Lewis Maudlin Posted February 2, 2006 Share Posted February 2, 2006 OK, been driving my SR20DET powered 280z around. I am interested in upgrading the turbo to reduce lag. It would be nice if it was faster spooling. I do not want to upgrade the injectors and MAF yet since I am afraid I will lose MPG's. Any suggestion on a nice driveable turbo that will reduce lag and increase power? Also, when I watch my boost gauge, my boost spikes to 16 or 17 psi for a second or two before it drops to the 13 psi I am running. Should I be concerned about detonation? Is this just a gauge anomaly? If it is a problem, what can I do to fix it? I am running T25, cheapo aftermarket boost controller, greddy bov, ported polished intake and exhaust. Quote Link to comment Share on other sites More sharing options...
True School 240Z Posted February 2, 2006 Share Posted February 2, 2006 A good turbo to upgrade to would be the Garrett GT25/40R which is what I have in my '73 with an S13 SR20. I still have the stock injectors and MAF and it's running pretty smoothly with no great loss in MPG. Alex Vildini could tell you more since his shop put it in. It is a much quicker spooling turbo. It made 259 hp on the last 350Z dyno day in Wilmington, CA. I was giving those G35/350Z guys some decent competition. As far as boost spikes, mine peaks at about 10 psi before settling at 9 psi (autometer so accuracy is sketchy) I haven't heard any detonation going on, but my margin is a little closer than yours. I know you are trying to save fuel, but in my experience it's always safer to run rich than lean. BTW, how much hp is your SR pushing out? Quote Link to comment Share on other sites More sharing options...
Lewis Maudlin Posted February 2, 2006 Author Share Posted February 2, 2006 I need to dyno mine. I am hoping I am pushing close to 275whp at 15 psi. I have a red top SR20DET ported and polished aftermarket intake manifold exhaust manifold with down tube Walbro fuel pump 3" mandrel bent exhaust going to Megan 3" inlet 4" outlet muffler (silencer removed) Electric fan Mine's VX ROM ECU ACT HDSS clutch My set up is similar to Projectrb240sx who claimed to have dyno'ed in the 250-275 rwhp range. The actual only difference I think I have may be the bigger exhaust and the Mine's VX ROM ECU. It feels like 250-275rwhp. Quote Link to comment Share on other sites More sharing options...
Superz Posted February 2, 2006 Share Posted February 2, 2006 Bigger injectors and a bigger MAF dont lower gas mileage. At cruise speeds your AF ratios stay around 14.5 no matter how big your injectors are due to closed loop processing. The proper tunning has to be done though. With bigger injectors the duty cycle is much lower than stock, of course on boost with open loop your mileage will be less. Quote Link to comment Share on other sites More sharing options...
Guest asad137 Posted February 2, 2006 Share Posted February 2, 2006 The 25/40R isn't the best choice for a quick-spooling turbo. These days the hot setup for responsive 240sx's with SR20DET's is the GT2871R with 0.64 A/R turbine housing. The 25/40R's wheels are a bit too mismatched to produce the best response. Other options are the GT28R or GT28RS. Asad Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted February 3, 2006 Share Posted February 3, 2006 The spiking, and to some extent, the slow response, could be caused by the cheapo boost controller. I've never driven a 4 cyl turbo, but how much could the lag be with a T25?? Mario Quote Link to comment Share on other sites More sharing options...
Lewis Maudlin Posted February 3, 2006 Author Share Posted February 3, 2006 Don't get me wrong. The lag isn't bad. I am just a perfectionist and would like to upgrade the turbo. Bigger, faster spooling, etc. The T25 in my car probably maxes out at 13-15psi. I may want to experiment later. So, if I am considering upgrading, I might as well go with the best one for now. Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted February 3, 2006 Share Posted February 3, 2006 Your only hope of getting anything resembling near stock lag and still be bigger is with a BB turbo I would think. You do need dyno time if you think a stock SR is laggy! Dave Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted February 3, 2006 Share Posted February 3, 2006 Going to a larger turbo will not reduce lag. It takes more exhaust to turn a larger turbine wheel, hence higher RPM's... At what RPM do you see full boost? Another option may be a small shot of nitrous in order to get the turbo spooled quicker.. Quote Link to comment Share on other sites More sharing options...
EZ-E Posted February 3, 2006 Share Posted February 3, 2006 I was looking and thinking the same thing, lagging SR turbo its T25 for gods sake, and your not going to go bigger with less lag, its just not going to happen. You could possibly have the same responce as you have now though, but in the turbo world, usually bigger and less lag is a total oxymoron. It think for now your money would be best spent on a EBC and some time on the dyno, then dropping a larger turbo into the car. Quote Link to comment Share on other sites More sharing options...
