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Old 01-28-2010, 11:25 AM   #1 (permalink)
Si engine and trans
 
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CRX Si/HF - '90 Honda CRX HF
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Long time Lurker and semi-hypermiler...

And like the title says, I've been looking at this site for over the past year. I've never had to register because I never had any other questions, except until now...

Ever since gas hit over $4 a gallon down here in Houston, I sold my 22+mpg getting 1985 Crown Vic, why? I just couldn't squeeze any more MPG out of her. That's when I bought my CRX HF. Now, at the time when I bought this little rocket of fun, it had (still does) the entire Si driveline. I didn't know jack about Honda's and I probably would have waited for another CRX (perhaps with the HF engine and trans), but I'm glad I didn't as this car is super clean, and I have yet to find another one like it. Now on to the equipment...

The engine in the CRX is actually a ZC (d16a6) with the Si trans (3500 @ 70mph), however I am still convinced that I can get 50mpg out of this car. It has 2 1/4" exhaust (no cat), HKS Super sport exhaust. The car is actually extremely quiet, and does not sound ricey at all. It also has Neuspeed Race springs accompanied by Tokico Illumina 5-ways. A home-made fender well CAI and a Megan header are the only items under the hood.

So far, I have made some fog light block off plates, and I made an under the front bumper pan to block air from being trapped in there. I made it like the one on the Prius or whatever Japanese car they were testing it on.

Any who, my question is since I have an HF, but it has the Si driveline, what should I list my car as in the Eco-garage? Thanks guys for all the help in the past as well as the future!!

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Old 01-28-2010, 12:16 PM   #2 (permalink)
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I would list it as an HF, and say it has the Si components. Or...you could just list it as an Si. The latter may actually make more sense.
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Old 01-28-2010, 12:56 PM   #3 (permalink)
Si engine and trans
 
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Quote:
Originally Posted by MadisonMPG View Post
I would list it as an HF, and say it has the Si components. Or...you could just list it as an Si. The latter may actually make more sense.
Thanks man... I'll probably list it as an HF with Si driveline.

Oh and BTW, if I run the car has hard as possible (meaning hauling ass everywere I go) the worst this car has gotten is 31MPG. If I drive sensibly, but still spirited, I can usually get between 34 - 35 MPG. The absolute best I have gotten is 40.5 MPG, however that was with out any instrumentation telling me about engine load, MPG's, nothing. I have since connected up a vacuum gauge (liquid filled) and I am now driving about 90% by the gauge. I try to keep it at 15" of vacuum or greater. I rarely ever let it go under 10" and if I do, it's only because I'm being nice to the person behind me. Otherwise, grandpa's are passing me by....

So far after having the vacuum guage hooked up (this was with out my fog light blockage and my front bumper pan) I have managed to hit 38MPG again (doing 70mph+). Now I have my fog light holes being blocked and my front bumper pan in place and I'm hoping to hit 41 - 42 MPG????

My ultimate goal is do be able to hit 50MPG will still being able to go ~70MPH on the freeway. What's funny is here in Houston, 70mph on the freeway is slow. So I'm still gambling with safety a bit, but I don't care, they can go around me....
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Old 01-28-2010, 01:23 PM   #4 (permalink)
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Hmm, a ZC and the D16A6 are actually quite different. The ZC is a DOHC motor making 130hp, with the A6 being a SOHC making 108. I have a completely stock '91 CRX Si, save for Koni shocks and get right at 40mpg. I've been thinking of installing the HF 5th gear in my transmission to lower the revs in mine. Other than that I can't tell you much since I don't really know hondas either.
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Old 01-28-2010, 01:29 PM   #5 (permalink)
Si engine and trans
 
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Quote:
Originally Posted by tpwalsh View Post
Hmm, a ZC and the D16A6 are actually quite different. The ZC is a DOHC motor making 130hp, with the A6 being a SOHC making 108. I have a completely stock '91 CRX Si, save for Koni shocks and get right at 40mpg. I've been thinking of installing the HF 5th gear in my transmission to lower the revs in mine. Other than that I can't tell you much since I don't really know hondas either.
There are many variants of the ZC and one of them is a SOHC Non-VTEC version, which is exactly the same as the d16a6 with a slightly different cam. The ZC SOHC Non-VTEC engine is rated at 118 hp (US). My block is stamped with the ZC stamping. I will post pics of this car soon....

