INLINE SIX EXHAUST HEADER

[maxeffort]

I need to design a header for an inline six. It's an IH 301 based engine,

Port layout is very similar to the GMC 302 L6

I was referred to this site because of the vast experience with older engines in land speed racers. Any help is GREATLY appreciated.

The head has 4 exhaust ports. 2 cylinders have their own port and then 2 cylinders share a port (4 cylinders, 2 ports)

What is the best way to design a header for this? (can any pulse tuning / scavenging be achieved/)

How do I make size calculations for this style head? (the Siamese ports have me puzzled)

379 cu in, ( 3.915 X 5.25) 4200 RPM maybe more, need good torque at 3000-3200 RPM, 1.5" exhaust valve

This is how one of these heads look.

I don't have a complete photo of a whole head on here, but I can take one if it helps.

the center ports that each service two cylinders are rectangular, the end ports that each service one cylinder are square.

[Cajun Kid]

Go to  www.salterracingengines.com    The guy is Brian Salter

He can help you.

Tell Him  Charles  sent you...

[Sumner]

...............Brian Salter.........

With a name like that he should be building LSR engines  ,

Sum

[maguromic]

If that head is like the GMC 302, the two outside ports will flow about 20% more than the two center ports.  There is a lot of variables to building a proper exhaust and more info is needed.  I.E. exhaust CFM, cam specs, induction system, etc. The exhaust will help make an engine or break an engine.  The two people I would ask is Joe Fontana http://www.fontana-automotive.com he has been racing in line 6's for a long time and has helped few GMC get in the two club.  The other one is Mike Kirby at Sisslls Automotive. He has forgotten more about inline engines than most of us who race them know. http://www.sissellsautomotive.com

[Freud]

In my opinion, J.D. Tone isn't exactly standing behind the door.

FREUD

[maxeffort]

If that head is like the GMC 302, the two outside ports will flow about 20% more than the two center ports.  There is a lot of variables to building a proper exhaust and more info is needed.  I.E. exhaust CFM, cam specs, induction system, etc. The exhaust will help make an engine or break an engine.  The two people I would ask is Joe Fontana http://www.fontana-automotive.com he has been racing in line 6's for a long time and has helped few GMC get in the two club.  The other one is Mike Kirby at Sisslls Automotive. He has forgotten more about inline engines than most of us who race them know. http://www.sissellsautomotive.com

Thank for the links and contact info (from everyone so far)

Some more details (this is a puller, my apologies for that)

CAM specs: 258/258, 204/204, 594"/594" lift w/1.65 rockers, 108°

12.5:1 static compression

Intake is fabricated. Rectangular plenum with 180° down runners. Carb is a variable venturi predator or a single 4 barrel.

Header exit is vertical

Head port flow

1.84" intake valve

Int flow #=
.100 56
.200 106
.300 160
.400 184
.500 202
.600 204

 Exh flow  1.5" valve, Peaked out at 135 @.600" 

Port flow was very smooth and stagnant. Not much turbulence at all, so this is good usable quality air.

We were valve size limited, by the time we had throats opened properly there was only .040" or so left on the short-side to water.

[RichFox]

Join the Rod Riders and ask Don Ferguson. He has the fastest GMC around and he, his dad and his granddad have plenty of flowbench and dyno time in on stock head GMCs. A cornbinder on the salt is weirder than a Packard IMHO.

[Cajun Kid]

Sum,, great point on my engine guys name SALTER  !!! 

As a matter of fact he wants to build motors for LSR cars... Mine was the first "purpose built class engine"  he has done for LSR. Mine is anr "E"  class,,, It was a lot of custom work to get a SBC to below  260.00 Cubic Inches,  But he did it and achieved  1.98 HP per Cu.In. as well... (oh and we got the record on the brakes...) The lil stroke does not have much low end torque, but man above 4,000 she hauls it hard down the track...

I am convinced that this motor in a better areo body style would contend for the E/CGALT  record.. on the SALT.

In the winter, I am in hopes of doing  Studebaker body that is (if my buddy, lets me buy the one he found) or if not at least a 2nd. Gen Camaro or Firebird..

My Vicky is Brick, but I am into the street rod and vintage look and dont think in the standind mile at Maxton, I am giving up much to the more areo classic body styles through 1981...but who knows...

Anyone need an Engine,let me know,,, I can hook you up with Brian..

Charles

[Sumner]

......................I am convinced that this motor in a better areo body style would contend for the E/CGALT  record.. on the SALT................

201 mph is pretty stout for an un-blown gas E motor, but I think you should go for it  ,

Sum

[Cajun Kid]

Sum,  I see you looked up the record, as I thought you might,, Yeah 201 is stout for an unblown E motor  but it has been done once,,, so it sure must be possible... I think I have the motor to do it,, I know I don't have the car to do it in however...

I friend of mine  found a 53 Stude.. Trying to talk him into parting with it.

I hear Art Morrison  can do a 53 Stude chassis ?  Who knows...


Charles

[Sumner]

................. friend of mine  found a 53 Stude.. Trying to talk him into parting with it..........

I'd let him keep it and look for something newer with a smaller frontal area.  Since you can go to '81 look around.  With the Stude (stock body) from our experience you will probably need 500 HP to run 200+ (at the rear wheels).

Welcome to the addiction,

Sum

[jimmy six]

Nice idea. Your calculations, in my opinion, for rpm appear to be what you can get for that size valve with 65+ cubic inches per hole. You did not give the firing order and I'm assuming GMC/Chev 1-5-3-6-2-4. This firing order gives unven pulses for the the intake if it's the same, meaning 3-4 are the only ones seeing the identical thing.  I can't see if there is a partial divider in the dual exhaust port which helps. 

You need to build the header for torque as you are not looking for much rpm. You need to put them in an order to allow them to help the exhaust suck out the another one. I have used both a single and a two header system and both worked well.

On the dual, the ouside pipes were 1-5/8" and the shared ports were 1-7/8" meeting at 29-30". Collector length varied.

The single collector (not really) giving me better torque #'s lower rpm and was better at the top for HP. It was designed @ Burns Stainless and is of the double merge design. The single outside ports are stepped 3 times and the shared ports are steped twice. The front set meet at 27 inches right next to the rear set which are mirror image and then those 2 merges into another double merge which goes into the megaphone. Initial length were determined by them and can be adjusted.

Mike Kirby made a comment about head flow on a stock head GMC at our last Inliners meeting at his shop. A very high compliment to this idea. He said when you are done doing all you can in the exhaust porting area you go and do what JD did on his roadster if you can afford it. I definately thanked him for his compliment.

If you choose to do a single there are 4-merge collectors available to build you can look them up on the net. I've tried to include 2 pictures of mine and I hope they come out. (first time)

Good luck with your project.......JD

[maxeffort]

JD this is just excellent stuff. I'm finally getting some direction with this information. I can't thank you enough.

Do you mind if I share your post and pictures on another advanced engine building forum where we have been discussing this project?

Thanks,
Keith

[jimmy six]

Feel free. They were only a "secret" till I opened the hood. Hey, I "cameup" with the idea when I saw a NASCAR upside down in a photo. The pictues are also on the GMC Truck site. Good Luck

[Glen]

And it sounds bitchen at over 200 mph.