subtle_driver Posted September 29, 2009 Share Posted September 29, 2009 hey guys, my daily driver 240z has an l24 with a stock bottom end, with 215 psi compression with maxima head and stage 1 cam from schneider with spring kit. i make 140hp to the wheels. i have z theropy su carbs, and i made my own 3" exhaust. but they lean out at 4-7thousand rpms even with sm needles. i know this becuase i have a wideband hooked up. I love the ease of tuning and low maint. and the very high reliability of the SU carbs. I just want more power. i know i can make some more power with different carbs or intake. I want to get some tripple carbs or an efi itb setup. but i don't want to spend much more than $1,000 or so. If someone was selling a tripple carb set used for $600 i would buy it. But i don't know what is the most user friendly carb set, that i can get parts easily. what do you reccomend for carbs? also for efi, i don't want to go too crazy with initial cost. but the tuning would be alot easier and consistant than carbs. what do you guys think? BTW, i use my car for autocross, daily driving, rallycross, and drag racing. I also want to be able to drive it long distances without any problems, and i want to beable to get 20mpg if possible or better. i hear stories of ppl getting over 20-25+mpg with tripple carbs when tuned properly. anyways, thanks! Quote Link to comment Share on other sites More sharing options...
Iceman Posted September 30, 2009 Share Posted September 30, 2009 You can probably get 20-25mpg pretty easily with any well-tuned setup. Your HP goal is probably going to be the most important factor. You can get a bit more power if you swap to an L28 engine. What are you trying to obtain that you don't have right now, just a higher power-band? More HP? Quote Link to comment Share on other sites More sharing options...
subtle_driver Posted September 30, 2009 Author Share Posted September 30, 2009 i personally want to stick with the l24 in this car. I like how it has a shorter stroke and revs a little better than the l28. if power was my only goal with this car i would swap in an rb26 with a massive turbo. or just a stock ka makes more power than the l28. my goal is more power with this current setup. the su carbs, i hear, do not have the throttle responce that the accelorator pumps on the webers provide. i also want to beable to change jets and tune the entire rpm range without calling around for custom made su needles. I am also just wanting to have fun and learn a new type of carberator. besides, i have always wanted a set of tripples since i first bought the car back when i was 17. the su carbs leave alot to be desired when i comes to tuning. i have a wideband and just wish i could change some jets or whatever to adjust afr's at whatever rpm range i want. Quote Link to comment Share on other sites More sharing options...
PanzerAce Posted September 30, 2009 Share Posted September 30, 2009 Given an equal starting point, I would say go with EFI, without a doubt. I love my triples to death, but when I rebuild the engine, the Mikunis are going to get cleaned up and put into storage. They can be hard to tune, VERY temperature sensitive (especially with more agressive cams. You don't aim for a idle RPM so much as an idle RPM *range*. Also, you aren't going to get a goot triple setup for 600 bucks unfortunatly. Last set of triple mikunis I saw for sale was ~1500. You're also going to be looking at spending around that much for a good ITB EFI setup (though you'd still have to get a fuel tank, new fuel lines, etc, etc, etc). Also, while you might like the shorter stroke of the L24, with modern con rod bolts and the additional power per cylinder, the L28 will be just as rev happy. Quote Link to comment Share on other sites More sharing options...
Lazeum Posted September 30, 2009 Share Posted September 30, 2009 I think the money question is not only related to initial cost... It might cost some money over time to get some triple carbs tuned correctly. There's more than just power I guess also with side draft carbs such as noise, feelings, etc. If you change to ITB, I would also change the distribution to have fully tuneable ignition table as well to take advantage of the ECU => $$$$ Quote Link to comment Share on other sites More sharing options...
DrSideways Posted September 30, 2009 Share Posted September 30, 2009 Have you tried moving the needles up in the piston just a bit? You can use a dial caliper to measure the first one and then loosen the second one and put the end of the first one to the bottom of the other piston to push the second needle up in its piston the same amount. Make sure the second needle is loose and will move easily. This is a trial and error deal so keep notes and see how it goes. Since you have your wide band deal you should be able to get the idle back in place and then see how it drives. Also check ignition for proper settings prior to making fuel system changes. Try this as is will be cheaper than anything else. Alan Quote Link to comment Share on other sites More sharing options...
jerryb Posted September 30, 2009 Share Posted September 30, 2009 I actualy found the Mikuni tripples easy to work on....much easier than the Weber brand. I bought jets at a local motorcycle shop for dirt cheap and got them running great. Just takes time and patience. But EFI is ultimately better. Quote Link to comment Share on other sites More sharing options...
smokeybear Posted September 30, 2009 Share Posted September 30, 2009 The ITB EFI is going to be your best bet in terms of reliability and power. ITB + MS + 83 Turbo Dizzy = Good power and economy. Quote Link to comment Share on other sites More sharing options...
e_racer1999 Posted September 30, 2009 Share Posted September 30, 2009 I agree, EFI will have a higher start up cost, especially because you will need all of the EFI-related paraphernalia to go with it; but ease of use and lower maintenance will be great factors later down the road. Plus it will be more efficient, better power potential, and still be as cool looking OT - How's the S13 doing? Missin ya over @ the 'Rev Quote Link to comment Share on other sites More sharing options...
