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ported 90+manifold

This is my 90+, matched to my 16T :

MoteurVolvo056.jpg


MoteurVolvo049.jpg


MoteurVolvo043.jpg
 
Erland Cox said:
The worst thing you can do to that manifold is to port it up to fit a T3 turbine.
The T3 turbine housing should be welded instead and ported to the shape of the manifold.
Never make the manifold larger at the turbine flange.
If you do you might as well us an old 240 manifold.


Erland
Click to expand...

and here's some great advice.
You guys aren't really thinking about it systemically - you want a smooth transition into the volute, which on most t3 flanged turbos, is not going to be any larger than the outlet of the 90+.

It might look great in pictures, but you've effectively dispersed any sort of pulse energy you might have gotten from the updated design by taking the volume right there at the flange area and increased it immensely, only to have it neck right back down to the size of a penny. A large to small taper is great if you're dealing with something that's larger already at the turbo flange (i.e. on a tubular header with a nice collector, you have that taper that starts there, if you can continue that into the volute on the housing it will work nicely).

What op is wanting to do essentially, is create an expansion chamber between the manifold and the turbo. That's all that you're going to gain by hogging out the manifold and a td04hl housing (or any housing really).

The restriction in the system is more the turbo itself, and the turbine housing. no amount of porting at the turbine housing flange is going to have a profound affect on that. While it might look good, and you might could get it to read awesome numbers on a bench (well, just the manifold, not the turbine housing, see above), at best it won't do anything at all, and the downside...well goes down from there.

think about it as a series of pipes or straws.. you start at the cylinder head with let's say a 1.5 inch diameter pipe. it reduces down to .75 over the span of a foot, and there it attaches to another piece of pipe that's .75 which further reduces down to the size of a drinking straw over the course of another foot. What good is it going to do if you take the transition between the two and make it a 3 inch piece of pipe? Think about water flowing through that if you need to visualize it. What good is a 3in x 1in wide piece of pipe going to do between the two .75 flanges?

Further consider the turns involved, and by going into that 3in section the water suddenly doesn't turn as sharply into the other segment, what's the situation going to look like right there? it's going to back up, bounce around, and lose velocity.
 
I'd ditch the 15g conical and go with a flat flanged housing or angled flat flange housing as it's got the biggest output hole. I know you won't be able to then just bolt on your stock downpipe, but the money you saved from not having your 90 plus mani flow checked.....
 
Mikoyan said:
On the risk of threadjacking: Erland, would you care to elaborate a bit on that, while I put away my grinder awaiting your reply :roll:
Click to expand...

A turbo charger can be impulse driven from the blow down pressure pulse and the heat or that can be traded for pressure instead.
The pressure will work in all directions though also up towards the port. As soon as the area in any port is opened up somewhere the velocity will go down and the pressure up. If you look down into the turbine nozzle and see how tiny that is ask yourself what good will an area that much bigger in the flange between the turbo and the manifold do? It will lower the velocity, increase the pressure, lower the strength from the blow down pressure wave and flow, lower the temperature seen by the turbine and increase back pressure. A properly impulse driven manifold has only 3 cylinders connected to one turbine inlet to avoid cross talking between the cylinders but it is possible to run 4 cylinders without much trouble like in this application. Of course a twin entry turbo with the same area from the cylinder head and to the turbine inlet is even better with cylinders 1-4 and 2-3 connected. I have had engines with ported 90+ manifolds with a stock T3 turbine and with unported manifolds together with a welded T3 turbine and there is a huge difference in turbo response time.


Erland
 
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