ovenfood Posted September 22, 2011 Share Posted September 22, 2011 Ok so I'll start with what I have, two LD28 cranks (V07) sets of twin SU manifolds flat top and round top 1 3/4 SU's two 2inch SU's off a jag (no other information was given) two F54 blocks (L28E blocks from 83 280zx's, still complete engines) two N24 blocks (L28E blocks from something... one complete one not) two L24 engines from 1974 240k's (still in the cars one still runs and the other is rusted/seized) a few N24 heads from L28E's 5speed 280zx boxes and R200's I want to build an L31 with twin SU's and extractors and put it in my 74 240k this particular 240k is one that has been in my family since new and I have always desired this car. So now that I own it I want to make it really special One of the main reasons I want to run this combination is that I want an average person to see this car and think thats a stock (or with minimal mods) car. My issue is that I am starting to think the SU's may be too hard to tune correctly as I have very limited knowledge about them. Im not looking for unreasonable high horsepower but with some thing in the range of 200hp to 300hp should do fine Does this sound like something that will be too hard to get right for a weekend street menace? Or should I just stick to an EFI setup Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted September 22, 2011 Share Posted September 22, 2011 Whatever you do, hang on to those front sump oil pans. Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted September 22, 2011 Share Posted September 22, 2011 The SUs may have been instituted for economy and less desired for racing because their design lacks throttle response, but overall they're quite free flowing and perfectly capable of that kind of power in good hands. Tuning them shouldn't be too difficult, but they aren't quite like carbs you may be used to, all the information is out there. I have an old school book solely devoted to SU overhaul and tuning lying around somewhere. It's not like they have a thousand moving parts or anything. On the other hand, EFI is nice... Sorry I wasn't any help. Quote Link to comment Share on other sites More sharing options...
Noddle Posted September 22, 2011 Share Posted September 22, 2011 Whatever you do, hang on to those front sump oil pans. why's that ? Quote Link to comment Share on other sites More sharing options...
ovenfood Posted September 22, 2011 Author Share Posted September 22, 2011 This won't be a full race engine as I don't plan to push the 240k the full 10 10ths I have faster less valuable cars for that part of the reason I wanted to go SU's is because kids my age don't think carbies can produce any real power for the same money and I wanted to see if I could step outside of what I know and use all the techniques of the cars era to get a decently powerful engine. Although it is tempting to make it efi. Quote Link to comment Share on other sites More sharing options...
ovenfood Posted September 22, 2011 Author Share Posted September 22, 2011 @noodle. because ill need one Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 22, 2011 Share Posted September 22, 2011 Check the 200HP N/A thread for examples of what you want. A properly matched cam to a gas-flowed head should easily meet your goals. Scott B. in our car club had 182HP to the rear wheels on a 1mm over L28 at below 6500 rpms with STRONG bottom end using the original SU's from his 240. Originally he thought Triples would be needed...he was really happy with the SU's ease of maintenance since he maintained them for years before making the jump to a performance engine. And those were not 2", they were the original 45mm SU's from the L24. Quote Link to comment Share on other sites More sharing options...
ctc Posted September 22, 2011 Share Posted September 22, 2011 You could go EFI with the SU carb bodies. It has been discussed here a few times. Quote Link to comment Share on other sites More sharing options...
ovenfood Posted September 22, 2011 Author Share Posted September 22, 2011 @ Tony D, do you think 2" is overkill? @ctc, I was talking to the machine shop at work and we drew up some ideas on that and it seams feasible the only thing is the injectors may need to be of a quite high flow capacity to keep up (not sure on the numbers as it was just spit balling) Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 22, 2011 Share Posted September 22, 2011 (edited) d/p . Edited September 22, 2011 by Tony D Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 22, 2011 Share Posted September 22, 2011 50#/Hr is about 100 HP each injector. Ford HO TBI used twin 550cc injectors to support V8's with 215HP ratings, so in the 200HP range twin injectors would be in a manageable size. GM Style injectors are larger flow and work in the TBI application as well. Port injection on the SU manifold has also been done using conventional small capacity injectors. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted September 22, 2011 Share Posted September 22, 2011 In many markets, the rear sump pans outnumber the front sump pans by a margin of around 300 to 1. I'm sure they are more common in australia, though. Quote Link to comment Share on other sites More sharing options...
