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Originally Posted by AAaF
(Post 4849180)
But isnt static pressure at outlet relatively close to atmosphere if you have an exhaust system that isn't too restrictive?
Yes, I've picked up that we cannot trust the absolute numbers from MAF, so that comparing what two different MAF's are giving is not sensible, but it might be that the same sensor would give us info regarding changes. For example, when you increase pressure to say 12psi, does your MAF reading go up by (14.7+12)/14.7 = 1.82 = 182%. I suspect that you see less, because filling is reduced from above 100%+ to something slightly less, for example 95%. Therefore (partly I guess), you need to have a bit more than 12psi to get a 182% increased reading from your MAF. This would might give us a picture about how filling/Ve changes during FI. Then we can use the numbers given by Mazda as reference for further estimations. Sounds sensible from your experience/numbers? ? It's just a loose theory in my head, caused by Teams input in his thread. And yes to above .I actually use the absolute load parameter as a guide to how much boost someone is running when I'm doing a remote tune ...it works out pretty accurate. |
OK, does the load double when pressure is doubled? Or a bit less?
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Originally Posted by AAaF
(Post 4849253)
OK, does the load double when pressure is doubled? Or a bit less?
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Pretty much as in...99%? 95%?
Sorry about the nagging, but because as I'm sure you've seen in Teams thread, the not too large difference between 13B-SI and 4 port Renesis made the difference between looking good and looking bad-ish, in the upper range of the chart. So the relatively small number changes does matter quite a lot apparently. |
As g/s is the main part of that calculation , and I'm not really confident in the g/s , I can't really be that accurate .
What are you wanting to do with the info ? |
Just calculate how system behaves when FI compared no NA. In my head, calculated load would work, when NA you are peaking at around 105% load normally(mine RX8 anyway). Anything above 100% is obviously due to good intake design, maintaining an optimum air velocity and scavenge resonances. So I would be more than surprised if you was seeing 210% load at 14.7PSI. Anything above 200% would surprise me. My theory is that if you see for example 190% at 14.7PSI, then filling is down from 105%, to 95%, due to the scavenging effects we have at NA.
Sounds far out? |
Gotya .
Something I have noticed is that the amount of power loss to drivetrain , as a % of the total , seems to be less as total power increases . So Ve per boost might not be a linear relationship but % power loss also drops and seems to more than make up for that . So many variables .............. |
Almost got me:) I thought about looking at VE vs pressure isolated, not mixing hp at all into the picture. Keeping everything else as identical as possible, same engine, same MAF, same stretch of road, same time of day and temp. Same shoes....:P
If we were to extract changes out from whp, then we are talking bloody Nobel price math. |
Originally Posted by AAaF
(Post 4849264)
Almost got me:) I thought about looking at VE vs pressure isolated, not mixing hp at all into the picture. Keeping everything else as identical as possible, same engine, same MAF, same stretch of road, same time of day and temp. Same shoes....:P
If we were to extract changes out from whp, then we are talking bloody Nobel price math. As boost pressure increases , the difference in pressure between whats at the fuel injector and what's inside the manifold decreases. The fact that I've never actually observed this phenomenon making any difference leads me to this conclusion: The maf curve I use (which is a tweaked continuation of the stock maf curve) gets more optimistic as it climbs. Hence my earlier comment about wanting to change my tuning method . By lowering Ve as boost increases I can have more realistic maf numbers. This wont make the Ve numbers accurate though, which is what you are interested in. |
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Originally Posted by AAaF
(Post 4849261)
Anything above 100% is obviously due to good intake design, maintaining an optimum air velocity and scavenge resonances.
Just popping in to remind you and everyone else that it’s all due to the intake design and only the intake design. Specifically for the Renesis engine there are ZERO scavenging resonances due to there not being any overlap between when the intake port opens relative to when the exhaust port closed. It’s essentially a mild supercharging effect solely from helmholtz resonance of the intake system. Mazda clearly recognizes this which is why they aren’t wasting any time with anything more than the most basic exhaust manifold design. The next generation 16x engine exhaust manifold design too. They wouldn’t just leave that on the table except there’s nothing on the table to start with. just couldn’t let that pass, so exit stage right ... Team out ... |
I might have been imprecise, I was aiming at scavenging Helmholtz resonances, not looking at exhaust side at all. So we agree completely here.
