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imo a divided housing can offer close to the same advantage over an undivided housing on the 3-port Renesis exhaust, but as you stated; just not with the manifold as configured here.
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As you know , I've tried a couple of designs with a twin scroll housing. The best I could do was around 150rpm better spoolup ...not really worth it.
Would be interested how you would configure a twin scroll to do better?
First test drive with the G30-660 0.83 . Initial thoughts
*Today is a good 13-14C warmer than the day I did the 3582 log so results for the 30-660 are handicapped by that somewhat.
*Yes it's faster spooling than the 3582 0.82 but not the big difference I was expecting
*From a roll in 3rd we get 10psi by 3000rpm which is only 150rpm improvement on the 3582
*But .......... the slope of the maf curve is a lot steeper (the comparison log on 3582 I hit wot a lot earlier) so I'm expecting 15-16psi by 3400ish which would be 250rpm improvement.
*At same boost level and a hotter day it is making more power than the 3582 as we can see below .... suspect lower emap is the key to that . Will do an emap log later.
*transient response from 4000 and above is exceptional !
Virtual dyno at 9.5psi ..... G30 green line 3582 red line .
Emap log at 9.5psi taken with g30-660 0.83
need to check boost at high rpm because VD shows an extra 25whp over the 3582 (maf is higher also).Blue line at 8000 (no boost cut)
3582@9psi blue line at boost cut 7700
All pointing to better emap (around 1 psi ) from the g30 over the 3582 at similar boost levels
same compressor and if the Garrett turbine map is accurate, the G25 0.92 has a slightly higher flow capacity than the 0.83 G30 housing for the full curve
The elbow is actually 2" to 21/4" then 21/4" through past the steering column then 21/2" to IC . Without the steering column there you can probably clock the turbo to have the exit vertical and go straight to 21/2".
You should take a good look at that word and stop splitting hairs.
not even remotely sure what you mean by that; the G25 0.92 turbine is indicating slightly more flow capacity in the applicable Pr range than the G30 0.83 turbine according to Garrett's own information as indicated below. Still quite a bit lower than the G30 1.01 AR you previously were using.
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it's just a friendly conversation, but if you feel like my word choice is off-base then please suggest your own words that may better describe the situation.
if anything the data suggests lower emap for the G25 0.92 than the G30- 0.83, but to be fair some people still question the flow capacity of the G25's smaller turbine under real world conditions. Yet the smaller impellers in theory should have faster spool to offset the PR differences indicated above. On the one 13B-REW with G25-660 0.92 IWG build you mentioned, I still say the v-band on these is not a good match for a 2 rotor wankel engine, evident by the merge on his manifold and also the change on your own to the T3 flange, and it also has a cat converter of unknown flow capacity. Most people are too cheap to buy a proper cat converter. The HJS converters I ran on my NA Renesis are likely much better flowing than what anyone uses over on RX7Club with an FI engine.
The G25 0.92 is readily available in an open T3 EWG, so it should be a straight bolt on to your manifold and easy to get real world numbers, even if by someone else. What the heck, just put my name on the list and let me know when you need payment.
of course I'd still want it in a divided T4 configuration for my own purposes, which unfortunately they dropped it off the availability chart again with no indication when or if it will ever be offered.
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it's just a friendly conversation, but if you feel like my word choice is off-base then please feel free to offer the words you feel better describe the situation.
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You know we have already had this argument before about the "slightly" higher flow of the 25!
I really have to question your motives here . Because it seems you are really clutching at straws trying to one-up me on tiny little details. Do you truly believe it's worth bringing this up over and over again?
No, it has nothing to do with any of that. Nor can I recall those exact specifics, but then it's not a personal subject for me, nor is it intended as one against you.
At the risk of being considered insensitive; I'm not going to apologize for commenting on a public forum. Mostly because I don't see it as being off topic and it's not directed against you or intended as such. If anything, it seems that an alternative turbo selection may highlight the effectiveness of your manifold even more. Because again, it's the same compressor housing with two turbine size alternatives, both of which are available in a T3 EWG configuration and should be interchangeable on this manifold.
It's just as much on topic as when I suggested using the 0.83 AR housing back in the beginning of this thread almost a year ago. Which was and still is all part of the same inter-related G25/G30-660 discussion in my mind. So in further response; no, there's neither an argument nor straw grasping. If it's anything, it's just a disagreement, if even that; certainly nothing more and certainly nothing less as far as my intentions go.
However, if you don't want to discuss it; then don't, but don't blame me for responding back to your replies on it. I honestly thought your reply was sincere and I'm replying sincerely. I otherwise have no desire in being your enemy or nemesis, but only have control over my own thoughts and feelings.
