AGRO_RB Posted February 8, 2011 Share Posted February 8, 2011 Hey all, Will be getting stuck into my first L-series build soon as a replacement for the dying L20E in my HR30 and I have a few (well, lots of) questions regarding different aspects of the motor, seeing as i've never really worked on an L series before (too used to RB's ) First of all, carburation. The motor i'm buying is out of a friends 260Z which now has an L28E fitted, the L26 has the original SU carbs. I'd like to stick with carburettors instead of going to EFI for a number of reasons i wont go into. Ideally i'm aiming for 180-200hp from the motor (any more is a bonus), will the SU's be capable of this or am i better off switching to triple Webers or similar? If so, which twin choke carbs are ideally suited to these engines? Secondly, will the head have to be touched to get the power figures im looking at? I'd like to get a new cam ground to suit the carbs, but im not really willing to spend thousands on a head if the motor will only give me at most 200hp, I may as well go back to what I know and swap an RB into the car. Next, exhaust, what's a good header for these motors that's comercially available and what size exhaust should I go with? I have a free'd up factory exhaust at the moment (cat removed, reso's in place of silencers, straight thru muffler) which is about 2'', but still seems to be restrictive on my 20. Should I do anything internally to the motor while I have it apart? I'll be giving the bottom end a freshen up with rings, bearings, new pistons if required, new pumps etc after an acid dip and wash. I dont want to go too nuts with this engine as I want reliability and the car's my daily driver. What other supporting mods would you guys recommend, e.g. ignition, cooling, etc, and what advice can you give? Also, please dont try steer me down the L28 path as a few people have tried to do with me now already 28s seem to be a bit of a pain in the ass to find in NZ and I know the condition of the 26 i'm buying, it's also being sold to me at a great price... Thanks in advance Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted February 8, 2011 Share Posted February 8, 2011 SU's are capable without batting an eye, 200hp isn't much of a stretch besides. "motor will only give me at most 200hp" 8| The head is everything! I would start there and put bottom end mods at the bottom of the list. "what size exhaust should I go with?" Seriously, 200hp, I bet the stock will suffice. Quote Link to comment Share on other sites More sharing options...
AGRO_RB Posted February 12, 2011 Author Share Posted February 12, 2011 So I presume it's not actually that hard to get power out of one then? Excuse my ignorance guys If any of you could recommend a good base build that will easily get me over the 200hp mark on carbs (Factory or otherwise) that would be much appreciated, as i've mentioned already, L-motor tuning is all new to me compared to RB's, which pretty much fit together like lego and are ridiculously easy to get good power out of. Thanks in advance Quote Link to comment Share on other sites More sharing options...
CamH Posted February 12, 2011 Share Posted February 12, 2011 What SUs do you have? Flat tops or round tops? You're going to need a lot of head work and a good cam to get to 200hp. That's a lot more than stock on an L26. If you can, you should at least start with an L28. Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted February 13, 2011 Share Posted February 13, 2011 Read, ask why a lot, hopefully understand a little: My L24 Build My engine is 2.7L and Im shooting for 200ft/lbs at the wheels. Have a read through it and see what you come away with. Quote Link to comment Share on other sites More sharing options...
Tony D Posted February 13, 2011 Share Posted February 13, 2011 Scott Burkhardt's 240Z ran at MSA's dyno event last year at 192RWHP. That was an 040 L28, running a worked head, Isky Cam, and basically a stock flat-top bottom end. Oh, and SU's. That's rear wheel, so that is right in your realm of stated desires if you were talking 'crankshaft' horsepower. It's a daily driver, not ill mannered at all. Very tractable. Frankly I'd call it 'sedate' compared to what I'd tolerate for my daily driver. But then again, I'm a bit off... But some of this commentary??? "Stock Exhaust"? Dream on. Extractors and a 3" do a STOCK engine good, on one that's hotted-up, it's mandatory. Unless you want to get intimate with a die grinder and that stock 40+ year old cast steel behemoth you got underneath the induction system now! The head is where the power will be found. Gas Flow it, cam it correctly, and your HP Goals are within reach as stated with an untouched bottom end. And yes, on an L26. Easy Peasy Lemon Squeasy, all it takes is dinero! Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted February 13, 2011 Share Posted February 13, 2011 I'd say headers are definitely underestimated, but people can get a little crazy with how big they think they need. There are exhaust diameter calculators for this and the numbers seem to always come out surprisingly low. There can also be such a thing as too big. Quote Link to comment Share on other sites More sharing options...
