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
http://i33.photobucket.com/albums/d8...ps173323c0.jpg

Bad piston
http://i33.photobucket.com/albums/d8...pse5e5de3e.jpg

compound setup
http://i33.photobucket.com/albums/d8...psb9bdca42.jpg
http://i33.photobucket.com/albums/d8...ps68404df9.jpg
http://i33.photobucket.com/albums/d8...ps835bc286.jpg

New engine in, with new engine bay paint, all holes welded shut too
http://i33.photobucket.com/albums/d8...psd717dfee.jpg

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.

http://i33.photobucket.com/albums/d8...pscb6e7b9d.jpg
http://i33.photobucket.com/albums/d8...ps12136950.jpg
http://i33.photobucket.com/albums/d8...ps863ab6ae.jpg


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.

http://i33.photobucket.com/albums/d8...ps8653abdf.png

Thanks, jason

all that great fab work, and you mig welded it :( good numbers and nice setup though.

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

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.

i hope its all braced up good penetration i hope.

why such a high drop off in timing at 19-22 you can run a lot more

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.

seen it strapped on the dyno so figured it would be cleaned up.
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

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.

agreed im not a fan of dual pumps but if your going to do it i say double pumper intank.
are you running a surge because the car is road racing?

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.

Oh god that torque! Awesome.

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!

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.

Well in 3rd or 4th I hit 20lbs just after 3500 so I guess we could try it out

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.

What gear were dynoing in? Looks like full spool was at 3900.

It was 4th gear. He Had me get it up to speed then floored it. We should have to mashed it out of the hole...

Well it sounds like your good to go then. You and me both have some fuel work to do next.

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.

Id like to see a disco potato under a pt67

I would look into beefing up the stock ignition system as well. aftermarket coil packs and ignition amplifier would be beneficial. very nice looking setup. nice fab work.

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

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.

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.