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This is a thread for exchange of numbers when using MatchBot. Since our rotary is a bit different, it’s a jungle to get the correct numbers.
Your opinion is not welcome unless you present your numbers, when you believe numbers presented by others are wrong, preferably with some simple explanation and math if possible.
If you have a question, please explain thoroughly, preferably with numbers/pictures. I can guarantee that other people are wondering the same questions, so don’t be afraid of asking! Just put some effort into the question.
If you have numbers and charts for a good working setup, sharing is much appreciated!
And for the record, I'm not knowledgeable at this, I'm starting this thread to understand more. So do not expect good answers from me, but hopefully people will chime in, and together we'll get more knowledge.
Adding the initial picture of MatchBot for reference.
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.
*I'm using 70mm 0.92 AR turbine match which seems to line up well with my Garrett 68mm 1.01
Compressor A/R - Compressor performance is comparatively insensitive to changes in A/R. Larger A/R housings are sometimes used to optimize performance of low boost applications, and smaller A/R are used for high boost applications. However, as this influence of A/R on compressor performance is minor, there are not A/R options available for compressor housings.
So, since we are at relatively low boost, we would benefit from a relatively large A/R.
Back to MatchBot:
1. Why is your highest RPM set to 7600? When playing around, I've been at 8500 and even 9000, always thinking worst case.
2. When increasing max RPM to 8000, then do some guesstimations together with the numbers you represent, it looks like the EFR7163 that Team mentioned earlier is a good match, comments?:
3. Calculated Exhaust manifold pressure is 20.6PSI with a 70mm 0.92AR. This seems to be matching quite nice with your findings:
Originally Posted by Brettus
I just replace my flexible intake with a solid one and seeing some good results for turbine backpressure
Backpressure at 14psi with solid intake:
Looks like a 1.5-2psi reduction at peak ...which is equivalent to going up almost 2 steps in turbine A/R
First thing that I have become acutely aware of through my project is a quote from Hartman : "everything effects everything else". The parameter that reflects this the best IMO is turbine backpressure. Any change you make that improves or restricts flow will be evident in what turbine backpressure (EMAP) you achieve so it is well worthwhile to be able to log this parameter. What isn't so obvious is how EMAP affects performance. The relevant parameter in Matchbot for this is BSFC. This is not something matchbot can calculate and you can only guesstimate the effect of EMAP on BSFC through trial and error.
1/ I set my highest rpm to 7600 because that is where I've found peak horsepower to be with my setup. At lower boost with a less than ideal setup it will be at a higher rpm. As I've improved my setup , the peak hp-rpm has gradually got lower and lower. I believe this is all about how well the engine ports flow.
2/You are doing yours at 10psi and mine was at 15psi . At 10 psi with a free flow setup , all the pressure losses will be lower than what you show there .
3/Not an apples for apples comparison - same issue as in (2)
Also : you need to choose a turbine that matches your chosen turbo .... The 70mm0.92 is wrong for the 7163. I think you will find that backpressures will be quite high once you rehash pressure losses , put the right turbine in and alter the compressor efficiencies to suit the correct pressure losses.
Edit:
I just did the exercise with a free flow system the 7163 and the 63mm0.83 and got 21psi backpressure @10psi and 8000rpm which would be acceptable . But raise the boost to 15psi and you end up with about 32 psi backpressure.
This is what i got for my setup.
Not sure about how accurate the figure is, but I''ve driven my friend's manual E46 M3, and I can feel that my car pulls much harder than his M3.
I also drove another friend's HKS supercharged manual 86. that one is also slow compared to my 8.
Also : you need to choose a turbine that matches your chosen turbo .... The 70mm0.92 is wrong for the 7163. I think you will find that backpressures will be quite high once you rehash pressure losses , put the right turbine in and alter the compressor efficiencies to suit the correct pressure losses.
Edit:
I just did the exercise with a free flow system the 7163 and the 63mm0.83 and got 21psi backpressure @10psi and 8000rpm which would be acceptable . But raise the boost to 15psi and you end up with about 32 psi backpressure.
Why is 70mm 0.92A/R wrong for a EFR7163? Is it explainable, or is it just experience that is giving this answer? I can some recommendations to have a smaller turbine wheel than compressor wheel. I do not understand intuitively why a smaller turbine wheel is better. I get that there will be a gearing in tip velocity(tip of compressor vanes will go faster than tip of turbine vanes). I can also see that keeping turbine diameter within 15% of compressor is one recommendation. Are we looking for the same in our beloved rotarys, or do this change for us?
