tubular exhaust manifold: 4-1 vs 4-2-1

JST · Mar 1, 2015

Jakx1331 said:
Hay JST I explained that the 4-1 header is for higher RPM range

Ah ok, missed that part. We will see what happens.

Boyka said:
They look great!

Yeah, nothing wrong with the looks!

daniel. · Mar 3, 2015

@JST - The tubular manifold is on my car from the beginning... One log manifold can spool like my tubular, but in the high RPM range, the log manifol would be the worst scenario.. IMO

I assume you'll test the both manifolds on a 2056vk, correct?

JST · Mar 3, 2015

daniel. said:
@JST - The tubular manifold is on my car from the beginning... One log manifold can spool like my tubular, but in the high RPM range, the log manifol would be the worst scenario.. IMO

I assume you'll test the both manifolds on a 2056vk, correct?

I am convinced the tubular will be better for flow/ highend power.
The main question is what happens with the lowend. I wouldn't be suprised if that will be worse with the tubular.

I test both manifolds on a GTB2056v (factory vacuum operated). Wheel spec is the same as Volvo gtb2056vl.

ryanp · Mar 3, 2015

The difference low end from the extra volume would be so minimal IMO that the turbo vanes closing a touch more would overcome any 'lag' created by the manifold.

good merge is where the power is on these!

Jakx1331 · Mar 3, 2015

That's why I commented on this is to see which one would be better for bottom end power. im making a new off-road vehicles with another tdi.

JST · Mar 3, 2015

ryanp said:
The difference low end from the extra volume would be so minimal IMO that the turbo vanes closing a touch more would overcome any 'lag' created by the manifold.

good merge is where the power is on these!

Thanks for that comment Ryan, that makes sense.
I am convinced the merge collector is properly made, I'll upload some more detailed photos when I receive it.

Jakx1331 · Mar 11, 2015

Hay JST have you got any photos and/or dinos yet?

Rub87 · Mar 11, 2015

ryanp said:
The difference low end from the extra volume would be so minimal IMO that the turbo vanes closing a touch more would overcome any 'lag' created by the manifold.

good merge is where the power is on these!

Actually thats not really the case I think, at the very ends of the vane position turbine efficiency is tapering off steep. Manifold volume acts like a spring, not a perfect spring unfortuately so its more like a spring/damper in reality, its like you're running in loose sand on a beach.

The merge angle is just a part of the system. What counts is the pressure drop from port to turbine entry. Less is more (, and the same applies to volume). There is no reason a well designed and ported log manifold would perform worse than a tubular one. All state op the art production turbos cars have short very compact manifolds as an attempt to minimise energy losses. They're making over 200 hp per liter with peak torque available below 2000 rpm so without vgt turbines. No need to reinvent the wheel.

ryanp · Mar 12, 2015

I totally agree but designing, testing and making a cast log manifold would take more work and be more expensive than tubular!

Road cars we make them as short as possible with decent merge, race cars Long radius bends and a shallow merge angle, always seems to work.

shakescreek · Mar 13, 2015

So this thread has got me curious as to just how much volume difference there is between my 4into1 tubing manifold and a typical cast log manifold. So I just clamped a plate over the turbo flange on mine and filled it with water from a graduated flask. It took exactly 1060 cc of water to fill it flush to the top of the cylinder head flange. Anyone know the volume of their cast log manifold for comparison? Unfortunately I don't have a cast manifold here to measure.

andy2 · Mar 13, 2015

Having one of these manifolds was as good as it gets !

Low internal volume,Keeps heat in,Flows very well.I almost wish I had of bought one of these while they were still around.

I've ran over 400 BHP through the manifold pictured below,

Fiodor · Mar 14, 2015

This collector who according to you will be the best for the rpm of the upper and the lower rpm who?

andy2 · Mar 14, 2015

Fiodor are you asking me ? I'm only using the manifold in the bottom picture as I have no room for anything else.Its far from ideal however it does the job.The manifold in the top picture is far better for all rpm range.

shakescreek · Mar 14, 2015

Andy do you happen to have one of those not bolted to an engine, that you could easily measure the volume on?

JST · Mar 15, 2015

Jakx1331 said:
Hay JST have you got any photos and/or dinos yet?

