180 Degree Headers

[michalym]

I've been lurking on the site for quite a while now. Time to come out of the shadows.

I'm building a red LS7 powered GTR in Ottawa, Ontario, Canada (FIA cage, rose joint suspension, G5050, Kinsler FI). I've had the good fortune to be able to visit with several Ultima builders to gather ideas and pointers. One feature in particular that stuck with me is the 180 degree exhaust system on Chris Julian's car. Chis has done an awesome job on his build, and the sound of his exhaust system is amazing. While I understand that the unavoidable length of primary tubes will compromise some peak HP, I am prepared to make that trade off to get the distinctive exhaust note.

Chris pointed me to the Riley website where they feature their new track car. If you look closely at the pictures they have posted, and review their promotional video, you will see (and hear) that they are also running a 180 degree headers. I spoke to Bob Riley and he provided me the name of the outfit that built their system (Pro Fabrication in North Carolina http://profabrication.com/ - you can see another picture of these headers at the top of their home page). Steve at Pro Fabrication was very helpful. He confirmed from a few pictures that I sent him that while the engine bay of the Riley track car is similar to the Ultima are not close enough to consider trying to adapt the existing Riley headers.

Getting my chassis to North Carolina is not an option, but Pro Fabrication can work from CAD models. So I am reaching out to try to find two things: (1) a CAD model of the GTR (FIA cage) chassis fitted with an LS7 (maybe I'm dreaming here); and (2) any other owners who may be interested in a group buy (in which case a CAD model of their standard GTR and/or Can Am would be helpful).

I'm looking forward to hearing from anyone who might be able to help out, and from anyone who might be interested in considering the same path in a group buy. I would also be interested in any other opinions on 180 degree exhaust systems.

[02PRUV]

This might be a stupid question but is the only reason you want to do this for the noise? Just seems a bit strange to go to a lot of money and effort for a possible loss in HP and a gain in weight. Just seems like something a Honda owner would do not an Ultima owner?

Edited by 02PRUV on Monday 27th December 00:04

[cymtriks]

I can't see why you'd lose power with a 180 degree header, they were originally used to get the most power possible out of a conventional cross plane V8.

A close second to the 180 degree system is the 270 degree 4-2-1 system in which you have cylinders A/B and C/D paired on one side and cylinders A/C and B/D paired on the other side. (I've avoided numbering cylinders as there are several different conventions around) The pairs then combine again to complete the 4-2-1 arrangement on each side. This system can,apparently, get very close to a 180 system.

[V8Dom]

Im also looking at 180 headers on my sbc..


I think it might be myth that they gain horsepower as they all tried it in the 60's and 70's but they do sound great I must admit..

My primaries will be within 1/2 of each other and as close the wave length as possible

Dom

[cymtriks]

V8Dom said:

Im also looking at 180 headers on my sbc..


I think it might be myth that they gain horsepower as they all tried it in the 60's and 70's but they do sound great I must admit..

My primaries will be within 1/2 of each other and as close the wave length as possible

Dom

They all tried it after testing by Ford for Ford's racing cars. If it had been a dud idea it wouldn't have been used.

Marquis Rex (who works for Jaguar and worked on all the Jaguar engines) once stated that a 180 degree system (either flat plane or cross plane IIRC) was best with the 270 degree system being a much more practical arrangement and very close second in terms of power.

[michalym]

Here's an article that provide some background on why 180 degree systems were used and what their shortcomings are in modern racing engines (length of primaries).

http://www.burnsstainless.com/bundleofsnakes-2.asp...

[cymtriks]

michalym said:

Here's an article that provide some background on why 180 degree systems were used and what their shortcomings are in modern racing engines (length of primaries).

http://www.burnsstainless.com/bundleofsnakes-2.asp...

That article suggests that a 180 system could work well if the pipes were shorter than the historical GT40 set up and also suggests that running the pipes under the sump would make a 180 system work well on a modern higher reving engine.

IIRC Marquis Rex mentioned running the pipes under the sump but went on to state that a 270 degree 4-2-1 system would be close with far easier packaging.

[k wright]

The logic that was in place when this system was devised for racing motors holds true today for street/track day motors.


RARELY will a large V8 see more than 7000 rpm at any venue. I say go for it and make sure that you have cad files that make the system reproducible.

Thanks for the link to Burns Stainless site.

[GTWayne]

These type of headers are used on Ford V8'S, not Chevys', the firing order is different.
When building the GTW I too looked at every permutation ever mentioned and found Dave Vizard to speak total sense based on actual research and real world use. He tried 180 degree type headers and found them to be of no significant improvement on the SBC motor.

