andrew7 Posted October 8, 2008 Share Posted October 8, 2008 I have been thinking of putting a turbo on my car, not for more hp on the top end but more on the bottom, where most of my driving occurs. The power is great from 7k rpm and up but getting from 2k to 7k feels well, slow and underpowered. I remember before I re-geared, the 4.11s worked great around town but I couldn't shift fast enough even with the paddles and cruising was painful. This is to find out from some of you if its worth while. I want to keep the pressure down 3-7psi, no intercooler, and keep my engine management stock. I was thinking about 20hp in the lower rpms might be enough. I was concern with overheating by constantly be in boost during highway cruise. I could post a general R1 motor dyno sheet but didn't want to give Mazda more anti-bec ammo when he seen 20hp at 2000 rpm, that thump you heard is him falling off his chair laughing. A member here or on another seven board works for a turbo rebuilder, (I see the pictures of thousands turbos laying around in my head don't remember where.) I want to keep it simple, it has worked great so far. A very small turbo,2 manifolds,piping and a generic FMU. My other choice is to drive it like a 16 year old with the engine revved all the time, scratch that, I'd look like a guy who doesn't know how to drive a stick. I'd appreciate any and all ideas from everybody, the BEC section was slow otherwise it would have been in the General section. Link to comment Share on other sites More sharing options...
slngsht Posted October 8, 2008 Share Posted October 8, 2008 Andrew, right about the part you said "that thump you heard is him falling off his chair laughing." I was actually laughing out loud. Not because of the 20 HP, but what you wrote :rofl: Link to comment Share on other sites More sharing options...
andrew7 Posted October 8, 2008 Author Share Posted October 8, 2008 WELL THERE'S YOUR PROBLEM :lol: it won't upload the dyno page....seriously Link to comment Share on other sites More sharing options...
slngsht Posted October 8, 2008 Share Posted October 8, 2008 give me a minute to make sure we're not out of disk space... brb Link to comment Share on other sites More sharing options...
slngsht Posted October 8, 2008 Share Posted October 8, 2008 try again, let me know if the upload works... had to make room for all those horses Link to comment Share on other sites More sharing options...
slngsht Posted October 8, 2008 Share Posted October 8, 2008 http://www.usa7s.org/aspnetforum/upload/973715981_R1_2004_vs_2007_hp.jpg Link to comment Share on other sites More sharing options...
andrew7 Posted October 9, 2008 Author Share Posted October 9, 2008 I found this one its RWHP, its over the top but notice the low rpm power. http://www.usa7s.org/aspnetforum/upload/1404102439_1Dyno.jpg Link to comment Share on other sites More sharing options...
scannon Posted October 9, 2008 Share Posted October 9, 2008 Something seems a little strange about the second dyno plot. My understanding is that the HP & torque curves only cross once and that is at 5,250 rpm. I have never seen a plot where the HP and torque curves cross twice. Neither of these occur at 5,250 rpm. The other thing is the plot shows negative torque from 2 - 3,000 RPM. What does that mean? Is there something different in the way motorcycle engines are dyno'd or perhaps in the calculations? Can someone enlighten me? As far as adding a turbo, it would have to be a very small one to produce boost down low with that small an engine. Being small, it would seem that it might actually cause a loss of HP at the top end due to restriction in the flow path of the intake. I suspect the turbo would be very inefficient at the very high rpm and produce excess heat. Skip Link to comment Share on other sites More sharing options...
slngsht Posted October 9, 2008 Share Posted October 9, 2008 Something seems a little strange about the second dyno plot. My understanding is that the HP & torque curves only cross once and that is at 5,250 rpm. I have never seen a plot where the HP and torque curves cross twice. Neither of these occur at 5,250 rpm. The other thing is the plot shows negative torque from 2 - 3,000 RPM. What does that mean? Is there something different in the way motorcycle engines are dyno'd or perhaps in the calculations? Can someone enlighten me? As far as adding a turbo, it would have to be a very small one to produce boost down low with that small an engine. Being small, it would seem that it might actually cause a loss of HP at the top end due to restriction in the flow path of the intake. I suspect the turbo would be very inefficient at the very high rpm and produce excess heat. Skip Skip, problem 1... Scale. Torque and HP scales are different. That's why the lines don't cross at 5252 Torque drop is quite possible depending on ramming effects (or lack thereof). Link to comment Share on other sites More sharing options...
