Re: What would happen if I increase compression to 12.5:1?
 

still confused,, if i ran 93 octane , 12.5 natural gas piston, couldn i use bigger injectors and still be safe?

i see on craigslist a low millage natural gas d17a6.. is listed cheap for parts..
what are the diffrencess? it has diffrent intake manifold .. couldnt i converted to gasoline .. ?
does it have vtec?

it has automatic tranny. are transmissions the same? i lost reverse on mine


i was hoping cheap all motor power might be better insted of fixing few issues I have on mine // thats if possible


couldnt i create a good combo , use my intake, reruns wires, not sure if it has vtec, vfac2 if it does, and then see what happens...

or maybe i fix the issue on mine and run cheap nitrus per dollar to kinda supprize people..
i still like all motor better, then nitrus runs out eventually and it costs to refill

Re: What would happen if I increase compression to 12.5:1?
 

A D17A6 is a VTEC-E gasoline engine. The D17A7 is the CNG engine. Just so you know.

Re: What would happen if I increase compression to 12.5:1?
 

sorry CNG i meant d17

Re: Are disc brakes really more effective than drum brakes?
 

No because the car was designed for rear drum brakes and everything else being equal changing to disc won’t make a difference.


Disc brakes hold up much better than drum when it comes to heavy, constant use so if you were racing the car then yes switching to disc and replacing the proportional valve will give you better results overall.

Does my exhaust sound good?
 

I took a video of the way my exhaust sounds. What do you think? I got yelled at by a neighbor for making this video, so it's loud lol.

https://www.youtube.com/watch?v=VIK6...ature=youtu.be

Re: Does my exhaust sound good?
 

Sounds like a fat lady talking a dump.

Re: What would happen if I increase compression to 12.5:1?
 

Honda doesn’t just slap together parts, everything is well engineered to work for its role.
CNG and Gasoline have different burn speeds as well as different burn temperatures. so the camshaft is different.
Pistons made from a slightly different alloy maybe. Torque band different so different gearing in transmissions would be expected.

Common issue people running Japanese transmission is pcm code because they have a different gear ration so the computer thinks something is wrong since it’s not getting the expected results.

I am sure all that stuff can be sorted out with enough trial and errors.

Re: How do I adjust drum brakes?
 

Not intending to hijack OP's thread but this is the part that I may not have done correctly. I do remember trying to spin the hub first without the tire and since it didn't seem to spin easily I would put the tire back on to rotate. I'll pull the drum off again and see if it comes off without too much resistance.

Re: Does my exhaust sound good?
 

I listened to your video with a good set of over-ear headphones:

A) Sounds like you did an exhaust or resonator delete..a.k.a. loud and shitty.
B) Sounds like your neighbor wants to throw-down with you for probably waking up her/his baby
C) Sounds like your breathing is labored walking up a few steps

Re: Does my exhaust sound good?
 

A) I have no exhaust on it for the moment.
B)That guy that was yelling at me doesn't have a baby, and he was sitting outside, so he wasn't sleeping
C) I have asthma, and the cold weather triggered it.

Re: What would happen if I increase compression to 12.5:1?
 

I understand that Honda engineers things for the application. I was just curious what would happen. Also, since you seem to know about the JDM transmissions having different gear ratios, what is the gear ratio differences between a BMXA and SLXA transmission? Thanks.

Re: Does my exhaust sound good?
 

For all of your neighbor sake..don't run that without an exhaust.
My son (while living with me/condo) did a muffler delete on his '07 Mazda 3 and got an earful from me and a few neighbors for a month. I made him get a muffler installed. Idiotic waste of money that was for him.

Harley motorcycles are f'ing annoyingly loud but there's a reason for that..so they can be heard when not always seen. Other than that loud exhaust on purpose are for d!ckheads.

Re: Does my exhaust sound good?
 

