02-22-2022, 03:23 AM | #23 |
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This, if you need to drop timing and add more boost then there is way to much backpressure in the system or heat!. It's better to reduce the backpressure to get the same power with lower boost. People don't understand much diffrence lowering the backpressure does
Last edited by Amazinjoey; 02-22-2022 at 03:41 AM.. |
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02-22-2022, 03:58 AM | #24 | |
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The cat makes the biggest difference I've seen many stock + downpipe compared to MPPSK + downpipe, not much of a difference.
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02-22-2022, 07:55 AM | #25 | |
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There are so many things the tuner could be changing that would mess with timing. |
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02-22-2022, 07:58 AM | #26 | |
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02-22-2022, 09:43 AM | #28 | |
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I can take my friend car for example how opened my eyes to this, He is not running a BMW but a Saab 9-5, 4 cylinder with a TD04HL-19T. Which is a smaller turbo than what is on his B58. He was doing 350hp with 1.7bar, running 3 inch catless to 2.5 inch exhaust, and the backpressure was a b*tch , but then he went 3.5 inch downpipe to 3 inch he could get the same power with 1.3 bar and higher timing Now he is doing 450-500 HP with 1.3 bar and the same turbo, just by minimizing the Backpressure and optimizing the flow. Here is video of him explaining, shitty audio but a really good explaination : Acceleration video: So Imaging if a 4 cyl car with a smaller turbo has this problem and needs a bigger exhaust then how will not 6 cyl with bigger turbo not need the same Last edited by Amazinjoey; 02-22-2022 at 09:50 AM.. |
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02-22-2022, 11:15 AM | #29 | |
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02-23-2022, 02:06 AM | #30 | |
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My advice to you never compare totally different cars with different brands from different eras, if your friend's car has a restrictive exhaust doesn't mean all the cars in the world has a restrictive exhaust.
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02-23-2022, 07:10 PM | #31 |
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I'm running the NGK's ... so far so good. Not getting any misfires or anything like that.
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02-25-2022, 10:11 PM | #32 | |
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I used to have a 97 Eagle Talon TSI AWD back in high school that was a 2.0L 4 cylinder turbo and made 470 whp on a 3" inch exhaust .... it was a massive 60-1 turbo that flowed quite a bit of air up top (didn't hit full boost till about 4.5K rpms thx to the limited displacement ... but was still fun!). I really don't know enough about required back pressure based on the amount of airflow produced by a turbo to opine with any level of credibility, but I have not yet read a single post on our cars that suggest our exhausts are bottlenecks... who knows! Not sure what size our cat back exhausts are, but aftermarket downpipes seem to be ~4 inches, which is absolutely massive. Think of the percentage difference between 3 and 4 inches for example ... its 33.3%. Meaningful delta. That said, my car was like 340 whp stock ... it made 510 whp on 93 ... and im now dialing in on E85 with 3-5 PSI more boost, and almost 5 degrees more on timing ... so its a LOT of air ... maybe you are onto something here .... What do you think guys????
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Last edited by talontdone; 02-25-2022 at 10:15 PM.. Reason: Missed a few important details |
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02-26-2022, 08:06 AM | #33 | |
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On a production car, this is not true. They will all have slightly difference compression, slightly different flows, slightly different timing, etc. All of that impacts the power delivery. The more cylinders the engine has the more this starts to get averaged out, and is very apparently when you are down in the 1-2 cylinder range. And I wouldn't compare Saab to BMW as an apples to apples. There has been dyno tests (many of them) that shows upgrading our exhaust is mainly for sound, with very little gains (IE low change in backpressure). |
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02-27-2022, 07:36 PM | #34 |
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02-27-2022, 10:59 PM | #35 | |
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Its actually a 77.7% difference. It's all about cross sections area, which is pi*r^2. X-sectional area of a 3" pipe = 7 sq in X-sectional area of a 4" pipe = 12.6 sq in
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02-28-2022, 01:57 PM | #36 | ||
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Here is a more detailed explaintion of backpressure, in the forum there is also some simulation showing backpressure and flow Source: https://www.trionictuning.com/forum/...p?f=46&t=11945 Quote:
Last edited by Amazinjoey; 02-28-2022 at 02:11 PM.. |
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02-28-2022, 09:47 PM | #37 |
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I spoke too soon ... latest revision and getting timing pull and car is completely cutting out at 6K rpms (not sure if its misfire or fuel cut). Have been advised to get new plugs and gap down to "0.020 .... sad part is I just put new plugs in maybe 4K kms ago (~3K miles) ... this E85 thing is getting frustrating.
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02-28-2022, 10:28 PM | #38 | |
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03-01-2022, 02:19 PM | #39 | |
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I really hope I'm not getting counterfeit plugs ... I get them from an extremely reputable BMW performance shop here in Calgary.
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03-01-2022, 10:48 PM | #40 | ||
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03-02-2022, 08:12 PM | #41 | |
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It's funny that people are saying to go with Champion plugs when they were stock and everyone had issues with them. Not even a year ago everyone was switching to NGKs because of it. |
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03-03-2022, 04:47 PM | #42 | |
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03-16-2024, 03:35 PM | #43 |
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Normally higher boost lower timing is safer, that is why tuners choose that path out of the others you can use.
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