e9 Posted March 17, 2009 Share Posted March 17, 2009 I'm intending to use the Zed as a daily and being a uni student I'm more or less a tightwad so I'm looking for something that will run economically and deliver around the 160hp that the L26 did when it was new or perhaps a way to improve economy in the current engine (it's using 240 carbs right now if that helps any). I do about 50/50 highway driving so I'm trying to keep that in mind but right now I'm thinking a CA18DE(T) or RB20. Any thoughts or suggestions? L28 conversions seem popular, what's the take on that? Also would I need to change the box up or anything in the exhaust apart from extractors (I'm a newbie but I'm learning, slowly)? Quote Link to comment Share on other sites More sharing options...
Administrators gav240z Posted March 17, 2009 Administrators Share Posted March 17, 2009 Fuel economy of the old L-series isn't too bad provided you have electronic ignition and run well tuned SU carbs. I prefer keeping the original L-series engine in my Zeds, but engine swaps are common. If fuel economy isn't a problem then L-series engines can be made to perform well. I personally wouldn't put a CA18DET in my Zed, but I'm sure it can be done easily. Quote Link to comment Share on other sites More sharing options...
stevo_gj Posted March 17, 2009 Share Posted March 17, 2009 I've been down this road. Unless you can do the engine conversion yourself, and probably even then, the amount of driving you would have to do to make up for the initial outlay of cash will take you a bloody long time to reach. I did the math, if I went from 14L/100km which I have running rich on my shit 260z carbs, down to 9L/100km of a fairly mild RB engine or SR20, then I'd be looking at saving about $1K (probably less) per year on petrol IF I drove it 5 days a week to uni and work. I've also been told to budget about 10K for a conversion done right, if I was getting reasonably cheap labor. That would mean it would take me a decade to earn that 10K back. Even if you drive a lot more than me, is 5 years a short enough time to see a return on your investment? Don't get me wrong I really want to get an RB25 but I need to be realistic about my reasons, and to save money from petrol isn't a very good one. I want a reliable modern powerplant (with a turbo) capable of surprising most people when they see the classic lines of my car. Fuel efficiency will be better but that can't be quoted as a reason for getting it really. L28 EFI would probably be a cheaper way as I'm pretty certain fuel injected L28s are better on petrol than twin carby L26s. Just remember carbys, while sounding great and very easy to work with, are not capable of being as efficient as EFI. An L28 would probably suit your power needs quite easily though, and the advantage is that its very very similar to the L26 and therefore does not need to be engineered. If you did the conversion to SR or CA, I'm not sure if you would need to change the box for any other reason than that your current one will not bolt up to the new engine. However if you put a turbo onto it then its a different story, and you'll definitely need a stronger box. N/A should be fine for 160 hp anyway. There is a lot of info on these conversions on this forum, have a look around the engine section. I kind of felt the need to spill my guts on this topic, as its very close to my heart. If I have made any mistakes please fill me in on it guys! -Steve Quote Link to comment Share on other sites More sharing options...
ozy Posted March 17, 2009 Share Posted March 17, 2009 my L28 is recently reconditioned and as i only drive it at weekends, i dont keep track off fuel economy. but my initial feeling is that its not too unlike my old sr20det (turbo s15). so m happy BUT if the engine was to blow up, my excuse for an RB engine would have finally come about, that would be nice, but i fear that it wouldnt make the same noise as my lovely carbie L28. ah no, carbie engine all the way, as above, fuel economy and expense of conversion....feck that Quote Link to comment Share on other sites More sharing options...
RBZ 260 Posted March 17, 2009 Share Posted March 17, 2009 if u drivelike a grany than keep the L. L28 will guzzle lot more than stevos figures for his l26. im even suprised of the L26. than again who drives a Z like a granny? if do u dont deserv to have one (I better start running for cover) RB20DET is not bad on fuel and has lot more than 160hp. prob closer to double that with few mods = very exciting and fast car. being young prob not a good formula. In my case i wanted a modern engine with parts availability and huge aftermarket support. than something that when not pushed gives good economy.( lets face it to make the power u got to put the energy into it so more power more fuel) but where things even up or become good is when u dont mash the right foot down but just cruising along. i get roughly 10L/100km on average out my rb20det. and gets a good squirtfull daily its been in the car for 2 years and no issues with motor what so ever besides the every 4000km services to keep it happy. SR20det be better option little bit lighter than rb20 and slightly better fuel economy. power is about the same but sr20 has lot better tourque curve than RB20. rb20 needs to be reved unilke sr20. to help you out. well if u doing it purely for fuel economy than its a false economy like Stevo found. if u doing it for extra power and reliabilty and hassle free (no constant tunning required) and to better fuel economy it may be worth the effort. Quote Link to comment Share on other sites More sharing options...
