180 Degree headers on a VH45DE.

[elwesso]

I was reading my copy grassroots magazine... They had this section where they compete building cars that only cost like $2000 to build or whatever, thats not the important part.

Anyway, a guy swapped a chevy small block into a 260Z. One of the things that caught my attention is that he fabricated 180 degree headers for the motor.

If you dont know what 180 degree headers are, instead of all 4 of one side going to a collector, the cylinders taht are 180 degrees apart in their firing are paired together, maximizing scavenging, the bad part is its a nightmare to plumb it. I guess it would be while one is on the compression stroke, the other is on the exhaust stroke so that theres a constant flow, helping to smooth out the pulses.

I guess I'd just like to bring this topic up and see what others would think. Id think on a high revving motor like the VH45 this might really help high end power.

I guess the question would be is which cylindres you'd have to pair together, i guess someone with a VH crank would be able to tell which ones are 180* apart.

BTW, heres a thread about this on another forum i found

http://www.ffcobra.com/cgi-bin...3;p=0

[SSDwellah]

Actually the crank alone doesn't really tell you anything -- a piston at the top of the bore can either be:

1. At the end of the exhaust stroke/just before intake stroke.2. At the end of the compression stroke/just before the combustion stroke3. In some illegal stroke (someone indexed the camshafts wrong with respect to the crank).

The easiest way is just find the firing order, which should be in the FSM. Then, since the VH is a four stroke engine, there are 720 degrees per cycle, and thus 720 / 8 cyl = 90 degrees between cylinder firing events. Thus you pair 1st and 3rd in the list, 2nd and 4th in the list, etc...For example:

I think the VH45DE has firing order 1-8-7-3-6-5-4-2Therefore an obvious pairing is:1,78,36,45,2

NOTE: there are many other pairings that are 180 degrees apart, e.g.2,8 (wrapping around the list)4,1, (wrapping around the list)...

I think the goal is to pick them so they are all on the same side (cylinder bank) and the plumbing is not so bad. Then I guess it is a standard 4-2-1 header on each side.

I don't know the way nissan numbers the cylinders on the V8's so I'm sorry I am being kind of abstract and theoretical rather than concrete and specific.

YMMV

[evildky]

Thats Andy Nelson's car, it was simply amazing, ran I believe 10.52 in the quarter and sounded unlike any v8 I've ever heard. It sounded mroe like a Ferarri than a SBC. I was supposed to drive it for the autocross but he had Guido and the pro's drive it instead ( he didn't evne watch the autocross portion). I believe all the individual runners hit the single 4 inch collector at the same point but in sequence, the piping wrapped all around and under the car, and the giant hump in the floor to make room for the giant exhaust to run back. If you want to know more about it I can emial Andy and see if he'll come explain it.

[elwesso]

When i saw the pictures it definitely looked like a handful of snakes. I dont know if its feasible to put headers like that on a stockish Q45 or other swaps, but it would be pretty cool. It looked like a total mess of plumbing...

Do you know what kind of mods he had to do in the Z to make it work? Like, anything hardcore (firewall/frame cutting) or what? I'd love to hear a clip of an engine with 180* headers...

I'm going to have to dig that magazine back up.

Thanks for the explination Jamie. I didnt realize it was that simple.. I would think that you would want the pipes to merge as quickly as possible to maximize the venturi effect. I would also think that in tight engine compartments it may not be as good as regular headers if you have to route pipes all over the place

[T45]

http://www.youtube.com/watch?v=zQx98IhxS6E

[doctorchee]

hi

i am setting up my exhaust now also..180degree deisgn too..i posted it some where 2weeks back.. there was no response. however, glad someone is looking into it to discuss.

my application is for twin turbo.. i do not know if its help, but i will do it. as my exhaust shop i believe they will start work today and properly finish it in 1 month time...

