavy loads while lean, that's why you burned valves.
At some point, I would like to put a EGT gauge in my car to confirm a drop in combustion tempature.

oil pan 4 08-04-2011 07:08 PM

Yes my car was running lean all the time.
You can score a new EGT off ebay for cheap like I did. Or get a used one real cheap if you want to get creative.

mwebb 08-05-2011 12:36 AM

retarded ign timing
 
..."I have burned exhaust valves before I had a car where the IAT sensor was reading 300'F on a normal 70'F day, caused it a nasty lean condition and burned the valves on every cylinder."...

FALSEly hi IAT values will cause
retarded Ignition timing
which will change the timing of Peak Combustion Pressure to
After 14 degrees atdc ...
so part of the charge burns in the exhaust
not in the combustion chamber

contributing to
burnt exhaust valves

oil pan 4 08-05-2011 06:16 AM

The car had a mechanical ignition system timing with mechanical and vacuum advances.

EggyD 08-05-2011 06:44 PM

Thanks for all the info guys. But ahh could we happen to keep this on topic?

EggyD 10-26-2011 02:46 AM

Ok I'm back and have the mpguino calibrated and reading dead on. Tygen1 is there any way I could get your map to take a look at it?

Tygen1 10-26-2011 09:47 PM

Don't have a map. I adjust it on the fly. Every combo will be diferent. To give you some idea, I run about a 17/1 afr at anything less than 50 LOD. You can be more aggressive than that, but it should be a good place to start.

EggyD 10-27-2011 03:44 AM

Ok what was your timing set at? Or did you just adjust the fuel trim?


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