Guest Anonymous Posted November 16, 2000 Share Posted November 16, 2000 We're all in trouble now! Anyone got an opinion on those sds systems? How are they in the bang-for-the-buck category? What about performance? My l28 has approximately 9.5:1 compression ratio now, assuming the stock gasket is 1.25mm, a 2.0mm gasket will give me around 8.7:1 compression ratio, which is easily turbo-able. Anyone got an opinion on how much power an 8.7:1 l28 would make with a huge turbo and intercooler on pump gas? All I'd have to buy are the manifolds, sds, and a turbo and bolt it all together. On the other hand, with the v6(which will cost a similar amount to buy and install), I'd be stuck with a wheezing undersized turbo and tiny injectors that would limit it to a bit under 300 horsepower. More power will be very expensive(expensive jwt stuff, big turbo, injectors, etc, etc, etc). I'm pretty sure the l6 will get over 300hp even with such high compression, no? Should I need to lower compression more I could just slap on a turbo head(which has more volume than my n42 n47 whatever head) right? The l6 also only has about 10k miles on it, which is nice, but it's almost 100lbs heavier than the v6, but I can live with that if necessary. Opinions? ------------------ Morgan http://z31.com/~morgan/s30 http://carfiche.com Quote Link to comment Share on other sites More sharing options...
Drax240z Posted November 16, 2000 Share Posted November 16, 2000 Morgan, I really think that you'd be better served in the grand scheme of things to find yourself a P90 head from the very start. 8.7:1 is getting on the high side, and as I am sure you know, the N42 bowl design isn't anywhere near as good as the P90 design for preventing pinging. I would shoot for ~8.3:1. I think if you use flattops with a P90 head and a 2mm headgasket you are pretty close. As far as SDS goes it is by far the least expensive programmable EFI system out there. From the 3 people I've talked to with it, quality is extremely high. You give up things like data logging and so on when you go with this system over another system, but for me I'd rather save the $1000. (plus the price of a laptop too) For a street driven car I'd go with the SDS for sure. (and I am) If I was track ONLY, I would spring for a more intense system, so I could ponder over datalogs until I was blue in the face and try to figure out where I could pick up every single little bit of power. If your shortblock is in that good of shape, I'd say go for it! Buy a turbo engine and swap what you need. I know you can get a pretty penny for the webers and the prepped N42 as its a desireable combination. ------------------ "Gimme Fuel, Gimme Fire, Gimme that which I desire" -Metallica Drax240z 1972 240z - L28TURBO transplant on the way! http://members.xoom.com/r_lewis/datsun.html Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 16, 2000 Share Posted November 16, 2000 Well, I checked around and couldn't find anybody interested in buying the whole drivetrain, which took me by surprise. Everyone wanted to buy just the carbs The more I think about it, the more I want to do it - I have some nice injectors already, and the only thing that I can't do myself in my driveway is drilling accurate holes for the magnets. It'll be cheaper too I think, not require cutting things up, and much faster. The only bad thing is the extra 80-100 pounds it leaves me with I figure what, $2k for the sds, turbo, and misc. doodads will do it easily. You think 8.7 is too high? It obviously won't take sky high boost, but I figure it oughtta be able to put out 300hp or so pretty easily, no? Is the hydraulic or non hydraulic turbo head better? Any idea what kinda compression it'll leave me with if I just pop it on? I got some kinda NisMo pistons, I know nothing about them at all. The bowl volume of the n42/n47 is like 44cc, the p90 is 56 or something isn't it? I think i can live with an extra 100 pounds to get all the benefits possible. ------------------ Morgan http://z31.com/~morgan/s30 http://carfiche.com Quote Link to comment Share on other sites More sharing options...
clint78z Posted November 16, 2000 Share Posted November 16, 2000 This should answer most of your questions, 8.7 is a little high for pump gas on the L6 the head design isn't as good as newer turbo vehicles . 8.3 should be about right you won't gain much power by .5 of a compression jump . Got to zdriver.com downloads for the engine builder Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 16, 2000 Share Posted November 16, 2000 I don't have windows thankfully. Someone port it to unix for me. ------------------ Morgan http://z31.com/~morgan/s30 http://carfiche.com Quote Link to comment Share on other sites More sharing options...
Arif Posted November 16, 2000 Share Posted November 16, 2000 Morgan, I have the complete SDS system and it does everything I need it to do. Like someone else said earlier it doesn't have the data logging capabilities but you get the best bang for the buck with this system IMO. You would be better off with the P90 instead of the P90a. I went with the P90 and it flows pretty well. A lot of people have told me that the P90a's hydralic lifters are a pain to mess with. I talked to James T. when I was deciding on what ratio to run. He said 8.5:1 was better suited for a full race turbo motor, so I would figure that 8.7:1 would be on the high side. I went with 8.0:1 if you were wondering. Just my .02 Quote Link to comment Share on other sites More sharing options...
Drax240z Posted November 16, 2000 Share Posted November 16, 2000 Morgan, if your Nismo pistons are flattops like the stock flattops, and you pop on a P90 head with a stock headgasket, your CR will be around 8.5:1. With a 2mm headgasket, it'll end up at 8.0:1. I too recommend using the P90. I have heard that replacement hydraulic lifters for the P90a are hugely expensive, and I've also heard that they can break apart at sustained high rpms. I can't confirm either from 1st hand knowledge however. ------------------ "Gimme Fuel, Gimme Fire, Gimme that which I desire" -Metallica Drax240z 1972 240z - L28TURBO transplant on the way! http://members.xoom.com/r_lewis/datsun.html Quote Link to comment Share on other sites More sharing options...
Modern Motorsports Ltd Posted November 17, 2000 Share Posted November 17, 2000 just my general .02c non turbo comment... I'd certainly pull my head and verify piston specs/deck height/headwork (if any) BEFORE committing to any other parts since your setup's been hinted at having had some work done...we never do know what the owner did or even a builder to make things work as he did...if you weren't putting the boost on it or trying to tap it's potential I wouldn't worry, but good to know your basics are as assumed.. Quote Link to comment Share on other sites More sharing options...
Guest pauli Posted November 17, 2000 Share Posted November 17, 2000 morgan, it might well run under wine. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 17, 2000 Share Posted November 17, 2000 Arif: How you like the sds? Does it run the engine nice and smooth? What kinda injectors you using? I have a set of JWT 420cc injectors I will use if I go the turbo l6 route. I really like the adjustable everything and lack of an AFM and o2 sensor. Very cool indeed. Drax: They're NisMo pistons, that's all I really know. He said compression was right around 9.5:1...... It has what appears to be a stock headgasket.. Looks like 2 metal sheets pressed together, definately not a copper headgasket. I'm not worried about getting it really really low, just low enough for 10psi or so. That'll make it a monster even when not in boost I hear the turbo blocks have more metal in them.... is that really necessary? I imagine a non turbo block will take a bit of boost no problem, right? I will not have a hydraulic lifter head either, don't worry ------------------ Morgan http://z31.com/~morgan/s30 http://carfiche.com Quote Link to comment Share on other sites More sharing options...
Drax240z Posted November 17, 2000 Share Posted November 17, 2000 My personal opinion is that the P90 with a 2mm headgasket should work nicely. The same setup you have with stock flattops would produce 9.8:1 with a stock headgasket. If in fact the nismo pistons are the same shape as the stock flattops then the P90 and 2mm puts you at 8.0:1. If it turns out the pistons have a slight dish to them, go with a 1mm headgasket. I've read that the turbo block is nice to have, but not necessary. I would say if your goal is 300hp an NA block would be ok, but for 400 or more the added rigidity of the turbo block would be benefitial. Those injectors you have should definately support over 300hp. Just remember that if you decide you want a 400hp engine you need to address the block issue. (and forged pistons, etc) I believe Scottie said he was running around 275-290hp with his L28. I believe it had the stock bottom end. (Scottie?) I'm confident that I can see 300hp with the stock (turbo) bottom end. Worst case scenario is that you blow up/melt your bottom end and have to find an used turbo shortblock somewhere and slap your goodies onto that. ------------------ "Gimme Fuel, Gimme Fire, Gimme that which I desire" -Metallica Drax240z 1972 240z - L28TURBO transplant on the way! http://members.xoom.com/r_lewis/datsun.html Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted November 17, 2000 Share Posted November 17, 2000 Morgan, if you are considering SDS, I assume you have spent some time at their website. If not, tell your other half you will be tied up for some time, snuggle up to the computer and absorb the information they have to offer. There are quite a few L28Ts running SDS but I am not sure if any has documented their experiences. You can check out my experiences with the SDS on a L28T at: http://www.mindspring.com/~vscott911/scotties240zt.htm I also agree that 8.7:1 is a bit high for pump gas but it depends on your discretion. Bottom line is that you tune that setup to the point of detonation then back it off. You will absolutlely need the flexibility of a programmable system but your limiting factor in making HP will be octane, or lack of it. ------------------ Scottie 71 240GN-Z http://www.mindspring.com/~vscott911/gnz.html Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 17, 2000 Share Posted November 17, 2000 OK, so I'll just do the p90 head for sure then, and maybe a thicker head gasket depending on how the pistons look. The thing weighs barely over 2200 lb now, so 400+ horsepower is far more than adequate. 350 is a pretty good number I guess.... Yes, I've read all their manuals. Twice. Not a big deal at all, or at least it doesn't appear to be to me. Hell, drilling a few holes for the magnets is the hardest part! ------------------ Morgan http://z31.com/~morgan/s30 http://carfiche.com Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 17, 2000 Share Posted November 17, 2000 So you had the F huh? I was thinking of getting the E and using the msd box, thus having a nice rev limiter instead of the harsh fuel cut of the sds. What'd you do with your sds and engine scottie? Anyone got a p90 head for sale? ------------------ Morgan http://z31.com/~morgan/s30 http://carfiche.com Quote Link to comment Share on other sites More sharing options...
Drax240z Posted November 17, 2000 Share Posted November 17, 2000 I threw around thoughts between the E and F systems for a while too before finally deciding on the F. Now I've just looked at their site again and noticed that the F system has gone up in price... $1300 Ouch. I may yet go with the $962 E system. Scottie, are the coilpacks worth the extra $350 in your opinion? ------------------ "Gimme Fuel, Gimme Fire, Gimme that which I desire" -Metallica Drax240z 1972 240z - L28TURBO transplant on the way! http://members.xoom.com/r_lewis/datsun.html Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted November 17, 2000 Share Posted November 17, 2000 Dont know that I could honestly say there is a $350 improvement, but appearance is important to me and it sure cleans up the engine bay. The stock L28T engine bay is not a pretty sight with that AFM, fuel rail, intake and distributor with the wires running over the valve cover. If looks is important to you, then there is something to be said in these pics, mine and my buddy. Quote Link to comment Share on other sites More sharing options...
clint78z Posted November 17, 2000 Share Posted November 17, 2000 Just to pop a little note in here about high compression turbo cars . Some of the new cars are trying this and only a few really well sorted out ones really succeed . Ie some try and run a 9.5:1 CR and the have to back timing way off so they lose their bottom end response anyway . When the could probably do an 8.5 CR and run more timing and have better low end plus way more up top . Don't forget Scottie's HP was at the wheels and was an awsome . Remeber Morgan that the head on the L6 is not as good as the VG30ET but it has a good strong bottom end . Steve Webb pulled an honest 300hp out of a flatop junkyard motor with his shaved P90 head . Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 17, 2000 Share Posted November 17, 2000 Woah. Scottie's 275 was at the wheels? Damn! That's plenty for me! (For starterrs anyhow) I guess if you factor in the cost of a msd box (What, $100 or $150) and a coil(Another what, $50 or $100) it approaches the price difference between the E and F systems. So why not get rid of the distributor for an extra $50 or $100 right? Any more bright ideas? I'm about 1/2 inch away from starting to look for a p90 head and an FI manifold and a turbo manifold...... ------------------ Morgan http://z31.com/~morgan/s30 http://carfiche.com Quote Link to comment Share on other sites More sharing options...
Guest scca Posted November 17, 2000 Share Posted November 17, 2000 i have a full turbo motor i am parting out. havent looked to see what head it is though but have everything so far. i bought it so i could rebuild it and then install and leave my car running. i only wanted the block and turbo for spares. ------------------ Mike mike@fonebooth.com http://www.fonebooth.com/brakes.html raceparts and brake upgrades. Quote Link to comment Share on other sites More sharing options...
Arif Posted November 17, 2000 Share Posted November 17, 2000 Morgan, I am running 370cc injectors on mine (upgrade later) and it runs great. A friend uses 550cc injectors with the SDS and he has no problems.I was tired of messing with the AFM as well. When I started this project I didn't want to do anything twice so I opted for the F system instead of piecing together a MSD etc. I have no regrets paying extra for the coil. I had a friend drill the holes for the magnets, however the most important thing is to scribe the pulley correctly. This system is really too easy to hook up, it is as advertised "simple"in the way of installation. Good luck Quote Link to comment Share on other sites More sharing options...
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