here is the link to my mesage...the last second post should have more info on what i am thinkinghttp://forums.nicoclub.com/zer...age=3

cyclinder number (not correct, just use it as sample to explain design) 1 5 2 6 3 7 4 8

4-2-1 header design -set 14 - 1,4,6,72 - 1+4, 6+71 into turbo 1

4-2-1 header design - set 24 - 2,3,5,82 - 2+3, 5+81 into turbo 2

here is a brief photo of how i like to pair them..http://i177.photobucket.com/al...7.jpgh ... al...0.jpg

so here is my questions: 1) what is the firing order of VH41? same as VH45? 1-8-7-3-6-5-4-2 ?2) what is the cyclinder numbering? 3) is my pairing correct anot?4) for twin turbo, should i x the pipe after exit from turbo? or should i have individual exhaust after the turbo?

please advise and comments... need help asap as my exhaust shop is doing the flange now... they will begin very soon..

material in stainless steel...

thanks...

Derrick


Modified by doctorchee at 3:52 AM 8/27/2007

[mtcookson]

Heh... what a coincidence. I have actually been planning on doing this for quite a while (a big reason why I got the dry sump, but I've been keeping it under wraps... guess I should have mentioned it ).

To do a 180 degree header setup on a standard V8 (90 degree crank) you will have to have 2 pipes from each side of the engine cross over to the other side. It will sound like a Ferrari engine too. Why? The Ferrari engines use flat plane cranks so they essentially run like two four cylinders in the same engine which means if you connect all of the cylinders of bank to each other and do the same on the other side they'll automatically be separated by 180 degrees as a flat plane V8 fires L-R-L-R-L-R-L-R (that's left and right) (basically, you're getting even pulses of the exhaust through the exhaust system).

The exhaust pulses of our VH's with its firing order of 1-8-7-3-6-5-4-2 are like so:

R-L-R-R - L-R-L-L (R=right, L=left, these are the banks)

Notice two cylinders from the same bank fire right after the other, this is why the cylinders must crossover to have 180 degree separation.

This is the cylinder location:

F/R 1-3-5-7 back/right/passengerF/L 2-4-6-8 back/left/driver

An easy way to see how to separate them by 180 degrees is to put the first 4 firing over the last four like so:

1-8-7-36-5-4-2

1 and 6 connect, 8 and 5 connect, 7 and 4 connect, and finally 3 and 2 connect. This gives you the 180 degree ignition separation. Still confused? Here's a visual of how it works. Say the VH had a distributor, it would hit the contacts of each cylinder like this:



Notice the points that are exactly 180 degrees apart from firing... this gets the connecting cylinders listed above.

That's my basic understanding of it all. I've been looking into it for a while but some of it still confuses me.

[SSDwellah]

Some how this seems a bit off. With all due respect I think you are not taking into account that in a 4-stroke (aka Otto Cycle), there are 720 degrees between firing events on the same cylinder. Thus 1 and 7 are 180 degrees apart, not 90 like in your circular diagram -- you really need two circles that overlap, one is phase 1 (0<=360 degrees), the other is phase 2 (360<=720 degrees).

Forgive me if I am wrong, but your example just doesn't look right to me.

[mtcookson]

You are correct that 1 and 7 are 180 degrees apart, but that is at the crank. My picture is depicting a distributor (if the VH were to have one) where 1 and 7 would be 90 degrees apart in the distributor.

In my picture, cylinder 1 fires and 180 distributor degrees later 6 fires (this is 360 degrees of crank rotation). I'm pretty sure this is what they aim for to get the 180 degree separation.

I'm not sure if I can explain it very well but here's another thing that makes a bit more sense to me, you made note that with the numbers you had there are other pairings of numbers... if you take my example you will never have any other pairings, which makes much more sense to me.

Also, the bigger thing that makes me think its right is I'm basing it off of this site: http://www.rocky-road.com/thorley.html

I don't know if that site is correct either, but I've thought through the different scenarios and this one definitely makes the most sense to me.

