4000cc, 6 cyl, CNG/ Petrol Issue. Some imp questions

[noman8ff]

I just finished making a true copy of a modified air control system from a hard paper. Now having food. In an hour or so will post pictures of the design and would like to have your comments so that i finally do it with the air intake.

[alee1]

waiting

[noman8ff]

So it's like a butterfly which will be manually operated from the dash board through a "choke" like cable.

This is from the front. 60% air is blocked (you can change the size of the inner plate according to the vehicle)

Slightly from the top.

Now this picture taken from the top will explain it's working.

Point "C" will be the part which if the cable is pulled will move in a clockwise direction, resulting in opening of the inner plate.

A spring will be connected with point "A" from one side and from the small mark "x" on the other side. This spring will help the inner plate to move back when the cable is released.

On top of point "B" is the location of spring.

The two small arrows show the direction of the movement of this portion when the cable is pulled.

The bigger arrow shows the direction in which the air moves.

This picture is from the other side of the system.

Point E is the place where i'll drill a hole and will fix a bolt which will stop the inner plate from further movement.

When inner plate is fully opened.

Inner plate fully opened, pic from the top.

Inner plate fully opened. The spring fully stretched. Point "D" will have a stopper where the inner plate will stop.

[Proverbial_Slang]

I've got an intake (which means more than normal air) installed in my car (Khyber carby) which is running on CNG / Petrol, the car performes exceptionally well on both kind of fuels. Air intake is installed on a ventury.There is no issue when the car is idle either on CNG or on Petrol. The only care i have to take is to keep the air filter clean i.e. have it aired every now and then.

@ Proverbial_Slang, brother thanks for the reply. I would again ask the same question.

Would the blocking air is only bad for petrol or it harms the working on CNG as well. If it is only bad for petrol, than i'll think something different for blocking and freeing the air flow manually (from inside the vehicle) for both the fuels. And believe me, i have good ideas for that modification. But let me first get everyone's opinion.

My answer would be that blocking the intake is not good for CNG,nor for petrol. I personally experienced better mileage and improved performance on CNG with unblocked intake.

My CNG kit installed sweared that the car would not run properly and would give me horriblemileage if I removed the blockage, but it proved wrong.

I took my 1985 G11 Charade upto Maalam Jabba on CNG apart from several trips to Murree and Nathia Galley after I tuned it myself.

[noman8ff]

And all this air movement portion in my cruiser is of hard iron so will fix this mechanism in it. Any suggestions will be critically and positively taken. Waiting for your valuable comments.

[Xulfiqar]

find yourself a proper precision machined venturi - (they cost a lot but its worth it) the taper inside the venturi and the gas feed holes/slits are measured and aimed properly to suck gas from the regulator. I have done that on a carburettor Honda Accord (similar to a 2 brl pierburg in looks) and the engine can pull the car strongly all the way to the redline) - this requires that the regulator is of proper flow (not some stupid 1000cc car one) I have faced a problem of the regulator maxing out at 70% throttle load. I had to find a heavy duty regulator for my moms 1.6 litre carby accord with the precision venturi. (this regulator has 2 vacuum lines from the manifold too) - and I have the heater pipes connected to it also

please note that all this time there was never air blockage - and I always use Donaldson paper air filters - they last about a year in Karachi dust - everyday travelling of 60kms at least. -

Go ask the CNG installers for a precision venturi for your engine - (its also called original italian venturi) - secondly check your distributor centrifugal advance mechanism for smooth operation - it should not be floppy or notchy - and most importantly the distributor cap and rotor should be original or similar parts (i have seen a dumb configuration of using a smaller rotor in a larger cap) - the vacuum advance should also function properly - in your case - on slight throttle

[onlyfaith]

congrats on your buy.
an old jeep doing 130 km/hr is awsome!
your jeep is in mint shape masha Allah!

[alee1]

lo0ks go0d.really go0d,tells story how much work is done on it just at first glance, but make sure that it is properly jointed at ends and air dosent blows it into engine with its flow.4k cc engine w0uld need l0t of air and at higher speeds air flow/vel0city wud be higher.
secondly make sure u have s0mething t0 stop it from changing its positi0n when high velocity air is passing through it,cuz air flow may push the choke more or less disturbing your tuning settings.some mechanism with lockable gears would be a my advise if you could do it.
regards

[noman8ff]

alee1, brother thanks for the suggestions. Will work on it on saturday.

[uiv]

So it's like a butterfly which will be manually operated from the dash board through a "choke" like cable.

I made pretty similar thing for gas/air intake. But that was motor controlled, and I'd say that your manual-cable version is better. I'm planning to make one, on your recipe, for the exhaust.