Oh and BTW, I know a few guys who've done the 5th gear swap and were disappointed. The didn't get any more MPG and the drop from 4th to 5th is huge now and is not really very beneficial. If anything, swap the entire trans to the HF trans. That will save more than just the 5th gear swap....
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Old 01-28-2010, 01:31 PM   #6 (permalink)
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Ah, another ecomodder stuck with a ricey engine. I have to deal with a torquey 98 Civic EX coupe that makes 127HP... Your motor makes 108 I think, so you have a bit of an easier path but we have the same final drive ratio (4.25) with my 5th gear at .702 and yours at .771. What a bummer that you don't have the original D15B6, or especially that HF transmission.

Looking at my fuel log you would see that the lower 50s MPG is attainable with a more powerful and heavier car than yours, but I never really go 70 unless I'm rolling down a hill. Based on my experience and what I've read, I think your goal is possible, but it's a lofty goal and you will have to make some drastic changes to any or all of the following: your driving style, your engine/trans, aerodynamics, LRR tires. Ditch the CAI and get that engine breathing some hot/warm air right off the exhaust manifold - that should help a bit too.

Personally I'd list it as an Si. That would make you look better as an Si with that lightweight HF body versus making your results look worse among genuine HFs, but more power to you if you can beat them out with your car.

Good luck and welcome to EM!
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Old 01-28-2010, 02:00 PM   #7 (permalink)
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I think 50mpg is attainable, but tough as well. I should qualify my average 40mpg. I drive 99% on the highway, and there is very little stop and go in the little city driving I do.

I would also list it as an Si, the weight difference doesn't make that much of a different, certainly less than the drivetrain.
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Old 01-28-2010, 02:10 PM   #8 (permalink)
Si engine and trans
 
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Quote:
Originally Posted by Wonderboy View Post
Ah, another ecomodder stuck with a ricey engine. I have to deal with a torquey 98 Civic EX coupe that makes 127HP... Your motor makes 108 I think, so you have a bit of an easier path but we have the same final drive ratio (4.25) with my 5th gear at .702 and yours at .771. What a bummer that you don't have the original D15B6, or especially that HF transmission.

Looking at my fuel log you would see that the lower 50s MPG is attainable with a more powerful and heavier car than yours, but I never really go 70 unless I'm rolling down a hill. Based on my experience and what I've read, I think your goal is possible, but it's a lofty goal and you will have to make some drastic changes to any or all of the following: your driving style, your engine/trans, aerodynamics, LRR tires. Ditch the CAI and get that engine breathing some hot/warm air right off the exhaust manifold - that should help a bit too.

Personally I'd list it as an Si. That would make you look better as an Si with that lightweight HF body versus making your results look worse among genuine HFs, but more power to you if you can beat them out with your car.

Good luck and welcome to EM!
Thanks for the welcome, and trust me, I know there's much more to do and try and experiment with... I am going to make an entire under car belly pan, and I'm doing it very, very soon. I'm doing more aero mods, and probably getting LRR tires soon as well. I want to do something with the rear of the car now, but I need to read more....

Speaking of warm-air intakes, I removed the coolant lines that used to run through the throttle body and IACV and I simply looped it back to the engine. I should probably hook this back up. Also, I am not running the IACV, due to the fact I could not make the car idle properly without removing it.

So, I should be able to hit 50MPG, cool... I am trying like hell to do it while having a car that run's a very low 15 second 1/4 mile. BTW, I don't know how I ever drove with out the vacuum gauge, I love it!!
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Old 01-29-2010, 09:12 AM   #9 (permalink)
Si engine and trans
 
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CRX Si/HF - '90 Honda CRX HF
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All right, I'm at 240 miles at half tank. That's the best I've ever seen. I wish this thing had the larger tank, as it's only 10.6 US gallons. This is not really coasting that much, no EOC at all, no P&G, just keeping my distance and trying not to go above 70mph.

I want to see 300 at half tank. So does the warm air induction really help and by how much typically, 1 MPG, 2 MPG?

Also, what about weight? I have 53lbs. worth of stereo equipment in the car as well, however I like to hear my music, and that means the entire sound spectrum. SO I don't want to ditch my 12w3, however I might make a lighter box for it, and maybe cut the weight in half....
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Old 01-29-2010, 11:50 AM   #10 (permalink)
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I wouldn't stress over your audio system. Best thing you can do for mileage is slow down. Drive country roads where you can keep your top speed down, or just ignore the fast traffic and let them go around you. My 2 liter cars average 26 mpg at 72 mph, and 38 mpg at 60 mph.

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