[Mettler]

It all seems like a lot of effort for minimal gain... you can use an X or H pipe just after your headers to equalise pressure across both manifolds... I realise it's not the same thing though.

What realistic gains do you guys hope to see with such a setup? Good luck with your fabrication nightmare! :p You'll have to be damn good to get all the runners equal length and to have smooth bends!!

[SSDwellah]

You are correct that 1 and 7 are 180 degrees apart, but that is at the crank. My picture is depicting a distributor (if the VH were to have one) where 1 and 7 would be 90 degrees apart in the distributor.

In my picture, cylinder 1 fires and 180 distributor degrees later 6 fires (this is 360 degrees of crank rotation). I'm pretty sure this is what they aim for to get the 180 degree separation.

I'm not sure if I can explain it very well but here's another thing that makes a bit more sense to me, you made note that with the numbers you had there are other pairings of numbers... if you take my example you will never have any other pairings, which makes much more sense to me.

Also, the bigger thing that makes me think its right is I'm basing it off of this site: http://www.rocky-road.com/thorley.html

I don't know if that site is correct either, but I've thought through the different scenarios and this one definitely makes the most sense to me.

Okay you edited your post a little bit since I last read it. At least the graphics is a little bit different. Rememebr that the distributor runs at half the angular speed of the crank due to the fact that it is mapping an actual 720 degrees of crank rotation to 360 degrees of rotor rotation (i.e. when the "clock" goess from 12 to 12, the crank has really travelled 720 degrees).

Anyway, here is another link about this topic:http://home.alltel.net/bsprowl...s.htm

I am not 100% sure and I have said my $0.02 so I will defer to the experts

[David Steele]

I remember some ******* flamed me when I spoke of pulse converter manifolds for a twin scroll turbine housing.

8-4-2-1 manifold going off a 90* firing order.

I can only see this happening for people who move there engine back in there engine bays.

[doctorchee]

I remember some ******* flamed me when I spoke of pulse converter manifolds for a twin scroll turbine housing.

8-4-2-1 manifold going off a 90* firing order.

I can only see this happening for people who move there engine back in there engine bays.

i have my engine moved back long time ago..... very back...... .

[doctorchee]

It all seems like a lot of effort for minimal gain... you can use an X or H pipe just after your headers to equalise pressure across both manifolds... I realise it's not the same thing though.

What realistic gains do you guys hope to see with such a setup? Good luck with your fabrication nightmare! :p You'll have to be damn good to get all the runners equal length and to have smooth bends!!

i guess:some hp? not muchmore linear torque? a little more torque also?a high pitch ferrari exhuast sound? (this is what i like most..)others??? not too sure...

[mtcookson]

I remember some ******* flamed me when I spoke of pulse converter manifolds for a twin scroll turbine housing.

Yeah, that's kind of crap. The pulsed manifolds are definitely proven to be much, much better than constant pressure when it comes to a turbo. If you can do them, they're most definitely the way to go.

Okay you edited your post a little bit since I last read it. At least the graphics is a little bit different. Rememebr that the distributor runs at half the angular speed of the crank due to the fact that it is mapping an actual 720 degrees of crank rotation to 360 degrees of rotor rotation (i.e. when the "clock" goess from 12 to 12, the crank has really travelled 720 degrees).

Anyway, here is another link about this topic:http://home.alltel.net/bsprowl...s.htm

I am not 100% sure and I have said my $0.02 so I will defer to the experts

Yeah, I added a few lines and changed the colors to make it a little more understandable. Other than that its the same picture.

After reading that site you posted... I think the biggest problem here is that the term used for these headers is used poorly. If they would call them 360 degree headers there wouldn't be confusion and if they were called 180 degree headers with some sort of good reference to ignition it would be a little less confusing. I think I'm going to call them 360 headers from now on, that'll be less confusing for sure.

