Drax240z Posted October 27, 2003 Share Posted October 27, 2003 I figured I'd run this by you guys before I dive right in. I've decided on the direction I want to go with my build, and while most people on this forum seem to go with a big hybrid turbo for results at the drag strip, I am looking to compete on the autocross/road race track. Right now my engine specs are as follows: Stock 82 Turbo Engine SDS EM-3E 440cc/min injectors Stock T3 Turbo NPR intercooler (The small one) 60mm TB Eclipse/DSM BOV 2.5" press bent exhaust Walbro GL392 Fuel Pump Exhaust is next on the list, so don't worry about that. Lets assume for arguement that I have a 3" mandrel bent system with a nice downpipe. Let's also assume I have Yoko A032's, coilovers, illuminas, LSD, and vented brakes. So, I am trying to decide on a turbo for my build. I am not after peaky power, or big dyno numbers. What I want is excellent throttle response, a broad torque curve and a very autocrossable car. To this end, I am thinking about a T3/T04B, 50 trim, .63ar turbine, .5ar compressor, stage 3 wheel. I'd like to be an honest 300+ rwhp, and 300+ ft-lbs of torque. So the question is, does this sound like a good turbo for this setup? What rpm do you guys figure boost will come on at, as well as what should my rev ceiling be? (approximately of course) The goal was to be well into boost by 2800rpm, and be able to rev to ~6200rpm or so, giving me a really nice torque curve. I'm determined to make the nay-sayers around town here eat their words when they say turbo's aren't good on an autocross track. (plus this is what I want from my car) Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 27, 2003 Share Posted October 27, 2003 Not sure I know what a 50 trim is in a TO4B. The "B" series is designated with a letter, like H or V (that's what I have). That said, if you are after throttle response, you might consider a stock turbine (again, what I run) instead of stage 3...my boost comes on about 2700-2800 or so. And unless you get a different cam, you probably won't like spinning it to 6200. If you take a look at my dyno graph (in my personal gallery, running stock head and cam), I'm seriously compromised at that rpm. Peak torque way down low, peak hp around 5000, the hp curve is very flat, and is falling by 6000 - I can definitely feel the lack of torque up there. Of course you could improve a bit on that, but you may lose the throttle response down low. Good luck representing on the auto-x course. I don't think you'll have an easy time keeping up the torque through the braking and turning. I have a hard enough time on a tight road course, moving about 35-50 mph to a top of 90-100 mph. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 27, 2003 Share Posted October 27, 2003 FWIW I have yet to see a fast turbo'd Z at autox. I think Sleeper is right. Definitely brush up on your left foot braking. Jon Quote Link to comment Share on other sites More sharing options...
Guest scottjuly79 Posted October 28, 2003 Share Posted October 28, 2003 My T3/T4B .50/.63 is way out of control on an autocross course ( or maybe it's the driver?). I don't get full boost until almost 3500rpm and that's with a mandrel bent 3 inch downpipe and exhaust. I am using a ball and spring boost control so the boost hits pretty hard, it might respond a little softer using and electronic boost control since they have a an adjustment for boost response. I would say just rebuild the stock T3 and throw in a ball bearing center section, if you don't mind spending an extra $500. I had my T3/T4B Turbo done at westcoast Fuel injection and it was only $800 Canadian (Using my stock T3 as a core). Quote Link to comment Share on other sites More sharing options...
silicone boy Posted October 28, 2003 Share Posted October 28, 2003 Hey Nathan, What road course do you run at. There aren't that many around here, are there? Quote Link to comment Share on other sites More sharing options...
fl327 Posted October 28, 2003 Share Posted October 28, 2003 I wouldnt do anything with the turbo yet. My reasoning for this is that you have the ability to custom tailor your fuel curve to suit making power at high boost and maintain it. Yes, while the turbo may be inefficient at making power, you can make up for it in some part by being able to fuel it at high boost/rpm levels, which is something most of us with the factory fuel curves cant really compensate for as good as a standalone situation. 300hp or close to it can be done with that turbo, since you do have the fuel to support it and the ability to tune it a lot better than alot of us can. Quote Link to comment Share on other sites More sharing options...
