Is there any reason to believe the center housing gets hotter than the other two?

Or
*the gas is more turbulent in on than the other.

Yeah I think having only half the time directly exposed to flowing hot exhaust gasses will make a big difference. 6ms may not seem like a lot of time, but remember the exhaust pulses are short too. It's not just the temperature it's the flow too, you can put your hand in a 500deg oven for a while and not get burned, but if you have a heat gun blowing 500deg air at your hand it will burn quick.

Turn the engine off and see how long it takes for the pipe to stop glowing red .... , a LOT longer than 0.006 seconds !
Do you really think there can possibly be LESS energy in the tube glowing red than the one that isn't ?

I guess it could be slightly hotter .......

It could be for several reasons. The center port could have more flow in total, or it could just be more turbulent flow, or it could have more total contact time.

I think it has more to do with contact time. A cooler sustained torch flame for example will heat metal much faster than a hotter flame which is only on the metal half the time. Even at higher flow rates the exhaust temperature isn't any hotter, it just has a bit more turbulence from the higher flow. 6ms doesn't seem like a lot of time, but that's per revolution, if you think about it like a percentage it makes a lot more sense.

But ................... 6ms pulsing is practically constant flow for what we are talking about.

Anyway .... suffice it to say that the center tube already flows a good % of the total flow in an NA engine.... I hope it's enough for what I'm trying to do!
It will be interesting to see if I manage to take this to the point where the siamese creates too much backpressure and causes boost creep as that would give us some good info on what is possible.
The ability to fully open the WG via that plumbing/light spring as you suggested will be a major help to that end i'm sure .

It might be an efficiency issue WRT emisssions/clean burn but in terms of what comes out of the port ........... can't see why it shouldn't spool up the turbo like a mofo!

I'm hoping the fact that there wont be much backpressure after the port will help in that regard.

I hear what you're saying. I only have doubts and am not sure either way. Tried my best to present it that way.

That's how I read it too .
I was going to wait till it was done but thought it might be worthwhile discussing first ... in case there was something I had missed that meant it was a waste of time and money. Thanks for the input .

Awesome project, good luck with it. ETA on the initial tuning run?
If the Siamese WG setup doesn't quite pan out you could probably install an additional pair of WGs pre-turbine (1 each port) and still realise the same performance goals you're shooting for. Would be a bitch to dial them in with the Siamese WG to get best efficiency.

Can you detail any port work you might be doing on the rebuild and expected gain from the work? Tempted by the PPRE Bridgeport?

Thanks James.
Just rang them and it's gunna be a couple of weeks away before we start :( . Shouldn't take more than a week to get all the fab work done ... then the fun starts.

Doubt I will do much porting work on the rebuild ... maybe a polish of the runners . As far as the PPRE bridgeport goes - not something I would incorporate into a turbo build . BTW I might be doing the tune for that soon :)

Look forward to seeing the progress and the end result.

Hope it works!!! Good luck.

Brettus, I worry about the large amount of heat the waste gate will see. If you plan on having the WG open as often as you are saying its going to get very hot. A traditional WG has an internal baffle made of silicone/nomex or some crap like that. You would be well past most WG's heat threshold. Synapse engineering makes a baffless WG in both 50 and 40mm. Another option would be a water cooled WG such as the offerings by TiAL.

I think the only concern will be at WOT and high rpms . It is something i'm wary of and the WG i have can have water fitted (Tial) .

The way I'm looking at mounting it , there wont be any pipes near the WG body plus it will get a lot of fresh air over it . I'm sure that will help .

sounds good. Why not take advantage of the the ability to use a dual spool turbine housing? It would help a good amount on such a large turbine. Any info or thoughts yet on your target piping and routing/sizing? As Team had mentioned this is a great opportunity to do some innovative work. I'm really looking forward to seeing things progress.

I will be ............. ?


I have the routing sorted , but just picked up some SS heavy wall bends from the fabricator ...... Looks like I'll have to use 35 ID as the 42ID alternative is just too big !

I guess I did not glean that info from the prior posts. Cool!

I had meant the intake/IC piping setup plan.

oh ok ... think i will replace the stock greddy pipe from maf to turbo ... 70mm OD probably . The the turbo outlet could be a mission .... 21/4" looks as big as i can get there .

35mm ID??? Seems counter-productive to your goal ...

yeah ... been researching this ....http://www.rx7club.com/single-turbo-...l-flow-978453/

Older series setups go as low as 35mm ID and the ideal (spool vs peak power) is considered to be around 44mm ID .
BUT :
3x 35mm > 2x 44mm (2880 vs 2770mm2)

I also read that going larger than the turbo entry area was pointless ....... 35mm is only marginally smaller than the T3 divided flange size.

So it should be great for spoolup but I don't think it will be a penalty on the top end for my target whp.

AND ..... it will fit . the 42ID option wont.

I was mostly concerned about the long pipe from the outer front rotor port. The 13B has a straight-thru peri port and much higher energy per pulse as a result.

Would you see any benefit from making equal length runners .... or would that be counter productive ?

Pipe flow restriction is diameter x length relationship. If there isn't room for 42mm ID then it doesn't seem like there's room to make it equal length. Shorter is better IMO. Given the space you're only solution would be to make the rear port pipe longer.

But 35mm ID is close to the area of the smaller center port. So essentially the end ports are choking down to the center port size. At low rpm spooling up that should be good, but then may be too restrictive at high rpm/boost. Your power goal requires a lot of mass flow.

Yeah , the only way for equal length is to make the rear pipe longer by about 250mm .

I think the SS heavy wall is actually more like 36ID (don't actually have a sample ATM)

so:
36.7mm pipe = 1058 (edit)
front and rear ports = 1080
centre port = 810
Turbo entry = 1130

It shouldn't be much of a restriction ... given that they don't have to flow any WG gases .

1.25" Std/Sch 40 pipe is 35mm ID, 42.2mm OD

Typically 1.50" Sch. 40 pipe is considered minimum ID for shared turbo/wastegate flow. It will come down to which one is more restricted; wastegate or turbo feed