My car runs CNG and Gas. So it is bi-fuel, and from what I understand if you look at the run files for the CNG program there is a unrecognizable, non-tuneable file. This car burns CNG 95 percent of the time, 5 percent fuel. The great thing about CNG is 130 octane, so a compression boost is very necessary, I will run premium fuel when burning gas. This car is used to haul 4-5 people with a trailer full of camping and backpacking gear, I drive it all over the country and reliability is a big deal. I need to know how far I can go on the stock tune, I will likely install a wideband just to keep an eye on things. Also, my ar is a specific year in my state that can be tailpipe smogged for emissions, so a cel is no matter, I have a manual in the car and had to keep the CNG ecm so I have a check engine occasionally anyways.

If the engine is an air pump and I open everything up I cant see why the stock tune wont just adjust fuel trims. Compression should not matter either. As for the cam it will be very mild, or maybe we can do 1.6 rollers if a cam will screw with the stock ecm. I really just want 15-20 hp/tq, which should be easily achievable with my build, here is my proposal:

Decided I am going to buy a low mileage engine and put it on the stand.
Have the new cam on hand (need to decide specs, handle stock springs so .460 lift MAX I think?)
First check all bearing clearances on the rods and mains
Then mock up the new cam and check for intake and exhaust valve to piston clearance and rough idea on rocker geometry
Then pull the head and check the block for how much can be decked
Using that info I can determine how much to mill off everything, max on the block, the rest on the head, I think .090 intake and .135 exhaust for clearance minimum on the valves to pistons
Then I will check the valves for how well they are seating, determine if a valve job is necessary and if so decide on +1 valves
Then port and polish the head
Then I will tear the engine down and take it and the head to be milled and cleaned
Then I will install the stock used bottom end in the block (assuming all clearances were ok, maybe fresh rings and a hone)
Install a new oil pump for sure and chain if necessary
Reassemble the top end with stock springs, lifters and rockers
Measure for exact pushrod length
Final assemble motor

2.3 throttle body
Header
No cat
30 inch resonator
Dbx Muffler
Build a very basic intake

No cam, bigger tb's are silly on mild na cars and since our tuning based on throttle position, a bigger tb will make you run lean at part throttle. P&p may be too much too.

We'll have ryan chime in since he must know ln2's well.


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I would love to test a CNG car, but I have not seen one for years! Before dumping all the money/time into the mods, I would first want to know how the PCM will react to the limited tables... Interested.....





P&P Tuning
420.5whp / 359.8wtq

i dont think a p&p is to much on the ln2 i just got mine done a couple weeks ago and i see a huge difference now with a bigger throttle body, intake and injectors i probly see a little more cause the stock injectors r maxed out but as for a cam the is no need causeonce u have gotten to the point the motor is really at its max as far as n/a goes

Excellent, some feedback from similiar mods.

So how do you know your injectors are maxed out? What size injectors did you end up with?

I am wondering if I can build the engine, and then just swap to bigger injectors until I get good a/f readings. I may forget about the cam and just look into 1.6 rockers, that way the gains are very slight and the ecm can run it. Researching that now.

After reading on the 1.6 rockers I dont think I am going to mess with a cam. A mild cam will give me the same lift as the rockers, well almost.

So now thinking:
Low mileage engine
Check the valves for how well they are seating, determine if a valve job is necessary and if so decide on +1 valves
Then port and polish the head
Deck the head .030
1.6 rockers (Proform with ARP studs)
Stock lifters, spring, pushrods
2.3l tb
Appropriate sized injectors
Header
Still no cat
Same muffler
Oil pressure and a/f ratio gauges
Find a better clutch
Just bought a fuel pump today

i have the stock 110cc injectors still im not for sure on the injectors being maxed out but if they arent there isnt much left they can spray out. i got 1mm oversized valves also thats another thing i did when i got the p&p the stock roller rockers r good enough unless u want to turbo in the future but u are then i would save them until u have the motor built and do it all at once just to save the wear as for the 2.3 tb i dont know much about im about to get the rsm intake and throttle body for mine and a clutch and flywheel will help alot just put new axles in when u get all of it done cause i snapped my driver side axle

Just to clarify, the stock rocker arms are NOT roller rockers. If your trying to squeeze out everything you can from the top end while still being on the stock tune, #1 you will definitely want the 1.6 roller rockers, and #2 you're insane. Not sure how the CNG setup is, but the normal factory tune sucks. Bigger injectors might help a bit, as will a bump in compression. Will be interesting to see how different the factory tunes actually are.

actually the stock rockers in a 2200 r roller rockers no they dont have the roller tips like u would get from crane cams or a company of that type but they r roller rockers so look again and i dont have the cng i never said anything about my fuel injecting tuning setup but it is tuned but tony palo. so before we start getting all katty...