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It seems to me that there are too many generalisations made about what flange/pipe size is ideal without considering how much flow has to go through it.
Firstly the difference between a T3 and T4 turbine housing is only in the size of the entrance to the housing. The rest of the housing, where it necks down to form the volute is identical either way. So IMO, a T4 is only justified when the pipes going to it are too large to get an efficient transition down to a T3. In a high hp 13B , that would always be the case so I guess the point is moot.
Also , when considering size of pipes to the turbine, surely the method of wastegating is relevant as is the turbine size and AR. An internally wastegated turbo must need larger pipes to the turbine than an externally wastegated setup would. A larger turbine must also benefit from larger pipes, as would a turbine with a larger AR.
It seems to me that there are too many generalisations made about what flange/pipe size is ideal without considering how much flow has to go through it.
Firstly the difference between a T3 and T4 turbine housing is only in the size of the entrance to the housing. The rest of the housing, where it necks down to form the volute is identical either way. So IMO, a T4 is only justified when the pipes going to it are too large to get an efficient transition down to a T3. In a high hp 13B , that would always be the case so I guess the point is moot.
Also , when considering size of pipes to the turbine, surely the method of wastegating is relevant as is the turbine size and AR. An internally wastegated turbo must need larger pipes to the turbine than an externally wastegated setup would. A larger turbine must also benefit from larger pipes, as would a turbine with a larger AR.
It seems that the T3 and T4 nomenclature does cause a certain confusion.
I think way back when, T3 and T4 designated certain frame sizes, but now you can get a lot of different turbos of varying frame sizes with whatever mounting flange you want. So then it comes down to packaging, and optimizing flow configuration into the the turbo and wastegate. In my instance, having a 2" id v-band flange makes it necessary to abruptly merge the two exhaust streams at the flange. I'm still not certain just how much restriction this causes, because the .82AR housing is really restrictive. The thought of leaving the manifold as is and upping the AR to 1.05 is very appealing, but would that then reveal the restriction at the manifold merge?
Now that I've really examined the issue, It's clear that the twin scroll configuration has benefits beyond just flow. as outlined in the SAE paper from Mazda about the T2 twin scroll this certainly can't be discounted. But how big is the gain?
If you think of the exhaust as a static flow, then it would be easy to view the merge as a huge restriction. But, the flow from each rotor is pulsed, and as such the velocity through the merge at different times may actually contribute to some scavenging effect. And if that's the case, the gains from going to a twin scroll may be less significant.
This would all be a lot easier if we didn't have to leave the air pump in place for visual inspection. As it is, even the current configuration doesn't have much room to spare. So I'm not even certain I can make a twin scroll T4 fit without losing the air pump. My friend, the owner of the car, seems to leaning more towards T4, so at some point I may be elbows deep in my first turbo manifold build.
I don't think the V-band flange wouldn't be a good candidate.
Huh? I'm referring to converting a T3 to T4 by means of porting. They use the same bolt pattern and material on the turbine housing (and usually manifolds) can account for this without issue. More flow = less backpressure = safer power.
Yeah, but the manifold he has is actually a T2/T25 with 2" ID V-band (rated T3 because it flows as much as standard rectangular open volute T3).
Question is, can two 2" runners merged int 2" V-band support enough flow to warrant switching to 1.05AR housing.
I say, it will be an improvement over the 0.82AR.
However, even more improvement will be had with a manifold/flange more suited to his power goals.
Ideally though one would run 2.5" tapering to 2" runners merging into whatever flange gives you the same area as two 2" diameter pipes. If you can avoid it you dont want to try to merge and increase velocity with smaller diameter in the same short lenght of flange area. Better to increase velocity gradually in runner taper and then turbo volute and merge as cleanly as space allows as well (high angle collector with low turbulence).
But the fab work is undeniably gorgeous and the design elegant. Id be of a mind to just go with whatever your man who is doimg the work has planned and see how it goes.
Just going off my uneducated intuition, it looks like it would be amazing as a low(ish) boost, super fast spooling beast that will still flow up top given the massive wastegat priority.
But the fab work is undeniably gorgeous and the design elegant. Id be of a mind to just go with whatever your man who is doimg the work has planned and see how it goes.
Just going off my uneducated intuition, it looks like it would be amazing as a low(ish) boost, super fast spooling beast that will still flow up top given the massive wastegat priority.
I assume you are talking about the current setup from the photo above. I agree it's beautiful. Very direct energy transfer, compact, as you said, "elegant". But really, the spool is not as quick as you'd expect, and it just won't get much past 400rwhp.
Originally Posted by BLUE TII
Look to what HKS used for their T04Z kit as it is sizwd for the power you want.
I've been searching intently for examples of T4 fitments that would allow for the retention of the air pump, and have recently "discovered" the HKS T04Z setup you posted. It looks to me like this is "proof of concept". The T04Z is a similarly sized turbo to the PT6266, and it looks to fit in the required space. I think the wastegate priority looks less than optimal and doesn't really provide for the isolation of the exhaust pulses for the true twin scroll effect.
I think a shorty T4 manifold like this that implements a wastegate design similar to what Howard Coleman uses on his setup may do the trick. But the proof would be in the pudding.
the HKS V band is for the T51, which actually did fit with the airpump, and was even CARB legal.
the HKS To4S manifold is the cast divided one, and it also for sure fits with the air pump.
the HKS To4Z manifold is the flanges stainless, and the kit doesn't use the air pump, but its probably really close. Manifold is short, because short is better
Above is the FD T04Z manifold I used on my FC when I switched to the EFR 7670 turbo. I modified it for the two 45mm wastegates and changed the WG inlet angle for higher priority. Issue I then had was that when the wastegates were cracked open the flow and pressure of the exhaust would push them open further in the high rpm and boost would drop.