Tony D Posted February 13, 2011 Share Posted February 13, 2011 "There can also be such a thing as too big." Not from what I've seen. At least on the exhaust side. Extractors, maybe, exhaust pipe? Bigger=better. This is covered extensively elsewhere, but a 3" exhaust on a 2.4 is not 'too big'...in fact, it's just about right. Going slightly smaller won't hurt all that much if packaging is an issue...but if you got the space, may as well do it once. Quote Link to comment Share on other sites More sharing options...
AGRO_RB Posted February 14, 2011 Author Share Posted February 14, 2011 Interesting stuff. As i've mentioned, L28's, as much as i'd love one, aren't all that common here in NZ and the people that do have them aren't willing to part with them, and when they do, they want silly money, i'm actually considering importing one from the US Had a look at the motor today, SU's are flat tops, as i've said before i'll happily make the switch to triples and im open to anything, but if im having to spend thousands on head-work to make 200rwhp then I may as well make the switch to an FJ20, which was the original plan, a stock RB20DET or build my ideal NA, an RB30DE, which was my second option, and I already have the parts... The only thing holding me back when it comes to an RB swap is killing the cars originality, at least an L6 or an FJ is in that particular models list of factory motors... Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted February 14, 2011 Share Posted February 14, 2011 Seems to me that you already have what you need from an L28. Crank and Rods are the same as the L28 in the L26. The big difference in is the Bore diameter. You could get very close to 2.8L with that block setup. Your in the same situation. Might as well use what you have to build what you want. The is no sense in wasting extra money on things you already have that will fit your goals. The L6 and the RB have two different characteristics as Im sure your aware. Figure out which one you want to go with. I have 2 cars and 1 of each. I love both of them for different reasons. Most of the head costs I have been quoted for seem to be for repairs. The street porting is actually very affordable. Finding out your guides, seats, surfaces, etc are all in need of repair is what seems to cost money. Though if your going with the bigger valves while your replacing the seats you might as well put big enough seats in to accommodate the larger valve. The key is showing up with the head you want that has the stuff you want and being in reasonably good shape so all that has to be done is a good chamber port workover. Quote Link to comment Share on other sites More sharing options...
AGRO_RB Posted February 15, 2011 Author Share Posted February 15, 2011 It's a hard call really, an L6 will drop straight in with minimal fuss, an RB requires an R31 subframe which in turn means a conversion from drag-link to rack and pinion steering, hours of wiring, a new gearbox, custom driveshaft, and trying to find a long nose R200 LSD to have any hope of putting power to the ground. The ease of maintenance, familiarity and the fact I know an RB will make good power for next to no effort/money spent are all drawcards, but the L series is something rarely seen here, RB's are a dime a dozen, people dont dont look twice when they hear a 20DET, 25DET or even a 26 on boost, yet everyone seems to sit up and take notice when my sad little L20E picks up, its a whole different sound, plus the looks on peoples faces when they see an L series motor for the first time in the car, it certainly gives it some personality, with an RB swap, to me it'll just be another generic Skyline, i've been around and owned more than a few now to say I want something a little different. I'll definitely look into getting the head looked at, and will have a go at rebuilding the bottom end myself, the last time I put a motor together was college nearly 5 years ago so it'll be an interesting project. On the carburation side of things, are triples worth it? If 200hp is as easily achieveable as people are saying on the standard carbs then just how much can I get out of my motor with the mods most of you have thrown out there? Sorry for the million questions guys, would just rather do things once and do them right. Quote Link to comment Share on other sites More sharing options...
NZeder Posted February 15, 2011 Share Posted February 15, 2011 L28 can be found in NZ I have owned/purchased/sold a number - all out now sold the last one 12 months ago. There was is one on trademe right now if you look for $1 with a turbo tappet cover (you on sell that to get some of the purchase cost of the engine back) Get an L28 the extra 200cc will help with your power goals. One thing you did not state is your budget. Good HP = good work and good work will cost $$ if you don't/can't do it your self. You will want to balance the rotating mass and starting with 30+ year old rods not ideal. For the cost of prep'n rods just purchase some new items - there are number of suppliers that do L24 and L28 sizing. You ideally also what nice light slugs (aka pistons) the list goes on. But first if you have the stock 260z SU bin them they will be flat tops - get some 240z items if you can find some (now they are hard to get here in NZ these days). Most of this stuff has been covered over and over again on this site and others - read read read and then read some more - get a good engine builder involved if you can't do it your self and have a budget before you start and try and stick to it. You can spend anything from $1000 - $8000 (including purchasing triples, new headers, clutch/flywheel etc for this high end price) Quote Link to comment Share on other sites More sharing options...