andrew7 Posted October 9, 2008 Author Share Posted October 9, 2008 Yes Skip, I believe it would be a compromise, there always is. I might lose a little on top and gain a bunch in the bottom. Move the line up 20 hp just for discussion 150 to 170 doesn't mean anything to me but 20hp on the bottom is now double what I had. I believe the superbike engine works great for Jeff U. on the track, running around triple digit speeds and keeping the revs between 8k-12k rpm. The real world is a lot different, 3k-8k is normal with only a couple of times during a ride hitting the teens. This has more to do with the odd spacing of the tranny. First is very long...shift to second on your way toward 70 mph then the rest are all closely spaced. Cruise in sixth at 60 is 6k rpm in fifth its 400 rpm more, many times triple downshifts are required to get the engine over the 7500 line for get up and go. A properly spaced (wide ratio) tranny may be an alternative option to a turbo. All the graphs I've seen show more top end hp but its a steeper and more rapid climb, while the reliability goes way down. I'm still researching and listening for ideas. Link to comment Share on other sites More sharing options...
TurboBird Posted October 17, 2008 Share Posted October 17, 2008 I added a Hahn turbo kit to my Honda Blackbird BEC 4 years ago. It has terrific mid range grunt. I only street drive and have had no mechanical issues so far (average about 3k miles per year). My gearing/tire combo has the engine at 6k @ 70 mph. There is no boost at this speed unless you tip in with the throttle. Engine is otherwise stock. I run about 7 psi max boost, although Hahn says it can take up to 10. Performance with 7 psi is eye watering. Aquamist water injection system for charge cooling. Good luck Link to comment Share on other sites More sharing options...
ottocycle Posted October 18, 2008 Share Posted October 18, 2008 I do not have anything new to add to the turbo debate. I am a great believer in forced induction. If bottom end grunt is your preference I would look into a supercharger. You will not have the heat management issues you will have with a turbo and it will probably be easier to tune. I think the real issue with boosted BEC's is engine management. Since I re engineered my rear axle following the breakdown at Carlisle this spring I put in different axle and a taller rear gear which gave me better top end but lost me the peppy acceleration I had with the lower gears. I have been gathering the bits I need to build another Hayabusa engine and am an intercooler away from having all the parts (I have a line on one from one of our members), and am hoping to do it over the winter. Something to consider is this: The manufacturers went to a lot of trouble and expense to map the ignition and injection for our motors. One can piggyback onto the original system with a Power Commander or similar to boost the fuel rate delivered by the stock ECU (sometimes using larger injectors), but depending on the boost you run you will need to adjust the ignition curve. This bit confuses me as I understand the PC will only adjust fuel (I have a PC3 USB that only deals with fuel). Finding good credible data on how much boost you can have before altering ignition is difficult (I have yet to find it). I have not found a piggyback system that adjusts both fuel and spark. The other option is to use a standalone system and map from the ground up. The bottom line is this: To me there are two things to stick to. (1) I think it is false economy not to put an intercooler in a boosted BEC. (2) Budget handsomely for dyno tuning. A properly tuned simple system will be better than a badly tuned complicated one. Keep us posted with your progress, Cheers- Dermot. Link to comment Share on other sites More sharing options...
andrew7 Posted October 21, 2008 Author Share Posted October 21, 2008 I've been for researching the problem. The following kit is the only one available for an R1 in the US commercially. Its $6000, low boost and no opening the engine, I think its overpriced for what it is. I built the car so I could build that. Yamaha racing sells gearsets for different tracks but their priced about the same as the turbo kit. Dermot, I agree about the rear end ratio. My old 4.11s were great but driving 55mph and turning 7000 rpm for any length of time was terrible. If sixth was an overdrive I would have left them in. Yamaha's sport tourer the FZ1 might be another possibility. The crank and flywheel are 40% heavier, the stroke is longer, the gearing is wider spaced, and max torque is 2500 rpm lower. http://www.usa7s.org/aspnetforum/upload/1561819267_fp03.jpg http://www.usa7s.org/aspnetforum/upload/1039098992_146_0606_01_z+2006_yamaha_fz1+dyno.gif Link to comment Share on other sites More sharing options...
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