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Old 06-12-2015, 03:09 AM   #1
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Brettus turbo 111 (the ultimate Renesis turbo ?)

As the title states ............ this is my attempt at making the ultimate Renesis turbo setup .

I've been running the Greddy system for about 6 years now and learned a heap from maximising that setup (See Brettus turbo and Brettus turbo 11 threads) but figured it was time to do something of my own design.

The engine : will be using my current engine . This engine has been doweled and had rx7 deep apex seals fitted along with increased oil pressure. However , once the turbo system is sorted I plan to refreash this engine as it is down on compression .

The Turbo :
This is a Garrett GT3582r unit . I chose this turbo after considering all the major brands . The main reason I went with it is because of it's relative compactness plus it had the options I was looking for . Other Garrett turbos I looked at ,that would also have fitted, were the GTX3076r, GTX3576r , GTX3582r . I settled on the standard 3582 for a few reasons :

*Discarded the 30 series when I realised they used the same turbine castings and CRHA as the 35 series so size is the same.
*It's more efficient than the smaller X76mm wheel in the range I want to operate it .
*With the design i'm looking at spoolup should be ultra fast , and I figured the smaller 76mm wheel would certainly go into surge without the benefit of a ported shroud. A ported shroud wont fit in a low mount design.
*The GTX3582r ,I felt, was just overkill for my whp goal .
*The cast compressor wheel is said to be more durable than billet when using pre turbo W/M injection.
*It's a lot cheaper than the GTX series

The Brettspeed manifold design :
This is where I'm hoping to make some inroads into making the Renesis turbo a viable alternative to an REW swap .
*Lowmount
*The turbine housing is a 1.01A/R twin scroll fed from the end ports.
*Wastegating will be a single 38mm wastegate through the siamese port .

I'm sure this will raise some eyebrows and create some scepticism . The system has been designed around making this work and I'm excited to see if it does .

Goals :
Reliable 400-450whp
16 psi by at least 3500rpm
Factory drivability





Turbo on dummy engine .




Edited for 4 port solenoid valve


A little more on why i went down this path ...

The 'Achilles heel' of the Renesis when turboed has always been the poor exhaust port flow. The siamese port is particularly poor and I have thought hard about how to improve on that . I even did tests on my last turbo setup where I removed most of the divider in the port. That test proved fruitless.
It occurred to me , why not take the siamese negative and turn it into a positive. The design above wasn't the first one i came up with by any means (and might not be the last) .
I see it as having huge potential it if does work , for the following reasons :

*unparalleled spoolup/response due to very small air volume in the manifold and the twin scroll turbine.
*large turbine housing to reduce backpressure and minimise the amount of air that needs to flow through the wastegate.
*Ability to get more flow out of the siamese ports than previously achieved due to the fact that backpressure at the wastegate can be close to zero if necessary, thereby allowing the siamese port to evacuate gas more easily . It should flow what it needs to flow (up to a point) to achieve the necessary pressure at the turbine.
* The wastegate should flow really well as it has perfectly timed pulses from either rotor and is 100% prioritised. Any restriction to flow should be at the siamese port itself , not the wastegate , even though the WG chosen is small by normal standards .
*no energy sapping major changes of direction for exhaust gases.
*Tubing to turbine does not have to carry gases that go through the wastegate so don't need to be large diameter .

Edit .Final design after a few iterations :





Pasting this summary for those who don't want to go through 53 pages to get to the crux of what was done here ....

Now that I've gone as far as i want to go with this build I think it's time for a bit of a summary on what worked/didn't work .

Siamese wastegate/twin scroll turbo :
From data i have it is obvious to me that I haven't unlocked any extra power up top by doing this . Then again I don't believe I've lost any either . The power the engine makes is as good if not better than anything I can compare it with . Low to mid range power being better than any other Renesis that has a similar top end , and also better than most with less top end potential as well.
Improvements in spoolup when paired with engine port timing mods are definitely there and are significant . I believe there are even further big improvements to be had here with the right engine modifications.
Improvements in boost control were an added benefit .
Overall , based on the improvement to spoolup alone I would say this modification is a success .

