Turbo manifold styles- Absurdflow lowmount vs ramhorn, which for maximum power?
 

In wanting to push a given turbo to the greatest power, would a ramhorn manifold (assuming well made, I'd been wanting ARTech) make more or less power than an Absurdflow low mount?

I'd been operating on the assumption that nothing beat an equal length ramhorn for strictly maximum power potential, but in doing searches I read that the ramhorn was put down the list, and under the low mount. I'm at a bit of a loss as to why.

Could anyone shine light on this?

Theoretically, yeah, but nobody's ever done the back-to-back on it. I might get to it this year if I decide to swap manifolds.

Some observations

If you look at most any seriously fast professionally done import turbo drag motor they are all long runner equal length jobs. I suspect some of those guys know what makes the most power.

What is also interesting is if you look at any WRC cars by teams with million dollar budgets that hav to run a serious intake restrictor limiting top end power thus making low end torque and turbo response the most important thing they are trying to gain they are also long equal length turbo manifolds that look more like a full header with a turbo stuck on the back.

Bob

Twinscroll manifold and twinscroll turbine housing for super mostest power.

Equal length twin scroll will make the most power out of your turbo. Doing twin scroll lets you run a bigger A/R with killing spool. This will allow you to flow more air then your comp wheel would ever flow.

Awesome, but not what I'm asking.

OK fine I answer the question.

No, I would not think that low mount beats ramhorn/long tube for peak power potential.

BUT low mount has kind of mid-length runners, and the runner merge area is not at 90 frikken degrees like a log. So I think that for overall driving a low mount should have better spool and power under the curve than a ramhorn. Prob better for daily driving and shiz.

If however you are spinning your motor to 8500 RPM like a boss, I think there's probably a strong case for long runner.

Savington, if you get a ramhorn from Abe, are you going to increase your redline?

Would be interesting to see a back-to-back.

I like the ABSURDflow if for no other reason than its packaging, sturdiness, and simplicity. Seen only two in person and they both looked damned solid.

How does the BeGi S4 fit in this story?
That is equal length, isn't it?
I prefer to talk about max torque over a wide RPM range as it is giving more the a big peak in a small RPM range. There are a lot of tuners claiming +500 hp and I do beleve them. When viewing dyno charts you see the 500 hp can't be used in a normal way as it just there at redline and under 5500 rpm or so it is doing worse than a well balanced performance engine.
The same thing for comparision: I drove an old Alfa 75 1.8T. At 3000 rpm boost kicked in, causing the car going sideways and left me with hell of an impression. Wow, that car was superfast! While... It wasn't. Drove the same car with a GT2860 instead of a T3 and it felt quick bit did not kick ass as the T3. Well.. It beated the T3 in every way. But the torque came so smooth that it felt smooth. It did not lose traction, it just went forward very fast. It is not just BHP's that count. It's how they are developped.

Dyno's should have some average function build in. They should not just give peak BHP but it should be measured over the whole RPM range.

Whatever doesn't choke you up top will make the most power.
So if there are no limits in the turbo manifold for restrictions you will not be lacing that out

You guys are going way off topic.
We all know about the curve argument. OP asked about maximum power.

All the f/i big dogs in the drag racing world use ridiculously long equal length runners. It has been proven time and time again that it nets the most power on other cars. I don't see any reason for that not to be true on a miata.

Though since our heads flow so horribly it might not be as beneficial to use that concept on our cars unless ported+good im+cammed/etc.

18psi has a good point there, this is why i think a twin scroll will get you the most whp and wtq.

Guys guys, I know what the F1/WRC/Drag racing guys do. That's why the absurdflow lowmount being put higher than the ramhorn confused me:

https://www.miataturbo.net/showpost....9&postcount=11

That's what I'm talking about.

In terms of max power and spool time a long runner equal length manifold is the best bet. The argument i always see against this is that theres more volume to fill before the gases hit the turbo so it takes longer but this is ridiculous statement because the manifold is already "primed" so to speak with exhaust gases before you even hit the throttle. also if this theory were true rear mount turbo kits would be absolutely worthless on all cars and i have seen first hand how well a rear mount kit can preform.
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.

Any PS and AC friendly versions yet?

I will say I have seen a lot of longer runner manifolds that I think used too big of tubing. I think you loose more energy expanding the flow and slowing it down into a large runner and then compressing it and accelerating it through the turbo than you do if you make runner cross section area closer to the area of a gasket match or slightly smaller so you keep more constant velocity between the head and the turbo inlet. Your likely to disturb smooth flow as well. Miata exhaust ports aren't that big.

Bob

Hooking the manifold up to a blower and blowing constant velocity air through it and measuring flow resistance is not quite the same as hooking it up to an engine with periodic flow pulses phased across different runners and having the presence of reflecting waves.

Bob

I am not sure why Savington would get a ramhorn from Abe/ARtech when he could get one from me for raw material cost. :dunno: Then again Abe is more official/professional than I am at it and would be a better choice for production builds.

