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Discussion Starter · #1 ·
I love E85. I have to drive 45 minutes each way to get it so I get about two months worth at a time. I've been using it everyday in my 2001 civic DX for over a year. I installed bigger injectors and the only problem is it takes longer to start... and the 25% loss of fuel economy. I'm tired of the loss of range.

I've been working on setting up an arduino to advance the timing. That should be done soon, but I don't think it's going to help much for mpg. I have some video on youtube ("civic timing signals" playlist) of me scoping the signals. Once I figure out what is causing the noise in the modified crank position signal I think it will be clear sailing to add a few degrees.

I tried to set up a mega squirt, but I got stuck and then I shelved it when I had kids. maybe I will need it when I raise the compression.

I want to raise the compression ratio of my d17a1 to get better fuel economy. It would be nice to have a little more power, but I don't really want anything that will get me in trouble. I have been reading a lot and two options appeal to me. One is to put in p29 pistons with a thick head gasket everything else the same. The zealworks calculator says that will give me 15:1, which seems radically high in any case and I don't know if the piston dome will even accommodate the head let alone the valves. I don't think it would be a good idea for me to try that project. It will end up making a mess in my shop. Nice work out, but not a great story.

The other option I see is to use d16 crank and rods and whatnot with the p29 pistons. zealworks says 12:1 with stock gasket. That doesn't seem radical enough for the trouble, but maybe I can get away with stock ecu? It seems like it will easily fit since the dome will be 2 mm lower than that of the pms pistons from the GX (I am assuming the GX uses the same head chamber shape).

I also like that using the d16 crank will lower the displacement. I used to drive a 1.6 DX and I got about 42 mpg on gas when my 1.7 DX gets 36.

I went ahead a bought a junkyard core d16z6 (on its way). maybe I can use those parts, or maybe i'll end up with a pile of abused and worn scrap. It will also be nice to have something to practice on before I take apart my daily.

I've seen some charts about how raising compression increases efficiency and I know it's not too magical, but it would be nice to at least try to take advantage of the fuel, and maybe the decreased displacement would get me closer to where I want to be.

any advice would be greatly appreciated! :bandito:
 

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My 05 EX d17a2 was getting around 40mpg average, 43 on the highway was easy even @ 80mph.

The pistons in my d17 sat nearly flush with the block, so using different pistons that have a higher compression height will make it sit out of the block some I am sure. Just cut the head down and use an adjustable cam gear if you want to increase compression.
 

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Discussion Starter · #3 ·
I didn’t think of cam timing, thanks. Do you mean increase static compression to increase efficiency by shaving head? I didn’t think you can get much that way. I can see how cam timing can change cylinder pressures, but I don’t think that will help me increase mpg unless it is to make more power at lower rpm.
 

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Discussion Starter · #5 ·
I’ve just been reading about what e85 can take. would 13.5 be good?. Taking .030 off the head would get me there with the d16 crank and p29 Pistons. One of the threads I read said only .008 could come off, but I have no idea.
 

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It's going to be a lot of work dropping a d16 crank into a d17. Keep the d17 crank and use different pistons or get custom ones made from CP or someone. Look into the GX pistons 01-03, they had the right wrist pin size and compression height, if you cut the head .030 you would be at 13. Still might want to clay the motor to make sure you have enough valve clearance. Probably fine because you don't have Vtec
 

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Discussion Starter · #7 ·
Ok I’ll look into custom pistons, maybe $500 for the set? Might be worth it when you add up the other costs. The gx pistons are very rare otherwise that’s what I would do.
 

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I have run e85 in a d16a1 that has about 12:1CR for years now - I can tell you that bumping up the compression will make you smile!
 

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if fuel economy is the goal, completely and utterly forget about E85.

even on factory flex fuel vehicles that can run E85, gasoline always wins for efficiency. E85 just means you can potentially make more power once you can tune for it.
 

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Discussion Starter · #11 ·
I’m interested in the environmental and political benefits. I want to make it as efficient as
Possible and take advantage of properties of the fuel.
 

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Discussion Starter · #12 ·
Hmm so i found out more about the timing gear on the crank. I got a z6 motor thinking it would have all of the swap parts, but I need the y8 timing gear since it has ckp sensor teath. It still works on the d17 even though it doesn’t have the split tooth?
 

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dont use e85 if you give a shit about emissions.

Get a new OBD2 spec catalytic converter and make the motor as stock as possible, minus perhaps slicing the head to add a little compression.

Else, pick your goal out, power, or fuel efficiency.

Saving fuel usage is technically saving more emissions.
 

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"environmental and political benefits"

Less fuel (gasoline) is better than a metric shit-ton of fuel (e85)


Not sure where you are going with this.
 

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My motor on e85 passes on the rolling dyno state emissions test with lower emissions than it did when it ran gasoline.

I user Tunerview and an Ostrich to emulate the ROM in a chipped PR4 ECU for tuning....OBD0.
 

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My motor on e85 passes on the rolling dyno state emissions test with lower emissions than it did when it ran gasoline.

I user Tunerview and an Ostrich to emulate the ROM in a chipped PR4 ECU for tuning....OBD0.
does the small bore of the D series allow you to run leaner than usual on e85? as in only 10-15% richer rather than the normal 25-35%?

I always got hammered by other tuners in my area that e85 wasnt for emissions in vehicles like GMs and Fords. more or less, just giving the consumer extra fueling options
 

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Discussion Starter · #20 ·
The environmental benefits are less carbon emissions, less human toxicity, and less direct contamination from spilling and fracking. Political benefits are a reduction of foreign interests that lead to war.

Corn ethanol is only the worst way to make it.

I’ve understood ethanol to burn cleaner because it has O2 in it. That’s why it is mandated in the US. Or is that propaganda? Burning more of it may lead to more emissions (of CO and hydro carbons) per mile if that’s what you mean, but maybe the motor can be optimized to not burn more or at least break even.

It’s a stabilizing economic force because it’s renewable.

I also find the prospect of optimizing for it fascinating.

I tried to pick up my donor motor today but apprenently the yard still hasn’t pulled it and it’s 200 miles away. Maybe I can find another one.
 
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