Bridgeport :
As mentioned above , this modification was very disappointing . I believe I lost somewhere around 20whp across the entire rev range by doing this . A slight reduction in spoolup/response being an added downside.
One surprising side effect that has been beneficial is fuel economy . I get really good fuel economy with a 30% ethanol blend . Mileage being as good if not better than any stock NA Renesis on 100% petrol.

Turbo :
I have tried a few different combinations of turbine housing and compressor wheel in the GT3582r base turbo .
In the final analysis I saw only minor improvements going from the stock GT 35r wheel to a billet GTX3576r wheel .
I found the larger 1.01 AR twinscroll turbine housing to be superior to the 0.83 in all respects .
The slightly better spoolup of the 0.83 did not translate to more power at the wheels in lower rpm ranges as you might expect.
For a low mount turbo the GT3582r AR1.01 with a To4B compressor housing was a good choice for the 350-400whp level . Fitting a better turbo (eg BW EFR ) down low would require a lot of firewall modification .
One day we'll see some great results from a top mounted EFR that will better what this setup is doing ........ not holding my breath on that one though.

E30 :
Running this compromise blend was a biggie and I would recommend it for anyone running similar boost in a Renesis . I think it's been a great compromise between fuel consumption , fuel system requirements and octane for a street driven Renesis running over 14psi boost.

Two stage exhaust system :
After my latest modification to this I would have to say that I would definitely do it differently if I was starting over . The simplest and cheapest thing I could have done would have been to just go straight to a 31/2" exhaust ...perhaps split into 2x 3" mufflers at the rear .
That said , the setup does produce a unique sound for a Renesis that I really like . It is no longer obnoxiously loud nor is there any drone at highway cruise . Not worth the expense though , I have to say .

Last edited by Brettus; 07-06-2017 at 12:08 AM.
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Old 06-12-2015, 04:56 AM   #2
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Great stuff.

What I'm afraid of it that exhaust is going to be too much of an restriction. At intake side, you'll have pressurized air, making it more dense, but after combustion pressure is lower, and volume is around double. Exhaust bends inside block, if I was to guess, does not look like its made to take massive amounts of flow, with its angle.

I'll definitively stay tuned to see how this goes. It's fantastic that you put so much time and effort into this!
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Old 06-12-2015, 05:05 AM   #3
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Great stuff.

What I'm afraid of it that exhaust is going to be too much of an restriction. At intake side, you'll have pressurized air, making it more dense, but after combustion pressure is lower, and volume is around double. Exhaust bends inside block, if I was to guess, does not look like its made to take massive amounts of flow, with its angle.

!
Have thought about this a lot and initially had the same concern . However , there are a couple of things about the design that have led me to think it will flow way more than in any other design .
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Old 06-12-2015, 06:56 AM   #4
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Oh yeah baby another Brettspeed project.
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Old 06-12-2015, 04:19 PM   #5
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Not sure if I'm clear on your intent.

Are you sending only the end ports to the turbo and dedicating the siamese port for wastegate flow only?
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Old 06-12-2015, 04:22 PM   #6
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Not sure if I'm clear on your intent.

Are you sending only the end ports to the turbo and dedicating the siamese port for wastegate flow only?
Yes ... that's the idea .
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Old 06-12-2015, 04:32 PM   #7
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hmmmm ... will have to mull that one over some. Not so sure that's a good idea under some conditions.
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Old 06-12-2015, 04:39 PM   #8
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hmmmm ... will have to mull that one over some. Not so sure that's a good idea under some conditions.
I've done a **** ton of mulling and the more I mull the more confident I get ... heh.
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Old 06-12-2015, 04:42 PM   #9
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have heard your hubris before, lol ...
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Old 06-12-2015, 04:47 PM   #10
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It will probably be fine. Only worry is the slightly higher back pressure causing hot spots, but WI will take away that danger. It also lets you use a divided housing.... yeah I love the concept. Make sure to use lots of water.
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Old 06-12-2015, 04:50 PM   #11
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have heard your hubris before, lol ...

