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Engine Tech Technical discussion related to all relevant engines such as KA, SR, RB, CA, 2JZ , L24/26/28, VG, VQ, and LSx series. |
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10-22-2012, 02:47 PM | #1 |
Zilvia Junkie
Join Date: Aug 2006
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Another compound turbo RB25
This is a thread to show my compound setup I built last winter. I would like some constructive critisism if anyone sees anything or can think of anything.
The car had a series 2 RB25 that cracked #6 piston, typical i know haha. On to the details of the new setup... NEO RB25 block CP pistons Spool rods ACL bearings ALL ARP stuff Cosworth head gasket Tomei type b cams/stock gears Greddy timing belt N1 pumps with crank collar fix valve springs from Spool stock ignition medium sized old school Greddy intercooler Bosch 044 intank -8an feed -6an return FiveO 1400cc injectors garrett gt2871r ball bearing with a tial 44mm Borg Warner S259ET with a tial 38mm manifold built by me with all schedule 11, 1 3/4" stainless. Now, onto some pictures... Old engine coming out Bad piston compound setup New engine in, with new engine bay paint, all holes welded shut too Now, on to the dyno stuff. the car was run at 22 psi. this is my street tune with aem ems series 1 with e85. i am installing a surge tank and second pump because my single 044 will not support any higher than 22psi. now, if anyone who is familiar with tuning ignition with e85, please take a look at this and let me know what it looks like. Thanks, jason Last edited by 240sxrb25; 10-22-2012 at 03:43 PM.. |
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10-22-2012, 03:42 PM | #3 |
Zilvia Junkie
Join Date: Aug 2006
Location: omaha, ne
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haha, its all i can do, i did this all in my condo style apt. and all i have is a mig.
its held perfectly fine all summer of beating on it, and glowing red on the dyno. thanks |
10-23-2012, 07:43 AM | #4 |
Zilvia FREAK!
Join Date: Nov 2008
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I really like compound setups. Im sure I will end up building one at some point or another for myself, or maybe start building one over time just for the heck of it.
Personally I think I would have liked something slightly smaller on the bottom turbo, maybe a 28rs, something that would spool quicker yet have the same compressor capabilities since your waste-gating large enough from it to the top turbo. I think with that the graph would look nothing but better and fatter. |
10-23-2012, 11:04 AM | #6 |
Zilvia FREAK!
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I didnt even bother with commenting on the timing map because it was mentioned that it was just a street tune and because he mentioned that his pump isnt keeping up.
I would think with dyno tuning that the timing could be increased quite allot but it is hard to tell what is going on back pressure, egt, and iat wise unless it is logged with these compound setups. I would be interested in seeing that data as well. |
10-23-2012, 11:10 AM | #7 | |
Zilvia Addict
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Quote:
i would have dropped the psi levels to get the timing right. if you havent gotten the second pump yet get a DW or Aero 300+ pump. i run a single DW and have lots of headroom still
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10-23-2012, 11:19 AM | #8 |
Zilvia FREAK!
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yea, personally I wouldnt bother putting a car on a dyno so I could see what I made power wise with a street tune.
That would be like cutting a board and THEN measuring it to see if it will fit. He has an 044 in tank, which leads to some different options with how he wants to add a surge tank. The 044 is over kill big time to feed a surge tank, so he can get a high flow low pressure pump, or even a stock pump should flow enough, or a 255 in tank, and then get a 2nd 044 to pump out of the surge tank. That rout can cost some $$ too. I dont really like the idea of having 2 different pumps flowing out of the surge tank. |
10-23-2012, 11:44 AM | #9 | |
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Quote:
are you running a surge because the car is road racing?
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10-23-2012, 05:29 PM | #10 |
Zilvia Member
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You could also try a .64 a/r exhaust housing on the small turbo to get more spool if you wanted. Thats what i put on mine and it works well.
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10-24-2012, 05:11 PM | #12 |
Zilvia Junkie
Join Date: Aug 2006
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i will probably be trying a new housing for the gt28, that sounds like a good idea. would you guess the difference will be pretty noticeable as far as low end power? i would like to see a little faster spool. i just didnt want a huge turbo size difference.
also the reason i want to do a surge tank is because even in town if my tank get to 3/4 or 1/2, it cuts out and goes lean with a fuel pressure drop around corners....not even really bashing on it that hard. as for the surge setup, my plan is to replace the intank 044 with a smaller pump and probably do dual pumps to the rail, from the surge tank...just because ive already experienced pressure drop on a dyno with a single 044. last, the only time my car was on a dyno was a dyno day, 3 runs is all you get, lots of cars. it was really just a "see what you made" day. i have yet to tune the car "fully" on a dyno. thanks for all the tips and comments! |
10-24-2012, 05:20 PM | #13 |
Zilvia Member
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The housing will make a differance. Mine is fully spooling the 2871 at 3500 with no boost controllers. I figure i can get a few more spool rpm with controller.
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10-24-2012, 05:37 PM | #15 |
Zilvia Member
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Also those short intake runners dont help low end torque. They are geared more towards a top end powerband. Cut the manifold runners and weld in a inch or two of equal size thick wall tubing. The more the merrier. The turbo will fill in the top end.
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10-30-2012, 06:53 AM | #19 |
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Hmmm interesting setup here, I'm curious about a couple things:
Why did you use 1.75" tubing for your manifold? That is definitely hurting your spool times. Why did you pick two turbos that are so close together? For me a compound setup is about getting a big turbo online faster with a smaller one. What size A/R is on your S259? Looks like the Bullseye .70, which is much too small to support the flow of an RB+2871R, and I think you're going to run into backpressure problems if you turn the boost up. What do you have the wastegates set on right now? Oh and you should definitely switch to the smaller A/R on the 2871R.
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11-02-2012, 10:38 AM | #22 |
Zilvia Junkie
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i am actually going to throw a smaller a/r turbine housing on the gt28 and over winter do a larger pt ball bearing turbo on, but im open to suggestions of which one.
i realize that i couldve used smaller manifold piping but this setup spooles SO much faster than the single setup. any suggestions on what larger turbo to use? thanks |
11-02-2012, 11:23 AM | #23 |
Zilvia Member
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What are your goals with the car? Road race, drad race, drift? Right now (with the smaller a/r on t28) the car would be a killer road race car due to the braud flat powerband. If you put too large of turbo, it will create a second torque peak and break traction. If you want drag race there is no need for compound as you only use the top end power band. Drift seems to love compound with second torque peak. You get low end grunt to drive off the line, then when you clutch kick you land on a pile of touque and chong out.
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11-02-2012, 11:57 AM | #24 |
Zilvia Junkie
Join Date: Aug 2006
Location: omaha, ne
Age: 31
Posts: 451
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idk, i figure i can put a larger turbo on it thats a good ball bearing unit that way its picks up like the turbo i have now, but is capable of much more. im just going for a high hp number for now. i live in NE so drift isnt exactly a good goal. except for my daily commute to work lol. i like hitting the drags though.
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