Mild build with fuel economy

[Hasbro]

This is directed at people like Talonxracer, LM and others that have the knowledge to back up their statements with facts.
This is a different direction compared to most mods on this forum. I'm really into hypermiling but love to stomp on it, especially around corners. I can see 50 mpg not too far in the future (my last tank was 455 miles without getting on the highway).
What would be an ideal build that would enhance fuel efficiency but still have a lot of fun in it? Top end hp numbers mean nothing to me if that helps. Stay with same block? Custom cam? Base RSX intake? No forced, trying to keep the weight down.
Thanks
Oh, car will weigh 2500 fully loaded so that is about 17% "more" hp right there.


This doesn't have anything to do with the first question but might as well ask; it's pretty much accepted that the A3 isn't popular for building big hp. but then there are some (Jaeguyoon) who have built the A3 with 190+ hp/144+ torque with a stock bottom. That's pretty presentable. What's wrong with that- price, durability? Just curious and couldn't find a Search answer.

[0h5ive_EP3]

what the hell do you have done to your car to get 455miles for a tank

i'll get 350 if im LUCKY!!! including highway

[Hasbro]

what the hell do you have done to your car to get 455miles for a tank

i'll get 350 if im LUCKY!!! including highway

That's only 36.4 mpg (12.5 gallons). And I still haul butt around corners. There's actually quite a bit to it and most of it is in direct opposition to a "performance" car. For instance, combine a lrr (low rolling resistance) tire with a performance suspension not tuned to the tire and you will wind up in the weeds (or in a ravine where I live).
Here are some basics: http://ecomodder.com/forum/EM-hyperm...ecodriving.php

[talonXracer]

You are at about the max mileage level for the Kseries and still have any performance. You will need to loose weight on the chassis now to get any better MPG.

You can opt for a 4.0fd and a TSX 6th to reduce rpm's on the highway. I get 34-36mpg on the highway with a 4.3fd. The Federal Govt just recently reduced the fuel quality levels again, so dont expect any miracles..................

Ceramic coating of the pistons will allow for a slightly leaner A/F before detonation. That is the real obstacle to high fuel mileage.


Our tank holds 13+ gallons

[Deadphishy]

If I were going to build a motor for MPGs this is what i would do.

I would take the a3 and put in Titanium rods, and super lite 10/1 compression pistons (high enough for good power but still running 87-89) coated of course. Cleaned up crank, and lighter flywheel. a3 cams are pretty good, but you'll have to try to stay out of Vtec. I would use the a3 head because its smaller ports allow for a higher low RPM intake air Velocity. Stock Exhaust with a CAI.

If you don't mind running premium gas, maybe 12/1 cp pistons.

Full core racing radiator (Cooling the motor you will be running lean)
k20a2 oil cooler
5 ep trans with tsx 6th
Very light Wheels with 195-185 wide tires.
Good Oil, Good Gas, and a lite foot.


Thats my 2 cents.

[EPSU3]

This is directed at people like Talonxracer, LM and others that have the knowledge to back up their statements with facts.
This is a different direction compared to most mods on this forum. I'm really into hypermiling but love to stomp on it, especially around corners. I can see 50 mpg not too far in the future (my last tank was 455 miles without getting on the highway).
What would be an ideal build that would enhance fuel efficiency but still have a lot of fun in it? Top end hp numbers mean nothing to me if that helps. Stay with same block? Custom cam? Base RSX intake? No forced, trying to keep the weight down.
Thanks
Oh, car will weigh 2500 fully loaded so that is about 17% "more" hp right there.


This doesn't have anything to do with the first question but might as well ask; it's pretty much accepted that the A3 isn't popular for building big hp. but then there are some (Jaeguyoon) who have built the A3 with 190+ hp/144+ torque with a stock bottom. That's pretty presentable. What's wrong with that- price, durability? Just curious and couldn't find a Search answer.

nice, i'm in the same boat as you man. I don't want to add any mods that will reduce my mpgs. Averaging around 38 mpg with my bolt on A3 on stock tires and 87 octane

[Lucid Moments]

First off I would do what Doug was talking about with the final drive and the TSX 6th, but I would combine that with a 2.4L bottom end. Keep the stock bore and maybe run 10:1 or so pistons with some mild street cams. Something like the Skunk2 stage 2 or BC stage 2. Look into getting a really good header because there is a good bit of inefficiency in the stock header. I'm talking a custom header from Hytech or SSR or some similar place. You will want your peak torque to come in fairly low.

I wonder if the extra power you can get by running higher compression pistons is worth the extra cost of running premium gas? Thinking out loud here, but you can run 12.5:1 pistons on 93 octane fuel without too much of an issue. Particularly if you have the pistons and combustion chamber coated. I don't really know but I would look into it.

[Hasbro]

If I were going to build a motor for MPGs this is what i would do.

I would take the a3 and put in Titanium rods, and super lite 10/1 compression pistons (high enough for good power but still running 87-89) coated of course. Cleaned up crank, and lighter flywheel. a3 cams are pretty good, but you'll have to try to stay out of Vtec. I would use the a3 head because its smaller ports allow for a higher low RPM intake air Velocity. Stock Exhaust with a CAI.

If you don't mind running premium gas, maybe 12/1 cp pistons.

Full core racing radiator (Cooling the motor you will be running lean)
k20a2 oil cooler
5 ep trans with tsx 6th
Very light Wheels with 195-185 wide tires.
Good Oil, Good Gas, and a lite foot.


Thats my 2 cents.

You prefer the Si manifold. The RSX has more usable low end torque- wouldn't that be an advantage? Why a CAI? More flow and cooler air gives more hp but hampers fe. What about moving the Vtec up to say 2800 rpm (K-Pro)?