AGRO_RB Posted February 16, 2011 Author Share Posted February 16, 2011 If I can get my ute sold, i'll have about $4500-5k (NZD) to play with... if that helps. Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted February 16, 2011 Share Posted February 16, 2011 (edited) L28 can be found in NZ I have owned/purchased/sold a number - all out now sold the last one 12 months ago. There was is one on trademe right now if you look for $1 with a turbo tappet cover (you on sell that to get some of the purchase cost of the engine back) Get an L28 the extra 200cc will help with your power goals. One thing you did not state is your budget. Good HP = good work and good work will cost $$ if you don't/can't do it your self. You will want to balance the rotating mass and starting with 30+ year old rods not ideal. For the cost of prep'n rods just purchase some new items - there are number of suppliers that do L24 and L28 sizing. You ideally also what nice light slugs (aka pistons) the list goes on. But first if you have the stock 260z SU bin them they will be flat tops - get some 240z items if you can find some (now they are hard to get here in NZ these days). Most of this stuff has been covered over and over again on this site and others - read read read and then read some more - get a good engine builder involved if you can't do it your self and have a budget before you start and try and stick to it. You can spend anything from $1000 - $8000 (including purchasing triples, new headers, clutch/flywheel etc for this high end price) seriously 200cc's, you think its the whopping 200 cubic centimeters of displacement that will help!? Its 200cc's! The benefit here is not in the displacement of 200cc's, but rather BORE diameter and valve shrouding/size. Im not denying 200cc will make a wee bit more power, Im just stating that should not be the significant reason that should guide your decision process. 200cc's is bonus points if its how you deal with the cylinder head/combustion chamber flow characteristics. And then onto the flat top comment... I refer you to your own quote "Most of this stuff has been covered over and over again on this site and others - read read read and then read some more" If youd followed this advice you would not have made such a comment. You might have actually put your hands on a set of flat tops to discover there hidden attributes that no round top will get you without significant modification. This has actually been discussed in more recent topics. Perpetuating the "Boat Anchor" myth once again. I would encourage talking with a real engine builder that is intimate with the L-series engines(one thats been building them for years with good results). It would greatly benefit all. I have had no problems speaking with any of the engine builders over the phone here in the states. All the big names seem more than willing to divulge information one would think was secret. Edited February 16, 2011 by rayaapp2 Quote Link to comment Share on other sites More sharing options...
NZeder Posted February 16, 2011 Share Posted February 16, 2011 (edited) yes I seriously I think 200cc will make that much of a difference for the same reason you stated the bore size I did not go into that as I thought he could look that up him self. We all know the performance is in the head/flow and to get the valve area required you want a larger bore. Nissan knew that too. So why have a dig a me. Re the flat-top I still have mine I was trying to help him out from a local point of view - not too many good SU's guys down here and if you need to get support for them the 240z better option. I would personally go triples, more displacement, lighter rods/pistons and spend $$ with a good L6 head guy for HP chasing. Edited February 16, 2011 by NZeder Quote Link to comment Share on other sites More sharing options...
