Project 70mpg city car?
04-30-2006, 11:20 AM
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Project 70mpg city car?
Hello everybody!
In the next few months I'm going to be starting my new project, and I was considering a different kind of 'high-performance' vehicle... a mega-mpg machine.
So here's the thought I'm bouncing around, feel free to contribute any thoughts. My next project is going to be a very long term intense build. I've built plenty of bolt on cars, I want to really make something, and a mpg car sounds like a sweet challenge in the days of $3.00/gal gas.
So for a starting point we use a 1.3L 84-87 CRX HF. Very light to start at 1713lbs, and it can be stripped to just below 1600lbs when you keep an E-series motor and don't need alot of luxury features...like a heater.
The 1.3L is a CVCC equiped descendant of the motors used in the very first Civics. Stock they use a 3bbl carb to produce a wild 58hp while returning 52mpg city and 57mpg highway. What if we add modern performance decscended parts and techniques to extract as much efficiency as possible? If you can build a Civic with 500hp, doesn't it stand to reason that something equally impossible, like a 70, 80, or even 90mpg Civic might be possible?
So we take our motor, put super light rods, a knife edge crank, and high comp. pistons in it. We clean up the head, extrude hone the ports, and coat everything in thermal coatings so that a super hot lean mixture doesn't melt the pistons.
We also extrude hone the stock intake manifold, and make an adaptor plate to put a DPFI unit in place of the carb. It may choke a d-series motor, but it's probably a decent size for a 1.3L E-motor belting out less than 80hp. (Remember, a car that weighs less than 1800lbs with the driver in it could scoot just fine with say a 70hp motor and you only have to deal with the low duty cycle loss of 2 injectors rather than 4 when at low rpm/idle.
For management we use a Megasquirt ECU. They cost ~$350 unassembled and minus a case, carry an onboard MAP, use GM sensors, can run a wideband o2, and control a Ford EDIS for coil on plug ignition. Wire it up, add the EDIS for ultra-precise ignition (super lean hot combustion is just as volitile and unforgiving as ultra high hp-producing combustion) We then tune as lean as possible for <85% throttle, and max power for over 85%. Why max power? You need to get up to speed as fast as possible, then use the motor to maintain that speed.
For the car itself, strip it down, tin the interior, add racing seats, a harness bar/hatch brace (safety first). Lower it a little to minimize highway drag and give the car more lively handling, and add some really light skinny wheels. Maybe custom 13"x4" Volk TE37s. The ironic thing is the car might be really fun b/c the limits would be very low and attainable on the street, and if you did the suspension right and added an LSD, you could make the at-the-limit behavior fun.
So anybody have any thoughts or suggestions? I've got lots of time to figure it out as I get the feeling that finding a workable 84-87 HF rex may be a bit of a challenge.
-Aaron
In the next few months I'm going to be starting my new project, and I was considering a different kind of 'high-performance' vehicle... a mega-mpg machine.
So here's the thought I'm bouncing around, feel free to contribute any thoughts. My next project is going to be a very long term intense build. I've built plenty of bolt on cars, I want to really make something, and a mpg car sounds like a sweet challenge in the days of $3.00/gal gas.
So for a starting point we use a 1.3L 84-87 CRX HF. Very light to start at 1713lbs, and it can be stripped to just below 1600lbs when you keep an E-series motor and don't need alot of luxury features...like a heater.
The 1.3L is a CVCC equiped descendant of the motors used in the very first Civics. Stock they use a 3bbl carb to produce a wild 58hp while returning 52mpg city and 57mpg highway. What if we add modern performance decscended parts and techniques to extract as much efficiency as possible? If you can build a Civic with 500hp, doesn't it stand to reason that something equally impossible, like a 70, 80, or even 90mpg Civic might be possible?
So we take our motor, put super light rods, a knife edge crank, and high comp. pistons in it. We clean up the head, extrude hone the ports, and coat everything in thermal coatings so that a super hot lean mixture doesn't melt the pistons.
We also extrude hone the stock intake manifold, and make an adaptor plate to put a DPFI unit in place of the carb. It may choke a d-series motor, but it's probably a decent size for a 1.3L E-motor belting out less than 80hp. (Remember, a car that weighs less than 1800lbs with the driver in it could scoot just fine with say a 70hp motor and you only have to deal with the low duty cycle loss of 2 injectors rather than 4 when at low rpm/idle.
