Chipping a Factory Bifuel from 140 to 170bhp

[CNGBiFuel]

I'm hope Mr. Swede will along for this one.

It is a common mod for many to rechip the stock petrol flavour Volvo B5244 5 cyl engine form 140 to 170bhp. Volvo for marketing reasons actually hobbled the engine, so that you paid more in the showroom to get 170bhp, whereas the engines are truly are identical. It's a software rechip, nothing more. Which is why the showrooms like it. It has become common amongst amny manufacturers to do this, pure gravy for them. VW do it with their vans.

Now, I ask with a factory Necam Bifuel does this present a problem? As i get it, the gas end is told what to do by the chip anyway so the power increase should be universal? (I think).

For me I never run petrol, so if all I got was extra giddy-up on petrol the rechip would be of no use. It is on gas that I want my grunt. Mine being CNG I lose a fair bit of 'talks' (sic) low down over what I get on petrol. And my tank adds weight, compared to that 'aerosol can ' thing they put in LPG cars, this is a TANK! So I'm slower, and what with less grunt too...

I'm no boy-racer, and I'll not bother with er, Barrification....

http://www.barryboys.co.uk/phpBB2/vi...=17065&start=0

but a bit of grunt on CNG so that it at least brings it up to the grunt with std. petrol performance would be nice.

Would I be playing with fire here? Or would I jsut get more grunt on petrol?

Dai please guv' wot you reckon?

[reggit]

I asked the same question of one of thee tuning companies (shark I think) last year and was told the bifuels will tune to 175 with no issues and run happily on lpg in this state. Can't speak for cng I'm afraid. Just never got the spare money to do it!

[classicswede]

With a normal LPG/CNG conversion you will not have any problems other than needing to adjust the injector size or gas pressure.

With the factory fit things are not quite as simple but it should be possible and not cause any issues. You will probably find the CNG will take better to the higher cylinder pressures.

[CNGBiFuel]

Thanks, my thoughts too, and logically I see no issues. Dare I say, I have probably one the rarer V70s in the country a RHD P1 CNG, so i'm jumpy. if it fouls up, I'm shafted. There were only two made and the other I know went in the crusher, parts simply don't exist. A repalcement for my CNG Necam box anywhere, even in Europe will be hard to get, here in the UK... well forget it.


I take your point Dai. CNG needs higher compression ratios than LPG. The CNG car is more hobbled than a LPG car as a result of the Bifuel requirement, and I take it that a rechip changes valve timing so may bump up the compression a tad as a result.

I understnd these rechip merchants can wind it back to stock if all else fails.

[classicswede]

Boost and ignition timing are all that will be changed that I am aware of.