xhomm02

Hi,

this is a small tuning guide based on my 2 years experience with LPG on EVO X. I am not a tuning guru, so all recomendations are based mostly on my own experience and read theory.

Everything here only concerns VAPORIZED LPG injection. Tuning for liquid LPG id different

1. How it works

- All engine management is controlled by stock ECU. LPG ECU only makes recalibration of the LPG IPW based on LPG temperature and LPG pressure (which varries pretty much, as system I am using does not use LPG pump - which is most common setup). LPG ECU also makes a lot of other work, which is not so important.
- Liquid LPG flows through filters to vaporizers (usually 1, on my car 2 pcs due to high boost and power output), which use engine cooling system to be warmed and produce vaporized LPG.
- This gas then flows through 4 LPG injestors to manifold to each cylinder intake valves

2. Starting tuning

- I tried to avoid using WB - I am lazy to install it, but finally I have found that it IS NOT POSSIBLE to tune the car without it.
- First you have to tune te IPW calibration (in LPG ECU) to be able to maintain idle and cruise LTFT near zero as while using pump gas.

3. Timing
- LPG burns slower than gas at low RPM/load, so you have to add a few degrees in this area (I added 2-5 degrees over 93oct gas). Otherwise you will not get ideal power and your exhaust valves will be worn quickly.
- On the other hand in high load/RPM it burns faster, so you may need to remove a few degrees of timing there to avoid knock. I had to remove 5-10 degrees in 1000-2000RPM in load over 70. Also removed 1-2 degrees near redline.

4. AFR - lambda 1 is achieved at AFR 15.5. This has to be taken into account.

- Cruise: I found that in cruise I get best fuel economy at AFR 16,8-17, whis is achieved with LC lamda emulation. This requires 5deg. timing increase over lamda 1 on pump 93 gas. I use open loop up to 4500 RPM up to 90 load.
- Boost: vaporized gas misses the cooling function of liquid´s, that´s why AFR timing completly differs from liquid fuels.
- Best performance is achieved at AFR 13,2 - 13,5. Unfortunatelly the LPG ECU is not able to hold these narrow limits. I have tuned the engine to have 14-15 AFR while building boost and hold 13-14 AFR once the boost is achieved.

5. Knock: instead of liquid fuel, in this case we cannot fight knock with enrichening the mixture. Richer that 12,5 AFR produces excessive heat and a lot of knock/preignition (cannot say which one of this) and is pretty dangerous. The way that is correct is not to enrich the mixture while knock detected (and I read recommendations of leaning the mixture to cool down the burning process with more fresh sucked causing less cylinder pressure and heat) and retarding timing like usually.

5. Achievments:
- With this setup I can reach 24-25 MPG in cruise (recalculated to pump gas consumption - LPG consumption will always be 20% worse due to different chemical properties)
- With TBE and panel filter only modification I can get 290-300 WTQ/WHP on mustang dyno emulation in VDR. 0-60mph in 4,9 sec. without lounch control.

EDIT: on Evo X MR

I will post pictures of my maps and car setup later.

vik

Zajímavé

Mad_SB

iTrader: (8)

How does LPG injection take to water injection?
If you are un able to get the charge cooling benefits with lpg and are not able to run the best power mix of 13.2:1 it would seem that if H2o injection does not foul the mix characteristics you could pic up a LOT of power by injecting a low volume of straight water.

Minde_Kei

thanks, for the info.

it is project that i have allready 2-3 years in my head

do you use Alternative map for LPG? Did you swithc it manually or using 5v mod with LPG system switch at the same time?

xhomm02

Yes, I have special maps for LPG. I switch it manually, as I run all the time LPG and therefore have gas map only for the purpouse that I run out of LPG with no LPG filling station near. Then I reload the pump gas map.

xhomm02

And this is my timing map.

oreficeraffaele

What is the brand name of this plant? On my EVO I have a ICOM system with eight injectors per cylinder and the map completely customized for LPG. However despite the stroker kit, I can get a good yield but always with a consumption of 6 liters per km. What unit did you use? I used the original ECU. The map that I had to do was very complex.
What is the pump you used?

vermilion

Hi Guys. In 2 weeks, I'll apply Prins brand LPG kit on my '11 Evo X. I'm guessing they will apply VSI-LPG type which uses Vaporized LPG.

