Hemi

[Hemi123]

I know that the 5.7 Hemi is not listed on the lists that I have looked at by BRC and Prins in regards to suffering from valve seat recession, therefore not requiring the fitting of a system to provide upper cylinder lubrication.

However I was wondering what the long term effects of running one on LPG are and whether the engine/valves wear faster than if it had just been run on petrol over that time.

[woody]

almost impossible to answer i think, i have never heard of a Hemi failing...at all.I have done more than most and never fitted a valve care system.


woody

[billynoband]

You should take Woody's advice but Badger on here fitted lpg to his Chrysler Hemi in 2006 and reported it on here so he may still have the car. If you search for his user name you will see the post. I know he still frequents the V8 user forum in the lpg section, hav'nt seen him on here for a while though.

[Yank Boy]

Woody did my 300C Hemi back in 2010 it's done 52000 miles on LPG and it's sweet as a nut.

[Hemi123]

Is it normal to be able to tell when the system switches the engine from petrol to LPG?

[Gilbertd]

The light on the switch stops flashing and the engine may get quieter and smoother. If it doesn't, it may need a service.

[Hemi123]

The led on the switch is red when it is running on petrol, than turns yellow when it is switching between petrol and lpg, than green when it is running on lpg.

[herbertpug]

I'm considering getting a 300c SRT8 as my next daily LPG car. (Or a Mercedes R-Class as I need to fit 3 baby seats in the back occasionally)
How is the LPG working?
What system and how big a tank can fit in the spare wheel well??
I often do 300 miles a day... Could I do this on LPG alone? (65mph on motorway so I assume around 25-30mpg?)
Please advise if you can. Thx.

[Yank Boy]

I have a 56L tank in the spare wheel well and a 100L behind the back seats and still have a usable boot. I can get 119L in from empty and that will get me between 350 and 400miles depending on type of driving.
But your dreaming if you think you are going to get 25-30mpg out of a 5.7 Hemi and if you just go for the one tank in the wheel well you will have a very short range.

[herbertpug]

thanks for this so the tank behind the back seats takes up space that could be used by prams and buggies? how much of your normal traveling is done urban as opposed to 55 mph? does the engine sound great?

[Yank Boy]

It's a massive boot to begin with so there's still loads of room, we can still fit a pram in the back.
My driving is probably 60% urban 40% motorway usually cruise at 85/90 on motorway.
It's quite subtly muted until you give it some right foot. I don't drive for max fuel economy you don't buy a V8 for that do you.
And thanks to the technology of IPhone I have tracked my MPG over the last 20,000miles and I have averaged 16.5MPG I'm paying £0.66 per litre so I reckon that's about equivalent to getting 32MPG in an oil burning clatterbox.

[dannyf]

the srt8 engine i have has a lpg system on it and has caused no problems
the ls3 had wanted new valve seats after a few years and a tidy up on the head but that was no biggie

on my 300C Srt8 the engine Cut's down to a V4 when being used around town and all 8 come into play when you push it a bit

[herbertpug]

How do you cut it down to V4? Is that a factory config or 3rd party mod?
If it's only on the newer models, can it be done retrospectively on older models?
Thx.

[rossko]

No, its heavy engineering
http://www.autoinc.org/archives/2009/oc ... chtips.htm

[herbertpug]

I've been looking around and the MDS only appears on the 5.7l and not the SRT 6.1l Engine.
http://www.iframac.mu/BROCHURES/Chrysle ... 20300C.PDF
I can't find it on the SRT anywhere.
Also, if it DID cut down to V4, and the LPG is direct injection, how does the LPG ECU know?
Any tips welcome thanks.

[Gilbertd]

Also, if it DID cut down to V4, and the LPG is direct injection, how does the LPG ECU know?

It doesn't need to. The MDS system shuts down 4 of the 8 petrol injectors so the corresponding LPG injectors won't see a pulse so won't do anything. I suspect the LPG controller will get offended and flag up what it sees as an error but I'm sure there would be a way round it.

[Yank Boy]

Mine is the 5.7 with MDS and in the real world it's worth nothing as an economy aid.
You don't by a V8 to feather the throttle for an extra MPG do you.