#1 If you live out side of city limits ask him why he hates freedom, is he a commie? If you live inside of city limits, you're probably violating some sort of db threshold and disturbing the peace or some actual legit offense.
#2 Sounds horrible.
#3 loud as **** and will quickly get old if you have to drive any real distance often..I'd try finding a large factory muffler for a vehicle with a much larger engine and mounting it, probably sound better and much quieter without being a restriction.

Re: Does my exhaust sound good?
 

I bought a Flowmaster DBX muffler. I am going to have it welded on soon.

Re: Does my exhaust sound good?
 

Sounds like utter shit, to be brutally honest. Don't run open header on a D17 (yes, I see that you have a muffler coming). You'll hate life. Something people don't realize: too little backpressure is a bad thing.

What size piping are you gonna run on your exhaust? Or are you just having a shop cut out the old muffler and weld in the new one on stock piping?

Re: What would happen if I increase compression to 12.5:1?
 

They're right you know, without some sort of means to correctly adjust the timing and fuel maps independently you're most likely going to continuously run into knock, which even if there's a knock sensor telling the ECU/PCM to retard timing to save the engine, it's still knocking for a moment, and may continue if it can't retard ignition timing enough, in my experience sometimes once an engine starts knocking under throttle it doesn't want to stop until you let off the throttle. If E85 is local to you then I'm sure you can run that compression in that engine, but you will need the ability to tune larger fuel injectors and adjust the maps, otherwise it's going to have a very short life. Also I don't know anything about CNG pistons and the differences between them and the stock unit, but i'd look them over carefully and weight them to see if they don't look to be designed to withstand the same load, as I don't think CNG combustion pressures are as high. Some proper pistons like Mahle units would be what I would go for, they use a different alloy than most every after market forged piston maker, it's a little less ductile / more brittle but weighs a lot less and is still a lot stronger than factory pistons, they make great street/strip use as you can set your piston to wall clearance tighter than with normal forged units which expand a lot more at operating temp. There could be other design differences between the CNG pistons and stock that could promote hot spots and knock, Are they dished, domed or ?

Re: Does my exhaust sound good?
 

OMG stop perpetuating that ignorant myth. You misunderstand the relationship with back pressure and exhaust velocity and their effect on scavenging. But back pressure is 100% completely undesirable.

Re: Are disc brakes really more effective than drum brakes?
 

Depends on the disk brakes and the drums in question. Disk brakes are very easy to change to a larger rotor, larger rotor if the proper brackets already exist to locate the caliper, they give a larger mechanical advantage and more breaking power. What Slumper said is potentially true if you're comparing a small set of disk brakes to a set of drums with similar stopping power. But in doing the conversion you can easily swap to larger rotors and gain a LOT more stopping power. Be aware there is no free lunch, and doing so may require larger wheels to accommodate the larger disk brakes. So even if static weight of the two different brake systems was comparable the need for a larger and very likely heavier wheel & tire combination is there which will effect performance in other areas, some good, some bad.

If tire traction isn't a limiting factor, and you do a conversion correctly and go to a larger rotor, yes you will decrease your stopping distance, how much depends on rotor size, calipers, pads etc. The more aggressive you go the shorter your stopping distance so long as you are using pads appropriate, you can go to aggressive in that "race" pads need to be hot to work. Cold they will be worse than stock.

Re: How do I adjust drum brakes?
 

If you've been driving it without a problem, it's probably not a problem

Re: Does my exhaust sound good?
 

Backpressure is always a bad thing. Scavenging is a good thing. And to answer your question of what size pipe I am running, I am running a 2.25 inch exhaust with a resonator and no cat.

Re: Does my exhaust sound good?
 

Agree. Negative pressure is a good thing though, which is why an exhaust can be too big, as stated in the video above.

Re: Are disc brakes really more effective than drum brakes?
 

Very good explanation, thank you. So would my car stop any better if I convert the rear brakes to drums? Thanks. +1 rep.

Re: Are disc brakes really more effective than drum brakes?
 

