Originally Posted by stinksause
(Post 4708190)
True 4 inch exhaust?
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Exhaust is full 3" .
Full spoolup to 15psi is around 5000rpm . Not teribble , but well short of what I was hoping for . The problem has little to do with the turbo/exhaust and everything to do with the siamese port/pipe volume ,I think. |
ALS is next on the list then? :lol:
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Originally Posted by shambo
(Post 4708226)
ALS is next on the list then? :lol:
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Anti-Lag System...... basically injecting fuel into exhaust manifold to keep the turbo spooled
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wastegate staying fully closed?
the two pipes are also converging a bit sharply at the turbo flange and the Renesis lags the 13B in exhaust gas energy due to the sideport flow angle at least the dedicated mid-port wastegate idea seems to have some merit, but if it's that slow to spool up then I would conclude the wastegate is not being pushed too hard yet if it's actually staying fully closed to that point. The real proof is to swap swap in a tighter turbine housing and see if it can still generate stable boost and better spool without crimping the top end too much. |
Originally Posted by Brettus
(Post 4708216)
The problem has little to do with the turbo/exhaust and everything to do with the siamese port/pipe volume ,I think.
You are running t4 twinscroll right? Not sure if they have a smaller A/R available for the footprint |
Originally Posted by RotaryMachineRx
(Post 4708229)
Anti-Lag System...... basically injecting fuel into exhaust manifold to keep the turbo spooled
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Originally Posted by stinksause
(Post 4708275)
Could you elaborate?
You are running t4 twinscroll right? Not sure if they have a smaller A/R available for the footprint been thinking of some possible remedies : *Porting the end ports as much as possible so they open before the siamese ports. *Filling up the cavity area behind the siamese port sleeve and fully dividing the port which should halve the amount of gas flowing into it. *Replacing turbine housing with the 0.83A/R The good thing about all that is that I was planning to rebuild the engine anyway as compression on this one is way down (which when rectified should also help with spoolup). Existing is a 1.01 T3 twinscoll. |
It's not halved if the wastegate is closed, there will be some loss, but otherwise you are just forcing a large percentage, say 95% as a guess, through the end ports. I wouldn't think that flowing each rotor out only the main end ports would have much kinetic impact at low rpm as far as a restriction goes. All the 3rd port serves is to allow that far corner of the rotor to evacuate for emissions purposes. Mazda did not intend to use it otherwise.
filling and halving center port is easier said than done; even the factory inconel divider fails long term on that port, really soon on most dedicated race engines. My builder requested for me to replace the used center iron with a new one for that reason, which I did. think I would try the .83 housing before doing anything else, even with the weak engine. everything I've seen suggests that porting is all risk and very little gain, not worth doing much more than a minor clean-up which I can't even do that in the current race class structure. That area is seriously heat stressed for FI, removing material will only exacerbate the situation. |
Originally Posted by TeamRX8
(Post 4708297)
It's not halved if the wastegate is closed, there will be some loss, but otherwise you are just forcing a large percentage, say 95% as a guess, through the end ports. I wouldn't think that flowing each rotor out only the main end ports would have much kinetic impact at low rpm as far as a restriction goes. All the 3rd port serves is to allow that far corner of the rotor to evacuate for emissions purposes. Mazda did not intend to use it otherwise.
filling and halving center port is easier said than done; even the factory inconel divider fails long term on that port, really soon on most dedicated race engines. My builder requested for me to replace the used center iron with a new one for that reason, which I did. think I would try the .83 housing before doing anything else, even with the weak engine. everything I've seen suggests that porting is all risk and very little gain, not worth doing much more than a minor clean-up which I can't even do that in the current race class structure. That area is seriously heat stressed for FI, removing material will only exacerbate the situation. Tend to agree re the sleeve . Just going through the possibilities at this stage as I'm sure it would spool a lot better if the siamese was not there to divide the initial pulse energy. |
This excites me though :
Comparison of old setup vs new setup at pretty close to the same boost (rpm vs time).... https://cimg4.ibsrv.net/gimg/www.rx8...3069e5463f.png Virtual dyno is looking good for my goal too... and I haven't even touched the old tune yet . It's running quite rich and timing is very conservative . |
I see where you mean now, Yes, as the rotor comes around the side exhaust ports become exposed there will be a surge pulse that flows into the cavity formed by the center port and pipe to the closed wastegate (and possibly back-flows too). I'd think it would stabilize with rpm, but that may be what you're seeing. Getting the turbo to spool quicker with a tighter turbine housing and then be able to start cracking the wastegate earlier may be beneficial to help offset that
re;Log graph that seems normal given the turbo & turbine size increase. As we've been discussing, it's just a matter which part of the rpm range you want efficiency and desired power level . |
Originally Posted by TeamRX8
(Post 4708317)
Getting the turbo to spool quicker with a tighter turbine housing and then be able to start cracking the wastegate earlier may be beneficial to help offset that
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Originally Posted by TeamRX8
(Post 4708317)
re;Log graph
that seems normal given the turbo & turbine size increase. As we've been discussing, it's just a matter which part of the rpm range you want efficiency and desired power level . |
I think your WG might be leaking by, perhaps a vacuum line/plumbing issue. Also there is no sign of spool on any of the graphs, they look way to straight almost like a SC setup.
When you get a chance it would be nice to see MAF vs RPM and Virtual dyno vs RPM. The graphs posted just don't have enough reference to figure out what's going on. |
Originally Posted by Harlan
(Post 4708354)
I think your WG might be leaking by, perhaps a vacuum line/plumbing issue. Also there is no sign of spool on any of the graphs, they look way to straight almost like a SC setup.
When you get a chance it would be nice to see MAF vs RPM and Virtual dyno vs RPM. The graphs posted just don't have enough reference to figure out what's going on. Will do some charts as you suggest later . Just in the middle of setting up the WG open at cruise per your earlier suggestion . The 4 port valve works extremely well BTW ! Thanks for that . |
Don't mess with setting it up to open at cruise yet.
Just set it up like a conventional setup for now. Check valves and a VAC source will just complicate things right now. And getting the check valves backwards could delay or prevent the WG going full closed. |
Originally Posted by Harlan
(Post 4708359)
Don't mess with setting it up to open at cruise yet.
Just set it up like a conventional setup for now. Check valves and a VAC source will just complicate things right now. And getting the check valves backwards could delay or prevent the WG going full closed. Please don't think I can't work out which way a check valve goes .................... |
Originally Posted by Brettus
(Post 4708361)
Please don't think I can't work out which way a check valve goes ....................
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so wait this setup is already installed in your car, and there are no pictures?!?!?!?!?
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Since we're all piling on, you don't have your MAF map extended past 4.69V?
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Originally Posted by FazdaRX_8
(Post 4708372)
so wait this setup is already installed in your car, and there are no pictures?!?!?!?!?
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Originally Posted by TeamRX8
(Post 4708396)
Since we're all piling on, you don't have your MAF map extended past 4.69V?
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Huh, thought the first log where you said it was maxed out indicated 4.69, my bad then.
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Originally Posted by Harlan
(Post 4708359)
Don't mess with setting it up to open at cruise yet.
Just set it up like a conventional setup for now. . |
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