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Fuel sipper idea i've been kicking around


olie05

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Hey guys,

 

Lately I've been thinking about getting a late 90's tercel, and making it a gas saver car. I'm wondering though, what mods would help the engine consume minimum fuel?

 

Here are a few things i've been thinking about so far...

 

Polish the ports in the head (don't know if porting would help too)

Megasquirt it

Use water injection

Run low rolling resistance tires

Turbo?

 

About the turbo idea, I was thinking perhaps that would only work if i was starting with a smaller engine and trying to get it up to the power output of a 1.5. Otherwise I would just be cramming more air into the engine and having to dump more fuel in as well.

 

Although, i would be re using some lost energy in the exhaust, which would help efficiency. I'm somewhat confused in this area, so someone will have to educate me on that.

 

-Oliver

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(goldfish) I think the 96 and up came with a 5speed. That is what I was looking at.

 

rustrocket: i don't know what you were doing toting around a 400ci block in a tercel, but thats excellent fuel mileage, especially considering what you were hauling. The initial goal is 60mpg. I will either find the limit of the cars fuel mileage trying to obtain that goal, or set a new goal once that is obtained.

 

GraZee: the point of the turbocharger is to use some of the energy (heat) lost in the exhaust. I doubt that it would mean boosting to the point where the cooling advantages of water injection are needed. The water injection would be there to allow the engine to use less fuel. From what I have read an engine can be leaned with the use of water injection, and that is the reason why I mentioned it in the original list of mods.

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The turbo might help. I think it would depend on your driving conditions. I used to have a mid 90 tercel and I found that when driving 75-80+ it actually got bad gas mileage. When I kept it around 65 or less It got a lot better mileage. I think that it didn't have the power to keep going at those speeds in traffic and it was an auto. I know this isn't very scientific but hope it helps. This kinda goes with a question I ve had for a while. Can a turbo be used for better mileage?

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You might wanna research the 88-91 Honda CRX HF. This car was designed specifically for high fuel milage. This was the lightest version of the CRX and sought after by the swappers. The engine was an 8 valve (instead of 16) SOHC with very small intake runners and throttlebody, close coupled cat, and most noticable of all, a 5 speed tranny that is geared very far apart and has a very low (numerically) final drive. The engine redlined at 5k and the computer cut fuel at about 5200.

HTH

chris

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I know first hand about the CRX HF. In fact, check out my geocities page for a ZC swap into one. That car was awesome. The reasons why I am not thinking about that car is because I want a 4 seater. I want a car that i'm NOT going to want to go fast in. That is what the Z is for (for now at least)

 

great suggestion though.

 

I'm trying to get this thread to go more in the way of "what modifications increase fuel mileage." Lets hear it!

 

edit: i think i found my answer on turbocharging

http://fueleconomytips.com/2005/11/14/turbocharging-for-power-economy-cheap/

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HF crx was a wierd car. Roller rockers, multiport fuel injection, 1700lb curb weight, and only 8 valves-50 flywheel hp. Honda, what will they think of next?

 

I don't know if a turbo is really going to increase your mileage...If you are looking for engine mods that increase bsfc, look here:www.theoldone.com. Read all the articles he's got about swirl port combustion and "soft head" technology. You either declare shenanigans or come away feeling like you just joined a cult...Granted it's mostly honda stuff, but the theory shouldn't be limited to just that application. I'd love to hear what some old-timers like Grumpyvette or Dr. Hunt have to say about this guy and his ideas.

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I used to have a mid 90 tercel and I found that when driving 75-80+ it actually got bad gas mileage. When I kept it around 65 or less It got a lot better mileage.

 

I know the feeling, in my Civic hybrid if I go over 65(2000rpm) gas mileage suffers, going from mid 50's to about mid to high 30's.

 

I know first hand about the CRX HF. In fact, check out my geocities page for a ZC swap into one. That car was awesome. The reasons why I am not thinking about that car is because I want a 4 seater. I want a car that i'm NOT going to want to go fast in. That is what the Z is for (for now at least)

 

Yet again, I know this feeling too, in the hybrid, i NEVER even touch the gas pedal, its made for mileage, so I treat it that way. Even my 4 cylinder sentra is an economy car, but I tend to get on it quite a bit, it may have to do with the fact that the Z is not roadworthy now either. You have to take care of the need for speed somehow I guess.

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You should also considerater aerodynamics. With no other changes at all you could gain significant mpg by reducing drag. I know of a guy with a Cavalier who is undertaking this experiment right now. With nothing but modifications to reduce drag, he claims to have picked up about 8mpg on the highway.

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You could get a 325e. It was the same concept as an crx HF. Low redline, small combustion chamber, etc... it can get roughly 35mpg stock. With megasquirt or something to control injectors I could see 45 at the most. And you can pick them up for around $1k-1.5K. And its rear-wheel drive. But if you truly want the most fuel conservative 4 seater then a tercel or civic would be best. Or even a vw diesel. They get great gas mileage also. Like 50 if I remember correctly stock.

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Also a couple of notes on the CRX HF.

 

If you'll notice, the '87 actually got better mileage (54-57MPG) than the 88-91 body style (49-53mpg), according to http://www.fueleconomy.gov . 85-87 were the lightest, 88-89 heavier, and 90-91 heaviest. And by the looks, the 88-91 should be much more aerodynamic. Would the 200-300 lbs lighter really be 4mpg better on the highway in a less aerodynamic car, or did possibly some tighter emissions later on hinder the mileage?

 

Also a note on the engine design. The HF's peak torque was at right about 2k rpm which is where my '91 cruised 60mph at. The DX and Si's peak torque numbers were at ~4k rpm or thereabouts. They say an engine is most efficient at it's peak torque so i'm sure this is no coincidence. Something to consider if building a custom application would be to design the engine for peak torque at your cruising speed.

 

I always wanted to figure out how to slip a 20gal tank in my HF just so i could tell my friends that i only stop for gas every 1000miles or so. That would be too cool.

 

Later,

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