In an ideal world I/we would have back to back testing on runner lengths/designs and runner diameters but this ain't no ideal world and everyone will still have their own opinion on the matter. With zero actual real world experience to form my opinion, I think a short ram manifold would tend to be more durable for track usage and for most setups (stock-ish engine and small-ish turbo) perhaps more area under the curve (again, w/o actual data that's a guess). If doing a drag or rally car where you either have fancy antilag and/or running in a rpm small window I'd do with a longer tube/equal length jobbie. Or if you want to look cool with a maze of pipes under your hood.

I'd run a begi manifold. haha.

Of which? where there's a will, there's a way.

I like the way you think

log

1.5l i4
5.5 bar around 1300hp
almost 80psi


They also used different fuels than we do back than.

Interesting that you might want to do a Ramhorn setup. I will be talking to you about that.

Argh yees, I meant you!

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).

Toluene, IIRC.

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.

nah if you want to lower the boost threshold on a big turbo, advance the intake cam 3-4 degrees.

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.

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

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.

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

See actual data.

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

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.

:facepalm: Your link compares an equal length long runner bottom mount ramhorn to an extremely crude log (on a VTEC honda motor).

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.

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.

Passion you have. Logic you lack.

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:giggle:) 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

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.http://www.boostedmiata.com/gallery2...+collector.jpg

2. http://www.boostedmiata.com/gallery2...+collector.jpg

3. http://www.boostedmiata.com/gallery2...+collector.jpg

4. http://www.boostedmiata.com/gallery2...+collector.jpg

We also have Abe's ramhorn as follows.
5. http://www.boostedmiata.com/gallery2...hornartech.jpg

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.

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 :ohnoes:

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?

Yeah I did it "quick" after work tonight, before dinner. At the moment no they aren't all equal but each pair is (relatively). I plan to tweak it som-mo, try bringing #3 (the shortest) over #1, #2 is easy to lengthen.

All of these shown place the turbo in the same spot as my current centered/low mount manifold, including the twinscroll (but the twinscroll has the T4 flange). Anyway, back to the discussion :)

What runner length are you aiming for with the designs?

What I'd be looking for is equal length above all else, and the longest runners that can package.

Edit: And... looking for AC compatability. No PS though. Hard mode!

Equal length + long runner + A/C = essentially impossible.

I know. Really iffy on giving that up though.

A/C P/S? Bla. With enough time...

TS silly!
http://www.inoneear.com/outtheother/...0collector.jpg
Time for bed.

No, no need for P/S.

AC and PS and long tubes!?

http://gallery.y8s.com/d/22198-2/waterlines03.jpg

shit son, I been doin that so long it's been discontinued.

(dont think they are equal length tho)

Yeah.... that's... not what I'm looking for. x.x

Who made that manifold? And is it y8s like Yeats or y8s like yates or y8s like yatts (e.g., Matt).

Attachment 191255

If the last tubes had a nice U in them and the turbo was sitting lower and futher back, I could see a longer tube header working fine with AC. Certainly not in the low mount spot of the Absurdflow setup, but doable.

It's a greddy, and obviously not perfect, but just as an idea. Moved a bit further down and further forward, actually... lots forward without PS would be possible.

Fluid dynamics favors a design with the fewest bends from a drag and loss of impulse energy standpoint. You want very few 90s and no 180s if you want to maximize the effect of energy pulses on the turbine and not slamming into a corner and being dissipated as heat or rebounding. I don't have access to the fluid dynamics programs that some of you were using for intake manifold design, but many of the same principles are applicable. I recall that each 90 creates as much drag as 20 feet of straight pipe of the same diameter. If you must bend, use wide sweeping arcs.

you could just make an absurdflow absurd mount and put the collector above the left front wheel

Hmm...ok, makes sense. How about this one then? ;)
http://www.absurdflow.com/miata/stan...absurdflow.jpg

true. Or in front of the engine sideways like some drag cars do. Anything's possible.

Here is whats on my car.
1-1/4” schedule 40 pipe from head flange to turbo flange the equal lenght runners are 16.6” long
Note the Dyno-plot. Heavy on low and mid rage torque spools a GT3071R quickly not a top end only shape at all.

Definately not AC/PS compatable.

Bob

Very nice! It is weird that when I look at your .jpg's I instinctively try to rotate them to get a different view? haha. What software was that modeled in?

ProE

Things to note the turbo is shifted forward and is mounted very low. If it was centered between the 4 runners the outlet of the compressor would be pointing right at the steering shaft U-joint and wouldnt fit well.

Bob

What size A/R on the 3017 bbundy and who made the manifold?

Also Tim could you possibly replicate that thing. That low end torque is godly. Beat my t2554 by a metric shitton.

Turbine
-Wheel: 56.5mm w/ 84 trim
-Housing: 0.64 a/r

Compressor
-Wheel: 71mm w/ 56 trim
-Housing: .50 a/r

Internally wastegated.

I made the manifold myself. It’s lasted almost a year without messing with it now that I switched to Inconel studs. I made it before there were V-bands available.

Bob

Note that his engine is a stroker. Kinda like comparing apples to apples dipped in cocaine.

He is running on a bone stock 1.8 right now iirc and has been for about a year.