Guest scottjuly79 Posted October 28, 2003 Share Posted October 28, 2003 How much boost would you have to push to get 300HP with a stock T3? Also how efficient would a T3 be at that boost level? I am guessing not very, plus I don't think the stock turbo moves a huge volume of air either. Ever considered using a stock T3 in conjuction with water injection? That would eliminate the problem of the T3 heating the air too much to be efficient/safe. I have heard a lot of good things about water injection from the "old school" turbo guys, but most of us younger generation really don't know much about it? anyone have any experience with it? Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 28, 2003 Share Posted October 28, 2003 Hey Nathan' date=' What road course do you run at. There aren't that many around here, are there?[/quote'] Second Creek. Unfortunately, it's closing at the end of 2004 season, with no replacement. And I would not bother with a stock T3 if you are going for 300hp. It is not efficient at all, you are much better off with a hybrid. Contrary to common thought, the stocker will not spool any faster - if you keep the stock turbine and go with a bigger compressor there will be no difference in spool time, and you will run much more efficiently and take a big heat load off your engine. Quote Link to comment Share on other sites More sharing options...
fl327 Posted October 28, 2003 Share Posted October 28, 2003 440cc and a stock turbo with a standalone-you can get dang near 300hp without spending any more than you did, thats all im saying. efficient-of course not. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted October 28, 2003 Author Share Posted October 28, 2003 Great discussion guys, thanks for all the ideas. I'm staying away from water injection and the like, not because I don't think it works. However, I want a system with zero refills, etc. (well, except for fuel) I don't want to have to worry about NOS bottles, or water bottles to keep topping up. Personally I'd rather go with an efficient intercooler rather than water injection anyway. Seems like less of a potential problem. I've got a large NPR on the way from costa rica, which I may or may not replace my small NPR with. I'm a little concerned that the extra volume will detract from the throttle response, however... I suspect with some changes to my intercooler piping and a few other tricks I can get that response back. I am under the (false?) impression that a new T3 stage 3 turbine is more efficient than the old nissan stock turbine... Am I misinformed? Quote Link to comment Share on other sites More sharing options...
Guest scottjuly79 Posted October 29, 2003 Share Posted October 29, 2003 I believe a T4 compressor would effect spool up, even if you are using a stock T3 exhaust housing/wheel. The larger T4 compressor wheel takes more force to spin because it is larger/heavier than the T3 wheel that it is replacing, therefore it would take more exhaust energy to get the heavier compressor wheel up to speed. Maybe there is a factor that I am not taking into account, but that's the way things would seem to me! Plus I can tell you from experience ( I just upgraded to a T3/T4B) that it definately takes longer to spool than my stock turbo did. As for the water injection, I have heard that most of the systems average a tank of water to a tank of fuel. Although you are right in that it is more things to go wrong, imagine forgetting to fill the tank when fueling up! I have a hard enough time remembering to put 94 octane gas in my car rather than 87. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 29, 2003 Share Posted October 29, 2003 I believe a T4 compressor would effect spool up, even if you are using a stock T3 exhaust housing/wheel. The larger T4 compressor wheel takes more force to spin because it is larger/heavier than the T3 wheel that it is replacing, therefore it would take more exhaust energy to get the heavier compressor wheel up to speed. Maybe there is a factor that I am not taking into account, but that's the way things would seem to me! Plus I can tell you from experience ( I just upgraded to a T3/T4B) that it definately takes longer to spool than my stock turbo did. Well my experience is different. My stock T3 never spooled any faster than my T3/TO4B, the biggest difference came with my 3" exhaust. The turbine is 90% of the mass of the moving parts of the turbo, and it is made of steel. The compressor wheel is made of aluminum and is very light, relatively speaking. That is why the biggest factor in how a turbo spools up is the turbine and the turbine housing a/r. Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted October 29, 2003 Share Posted October 29, 2003 I beg to differ on the spoolup issue. When my turbo went south, I had the stock turbine clipped and a S-Trim T4 compressor put on. I start spooling about 200 RPM lower than stock and it comes on quicker. The concept of the "SPORT TURBO" offsets the larger/less restrictive turbine section with air that is moving a lot faster from the compressor (greater radius). In this case it was close to an even match as to the give and take. Please note that I am runnning a complete 3" exhaust from the downpipe through cat and on back - haven't done the downpipe yet! Not only is the air moving faster it is a lot cooler than the stock compressor. The S-3 Trim is perfect for the 300-350 range. I myself got it because I wanted to raise the boost and not intercool or change injectors. I keep the same characteristics I had before the change. I also got the water cooled center section. This was all back in '94 and I've got over 40K on it since - and it has spiked to over 15 lbs on several occasions w/o pinging - thank God for the detonation sensor!. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted October 29, 2003 Author Share Posted October 29, 2003 Hey Brad, your setup sounds similar to what I want to go with. I'm a little confused witht he S-3 term.. I suspect that is your compressor wheel trim... Is this a term that is specific to one turbo company? I've always heard 50 trim, 57 trim, 60 trim, etc used... Turbine blade clipping is interesting... One one hand you'd lower the efficiency of the turbine, but at the same time you lower the mass and the inertia of the turbine... The question is, how do you know how much to clip without getting into some indepth analysis? (I realize that you get an expert to do this for you, but how do they know?) Anyone else with experience in clipping the turbine? Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 29, 2003 Share Posted October 29, 2003 Drax - TO4B trims are designated by letters. I am running a V trim, others run S or H. It's the TO4E compressors that reference trim with 50 or 57 or 60. Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted October 29, 2003 Share Posted October 29, 2003 I dont' know what you guys are doing if your spool-up is over 3k. with my stage 3 turbine, and H3 compressor, I was at full boost, 20+ psi by 2800 rpms. Now with a stage 5 I am still there by 3200 rpms, so you should be checking something. My personal position is you will get much better spool-up by ditching the stock Wastegate actuator, and running a dual port, and using a boost controller to introduce boost to the lower port for raising and lowering your boost. Also, you can put any wheel you want in a housing, but I would put an E housing on my car, and run an E wheel. If you want better spool-up, consider a .48 ar turbine housing, I had one, it will make your car brutal from a dead stop, you notice it will fall over in the upper rpms. Also you could go to the stage 2 turbine wheel, which has less mass, and as sleeper pointed out, it is the turbine that really determines spool up. I would run a 3 inch exhaust, and convert over to a mass air system, like a 300 ZXT VG30 arrangment, alot of people have that down now, and the MAF is way more responsive then the AFM. Sleeper, your issue with upper rpm power could be your turbine wheel. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted October 29, 2003 Author Share Posted October 29, 2003 I would run a 3 inch exhaust, and convert over to a mass air system, like a 300 ZXT VG30 arrangment, alot of people have that down now, and the MAF is way more responsive then the AFM. Geeze, I'm not sure I like that tradeoff at all. You think the 300zx MAF will be more responsive than the SDS? I'd thought about the .48AR exhaust housing... strikes me as being too small. I think I want to stay at the .63AR area. Lockjaw, you think I'll see a significant difference with a dual port WG actuator? Right now I am running the granger style boost controller, which helped with spool up quite a bit. I'd not expect the dual port to be better than the granger check valve/stock WG actuator setup...? Thanks for clarifying the trims sleeper, something I've been wondering for a while. For T04E compressors, 50, 57, 60 numerically larger flows more... For the T04B can I assume from smallest to largest its H, S, V? (alphabetical order) I'm sure I'm not the only one benefitting form this info, so keep it coming guys! Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 29, 2003 Share Posted October 29, 2003 Sleeper, your issue with upper rpm power could be your turbine wheel. Thanks, I'm thinking you are probably right. My engine might get really weird when I slap on my turbo cam without changing the turbo...but I already have the head built up, and no funds for a new turbo. Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted October 30, 2003 Share Posted October 30, 2003 TO4b is S, V and H, in order of smallest to largest. I do think you will see a better reponse with your boost by going to a better WG actuator, the stock one sucks in my opinion. A dual port one is nice, becasue in addition to the spring pressure, you are adding boost pressure on the bottom side of the diaphram in the housing, which helps keep it closed. When I added this turbo I got from Jeff, I had some major creep problems due to the airflow coming thru it, and it would make say 10 psi and then as you got going, it would go up to 15. This is with my dual port ones, only using the top port. When I added the bottom one it improve dramatically, as did it when I had a Stage 3 turbine wheel. thats my story and I am sticking to it. Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted October 31, 2003 Share Posted October 31, 2003 Well if you want fast spooling, then look no further. The 1988+ 300zxt's had a T25 compressor...FULL boost around 2300rpm. In my hulking pig of fully loaded stock automatic 2+2 300zxt (1988) with cat back exhaust and k&N filter, with the boost set to 9 psi with no i/c, I ran 14.6-14.8's all day long. 0-60mph in 6 flat! 8) Car was very fast off the line...the auto made it seem like it was straining (not shifting to 3rd quick enough) and held too long, i'm sure it would run low 14's with a good 5 speed. It was excellent for hole shots, or in town rolling starts...car just went..instant boost! Quote Link to comment Share on other sites More sharing options...
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