Turbo manifold styles- Absurdflow lowmount vs ramhorn, which for maximum power? - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 01-29-2011, 10:57 PM   #21
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log
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Old 01-30-2011, 12:16 AM   #22
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Quote:
Originally Posted by 1slowna View Post
http://i89.photobucket.com/albums/k2...301/BMW_02.jpg
i am pretty sure bmw knew what would make the best power and the best low end torque when they built this manifold for their 1980s 4cyl f1 engine. that engine made over 1000hp at 2.0l displacement on 74 psi during qualifying, and thats with older turbo technology then we have today.
1.5l i4
5.5 bar around 1300hp
almost 80psi


They also used different fuels than we do back than.
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Old 01-30-2011, 12:19 AM   #23
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Quote:
Originally Posted by TurboTim View Post
I am not sure why Savington would get a ramhorn from Abe/ARtech when he could get one from me for raw material cost. Then again Abe is more official/professional than I am at it and would be a better choice for production builds.
Interesting that you might want to do a Ramhorn setup. I will be talking to you about that.
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Old 01-30-2011, 04:36 AM   #24
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Quote:
Originally Posted by TurboTim View Post
I am not sure why Savington would get a ramhorn from Abe/ARtech when he could get one from me for raw material cost.
Argh yees, I meant you!
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Old 01-30-2011, 05:13 AM   #25
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Ramhorn would create more power, take a look at Full-Race and a lot of big name high horsepower Honda guys. The big horsepower guys run either a equal length ramhorn, or a header style manifold (top mount).
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Old 01-30-2011, 07:23 AM   #26
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Quote:
Originally Posted by Techsalvager View Post
They also used different fuels than we do back than.
Toluene, IIRC.
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Old 01-30-2011, 12:16 PM   #27
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Quote:
Originally Posted by 1slowna View Post
i am pretty sure bmw knew what would make the best power and the best low end torque when they built this manifold for their 1980s 4cyl f1 engine. that engine made over 1000hp at 2.0l displacement on 74 psi during qualifying, and thats with older turbo technology then we have today.
LOL @ "low end torque" and "F1" uttered in the same sentence.

To help the OP understand...

If your goal is to reduce the boost threshold of a 2871 or 3071 turbo from say 4k RPM to 3.5k RPM on our cars, long exhaust runners are counter to your goal. A low mount short ram will be superior while sacrificing very little in high RPM exhaust flow/max power.

Long runner, tuned, equal length, turbo manifolds are a max power design decision. The design criterion is for max exhaust flow in an RPM window well above boost threshold. Time to reach target boost (aka spool) is minimized within this RPM window.

The reason you see these manifolds across all forms of racing is because racing is essentially sustained high RPM operation. The time spent from idle to 4k RPM is so small it is irrelevant

While it is all about "area under the curve" you only measure the area under the portion of the curve which is relevant to your operating range. Racing neglects a portion of the curve which is of key relevance to most of us.

That is all, carry on.
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Old 01-30-2011, 01:13 PM   #28
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nah if you want to lower the boost threshold on a big turbo, advance the intake cam 3-4 degrees.
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Old 01-30-2011, 01:47 PM   #29
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The best manifolds keep the turbo attached after a 30 minute track thrashing. You can make 300whp with basically any manifold design, but not many people can handle 300whp on track. Address other issues first. I love you Erin.
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Old 01-30-2011, 03:42 PM   #30
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Some rough numbers to think about

1.8l exhaust manifold gasket hole perpendicular to flange -- 48.8mm X 29.8mm, Area = 1264 mm^2

Stock 99 head perpendicular to throat-- 45mm X 23mm, Area = 921 mm^2

Ported 99 head (Replika or FM) perpendicular to throat -- 47mm X 24mm Area = 1004 mm^2

1-1/4” schedule 40 pipe -- ID 35mm Area = 962mm^2

1-1/2” schedule 40 pipe – ID 41mm Area = 1320 mm^2

Area 4 of the runners gets necked down to before entering the volute on the turbo is ~792 mm^2 as a guess.

Bob
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Old 01-30-2011, 04:35 PM   #31
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Quote:
Originally Posted by MazDilla View Post
To help the OP understand...

If your goal is to reduce the boost threshold of a 2871 or 3071 turbo from say 4k RPM to 3.5k RPM on our cars, long exhaust runners are counter to your goal. A low mount short ram will be superior while sacrificing very little in high RPM exhaust flow/max power.
To help you understand, all I asked about was maximum power. At no point did I mention boost threshold. If that were my goal I'd likely to have said that.

