D15, D16, D17 and Mini-Me swaps
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By noname87
#302836 while im in the process of building an n/a d16z6 im gonna rock the d15b8 until its done. trying to get the best mpg out of it. the intake mani and TB are f'n tiny and was in the process of finding a 1.6 or bigger 1.5 mani and TB, other than a full exhaust and intake is there anything else anybody can think of to get better mileage, i wanna see how much i can get out of this gutless wonder
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By FG2_Andrew
#302858 Keep everything stock, remove all weight you can, keep tires inflated, oil change, run with windows up to reduce drag.
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By suspendedHatch
#302909 Less air in the engine means less fuel burned. If you bolt on parts that allow more air in, especially on an ECU that isn't tuned for it, you will hurt mpg.

Increasing an engine's power increases mpg only under certain circumstances. If you live in a hilly area, and find that you are heavy on the throttle from frequent stops, then increasing the engine's output helps you get up to cruising speed faster. The point after you've backed off the throttle is where you achieve your best fuel economy.

An engine requires all of it's hp to accelerate and then only 8-12hp to cruise. If you've increased the output beyond what is necessary you burn excess fuel while cruising.

If you have a 1.5 liter 8 valve engine and find that you frequently require lots of throttle, your best bet is to get a small turbo. NOT AN N/A SETUP. You boost under acceleration but under cruise you're at atmospheric pressure. Turbo setups are complex and expensive, so if cost savings is your only goal, it will never make sense. But if a mix of performance and economy is what you're after, then you can piece together a setup from late eighties junkyard parts and create quite a little monster. Ultimately, it's the quality of the engine management and tune that will determine your success or failure.
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By TrailerTrash
#302911 lighter wheels and keep it under 2,000rpms
Last edited by TrailerTrash on Thu Apr 26, 2012 3:50 am, edited 1 time in total.
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By Wicked
#302913 HAHA you can change all kinds of things but in the end unless you get the head ported you wont be able to utilize the bigger TB/IM/H/E. If anything it will reduce back pressure which will cause more harm then good. Plus your still limited to 8 valves. Its most likely the reason why there are NO aftermarket parts rated for these motors. I have one too they are quite the oddball motor. What you could try is swapping the head with a B7 just to get 16 valves and bigger TB/IM/H/E. AFAIK some d15b8's have all 16 valve reliefs on the pistons, I know mine does. So it should be just a simple swap of the head as everything bottom end should be the same as a B7, I was gonna do this to get some more power from it until I drop my bigger motor in as well, but I can't justify spending the money on this motor.
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By noname87
#314302 the guy i bought this car from said he had a d15b7 laying around that i could have for cheap. the gearing in this trans is ridiculously long but it gets GREAT fuel mileage. he said that the b7 will work with the b8 ecu but im pretty sure just going off of research that he's wrong. i like having the oddball engine and the ppl that run around here in lincoln that are in the honda scene think i should keep it too. just throwing around ideas for a little more power
By jhicks
#314324
suspendedHatch wrote:Less air in the engine means less fuel burned. If you bolt on parts that allow more air in, especially on an ECU that isn't tuned for it, you will hurt mpg.

Increasing an engine's power increases mpg only under certain circumstances. If you live in a hilly area, and find that you are heavy on the throttle from frequent stops, then increasing the engine's output helps you get up to cruising speed faster. The point after you've backed off the throttle is where you achieve your best fuel economy.

An engine requires all of it's hp to accelerate and then only 8-12hp to cruise. If you've increased the output beyond what is necessary you burn excess fuel while cruising.

If you have a 1.5 liter 8 valve engine and find that you frequently require lots of throttle, your best bet is to get a small turbo. NOT AN N/A SETUP. You boost under acceleration but under cruise you're at atmospheric pressure. Turbo setups are complex and expensive, so if cost savings is your only goal, it will never make sense. But if a mix of performance and economy is what you're after, then you can piece together a setup from late eighties junkyard parts and create quite a little monster. Ultimately, it's the quality of the engine management and tune that will determine your success or failure.



i agree with this guy to an extent. my old ef hatch got around 34 mpg with the stock intake. i put a slightly bigger TB on and a short ram air intake and that mpg increased to 36-38.

i do agree that the more air, the more fuel has to be used. an engine should keep a certain fuel to air ratio.
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By FG2_Andrew
#314337 when i had my b7, it hurt me more using a larger TB and IM because there was more air being forced up than my motor could handle and the excess was fighting for somewhere to go.
By jhicks
#314345
EH2_andy wrote:when i had my b7, it hurt me more using a larger TB and IM because there was more air being forced up than my motor could handle and the excess was fighting for somewhere to go.


ive never tried a larger IM. lol. im too cheap.
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By noname87
#314479 Ok. Ya I thought about a bigger tb but wasn't sure. Would a higher flowing fuel pump help if I went with a couple upgrades? I mean fuel injectors can only flow so much but I guess I'm not sure. Even at 30 to 35 mpg with upgrades it's ok.
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By noname87
#314480 And would the b7 work with the b8 ecu? Never got a for sure answer on that