subtle_driver Posted September 30, 2009 Author Share Posted September 30, 2009 Have you tried moving the needles up in the piston just a bit? You can use a dial caliper to measure the first one and then loosen the second one and put the end of the first one to the bottom of the other piston to push the second needle up in its piston the same amount. Make sure the second needle is loose and will move easily. This is a trial and error deal so keep notes and see how it goes. Since you have your wide band deal you should be able to get the idle back in place and then see how it drives. Also check ignition for proper settings prior to making fuel system changes. Try this as is will be cheaper than anything else. Alan I have done that aleady, and it runs too rich down low to make up for the correct mixture up top. if i run it like this it will fill the crankcase with gas. The cheapest thing for me to do is order some re-profiled needles. but i called ztheropy and they didn;'t have anything for me. Quote Link to comment Share on other sites More sharing options...
subtle_driver Posted September 30, 2009 Author Share Posted September 30, 2009 The ITB EFI is going to be your best bet in terms of reliability and power. ITB + MS + 83 Turbo Dizzy = Good power and economy. does anyone have a complete setup list for this to work? what is MS? Ya, i would have to convert to a different fuel setup, but that isn't too bad, cause i am going turbo sometime in the future anyways. Quote Link to comment Share on other sites More sharing options...
e_racer1999 Posted September 30, 2009 Share Posted September 30, 2009 MS = megasquirt Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 30, 2009 Share Posted September 30, 2009 I have done that aleady, and it runs too rich down low to make up for the correct mixture up top. if i run it like this it will fill the crankcase with gas. The cheapest thing for me to do is order some re-profiled needles. but i called ztheropy and they didn;'t have anything for me. This is typical of the SU setup. This is why the Hitachi Flat Tops, or the HIF 6 Style SU are preferred for performance applications. With a separate idle circuit, the idle and transition can be tailored for emissions, while the main needle is used for cruise and performance. It's why so many people savage the flat tops for the needles in the Junkyard, as well, the taper is much more agressive than SU's. But remember, "The Flat Tops are Instruments of the Devil":icon56: Quote Link to comment Share on other sites More sharing options...
subtle_driver Posted October 1, 2009 Author Share Posted October 1, 2009 MS = megasquirt thanks man! Quote Link to comment Share on other sites More sharing options...
subtle_driver Posted October 1, 2009 Author Share Posted October 1, 2009 This is typical of the SU setup. This is why the Hitachi Flat Tops, or the HIF 6 Style SU are preferred for performance applications. With a separate idle circuit, the idle and transition can be tailored for emissions, while the main needle is used for cruise and performance. It's why so many people savage the flat tops for the needles in the Junkyard, as well, the taper is much more agressive than SU's. But remember, "The Flat Tops are Instruments of the Devil":icon56: i have the origonal flat tops in my closet. so i can use those needles in the round tops? is there more info on this? anyways, i just bought a set of 40mm tripple webers. i need a heat shield and some velocity stacks and air filters. i can't wait to learn and tinker with them. thanks for the advice, I think i will do both, first try that flat top needle swap? that tony d was talking about. then install the webers, then swap to itb efi, then turbo with an l28. I have 2 l28 blocks at my house. i'm prolly gonna sell one of the blocks and the head to make room for rebuilding my jeep engine. so ya, thanks alot!!! now im gonna go do some research on these webers! Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 1, 2009 Share Posted October 1, 2009 Argh, let me make it not so 'subtle': The FLAT TOPS have a separate idle circuit in them, allowing their needles to have a more agressive off-idle power taper. When you put them in a Typical SU you will get the same thing you already have: right up top, too rich down low. Without the custom cut needles and LOTS of time to achieve proper mix at all stations on the needle, it's not going to change. Seriously, HIF6's are preferred in Europe on a lot of cars simply because you don't have to make the 'Rich down low, just right up top' compromise. You simply adjust the idle like a conventional carb, and use the SU like you normally do...save the needle/jet relationship is accomplished with a screw as well, no more reaching under the car to adjust it blind or by feel. Again I mock: "Flat tops are instruments of the Devil!" Quote Link to comment Share on other sites More sharing options...
frank280zx Posted October 1, 2009 Share Posted October 1, 2009 [qoute]BTW, i use my car for autocross, daily driving, rallycross, and drag racing. I also want to be able to drive it long distances without any problems, and i want to beable to get 20mpg if possible or better. i hear stories of ppl getting over 20-25+mpg with tripple carbs when tuned properly.[/qoute] First of EFI would be your best bet!!.. second does nobody think the qouted is kind of akward? Rallycross, autocross, drag racing.. and 20 mpg hahah!! eeehm make up your mind Quote Link to comment Share on other sites More sharing options...
jacob80 Posted October 2, 2009 Share Posted October 2, 2009 I would say go with triple webers or mikunis Quote Link to comment Share on other sites More sharing options...
subtle_driver Posted October 2, 2009 Author Share Posted October 2, 2009 [qoute]BTW, i use my car for autocross, daily driving, rallycross, and drag racing. I also want to be able to drive it long distances without any problems, and i want to beable to get 20mpg if possible or better. i hear stories of ppl getting over 20-25+mpg with tripple carbs when tuned properly.[/qoute] First of EFI would be your best bet!!.. second does nobody think the qouted is kind of akward? Rallycross, autocross, drag racing.. and 20 mpg hahah!! eeehm make up your mind well to set the record strait, my 240z gets 23mpg average and i race it almost every weekend. my 240sx makes 350hp and gets 27mpg highway. my friend's 240sx i helped build gets 25mpg highway and makes 720hp at the wheels. ya, i want the best of both worlds! and proper tuning will get both! thanks for everyone's input! i appriciate it Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 2, 2009 Share Posted October 2, 2009 If you look at the lists of vehicles you gave...which ones have Webers/Mikuinis, and which ones have EFI...and which ones give you the best performance and economy? That kind of answers the question well... Quote Link to comment Share on other sites More sharing options...
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