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Probably enough then lol. Sorry if Brettus already posted it here. I have read through the whole thread but there so much here that some of it doesn't stick
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.
Anti-Lag System...... basically injecting fuel into exhaust manifold to keep the turbo spooled
yup, ALS makes the inlet charge richer and retards the timing to make the inlet charge combust closer to the exhaust valve/port opening, resulting in combustion inside the exhaust manifold which instantly spools the turbo. You can set it up however you want it, from mild (road) to exhaust & turbo destroying aggressive (rally/race). The good side is, flames & instant full on boost at any rpm. what's not to like?
You are running t4 twinscroll right? Not sure if they have a smaller A/R available for the footprint
What I think is happening is that when the two exhaust ports open , the initial pulse energy is almost halved because the siamese doesn't go anywhere . It is reducing the kinetic energy available to spool up the turbine .
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.
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)....
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
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
.
Agreed . Need to first establish that the wastegate will flow enough at 16-18 psi . If it's already choked it's going to be worse with the smaller housing.
Originally Posted by TeamRX8
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
.
Yes . Hopefully I will unearth some advantages over and above that though!
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.
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.
That was my very first thought also so I've done a few checks to satisfy myself that it isn't.
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.
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.
Already done .... Already tested it in conventional setup and happy it's as good as it gets . The slow spool is a good indicator that opening valve at cruise is a good thing . IMO
Please don't think I can't work out which way a check valve goes ....................
Don't mess with setting it up to open at cruise yet.
Just set it up like a conventional setup for now.
.
Returned it to a conventional setup .......... that system caused spoolup to be a lot worse. The EBC doesn't switch the valve over till it reaches 1psi ............. with the WG fully open it was struggling to make 1 psi.
07-29-2015, 09:25 AM
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