V8KILR

I have no idea why you think the #1 turbo will be a big turbo? It is still a lot smaller then the old single turbo I had, so it will spool much quicker and make boost around 1500rpm sooner. Compounding the compressors has nothing to do with getting fast spool on the first turbo as you are only using one turbo at that point for both sequential and compounded setups.

The exhaust side of my setup is compound though, so the wastegate control needed is very similar. Surge control of the #2 turbo is why the #3 wastegate bypasses flow from the #2 turbo until such time as the #2 turbo can support the flow and pressure required to match the #1 turbo. Surge control of the #1 turbo after the #2 is online and the boost is ramped up should be automatic. This is because increasing back pressure in the mid pipe will act on the back of the #1 wastegate valve, which will increase the effective spring pressure which will close the wastegate a bit more. This will give more drive pressure to the #1 turbo as manifold boost increases. Hopefully it doesn't increase too much and over spin. It will certainly be interesting to see if it all works as designed.

Yes, the interactions between the turbos is very complex in a compound setup with the #1 and #2 turbo affecting each other as you point out. That's why I'm using spring pressure to control the #1 wastegate as that works automatically. To try and make the ECU control the #1 wastegate is extremely complex as Boost Logic (and Sound Performance for their sequential system) found out when they tried to do it. The exhaust side of my setup will act in a similar manner to how a normal compound turbo setup does. Compound turbo systems work very well when using spring pressure to control the #1 wastegate and using the ECU to control the #2 wastegate, based on the extensive reading I have done on compound turbo gas setups. The best thread on this subject is http://www.yellowbullet.com/forum/showthread.php?t=216811 and is well worth the read.

I haven't booked the dyno yet. He is usually booked about 2 weeks in advance so once I get it home (hopefully this weekend), I'll check everything over and if its all okay, I'll book the dyno then.

The rear water pipe is done and the #1 wastegate is all done and the #2 wastegate will be finished today. The down pipe should be finished tomorrow, so it's getting close now.

And here's another pic of the setup before the #1 wastegate pipe was welded on. The #1 wastegate is a Turbosmart 60mm.

Thanks. The only downside to this design is that it will run with high back pressure due to the turbine back pressure of each turbo being compounded. I have tried to allow for this by running big turbine sizes and big AR, but I can go bigger with these on both turbos if necessary. I'm also swapping to more auto friendly Kelford T202-C cams (264/272 with 9.65mm lift) and will be setting them close to zero overlap to prevent any reversion occurring. Without reversion issues, the problems from high back pressure are not too bad. The stock 2JZ-GTE runs very high back pressure of course and can be at 4.5 bar back pressure at 1.5 bar boost, which is a 3:1 ratio. If mine goes over 3:1 (I will be measuring it), that will be the time for turbine and/or AR changes to make sure the EGT does not get too high.

Good news, the bonnet closes easily with 1-2 cm clearance above the rear turbo compressor housing with the turbo bolted in position. The rear turbo air intake also fits under my existing TRD strut brace, so that's two of my fabrication goals achieved.

The original design did have a swing check valve and I actually bought a 2.5" brass one to use so that's the backup if the wastegate does not work, but I decided to try the 66mm wastegate first. What issues do you see with the design?

Some more pics:

My sequential turbo build has started:

I spent an hour or two yesterday port matching the ports to my spare exhaust gaskets on the SPA manifold. Also ported out the T4 flange to my undivided T4 gasket as well so that's all ready. I also have bought just about all the parts I need including the Turbosmart wastegates and MasterPower turbos I will be using. Currently trying to find a local workshop that will fabricate the exhaust pipes and compressor pipes as per my latest design. It's been simplified a bit which should make it a lot easier to tune.

Finally got the SPA manifold. Overall I'm pleased with the casting. There are 3 places where it would need tidying up, but I guess you get that with most cast manifolds. The wastegate hole is not round and is 32mm on the short side and 34mm on the long side. I'll port it out to an oval hole of around 50 x 36mm, but I won't be using it initially anyway. The T4 flange hole is not rectangular and is 75mm at the wide part and 68mm at the narrow part. The height is 52mm. I'll be porting this out to an oval shape around 85 x 65mm for extra flow to the #1 turbo and the 66mm wastegate.

