Re: Best A/F ratio for power?
 

So when the A/F ratio goes rich at full throttle, the ECU is actually HURTING performance to keep the engine from being damaged? Isn’t engine damage from running lean really only a concern on high performance or forced induction engines, or can a stock little D17 be damaged from running lean too? Thanks.

Re: Best A/F ratio for power?
 

any engine can become damaged from running too lean

Re: Best A/F ratio for power?
 

You need NOS.....

Re: Best A/F ratio for power?
 

So you need NOS for the engine to become damaged when running lean?:rofl:

Re: Best A/F ratio for power?
 

erm... Are you joking?

recommend lots of reading - these questions are not really for these forums.

don't know, go see if there are engine theory forums around

although at the level you are at, i would say they will boot you out.

Re: Best A/F ratio for power?
 

I was obviously joking lol.:roflmao:

Compression increase?
 

I am trying to improve performance, and increasing compression is obviously one way to improve performance and reduce fuel consumption. I have a 2005 Civic with a fully rebuilt D17A1 bottom end and a D17A2 oil pan and head. As far as engine mods go, I have a D16Y8 intake manifold, custom 3 inch PVC cold air intake, DC Sport 4-1 header, 2.5 inch straight pipe exhaust and a Crower Stage 1 camshaft. I am thinking about increasing the compression ratio above the stock 9.5:1, and I have to choices that I know of: VTEC 9.9:1 pistons, or GX CNG 12.5:1 pistons. My thought on the first choice is that I highly doubt that going from 9.5:1 D17A1 pistons to 9.9:1 compression D17A2 pistons would have any effect on anything, and I think that a 4% compression increase would be a waste of money. But on the other hand, GX 12.5:1 pistons probably wouldn’t run on 93 octane fuel without knocking, and 93 octane is the best fuel that I have available. So here are my choices:
1. Be happy with 9.5:1 compression and leave it alone (Very boring)
2. Increase to 9.9:1 compression (Waste of money and still pretty boring)
3. Increase to 12.5:1 compression (Scary!)
What would you do?

Should I polish my intake manifold? Poll
 

I installed a D16Y8 intake manifold on my D17A2, planning to polish the inside of it with a small flexible ball hone because it is very bumpy. Then I heard that polishing the inside of it can cause problems with fuel atomization because the air will flow “too smoothly”. I also heard that the bumps actually speed up airflow like the bumps on a golf ball. What is the truth about polishing the inside of an intake manifold? Will it help or hurt performance and gas mileage? I would think that it would help because I presume that air would flow better through smooth tubes than bumpy tubes. I also presume that the air won’t heat up as much going through smooth tubes because the bumps add surface area for heat transfer to take place. Wouldn’t the bumps cause the air to “drag” more on the inside of the intake runners? Thanks, I’m looking for ways to improve the performance and efficiency of my engine, even slightly, for cheap.

Re: Should I polish my intake manifold? Poll
 

None of those techniques will produce enough of a difference to be deemed worthwhile on this engine.

A raw casted surface is very different from engineered dimpling so saying that it'll produce a similar boundary layer for laminar stream enhancement is likely not proven empirically or mathematically.

That said, smoothing the walls can, in some areas or instances, affect fuel atomization and wall wetting but if the injector is firing more directly into the intake port of the cylinder head (which you're NOT talking about polishing), it likely won't make a difference.

Re: Should I polish my intake manifold? Poll
 

Thank you. I guess I’ll try it and report back as long as it can’t hurt. Since the stock plastic one was smooth, I guess this one being smooth won’t be a problem. I’m not expecting to gain 10 HP or something crazy like that, just trying to improve performance a little. I’d be happy with a 1 HP gain since it’s free. A few changes that add a couple HP each add up to a noticible difference on a little D17 lol.

Re: Best A/F ratio for power?
 

For what type of fuel? Every fuel type has its own ideal ratio for max power.

Assuming gasoline is 12.5:1 (lunch break, no time to look it up), How can you adjust that for variations in the alcohol content in most of todays pump gas?

You aren't.

Learn about "stoichiometry of fuel combustion"

Re: Best A/F ratio for power?
 

So would injecting more fuel than you can burn make more power? I wouldn’t think so. I would think that the smallest amount of fuel that you can inject while still burning all the oxygen in the cylinder would make the most power, but obviously run hotter.

Re: Best A/F ratio for power?
 

Read up, son.

Re: Should I polish my intake manifold? Poll
 

Unrestricting about 1,5 cubic feet of air per minute can gain you 1HP maybe.

Being that the throttle body is more narrow than the intake, your efforts likely only make it slightly harder for your PCV to recoat the intake with nice layer of gunk.