AGRO_RB Posted February 16, 2011 Author Share Posted February 16, 2011 I've dealt with SU's and Strombergs a bit over the years, mostly the HS4 and HIF44 carbs on Minis though although im sure they won't be too dissimilar, their construction certainly isn't anything new to me. A friend and myself sat down the other night and did a little research into the L6 lineup, and thought that being the closest to square-bore out of the lot, the 26 would be a good way to go for a good balance of power and torque, not to mention I like a motor that's quite peaky, as in, makes most of its power in the top end. NZeder, how much have you seen triples sell for over here? Last I priced up a Weber DCOE40 for my old Mini 1275 motor (wouldve been early 2008) they were around the $400 per carb mark, then another $200 (each) for the manifold but I suppose this would vary between motors and also now that the exchange rate and currency values have changed I suspect the price has increased quite a bit. Also is my $5k budget enough to cover mods? Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted February 16, 2011 Share Posted February 16, 2011 (edited) So 200cc's doesn't help much but by the same token a larger bore does? And the difference in this context is... Sure you can't compare apples and oranges, a displacement up isn't the only thing that's going to make a difference. My old engine was the same displacement as my new one but was probably about a third the power output for instance. I'm quite sure he was generalizing. Although a square cylinder is reputedly the most efficient type, I wouldn't be hasty and say that an engine best fitting this design to necessarily be the most balanced by any means. Since the only difference is the slightly larger bore you could essentially stroke it 3mm to 2.9L and keep the same aspect but I don't know if anyone would go through the trouble of adding 100cc's for the sake of squaring the cylinders (or even stroking it to a 3.0 and having the cylinders completely square for that matter). Consider sleeving the cylinders to decrease the bore for the sake of squaring them off, sounds pretty silly right? Now if you wanted to make an engine with cylinders 100x55, then we'd have a problem Edited February 16, 2011 by getoffmyinternet Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted February 16, 2011 Share Posted February 16, 2011 (edited) So 200cc's doesn't help much but by the same token a larger bore does? And the difference in this context is... Sure you can't compare apples and oranges, a displacement up isn't the only thing that's going to make a difference. My old engine was the same displacement as my new one but was probably about a third the power output for instance. I'm quite sure he was generalizing. Although a square cylinder is reputedly the most efficient type, I wouldn't be hasty and say that an engine best fitting this design to necessarily be the most balanced by any means. Since the only difference is the slightly larger bore you could essentially stroke it 3mm to 2.9L and keep the same aspect but I don't know if anyone would go through the trouble of adding 100cc's for the sake of squaring the cylinders (or even stroking it to a 3.0 and having the cylinders completely square for that matter). Consider sleeving the cylinders to decrease the bore for the sake of squaring them off, sounds pretty silly right? Now if you wanted to make an engine with cylinders 100x55, then we'd have a problem The difference is the thought process behind the reasoning. Its not the displacement that makes the difference. And if you realize that your much better off in the engine build process than thinking its the 200cc that makes the gain. NZeder, my apologies if I come off as a bit rough. There was no hint though of any other thought process behind your statement. It seems its very common to take that exact line of thought and run down the field with it without ever touching on the real reasoning why the 200cc helps. One could certainly start with an L20A and give it an 86mm bore and come out with similar results without ever being anything more than a 2.4L(Though there are some getting those power goals from the 2L itself). Its all about "Volumetric Efficiency". I hadnt realized you knew any of this by your comment and it was not really helpful to the thread starter. I am guilty of not explaining myself at times as well. Before any over-bore is explored check to be sure your block is good for it with your build goals in mind. My personal finds is that my P30 block is good up to about 86mm for my power goals as an example so Im leaving room with an 85.5mm bore. Edited February 16, 2011 by rayaapp2 Quote Link to comment Share on other sites More sharing options...
NZeder Posted February 16, 2011 Share Posted February 16, 2011 (edited) The difference is the thought process behind the reasoning. Its not the displacement that makes the difference. And if you realize that your much better off in the engine build process than thinking its the 200cc that makes the gain. NZeder, my apologies if I come off as a bit rough. There was no hint though of any other thought process behind your statement. It seems its very common to take that exact line of thought and run down the field with it without ever touching on the real reasoning why the 200cc helps. One could certainly start with an L20A and give it an 86mm bore and come out with similar results without ever being anything more than a 2.4L(Though there are some getting those power goals from the 2L itself). Its all about "Volumetric Efficiency". I hadnt realized you knew any of this by your comment and it was not really helpful to the thread starter. I am guilty of not explaining myself at times as well. Before any over-bore is explored check to be sure your block is good for it with your build goals in mind. My personal finds is that my P30 block is good up to about 86mm for my power goals as