The guy that will apply the kit is a very experienced person who did lots of Porches, S5's and M3's. He said he will spend 4-5 days minimum to have a perfect setup. Do you have any suggestions for me to pass him? As far as I know, this will be the first Evo for him. He said he will use "Brown Prins Injectors" which can take 110 HP for each cylinder. Also, he told me to buy and apply anything I want first, like K&N air filter, Blow-off, ECU remap (which gives %10-15 HP over stock) then bring him the car, so he can do the settings on the final setup of the car.

You're mentioning about %20 increase. In my previous car, the increase was around %10. Is it because you aimed to keep the performance nearly at the same level? I mean, 4.9 sec is pretty good. Most of the people couldn't get this on stock ecu and gas. Is it possible if you can write down the exact figures that you get on highway? Were you using Cruise Control when you get around 10l/100km ? Also, what is your in city figures?

Also, I was wondering if it is possible to have 2 separate tunes for both Normal and Sport Modes. I'm wondering if we can change the time when turbo starts working and reduce the HP to have a better fuel consumption while we are cruising on Normal mod? This way, in Sport mod, I'll benefit the %10-15 HP increase of ECU tuning and more power. Do you think this is possible? Having 2 different maps on activated by Normal and Sport mode?

xhomm02

Hello,

Yes - do all your mods (upgrades) before installing LPG.

But I am afraid of one thing you did not mention - really good tuning means you tune stock petrol ECU hand in hand with tuning LPG ECU. So if you want to get best performace/best consumption, the tuner needs to play with both in cooperation. Because LPG has different properties the ECU needs to be tuned for it (of course it is not best tuned for petrol then)

I completly remapped the ECU (most the timing advance map-you can see a picture above, completly the MIVEC maps, AFR map, reactive selenoind+target load map and minor changes to others), so that now it work perfectly on LPG but if I want to use petrol for longer driving (not only to get to petrol station), I would have to flash petrol map back. Having 2 different tunes in ECU and being able to switch between them is the best way - search Tephra MOD X thread on forum, there was written a lot about this. I do not use this as my tuning software is not capable of it.

I also use WB to keep my AFR in cruise at lamda 1.1 which means AFR 17.1 on LPG.

When using LPG, there is always at least 20% increase in consumption over petrol (LPG has less energy than petrol in a unit). So if your display shows 10l/100km it means it takes cca 12l LPG/100km.

My consumption is about ( litres LPG / 100km ):
highway 12-13
out of city family style driving 12
city 14-15
aggresive driving - depends on how aggressive

I hope it helps.

leba

Hi xhomm02,

I do not really get your point about the timing, you said you need to add timing in low load/rpm but then talking about "I had to remove 5-10 degrees in 1000-2000RPM in load over 70"..
Is really that drastic change needed by the way? I do not believe the companies doing the LPG rebuilds modifies your fuel maps/requires using 2 maps... even at turbo motors.
I got 4g63, that is different motor, but I was just curious about your previous 93 map to see the difference in related/touched timing map areas..

Thanks.

xhomm02

Hi, there is no contradiction - you usually do not drive under 2000 rpm and if so, it is in low load (UNDER 70). You should increase timing in the BELOW load 60 area.

But in RPM below 2000 and load ABOVE 70 I experienced persisting high knock count, that´s why I had to decrease timing a lot. However as I sad, this is not area where you should get often.

You are right, workshops rebuilding to LPG usually do not do any changes to timing, because they would have to have possibility to reprogramm stock ECU - and tuning the timing map on dyno for every rebuilt engine would be very costly to customer.
The rarely use additional timing computer (but these "computers" just increase timing by adding constant degrees of timing to the whole timing map while the engine runs on LPG, which is wrong, because LPG burns much slower in low RPM/LOAD, but faster in high RPM/LOAD than petrol)

So if you do not do any changes to timing, the engine will run, but not with ideal efficiency and you may encounter high knock in some cases.

By the way - what kind of LPG system do you have and how are you satisfied with that?

leba

Hey xhomm02, thaks for valuable info!
I am thinking of one Czech systems available here, think its called Magic. I got E85 and N98 maps to switch in Tephra mod, but seems like I will have to give one of them to the LPG system to be effective as much as possible.
I did send you PM so we could discuss more details about local LPG suppliers here..
I will post more here when having "real" data (even on 4G63).
Thanks again.
Cheers

morgeesplease

Im loving all the different Evo around the world drinking down the good fuels like LPG!!
Im in Australia and have a Evo6 with Evo9mivec and 2.3L. Once the engine is back in ill be waking up the ICOM liquid injection system to see what beast i have made..
GL on yours.

Eric.
Evolutionoz.net