e9 Posted March 18, 2009 Author Share Posted March 18, 2009 I wouldn't mind the increase power so it would be more for economy but also restoring original performance, but just driving it today my right foot kept getting heavy so perhaps not. Having the mech doing the roadworthy replacing the rear wheel bearings put a dent in the budget as well. Basically I guess I'll stick with the carbies for now, play around, learn a bit and then move on. Couple more questions though: Does http://www.classiccarhub.co.uk/articles/perfomance/guide_to_setting_up_tuning_su_carburettors.html contain what I need to know for carb tuning? Should I tune plugs then carbs, carbs then plugs or carbs/plugs/carbs/plugs/carbs/plugs etc? Should it rev to 4.5K when it's cold with the choke on? How long exactly should I warm it for (we're talking QLD weather, usually 20C but as low as 13C if when I get up early in the winter)? Was $550 too much for replacing 4 wheel bearings (parts and labour, I have the feeling I was bent over a bit)? Quote Link to comment Share on other sites More sharing options...
stevo_gj Posted March 18, 2009 Share Posted March 18, 2009 I wouldn't mind the increase power so it would be more for economy but also restoring original performance, but just driving it today my right foot kept getting heavy so perhaps not. Having the mech doing the roadworthy replacing the rear wheel bearings put a dent in the budget as well. Basically I guess I'll stick with the carbies for now, play around, learn a bit and then move on. Couple more questions though: Does http://www.classiccarhub.co.uk/articles/perfomance/guide_to_setting_up_tuning_su_carburettors.html contain what I need to know for carb tuning? Should I tune plugs then carbs, carbs then plugs or carbs/plugs/carbs/plugs/carbs/plugs etc? Should it rev to 4.5K when it's cold with the choke on? How long exactly should I warm it for (we're talking QLD weather, usually 20C but as low as 13C if when I get up early in the winter)? Was $550 too much for replacing 4 wheel bearings (parts and labour, I have the feeling I was bent over a bit)? Have never tuned carbs or done the plugs so thats better left answered by someone else. It's revving to 4.5 with JUST the choke in, or with your foot on the pedal as well? When its idling with the choke in mine sits around 1100-1400 RPM from memory. If yours is idling that high I'd suggest there is something wrong. I would never rev my engine that high when its cold. I consider it warm when it comfortably idles with the choke off. This is usually when the temp needle has reached the left limit of the temp gauge. (starting like 1-2cm to the left of this limit when cold) It takes me between 2-5 minutes to reach this. If you are talking about letting it sit before you drive it, I do not bother and just drive it carefully with the choke on until this temperature is reached. I have no idea about the price of wheel bearings. If you want to restore performance, refresh the engine. Check out the 'L26 refresh results' thread. Here's an easy/cheap one: have you checked your air filter? It sounds a bit expensive, but I'm not an expert. HTH Quote Link to comment Share on other sites More sharing options...
e9 Posted March 18, 2009 Author Share Posted March 18, 2009 Have never tuned carbs or done the plugs so thats better left answered by someone else. It's revving to 4.5 with JUST the choke in, or with your foot on the pedal as well? When its idling with the choke in mine sits around 1100-1400 RPM from memory. If yours is idling that high I'd suggest there is something wrong. I would never rev my engine that high when its cold. I consider it warm when it comfortably idles with the choke off. This is usually when the temp needle has reached the left limit of the temp gauge. (starting like 1-2cm to the left of this limit when cold) It takes me between 2-5 minutes to reach this. If you are talking about letting it sit before you drive it, I do not bother and just drive it carefully with the choke on until this temperature is reached. I have no idea about the price of wheel bearings. If you want to restore performance, refresh the engine. Check out the 'L26 refresh results' thread. Here's an easy/cheap one: have you checked your air filter? It sounds a bit expensive, but I'm not an expert. HTH That's without throttle, I put the choke in and it just kept climbing so I freaked out and let it off. But now I'm thinking I'm a retard and have been driving with the choke in all this time (that's what happens when you have a noob without a choke light). I have to climb a hill before I go anywhere, does this change anything or just use low revs up? I'll check the air filter today. Quote Link to comment Share on other sites More sharing options...
ozy Posted March 18, 2009 Share Posted March 18, 2009 maybe your cables are crossed? Quote Link to comment Share on other sites More sharing options...
e9 Posted March 18, 2009 Author Share Posted March 18, 2009 Please elaborate. Quote Link to comment Share on other sites More sharing options...
ozy Posted March 18, 2009 Share Posted March 18, 2009 oh i dont know, just popped into my head, maybe the choke cable is snagging of the throttle cable to such an extent that it revs the engine exactly to 4500 revs. i doubt it, just throwing out the whole, could be something simple answer. is it still revving too high? only does it when the choke is on? you live in queensland? do you need the choke? my Zed is in ireland, 20 is a hot day, i dont really need the choke over 5 degrees celsius, 13C is still warm here, mad Quote Link to comment Share on other sites More sharing options...
