how many degrees retard per pound of boost?

[thechuckster]

oldcorollas: hi stewart! i think it's for petrol only - am going thru the MS site to see what they based their assumptions on.

[oldcorollas]

fwiw, when my mate turbos his ford 4.1L (with up to a bar boost edit: ON LPG) he used the stock dizzy (mechanical i think?) and a...
"HKS Spark Retarder" which retards an adjustable amount over a certain amount of boost...

i wish i could find one of them here it seems to work very well !!.. does basically all you need for the extra load, and doesn't affect the timing elsewhere... but i can never remember what his timing figures are

[thechuckster]

it's all very easy for me now - i have MsnS extra doing spark control so i can map in whatever boost-retard i want...

i cant find the original references for the msefi spark spreadsheet. There was a link to this short article about cylinder pressure and spark advance.

[BrianRA23]

The bigger the balance line the better - I thought it was bigger. The unfortunate thing is that it is illegal to modify (or open) the converter, but if you could it will further reduce the lag in the movement of the disphragm. I used a larger line and then clamped it down on small barb on the back of the converter. Others have put a larger barb on the back, but there is the small risk of a big fine.

On my blow through setup there was a flat spot when the system went from no boost to boost (making it painful in carparks). I had thought with better positioning of the balance line this might have been fixed. Otherwise I was happy with the configuration

If you have already run booost into it then either blow or suck on one of the hoses to make sure it is not damaged.

[love ke70]

and if it is damaged what will i expect?
i dont think its seen much boost, ive dollied it around the backyard to move it, lucky to get beyond idle
and ive revved it to about 2000 slowly turning the throttle, but ive never had the throttle open enough to make boost i dont think.

so suck and blow on the hose i put into the convertor, and if its fuggored it wont move. but if its good i will hear it move?
are you saying the less hose distance to the convertor the better?
cheers, andrew

[BrianRA23]

If it is no good air will escape. You should hear it move back and forth as you suck and blow.

In the previous config it would have gone really lean and died as soon as the system tried to boost.

Another good thing about LPG is that if you loose your coolant the converter will freeze and the engine will die - all before the engine gets to seize

Hose length and size is difficult to determine since you want to maintain a good mixture across the range of air flow through the system. The trick is to get the diaphragm in the right position all the time. Even if you could get the right relationship the converter response is not linear anyway so either you do lots of modelling or have a compromise.

[30psi 4agte]

fwiw, when my mate turbos his ford 4.1L (with up to a bar boost edit: ON LPG) he used the stock dizzy (mechanical i think?) and a...
"HKS Spark Retarder" which retards an adjustable amount over a certain amount of boost...

i wish i could find one of them here it seems to work very well !!.. does basically all you need for the extra load, and doesn't affect the timing elsewhere... but i can never remember what his timing figures are

Those figures i quoted are just rough but i dont see it making much of a diff between LPG and FUEL apart from the fact that you may retard slightly less with lpg due to its higher octane.

I feel its just one of them things that is just a rough guide to set up a base map. In the end it is the dyno and the road where you will really be able to set it up correctly as ALL engines will respond differently. Obviously the more you are able to run with out detonation is USUALLY the better but not always.

On the road with my car i initally set up an ignition map and was running 32 deg on full boost (25psi at the time) with no detonation. When i put my car on the dyno we took some timing out (down to 25-28deg) as i had planned turning boost upto 30. Once the fuel side of things was set up ok we then put timing back in bit by bit but found that at 32 deg @ 30 psi there was no more power or torque than if i was running 28 deg at this boost.
Hence i dont run more timing than i need and feel timing should really be setup on a dyno or atleast the road so you can get a feel for things.


P.s those spark retard gizmos you are talking about are great my mate uses one one his 180B and swears by it!

P.P.s I think all dizzyz from the XF (mabe earlier XE ESP?) have been electronic.

[oldcorollas]

PPS, yup, they were, but he grabbed dizzy from earlier car, since he ripped out the ford ECU and put in a megasquirt when it was dual fuel

what is the model your mate has??
i've been searching around and can't find the HKS one here anywhere!! apparently they are pretty old tho.

i can never remember but LPG has fairly different requirements for AFR and spark... i should try and remember one day... or ask my mate

totally agree, dyno is the way..... start rich and conservative timing.. and get closer to the tooth

so... any chance you can find out what model your mate has? or a pic so i can wave at a wreckers

[30psi 4agte]

yeah i can ask him no prob.

From memory it is an MSD one though soething like this but from memory it is alot smaller amd doesnt have the launch control etc

http://www.ajusa.com/cgi-bin/stores/...0b6c753f7486e1

[chris davey]

Ey Chris, what's wrong with my setup? Doesn't that interest you enough? ;-)
:-(

Nothing. First lpg 1g I had seen in person

[love ke70]

oldcorollas http://www.gasresearch.com.au/gratus.pdf that is the a/r chart comparing petrol and lpg.
not all that different really
but its a slower burning fuel, so the spark can be sooner..

[stradlater]

Exactly correct love KE70 - Slower burning so more advance can/has to be run. Nothing special there.

Brian: It is not specifically illegal to open up a converter. It is possible to open up a converter, modify it so that it better handles boost. That's the type of converter I have in my car. Two infact. They are modified to better handle the boost, the diaphragm is changed.

The balance pipe runs from just after the turbo outlet before the intercooler. The pressure difference between the inlet and outlet side of the intercooler doesn't make a lick of difference to the convertere particularly if the system has been tuned for it, it's all relative and when it's setup properly it won't make a scrap of difference.

[love ke70]

ok, so your saying you have to get the convertor set up properly for it.
does that mean i should take the car to an performance lpg specialist and get them to also tune the ignition controller?
or is that best left to the place i sourced it from, and try and integrate the parties together?
if it helps its a mallory hyfire VI

[love ke70]

hmm anyway
i blew in the convertor and i could hear the diaphram move and stop so it all seems good.
only one problem left to work out, which ill start a new thread for, heres the link if anyones interested

woops, try this : http://www.toymods.net/forums/showthread.php?t=6813