Auto-LPG Conversion Thread

[ghosthunter]

I've decided to have my 1997 Honda City Exi converted, but I'm still deciding between an SGI kit or a Venturi/Mixer type. I can afford the SGI kit, I'm just wondering whether the price difference is worth it. I understand that SGI provides better power and FC.

It can provide a better potential for a better mix of power & FC. But you will need to spend some money to achieve that potential. Otherwise, if maximizing your engine's performance is not in your agenda, simply opting for the venturi-mixer kit would be cheaper which would mean you would reach your ROI in a few months earlier.

Are there any other advantages provided by the SGI kit?

Eliminates the potential of backfire in the intake manifold.
Minimizes the "leak-back" smell of LPG from the intake manifold.
Eliminates the venturi constriction "donut" (for improved air flow as compared to with venturi).
Less maintenance of the air-filter (venturi requires periodic cleaning of the air filter).

[chinacrisis]

wow, thanks for the quick reply ghosthunter. I have some further questions:

I note that you said that a SGI kit "Minimizes the "leak-back" smell of LPG from the intake manifold." Does this mean that may smell pa rin? Does this mean na sa venturi, the smell is worse? Is not there a way to eliminate the leak altogether, or is leaking a risk that comes with any LPG system?

In terms of driving routine, does SGI change anything? For example, if I'm on a venturi system, i'll have to remember to do this and that to prevent, say overheating, but in an SGI system, these things are automated.

[ghosthunter]

I note that you said that a SGI kit "Minimizes the "leak-back" smell of LPG from the intake manifold." Does this mean that may smell pa rin? Does this mean na sa venturi, the smell is worse? Is not there a way to eliminate the leak altogether, or is leaking a risk that comes with any LPG system?

SGI kits will still have some degree of "leak-back" but very minimal depending on the distance of the injectors from the cylinder intakes. Also the angle of the intake manifold tubing will play a part if there is any LPG leakback, SGI or venturi system.

Generally there is no risk from the small amount LPG back-leaking from your intake manifold. In my years of using my system, I don't smell LPG under my hood whenever I poke my nose in the engine bay to check something.

In terms of driving routine, does SGI change anything? For example, if I'm on a venturi system, i'll have to remember to do this and that to prevent, say overheating, but in an SGI system, these things are automated.

Nope... the only difference is when you start the car. SGI systems are automated to switch from gasoline to LPG after a short warm up period. Venturi systems generally are manually switched from gasoline to LPG but there are some venturi systems that are also switch automatically but I am not sure which installer has them.

[bigMIKE]

I saw it before it was installed, but not since then. Why do you ask sir Mike? Are you starting to install them as well?

Not actually, with an oxygen sensor installed It would have been better to install an SGI system already....

[niky]

Leak-back is something that can occur whatever fuel you use if your car is tuned too rich and dumps fuel when you close the throttle. Heck, if you own an old carburated gasoline engine, you'll be able to smell this... But with the design of most stock EFI systems, with long runners between the throttle and the injectors, leak-back is almost non-existent... and since SGI injectors are often placed as close as possible to the mounting points of the stock gasoline injectors, it's a non-issue.

It's an issue if you have an open-loop Venturi Mixer kit on an EFI engine equipped with a MAF (mass airflow sensor) and your installer tunes it too rich. You can have the occassional backfire (note, this is only when the installer tunes it too rich) which will roast the sensor. For these engines, an SGI system is definitely recommended. For cars with MAP sensors, like Honda Civics, it's not an issue, but still... if you can stump up the extra for an SGI kit, all the better.

[chinacrisis]

wow, thank you for the informative replies sir ghosthunter and niky. I guess I have to limit my questions on the kits that greenfuel installs, since that is what I'm considering.

Can anyone elaborate on what features are present in the greenfuel SGI kits but are not present in their venturi kits? especially, what tasks are automated in their SGI kits but not in their venturi kits?

Also, my wife is affected by the negative rumors re: LPG conversion. She has threatened not to ride in my car if I have it converted. Though this means less work for me (no more hatid/sundo ), to allay her fears I told her that I can turn off the LPG kit when she's aboard, to eliminate the any chance of any LPG leakage when she's aboard. Is this correct? TIA

[ghosthunter]

Can anyone elaborate on what features are present in the greenfuel SGI kits but are not present in their venturi kits? especially, what tasks are automated in their SGI kits but not in their venturi kits?

The main task that is available in SGI kits and not in venturi kits is the start up sequence. The engine starts on gasoline (because engines start easier on gasoline) then it switches to LPG once you rev the engine to 2000rpm. It also switches to gasoline a few cycles every predetermined time to "lubricate" the injectors.

