I have the s**t impco elbow mixer that goes to the TB. Really noticible at higher RPM and now when I change gears / take off my tyres don't squeak before gaining traction

I see no point in putting a decent cam in if the intake isn't on par

I also don't want to buy a GRA TB - too exxy plus install/tuning = $$$

a cheaper way?

thanks

Shame cos its a manual EF in great nick with XR6 gear.. still would only sell for 3k so cant justify spending a grand on improved air intake

cheers

Even a GRA Carb gives some restriction, when compared to a car with no LPG installation.

You have to choose between the flexibility and economy of having LPG in the car, or spend the required amount to make the best of both worlds.

Ideally, if performance is what you want, you can get good performance from a dedicated LPG install, and tune the engine, shave head for higher compression, GRA TB etc. With dual fuel, there will ALWAYS be compromises.

For my install, I have been toying with some sort of LPG mixer bypass system, that will allow close to free flow air while on petrol.

BenJ

thanks for the imput ben

i don't care for a slight restriction, what i do care for is the massive restriction i have right now.

the impco elbow mixer sits between the standard TB and the airbox and the diameter inside is 1.5" or thereabouts meaning there is a great bottleneck.

all i really want for kw performance is to add a decent cam to the setup, but i am thinking whats the point if it can't flow enough air for the standard ticky engine as is..

say i do fit a cam.. likely a CMS stage 2... how effective would it be given the restriction?

I rang them up and they said chuck the cam in then go GRA in that order for ease of installation. When asked about performance without the GRA they said the cam would still 'go harder' but obviously not as much.

Anyone with experience of a cam on an LPG motor (without a good flowing intake?)

Anyone could make an assumption? say with the intake it is you would only be getting 70% or so of the cams maximum output on said engine?

I do know of a chap who got 143rwkw running dedicated LPG using that Impco 200 mixer. He is moving to a GRA unit, as he has reached the limits of flow.

In my car, if I compare running on LPG to running on Petrol, using the LPG intake piping and mixer, I notice quite a difference between the two fuel types. It is hard to describe, but on LPG the car pulls strongly to about 4000rpm and then sort of flattens but keeps increasing it's revs. On Petrol, it will continue to accellorate to the redline, and feels stronger than LPG from 2500rpm up.

If I then compare running on Petrol without the mixer and piping, to a factory Petrol intake, the car is noticeably stronger throughout the rev range, especially from 4000rpm up.

I too am considering a cam upgrade. The CMS2 or 2.5 are some of my options, as well as a Wade 1673. It is possible to richen your LPG mix to allow more fuel in, therefore allowing it to pull higher in the rev range, but at the sacrifice of economy. I lost around 20kms a tank by making my LPG mix slightly richer, but was less of a compromise in daily driving, compared to Petrol.

I however am not focussing on Max RWKW, but on increases in Mid Range Torque, as that is where I do 95% of my driving. The cams I am looking at are designed to come in at around the 2500rpm mark boosting the midrange nicely.

My car is a Manual, and I have observed that my driving style changes when using the LPG compared to Petrol. On LPG when driving with zeal, I will short shift at about 4200-4500 to keep the engine in it's power band, but on Petrol I let it go out another 1000rpm.

Anyway, hopefully, this gives you a bit more to consider.

Cheers
BenJ

thats quite interesting re 143rwkw on an impco 200

do you know if this was just a stock sort of lpg set up and the engine had some work done to it or a bit more complicated?

similar to you i don't really care for high rpm kw, prefer something that fires as soon as 2k and pulls through to 5 rather than just a massive 5k peak. no point on the street is there? just want 2nd and 3rd to pull through harder..

thanks for the info

i got 136 kw with dual fuel running a impco 200 and 139 on petrol. i have a gra ready to go on once I have some time to tune it all.
My original motor was built for gas running 11.2:1, ported head bigger valves etc and running a CMS stage 3 cam. Since the motor blew up due to a valve failure, I have changed to bigger valves again, stiffer springs, single collet stainless valves and more porting, similar comp. Once the GRA is set up will be dynoing it and hunting for more power. At the moment its really good from 2500 till redline, with a very nice note at idle.

shows the potential of the impco mixers then doesnt it..

so thats reports of 143 and 137rwkw from the 200 series....225 should net a bit more...plus I think there could be some gains porting it too....