I would have thought a bit more fuel in the ramp up section would cause it to still be burning when the exhaust valve opens and therefore expanding in the exhaust manifold. But that's just a preliminary thought since you brought it up. I'll have a cup of coffee and think about it.
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Originally Posted by 18psi
(Post 1280385)
...I'm not really impressed with how late that thing comes on though, that's for sure.
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Yep, that too. It falls off really hard up top, so it's lose/lose
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Originally Posted by 1993z32
(Post 1280662)
I'm actually a little surprised at the top end, 15psi on a turbo that big with a 1.8L and makes the same torque as my 2554R/stock 1.6L/Begi mani/2.5" exh/13psi from 6000 to redline? I am on E85 but I figured the GTX with a 3" exhaust would be flowing a lot more efficiently than a 2554 in the high revs. :dunno:
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I dont think begi made the s4/s6 for the 1.6
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Originally Posted by sixshooter
(Post 1280631)
I would have thought a bit more fuel in the ramp up section would cause it to still be burning when the exhaust valve opens and therefore expanding in the exhaust manifold. But that's just a preliminary thought since you brought it up. I'll have a cup of coffee and think about it.
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Originally Posted by patsmx5
(Post 1280529)
On my GT3271, I found a lot of spoolage by not running pig rich while it spools. I ran it around 14:1 at 100kPa, 13:1 at 140kPa, etc, tapering to target AFRs when you get to target. That made a very very nice improvement in both driveability and spool. Worth a shot since your posted AFR target table is richer than needed at very low boost.
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Originally Posted by sixshooter
(Post 1280718)
Log begi mani or tubular?
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which (imo) is still better than the FM in terms of flow, but still lightyears behind proper tubulars
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A year later....did this ever get figured out? Im trying to pick my next turbo but these results aren't helping. It took codrus 24 psi and 100 octane to make 340 on the 63mm billet wheel. I still think the bigger gt2871 may be superior to the billet stuff
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Yeah, threadsurrection, but..
These numbers are far from impressive, Im about to run a Premium Gasoline NB8a setup with a GTX2871 and if it doesnt destroy this setup ill be so mad. Dann |
Even a standard gt2871 should destroy this. A gtx2863 did destroy this. Thats why i asked if it got figured out because something is up
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I haven't changed anything since that dyno run except some reliability mods. The possible restrictions are the FM log mani, the 70 degree bend in the 3in downpipe about 10 inches from the turbine outlet, the 2" hotside intercooler piping, the intercooler, etc. Everyone so far says my timing is good, but pointers are welcome. Is base timing off or maybe a tooth off on a camshaft? I'm not sure.
It's been parked mostly and I've been busy selling a house. But I'd love some ideas. |
Originally Posted by sixshooter
(Post 1358677)
I haven't changed anything since that dyno run except some reliability mods. The possible restrictions are the FM log mani, the 70 degree bend in the 3in downpipe about 10 inches from the turbine outlet, the 2" hotside intercooler piping, the intercooler, etc. Everyone so far says my timing is good, but pointers are welcome. Is base timing off or maybe a tooth off on a camshaft? I'm not sure.
It's been parked mostly and I've been busy selling a house. But I'd love some ideas. 2 inch hotside IC piping shouldn't be a big deal either. Again, FM runs 2 inch and its fine. And the standard size for the turbo outlet is 2 inch Whats your air filter setup? Maybe choking the big azz turbo? Still puzzling tho. Im still thinking this is the turbo for my goals but if i struggle to hit even 300whp ill be mad asf |
7 Attachment(s)
Air filter is of adequate size but is in a poor location. Using NA8 intake manifold and Skunk2 throttle body. 3 inch downpipe is covered in heat shields but I have an old picture from a prior disassembly depicting the sharp turn. It is still many times larger than the turbine outlet so even though it's not ideal I don't know if it could cause a tremendous amount of restriction.
This is the downpipe and manifold (with a different turbo). https://www.miataturbo.net/attachmen...426_113819.jpg This is a good depiction of the difference between the turbine outlet size and the 3in pipe: https://www.miataturbo.net/attachmen...426_132910.jpg Again, the bend in the downpipe (very old pic, many of the surrounding components have been changed or rerouted): https://www.miataturbo.net/attachmen...426_113532.jpg As she sits this morning. Note air filter location far less than ideal. https://www.miataturbo.net/attachmen...906_074552.jpg https://www.miataturbo.net/attachmen...906_074531.jpg |
Originally Posted by sixshooter
(Post 1358677)
I haven't changed anything since that dyno run except some reliability mods. The possible restrictions are the FM log mani, the 70 degree bend in the 3in downpipe about 10 inches from the turbine outlet, the 2" hotside intercooler piping, the intercooler, etc. Everyone so far says my timing is good, but pointers are welcome. Is base timing off or maybe a tooth off on a camshaft? I'm not sure.
It's been parked mostly and I've been busy selling a house. But I'd love some ideas. |
the cheated radius on the downpipe right at the turbine exit doesnt look like it would promote flow very well but who knows. thats not the gtx2867 is it? looks like a small chinese thing
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Originally Posted by LownSlow616
(Post 1358759)
thats not the gtx2867 is it? looks like a small chinese thing
https://www.miataturbo.net/attachmen...906_074531.jpg This was Chinese 2870: https://www.miataturbo.net/attachmen...426_113819.jpg |
Originally Posted by shuiend
(Post 1280389)
I think that is due to the cast manifold. Hustler had some old threads about his 2860 spooling like donkey shit on a begi cast manifold.
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Originally Posted by Girz0r
(Post 1358769)
YUP. :eggplant:
if i had a turbo that big and shiny and was making as much power as ppl with stock engine and gt2560 id lose sleep at night. not even trying to sound like an ass, just trying to pick my next turbo and i cant have this happen to me... |
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