Noddle Posted September 22, 2011 Share Posted September 22, 2011 In many markets, the rear sump pans outnumber the front sump pans by a margin of around 300 to 1. I'm sure they are more common in australia, though. Yes, very common, I have 3 spare engine (2xL28) and 2 running in my cars that have front sumps. but alas, no local 'L' turbo stuff. ( all imported from the US for me ) Quote Link to comment Share on other sites More sharing options...
BlueStag Posted September 22, 2011 Share Posted September 22, 2011 I was into Brit cars long before I owned a Z engine, which is in my Brit car expressly because the Z engine has SUs on it. Kind of stupid, when you think of it.......... A pair of 2" SUs can be matched without any issue to a 3.1L straight six. Now, the trick will be getting the right needles into them. You need to have the SUs evaluated by someone who really knows their ear from their elbow on SUs. For that I would call Z Therapy and ask them for a price to just evaluate the carbs. Hopefully you know that the throttle shaft has almost certainly worn the carb body, and that sleeves or some such will be required to make the blessed things breathe without sucking air in at the throttle shafts. Next you need to find a Brit car carb tuning dude. Likely he is about 110 years old. A dyno and about a dozen needles. Or two dozen. And possibly more than a few pairs of springs to push the piston down. If you can find a list of approved needles for various Brit cars, you might get lucky. Here's the trick: An Austin Healy 3.0 may have about the same size straight six, but that engine will have nothing like the potential of a properly built 3.1. Possibly only 2/3rds. Jag built some smaller straight sixes that you may not even be aware of, but they might have about the potential of your stroker. Those engines would likely have about the needle that you need. Fuel injecting the SU's? News to me. Gotta go look that up. This one is mine: Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted September 22, 2011 Share Posted September 22, 2011 (edited) Stag, Here's the thread, xnke and z-ya both have done it. I believe Z-ya was selling them at one point. http://forums.hybridz.org/index.php/topic/85654-su-fuel-injection-manifold-conversion/ Edited September 22, 2011 by BluDestiny Quote Link to comment Share on other sites More sharing options...
ctc Posted September 23, 2011 Share Posted September 23, 2011 (edited) Link to post on SU, TBI injection... Breezed over it, but has some good information. Tony D pointed out the GM way to go. I have read some other thread here discussing SU derived fuel injection systems, but did not book mark them. Link Edited September 23, 2011 by ctc Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted September 23, 2011 Share Posted September 23, 2011 Hey Tony, if the Scott you're talking about has a blue Z, he put down 198hp on a hot day with triples. I don't know if he's done more to that motor since it's had the SUs but that car sure does scoot! Quote Link to comment Share on other sites More sharing options...
ovenfood Posted September 23, 2011 Author Share Posted September 23, 2011 Tony D, 550cc does sound like it would be ok. I have a set of 550cc denso injectors for my RB20DET so I could always try them . Does the angle the injectors sit at play a big part in their effectiveness? HowlerMonkey, front sump L6 engines are all over the place hear I've even taken a few to the scrap metal yard... Noodle, did you need some turbo stuff? a mate of mine is trying to sell some stuff. Bluestag, nice car I do hope when it comes to it I can find an SU guy but I don't like my chances.. Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted September 23, 2011 Share Posted September 23, 2011 Yes, very common, I have 3 spare engine (2xL28) and 2 running in my cars that have front sumps. but alas, no local 'L' turbo stuff. ( all imported from the US for me ) So the grass IS always greener on the other side! We're sending you L6s and you're sending us RBs Quote Link to comment Share on other sites More sharing options...
ovenfood Posted September 23, 2011 Author Share Posted September 23, 2011 why are L6's being sent here we have too many already Quote Link to comment Share on other sites More sharing options...
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