For management we use a Megasquirt ECU. They cost ~$350 unassembled and minus a case, carry an onboard MAP, use GM sensors, can run a wideband o2, and control a Ford EDIS for coil on plug ignition. Wire it up, add the EDIS for ultra-precise ignition (super lean hot combustion is just as volitile and unforgiving as ultra high hp-producing combustion) We then tune as lean as possible for <85% throttle, and max power for over 85%. Why max power? You need to get up to speed as fast as possible, then use the motor to maintain that speed.
For the car itself, strip it down, tin the interior, add racing seats, a harness bar/hatch brace (safety first). Lower it a little to minimize highway drag and give the car more lively handling, and add some really light skinny wheels. Maybe custom 13"x4" Volk TE37s. The ironic thing is the car might be really fun b/c the limits would be very low and attainable on the street, and if you did the suspension right and added an LSD, you could make the at-the-limit behavior fun.
So anybody have any thoughts or suggestions? I've got lots of time to figure it out as I get the feeling that finding a workable 84-87 HF rex may be a bit of a challenge.
-Aaron
04-30-2006, 12:07 PM
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Re: Project 70mpg city car? (ATX-Alchemist)
sounds like a fun project, working for the opposite mindset shall be interesting
You can a car real powerful with shitty mileage or a car with almost no power with superb mileage, its just combining the two which is hard.. kind of the way hondas are engineered
You can a car real powerful with shitty mileage or a car with almost no power with superb mileage, its just combining the two which is hard.. kind of the way hondas are engineered
04-30-2006, 01:51 PM
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Re: Project 70mpg city car? (neo_)
I think it would be fun. A challenging intellectual excercise for sure! Aftermarket stuff is so sophisticated these days, you can use it to out car-company the car conpanies! I think the goal for the whole project will be take the price of an Insight, divide it by 3, and that's the budget. Spend wisely and see if I can outmiser the hybrid.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by neo_ »</TD></TR><TR><TD CLASS="quote">It's going to be interesting on what you acheive. What octane are you going to tune it for?</TD></TR></TABLE>
93 octane while we can still get it
The key is going to be running obscenely lean ratios without melting the motor from the heat, so the highest available octane would be best.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by neo_ »</TD></TR><TR><TD CLASS="quote">It's going to be interesting on what you acheive. What octane are you going to tune it for?</TD></TR></TABLE>
93 octane while we can still get it
The key is going to be running obscenely lean ratios without melting the motor from the heat, so the highest available octane would be best.
04-30-2006, 02:38 PM
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Re: Project 70mpg city car? (ATX-Alchemist)
I would also be interested in a 1997 era HX explored for additional MPG potential, while keeping it commuter comfortable. A little heavier, but more available.
04-30-2006, 05:14 PM
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Re: Project 70mpg city car? (BigMoose)
ive been thinking the same thing. what about just upgrading the 89 hf motr? since it already has mpfi? the MPG is the same to start off with
05-01-2006, 05:05 AM
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Re: Project 70mpg city car? (HT Chaplin)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HT Chaplin »</TD></TR><TR><TD CLASS="quote">ive been thinking the same thing. what about just upgrading the 89 hf motr? since it already has mpfi? the MPG is the same to start off with</TD></TR></TABLE>
I would think a D15Z1 would be the way to go. Of course, if you want to keep the E-series motor, MPFI from the HF would probably be a better way to go than DPFI. DPFI was made more for low cost than either ultimate power OR MPG.
I would think a D15Z1 would be the way to go. Of course, if you want to keep the E-series motor, MPFI from the HF would probably be a better way to go than DPFI. DPFI was made more for low cost than either ultimate power OR MPG.
05-01-2006, 08:01 AM
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Re: Project 70mpg city car? (StorminMatt)
I was looking at the e-series motor mainly because it already comes installed in the 1st gen rex, and it is about 75-100lbs lighter than a D. In the 1g rex circles, the zc is the "big heavy integra motor." Keeping the E-series motor means that the car can be kept under 1700lbs. Honestly, if I decide on a d-powered car, I'll probably pick up a EF Civic/rex and install the 92-95 VX motor because the swap of an 88-up d-motor into an EA is that much of a PITA.
