vt commodore gas performance mods?

[wade.b]

I have a v6 commodore on dual fuel just wondering if and of the mods you do for a petrol car will have any effect on the LPG like roller rockers

[bpefi]

What sort of LPG system do you have -if you dont know post some pics

[bpefi]

First thing to do is get it running properly on LPG & I would start with a Blos mixer off Ebay - this will give the gas the correct draw right across the rev range - which will make it easier to start & it will rev right out as it removes the restriction of the gas ring - if you have that type of system. This will put power on petrol back to normal. If it is a ring mixer the commodore ones are very restrictive. The next thing is to get a dual map Memcal for the computer (if you have the right computer that is) once you have this fitted you wont need a petrol start as the computer will control everything including switching the fuel pump off. Once you do these two things it will run much better & you can go with some more of the common mods such as extractors etc.

Two other things that have given me noticeable power increases & a huge fuel economy boost was to fit Pulstar plugs - they work brilliantly & they will stop a lot of backfires - I have had two coils fail on gas & normally it would miss / back fire bad for ages - with the Pulstars they just keep working until they just stop. They can use every bit of energy to fire the plug properly.

The other & you may not notice this as much & that would be changing oil to the thinnest that you can without using excessive amounts of oil. I am using a 0W40 Mobil 1 synthetic - this will give you all the cold start protection & as well it wont use as much power to drive the oil pump. You may not notice the difference - but on my 2.0l Hilux I noticed a huge difference. Being on gas I don't change my oil until its done at least 30,000 k as I usually top it up every 5000k & with a synthetic / lpg you can get away with this easy.

A diff change will make a lot of difference - I am running a vs v6 in a Hilux with 3.7 ratio diff & I am getting 15k per litre around town & 13 on the highway on LPG & on LPG its powerful enough to stay with a std vs (on petrol) from the lights even with 1/2 ton in the back & an extra passenger in mine.

I have since done the motor up - fitted 10 thou oversize & high comp race pistons / double row timing chain & had the valve seats done to stop valve recession - looking forward to giving it some once it settles in.

With my cold air intake I made a custom job - drilled a 3 inch hole through the bottom of the air cleaner box & fitted some pvc piping & hooked into one of the air scoop in the bumper - so I get an air ram effect - this helps a lot to overcome the restriction of the air delivery - the bends & convoluted tubing that slow things down. Just watch out for water on the road though as this severely restricts you from driving through flood waters...

You can make your own spacer for the manifold - I haven't tried it - but I don't see any difference between making it out of ply or something like that to buying the real thing - the spacer lengthens the inlet port as std they are pretty short - longer you make them the more torque the engine will develop.

If you have done all of this - then your ready for things like extractors & roller rockers - but for the cost I cant see the rockers being worthwhile.
Good luck with it all

[wade.b]

hi the blos mixer sounds great. but i just cant seem to find one online are the impco ones similar or not as good?

[bpefi]

hi the blos mixer sounds great. but i just cant seem to find one online are the impco ones similar or not as good?

The supplier had some issues recently - I emailed him about that - if you search for mixers - pretty much everything on there is from the same person - so send him a message & ask when they will be available again. Impco are the next best thing but do have some restriction - but to fit this the converter has to be changed as its a negative pressure system