[elwesso]

I wonder if the pulsed setup might be good on a low mount turbo (sorta like a quasi-rear mount). Thinking like an 8-4-2-1 into a single turbo? Maybe a bi-turbo setup, I dont see making twins that way anywhere short of a nightmare unless its like in a sand buggy or something that isnt limited to room.

[mtcookson]

That would be something interesting to find out... I'm not sure which would be more efficient in the end. Just depends just how far back the turbo has to be to make it fit. Very far and a standard setup could be potentially more efficient.

[T45]

I have to go with Mettler on this one and say that the work involved outweighs the benefit. If you put a VH in a sandrail or something then it would be easy. In a car it's just silly.

[David Steele]

I have to go with Mettler on this one and say that the work involved outweighs the benefit. If you put a VH in a sandrail or something then it would be easy. In a car it's just silly.

Actually in a twin scroll turbine where 180 separation is required it's not dimensionally insane because :

180* Separation perfectly Bank 1 1-7/3-5 - Bank 2 8-2/4-6 .

Very much possible sir for a single turbo configuration using V-band to joint the two tubes together. That'd be the 4-2-1 .

[elwesso]

Actually in a twin scroll turbine where 180 separation is required it's not dimensionally insane because :

180* Separation perfectly Bank 1 1-7/3-5 - Bank 2 8-2/4-6 .

Very much possible sir for a single turbo configuration using V-band to joint the two tubes together. That'd be the 4-2-1 .

so all you have to do is pair 1-7, 3-5, 8-2, and 4-6? That doesnt seem like itd be any harder than making regular headers...

can someone confirm this information is correct? seems different than what others are saying.

[mtcookson]

That would probably be better than a standard manifold joining all together but definitely won't get you the scavenging affect that the true "180" degree headers would give. Some cylinders would probably see a good vacuum and others wouldn't.

Technically those are set at 180 degrees of separation but on the crank, not ignition so to speak. The optimal would be where they are 180 degrees apart on the ignition cycle, which is 360 degrees apart on the crank.

If our engines had a flat plane crank you could keep the headers on the same sides but to pull it off with a 90 degree crank, you'll have to cross some pipes.

I'm now starting to believe that they likely did name these headers basing them on the distributor. Needs updated for the distributorless engines now.

[David Steele]

How is that not on ignition the low resolution sensor show 8 slits with 90 degree separation in the camshaft sensor. So thats 180 separation for the firing order, with the grouping I posted.

And for a twin scroll turbine this is exactly whats wanted.




Modified by David Steele at 8:58 AM 8/30/2007

[mtcookson]

With yours you are getting 180 degrees of ignition separation on the crank. Lets take 1 and 7. 1 fires then 180 crank degrees later 7 fires. Now... you have to 540 degrees for the exhaust pulse of cylinder 1.

I'm not 100% sure, but I think the what they mean when talking about 180 degree headers is solely with a distributor so to speak. Looking at crank alone... these headers are 360 degree separation headers, which will give you perfectly even exhaust pulses down both tubes.

The effect you're going for is this: Say 1 and 6 are connected, they're 360 crank degrees apart. When cylinder 1 is at top dead center of the compression stroke, cylinder 6 is at bottom dead center of it's power stroke getting ready to come up to push out the exhaust. Now... when it comes time for 6 to fire cylinder 1 is now going to be pushing the exhaust out on the 6's power stroke (after ignition).

When you tie these two cylinders together and get the length right and don't have any excessive restrictions, you can time the exhaust pulses to where when the exhaust leaves tube 1 it will actually put a vacuum on tube 6. You want this vacuum to be timed to when the exhaust valve of 6 starts to open and close. What happens is not only does this vacuum help to pull out more exhaust there is a slight period of overlap where the exhaust valve and intake valve is open at the same time. What happens is while that vacuum is pulling the exhaust out of the cylinder it is also pulling fresh air into the cylinder. This effect is called scavenging. This is how you get a normally aspirated engine to have a volumetric efficiency of 100% or even more, yes more. I know there are some race engine builders that actually like to call this the "5th cycle", where the exhaust pulls in air from the intake.