My main reason for looking at DPFI is that both the 1.3L and 1.5L e-motors came with downdraft 3bbl carbs, so the DPFI might be as easy as an adapter plate to physically install it on the motor (plumbing and wiring OTOH...) Option 2 is to pick up a weber DCOE mani and a set of 40mm TWM throttle bodies. Option 3 is to make a custom MPFI manifold, which is hard, but lets me use a GM t/b (has the right TPS), and have total control over vacuum ports, idle control mechanism, etc.
You know, it's funny. The more I think about this idea, the more I like it. It's always frustrated me that you can't really use your hot rodded car on the street to its full potential. I loved my old B16 hatch, which was tin canned, had a built head, and a coilover suspension... but I could only use it ~10% of the time. A really slow mpg-machine has an engine you can constantly thrash on w/o the attention of the law. Narrow, hard skinny tires so the limit can be easily reached, and the whole process should be a much more interesting challenge than making hp. That route is pretty well figured out.
-Aaron
My main reason for looking at DPFI is that both the 1.3L and 1.5L e-motors came with downdraft 3bbl carbs, so the DPFI might be as easy as an adapter plate to physically install it on the motor (plumbing and wiring OTOH...) Option 2 is to pick up a weber DCOE mani and a set of 40mm TWM throttle bodies. Option 3 is to make a custom MPFI manifold, which is hard, but lets me use a GM t/b (has the right TPS), and have total control over vacuum ports, idle control mechanism, etc.
You know, it's funny. The more I think about this idea, the more I like it. It's always frustrated me that you can't really use your hot rodded car on the street to its full potential. I loved my old B16 hatch, which was tin canned, had a built head, and a coilover suspension... but I could only use it ~10% of the time. A really slow mpg-machine has an engine you can constantly thrash on w/o the attention of the law. Narrow, hard skinny tires so the limit can be easily reached, and the whole process should be a much more interesting challenge than making hp. That route is pretty well figured out.
-Aaron
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05-01-2006, 08:24 AM
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Re: Project 70mpg city car? (StorminMatt)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StorminMatt »</TD></TR><TR><TD CLASS="quote">
I would think a D15Z1 would be the way to go. Of course, if you want to keep the E-series motor, MPFI from the HF would probably be a better way to go than DPFI. DPFI was made more for low cost than either ultimate power OR MPG.</TD></TR></TABLE>
The later HF motor made the same mpg, but already has a decent EFI set-up. The EV2 make 52mpg city with a lousy stinkin' carb. Adding ANY EFI setup with an onboard wideband and a really hard tune should be enough to see 60mpg, and if the motor was built to withstand the extreme temps of a very lean charge, maybe 70 is possible.
I'm really only looking at the 1.3L motors, as displacement is sort of the enemy here. More motor means more weight, more friction, etc. The key is light. A bigger stronger motor requires more brakes, a bigger trans, stiffer chassis, etc etc etc. The weight snowballs.
Basically I see three good options:
1) EA CRX, 1600lbs, EV2/EW3 motor w/~70 hp, probably the best for mpg
2) EA CRX, 1600lbs, same 1.3L motor w/ more aggressive intake, bigger cam, possibly IRTBs, ~100hp. MPG will be all in the <85%WOT tuning, but should still be stellar w/a killer soundtrack
3) EF CRX/hatchy, 1800ish lbs, 1.3L VX motor, maybe a better set-up but it loses a bit of the flavor IMO and puts the car in emmisions testing/inspection.
I would think a D15Z1 would be the way to go. Of course, if you want to keep the E-series motor, MPFI from the HF would probably be a better way to go than DPFI. DPFI was made more for low cost than either ultimate power OR MPG.</TD></TR></TABLE>
The later HF motor made the same mpg, but already has a decent EFI set-up. The EV2 make 52mpg city with a lousy stinkin' carb. Adding ANY EFI setup with an onboard wideband and a really hard tune should be enough to see 60mpg, and if the motor was built to withstand the extreme temps of a very lean charge, maybe 70 is possible.
I'm really only looking at the 1.3L motors, as displacement is sort of the enemy here. More motor means more weight, more friction, etc. The key is light. A bigger stronger motor requires more brakes, a bigger trans, stiffer chassis, etc etc etc. The weight snowballs.