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Originally Posted by Brettus
(Post 4851334)
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They have the latest tech. available . Check it out here, 2nd post down ATM :
https://www.facebook.com/ProchargeTu...TJku2keIAdrlAM I think my turbo was one of the first to be balanced on this new machine . Here is the video they sent me.X axis is rpm and y axis is out of balance . The green line is the max. out of balance spec. The first run is showing it unbalanced . Second run is after they took some material off the nut : |
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Needs more shine :) you’re getting me all excited! |
only thing getting polished will be the dyno plot !
https://cimg8.ibsrv.net/gimg/www.rx8...81020ea241.jpg https://cimg1.ibsrv.net/gimg/www.rx8...9bf023bc89.jpg https://cimg6.ibsrv.net/gimg/www.rx8...873442714c.jpg https://cimg0.ibsrv.net/gimg/www.rx8...0630d98837.jpg |
Some initial Results of 3582 hybrid turbo :
Spool up is almost the same as the 76mm wheel (100rpm slower) Backpressure is down a little but not as much as hoped . AAaf ... here is the same run , one logging boost (14psi)and AFR the next absolute load and the last a virtual dyno. It's interesting that earlier in rev range the load is lower and doest approach 200% till after the apvs open . All depends on maf scaling of course but the general trend that you were looking for is there : https://cimg5.ibsrv.net/gimg/www.rx8...767162d073.jpg https://cimg9.ibsrv.net/gimg/www.rx8...74948d065a.jpg Torque at 5000 feels very nice :) Max whp isn't spectacular , but ambient temps are up high ATM so that would account for a few horses. https://cimg2.ibsrv.net/gimg/www.rx8...f32dc7dd06.png |
Looks like it ke there is potential on the top end. Some consideration on whether the exhaust system is potentially holding it back might be needed.
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Am trying to replace the short piece of pipe off the turbo outlet . It was a 2" silicone elbow going to a 2" ali. pipe then expanding out to a 2.5" about a foot along from there .
https://cimg6.ibsrv.net/gimg/www.rx8...7de84ac79c.jpg This was done to get around the steering rod .According to an online calculator this short section is resonsible for over 2psi pressure drop at the flow levels I'm running. I tried 2.5" but have given it up as impossible . Have ordered 2.25" tube to try and get that to work ...fingers xd. Once this is done I'll book the dyno and see what she will do this time ! |
Being an RHD owner, I've found this pipe is one of the more challenging components to install. Hopefully you see some worthwhile gains. You may also get a few whp from replacing the tight radius elbows in/out of the IC with some longer radius bends.
The other area I think can be improved on the stock greddy is increasing the diameter of the piping between MAF sensor and compressor inlet. I know you've worked on this - are you at the final stage of development for this part of your setup? Could you give us a bit of detail on what you did here? |
Originally Posted by JimmyBlack
(Post 4853122)
Being an RHD owner, I've found this pipe is one of the more challenging components to install. Hopefully you see some worthwhile gains. You may also get a few whp from replacing the tight radius elbows in/out of the IC with some longer radius bends.
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Originally Posted by JimmyBlack
(Post 4853122)
I know you've worked on this - are you at the final stage of development for this part of your setup? Could you give us a bit of detail on what you did here? Really the pipe above is the only restrictive piece left .... really hope i can make 21/4" work . I've done lots of improvements since my original 411whp dyno without being able to show any real peak power improvement . Instead of getting more power I was just getting the same power but at lower rpms . This trend is what lead me to my latest engine changes and with any luck ....the breakthrough I mentioned earlier. |
Old pipe vs new ..... After huge effort ...I got it to fit without fouling the steering column.
https://cimg6.ibsrv.net/gimg/www.rx8...97e3e57d0c.jpg Results are improving : this at 14.5psi on a hot day going slightly uphill - not too bad. https://cimg9.ibsrv.net/gimg/www.rx8...d2c7915931.png The big difference after fitting the pipe is that the pressure now is smooth rather than jumping all over the place. Turbine backpressure before : https://cimg2.ibsrv.net/gimg/www.rx8...01cb0af5f6.png After: https://cimg6.ibsrv.net/gimg/www.rx8...98cadb91c4.png Front turbine BP: https://cimg3.ibsrv.net/gimg/www.rx8...8ebb8fcb1e.png |
you mentioned that combustion pressures spike and thats the reason you limit rpm. is that influenced by backpressure?
do you feel that the VDI contributes much in your setup? |
It is def. a factor yes . As far as the VDI goes , I have that wired shut . The effect is gives on an NA car is nullified once you put boost into the engine .
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