my miata's back... slower :( AVO beats BEGI
#42
Supporting Vendor
iTrader: (33)
Join Date: Jul 2006
Location: atlanta-ish
Posts: 12,659
Total Cats: 134
remove backpressure
here's their mani w/ a seperate wg, visually replace the flange and external wg for a turbo flange and turbo. might have to do a little trimming, but imo would be worth it
here's their mani w/ a seperate wg, visually replace the flange and external wg for a turbo flange and turbo. might have to do a little trimming, but imo would be worth it
#44
Yes the AVO mounts a lot lower and there's a nearly straight shot from #3 into the turbine (funny the turbo mounts rearward despite lack of space for the downpipe). It also appears that the curves for #1 and #4 are gentler. On the BEGI the runners come out from the ports a bit before turning sharply, to make room for wrenches. On the AVO they begin curving immediately, thus the gentler radius. There is also a slight turn-in into the turbine for #1 and #4... but of course #1 and #4 still "look" into each other.
As for JasonC's dilema, I think that the ETD Manifold is a sharp design and 1.25" schedule 40 is the smart choice for the runners. It will make for a very nice collector. It's too bad that the BEGi apparently does not perform as well as the AVO, but I am not surprised. I do believe that the divider is an improvement over the previous design though and with some creative port work it could even be better.
Mark
#45
Jason - 170kpa at 3000rpm. AVO, MoTeC, GT2560R! http://www.performance5.com/images/d...TeC11.5psi.pdf Interestingly, I also thought the AVO turbine outlet was a bad design, it looked very restrictive. May be the back end doesn't make that much difference......
Phil
#46
I may have to take back what I said about the topend being weak.
The torque seems to flag off less going from 5500 to 7000 rpm with the BEGI than the AVO. It may actually make more power at 6500 rpm or so. This may be due to the downpipe. I agree the AVO turbine discharge looks restrictive.
Phil -
FM vs BEGI - The BEGI design almost looks like there's a plenum before the turbine inlet, as opposed to the FM mani (which you described).
I've seen 1 other AVO+GT2560 plot that shows the same incredible spoolup as your plot. It seems the AVO+GT2554 has the advantage below 2700 rpm or so, and perhaps response in the 3000-3500 rpm range.
The torque seems to flag off less going from 5500 to 7000 rpm with the BEGI than the AVO. It may actually make more power at 6500 rpm or so. This may be due to the downpipe. I agree the AVO turbine discharge looks restrictive.
Phil -
FM vs BEGI - The BEGI design almost looks like there's a plenum before the turbine inlet, as opposed to the FM mani (which you described).
I've seen 1 other AVO+GT2560 plot that shows the same incredible spoolup as your plot. It seems the AVO+GT2554 has the advantage below 2700 rpm or so, and perhaps response in the 3000-3500 rpm range.
Last edited by JasonC SBB; 07-05-2007 at 06:24 PM.
#47
That's why my BEGi manifold is separated all the way to the turbine inlet (which is a divided inlet.) I rather think that forming a plenum may be detrimental, I would have extended it further and flowed it to find the best terminal shape.
It is possible that once the gases have sufficient velocity it may be that the BEGi makes up for some of it's deficits. I am looking forward to comparing it with the Ebay tubular manifold that I was using, which really was not a bad unit in concept.
Mark
It is possible that once the gases have sufficient velocity it may be that the BEGi makes up for some of it's deficits. I am looking forward to comparing it with the Ebay tubular manifold that I was using, which really was not a bad unit in concept.
Mark
#51
In lieu of measuring my cylinder head's ports I looke at the matching ports on my AVO manifold which closely matched the cylinder head. The holes are an oval, 1.25" x 2.0" across. As near as I can tell, the circumference would be close to that of a 1.75" pipe. IOW if you bash or shape a 1.75" pipe you can make it match the ports. It seems to me that a 1.25" pipe will be too narrow to match the ports. Comments?
#52
2 Props,3 Dildos,& 1 Cat
iTrader: (8)
Join Date: Jun 2005
Location: Fake Virginia
Posts: 19,338
Total Cats: 573
flow area should be kept constant. remember when you smoosh a pipe to be a 1.25 x 2 oval your flow area becomes [pi*(1.25^2)/4 + .75*1.25] or 2.16sqin which is closer to the flow area of a 1.65" ID pipe.
You'd probably be ok decreasing diameter as long as the oval-round transition is smooth and long enough to prevent turbulence.
You'd probably be ok decreasing diameter as long as the oval-round transition is smooth and long enough to prevent turbulence.
#54
2 Props,3 Dildos,& 1 Cat
iTrader: (8)
Join Date: Jun 2005
Location: Fake Virginia
Posts: 19,338
Total Cats: 573
that was the area of an oval with straight sides... area of 1/2 circle plus half circle = area of circle (pi R squared or pi D squared over 4) plus area of rectangle between halves. D x (W-D). though maybe my math is wrong.
What's ETD use by default?
What's ETD use by default?
#60
re: 1.25" vs 1.5" piping.
y8s points out that the real i.d. of 1.25" schedule 40 piping is 1.38", 1.5" is more like 1.6".
That out of the way ...
Just got off the phone from ETD. They said
a) 1.5" piping is way more difficult to merge at the collector for a T25 flange. They use 1.5" for T3 flanges
b) They expand the 1.25" pipe at the exhaust ports as much as they can to match up with the ports
Now I wish there were a not-overpriced ball-bearing T3 turbo sized between a GT2554 and a GT2560.
y8s points out that the real i.d. of 1.25" schedule 40 piping is 1.38", 1.5" is more like 1.6".
That out of the way ...
Just got off the phone from ETD. They said
a) 1.5" piping is way more difficult to merge at the collector for a T25 flange. They use 1.5" for T3 flanges
b) They expand the 1.25" pipe at the exhaust ports as much as they can to match up with the ports
Now I wish there were a not-overpriced ball-bearing T3 turbo sized between a GT2554 and a GT2560.