Basically I see three good options:
1) EA CRX, 1600lbs, EV2/EW3 motor w/~70 hp, probably the best for mpg
2) EA CRX, 1600lbs, same 1.3L motor w/ more aggressive intake, bigger cam, possibly IRTBs, ~100hp. MPG will be all in the <85%WOT tuning, but should still be stellar w/a killer soundtrack
3) EF CRX/hatchy, 1800ish lbs, 1.3L VX motor, maybe a better set-up but it loses a bit of the flavor IMO and puts the car in emmisions testing/inspection.
05-01-2006, 10:38 AM
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Re: Project 70mpg city car? (ATX-Alchemist)
I have achieved all of your goals and more but used an easier route to obtain it. I bought a used 2001 VW tdi diesel with all the extras leather, moon roof, AC and yes a heater a nice comfortable car. I averaged about 45 mpg and I got the lower my fuel costs even more bug and started to look into home brew bio-diesel. Now I make my own bio fuel and have not stopped at a gas station in 6 months. It costs me about $.75 a gallon to make it and I will never go back. Dan
05-01-2006, 11:30 AM
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Re: Project 70mpg city car? (Dan Ruddock)
The TDi would eet every goal but one; being a fun project to piece together in my spare time.
My daily is 95 Accord, which may very well get traded for something newer if my rex project gets off the ground. I like the Jetta TDi (esp. the wagon), and would love one as a daily driver. My Insight-eater is just supposed to be my fun after work.
-Aaron
My daily is 95 Accord, which may very well get traded for something newer if my rex project gets off the ground. I like the Jetta TDi (esp. the wagon), and would love one as a daily driver. My Insight-eater is just supposed to be my fun after work.
-Aaron
05-01-2006, 11:51 AM
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Re: Project 70mpg city car? (ATX-Alchemist)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ATX-Alchemist »</TD></TR><TR><TD CLASS="quote">Insight-eater</TD></TR></TABLE>
Now that's something that you don't hear about everyday. Good luck on your project.
Now that's something that you don't hear about everyday. Good luck on your project.
05-01-2006, 01:21 PM
#12
GDD Lonely Krew
idea sounds great and i would love to hear the results. but i do have a question for you. since you seem to be quite knowledgeable on motors and the like, why would you choose extrude hone? very inaccurate and incorrect way to achieve not only high hp levels but proper efficiency. maybe there is something im missing but ive always heard that extrude honing is a thing of the past. care to shine some light on this one?
05-01-2006, 02:56 PM
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Re: Project 70mpg city car? (ATX-Alchemist)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ATX-Alchemist »</TD></TR><TR><TD CLASS="quote">My main reason for looking at DPFI is that both the 1.3L and 1.5L e-motors came with downdraft 3bbl carbs, so the DPFI might be as easy as an adapter plate to physically install it on the motor (plumbing and wiring OTOH...) Option 2 is to pick up a weber DCOE mani and a set of 40mm TWM throttle bodies. Option 3 is to make a custom MPFI manifold, which is hard, but lets me use a GM t/b (has the right TPS), and have total control over vacuum ports, idle control mechanism, etc.-Aaron</TD></TR></TABLE>
Regardless of whether you use an HF intake manifold or DPFI intake manifold, the fact is that neither will bolt right on - an adaptor or custom flange is the least that will be required to make either work. And neither one will be easier. So you might as well go for the better setup for this sort of project - the 1988-1991 HF MPFI manifold. Just because the DPFI manifold resembles the carb manifold that origianlly came with the car, this doesn't make adapting it any easier.
Regardless of whether you use an HF intake manifold or DPFI intake manifold, the fact is that neither will bolt right on - an adaptor or custom flange is the least that will be required to make either work. And neither one will be easier. So you might as well go for the better setup for this sort of project - the 1988-1991 HF MPFI manifold. Just because the DPFI manifold resembles the carb manifold that origianlly came with the car, this doesn't make adapting it any easier.
