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1.5L turbo swap?

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    1.5L turbo swap?

    Now I know you're probably thinking I'm an idiot for entertaining this idea, but bear with me for a second as I throw down some background information:

    My last car was an EF hatch, and I had swapped in a d15z7 (three-stage VTEC) motor. On the bone-stock motor with nothing more than a tune, I was getting about 150 at the wheels and 55mpg. Before it was rear-ended and totaled (ironically, by the same CB9 I have now), I was assembling a turbo setup to increase efficiency by eliminating pumping losses. A/F ratios of 25:1 with a heavily stratified charge, boosted for zero pumping losses, would net around 70mpg and ~230whp in the civic. (these are VERY realistic numbers, by the way)

    So I've got this entire setup sitting in the back of my garage next to the J30A4, and its been bugging me; I seriously am considering dropping it in the CB9. I know there will be a loss of efficiency due to the weight penalty of the wagon, but It will be loads better than what I'm getting now.

    So, feedback! Let me hear what you've got.

    #2
    In addition to the static weight of the two vehicles you're comparing, also consider the additional unsprung weight of the wagon over even a sedan/coupe. The brake rotors are an inch larger in diameter as well as 4mm thicker. The caliper is also significantly heavier. The rear subframe is more beefy and the 4 rear lower control arms are solid pieces of steel instead of the stamped steel usually found on the sedan/coupe. The wheels are heavier and the tires are heavier and the knuckles at all four corners probably weigh another 8 pounds each over what a Civic's knuckles weigh.

    I don't mean to discourage you at all. I just mean to show you that the losses in efficiency won't be directly proportional to the difference in weight alone. The wagon is just built to be beefy and this will show in a build attempt to use a low-displacement alternative to achieve fuel efficiency.

    What evidence do you have of someone achieving those types of numbers?
    My Members' Ride Thread - It's a marathon build, not a sprint. But keep me honest on the update frequency!

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      #3
      I also agree on the weight. Aerodynamics will also come into play here. I'm no ME so I can't comment on pumping losses. I do know that it won't be exactly zero, there will be some loss.

      You will be putting your foot down a lot more because of the extra 7-800 pounds that the CB9 has over an EF Civic hatch. You seem to be good with numbers. If you have a dyno of your motor, you can get a feel for how it will operate in the real world. I hope that the D15 has good low end otherwise it will be a slug in daily driving AND you'll be forced to rev it higher.

      YouTube Clicky!!

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        #4
        25:1? Have you ever tuned anything? You could however tinker with the EGR system to achieve the same compression with the matching amount of fuel 25:1 would require. Weight only matters for city driving or when you're accelerating. Highway driving the mass doesn't matter, aero does. My car normally gets 32-35 mpg. I've done multiple road trips across the country with an extra 1000lbs in it and I still got 35 one time. And that was with an H22A. Small engines in big cars is the key to gas mileage. Dodge Dart weighs 3300lbs, has a 1.4 turbo, get 41 mpg. That's also the case with a few other cars. But to me this sounds like just another "what if" thread.
        '93 H22A 5SPD SE - MRT - DIY-Turbo Sizing

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          #5
          Agreed. & I wouldn't want to put 6 people in the car with luggage in the trunk, that's another 1200lbs+. It may not move...

          Comment


            #6
            haha wow I didn't really expect that kind of response.

            Yeah the tuning is crazy for these motors, and while 25:1 sounds pretty insane, you should probably look up the "stratified combustion charge" that I referred to. That's not the compression ratio, by the way, that's the A:F ratio.

            Basically, the motor has two cam profiles and three cam stages, the first of which is a high-swirl setup that allows for the ridiculous A:F ratios. Consequently, the torque curve is nice and beefy low down in the rev range, but then again, That was for a 2000 pound car.

            Still, whatever the weight penalty is, I'm positive it will be a performance and efficiency increase over the pitiful f22 in there now.

            As for numbers, I know the EF Cd is .32, which is exactly the same as the CB9 and my usual cruising speed of 65@~3kRPM is in the sweet spot for the D motor's efficiency.

            As for daily driving, the torque curve is nice and flat, with 120 available at 2k, building up to about 190. So not a ton of torque, but still better than the F22A1 over the entire usable RPM range.

            So, ye naysayers, what do you think? I've already got most of the important stuff, all I'll need is a donor car to get all of the physical mounts worked out.

            The other idea for hypermiling swap is the J35A7 with the variable cylinder management.

            Comment


              #7
              and it's a proven build, look for FullRacePhil on ecomodder.com, he's got the details of his build. I actually got a hold of the maps for his car from locash so I've got a pretty good starting point.

              Comment


                #8
                Do it up!

                Which transmission do you plan on using?
                Originally posted by deevergote
                These cars will never be the best at anything, but they're pretty damn good at everything.

                92ex CB7<-SOLD 93ex CB9shiftingshift73C10

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                  #9
                  Sounds like you should have no issues then. As long as the engine is working in overtime constantly and cam profiling is easily managed for the new added weight. I didn't even know reliability could come with a 25:1, but I'm not educated enough to know, first I've heard of 25:1.