Example Application:
I want to make a 10PSI turbo system, because my engine is original and un- modded, and I want to run on normal pump gas.
Looking at MatchBot, EFR7163 looks like a decent compressor for the flow(see earlier post for picture). This compressor have a 71mm diameter. 71mm - 15% = 60.44mm minimum. Adjusting expansion ratio for 64mm 1.05AR, I end up with a maximum of 2.5(+exhaust back pressure).
Am I ready to order just by this? Sounds a bit to easy....
Word. In my previous post, I forgot to alter Volumetric efficiency. Below picture is more correct according to Brettus data set, makes a difference in Expansion ratio for turbine, pressure goes down from 2.5 to 2.35. So as :
Because that turbo doesn't come with that turbine ...it comes with a 63mm turbine only. The number 71 stands for 71mm INducer compressor and 63 stands for 63mm INducer turbine. Other turbos use different naming methods:
Garret 3582 means : 35 series frame size with an 82mm EXducer compressor
Precision 6262 means : 62mm INducer compressor with a 62mm EXducer turbine
Very confusing
IMO the smaller turbine is a good reason not to use that particular turbo as the Renesis is very sensitive to backpressure . I would go with the 7670 all day everyday to do a 10psi setup. Becomes doubly important if you plan to run pump gas.
For your post above ..IMO :
you have way too much pressure drop on the air filter restriction . A top mount can be very free flowing so something around 0.6 at 8000 is more realistic.
You probably have too much for intercooler assuming all your pipes are correct diameter and it's a decent sized IC: somewhere around 1.5 at 8000
Muffler ... if you are using a store bought catback system that could be 3-4 at 8000 . If you make a free flowing one it could be down around 2
I am trying to work this out. This is my work up photos.
if I am reading the graph correctly every chance I am not wouldn't the points I circled be producing more heat and outside efficiency range?
I know apples to cherries compared with bretus's charts but I am attempting to understand. What I seem to be finding is my head spinning.
would this be a better fit?
only thing that I changed is the turbo instead of the 70mm 1.22 a/r this one would be the 74mm0.92a/r
Last edited by Custom_ftr; 11-06-2018 at 10:48 PM.
Running any turbo renesis to 9000 is a really bad idea for a start . Use 8500 as your max. rpm and adjust volumetric efficiency at that rpm down to about 90%
Intercooler press drop will be more like 1psi at that flow and muffler could be anywhere between 0 and 7 depending on many factors IE cat, free flow exhaust etc
That 7670 will run 8psi just fine and spoolup up really well but the compressor is not really designed to run low boost in an engine that flows a lot of air .
Gonna bump this, while I bailed pursuing the turbo project head-on, it still exists somewhat in the background as a future endeavor. I still say your numbers are off on the 7163. This is essentially a 3071R on steroids with better response and compressor flow.
If you go back and reference your own threads regarding the MM 3071R/Greddy conversion then it’s clear that this is not the high rpm power option, which was never my goal nor do I see it as the goal for any low mount position. I’ll give you credit for stuffing that bigger Garrett down there, but it has it’s own limitations wrt response and fabrication.
Which good luck stuffing a 7670 down there. This is why I made the 7163F(v) selection and it’s a tight fit despite being EFRs smallest frame size. Take the results from Chickenwafers MM/Greddy dyno and expand the low rpm curve to the left with more top end peaking around 6500 with a 7000 redline. That’s how I see it anyway.
Which good luck stuffing a 7670 down there. This is why I made the 7163F(v) selection and it’s a tight fit despite being EFRs smallest frame size. Take the results from Chickenwafers MM/Greddy dyno and expand the low rpm curve to the left with more top end peaking around 6500 with a 7000 redline. That’s how I see it anyway.
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Yeah I do think the 7163 is a good idea for what you suggest on a four port ....with a few caveats . Must use high octane fuel, very efficient intercooling, good engine cooling,careful tuning and some strengthening internally for all that torque.
For the average joe turbo install on a six port ..... it's a really bad idea though.
I definitely wouldn’t be revving it out or opening up the APs.
Good that we can finally agree on that
Originally Posted by TeamRX8
Here is the reference I was referring to; 3071R @ 13.5psi, 51% meth/H2O injection, and 91 pump gas.
Yeah ... remember it well . It def. wasn't 13.5psi though ...pretty sure the EBC faulted to max. on that run so boost at peak torque would have been 18ish. He got lucky, is all I can say about why it survived that.
09-28-2018 | 12:52 PM