Well put it this way ........
I wouldn't spend money on it if I didn't think there was a good chance it will work ,and if it does , it could be significant . So I'm prepared to take the risk .
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Old 06-12-2015, 04:53 PM   #12
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Only worry is the slightly higher back pressure
Do you mean from the restriction of the siamese ?
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Old 06-12-2015, 04:57 PM   #13
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if it stays closed for too long i.e. no flow, I'd be concerned about the temps the seals traveling that path will be abused by
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Old 06-12-2015, 04:58 PM   #14
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if it stays closed for too long i.e. no flow, I'd be concerned about the temps the seals traveling that path will be abused by
It only needs to be closed while the turbo is spooling up

I can control the WG with vacuum ,to stay open under cruise conditions .
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Old 06-12-2015, 05:07 PM   #15
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Yeah it's the restriction from closing the siamese. I wouldn't be worried about it, but I would keep a heightened awareness of it while tuning.
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I can control the WG with vacuum ,to stay open under cruise conditions .
Have you tried it yet? It's lovely.
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Old 06-12-2015, 05:12 PM   #16
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I'm confused.
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Old 06-12-2015, 05:17 PM   #17
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Yeah it's the restriction from closing the siamese. I wouldn't be worried about it, but I would keep a heightened awareness of it while tuning.

Have you tried it yet? It's lovely.
If the siamese can't flow enough , my concern is that I'll get boost creep as the turbine needs what it needs and will speed up the turbo if it gets too much back-pressure.
My hope is that , as there is no back-pressure on the siamese side , those ports will flow more . The WG can almost provide zero back-pressure if that is needed to allow the siamese to flow enough.


Have not tried opening the WG with vacuum yet ..... the trick will be in using a small spring and whether the EBC will get enough control with that spring in place.

Last edited by Brettus; 06-12-2015 at 05:19 PM.
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Old 06-12-2015, 05:17 PM   #18
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Hopefully it can flow enough to prevent overboosting.

otherwise kudos for the novel idea.
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Old 06-12-2015, 05:17 PM   #19
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I'm confused.

and ...
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Old 06-12-2015, 05:18 PM   #20
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Is this the first application of a divided housing turbo on a renesis?
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Old 06-12-2015, 05:23 PM   #21
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Is this the first application of a divided housing turbo on a renesis?
I believe so .
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Old 06-12-2015, 05:31 PM   #22
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Very very cool. The benefits....

I take it this is a contributing factor to your goal of 16 psi by 3500 rpms? (And carefully selected parts inside that monster of a snail)
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Old 06-12-2015, 05:35 PM   #23
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Very very cool. The benefits....

I take it this is a contributing factor to your goal of 16 psi by 3500 rpms? (And carefully selected parts inside that monster of a snail)
Absolutely ... The divided housing (albeit a large A/R )and small volume manifold should make it spool like no other Renesis .
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Old 06-12-2015, 05:40 PM   #24
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Brettspeed needs to start production of this little beauty.

Been crawling through your 11 thread, and the subsequent fuel pump thread. Thanks for all the great info. Your trial and error helps the rookies (me!) learn.
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Old 06-12-2015, 05:43 PM   #25
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I'm running a 4psi spring and force it closed to as high as I want with the EBC. Not a problem, just involves some creative plumbing. The siamese port should flow enough to prevent boost creep if you run a EBC with a low pressure spring. The real problems come from full pneumatic boost control systems with bad plumbing, closed loop with electronics makes most of that disappear.

Posted a picture of my WG plumbing on my build thread. Dunno if it's how you're doing it Brettus, but I like how it's worked out for me.

Last edited by Harlan; 06-12-2015 at 06:03 PM.
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