olie05 Posted December 8, 2007 Share Posted December 8, 2007 Prox, if you haven't already welded up the straight runners to the flange, now is your chance to optimize the angle of the runners... in other words make them straight, and use the 180 degree bends to space your throttles correctly. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted December 8, 2007 Author Share Posted December 8, 2007 I already welded the runners to the flange. I am going to weld in the velocity stacks in a few hours to my 4" plenum. I found an awesome 2" I.D. 180 degree fuel filler hose for $15 a piece at CarQuest!! So I can either utilize 6 - 180 bends or I can cut each piece in half and make 2 - 90 bends out of each one. MUCH cheaper then the $35 a piece silicone or aluminum u-bend. Cheapest option I found was $7 ...90 degree elbows in aluminum from Global Tech Engineering recommended from Austin.. I would buy those then a silicone coupler which is about the same price as the full u-bend itself! yes fuel filler hose is UGLY... i would prefer aluminum. but damn this manifold is getting pricey lol. $156 for 2 sets of throttle bodies shipped $80 for the aluminum sheet, 4" aluminum pipe, 1.625" runners $135 for the intake flange shipped $116 for the aluminum velocity stacks shipped Soo total is $487.. which is a bit pricey (im thinking lonewolf's intake now lol) .. and then I need possibly an additional $100 in rubber couplers/bends. Still cheaper then having a shop weld up one.. or buying other ITB setups.. and I have my own plenum for the turbo and experience gained! Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted December 9, 2007 Author Share Posted December 9, 2007 The last picture shows how the manifold will be pieced together.. using a 180 degree 2" ID radiator hose.. cheap and ghetto i know.. but it works! Quote Link to comment Share on other sites More sharing options...
Careless Posted December 9, 2007 Share Posted December 9, 2007 teh bombz0rs! i hate to show you this, now... though i will. http://www.rossmachineracing.com Quote Link to comment Share on other sites More sharing options...
TrumpetRhapsody Posted December 9, 2007 Share Posted December 9, 2007 Ok I'm almost positive this is a stupid question, but I'm going to ask it anyway because I'm curious. Looking at those pictures, even with forced induction it looks like the cylinders closest to the incoming air would get the most air the soonest, and the cylinders in the back would get diminishing returns. Is there a reason most I-6 engines use intake manifolds with this configuration, instead of the air going into a header-like manifold that would get an equal amount of air to each cylinder? I'm sure this goes into complicated fluid dynamics and such, so feel free to ignore me or tell me to buzz off. EDIT: Oh yeah almost forgot the important part: those parts look great, Props! Can't wait to see them bolted up to the Z. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted December 9, 2007 Author Share Posted December 9, 2007 I kno about Ross Machining.. I began pricing my manifold through them.. but I found some parts for MUCH MUCH MUCH cheaper than any online company offered the materials. Trumpet.. your right.. Cyl 1 and 2 will have the most air.. and 6 will get the least. unfortunately with my space restrictions I was unable to design the plenum I had originally planned, which would angle the air to the center of the manifold so all cylinders will get equal air (Look at Ron Tyler's beautiful manifold) However.. its proven with RB's, L-series motors, and 2JZ's etc can produce loads of power with the similar plenum design like I have. Quote Link to comment Share on other sites More sharing options...
Careless Posted December 9, 2007 Share Posted December 9, 2007 if you have a turbo to fill that air box with enough air, then the further cylinders will not suffer from less air.... it might while it's spooling, but once at full boost pressure, it will most likely just keep the plenum packed to the brim. I wouldn't worry about it with an HY35 Quote Link to comment Share on other sites More sharing options...
TrumpetRhapsody Posted December 9, 2007 Share Posted December 9, 2007 So basically it gets down to a diminishing airflow gain versus cost (or space in this case) ratio then? That makes sense, kinda what I was figuring. So that leads me to the next logical question (which has probably also been answered before): What are the gains expected with a custom fabbed manifold like your making here compared to a stock manifold? Obviously enough to outweigh the cost or you wouldn't be doing, so I guess I answered my own question EDIT: Careless: that makes sense too. I guess what I mentioning would affect an N/A engine more than a FI one, so it doesn't matter as much for us. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted December 9, 2007 Author Share Posted December 9, 2007 well the first improvement over stock is the larger diameter runners.. which will remove the restrictions of the stock intake.. which begins to run out of room for air after 5,000 rpm. in addition my longer runners will provide a slightly more torque at lower RPM's. with 6 throttle bodies... throttle response increases dramatically From the Science of SpeedQ: What are the benefits of individual throttle bodies? A: Individual throttle bodies allow the engine to operate more efficiently by decreasing pumping losses to achieve more horsepower. The runner length can be tuned, injectors placed at optimal positions and angles, and air flow speed maximized. The system can be tailored to the engine displacement, compression, cylinder head valve train design. A properly tuned system can dramatically improve throttle response and decrease intake tract restrictions to increase horsepower. Manufactures typically prefer the single throttle body design as the system is much less complicated and less costly to produce compared to an individual throttle body system. For more info visit this link : http://www.autospeed.com/cms/A_3049/article.html Quote Link to comment Share on other sites More sharing options...
