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Thread: 8k redline

  1. #1
    Active Member Two Rings
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    8k redline

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    So I am getting my Jhm rebuilt heads put on my car will this make it possible to have an 8 k redline now

  2. #2
    Senior Member Three Rings
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    Quote Originally Posted by P-arty1789 View Post
    So I am getting my Jhm rebuilt heads put on my car will this make it possible to have an 8 k redline now
    No, you canít just with the heads unless you donít want a working motor for very long. You need a built bottom end as well.

    https://youtu.be/zrNUcEwCAIQ


    Sent from my iPhone using Tapatalk

  3. #3
    Veteran Member Four Rings q_dubz's Avatar
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    Quote Originally Posted by P-arty1789 View Post
    So I am getting my Jhm rebuilt heads put on my car will this make it possible to have an 8 k redline now
    Not without HD valve springs and the whole nine. I wouldn't trust the rods at that level either.

    Regardless you don't make power up that high anyway.

  4. #4
    Active Member Two Rings
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    I have had valves an to springs an retainers but I think the power falls after 7300 or 7500

  5. #5
    Veteran Member Four Rings q_dubz's Avatar
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    Quote Originally Posted by P-arty1789 View Post
    I have had valves an to springs an retainers but I think the power falls after 7300 or 7500
    More like 6900t

  6. #6
    Veteran Member Four Rings Mr. Corey's Avatar
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    I don't go above the stock red-line with my setup..... as the power band is very responsive and rev happy in combination with the HD heads along with all the other bolt-on JHM goodies. Like Q mentioned the rods are the weak link in the equation if your pushing the car to hard.
    B6 Nogaro with lots of mods
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  7. #7
    Veteran Member Four Rings q_dubz's Avatar
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    Quote Originally Posted by Mr. Corey View Post
    I don't go above the stock red-line with my setup..... as the power band is very responsive and rev happy in combination with the HD heads along with all the other bolt-on JHM goodies. Like Q mentioned the rods are the weak link in the equation if your pushing the car to hard.
    Tho I haven't heard of anyone throw a rod from over rev. Typically redlines are determined by valvetrain first.

  8. #8
    Veteran Member Four Rings Mr. Corey's Avatar
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    Quote Originally Posted by q_dubz View Post
    Tho I haven't heard of anyone throw a rod from over rev. Typically redlines are determined by valvetrain first.
    True... gotta bust out a $$$$$$ shift for that
    B6 Nogaro with lots of mods
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  9. #9
    Senior Member Four Rings ven0m's Avatar
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    Stress level on internals rises exponentially between 6-7k rpm forces, 7-8k and 8k+. So no, forged rods, pins and crankshaft would be required to hold it together for a longer period. If you don't mind throwing a rod every now and then, go for it. You would have 8 to spare.

    Also BNS motors (RS4) which red-line at 8.250rpm is in practice on track pointless to shift at redline as the ideal power-band is 5-7k so you always shift up once you hit 7k and if fast enough you "catch" it on 6k rpm to continue pushing!
    Jeremy Clarkson: "So when you were saying that it wonít slide, what you meant was, ĎI canít slide it.íď
    James May: "Yes."

  10. #10
    Veteran Member Four Rings ZimbutheMonkey's Avatar
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    Quote Originally Posted by P-arty1789 View Post
    So I am getting my Jhm rebuilt heads put on my car will this make it possible to have an 8 k redline now
    As others have said, these cars simply won't make power over 7000 RPM.

    After 3 years and thousands of hours spent building/driving/logging and researching these engines, I've come to the conclusion that the limiting factor on their high end power is due in most part to the intake manifold design. Although the stock cams aren't great, when you look at how horrible the short runner intake ports are shaped I can't imagine that even an aftermarket set of cams would be able to deliver their full gains breathing through a row of rectangular pipes right next to each other...

    Don't believe me? Aside from the 4.2 V8 found in the B7 RS4 and R8 and the 5.2 V10 in the R8 Find me any other N/A Audi engine that can breathe at over 7000 RPM, even with full bolt-ons.

    Why can the 4.2 RS4/R8 and the 5.2 R8 engines make power past 7000 RPM? because they're the only N/A Audis with single length, bellmouth runners, end of story.

    Just to back up my assertions with some evidence. Here's a CFD comparison between 3 runner types, 1) straight pipe 2) radiused and 3) bellmouth

    CFD PLAIN PIPE END by zimbu themonkey, on Flickr

    CFD RADIUSED PIPE END by zimbu themonkey, on Flickr

    CFD BELLMOUTH PIPE END by zimbu themonkey, on Flickr

    As you can plainly see by the g/sec flow rates, the bellmouth outflows the plain pipe by 20% (36 g/sec vs 30 g/sec). If we were to apply that to the S4 intake manifold and went with a conservative 10% increase in airflow, at stock levels, that would equate to 35 CHP, and with full bolt-ons, about 40 CHP.

    If, however, the gains were closer to what the CFD simulations predicted, a properly designed intake manifold for these cars could make upwards of 60-70 CHP....

    Something to think about eh....? (whistling nonchalantly)
    Last edited by ZimbutheMonkey; 10-13-2018 at 01:38 PM.
    This B6/B7 S4 forum is brought to you by the refreshing taste of Kool-Aid... OH YEAH!!!!!

    My car has a real tune. Tuned by me. Just because you're not smart enough to tune your own car don't ruin a thread.

  11. #11
    Active Member Two Rings
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    Yea deff something to think about so the inside of the intake manifold needs to be redesigned better but doesnít that designed help air flow into valves or no to bad Simone has not done this would be nice mod

  12. #12
    Veteran Member Four Rings q_dubz's Avatar
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    funny to see this here, I was just talking to a guy THIS MORNING who 3D printed a bellmouth for his S4 TB inlet and gained 10% improvement in MPGs.
    Last edited by q_dubz; 10-15-2018 at 09:23 AM.



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