Also, my wife is affected by the negative rumors re: LPG conversion. She has threatened not to ride in my car if I have it converted. Though this means less work for me (no more hatid/sundo ), to allay her fears I told her that I can turn off the LPG kit when she's aboard, to eliminate the any chance of any LPG leakage when she's aboard. Is this correct? TIA

er.... it depends. The system is still "there" and she would be suspicious of it even if it's off (although you can turn in on with her in your car as long as the LED "guage" is installed out of sight from the passenger side of the car). Most of the time, the source of leak is from the multi-valve part of the tank. The good part is it's "sealed" inside a housing which is designed to vent any leaked LPG down and out the car and it would simply dissipate in the environment. In any case, LPG will not reach the cabin unless you remove the clear cover of the multi-valve housing.

Maybe she should read this thread? ... It seems to answer 99.99% of what people would ask including safety.

[chuaed]

my wife is affected by the negative rumors re: LPG conversion. She has threatened not to ride in my car if I have it converted. Though this means less work for me (no more hatid/sundo ), TIA

that means more time for yourself (gimmik)... what are you waiting for? pakabit mo na...

[paolorenzo]

Sabihin mo... "Kung ayaw mo, eh di iba na lang isasakay ko." :naughty2:

Kidding aside, I had my share of explaining. To help keep with everybody's peace of mind (including my own), I installed an LPG alarm. Sa awa ng Diyos hindi naman tumutunog (pero ayos naman sya kasi meron diagnostic chirp).

[abetg]

SGI kits will still have some degree of "leak-back" but very minimal depending on the distance of the injectors from the cylinder intakes. Also the angle of the intake manifold tubing will play a part if there is any LPG leakback, SGI or venturi system.

Generally there is no risk from the small amount LPG back-leaking from your intake manifold. In my years of using my system, I don't smell LPG under my hood whenever I poke my nose in the engine bay to check something.




Nope... the only difference is when you start the car. SGI systems are automated to switch from gasoline to LPG after a short warm up period. Venturi systems generally are manually switched from gasoline to LPG but there are some venturi systems that are also switch automatically but I am not sure which installer has them.

mine is an eroom kit with an auto switch setting and according to its manual and the installer, the system automatically operates from gasoline to lpg upon reaching the operating temperature and (at least) 2k rpm. haven't tried it yet though.

btw GH, i was not able to try removing the air filter (as per your suggestion) as the problem (difficulty in switching from lpg to gasoline whereas the engine dies out) was already addressed by Mr. David Do of eroom. the culprit was traced to a malfunctioning fuel cut-off device which was immediately replaced by Mr. Do himself. now everything's working fine and to add a note, my FC is at an average of 9kmpl compared to 10kmpl on petrol (city driving).

[reginald07]

Now i'm confused...

a few pages back, sir ghosthunter said something like

"In the end, it will be operating exactly like the venturi-mixer auto-lpg kit but with a more expensive installation bill."

when i asked about installing an SGI kit on a corolla w/o an O2 sensor...
thus, i had a (possibly erroneous) conclusing that my car's performance would be more or less the same if i go for SGI or venturi-mixer type.. which made me rethink on installing an SGI kit.

but reading his and niky's replies to chinacrisis' inquiries is swaying me back towards SGI. haaay....

eto na lang tanong ko...

If ROI and price isn't a question... peformance-wise...

SGI or venturi-mixer type?

[niky]

Just ask my wife. She can't tell at all when the car is on LPG or not. Not by sound, not by smell, not by the way it runs. An SGI system is completely transparent, completely odorless and completely invisible if you upgrade to a toroidal tank like I did. Just do it. Run it for two weeks. And then ask your wife... puwede ba, hon? If she says no, then drop the bomb on her that she's been riding in an LPG car all this time...

*BigMike: So there's a pre-determined "pulse" of gasoline every few minutes? Hmmm... is there a control in the computer to alter this? Ghosthunter and I were talking last night about enriching the charge with a bit of gasoline at over 6000 rpms to remove the power dip at 6500 rpm. If you remember the dyno, Mike, Ferman had it almost exactly the same as gasoline on LPG except at redline. Was thinking letting the gas injectors go on a crack at redline would cure this? (But it's not a big deal...)

[ghosthunter]

eto na lang tanong ko...

If ROI and price isn't a question... peformance-wise...

SGI or venturi-mixer type?

A SGI system has a bigger performance POTENTIAL. Of course, if your engine is totally stock, don't expect any real HP gains simply by tweaking the LPG system.

