Thursday, April 10, 2014 - 02:11 pm, by: Robert Day(Lexsmaz)
Looks like a great thing Kurt, the only thing I was wondering is if the Exhaust housing on the Small turbo is going to be a restriction for Exhaust flow to support the bigger turbo at High RPM & higher boost requirements, I suppose if you are only aiming for 11-12 psi total it might not be an issue ??? ..
Thursday, April 10, 2014 - 02:49 pm, by: Kurt Atzmuller(Kurt)
It flows through the small turbo housing and that 45mm gate so between both they should flow well enough. That gate needs to be plumbed back into the feed for the big turbo yet.
Thursday, April 10, 2014 - 05:44 pm, by: Walter Gillmore(Cl33pa)
You have given me an erection... no homo.
10psi from small turbo before wastegate opens and allows all of the exhaust to go to larger turbo. Larger turbo will determine final boost. But with compound its simple addition. 10+10=20psi. Will be good to know how early that smaller turbo comes on boost.
Rolling start and punching it. You will really feel the benefits of the compound setup.
Thursday, April 10, 2014 - 06:53 pm, by: Kurt Atzmuller(Kurt)
I'm not real sure i enjoy having that effect on you Walter... lol otherwise yes i'm fairly happy the way this is coming along. Can play with boost levels on both turbos so don't want to much boost from the small turbo it should make plenty down low on that psi level.
Friday, April 11, 2014 - 09:22 pm, by: Daniel Clarke(Dieseltrain)
Isn't it 10psi on small turbo means 10psi between comp outlet of small turbo & comp inlet of larger turbo ? And then 10psi of actual boost from larger turbo outlet to throttlebody !
Saturday, April 12, 2014 - 10:47 am, by: Ali Saeed(Ali)
Well if you go dual intakes and dual entries into the intercooler, couldnt you call it a sequential compound, and essentially have less restriction on the compressor output side of the bigger turbo?
Saturday, April 12, 2014 - 11:16 am, by: Kurt Atzmuller(Kurt)
One of the main reasons you draw through the large turbo with the small turbo is because this helps the larger turbo spool up 1500-2000rpm earlier in the rev range than it normally would. I'm not sure how it would work really running an intake to both turbo's but the large turbo may spool at 5500-6000rpm instead of around 4000rpm ish.
Saturday, April 12, 2014 - 12:58 pm, by: Ali Saeed(Ali)
Ack I just realised that a sequential setup would require the manifold to feed both turbos, and to make it a compound setup the dump of the small turbo feeds the small one. Cant be done on your setup now!
Saturday, April 12, 2014 - 04:10 pm, by: Walter Gillmore(Cl33pa)
Sequential setup would require a form of bypass valve similar to what is required for twin charging. As without feeding to smaller turbo. The larger turbo would end up pushing the charge of the smaller turbo back into it. And creating a buttload of heat doing so. Also both turbos would need to get to 20psi instead of compounding 10+10=20
Saturday, April 12, 2014 - 04:15 pm, by: Kurt Atzmuller(Kurt)
Don't think it would work to well reversed. You would have the large compressor housing trying to draw air through the small turbo's comp housing. If i'm thinking the right way about it that is! I really wanted to have my setup a lot neater and compact than that one pictured.
I've got the water and oil lines done on the front turbo just need to do a few more bits before i can get to the big turbos oil and water.
Saturday, April 12, 2014 - 05:25 pm, by: Sebastian Grant(Saabg)
Either way the air is having to pass through the small turbo so I would have thought you'd want the cool air from the intake travelling through there rather than the hot from the large turbo.
Saturday, April 12, 2014 - 05:48 pm, by: Blake Gloyn(Blakenz)
the compound turbo set up is well proven, has been around for probably two decades(on racing trucks), and as far as i can see Kurt is getting it right. The reason very few people do them in cars is cost and complexity of engineering a lot of stuff in a small area. Boostlogic in USA do a bolt on kit for the 2jz supra. Price? $6000 US last time i checked.
Saturday, April 12, 2014 - 06:50 pm, by: Kurt Atzmuller(Kurt)
So would it be easier to boost through the small compressor housing or draw air through the small housing? That is the question! I say boosting through would be far better.
Saturday, April 12, 2014 - 09:08 pm, by: Robert Day(Lexsmaz)
Hi Kurt, are you going to be running the intake plumbing the same as the above photo ??
As if you are going that way surely it would work better if you ran separate intakes & filters for each turbo & blend the compressor outlet pipes with as has been mentioned with a by pass valve or similar between the pipes as I think the intake temp's would go crazy with the above plumbing once the big turbo kicked in & started working hard as the air is being basically compressed twice & with the smaller compressor housing of the small turbo it might then also start to restrict the overall air flow output ?? & also could the turbine speed of the small Turbo be maxed out as there is no by pass valve etc to dump off excess air flow from the Big turbo ..
I read that you mention with the above photo shot it helps the Big turbo spool quicker but as the Big turbo has the exhaust outlet from the small turbo constantly plumbed up surely that works better at increasing the turbine speed than drawing air through the compressor side of the big turbo ..
Or if you left the plumbing like above & had a dump / by pass valve in the intake pipe between the turbo's which then directed compressed air from the Big turbo straight into the intercooler pipe by-passing the small turbo once a certain pressure has been reached ..
Saturday, April 12, 2014 - 09:59 pm, by: Walter Gillmore(Cl33pa)
Cmon guys. Compounding the correct way. As kurt is doing. Has been done on engines for years. Mostly diesels. Pretty sure all combos have been tried by others before. This is how it works.