A Question for GAD tuning

[MBDevotee]

Hi,

I see on your website that you do a tune for the 500 - 5.0V8 292hp engine which gives an extra 20hp (ish).

I am looking to buy either an ML500 or 350 which will run on LPG.

Given the very different burn characteristics of LPG (Higher Octane (around 112) but lower calorific value) - do you do (or rather could you do) a remap to allow for the different fuel type (allowing for the fact it starts on petrol of course) to minimise the standard 10-15% drop in economy and performance??

Of course the other thing to know is what that sort of remap would cost, as I'm guessing it wouldn't come cheap!

Thanks

 

[GAD Tuning LTD]

Wow now thats a tricky one!!! What i will do is put this to the technical director and see what we can come up with!

Many thanks and a happy new year to you!

Regards

Anthony @ GAD

 

[Devonian]

A very interesting question, I look forward to GAD's reply. I don't really see how the economy drop could eradicated due to the lower calorific value of LPG but it might be improved which considering the amount of LPG vehicles aroound could prove to be an opportunity

 

[L John]

Not sure how an LPG system works, can you switch to petrol at any time whilst driving?
If so then why not get GAD to tune for petrol and use that when you want performance?

I really can't see the point in using the LPG when you want to use full throttle, it's not like the car is at full throttle for long on the road.
Would it be possible to set it up, to switch over to petrol when using 75% or more throttle, or is it not able to switch over whilst under power.

 

[MBDevotee]

Some (not all) of the performance drop (and it's minimal) is that LPG burns differently to petrol.

If they can remap it to advance the timing enough to compensate, I think the performance drop would be immeasurable (I don't care about that really - the ML500 is certainly fast enough) but more importantly, I think that altering the timing and fuelling properly, would probably eliminate the 10-15% economy drop that goes with a conversion...


So if you could keep the performance the same - AND minimise the economy drop, and the remap was cheap enough, it would become a total no-brainer for anyone with an LPG conversion - and believe me, there are a lot of us out there!

 

[MBDevotee]

Wow now thats a tricky one!!! What i will do is put this to the technical director and see what we can come up with!

Many thanks and a happy new year to you!

Regards

Anthony @ GAD

And to you....

And if when I get the car, you fancy doing me a freebie to test out the LPG / maps etc I'm more than happy lol

 

[Devonian]

Would it be possible to set it up, to switch over to petrol when using 75% or more throttle, or is it not able to switch over whilst under power.

Yes, with modern multipoint injection systems you have total control, you can set it up pretty much how you like, to automatically switch over to petrol at a certain rpm or under heavy acceleration, or you can choose it inject a small amount of petrol along with the LPG Etc

 

[MBDevotee]

Not sure how an LPG system works, can you switch to petrol at any time whilst driving?
If so then why not get GAD to tune for petrol and use that when you want performance?

I really can't see the point in using the LPG when you want to use full throttle, it's not like the car is at full throttle for long on the road.
Would it be possible to set it up, to switch over to petrol when using 75% or more throttle, or is it not able to switch over whilst under power.

It's not really the drop in performance on LPG that I care about - it's too minimal to measure really - it's the fact that the engine is optomised for petrol ordinarily, so 99% of the time you are running on one fuel in an engine optimised for another.

If you could optimise the tune for the LPG (whilst making sure that it can still run ok on petrol) then the whole thing should run better....

No point switching to petrol at the top end of the rev range - if you need to do that, there is something wrong with your LPG conversion....