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Ok .... that's fine . Maybe I'm misreading you totally, as I often do. You do tend to bring out the worst in me .....
So yeah the g25-60 0.92 would be a decent alternative and could be worth a try. IMO spoolup will be about the same as what I have and emap very close to the same (better flow with worse efficiency balancing it out). So given that is how I honestly feel about it ...... it's not something I would do myself given the G30 has better options for more power with the 1.01.
I really think you need to try a few different combinations yourself to get a feel for how things work out in reality vs what you think might happen . I have found over and over and over with turbos and the Renesis that the result rarely matches the anticipated outcome . As an example I'm sure you think the g25 will spool better because of better moi etc............... but I don't . Simply because of the various combinations I've tried over the years and knowing there is always more to it than just moi ....like , efficiency of turbine and compressor , the extra rpms that need to be achieved etc. If you saw the wheel sizes of the 3582 next to the G30 you would wonder how the 3582 even gets close to the g30 in spoolup ---- yet .......it does.
As far as my decision to go T3 vs 'v' band ... That was on the sole basis of ease of fabrication and fitment ...nothing else. Not something you could know unless you had fabricated and attempted to install it yourself.
And for the G30 T3 open vs T4 twin scroll I still don't think that would achieve anything significant so I'll leave that one for you to try.
thank you Brettus, I get that and recognize the history between us as well as my role in it, but am hopeful that we can at least get past some of it to have a better dialogue between us
and yes, I understand why you did V-band/T3 swap, but also that possibly it’s still not being recognized why it makes a difference just as when we had the T4 housing inlet discussion. As I mentioned previously, the Garrett V-band housing is not a good choice fot a 2-rotor wankel. Not that it can’t be made to work, but is going to eat up a bunch of space and create more fabrication work funneling the exhaust streams together effectively. The larger rectangular openings of the T3 and T4 flanges lessen that consideration. Whether it’s a T3 or T4 sized volute isn’t the actual issue.
on the otherhand, the Garrett v-band housing is perfect for mounting a turbo directly on on a peripheral exhaust port housing, i.e. twin turbo 13B-REW
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Had a decent drive on my favorite road today .
I have to say ...I seemed to have underestimated how good this setup is . Lag ...............what's that ?
Check this out :
Turbo fully spooled same instant as throttle fully depressed ...........
Had a decent drive on my favorite road today .
I have to say ...I seemed to have underestimated how good this setup is . Lag ...............what's that ?
Check this out :
Turbo fully spooled same instant as throttle fully depressed ...........
I do not quite understand how its possible with more or less instant response. After all, there's inertia in the wheel, what do I miss?
Is it that engine at 5000+RPM and engine load of 50% produce enough exhaust energy to have more or less correct turbine speed for WOT and 10PSI? That you might have found a sweet spot, where
1. Turbine wheel get good initial speed at ~50% load
2. WOT is applied
3. Compressor loads turbine more, trying to slow turbine down(shortly increasing EMAP or forcing WG to open)
4. Almost immediately, chambers filled with WOT exhaust gases hit the turbine
5. Speed is more or less maintained
Plausible explanation -ish? If so, how is EMAP in the transition area?
I do not quite understand how its possible with more or less instant response. After all, there's inertia in the wheel, what do I miss?
Is it that engine at 5000+RPM and engine load of 50% produce enough exhaust energy to have more or less correct turbine speed for WOT and 10PSI? That you might have found a sweet spot, where
1. Turbine wheel get good initial speed at ~50% load
2. WOT is applied
3. Compressor loads turbine more, trying to slow turbine down(shortly increasing EMAP or forcing WG to open)
4. Almost immediately, chambers filled with WOT exhaust gases hit the turbine
5. Speed is more or less maintained
Plausible explanation -ish? If so, how is EMAP in the transition area?
Well ...it's not no lag at all, just very quick spool. Time from starting to depress throttle to 10psi is around 0.4 seconds, which is the same time as it is taking to open the throttle, so it's spooling up as the throttle opens.
At 5000rpm you have a LOT of energy in the exhaust and yes the turbine will already be spinning reasonably quickly.
Emap is around 7-8psi as it's transitioning from spoolup to constant boost.
Probably the biggest difference I'm noticing is coming out of low speed right angle corners in second gear ...... this setup is spooling a good 4-500rpm sooner than the 3582 was.
12-20-2021, 07:16 PM
Still quite a bit lower than the G30 1.01 AR you previously were using.
