V8KILR Posted June 8, 2014 Author Share Posted June 8, 2014 My sequential turbo build has started: Quote Link to comment Share on other sites More sharing options...
V8KILR Posted June 14, 2014 Author Share Posted June 14, 2014 Some more pics: Quote Link to comment Share on other sites More sharing options...
jagman Posted June 14, 2014 Share Posted June 14, 2014 I can see issues with your diagram of proposed set up , and for simplicity you can replace #4 wastegate with a check valve Quote Link to comment Share on other sites More sharing options...
V8KILR Posted June 14, 2014 Author Share Posted June 14, 2014 I can see issues with your diagram of proposed set up , and for simplicity you can replace #4 wastegate with a check valve 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? Quote Link to comment Share on other sites More sharing options...
V8KILR Posted June 14, 2014 Author Share Posted June 14, 2014 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. Quote Link to comment Share on other sites More sharing options...
JasonR24 Posted June 14, 2014 Share Posted June 14, 2014 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. Haven't seen this for a while and its looks quality! Get lots of pictures up of this! I think this is a great idea. Quote Link to comment Share on other sites More sharing options...
V8KILR Posted June 14, 2014 Author Share Posted June 14, 2014 Haven't seen this for a while and its looks quality! Get lots of pictures up of this! I think this is a great idea. 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. Quote Link to comment Share on other sites More sharing options...
V8KILR Posted June 16, 2014 Author Share Posted June 16, 2014 And here's another pic of the setup before the #1 wastegate pipe was welded on. The #1 wastegate is a Turbosmart 60mm. Quote Link to comment Share on other sites More sharing options...
V8KILR Posted June 17, 2014 Author Share Posted June 17, 2014 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. Quote Link to comment Share on other sites More sharing options...
mellonman Posted June 17, 2014 Share Posted June 17, 2014 The build quallity on this looks amazing, I looking forward to the results , do you have a mapping date planned ? Quote Link to comment Share on other sites More sharing options...
V8KILR Posted June 17, 2014 Author Share Posted June 17, 2014 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. Quote Link to comment Share on other sites More sharing options...
Shane Posted June 17, 2014 Share Posted June 17, 2014 Great to see different things being tried. Looks great. Quote Link to comment Share on other sites More sharing options...
jagman Posted June 17, 2014 Share Posted June 17, 2014 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? First is the spooling of both turbos , as you know the second turbo takes a second bite of the gasses so it's cooler and has less pressure . The pressure in the join between turbos raises with the no2 wastegate closed ,so the pressure differential across the first turbo drops If this happens before the no1 has full spool , it will dramatically slow its turbine . - the faster the no1 is running the more inertia it has to maintain its speed . The second turbo tends to spool faster as it's compressor is off load until it's output is joined with the first turbo , so this aids the no 1 turbo , as the diff pressure increases . None of this is linear and takes time to happen and will get to equilibrium , but at some point the outputs of 1/2 are joined , both compressors are loaded , the no1 will take the lions share as it's turbine has first shot at the hotter gasses , the no2 will run slower but this again alters the pressure in the join pipe , so the turbos will eventually equalise - this takes time . Part throttle will move the the loads /spool and boost and everything is re timed This all needs control and it's complex , getting balance will be a challenge . Quote Link to comment Share on other sites More sharing options...
V8KILR Posted June 17, 2014 Author Share Posted June 17, 2014 First is the spooling of both turbos , as you know the second turbo takes a second bite of the gasses so it's cooler and has less pressure . The pressure in the join between turbos raises with the no2 wastegate closed ,so the pressure differential across the first turbo drops If this happens before the no1 has full spool , it will dramatically slow its turbine . - the faster the no1 is running the more inertia it has to maintain its speed . The second turbo tends to spool faster as it's compressor is off load until it's output is joined with the first turbo , so this aids the no 1 turbo , as the diff pressure increases . None of this is linear and takes time to happen and will get to equilibrium , but at some point the outputs of 1/2 are joined , both compressors are loaded , the no1 will take the lions share as it's turbine has first shot at the hotter gasses , the no2 will run slower but this again alters the pressure in the join pipe , so the turbos will eventually equalise - this takes time . Part throttle will move the the loads /spool and boost and everything is re timed This all needs control and it's complex , getting balance will be a challenge . 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. Quote Link to comment Share on other sites More sharing options...