05-02-2006, 09:56 AM
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Re: Project 70mpg city car? (StorminMatt)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StorminMatt »</TD></TR><TR><TD CLASS="quote">
Regardless of whether you use an HF intake manifold or DPFI intake manifold, the fact is that neither will bolt right on - an adaptor or custom flange is the least that will be required to make either work. And neither one will be easier. So you might as well go for the better setup for this sort of project - the 1988-1991 HF MPFI manifold. Just because the DPFI manifold resembles the carb manifold that origianlly came with the car, this doesn't make adapting it any easier.</TD></TR></TABLE>
True, true either way will be much work. The adapter flange for DPFI is a very simple one though, as the footprint is very close to the stock 3bbl carb. Basically take one little piece of 3/8" aluminum, cut it, stud it to the intake mani, and bolt up the DPFI unit Beyond physically mounting it, I'm in the same boat either way, as I'm going to wire the car up for Megasquirt, and convert carb=>EFI no matter what set-up I use. (Unless I get really dumb and adapt Bosch CIS to it...)
For an MPFI manifold, a much easier solution is to crib one from an 85-87 Si as the bolt pattern is the same/close enough to work with. I'm really wondering if TWM 40mm IRTBs wouldn't be the best solution, as they have the most efficient flow with the least restriction. It seems like economy would just be a matter of tuning, as I'm indending to build the motor to withstand running lean anyway, and the IRTBs may save the pumping losses of the intake tract.
As for exturde hone, that was purely a by-product of considering the DPFI. This makes for a "wet" manifold, and honing it knocks down the bumps and imperfections that can "catch" the fuel droplets and start them pooling, esp. when the motor is cold.
Keep the thoughts coming! This is helping me figure this stuff out
Aaron Cohn
Regardless of whether you use an HF intake manifold or DPFI intake manifold, the fact is that neither will bolt right on - an adaptor or custom flange is the least that will be required to make either work. And neither one will be easier. So you might as well go for the better setup for this sort of project - the 1988-1991 HF MPFI manifold. Just because the DPFI manifold resembles the carb manifold that origianlly came with the car, this doesn't make adapting it any easier.</TD></TR></TABLE>
True, true either way will be much work. The adapter flange for DPFI is a very simple one though, as the footprint is very close to the stock 3bbl carb. Basically take one little piece of 3/8" aluminum, cut it, stud it to the intake mani, and bolt up the DPFI unit Beyond physically mounting it, I'm in the same boat either way, as I'm going to wire the car up for Megasquirt, and convert carb=>EFI no matter what set-up I use. (Unless I get really dumb and adapt Bosch CIS to it...)
For an MPFI manifold, a much easier solution is to crib one from an 85-87 Si as the bolt pattern is the same/close enough to work with. I'm really wondering if TWM 40mm IRTBs wouldn't be the best solution, as they have the most efficient flow with the least restriction. It seems like economy would just be a matter of tuning, as I'm indending to build the motor to withstand running lean anyway, and the IRTBs may save the pumping losses of the intake tract.
As for exturde hone, that was purely a by-product of considering the DPFI. This makes for a "wet" manifold, and honing it knocks down the bumps and imperfections that can "catch" the fuel droplets and start them pooling, esp. when the motor is cold.
Keep the thoughts coming! This is helping me figure this stuff out
Aaron Cohn
05-02-2006, 11:47 AM
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Re: Project 70mpg city car? (Buzzbomb)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Buzzbomb »</TD></TR><TR><TD CLASS="quote">Are you planning on doing anything to the underside of the car to reduce drag?</TD></TR></TABLE>
I'd like to keep digging as deep as I can to make the car better and better. Underside plates work really well, but you have to be very careful as you can go too far. I wouldn't be comfortable figuring out a tunnel system under the car w/o a wind tunnel model test, and flat plates can give your car flying Mercedes syndrome.
Look up Le Mans a few years back (the last year M-B participated), and check out how high those cars flew when the lip caught a bit of air and the flat bottom of the car turned the whole thing into a wing. Insert bad visions of coming over a rise on the freeway in a 1600lb car w/a flat bottom at 90mph (not that I would do such a thing on a public road
) I would make the news though if I shot a CRX 30ft in the air 
I'd like to keep digging as deep as I can to make the car better and better. Underside plates work really well, but you have to be very careful as you can go too far. I wouldn't be comfortable figuring out a tunnel system under the car w/o a wind tunnel model test, and flat plates can give your car flying Mercedes syndrome.
