vrex

I understand the concept of why its benificial to use a twin scroll manifold design (everything similiar to stock) for its quick spool characteristics. its theoretically ideal to have the shortest length runners possible with turbo cars to preserve exhaust pulse energy. long runner, equal length is great for N/A cars, where one would tune for the exhaust waves to create vacuums to pull the exhaust coming out of the next cylinder in the firing order more effeciently. which is why i dont understand the huge manifolds AMS makes, but they get the job done. so what is the theory a company like burns has for specing slowwhiteevo a manifold like what he has, or the design AMS came up with? is it a combination of exhaust wave scavenging, then slamming it all onto the turbine? i read Jay Kavanaugh's article regarding design, and it doesnt seem to coincide with what Burn's has specd... (http://www.tantrumwerks.com/html/Spl...t%20theory.pdf)

so what is it im missing? what is the fundamental, or underlying theory, that Burns works off of in order to have arrived at an exhaust manifold that looks like that? they have a well earned reputation. but in this case, im not sure what they were thinking. anyone have some articles on fluid dynamics, or some info they care to post up and hypothesize what Burns was getting at?

if you havent seen slowwhiteevo's set up, check it out at
https://www.evolutionm.net/forums/sh...d.php?t=187969

Ted B

iTrader: (6)

Neither am I. Kavanaugh's article is correct. Also, have a look at the air filter on the car in question. . .

vrex

haha rockin the mesh screen alright well guess somethings gotta sacrifice if your gonna rock a manifold like that

vrex

nobody knows whats goin on?

Ludikraut

iTrader: (17)

Full-race's manifold is also no different (e.g. long runners) and it is also generating some very good numbers. IIRC, full-race uses CFD to help design their stuff. AMS does lots of dyno testing before they release a product.

l8r)

KOEvo

iTrader: (5)

That is the craziest manifold i have ever seen in my life.

vrex

so then its fair to speculate that Burns used CFD to arrive at that design... but why 4 equal length runners merging into a collector which leads to the turbo...i mean so much excess piping... is there a benefit that having the extra pipe after the merge collector adds to the system?

Ludikraut

iTrader: (17)

clarification: I meant to imply that the full-race header has similar length runners to the AMS manifold.

Neither is as extreme as slowwhiteevo's set up. I have no idea what the idea was behind slowwhiteevo's setup. It runs counter to what you would really want to do, especially considering weight distribution and cooling.

l8r)

mdsevo06

iTrader: (41)

The TQ seems very low, I'm assuming it's due to the Tube Dia. and length. I wonder how long that Turbo will last with no filter, might be a nice warm place for bugs to sleep in.

tkklemann

iTrader: (6)

That is quite an interesting setup, especially after reading the article, then looking at his set-up. Also interesting of the added support bar to hold the turbo in place as well.

I took fluid dynamics and hydraulics and pneumatics (Similar) while in school at Rochester Institute of Technology as a Mechanical Engineer, and I would think that the manifold in questions would increase the spool time on the turbo just because of how long it it, and how the exhaust gasses would loose velocity being so far way from the turbine housing. But, then again, maybe it works, maybe it doesn't. Sure is a neet looking set-up though.

I would think that with all my schooling I have been through, your perfect turbo set-up would be where the primary lengths are as absolutely short as possible, so you have little to no velocity loss. My buddy has an STS rear mount tubo kit in his Camaro, and the spool takes a long time, but happens so smooth and gradual as compared to my Evo. Then again, what I think would be right isn't always the case. Maybe they did enough testing to validate it (The design)?

Ted B

iTrader: (6)

Perhaps the length is to allow the low-angle merge into the collector without creating bends of too short a radius.


Bingo.

Heat is free energy. Lose heat, lose energy, reduce exhaust gas velocity, get less energy through the turbine, increase spool time. Furthermore, there are remarks made in that thread about greater heat dissipation, which is exactly what one does NOT want in an exhaust manifold. The ideal exhaust manifold is one that works like a big heat sink - soaks a lot of exhaust heat while radiating very little.

mdsevo06

iTrader: (41)

With that STS Rear Mounted Kit, you do lose velocity and spool takes a little longer, but in some cases you don't have to add a Intercooler.

trinydex

iTrader: (12)

that setup is most likely due to space restrictions of running a huge turbo, you'll notice that br's huge turbo car has a small radiator and love fab routes the turbo over in that same area but does so from underneath, apparently trinababe found a picture of a cosworth header that was piped much the same way.

when it comes to these types of applications i think the benefits of running a huger turbo outweigh the defecits inccured by a less than ideal piping setup.

also, piping setups particularly regarding top end power machines are a bit less critical. because you're aiming for a smaller area (rpm range) of best performance. it's hard to make a street header because you need (debateably should) the top end power and the low end grunt. for high rpm only, if they can sort the scavenging to a fair degree then they'll get it.

a longer runner gives more time for the low rpm pulses to scavenge but will also reduce the scavenging power because it's distributed over more volume but at high rpm this get better and better. longer runners also reduce the chances for inversions.

to point out where that manifold really sucks *** (by all around performance standards) you can see how they introduce an expansion in the final runner (btw this is not known as 4-1, 4-1 is what we have in most evos... the collector is the final junction, i would call this a 4-1-1). but to give this part some qualifying, you DO reduce the chances of reversion a LOT with a 4-1-1 design because the collector is not placed where the maximum back pressure is. also i bet this setup works very well with a non divided t3 flanged turbo. but yes... definitely made for peak power as that final runner will ruin all your chances for low end torque.

TrinaBabe

iTrader: (3)

That design looks pretty and that is about it I would guess.

I agree that the longer runners are primarily designed to make huge turbos fit. That turbo in the pics is not a huge turbo at all, they made it so the air filter can not fit, etc... Not a good design. On top of that, it seems that that design gives a ton of room for hot air to soak the underhood temps. Most of the time when people design very long headers they also try to squish the turbo somewhere in a cold intake zone (Facing the inlet forwards through the grill, etc..). This one doesn't even do that.

If you really wanted to run out the math on the design of a header you could make it a tuned header which in theory should increase the velocity of each pulse through scavenging.

Scavenging is pretty much creating a low pressure zone just in front of the exhaust pulse for each event which should help pull the exhaust pulse along. Do I really think this header (Or any for our cars) is designed with scavenging in mind? Probably not for the simple idea that scavenging probably wouldn't work too well considering you are creating a high pressure area right in front of the turbo which I would guess would negate the scavenging effect anyways.

From what most people say, you want the highest velocity and the most heat to enter the turbine. The velocity obviously helps spin the wheel and the heats expansion supposedly will help spin it also. The longer the runner, the less heat and less velocity. But you also need to remember sooner or later all that exhaust gas will leave the car. It just takes more HP to push the exhaust out because the backpressure would be greater. In these cases thier turbos are big enough where it doesn't matter so all they are loosing is spool and some HP. On top of that, by facing turbos in a cold air zone you may make up some of that HP by shoving enough air into the turbo.

NoisyTurbo

Thats a fine looking set up!