This thing worked fine for me, till one day when a bolt from the butterfly got sucked in by the engine somehow, and ended up in disaster

Please be very precise and careful with everything :-# Best of luck.

[imtishal]

@noman

Do what xulfiqar has said and probably u wont be needing any blockage in intake.BUT on the other hand venturi itself sits on TB and hence blocks some air.
I would suggest to have a look at the baleno's FF cng set up.It uses an electronic air blocker just before the air filter housing,and takes signal from cng kit,as soon as u convert the vehicle to gas the air blocker closes and when converted to petrol it open's up completely.But since ur jeep is carby so i guess u'll need to manually send signal for blocking/unblocking But i think it would be better looking and less hassle then cable operated set up.

As for the air blocking being bad or gud.A frd bought a cng fitted VTI 2006 model,removed the cng cylinder as he wanted to run her on petrol.He was coming back from lhr to isb on M2 @ speed 170-180kmh when suddenly one of the connecting rods broke.we were amazed that how can a connecting rod could break for such a 'high end' car.Later on we found that the venturi inside air filter housing was not removed,which restricted air flow into combustion chamber at such high speed resulting in incomplete power stroke of piston and caused the connecting rod to break.

[spectra]

@ ahmadbila, janab aap nay meray dil ki baat keh di. My mechanic is also very sound and deals with all new and old technology vehicles. But he tells the same story what you say.

@ xenerking, thanks, will discuss this option as well.

I dont think getting to work without air blockage is a bog problem because Carbuerator barrel itself is an air restriction, Have to see however how much suction its doing considering displacement of engine which is unknown territory for many petrol and cng mechanics

[spectra]

If you want to do the butterfly thing then NIssan Diesel CD20 engine setup has a butterlfy attached to its air cleaner housing, that will be an ideal fit in the intake path without much desi fankaari. Intake should be dust free so cant risk much.

[noman8ff]

@ uiv, Agreed. I think you must have installed your system between the air filter and the carburetor and thats why the bold reached the engine. I am planning to do it even before the air intake so no issues.

@ imtishal, As far as the venturi is concerned, if i am not wrong, on CNG it controls the air flow well but on petrol, some 15 to 20% air still remains blocked. And thats why your friend's car got the damage. So for an old vehicle like mine, some very little blockage is bad.

@ spectra, good idea. If its true, that will be amazing. Thanks.

[alee1]

alee1, brother thanks for the suggestions. Will work on it on saturday.

most wellc0me

[hshakeem]

6 rupees a km in army and isi jeeps, this is where all our tax money goes into

anyways

air blockage has no harm on cng . its all done to have a perfect combo of air/cng and to make the car iddle smooth
however on petrol, engine has to put more stress for air suction, economy and performance drops from the blockage

venturi also restricts air to some extent but if right now ur air intake is blocked 60 percent, even after venturi, still u would need to block the intake

i think the manual choke idea isnt bad if u frequent run the car on petrol. most cng users run car 99 perc on cng. so even if its 80 percent blocked, people dont care

If you give the required quantity of gas you do not need to block the air. Increase the gas flowing into the engine and unblock the air. the reason could be that the injector opening is too small or the gas adjuster is closed or even the CNG regulator is small for the engine.
Air blocking is very bad for the the engine especially for the the valves / head.
I recently converted my 2004 Honda Accord 2.4L to CNG without any air blockage using BRC sequential kit. Initially a smaller gas injector was installed resulting in Kit's ECU converting the engine from gas to petrol at 5700 RPM. But later with bigger injector this problem was resolved. With lite foot on throttle I am getting Rs 3 to 4 per Km at an average speed of 100 to 120 kph.
Before that I drove Daewoo Racer (with 5 speed gear box) and 1984 Honda Accord 1.6L with Badini CNG kit and 60L cylinder. On highway I use to regularly get over 200km per refill.
Cheers.

[hash4u]

dont u think they would have tried opening the gas at max and tried reducing it gradually to see if it can be set without blockages ?

i have a corolla with 220,000kms, own engine, intake partially blocked without any problems

sequential = SIS kit ? after spending money of 2 kits on one kit,good mileage makes sense. glad ur happy

[vvaheed]

I just finished making a true copy of a modified air control system from a hard paper. Now having food. In an hour or so will post pictures of the design and would like to have your comments so that i finally do it with the air intake.

I like ur air control system. thats really nice buddy.

[vvaheed]

i've got an intake (which means more than normal air) installed in my car (khyber carby) which is running on cng / petrol, the car performes exceptionally well on both kind of fuels. Air intake is installed on a ventury.there is no issue when the car is idle either on cng or on petrol. The only care i have to take is to keep the air filter clean i.e. Have it aired every now and then.

wow

[vvaheed]

WoooooW