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Discussion Starter · #1 ·
So I recently bought a 97 EK that has a D16Y8 block and D15Y7 non v-tec head. I’m going to get a backup motor and trans from a salvage yard that shows to have 148k on them.

Im just a little skeptical on how the setup that’s in the car will turn out hence the back up setup. My question is kinda abnormal in that im not wanting to build the spare setup for HP or speed at all but for the best possibly fuel economy and reliability as this is my daily and need it to last as long as possible.

While the motor is on the stand what all can I do to achieve those goals ? I’ll also have the trans rebuilt just to be safe. I’m no mechanic but with good instructions and advice I think I can do a lot myself.
 

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93 4d lx, z6,ported, port matched, compression bumped, balanced, manual swap
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Find a shop that can dynamically balance the bottom end, use oem pistons that will get the compression ratio to somewhere between 9.8:1 and 10.2:1, port match a d15b7 intake manifold to the y8 head, have new guides put in and a valve job done, and find a new Yamada oem oil pump. Zfr6fgp plugs, send injectors out to be cleaned and flow tested, or purchase a set of flow matched rebuilds, good quality 91 or higher fuel. Serious debates about trans gearing with some saying stick with 4.25:1 ex gearing, some say hx, some say dx/lx but I think that all comes down to engine build and tuning. I'm currently running a z6 build that's on 4.25:1 ex gearing, logging 39.5 mpg combined, and I don't drive it gently since it's always chomping at the bit and trying to tear the tires off at every light despite recent attempts to tame the little beastie.
 

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Discussion Starter · #4 ·
Find a shop that can dynamically balance the bottom end, use oem pistons that will get the compression ratio to somewhere between 9.8:1 and 10.2:1, port match a d15b7 intake manifold to the y8 head, have new guides put in and a valve job done, and find a new Yamada oem oil pump. Zfr6fgp plugs, send injectors out to be cleaned and flow tested, or purchase a set of flow matched rebuilds, good quality 91 or higher fuel. Serious debates about trans gearing with some saying stick with 4.25:1 ex gearing, some say hx, some say dx/lx but I think that all comes down to engine build and tuning. I'm currently running a z6 build that's on 4.25:1 ex gearing, logging 39.5 mpg combined, and I don't drive it gently since it's always chomping at the bit and trying to tear the tires off at every light despite recent attempts to tame the little beastie.
39 mpg ?? That’s what I’m talking about !!!! Manual or auto trans ?
 

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93 4d lx, z6,ported, port matched, compression bumped, balanced, manual swap
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Manual or nothing for me, she will pull 5th from 35mph at 1500 rpm smoothly, and cruises down the freeway at 3500 rpm around 80mph at about 11% throttle. To be fair it's got extensive port work to maximize atomization, but the y8 head already does that pretty well, using a d15b7 manifold or even a d16z6 will help it do it lower in the rpm range so there is no need to wring it out getting up to speed.
 

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Discussion Starter · #6 ·
Manual or nothing for me, she will pull 5th from 35mph at 1500 rpm smoothly, and cruises down the freeway at 3500 rpm around 80mph at about 11% throttle. To be fair it's got extensive port work to maximize atomization, but the y8 head already does that pretty well, using a d15b7 manifold or even a d16z6 will help it do it lower in the rpm range so there is no need to wring it out getting up to speed.
thats the only things is mine is a auto. So I kno it’s not going to be the best
 

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93 4d lx, z6,ported, port matched, compression bumped, balanced, manual swap
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The increased efficiency at lower rpms will still help, my wifes 90 4 door lx still got decent fuel mileage with an automatic, even before the mpfi swap.
 

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93 4d lx, z6,ported, port matched, compression bumped, balanced, manual swap
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Road trip time! Unless you prefer auto. Also, if you prefer auto, look at a f23a4 auto swap, I bet if you baby'ed it ( not hard as the f23a4 makes MORE than enough off idle/low-mid torque to move a civic) it would average 45mpg with ac cranked to testicle freezing.
 

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Discussion Starter · #11 ·
Road trip time! Unless you prefer auto. Also, if you prefer auto, look at a f23a4 auto swap, I bet if you baby'ed it ( not hard as the f23a4 makes MORE than enough off idle/low-mid torque to move a civic) it would average 45mpg with ac cranked to testicle freezing.
I actually do prefer auto for ease of driving. But not so much for the mileage. I’ll look into that for sure
 

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A fully stock healthy d16y8 engine, even in automatic form, will easily get 35mpg or more.

01-05 civic fuel injector swap with necessary tophats will gain some mileage and low end torque. Same connector style, but has 4 holes rather than 1. They are physically shorter, and respond beter to slightly higher rail pressure.

Make sure the intake air temp sensor is not getting heat soaked. It is the ecu's tool for ignition timing. Colder, more timing. More timing within reason, more torque.

Make sure the coolant temp sensor for the engine/ecu is working proeprly. Too hot, it runs lean and drops power. Too cold, adds fuel and gains SOME power, but obviously looses economy.

These engines do not mind running slightly lean, but the lack of pwoer can hurt economy more than the slight lack of fuel.


The automatics can be fine with good maintenance. If the fluid was changed regularily and the torque converter is happy, and the lockup solenoid is working well, you get plenty of lockup at cruising speed.

A crappy non-functioning lockup solenoid can easily cause highway mileage to suffer as low as 25-30mpg.
 

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Discussion Starter · #13 ·
A fully stock healthy d16y8 engine, even in automatic form, will easily get 35mpg or more.

01-05 civic fuel injector swap with necessary tophats will gain some mileage and low end torque. Same connector style, but has 4 holes rather than 1. They are physically shorter, and respond beter to slightly higher rail pressure.

Make sure the intake air temp sensor is not getting heat soaked. It is the ecu's tool for ignition timing. Colder, more timing. More timing within reason, more torque.

Make sure the coolant temp sensor for the engine/ecu is working proeprly. Too hot, it runs lean and drops power. Too cold, adds fuel and gains SOME power, but obviously looses economy.

These engines do not mind running slightly lean, but the lack of pwoer can hurt economy more than the slight lack of fuel.


The automatics can be fine with good maintenance. If the fluid was changed regularily and the torque converter is happy, and the lockup solenoid is working well, you get plenty of lockup at cruising speed.

A crappy non-functioning lockup solenoid can easily cause highway mileage to suffer as low as 25-30mpg.
So the injectors from the 01-05 will work fine by just swapping them ?
 

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example of tophats

When someone says "so they just swap in?" I assume they read the key ingredient of the post and nothing else.

I probably have 1 or 2 sets of D17 injectors laying around.


But all you would need to do is measure the thickness of the top, subtract a small amount so the Oring can seal, and then figure out the actual height difference.



Do not assume the tophats I linked are proper ones. You will need to measure things up for yourself.
 

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My jeep 4.0 had single hole injectors. They were for all intents and purposes, clean and working fine. I installed Bosch 12 hole injectors. FAR better idle quality, partial throttle driving, and average gas mileage went up a good chunk.

That doesnt mean the injectors themselves are responsible. It means that overall the atomization made everything easier to work. It lets a weak ignition have a better chance at lighting the mixture. It lets lower compression still have a chance at creating a good cycle, etc...


My jeep went from averaging 11mpg over the course of 500 miles to around 17mpg in the last 55-60 miles. I will not call it the injectors alone. But I bet I could have gotten closer to 17mpg if I had EVERYTHING else running perfect.

Good atomization just makes everything easier to work.


Now Im thinking of finding a good matching set of 12hole inejctors for my mercury.
 
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