Drum brakes work very well and did so for decades.
Disc are a very simple design, but some drum brake setups are pretty simple too.
Each type has some pros and cons, of course.

Which type is better able to dissipate heat from repeated brake applications? Disc in most cases.
Heat, of course, is the enemy.
If you can jam the brakes and lock up all 4 wheels at speed, no matter which brake design employed..........no difference. (Also no directional control LOL)

Skidding tires don't make for short stopping distance though, no matter which brake design is used.
Stopping power is always limited by tire traction.

Re: Are disc brakes really more effective than drum brakes?
 

drum - enclosed. Keep heat in. Fade. If water gets in, it won't go out - Bad. although most modern drums are less likely to get water in.

Disc - open. better cooling. Less fade. First step after under water and water is removed.

Our cars are front heavy, most braking is done by fronts (still stock drum shoes at the back after 130k miles.
Proportioning valve is designed for that also, so as to not lock rears. Very few advantages on putting discs at rear, except for what i mentioned at start.

better tires are likely to improve braking, if tires are skidding (meaning there will be braking power left, not used by tires)

Re: Does my exhaust sound good?
 

Can't tell is trolling or....

But you're not 100% wrong, nor am I. Misuse of wordage is really what I'm doing. I'll just leave it at that. I'd rather not get into the nuances of it.

edit: I'm also speaking from firsthand experience with working with exhausts and utilizing knowledge gained from working in the engineering field.

Re: What would happen if I increase compression to 12.5:1?
 

This post kinda got me curious so......
CNG cars just don't exist in my corner of the planet so I dug into the parts catalogs a little bit.....comparing 2003 GX CNG D17A6 with the other versions D17A1 and A2

GX Pistons and rods have unique part numbers, I'd expect the pistons would be domed to raise compression, and rods might be a smidge different in length but I have no specs to go by on that...


Crank and wrist pins are the same for all 3 engines
Rings are the same too

GX Cam is the same part # as non-vtec D17A1,
that means the GX head can't be vtec


Stock piston to cylinder wall clearance spec is already dang tight.... 0.0004"-0.0016"

Re: Are disc brakes really more effective than drum brakes?
 

Again, it depends. Are you increasing the size of the front rotors as well? If so and tires are sticky, yes. But what people are trying to say is simply switching from drum to disk in the rear, won't do much to decrease a 1 hard stop, stopping distance with good tires on a clean dry road. What it will do, is help some in the wet, and will help some with hard repeated stops, but only marginal decrease in stopping distance. 85% of ANY cars braking is done with the front brakes regardless of drivetrain layout or weight distribution. It changes some depending, but the vast majority is always by far done with the front as weight shifts forward under hard braking.

Re: Are disc brakes really more effective than drum brakes?
 

OP: Is your question concerning drum to disc conversion related in any way to your unfamiliarity in drum brakes replacement (referencing another post of yours)?
I ask because I faced that situation earlier this year and up until that point I never replaced drum brakes. To me it seemed complicated compared to disc brakes. However, thanks to responses here, service manual and youtube vids it really isn't difficult. Actually, it went much quicker than I expected other than setting the proper adjustment...seem to take as much time as replacing internal parts.

I think a lot of people look at drum brakes as old technology and it is but, it's still being used on some new base model cars today: https://thebrakereport.com/drum-brak...ng-used-today/ LOL.. that link argues against drum brakes.
I should have known..it seems to come down to cost savings (brake/E-brake in one) for the manufacturer but acceptable on non-high performance cars like most stock civics are: https://www.web2carz.com/autos/every...rakes-obsolete

Re: What would happen if I increase compression to 12.5:1?
 

Very interesting, thanks for sharing. I have heard that the GX rods are stronger so they can handle higher compression, but I'm not certain about that.

Re: What would happen if I increase compression to 12.5:1?
 

Are the part numbers for the head and intake manifold the same as a D17A1 too? Thanks.