For this next tank I'm doing several changes so my average should go up a good bit. Probably the biggest problem for me is making short runs on a cold motor. I usually don't go very far so 40 mpg should be pretty easy under longer runs. After everaging 40 I will start working on the aero, which will be alot of fun and should get some good results as there are a lot of weaknesses.

Talonxracer, my weight reduction (300 so far) is helpful around town for sure although it wouldn't be as important on the highway. I do intend to change gears but that is on another thread (which you helped me on).

[Deadphishy]

the base DC5 manifold might help out. you'll have to have a base rsx ECU K-PROed in order to use it. (i think)

I got a bump in FE when i put on my CAI. Cooler IAT should allow you to run slightly leaner. How much? i dunno

[Hasbro]

First off I would do what Doug was talking about with the final drive and the TSX 6th, but I would combine that with a 2.4L bottom end. Keep the stock bore and maybe run 10:1 or so pistons with some mild street cams. Something like the Skunk2 stage 2 or BC stage 2. Look into getting a really good header because there is a good bit of inefficiency in the stock header. I'm talking a custom header from Hytech or SSR or some similar place. You will want your peak torque to come in fairly low.

I wonder if the extra power you can get by running higher compression pistons is worth the extra cost of running premium gas? Thinking out loud here, but you can run 12.5:1 pistons on 93 octane fuel without too much of an issue. Particularly if you have the pistons and combustion chamber coated. I don't really know but I would look into it.

Lol, I was holding off from asking about a K24 until the the A3 was discussed more but the torque of the K24 is really alluring without even thinking about the performance angle. Not sure about cleaning up the header, usually that reduces fe while enhancing hp. Or is the K24 header that bad? When I had my 04 CR-V I measured 37.5 mpg on an 800 mile trip. Imagine the mpg with the EP3 and some gearing! I imagine that the reason most people complain about the EP3's mpg is that once you go into vtec you are opening up the "4 barrel".

Does anyone else have any opinions re. Deadfishy's CAI suggestion? That's a surprise that I didn't expect.

Appreciate everyone's input.

[Lucid Moments]

Lol, I was holding off from asking about a K24 until the the A3 was discussed more but the torque of the K24 is really alluring without even thinking about the performance angle. Not sure about cleaning up the header, usually that reduces fe while enhancing hp. Or is the K24 header that bad? When I had my 04 CR-V I measured 37.5 mpg on an 800 mile trip. Imagine the mpg with the EP3 and some gearing! I imagine that the reason most people complain about the EP3's mpg is that once you go into vtec you are opening up the "4 barrel".

Please note I specified a custom header that would be tailored to your needs. Normally a performance header is designed to increase peak HP. Lets face it that is what most of the performance industry wants so that is what manufacturers provide. A different design should be able to make maximum gains where you want it which is in the low range. You will sacrifice top end that way, but I still think they can improve on the stock header for both performance and fuel economy

Does anyone else have any opinions re. Deadfishy's CAI suggestion? That's a surprise that I didn't expect.

Appreciate everyone's input.

Well duh? You definitely want to run with all the normal bolt ons. Those reduce pumping losses so they should improve fuel economy. I don't know how much the cooler intake temps really help other than from a stop. At speed I think there is enough airflow into the engine bay that a short ram would be fine. There is going to be some difference I just don't think it would be terribly significant. I could be wrong on that but I don't think so.

[Hasbro]

Please note I specified a custom header that would be tailored to your needs. Normally a performance header is designed to increase peak HP. Lets face it that is what most of the performance industry wants so that is what manufacturers provide. A different design should be able to make maximum gains where you want it which is in the low range. You will sacrifice top end that way, but I still think they can improve on the stock header for both performance and fuel economy



Well duh? You definitely want to run with all the normal bolt ons. Those reduce pumping losses so they should improve fuel economy. I don't know how much the cooler intake temps really help other than from a stop. At speed I think there is enough airflow into the engine bay that a short ram would be fine. There is going to be some difference I just don't think it would be terribly significant. I could be wrong on that but I don't think so.

Ok, missed the custom part. I disagree re. the normal bolt ons. Time and again they have been proven to decrease fe.

[talonXracer]

I would also retain the RBBmani and use that on a K24A2 rather than attempt to use the base RSX dual plane mani.

Even while moving, the CAI makes measurably more WHP and torque. The sRI is basically pulling heated air in, the wheel wells are not inlets, they are outlets for the radiator air flow, so placing a intake to suck in heated air isnt conducive to economy, the heated air will only raise cylinder temps.

No matter what header you have made, you must send it out to Swain Tech and have it properly ceramic coated, it reduces underhood temps TREMENDOUSLY!!!!

Make sure to use a loop muffler.

[Hasbro]

I would also retain the RBBmani and use that on a K24A2 rather than attempt to use the base RSX dual plane mani.

Even while moving, the CAI makes measurably more WHP and torque. The sRI is basically pulling heated air in, the wheel wells are not inlets, they are outlets for the radiator air flow, so placing a intake to suck in heated air isnt conducive to economy, the heated air will only raise cylinder temps.

No matter what header you have made, you must send it out to Swain Tech and have it properly ceramic coated, it reduces underhood temps TREMENDOUSLY!!!!

Make sure to use a loop muffler.

CAI. That's great. A little bit more tq and hp. With reference to this discussion, is there a particular brand or can I make a CAI that is as sufficient? I will be relocating my battery

So, basically keep it stock and save for a K24.

Lucid, 93 octane is about 10% more, give or take, so about a 4+ mpg increase would be needed to justify the compression mod. I don't know exactly how to figure this out but I'll bet it would be worth it! By the way,the hurricane didn't spike our gas here. $3.38 for reg. along with my shopping discount = $3.23.

[Fico]

Make sure to use a loop muffler.

loops are the shit! thats what i run!