Woyld have had to plumb boost to the top of the actuators to get the boost flat. Interestingly, when I pulled the WG line off the actuators altogether the exhaust pressure alone wasnt high enough to push crack the wastegates open.
I believe the HKS T04Z came with 3 different stainless manifolds over time.
Divided T04 with square flange wastegate, divided T04 with V- band wastegate and V-band T04Z with V-band wastegate. I have seen posted pictures of all three from members who have the T04Z kit.
Above is the FD T04Z manifold I used on my FC when I switched to the EFR 7670 turbo. I modified it for the two 45mm wastegates and changed the WG inlet angle for higher priority. Issue I then had was that when the wastegates were cracked open the flow and pressure of the exhaust would push them open further in the high rpm and boost would drop.
Woyld have had to plumb boost to the top of the actuators to get the boost flat. Interestingly, when I pulled the WG line off the actuators altogether the exhaust pressure alone wasnt high enough to push crack the wastegates open.
Thinking in terms of static pressure, it's easy to simplify the dynamics of an exhaust stream in our mind. But we need to realize how much kinetic energy is involved. The static pressure was acting on the surface of the wastegate valve only until the valve opened and the exhaust started moving. Then the even greater kinetic energy of that high velocity flow took over and the spring couldn't overcome it.
Exactly, wastegate placement/priority is a highly dynamic situation. Different set-ups will want different variations of WG size, position and priority to reach their goals.
As I learned coming from a set-up with same size turbo as the efr 7670 with a single 60mm single wastegate where could not fix boost creep until I ported the manifold and turbo bigger to reduce exhaust velocity. Then I kind of overshot on WG priority on the EFR because I was so afraid of boost creep.
So, Turblown has pictures of a T4 IWG turbo mounted to an engine with the air pump on it. Their "shorty" manifold moves the Turbo farther forward, but it still has clearance.
Now I have reasonable confidence that this configuration is doable.
The attention now turns to the wastegate.
Typically with a twinscroll setup, a dual wastegate setup is used. However I’m thinking of going with a single wastegate that has a divider all the way to the valve.
I found posts by Blue TII that highlight his attempt at this arrangement. He used a modified turbine housing that had a IWG, and converted it to EWG. This was a very forward thinking project. Unfortunately there were problems with the divider. I think this was more due to his unique configuration. I have seen a couple instances of this configuration with tubular style manifolds, with only one other reported failure (that I found), and I think that manifold did not look like it was constructed well.
Then it comes down to, what size? I see that Howard Coleman is using a 60mm gate. But his manifold, by his own description, is not designed with wastegate flow as a priority.
The wastegate we are currently using is a 46mm Precision Turbo unit. It has controlled boost well, except when the set screws came out that hold the valve stem to the diaphragm. Because the divider splits the area in half, even more when you account for the area of the divider itself, I was concerned it might need to be bigger. But when I draw up the opening and measure the area, each of the sides are about 43% the area of one side of the divided T4 flange. The EFR internal wastegate looks small comparatively. As long as I make a good flow path, I think the 46mm will do the job.
it depends on the flow of the engine, and flow of the turbo, and the boost you want to run, and then manifold design is a factor too..
for instance a stock FD has a perfectly adequate wastegate, but when you add flow (full exhaust), and try to keep boost the same, suddenly the wastegate isn't adequate, and needs to be bigger. however if you wanted to run higher boost (.6 to .8) then the wastegate is fine again.
Huh? I'm referring to converting a T3 to T4 by means of porting. They use the same bolt pattern and material on the turbine housing (and usually manifolds) can account for this without issue.
That turbine is still a T4 , T3 has a different bolt pattern to that. However , for some reason B/W don't port some turbine housings out to the full T4 opening sizes and leave the end user to do it for themselves.
Found this note on one resellers website :
Even though these housings have a T4 flange patter, the volutes are T3 sized. We can port match the volute to match the standard T4 volute for an additional charge.
That's my exact point. You can CONVERT a T3 Turbine Housing (as pictured in what I posted) to a T4. You also quoted my text written on Full-Race Motorsports. Awesome.
That's my exact point. You can CONVERT a T3 Turbine Housing (as pictured in what I posted) to a T4. You also quoted my text written on Full-Race Motorsports. Awesome.
Ok ..gotya ... It's just that , the way I read your first post made it sound like T3 and T4 have the same bolt pattern ...which they don't.
the data point is the last prior to a TPS downtick. as you can see i am at 20 psi and my EMP/EMAP is 24.9 at 6457 rpm with my EFR 9180. up to 5687 i had more boost than backpressure. there are many factors that influence EMP. intake and exhaust ports, turbo manifold (big influence) and hotside system which includes divided or V band (big deal on a 2 rotor rotary), turbine wheel size, configuration, material, hotside housing and exhaust. for many, the hotside housing and turbo selection are easiest to effect.
i did a back to back comparo in 2018 (up to 9000 rpm) using a BW SXE 62 between the .91 and 1.0. i was surprised how little difference there was as the .91 made very good power at 8800! EGT was 60 F lower with the 1.0.
i will probably be buying a G35 1050 after i finish w my 9180 and will look forward to comparing it to my present turbo.
09-23-19, 09:59 AM