240zwannabe Posted February 3, 2006 Share Posted February 3, 2006 why don't you try another s14 BB? since your other one $hit out on you, you don't really have anything to compare the T25 to. Quote Link to comment Share on other sites More sharing options...
SR240Z Posted February 3, 2006 Share Posted February 3, 2006 i dont think with stock s13 maf you can be at over 260whp unless it was tweaked. but for a faster spooling turbo with less lag, the closest you will get to that is the garrett t28 bb s15 turbo, i would definitely think about changing injectors and maf though Quote Link to comment Share on other sites More sharing options...
Lewis Maudlin Posted February 4, 2006 Author Share Posted February 4, 2006 I was under the impression that I could reduce lag by going to a BB turbo and possibly to one with ceramic. Maybe I was mistaken. Quote Link to comment Share on other sites More sharing options...
240zwannabe Posted February 6, 2006 Share Posted February 6, 2006 ceramic wheels break easy...never a good thing if you ask me Quote Link to comment Share on other sites More sharing options...
Lewis Maudlin Posted February 15, 2006 Author Share Posted February 15, 2006 The 25/40R isn't the best choice for a quick-spooling turbo. These days the hot setup for responsive 240sx's with SR20DET's is the GT2871R with 0.64 A/R turbine housing. The 25/40R's wheels are a bit too mismatched to produce the best response. Other options are the GT28R or GT28RS. Asad OK, I am thinking I am going to switch to the GT2871R. Which do I need? 0.64 A/R or 0.86 A/R? What are pros and cons? I am switching to APEXi FC with commander and Z32 MAF. The 550's will come soon. Thanks for the help Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted February 16, 2006 Share Posted February 16, 2006 A BB core does reduce the rolling resistance of the rotating assembly and yes a ceramic wheel does make said assembly lighter. All of this will not outweight the additional inertia from much larger wheels. I agree, S15 T28BB. Nice response and more hp. Dave Quote Link to comment Share on other sites More sharing options...
Superz Posted February 16, 2006 Share Posted February 16, 2006 I have a gt-2871r that will be going on my sr20det. I also have the z32 MAF with the 550cc injectors, all I need now is to get the ECU reprogrammed by RsEnthalpy at 21psi and im done. In the future I will be installing a Methanol injection kit that would enable me to run 25-27 psi on pump gas. I have a gt-35r in my Evo and it compares to nothing else. Sure there's lag up till 4500rpms, then its BAM!! all the way to 8300 rpms. The benefit of a big turbo is insane top end and that ball bearing cartridge makes for the recovery time between shifts amazingly quick. The z32 MAF is good for 600whp+ reliably and should be more than enough for most sr20s. The MAF is not a restriction as some presume. In fact it is about 3 inches in diameter with nothing to hold back hp. Im sure that at insane levels of hp (600whp+) it may become inaccurate in measuring the air intake but this is way beyond my target. The stock ECU is capable of also supporting such levels of whp, therefore I decided to stick to this recipe. Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted February 16, 2006 Share Posted February 16, 2006 The z32 MAF is good for 600whp+ reliably I think you'll find its closer to 500fwhp. http://autos.groups.yahoo.com/group/sr20transplants/message/27034 Not sure if everyone can see that so: The Z32 is just calibrated to give max reading (5V) at higher airflow. So it maxes out at about 500hp worth of air while the RB20 unit hits 5V much earlier. PL Pete Leibig runs a business remapping SR. Dave Quote Link to comment Share on other sites More sharing options...
True School 240Z Posted February 16, 2006 Share Posted February 16, 2006 What about a MAP sensor? If you get the Apex PFC (d-jetro?) Why not go MAP? Or perhaps Q45 MAF? and Asad, I like my 25/40R even though the 2871 spools faster...as they say. Quote Link to comment Share on other sites More sharing options...
Lewis Maudlin Posted February 16, 2006 Author Share Posted February 16, 2006 After careful research, I am going with the GT2871R, Z32 MAF and 550's. I figure I can get at least 350rwhp reliably and still retain my cruising mpg or at least keep it over 20 mpg. I just can't resist the extra relatively inexpensive horsepower. The APEXi standalone is on its way so I don't have to have my computer retuned and retuned. I would rather have my ECU tuned on my car anyway rather than a standard tune without my car. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.