The V8 Owners Forum -

Just curious - but do you do enough miles in a 40 odd year old car to make this conversion economical?

Hi all,

I've been a bit of a lurker on here but now have a request for some specific advice.

I've been in touch with Tinley tech about an LPG system for my p6. It's an early p6 with 10.5:1 engine and hs6 carbs, along with a mechanical fuel pump and an aftermarket distributor from simon bbc.

Been looking at a closed loop system with the tank in the boot (will leave the spare at home and replace with a foam canister). I realise I'll have to weld a boss onto the downpipe, but it seems like the right way to do it to me?

Am I doing all the right things? Anything else I should consider before I splash out on this?

Thanks in advance,

Rich

Hi - thanks for the reply! A good question and one I've thought about.

I use it everyday and currently spend nearly 200 a month on fuel.

The kit costs just over 600 all in plus £50ish to get it certified (so i'm informed?).

I was thinking i'd get that back in 6 or 7 months based on that... obviously correct me if i'm wrong

Cheers,

Rich

Thanks that's some helpful feedback! My maths sounds right at least

i've got a kit from tinley tech on my discovery, its probably quite similar
i lose a few mpg on gas vs petrol, but as you're running carbs i'd guess you might actually see an improvement.

getting it certified cost me a bit more than 50, i think it was more like £150?

other than that, just go for it. if you can roughly halve your fuel costs, to £100 a month, it'll pay itself off in no time

I bought my Bigas injection system from Tinleytech @ 8 years ago, always found them helpful

System has worked well I've covered @ 65k miles in my Range Rover Classic.

You might be making it overcomplicated by going closed loop.

I have an open-loop system on my V8 on SU's. Once tuned up, it is absolutely fine, and I don't even start it on petrol.

The high compression will work in your favour.

Chris.

I bought my Bigas injection system from Tinleytech @ 8 years ago, always found them helpful

System has worked well I've covered @ 65k miles in my Range Rover Classic.

Sounds like I'm doing the right thing.

Closed vs open loop:

I take this as being the difference between letting the butterfly in the carb control the gas flow compared to an 'engine management' type approach where the right amount of gas is pumped through in the first place. Is this a fair description?

Tinley were the ones who recommended closed loop for improved economy and performance.

Thoughts?

Many thanks for all the great advice,

Rich

So theoretically at least it is the most efficient option!

Thanks.

Rich

yes, the closed loop system will use a lambda sensor in the exhaust to monitor the air/fuel mix, and adjust the gas flow accordingly. the butterflies in the carbs will still be needed to control how much air and fuel get into the engine

Indeed theoretically closed loop is better. But carburettors work OK for most people, and we only went fuel injection for emissions reasons, not performance.

But if the kit is priced well, and Tinley Tech will support it, then go for it!

Chris.

ChrisJC wrote:Indeed theoretically closed loop is better. But carburettors work OK for most people, and we only went fuel injection for emissions reasons, not performance.

[Snip]
.

Well, one of the first UK EFI cars was the SD1 Vitesse, and that was definitely for performance. As was the earlier Triumph PI. And all the early adopters of injection did so for performance reasons - it was very much later carbs disappeared for emissions requirements.

Cheers guys. That's my mind made up.

I'll post back with an update when i fit it