Administrators gav240z Posted March 18, 2009 Administrators Share Posted March 18, 2009 Yeah choke fully out and mine will climb to about 3500rpm, the idea behind the choke is for initial start up pull her right out, then as temp climbs just slowly push it in, till its warm. A warm Z should be able to idle at about 700-800rpm without choke. Biggest problem with the choke is often the centre console snaps and the cable comes loose as the screw that holds it in place doesn't work properly then. Quote Link to comment Share on other sites More sharing options...
ozy Posted March 18, 2009 Share Posted March 18, 2009 fully out should climb to 3500? mine deffo doesnt go anywhere near that. i normally assist the revs up to 3000 myself till im happy shes warm enough. Quote Link to comment Share on other sites More sharing options...
Glen Posted March 19, 2009 Share Posted March 19, 2009 I don't believe the RB would cost 10G, although i guess that depends on the model of RB motor you are looking at. Presently you can pickup a series 2 RB30 for next to nothing. By the time you factor in loom, and mounts from CM and a gear box you could still do a NA Rb30 for $1500 (not including Certificate). But if you want to go fast with a RB25 and not go a turbo then you could be looking at $1500 alone for a motor. Easiest cheapest for me is RB30ET. I should have my project done for around $3500. You could throw 3.5g at a L series and you wont see 175rwkw's. Downside is a L series with Triples not only looks the goods but sounds awesome as-well and there is something special about waiting for your motor to warm-up to. Quote Link to comment Share on other sites More sharing options...
stevo_gj Posted March 19, 2009 Share Posted March 19, 2009 I've also been told to budget about 10K for a conversion done right, if I was getting reasonably cheap labor. I don't believe the RB would cost 10G, although i guess that depends on the model of RB motor you are looking at. Yeah I was talking an RB25DET installed by a professional here in Brisbane who has built a few race Zs with RB30s. If you are doing the work yourself then there's no labor costs. Quote Link to comment Share on other sites More sharing options...
Glen Posted March 19, 2009 Share Posted March 19, 2009 Honestly you dont need to be a mechanic to do what im doing as just about everything im putting on is factory for that motor. Having the VLt ECU is no doubt is what is keeping this project costs right down. Even if you plan do a turbo rb30 in hte next 2 years i suggest you grab a Vlt ECU now while there still seems to be a few around. Going Microtech and then adding a tune and wiring can alone cost you 2k if everything ran smooth, and thats a cheapie standalone ECU. The VLt ECU you pick for $150 and is good to run 10-12 pound. Diference between a RB30E and RB30et is the Pistons and Cam, thats it I have another S2 motor in my shed that im going to build to factory turbo specs just incase. Quote Link to comment Share on other sites More sharing options...
dorifticon Posted April 1, 2009 Share Posted April 1, 2009 If you are concerned about fuel economy on your L6 then I can highly recommend the L24E head swap from the MR30 skyline (aus-spec). I get around 10L per 100km around the city with "enthusiastic" driving and 8L per 100k on the highway (on 95 octane). I am using the e88 head from the skyline mr30, which has the "closed chamber" or peanut-shaped combustion chamber. I bolted the complete head - manifolds, injectors, cams, valves etc - onto the L6 bottom end. I also used the factory ecu and afm. I also bolted up the electronic ignition from the MR30 (swapped the complete unit over). Overall, there is not much change in the power, however response is far more linear and it revs a little faster. The cold start is fantastic, it just starts and runs and you drive it w/o having to worry about chokes etc. And fuel consumption is drastically reduced, I have saved hundreds of dollars by now. The efi system requires no balancing, tuning etc unlike the factory 260z twin carbies, which I found problematic to say the least. My conversion was also essentially free, as I bought the wrecked mr30 with the motor and gearbox for $300, sold the 5-spd stumpy for $250, and then the scrap metal for $50. I also sold my factory carby head an inlet which paid for the high-pressure fuel pump and gaskets. You may want to consider a fuel computer as well, however - my setup is running a bit lean at the moment. It hasn't caused any dramas but ideally you'd want to be able to control afrs to some extent. Quote Link to comment Share on other sites More sharing options...
nuclear_z Posted April 30, 2009 Share Posted April 30, 2009 Using a standard computer is the cheapest route initially, and is less likely to give u issue down the line. That being said, standard ecu's only give good economy when everything operates like standard. Similar inlet tracks and temps, injectors, the whole kit... Even changing an exhaust may effect economy. I drove from coffe back home today, well over 500kms and used 47 litres. That's on a over 200bhp turbo l28... It's got a great tune though and it was highway all the way Quote Link to comment Share on other sites More sharing options...
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