If you pair 1 and 7, the exhaust of cylinder 1 should put a vacuum on cylinder 7 causing the scavenging effect but 7 will not do the same for 1 as there is too much time between events.

Edit:

For the twin scroll housing the 360 degree crank separation headers are what gives you the even exhaust pulses for optimum flow and quick spool.

Also, the picture of the timing ring from the CAS is exactly what I needed to show what happens:

Here we go, so the timing ring's 90 degree marks are 90 degrees of crank rotation so this would be what is going on:



Notice that I flipped the numbers from the previous image. What is happening here is that the ring itself is moving, and if drawn right, will spin clockwise if looking at the engine front to back. So, what happens is cylinder 1 fires then 90 degrees of crank rotation later cylinder 8 fires, then 7, then 3, and so on. The 180 degrees of separation they are talking about is shown here, the timing event in the distributor or in our case the CAS. Notice cylinder 6 fires 180 CAS degrees after cylinder 1. This is 360 crank degrees and will make the exhaust pulses between cylinder 1 and 6 always evenly pulsed when joined together.

Now look at 1 and 7 for instance. 1 fires, then after 90 degrees of CAS rotation, or 180 degrees of crank rotation 7 fires. After that is 270 degrees of CAS rotation or 540 degrees of crank rotation before 1 fires again. That is where the problem occurs. You lose your effect of scavenging on cylinder 1.

[David Steele]

If you pair 1 and 7, the exhaust of cylinder 1 should put a vacuum on cylinder 7 causing the scavenging effect but 7 will not do the same for 1 as there is too much time between events.

There can be a vacuum on 1 the 1-7 group merges with #2 bank 6-4 on the VH and then 3-5 merges with 8-2 to get a low pressure signal

This sounds right to me mtcookson.

[mtcookson]

You got it. If doing a 4-1 that should work out quite well.

If you want to do a 4-2-1, couple 1-6, 2-3, 4-7, and 5-8. Then 1-6-7-4 and 2-3-5-8. Then have one absolutely mean sounding VH (that should make noticeably more power to boot).

I think we finally solved it!

When using a twin scroll turbine housing, if using twins, be sure to connect 1-6 on one side and 7-4 on the other. This should retain the scavenging effect and give even, alternating pulses through the housing.

[David Steele]

Cool now I get what you mean on Ignition separation. I was confused at first!

Thats definitely following a flat plane V8 and very beneficial for twin scroll turbo charging.

Found some pictures on how this could be done even on a front engined car.

[David Steele]

I found a sound clip and it doesn't sound like that small block ford with 180 on youtube this actually sounds like a flat plane V8.

http://www.revsearch.com/dynamometer/headers.html

sound clip here

http://www.revsearch.com/sounds/dodge450.wav

I just called ''Revsearch'' to confirm that the sound clip is indeed the engine pictured*


Modified by David Steele at 5:01 PM 8/30/2007

[David Steele]

Some more things I found on this...

http://www.ls1tech.com/forums/...unt=6

http://www.hotrodder.com/emarsh/

http://www.britishv8.org/MG/BobEnglish1.htm

http://www.howeracing.com/Exha...e.htm

Ok $100 to the first person to do it on there Vh45DE

[T45]

Sounds like a 4 banger to me. I am betting the Vh would sound better though. What kind of gain is expected with this setup? 5 or 10 hp?

[David Steele]

Sounds like a 4 banger to me. I am betting the Vh would sound better though. hp?

Thats what a Ferrari flat plane sounds like with there 180 degree spacing.Dohc engines sound alot smoother though. That was a rusty dodge engine!

Quote »What kind of gain is expected with this setup? 5 or 10 [/quote]This setup increases power & torque because it decreases turbo spool significantly. As for NA who knows? I'm not gonna be NA.
Modified by David Steele at 7:59 PM 8/30/2007