Re: Best A/F ratio for power?
 

Watch some youtubes in which people are running their engine on fuel vapor.
In order to achieve higher mpg's they're injecting gas vapor through the throttle body. Is this the most effecient burn? Think it's running lean?
Does duct taping a plastic gas tank somewhere in the engine bay sound like a safe proposition?

Strut mount problem?
 

About 2 months ago, I installed new KYB GX2 front struts, Godspeed lowering springs and new Moog outer tie rod ends in my 2005 Civic. I plan to install lowering springs and new struts in the back soon. When I removed the old struts, however, several round metal balls that looked like ball bearings fell out of each strut mount. Unsure of what to do and not having extra strut mounts, I just reassembled it and pretended like nothing happened. The car drove GREAT for about a month, possibly the best it ever drove, despite the strut mounts. But about a month ago, the car started pulling to the left. It seems to pull worse at higher speeds. It feels like it has a bad alignment issue. I have to force the car to go straight, because if I don't, the car drifts to the left pretty badly. I am wondering if this could be caused by the strut mounts, or if the new struts and springs settled and it just needs an alignment. How do I know? Thanks, I am unsure of what to do next.

Re: Strut mount problem?
 

Does the pull change severity with braking or acceleration?

Also, it's the strut mount bearing that fell apart. Probably like $35-40 from the dealership. Just over $30 shipped if you can wait a bit longer. I had one fall apart when I first did a spring swap. Made sure every ball was clean and in place before I replaced them and had zero problems. Even endured a cross country road trip.

Here's the part number (for just the bearing) if you need it: 51726-S5A-701

Re: Strut mount problem?
 

Thank you very much. Would strut mounts make the car pull to one side? Also, are the strut mounts supposed to fall apart when removed, or did I do something wrong? Thanks.

Are cheap strut mounts OK?
 

I understand that you get what you pay with car parts. However, a strut mount seems pretty simple and easy to produce to me. My question is if I should get cheap strut mounts, or if quality strut mounts for 3X the price would effect the way the car drives. I really don’t want to pay $50 each for name brand strut mounts when I can get cheap ones for as low as $17. On the other hand, I really don’t want to buy crappy strut mounts that will cause the car to drive poorly or ones that will fail 2 months after I install them. I need strut mounts because I am an idiot, and somehow, half the ball bearings fell out of each front strut mount as I was installing my new struts and lowering springs. Surprisingly, the strut mounts don’t rattle, but now the car pulls to the left badly, I presume because of the strut mounts. So can I get away with cheap strut mounts, or do I need to pay $50 each for name brand strut mounts to get something that works correctly? Thanks, I’m not sure what to do.

Re: Compression increase?
 

Deck the block and or head?
Shaving a bit off will increase compression....just make sure the valve train clears.

Re: Compression increase?
 

Well, the head warped be 8 thousandths of an inch, so it was resurfaced. How much did that increase my compression?

Re: Compression increase?
 

all depends on how much they took off.
sounds like they too off a min amount.
I would use this compression calculator or something like it to start with.

http://zealautowerks.com/dseries.html

Re: Are cheap strut mounts OK?
 

At least use a good dab of quality bearing grease on the cheap parts..

They likely only come with the oily sweat of the underpaid workers as the only lubrication..

Litterally 30% of your cars weight gets pressed down on that bearing at all times..

Re: Are cheap strut mounts OK?
 

So for the car to drive properly, I need name brand strut mounts, like from KYB or Monroe?

Re: Are cheap strut mounts OK?
 

they wouldn't sell them if they didn't work....

they will work just might not last as long as more expensive/oem parts....
a dab of grease like slumpertcivic said will help with longevitiy

Re: Are cheap strut mounts OK?
 

So they will work well, but possibly not last quite as long?

Re: Are cheap strut mounts OK?
 

they wouldn't sell them if they didn't work....

they will work just might not last as long as more expensive/oem parts....
a dab of grease like slumpertcivic said will help with longevitiy

Re: Are cheap strut mounts OK?
 

They sell all kinds of cheapo crap that doesn't work

Inquire candidly about return rates lol

Does the downstream o2 sensor effect anything?
 

I have heard from a friend’s tuner that the ECU will freak out and run rich if the post cat o2 sensor is missing. Is that true? I thought that the entire purpose of the downstream o2 sensor was to make sure that the cat is working? I didn’t think that not having a downstream o2 sensor would effect the car at all besides causing an engine light. Who is right?

Re: Are cheap strut mounts OK?
 

Agree. If everything companies sold worked, there wouldn’t be scams like this: