rreford Posted January 16, 2001 Share Posted January 16, 2001 First post, and may I say 'Thank You!' for all the fine info posted on this site!! Been reading for about a month. Most of my questions stem from reading the Corky Bell book and thinking about applying that knowledge to a straight-six Z. I plan to build turbo L28 and use aftermarket engine management. I apologize if I'm asking questions that were recently answered - I tried to read everything that seemed applicable to my situation. Thank you in advance for any input/feedback! My questions: Small intake runners (and, I presume, small intake ports) are best for off-boost performance. Has anyone tried to use a Maxima N47 in a turbo application for that reason? I don't have the cc numbers to do a compression ratio calc, but I'm guessing that the Maxima N47 would be too high in compression to make it worthwhile. What cylinder head is most popular for this type of setup? I've got an N42, N47, P90, and Maxima N47 to choose from, and I can certainly find other models! Corky says conservative cams are best for turbo applications. Does everyone tend to run stock profiles, or slightly modified? Corky recommends finding a turbo combination that gives you boost at 30% of redline (best combination of response and high RPM performance), which is ~2000 rpm on an L28. Is that what you guys with the T3/T4 hybrids are getting? I'm not sure how the emissions testing will go on my setup. It will be a '71 240 with an '81 L28 block. Do those of you who run aftermarket engine management systems (I'm leaning towards the SDS) find it easy to tune around emissions requirements? What size compressor bypass valves would you recommend for a turbo L28 running 12 psi boost? How are you routing your water supply to the turbo bearing cooling jacket? Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted January 16, 2001 Share Posted January 16, 2001 Don't take everything corky & co. say as gospel. Small intake runners/valves/etc. give more power at lower engine speeds(to a point of course). Boost has nothing to do with it. p90 is generally the best for turbocharging by far. Corky says that because he doesn't know what turbo cams are! An aggressive cam intended for a non turbo engine will blow dead goats on a heavily turbocharged engine, which is what he's talking about. A cam ground aggressively with the intention of being used in a turbocharged engine is worth the time and effort. JWT knows what they're doing in this department(and their prices reflect that!) Boost at 30% of redline will leave you with a peaky turbo that will never make major horsepower, it will wheeze out at higher speeds and boost levels. Talk to a reputable turbo vendor once you decide what you want the car to do and they can make a good reccomendation. If you don't want major horsepower, then a slightly smallish turbo is good as it will get you better low-rpm boost. t3/t4 is a pretty broad range of turbos, from a wheezing tiny thing up to turbos too big for a 2.8 liter engine. t3 and t4 are just general "classes" of turbos, there are countless variations of each(like nissan is a type of car, there are many different models). You will need either new fuel/ignition system or spend major buckage on JWT stuff to make major power reliably and efficiently. I would reccomend stand alone something, as you won't ever outgrow it and it's adjustable. JWT stuff is very nice and works great, but it's just not adjustable. That lack of adjustability might be a benefit though, if you don't want to mess with tuning things. 12psi is fairly meaningless... How much power that will make depends on your turbo... 12psi on the stock turbo isn't much, but on a larger turbo it could be a whole lot of power. I'm using OE bosch recirculation valves, 1 or 2 of those are plenty adequate for most people. My turbo isn't water cooled - just more plumbing and more connections to leak. Water cooling isn't necessary as long as you don't abuse your turbo and turn it off while it's glowing. Plus it adds heat to your cooling system, which will already be taxed with so much power to dissapate. ------------------ Morgan http://z31.com/~morgan/s30 http://carfiche.com Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted January 16, 2001 Share Posted January 16, 2001 No, t3 is a standard flange pattern. The nissan t3 housing differs in the bolt pattern on the outlet side where the wastegate bolts up to it. Not only a/r ratios, but there are literally hundreds(if not thousands) of different turbines and compressors in each category(ie. t3, t4, whatever). Factor in a handfull of different exhaust housings and a few dozen different compressor housings and you have a lot of combinations real fast. Also you don't have to use a garrett turbo.... there are kkk(my personal favorite manufacturer), mitsubishi, ihi, warner-ishi, and a few other major brands. Nissan uses garrett, porsche uses kkk, mitsubishi uses mitsubishi mostly(Surprise!), so on and so forth. Garrett are just the most common by a mile. You can also get things like t4 exhaust housings with a t3 flange, allowing you to have a full t4 turbo on a manifold with a t3 flange. Some mitsubishi flanges are the same as t3 flanges as well. There are also adaptor flanges available. And then you can get fancy internals, such as ball bearings, 360 deg thrust bearings, water cooled or dry, etc, etc, etc. But what it comes down to is you'll likely end up with a t3/t4 hybrid turbo with no fancy stuff. Probably a t04e compressor of some sort or another in either a bored out t3 housing or a E housing, and a mid-range t3 turbine in a 0.63 a/r housing for around $600, give or take. ------------------ Morgan http://z31.com/~morgan/s30 http://carfiche.com Quote Link to comment Share on other sites More sharing options...
Drax240z Posted January 17, 2001 Share Posted January 17, 2001 Cams: Stick with the stock cam. You can spend the money on a fancy custom grind turbo cam, but unless you are really pushing the edge for performance, your money is likely better spend elsewhere. The stock cam will easily support an engine over 400hp. Depending what you want out of your engine, I would reconsider wanting a turbo that starts producting boost at 2000rpm. As Morgan states, you are going to be wheezing at high rpm with a turbo like that. I am not sure how most people have their T3/T4's set up. Depending on your A/R you can end up with low end or high end boost as you wish. Probably best to talk to the place selling you the turbo about this. One thing you sortof touched on. The P90 head is probably best for the turbo application, but the 7.4:1 CR isn't! I'd look into trying to get an 8.0:1 CR or so, but honestly I don't really know a good method to hit that number. Custom pistons would be nice! ------------------ Drax240z 1972 240z - L28TURBO transplant on the way! Drax's 72 240Z Turbo Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted January 17, 2001 Share Posted January 17, 2001 Another thing to consider.... when you get your turbo, if you use standard t3 exhaust housings(instead of the propietary nissan specific housings) you can easily, quickly, and fairly cheaply change housings to get different a/r ratios and increase/decrease spool up time significantly. Another thing to consider is 'growth room'.... nothing sucks more than paying good money for a nice turbo, only to find out it's not enough turbo for what you want later. A larger turbo will also not spin up as fast, helping to not aggravate traction problems which you will have with all but the most mundane turbo engine. And whatever you do, spend every penny you can on the most efficient intercooler you can get your hands on. Don't skimp, intercoolers are one of the few things where overkill is good, not bad. ------------------ Morgan http://z31.com/~morgan/s30 http://carfiche.com Quote Link to comment Share on other sites More sharing options...
rreford Posted January 17, 2001 Author Share Posted January 17, 2001 quote: Originally posted by Morgan: Another thing to consider.... when you get your turbo, if you use standard t3 exhaust housings(instead of the propietary nissan specific housings) you can easily, quickly, and fairly cheaply change housings to get different a/r ratios and increase/decrease spool up time significantly Does using the standard T3 housing create an issue with bolting up to the stock exhaust manifold? I realize now that I wasn't too specific on the T3/T4 hybrids. Are there endless A/R combinations possible with this model? Thanks! Quote Link to comment Share on other sites More sharing options...
jeromio Posted January 17, 2001 Share Posted January 17, 2001 As far as emissions go, with a 71 you are scott free. The inspection will merely verify that your car is road worthy (lights, horn, tires, etc...) - they won't even bother measuring emissions. And in NC, there's no visual, so, you don't even have to pretend to have controls (pumps, exhaust recirc, catalytics, etc) on the car. Quote Link to comment Share on other sites More sharing options...
rreford Posted January 18, 2001 Author Share Posted January 18, 2001 quote: Originally posted by jeromio: As far as emissions go, with a 71 you are scott free. The inspection will merely verify that your car is road worthy (lights, horn, tires, etc...) - they won't even bother measuring emissions. And in NC, there's no visual, so, you don't even have to pretend to have controls (pumps, exhaust recirc, catalytics, etc) on the car. I thought that you might have to go with the emissions requirements set out for the engine year, but I can't imagine that an inspector could even tell the difference in an L24 and an L28. Thanks for the great news! Quote Link to comment Share on other sites More sharing options...
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