Look up Le Mans a few years back (the last year M-B participated), and check out how high those cars flew when the lip caught a bit of air and the flat bottom of the car turned the whole thing into a wing. Insert bad visions of coming over a rise on the freeway in a 1600lb car w/a flat bottom at 90mph (not that I would do such a thing on a public road
) I would make the news though if I shot a CRX 30ft in the air
05-02-2006, 01:47 PM
#17
GDD Lonely Krew
the flying crx sounds very interesting!!!
other than that, your bosch cis commnt really scared me. i know it was a joke but man that brought back my vw days!!! those efi systems are a PITA to work with. no honda owner would ever complain about engine management if they had to deal with one of those systems at one point.
other than that, your bosch cis commnt really scared me. i know it was a joke but man that brought back my vw days!!! those efi systems are a PITA to work with. no honda owner would ever complain about engine management if they had to deal with one of those systems at one point.
05-03-2006, 02:30 AM
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Re: Project 70mpg city car? (ATX-Alchemist)
ATX- Add a turbo, hear me out...
Yes turbos require more fuel to compensate for boost, but thats when you are boosting, its a well known fact that Turbochargers can increase fuel economy when crusing in vacuum because. the turbo spinning flows more air than the stock motor injests without a turbo. and the compressor also creates a swirling of the air which also helps with effciency. similar to teh swirling effect created by having only one intake vavle per cylinder open on Vtec_e motors
And with a High compression turbo motor with a free flowing exhuast, you could pretty much move of from a stop with barely any throttle, especially in a light car. less throttle depression= less rpms which ='s less fuel.
You could also cruise in 5th gear at under 2500rpms and still have enough TQ to keep the car moving at decent speeds.
Yes turbos require more fuel to compensate for boost, but thats when you are boosting, its a well known fact that Turbochargers can increase fuel economy when crusing in vacuum because. the turbo spinning flows more air than the stock motor injests without a turbo. and the compressor also creates a swirling of the air which also helps with effciency. similar to teh swirling effect created by having only one intake vavle per cylinder open on Vtec_e motors
And with a High compression turbo motor with a free flowing exhuast, you could pretty much move of from a stop with barely any throttle, especially in a light car. less throttle depression= less rpms which ='s less fuel.
You could also cruise in 5th gear at under 2500rpms and still have enough TQ to keep the car moving at decent speeds.
05-03-2006, 06:41 AM
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Re: Project 70mpg city car? (Boostage)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Boostage »</TD></TR><TR><TD CLASS="quote">ATX- Add a turbo, hear me out...
Yes turbos require more fuel to compensate for boost, but thats when you are boosting, its a well known fact that Turbochargers can increase fuel economy when crusing in vacuum because. the turbo spinning flows more air than the stock motor injests without a turbo. and the compressor also creates a swirling of the air which also helps with effciency. similar to teh swirling effect created by having only one intake vavle per cylinder open on Vtec_e motors
And with a High compression turbo motor with a free flowing exhuast, you could pretty much move of from a stop with barely any throttle, especially in a light car. less throttle depression= less rpms which ='s less fuel.
You could also cruise in 5th gear at under 2500rpms and still have enough TQ to keep the car moving at decent speeds. </TD></TR></TABLE>
I had been thinking of turbos, as most of the economy vehicles have them, since they can cruise with the turbo pumping the air into the motor using the exhaust heat. Especially since a lean mix make HOT exhaust that would spool the turbo quite well. Maybe a basic 4-5psi setup with no i/c and a good ignition control?
Yes turbos require more fuel to compensate for boost, but thats when you are boosting, its a well known fact that Turbochargers can increase fuel economy when crusing in vacuum because. the turbo spinning flows more air than the stock motor injests without a turbo. and the compressor also creates a swirling of the air which also helps with effciency. similar to teh swirling effect created by having only one intake vavle per cylinder open on Vtec_e motors
And with a High compression turbo motor with a free flowing exhuast, you could pretty much move of from a stop with barely any throttle, especially in a light car. less throttle depression= less rpms which ='s less fuel.
You could also cruise in 5th gear at under 2500rpms and still have enough TQ to keep the car moving at decent speeds. </TD></TR></TABLE>
I had been thinking of turbos, as most of the economy vehicles have them, since they can cruise with the turbo pumping the air into the motor using the exhaust heat. Especially since a lean mix make HOT exhaust that would spool the turbo quite well. Maybe a basic 4-5psi setup with no i/c and a good ignition control?