[P15TON]

A lot of things were done many years ago because it seemed like a good idea, the theory was worth a try, and that people didn't really know how things worked.
Now they do know how things work, and where ever there is a big enough budget & clever enough people, you will never, ever see a 180 degree system.
The optimum V8 system is a 4:1 of the correct diameter & length, or a 4:2:1 with similar criteria.
The lengths & dimensions depend on intake runner length, power output & peak power rpm, which is again related to port cross sectional area, and size of the exhaust valve.
Basically, there is no system dimension that's 'right' for all engines.

[V8Dom]

P15TON said:

A lot of things were done many years ago because it seemed like a good idea, the theory was worth a try, and that people didn't really know how things worked.
Now they do know how things work, and where ever there is a big enough budget & clever enough people, you will never, ever see a 180 degree system.
The optimum V8 system is a 4:1 of the correct diameter & length, or a 4:2:1 with similar criteria.
The lengths & dimensions depend on intake runner length, power output & peak power rpm, which is again related to port cross sectional area, and size of the exhaust valve.
Basically, there is no system dimension that's 'right' for all engines.

so which one of the mainy formulars is the best one to work the pipe size and length out then>

[P15TON]

We have our own

[spatz]

gladly we have enough power from the LS engines so we can loose some horsepowers in the exhaust system, so your "own" formula will not generate any revenue with me.........my advice if you wanna sell something it is not enough to say we are better you have to proove it, silly me that I am so persistent.

[GTRCLIVE]

spatz said:

gladly we have enough power from the LS engines so we can loose some horsepowers in the exhaust system, so your "own" formula will not generate any revenue with me.........my advice if you wanna sell something it is not enough to say we are better you have to proove it, silly me that I am so persistent.

I don't think Pete Sells Exhaust systems last time I looked, but he will know what you need if hew builds your engine for you.... but then again you could always the KFC Colonel Sanders what he secret mix is .... good luck

Edited by GTRCLIVE on Tuesday 4th January 15:54

[Slow M]

V8Dom said:

so which one of the mainy formulars is the best one to work the pipe size and length out then>

Actually, there's a gent who was kind enough to develop software with all of the appropriate formulae already in it. Pipemax is very easy to use, and has a great reputation for producing results that are usable in the real world.

B.

P.S. I just noticed that he hasn't developed a version for Win7, yet.

[spatz]

interesting pictures there, however I understand and correct me if I am wrong that exhaust gases only can enter the intake if the cam opens the intake valve while the exhaust valve is still open ? Is this what you say if you are referring to a hot cam ? I would assume a stock LS7 cam is not doing this ?
The conclusion would be that header design becomes really important if you have a very hot cam ?

thanks

[harry b]

spatz said:

interesting pictures there, however I understand and correct me if I am wrong that exhaust gases only can enter the intake if the cam opens the intake valve while the exhaust valve is still open ? Is this what you say if you are referring to a hot cam ? I would assume a stock LS7 cam is not doing this ?
The conclusion would be that header design becomes really important if you have a very hot cam ?

thanks

EVERY engine has overlap, even diesel. Without spooling it wouldn't work. The hotter the cam the higher the torquebandwidth. To keep it simple, small overlap, more lowend torque, big overlap highendtorque.
just REMEMBER, KEEPING IT SIMPLE!!
And proper header design is only usefull with the matching inlet design. It can make a huge difference in performance, and how it delivers.

[Gulf LS3]

We have tested several Ultima header systems on the dyno, standard crate headers, ultima supplied headers and our own design and they do differ greatly. With different effects on the 'in head' temperatures!

The biggest problem is space!!! You could optimise the setup but we simply do not have the space to do so, you have to compromise on the exhausts there is no way round it but if anyone wants to PM me i can pass on my findings. P1ston you told SS to make up 2" headers then backtracked and told him it should have been 1 3/4 so do you really have a formula? 1 3/4 will never be the best on a big 427 cu in motor!!

[spatz]

harry b said:

And proper header design is only usefull with the matching inlet design. It can make a huge difference in performance, and how it delivers.

ok are you referring to resonance intake systems ? Seems like tuning an engine is a lot about flow design.......

[harry b]

spatz said:

harry b said:

And proper header design is only usefull with the matching inlet design. It can make a huge difference in performance, and how it delivers.

ok are you referring to resonance intake systems ? Seems like tuning an engine is a lot about flow design.......

It is all about fluiddynamic, thermodynamic and wavedynamics. Calcululation models differ between wave action and filling-emptyiing models to make simulations.

LS3; For the standard 350 engine 1 3/4" came always out on top of my simulations. Bigger engines will probably go towards the 2". One thing often forgotten is the use of headermaterial. Stainless steel ain't ideal in thermodynamics pov, because they tend to store a lot of heat which creates more turbulance inside headertube, hence reducing effective diameter. This can very well be the 1/4"difference. Best option is to go for inconel625 material for headers, better heatresistance, faster heattransfer, much lighter to build. Bit expensive though.
The above only works for NA engines, in any turbo application you want to keep as much energy (heat) up until the turbine.