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                    #10
                    Make a build log already dude...you know what your doing.

                    It sounds like you are using the turbo to tell your motor how to breath. I want to do that as well with a VGT. I have to finish other projects first. So I will be following this.

                    Also 1000lbs should only knock off a couple of mpg's, it won't be like hitting a brick wall. What EMS are you using?

                    YouTube Clicky!!

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                      #11
                      If this engine is indeed putting down 200whp than you should have no problems moving the CB9. However with the added weight you can expect the MPG to drop a bit. looking forward to seeing this in action.

                      Is the D15 direct injection?

                      I'm just wondering how you are planning this stratified combustion charge? A Homogenous A/F mixture is the only way in most of the Honda engines that I have worked on. They are port injected vs direct injection. After reading up on this for a while I was under the understanding that direct injection into the combustion chamber is required for stratified combustion.

                      I believe the HP and the possibility that higher MPG are attainable. It's the 25:1 AFR's that have me scratching my head.
                      Last edited by GhostAccord; 04-17-2014, 04:33 PM.
                      MR Thread
                      GhostAccord 2.4L Blog

                      by Chappy, on Flickr

                      Comment


                        #12
                        The cost of the adapter to make a D series motor fit a F transmission would probably cost more than just finding another EF hatch shell, but it would definitely be a cool project. Make sure to take lots of pictures and share.

                        Comment


                          #13
                          Not sure if there are any D2F kits. I would imagine that this would have to be a custom adapter job. Not sure how much it really involves though. I'm not all that familiar with the D series block-transmission bolt pattern or the axle, shaft/spline layout.
                          MR Thread
                          GhostAccord 2.4L Blog

                          by Chappy, on Flickr

                          Comment


                            #14
                            I only skimmed most of the replies, so pardon me if I missed something.

                            motohead623, can you weld? If so, it won't be as crazy of a project.
                            An adapter plate to use an Accord or Prelude transmission would probably make things easier. There ARE some cable-shifted B series transmissions out there that you could probably make use of as well (not sure what from... I believe it was drummersteve that was telling me about them a while back.) Chances are you'd need to use custom axles if you went that route, though.

                            It'll be a lot of work to get it in there and working, but honestly, probably no more costly than building and boosting an F or H. If you're still going for power and efficiency in the CB9 (PROBABLY not a good choice for efficiency... ) then the D is still your best bet.
                            Most people that ask this question are clueless. I'm glad to see someone who has an idea of what they'd be getting into! If you do it, I'd love to see a detailed build thread. You'd be the first D series powered CB in existence, I think!






                            Comment


                              #15
                              Originally posted by motohead623 View Post
                              haha wow I didn't really expect that kind of response.

                              Yeah the tuning is crazy for these motors, and while 25:1 sounds pretty insane, you should probably look up the "stratified combustion charge" that I referred to. That's not the compression ratio, by the way, that's the A:F ratio.
                              I know what you were talking about. I assumed you wanted to run so lean as to save on fuel. But the exhaust temps you'll end up with will likely melt your valves, if not not your manifold or whatever else. That's why I recommended properly using the EGR system so on partial throttle, when the intake charge is less dense, you can fill some of the volume with inert exhaust gas causing your effective compression to increase and therefore get more power out of the combustion.

                              Originally posted by GhostAccord View Post
                              Is the D15 direct injection?

                              Nope

                              After reading up on this for a while I was under the understanding that direct injection into the combustion chamber is required for stratified combustion.

                              Yep

                              I believe the HP and the possibility that higher MPG are attainable. It's the 25:1 AFR's that have me scratching my head.

                              MELT ALL THE THINGS!
                              And if it means anything to you I graduate with my BSME in 29 days. I specialize in fluid mechanics, heat, and IC engines. I've been working as an engineer for Chrysler for 3 years. My first year I did a lot of development on the performance tunes for the Fiat Abarth 1.4T, which is also in the Dart. My second year I did the engine and suspension development on the Viper using MoTeC and our in house controllers. When I was a teenager I built a 98 Neon with a 2.4 out a Caravan, added boost and nitrous. I've also swapped a few different engines in my day and before college actually worked as an engineer for Manning Applied Technologies doing a lot of thermal systems designs and fluid mechanics.

                              I don't know anything about you except I think you're a fellow engineer, but I've learned over the years a lot of what you learn in early thermo, heat transfer, and fluids doesn't work in the real world. The biggest red flag I have on this is the A/F you're wanting to run. Even modern DI engines only run close to stoich and the only reason to run over is to keep cylinder pressures high. But stuff get's hot super quick. You're basically wanting to run the engine continually on notrous with no tune. I'm not saying I know everything it's it's very likely you are onto something I don't know about, so I'm interested to see what else you have to say and I'm on board to help in any way.
                              '93 H22A 5SPD SE - MRT - DIY-Turbo Sizing

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