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Just picking a little man. I don't know about greddy, but I've just about found the way to wrestle mine in and out. I can manage to get it without touching the engine mount on the other side. The hardest thing for me is getting the 2" pipe from the turbo hooked up. That's a Tight effin squeeze.
Something isn't right. No way should it basically match the larger housing to 5k, then hold essentially the same differential through the upper range. The peak differential seems right to me, but it should have been stronger down low then tapered off and crossed over more gradually higher in the powerband.
Well I doubt it's any higher than with the Greddy derivative. It could be anything, mechanical or otherwise.
Too bad we can't get a GTX3576 comparison
For a real-world example showing the effect of compressor efficiency on engine power, we go back to the Novak Time Attack Subaru. The dyno plots show a GTX3576R compared to a GTX3582R with the two turbos being tuned by Church Automotive to make the same power. Of course the GTX3576R spools up faster (the GTX3576R is a ~600whp turbo whereas the GTX3582R is ~725whp), but you can see for the same torque and power a higher engine speeds, the GTX3576R requires more boost pressure compared to the GTX3582R. This is due to smaller 76mm compressor having lower efficiency compared to the 82mm compressor and the high engine speed operating points. The lower compressor efficiency of the 76mm compressor means more shaft power is required from the turbine. Therefore, the turbine pressure ratio is higher resulting in greater back pressure. Thus, higher compressor boost pressure from the smaller compressor is required to make the same engine torque
I actually think I know what the problem was . But seeing as I'm not having much luck lately I thought I would wait till plan D is tested before posting about it.
Thanks . Ironically , the reason it didn't work (which I think was because of something else i did at the same time as fitting the housing) may well have pointed me in the right direction ...
Quick update :
Plan D .... (convert to 0.83 single scroll ) got all my torque back after losing it on plan C . I'm fairly sure making a change to the Siamese sleeve is what screwed up plan C so badly.
BUT ............. LOST about 150-200 rpm of spoolup .
Plan E : sending turbo back to supplier to re-machine the compressor cover . I think it has too much clearance on the radius part and possibly the face adjacent to the exducer . Crossing fingers !
Just curious what you tried to do with the sleeve? You previously mentioned it being cracked and having the option to replace it. Did you just remove it entirely?
I would still suggest that the size relationship between the compressor and turbine is not in your favor for a rotary application.
Just curious what you tried to do with the sleeve? You previously mentioned it being cracked and having the option to replace it. Did you just remove it entirely?
.
Just modified it for more flow (and so it wouldn't fall to bits). Similar to the mod i did a few years back but less aggressive. So the extra flow , i think , put a much higher % of gases down one scroll of the turbo making it unbalanced and possibly increasing backpressure/reducing torque as a result.
Originally Posted by TeamRX8
I would still suggest that the size relationship between the compressor and turbine is not in your favor for a rotary application.
I still say it's the turbine/AR housing combo that is the critical thing . This turbine , with the 0.83 housing is possibly too small for 400+ but seems fine for around the 400 mark . But till i get a decent spoolup there isn't much point even talking about a bigger turbine.
Quick update :
Plan D .... (convert to 0.83 single scroll ) got all my torque back after losing it on plan C . I'm fairly sure making a change to the Siamese sleeve is what screwed up plan C so badly.
BUT ............. LOST about 150-200 rpm of spoolup .
Plan E : sending turbo back to supplier to re-machine the compressor cover . I think it has too much clearance on the radius part and possibly the face adjacent to the exducer . Crossing fingers !
Been hanging out for an update/announcement. This thread has more suspense than X-factor.
A few Qs.
Will you be moving back to the larger twin scroll turbine once the compressor housing has been re-machined?
Will you be retaining the modified siamese sleeve?
If retaining the (suspected) higher flowing siamese sleeve, will you increase the pipe size after the siamese primary meets with the front port, between this collector and the turbine flange? If the siamese port is flowing that much more, you'd probably want to reduce the backpressure now experienced by the front rotor. Of course this would likely hurt your spool up.
Also in hind site after your testing to date, is the T3 still preferred over the T4? You may have covered this earlier in the thread, but rough calculations for x-sectional area (units are mm squared):
Been hanging out for an update/announcement. This thread has more suspense than X-factor.
A few Qs.
Will you be moving back to the larger twin scroll turbine once the compressor housing has been re-machined?
Will keep the 0.83 single scroll in till I resolve the spoolup issue ... if it ever gets resolved.
Originally Posted by JimmyBlack
Will you be retaining the modified siamese sleeve?
If retaining the (suspected) higher flowing siamese sleeve, will you increase the pipe size after the siamese primary meets with the front port, between this collector and the turbine flange? If the siamese port is flowing that much more, you'd probably want to reduce the backpressure now experienced by the front rotor. Of course this would likely hurt your spool up.
For now i will retain it . If/when i put the 1.01 back in maybe i should swap back to the stock siamese then
The point is .......... with a smaller AR housing , more flow goes through the WG ,which is serviced by the siamese.
No change in pipe size necessary as there shouldn't be additional flow through that pipe at peak hp as the WG will be flowing almost half of what the engine produces.
Originally Posted by JimmyBlack
Also in hind site after your testing to date, is the T3 still preferred over the T4? You may have covered this earlier in the thread, but rough calculations for x-sectional area (units are mm squared):
T3 Flange: 2545
Total Reni Exhaust Port Area: 3028
T4 Flange: 3773
Yes but ............. with an external WG only roughly 55% (edit .... not 45) of exhaust gases go through the turbo flange at peak.
08-29-2015, 04:35 PM