an example so Im leaving room with an 85.5mm bore. True I did not explain my thought process for the extra 200cc. I have seen a few L24/26 (P30)taken out to the 86mm bore and that setup does work well. Again depends on how much valve area you are going for 86mm might not be enough either With his budget in mind of around $5K NZD this will be the limiting factor in this build. My last L28 build was a 90mm bore with L28 stock aka 3015cc using some cast pistons I did a deal on from Japan so the pistons were RRP $800USD (not what I paid), they were top quality and weight only 30g more than a mates JE forged items (his are 87.5mm). These were designed for the L28 crank and L24 rods so that was my setup. By the time I prep'ed the L20A (pre 79 L20a = same rods as the L24) rods (had them modified to take RB30 little end bush as these are nice readily available) that was $650 NZD and I could have just purchase some new L24 spec H-Beams from MaxspeedingRods for that coin - never mind live and learn. My L28 crank was knife edges, balanced blah blah another $1000, new bearings, sonic testing, overbore and having a good shop setup the bottom end for me another $3K So basically that is over his budget already before we started on the head or the accessories to go with it - headers, triples (well throttle bodies is what I had for this engine now going on to my new setup) this engine goal was between 230HP-250HP with the EFI setup. I moved this engine on before I completed it and the new owner installed his 40mm triples (as that is all he has) and its first dyno outing for turning it put down 215HP at the wheels. There is still a lot of potential in that engine and more development to come if budget permit (he will be breaking his gearbox next is my guess) Again your budget will limit your HP goals if you have nothing to start with - ie need to purchase a L28, carbs, headers, fuel system upgrades etc. This is going into a R30 so that will be setup for EFI so you will need to change the fuel pump to a lower pressure item so that is extra $. If however $5K will build a good strong reliable L26/L28 that would be a good fast road engine which is your goal. My first 240z race car was an L28 stock bottom end, a cam that back in the 90's was known as the Taupo cam as it worked well around the Taupo track (reads just a good mid/mild cam with good pull out of the corners) some triple 40mm Mikuni's or Webers (I had both on the car at different times) and some headers from Custom Chambers here in Auckland going to a 2.5" single system. So this is the closet car that I have owned that fits the bill (others were 3.2 or stock L24/26 setups or even L28 EFI in 280zx) for your goal. So were am I going with this......this 240z was an auto too, it was very good on the road, fast and fun to drive. On the track well that was a different story, the auto was the big handicap. I see you would like around 200RWHP well that auto 240z I had back in the late 90's made a grand total of 105hp at the wheels that was all vs most over zed on the same dyno shoot out that night that made 160-180HP with sim mods (usually 45mm carbs) but then it was 6 seasons old, very fumy and blew up 10months later at the drags. The point I have owned motorbikes that almost made as much power but this auto zed was a lot of fun on the road and was fast enough to break the law and get you into trouble. You will also need to get the engine update/install certified as it will be larger than the original so will fall into requires an engineering cert for it to be road legal here in NZ so that is going to cost you anything between $400-600 at a guess. Also a cert is required if you increase the engine output by 20% and you will have to have a drive shaft hoop installed. The list goes on. So if you have to do that you might as well just purchase one of the many FJ20T on trademe for $1500, get the cert work done for that conversion - should not be to hard as you can prove Nissan installed those in that model from the factory, so a cert might not even be required (unlike fitting a L26/28 which was never factor fitted that I am aware of) this has more HP potential going forward. So in my opinion (which you can ignore if you wish ) to your statement Also is my $5k budget enough to cover mods? is no it is not enough for a L6 build to make 200HP at the wheels here in NZ with current cost of parts/labour. NZeder, how much have you seen triples sell for over here?$1200-1500 does not seem to mater if 40mm or 44/45mm. New items will set you back $2500-3000is If you want something different to the normal RB power R31/R30 that are around then stick with the L6. If you are after HP well you will want $$ for L6 in NA form. Hell whatever you do L6, RB, FJ it will all cost money and you can't take it with you right - so spend away Edited February 16, 2011 by NZeder Quote Link to comment Share on other sites More sharing options...
AGRO_RB Posted February 19, 2011 Author Share Posted February 19, 2011 So basically I can rule out an L26 being an ideal choice for the power figures im after, on my budget? There's no SIMPLE ''throw it together and make it work for SFA money'' way of doing it? The FJ was always a tempting engine, requiring only a DR30 dash, engine loom and ECU, its trying to find a gearbox and an uncut loom that's the hard part, and some traders don't make it clear that the motor they're selling is an ET or just an E. I've got RB's and parts coming out of my ears and to be honest i'm a little over them, Was actually tempted to buy a complete 26DETT for $4500 and a 25DET box for $1500 and be done with it, but being a near base spec model my brakes and suspension wont cope and with me not willing to go any bigger than a 15'' wheel (nostalgia thing ) a GT-R motor's sorta out of the question as well... decisions... Quote Link to comment Share on other sites More sharing options...
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