Nope, the guy that makes the manifold is very busy atm, so it still needs to be finished.

shakescreek said:
So this thread has got me curious as to just how much volume difference there is between my 4into1 tubing manifold and a typical cast log manifold. So I just clamped a plate over the turbo flange on mine and filled it with water from a graduated flask. It took exactly 1060 cc of water to fill it flush to the top of the cylinder head flange. Anyone know the volume of their cast log manifold for comparison? Unfortunately I don't have a cast manifold here to measure.

Good point, my bet is the volume of a OEM manifold is less than half of a tubular. I'll measure it today.

b5converison · Mar 16, 2015

same has edc16 dynamic SOi .. but these are not easy to tune ..
so I have disabled mine ..

Rub87 said:
Delayed SOI and lower railpressure helps till a certain level. Edc17 has a function to delay soi based on rpm and boost governor error

JST · Mar 17, 2015

Just measured the volume of the OEM JTD manifold, it's about 570 cc.
This is how it looks:

shakescreek · Mar 17, 2015

That manifold looks like it should flow pretty decent. Seems you were pretty much spot on with your guess on the volume difference.

JST · Mar 18, 2015

shakescreek said:
That manifold looks like it should flow pretty decent. Seems you were pretty much spot on with your guess on the volume difference.

OEM design looks indeed not that bad. Areas of improvement are the merge section and outlet. The outlet is enlarged but still a few mm's smaller than the GTB turbine intake. Making it larger would make the wall thickness too thin for my liking.

Jakx1331 · Mar 18, 2015

I know equal length header tubes are nice for fuel economy and back presser on a gas motor it be nice to see if the ome are or not (by looking I say not). It also helps power nicely with equal lengths ( generally +10hp, +15 pownds of torque) over truck headers.

andy2 · Mar 19, 2015

shakescreek said:
Andy do you happen to have one of those not bolted to an engine, that you could easily measure the volume on?

I'll see If I can measure that for the log manifold.I'm using that manifold for high horsepower so volume isn't important.Keeping the heat in is the most important factor when comparing to a tubular manifold that "flowed well" in my opinion.Lost heat is just as bad or worse than having unnecessary volume I would think.

shakescreek · Mar 19, 2015

Makes sense. I wonder how stainless tubing with ceramic coating compares to cast for heat loss. Not very scientific, but just going by how much heat I feel radiating from the manifold when working close to it with the boat running, I would guess my ceramic coated tubing manifold loses less heat the the stock cast one did. I know stainless does conduct less heat than mild steel or cast iron, but the difference in wall thickness will affect it as well.

mbalmr · Mar 20, 2015

From manifolds I've had experience with a cast iron always holds in heat better than a tubular header. Ive seen headers coated and wrapped in an effort to keep heat in but its never as good as a cast iron version mostly due to the thickness of the material.

Sent from my iPhone using Tapatalk

Jakx1331 · Mar 29, 2015

Any word on the manifold yet JST?

JST · Apr 3, 2015

Yes, I just heared it is finally finished.
This is how it looks:

Jakx1331 · Apr 3, 2015

There pridy. Nice block hugers. When are you testing it and what are you going to teat other then hp, ft-tq, boost pressure?

JST · Apr 3, 2015

Jakx1331 said:
There pridy. Nice block hugers. When are you testing it and what are you going to teat other then hp, ft-tq, boost pressure?

Thanks.
I'll test it with datalogs in 4th gear.
First of all boost vs rpm to compare the spoolup. Then VNT% to see if it results in more turbine opening at same boostlevel (=less backpressure). Also EGT will be monitored.
And most important, i can compare acceleration times very precisely for every 500 rpm step. This works for me much better than dyno runs since the car struggles to reach the normal road airmass then, with reduced IQ as result. Driving and logging gives much more consistency.

Jakx1331 · Apr 3, 2015

Nice can't wait got a cr140 on the way from Canada with 1k on it for a new off-road rig

. I'm going to run with a biger turbo for the power level I want but don't want lag from it either

JST · Apr 5, 2015

Mergepart:

http://www.mijnalbum.nl/Foto1k0-NY3TZJ8I.jpg

Jakx1331 · Apr 5, 2015

Nice merge point, bankes power has a "power pickle" there to pervent exhaust turbulence. Less turbulence more flow, more power

tubular exhaust manifold: 4-1 vs 4-2-1

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