Quote:
Originally Posted by MazDilla View Post
Long runner, tuned, equal length, turbo manifolds are a max power design decision. The design criterion is for max exhaust flow in an RPM window well above boost threshold. Time to reach target boost (aka spool) is minimized within this RPM window.
Read this: http://www.sr20forum.com/745652-post1.html

See actual data.

Quote:
Originally Posted by Bond View Post
The best manifolds keep the turbo attached after a 30 minute track thrashing. You can make 300whp with basically any manifold design, but not many people can handle 300whp on track. Address other issues first. I love you Erin.
I don't think an ARTech ramhorn will have issues on track. Not in SCH40 mild. Talked to Abe about it and he says it should hold up fine.

Love you back Mikeypoo. <3
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Old 01-30-2011, 05:50 PM   #32
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Quote:
Originally Posted by Nagase View Post
...all I asked about was maximum power. At no point did I mention boost threshold. If that were my goal I'd likely to have said that.
You asked why some members on this board ranked an Absurdflow low mount (aka unequal length mini ramhorn) higher than an equal length long runner ram horn.

Boost threshold is why. Lowering the boost threshold of a large turbo is key to achieving "max power" as in "maximizing the area under the curve", when you can take advantage of a wide power band but can't rev to the moon.

Quote:
Originally Posted by Nagase View Post

Read this: http://www.sr20forum.com/745652-post1.html

See actual data.
Your link compares an equal length long runner bottom mount ramhorn to an extremely crude log (on a VTEC honda motor).
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Old 01-30-2011, 05:53 PM   #33
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Quote:
Originally Posted by MazDilla View Post
You asked why some members on this board ranked an Absurdflow low mount (aka unequal length mini ramhorn) higher than an equal length long runner ram horn.

Boost threshold is why. Lowering the boost threshold of a large turbo is key to achieving "max power" as in "maximizing the area under the curve", when you can use take advantage of a wide power band and can't rev to the moon.
Better flowing doesn't mean better area under the curve. If I put on a T4 turbo, it will flow better than a T2 turbo, but that doesn't mean it'll have a better curve. This thread is about maximum peak power, you're completely off topic.

Quote:
Originally Posted by MazDilla View Post
Your link compares an equal length long runner bottom mount ramhorn to an extremely crude log.
Obviously. It's an actual back to back dyno test, though. Do you have a better one to link to?

You should notice that the dyno graphs were /exactly/ the same until the ramhorn 'kicked in' though. That is interesting in and of itself.
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Old 01-30-2011, 05:57 PM   #34
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Passion you have. Logic you lack.
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Old 01-30-2011, 05:59 PM   #35
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Quote:
Originally Posted by MazDilla View Post
Passion you have. Logic you lack.
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Old 01-30-2011, 06:06 PM   #36
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I think the results of a test like that on a bp would yield less drastic peak power differences due to the much worse flowing head we have, but the overall results would be similar IMO.

I remember a thread where begi did a back to back of their log vs s4 and it was something like 7-10hp difference up top? Don't quote me on those numbers but it was something small like that.

Now since an absurdflow will flow circles around a log (pun intended) I'm going to guess the difference between it and a ramhorn would also not be very drastic, but the "top power" winner will still be the ramhorn. IMO
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Old 01-31-2011, 09:37 PM   #37
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So I have been talking to Tim about possibly building me a V-Band setup. I have asked him about a few of his designs and these are what he has sent me so far. What one do you guys think would work the best.

1.

2.

3.

4.

We also have Abe's ramhorn as follows.
5.
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Old 01-31-2011, 09:40 PM   #38
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I've been talking to Shuiend about this, linked him to Abe's setup. There's a few people interested in a ramhorn at the moment, at least.

So far Abe's setup still looks like it would flow the best, and it seems to be closest to what I'm seeing from drag cars, specifically turbo Honda B/K series engines. Full race, for example.
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Old 01-31-2011, 09:55 PM   #39
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Quote:
Originally Posted by shuiend View Post
So I have been talking to Tim about possibly building me a V-Band setup. I have asked him about a few of his designs and these are what he has sent me so far. What one do you guys think would work the best.

4.

Ahh Tim, so is that the twinscroll mani you said you would CAD out for me?

Are all the runners actually equal length? Looks like some are not
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Old 01-31-2011, 09:57 PM   #40
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Oh and for non twinscroll, #3 is pretty sick and my favorite other than twinscroll but it looks like it comes off the head a decent distance. looks like the turbo would hit the subframe?
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