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I am planning to swap my 5th gen civic with either a H22A or B18C (could be a B18C1 or C4, as long as its an b18C) because they have an alright amount of power and dont get terrible mileage in the vehicles they come in. I was interested in what mileage you guys are getting with your swaps, I assumed the H22a would get worse MPG because its heavier and makes more power but in the forums Ive been seeing most people say about 23-27 for the most part, some saying as low as 18 and as high as 31. For the B18C to my surprise most people were saying 17-25. So I wanted to ask you guys here who have done either swap and figured out the MPG. mileage is my main concern because this is my daily and I drive about 200-300 miles a week and gas prices here in California are ridicules. So if you guys have any information on what mileage you get and would mind letting me know how hard you usually push your car that'd be awesome, thank you. Reply

 
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for mileage, you say... yeah... my original 2002 EX gets 46 MPG highway.

if you are going for MPG, keep it stock and do maintenance - should get you somewhere around 36+ MPG

 
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My integra with a B18B1 was pretty bad considering what it was (like 26 mixed, and the C1 is even worse).

D-series is by far the most fuel efficient in my experience. I wouldn’t bother swapping in your case. My ‘95 got like 38-39 mixed.

 
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Thanks for that. Do you think it would see much more of an improvement if it was in a fifth gen civic? (They weigh about 400-600 less than an integra) I've heard every 50 pounds of weight a vehicle looses increases mileage by 1%, so if it was in a car 400 lbs less than yours do you think it would realistically get 2mpg better? (26x8%=2.8) Also do you drive your car hard or do you drive more for economy?

And I want to swap it because I would like an engine that makes more than 125 hp with 106 tq and preferably has Vtec. I still want to get 25+ mpg so thats why i thought the H22a1 would be good, it makes about 187 hp and 158 tw brand new. But then I was considering one of the B18c's because they have about 170-195 hp and 126-131 tq, in the integra GS-R and type R it says it can get up to 25/31 27combined. But on most forums people with B18c swapped civic say they get low mileage usually around 21, And if the H22A can get better than that and not effect handling around turns than that seems like the right choice. I know the way someone driver has a great affect on what mileage you get and I dont push my vehicles around crazy hard (it happens occasionally tho) but I dont drive slow to get max MPG, I also live where theres a lot of hills which requires the car to be at higher RPMS. So maybe the H22 would get better mileage because it doesnt have to be pushed as hard to get the same hp?

 
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Have you done a H22 or B18C swap before? And which do you think would get better mpg? You seem to know a lot.

 
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I’ve helped with a B18 swap in another car. You probably wouldn’t notice much of a difference between the two. The prelude is slightly worse on gas than the integra but the prelude is heavier.

I have a friend with a B-swapped 5th Gen. He still gets only about 26 mixed.

It seems you’re prioritizing power over fuel economy. If that’s the case, get the B18. It's the best mix you'll get, even though it's still not great.

 
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Well I dont need a lot of power, I just want at least 150 hp, and the 5th gen civic si makes 125 hp the rest of them make less even in the 6th gens. I chose these two options because they are common swaps and make a good amount of hp for being in such a light car, Im just trying to decide which gets better mpg.

Why do you say go for a b18 for power? it makes less stock and i dont plan on doing any mods like a turbo or supercharging it.

 
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Do you think the weight difference between the H22a and B18c would make a difference in handling or do you think the 50, 100 lbs wouldnt make much of a difference around turns?

 
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No.

I forgot to mention that the H-series engines aren’t super compatible with the civic body’s unless you use an H2B conversion kit. H-series axles are slightly longer than B or D so they sit at an angle and snap under heavy load ie launching or super hard acceleration. H2B kit adapts to a B-series trans and axles so it fits much better.

 
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MPG? Power? Handling? what are you looking for in the end?!?

 
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Well I definetkly want to swap with one of these two engines. And MPG is the biggest concern but from what ive been hearing theres not a huge difference. The next thing that matters is how it handles on turns(where i live all the roads are very windy) and i belive the H22a with a H2B kit and transmisssion weights about 50-100 pounds more, and I was just wondering if you think that would effect handling?

 
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Yea everyone says getting a H2B kit is the best way to go with an H series engine and is what id do if i go with the H22A. could camber kits help get the tires back to even so the axles dont sit at an angle?

 
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I don’t think camber kits have any effect.