You have to consider Niky is on the extreme side of the "motoring" public where performance is a priority and his mods on his car shows it (along with the hefty bill at Speedlab). For the majority, as long as the engine runs well, no power loss, the system is dependable in the long run and saves money because of the cheaper price of fuel (lpg), that would be good enough.

[aamd]

Is there a way to monitor the performance of carburator venturi kit if it is running on lean or rich mixture?

As i understand, one way is to physically check the spark plug of the engine.

Is there another way?

[ghosthunter]

Is there a way to monitor the performance of carburator venturi kit if it is running on lean or rich mixture?

As i understand, one way is to physically check the spark plug of the engine.

Is there another way?

Well, there is the Oxygen sensor and meter retrofit. You can find these being sold on some online autoshops. $200+ prices though. If your car is alreadt equipped with an oxygen sensor, you can try looking for someone just selling the meter. I would advise you to get the self-heated oxygen sensor since still will give you a more stable reading. Single wire O2 sensors tend to jump around too much especially if the radiator fan blows air on it.

Or simply do the sniff test after you have warmed up your engine. If your engine is running correct, the exhaust should only smell lightly of LPG. If the scent is strong, you might need to clean the air filter or adjust the venturi system.

[niky]

A SGI system has a bigger performance POTENTIAL. Of course, if your engine is totally stock, don't expect any real HP gains simply by tweaking the LPG system.

You have to consider Niky is on the extreme side of the "motoring" public where performance is a priority and his mods on his car shows it (along with the hefty bill at Speedlab). For the majority, as long as the engine runs well, no power loss, the system is dependable in the long run and saves money because of the cheaper price of fuel (lpg), that would be good enough.

The difference is... with SGI, your performance loss will be much smaller than with a Venturi. Typically, untuned, an SGI-LPG system will run great on a modern engine, with more hp at low rpms and a slight loss at high rpms... as compared to a Venturi kit which will lose power due to the extra restriction.

Of course, yes, I'm an extreme case... my engine is already tuned with massive amounts of timing advance, which LPG absolutely loves, and it has performance parts on it.

The purpose of the tuning session was to prove the viability of LPG for performance cars... but fact is, most modern cars will run an SGI system with no loss of power at low-to-medium rpms. (Referring to Ghosthunter's post a few dozen pages back about acceleration testing on the Camry... no difference in peak acceleration in low gears). What we're showing here is that whatever power difference remains can be minimized through proper tuning.

For me, the ease of use, peace of mind, and the smoothness of operation of the SGI kit are worth the premium over the Venturi-mixer.

Oh, and the fact that it doesn't negate any of the gains of my xxx pesos worth of mods doesn't hurt, either...

[rpxhost]

Somebody has to write an FAQ book on LPG based on this thread, now!

It's not convenient going through all the discussions and no way of knowing if the info has been updated.

An FAQ will have topic categories, so one can easily find the info.

If Ghost Hunter will not do it, I will. That's a warning.

[rpxhost]

As for my previous post, here's the new info

Toyota Corolla 1.6GLi A/T EFI

The Lovato was SGI so out of price range.

They offered the following:

First Autogas (retailer of PTT Gasoline Stations)
1. Hedef
2. Voltran
3. FEMA

all from Turkey at P17T each cash price (not SGI)

While JW
offers
1. NAIADSS at P28T cash price (not SGI)



I heard from the grapevine
1. Hedef's switches easily breaks down
2. Voltran's diagphrams easily breaks down
3. Both brands have inaccurate meter readings due to floater design issues (length of floater?)
4. FEMA has lesser breakdown issues on both switches and diagphrams (some technicians havent encountered any such defects since installations a few months ago)
5. All three brands are from Turkey
6. I have no source of info for NAIADSS although their sales staff at JW assures customers they have best technicians for tuning the LPG.


Now some questions:
1. Is it really worth going for SGI for an old car?
2. Any experience regarding these brands above? or other brands?
3. What do you really mean by "gasoline feel" for LPG driving?
4. What is it that one should look at to know the LPG needs more power tuning?
5. Why is it that the techs seem to be reluctant to give more power mix?
6. Is there any FAQ out there? some blog or website of Philippine LPG experience?

thanks.

[rpxhost]

Hmm.. maybe the density of the LPG are not the same. This LPG station's liquid is not that compressed that why you achieved more volume when it was compressed into your tank. .. meaning you are paying more LPG with extra "air" added.

Just a chemistry random thought..

[ghosthunter]

Somebody has to write an FAQ book on LPG based on this thread, now!

You mean this book?

It's not convenient going through all the discussions and no way of knowing if the info has been updated.

An FAQ will have topic categories, so one can easily find the info.

For general questions, you can refer here:
http://www.greenfuel.com.ph/faqs.html