TrumpetRhapsody Posted December 9, 2007 Share Posted December 9, 2007 Only 5k huh? Hmm, that's... going to be a problem. I see more $$$ in my distant future. Great link, that helps. I appreciate you indulging my engine-ignorant self, lol. I'm learning little by little. Hopefully eventually I'll know what I'm talking about and be able to give back to the forum. One last question, then I'll get out of your hair. Are you planning on fabbing a custom fuel rail, or will you be able to use something like pallnet's? Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted December 9, 2007 Author Share Posted December 9, 2007 Only 5k huh? Hmm, that's... going to be a problem. I see more $$$ in my distant future. huh? whatcha mean $$$ ? I will be using the fuel rail I have on the Z now.. which was manufactured from Pallnet. Quote Link to comment Share on other sites More sharing options...
TrumpetRhapsody Posted December 9, 2007 Share Posted December 9, 2007 Sorry, could have been clearer. well the first improvement over stock is the larger diameter runners.. which will remove the restrictions of the stock intake.. which begins to run out of room for air after 5,000 rpm. I was just joking about wanting to do something similar to what you're doing now if I want to get more than 5000 rpm out of the engine, and the inevitable spending of money if I do. Good to know if I get a pallnet fuel rail now I can use it if I work up a custom intake, thanks. Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted December 9, 2007 Share Posted December 9, 2007 Typically cyl. 6 runs lean on an RB or any 6 cyl. with a forward facing manifold... Even NISMO recognized this and made a plenum to replace the RB26DETT part that minimized this. Evan Quote Link to comment Share on other sites More sharing options...
Forrest Posted December 10, 2007 Share Posted December 10, 2007 Typically cyl. 6 runs lean on an RB or any 6 cyl. with a forward facing manifold... Even NISMO recognized this and made a plenum to replace the RB26DETT part that minimized this. Evan I haven't really gotten my hands dirty with the 6TB setup yet, so I don't know all the issues I will run into. But I was under the impression that you could just adjust the throttle plates to compensate for this problem. Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted December 10, 2007 Share Posted December 10, 2007 Forrest. I am not sure, but if it was that easy I would think nissan would have already done it to the rb26dett. I am no engineer though . Evan Quote Link to comment Share on other sites More sharing options...
Forrest Posted December 10, 2007 Share Posted December 10, 2007 Actually, they might have, from the factory. The problem is you have adjust them on a regular basis...and how do you figure out how much to adjust them by with only one O2 reading? Maybe I'll have to go with twin turbos just to have 2 different DP's to take O2 readings from. Quote Link to comment Share on other sites More sharing options...
aziza z Posted December 10, 2007 Share Posted December 10, 2007 looks great. cant wait to see it on the car. Quote Link to comment Share on other sites More sharing options...
Guest TeamNissan Posted December 10, 2007 Share Posted December 10, 2007 Didn't Greddy already address this issue with their rb26 plenum? Isn't that the reason it is so widely used? No need to get all off topic about it. Quote Link to comment Share on other sites More sharing options...
Guest TeamNissan Posted December 10, 2007 Share Posted December 10, 2007 It does look great though. What tbs are you using? They almost look like those dcoe fi tbs. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted December 10, 2007 Author Share Posted December 10, 2007 it is possible to tune each cylinder w a very sophisticated FMS and individual EGT probes after EACH cylinder... much like high performance aircraft use. The stock RB26 runners and throttle bodies will handle 1000 hp plus... so I have no doubt that my manifold will be plenty for my 400rwhp motor LoL I also found out that NISMO's new RB plenum did NOT have a velocity stack/air horn on the 6th cylinder.. why ... im not quite sure. In addition the available volume of air decreased as it was closer to Cylinder 6. Quote Link to comment Share on other sites More sharing options...
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