jagman Posted June 17, 2014 Share Posted June 17, 2014 Il take a read of the link later , your set up is not compound , the second turbo won't feed the inlet of the first turbo as a sole air source , I it's really a parallel supply , this is harder to achieve without surging the compressors . Maybe a true compound is the way to go - you are halfway there Quote Link to comment Share on other sites More sharing options...
V8KILR Posted June 17, 2014 Author Share Posted June 17, 2014 Il take a read of the link later , your set up is not compound , the second turbo won't feed the inlet of the first turbo as a sole air source , I it's really a parallel supply , this is harder to achieve without surging the compressors . Maybe a true compound is the way to go - you are halfway there 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. Quote Link to comment Share on other sites More sharing options...
jagman Posted June 19, 2014 Share Posted June 19, 2014 "I've been thinking of doing a sequential turbo setup for a while now as a means of getting more boost at lower rpm" From your first post , I can't see how you achieve this from your set up without compounding the compressors , in fact you would get the opposite , you have large turbines/ compressors , no extra exhaust gas (only using the residual gas post no1 turbo ) increased exhaust back pressure and restriction . If you compound the compressors or use a supercharger to compound the compressors then yes you can get very high boost /rpm - this is only useful if the engine can flow the extra air at its lower rpm Quote Link to comment Share on other sites More sharing options...
V8KILR Posted June 19, 2014 Author Share Posted June 19, 2014 (edited) "I've been thinking of doing a sequential turbo setup for a while now as a means of getting more boost at lower rpm" From your first post , I can't see how you achieve this from your set up without compounding the compressors , in fact you would get the opposite , you have large turbines/ compressors , no extra exhaust gas (only using the residual gas post no1 turbo ) increased exhaust back pressure and restriction . If you compound the compressors or use a supercharger to compound the compressors then yes you can get very high boost /rpm - this is only useful if the engine can flow the extra air at its lower rpm 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. Edited June 19, 2014 by V8KILR (see edit history) Quote Link to comment Share on other sites More sharing options...
V8KILR Posted June 21, 2014 Author Share Posted June 21, 2014 Getting close now. Should be finished mid next week. Quote Link to comment Share on other sites More sharing options...
JasonR24 Posted June 21, 2014 Share Posted June 21, 2014 Getting close now. Should be finished mid next week. http://mkiv.supras.org.nz/images/articles/seq43.jpg Really looking forward to seeing how this gets on. Any pictures of both turbos in place? Quote Link to comment Share on other sites More sharing options...
V8KILR Posted June 21, 2014 Author Share Posted June 21, 2014 Really looking forward to seeing how this gets on. Any pictures of both turbos in place? Yes there is, but I want to wait until its all finished before I post pics of the whole engine bay. Quote Link to comment Share on other sites More sharing options...
JasonR24 Posted June 21, 2014 Share Posted June 21, 2014 Yes there is, but I want to wait until its all finished before I post pics of the whole engine bay. Oh you little tease Quote Link to comment Share on other sites More sharing options...
V8KILR Posted June 24, 2014 Author Share Posted June 24, 2014 Inter-cooler plumbing and controlling wastegates all plumbed up. Quote Link to comment Share on other sites More sharing options...
Shane Posted June 24, 2014 Share Posted June 24, 2014 Looking good, getting a bit tight in there now. Quote Link to comment Share on other sites More sharing options...
V8KILR Posted June 24, 2014 Author Share Posted June 24, 2014 Looking good, getting a bit tight in there now. Sure is. My fabricator is doing a very good job squeezing it all in there. Quote Link to comment Share on other sites More sharing options...
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