The big 66mm wastegate in the pic is what limits the flow through the first turbo. If the first turbo starts choking before it reaches full boost, to fix this you just open the wastegate slightly (say 5%) while still allowing enough flow to keep boost increasing. By doing this if needed, it will limit EGT and back pressure. The stock system of course chokes the engine way more on the first turbo then my setup ever will, so would have even more back pressure and higher EGT. If it works as designed, it will be an awesome dyno curve similar to what a 6L 2JZ engine (if such a beast existed) would make. This is because once the first turbo is at 15-20psi, it will spool the second turbo just like it is a 6L engine.

I presume you mean between the two turbos. I did consider using a 3.5" exhaust pipe there, but as you say it does get re-compressed to go through the #2 turbo anyway, so its probably not an issue. The 66mm Precision wastegate will bypass all the exhaust gas that is not required to keep the #1 turbo spooled up, so EGT shouldn't be much different then it would on a single turbo setup? If I get carried away, I may log exhaust temperature or pressure in the SPA manifold just to see if there is an issue there. I don't know of any large sequential setups apart from the couple of 2JZ ones done by Sound Performance in the USA. Are there other ones as well?

I anticipate really bad headaches ......................................... from the high boost and huge g forces it will launch with. My setup is not compounded on the compressor side (as the compressor side is sequential), so it will only be running up to about 35 psi boost. It uses the same exhaust setup as a compound setup does, which is where the compound part of the thread title comes from.

Ball bearing turbos only gain around 200rpm of spool over plain bearing turbos. Where ball bearings are of most benefit is for high thrust loadings and improved off boost to on boost response at higher rpm. This setup of mine should spool only just a few hundred rpm slower then factory turbos as I'll also be running a QSV on the #1 turbo. This will be about 1500rpm better spool then what I have at the moment. It is anticipated that max power will be around three times what a factory setup is capable of.

Looking to have similar turbo positioning to the Boost Logic compound setup. http://www.nissansilvia.com/forums/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=232496

There are two wastegates. The second one is my existing one that I'm reusing which is at the bottom end of the yellow pipe, so I didn't bother drawing it in. The drawing may be slightly out. The rear turbo will fit under the bonnet without any mods, but it may have to sit a little lower then the drawing shows.

To keep the setup simpler to make, lower cost and to make the fitment easier, I have decided to use a SPA cast manifold as the manifold part of my setup. It's in the country now and is just waiting custom clearance. It may limit max power a little bit, but with the way I'll be using it getting 1000whp will not be an issue. This manifold has previously made well over 900whp on a single turbo setup. I'll port the wastegate hole out to 45mm (about the max it will take) but initially I will just bolt a cover plate on it as the T4 bolt stud pattern part of the manifold (after more porting) will be used to feed the #1 turbo and also the Precision 66mm wastegate, which will feed the #2 turbo. The 45mm wastegate port will only be used to feed the #2 turbo as well, if the back pressure in the manifold gets too high. The Precision 66mm wastegate has also been ordered and is on its way. Here a rough scale mockup of how it will all fit together using the SPA manifold and the Precision 66mm wastegate. Done with Paint, so definitely not Photoshop quality. This is as per my original design (without an EGCV) which I'll try first. Edit: drawing updated to match engine bay measurements.

Here's the part number for the pins: 866225025C3C PRO PIN:866x2.250x250/22mm

Here is why I'm upgrading my std CP wrist pins. http://www.supraforums.com/forum/showthread.php?707377-WARNING!-10-1-CP-Pistons-come-with-weak-wrist-pins Using a quote from Top Gear, "It's like asking a submarine captain how deep his submarine can go. Until he actually takes it to the point the hull crushes, he doesn't know." Personally, I think the stock crank will fail long before the BC rods give way.

Based on the website, the rods are identical and it only the rod bolts that are different. They sell the ARP625+ rod bolts separately now which they didn't used to either. I read up a lot on it but there is no proof that it is of any benefit that I could find. For most girdles, you machine the tops of the main caps flat so the girdle provides support to the center of the caps as well, which the MVP one does not.

Change to the ARP625+ rod bolts with your BC Sportman rods and you will be fine as that's then the same as the Brian Crower Pro Series Rods. The piston wrist pins are even more important as the stock CP pins are not strong enough, so make sure you upgrade yours to the CP PRO PIN 2.250. Are you still running stock main caps? If so then 1100whp is getting to the level where you should be thinking of billet main caps as well. I currently run the Brian Crower Pro Series Rods and I will be doing the CP PRO PIN 2.250 and billet main caps this year in a new twin 61mm (equivalent to an 86mm single) turbo setup.

The ACL main bearings that I used were all the same size.