05-03-2006, 11:59 AM
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Re: Project 70mpg city car? (ATX-Alchemist)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ATX-Alchemist »</TD></TR><TR><TD CLASS="quote">I had been thinking of turbos, as most of the economy vehicles have them, since they can cruise with the turbo pumping the air into the motor using the exhaust heat. Especially since a lean mix make HOT exhaust that would spool the turbo quite well. Maybe a basic 4-5psi setup with no i/c and a good ignition control?</TD></TR></TABLE>
Well living in hot *** TX I would actually run an IC, sure you dont really need an IC at such a low boost level but its always safer. another thing you could do is run alcohol/water injection. and have it "mist" into the motor every now and then which has two benefits:
(a) Add extra octane which makes the fuel burn alot slower
(b) Cooling the intake air. making it even more dense which will give you better fuel economy (kinda liek driving at night)
Only problem is, you would actually lose power when you mist the motor with it unless you can figure out how to advance timing while spraying.
Well living in hot *** TX I would actually run an IC, sure you dont really need an IC at such a low boost level but its always safer. another thing you could do is run alcohol/water injection. and have it "mist" into the motor every now and then which has two benefits:
(a) Add extra octane which makes the fuel burn alot slower
(b) Cooling the intake air. making it even more dense which will give you better fuel economy (kinda liek driving at night)
Only problem is, you would actually lose power when you mist the motor with it unless you can figure out how to advance timing while spraying.
05-03-2006, 04:43 PM
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Re: Project 70mpg city car? (Boostage)
I'd rather look at water injection triggered by the AIT sensor than an intercooler. Saving the several feet of pipe will undoubtably make the whole thing more responsive. Megasquirt is easily capable of doing that. Even if its not, its open source code so you can teach it. I've been wondering about the Civic VX motor w/a turbo, triggering the VTEC at say, 2psi. 8v off boost, 16v on. *shrug* So many possibilities.
05-03-2006, 07:08 PM
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Re: Project 70mpg city car? (ATX-Alchemist)
Question, do u think High or low compression would work better? obviously High would give u better throttle response, but so would low with a very small turbo. I am actually doing the same thing you are doing, except my Chassis will be a 96-00 coupe with minor weight reduction. an HX motor or POSSIBLY a 3 stage vtec imported from Japan. btw have you seen this thread...
https://honda-tech.com/zerothread?id=1414454
bense is trying to do the same thing, build a very very fuel effcient motor with a little kick to it. its a LONG thread but you should read thru it.
https://honda-tech.com/zerothread?id=1414454
bense is trying to do the same thing, build a very very fuel effcient motor with a little kick to it. its a LONG thread but you should read thru it.
05-04-2006, 07:02 AM
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Re: Project 70mpg city car? (Boostage)
Wow! That's a great thread! I can't read it all right now, but I surely will! VTEC-e sounds verry interesting.
I'd like to stay high compression. Compression directly effects efficiency, and even with a turbo I'd like to see at least 9.5:1. 10.0:1 with 5psi boost would be a workable combo.
Things have gotten more complicated, and the gf is now gone with the car. (Don't date crazy girls) Good thing I live a block away from my shop I may have to switch this idea to an EF and make it more daily driverish. Don't want to get the thread off track, I'll post something about the gf nonsense in off topic later.
Modified by ATX-Alchemist at 9:40 AM 5/4/2006
I'd like to stay high compression. Compression directly effects efficiency, and even with a turbo I'd like to see at least 9.5:1. 10.0:1 with 5psi boost would be a workable combo.
Things have gotten more complicated, and the gf is now gone with the car. (Don't date crazy girls) Good thing I live a block away from my shop
I may have to switch this idea to an EF and make it more daily driverish. Don't want to get the thread off track, I'll post something about the gf nonsense in off topic later.Modified by ATX-Alchemist at 9:40 AM 5/4/2006
05-04-2006, 12:29 PM
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Re: Project 70mpg city car? (ATX-Alchemist)
Yes Vetc-e Engine's are awesome, IMO better than any other D series. I hear what u say about High compression, but Im set on lower compression. because the differnce is efficiency is minimal when you have a turbo, and I would like more overal hp and tq when I do decide to get on the throttle.
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