What is the advantage of Ford's SHO Split-Port intake manifold?
What is the advantage of Ford's SHO Split-Port intake manifold?
(OP)
As you can see in these pictures, Ford (with the help of Yamaha) produced this intake manifold where each cylinder has 2 intake runners of different length.
Engine info: 1989 to 1995 Ford SHO engine, 3.0L
What is the advantage? Do any other engines do this? Is there a valve enabling and disabling half of the runners? Is each runner routed to a single intake valve, and if so are the intake valves of same size, orientation, and function?


Thanks in advance!
Engine info: 1989 to 1995 Ford SHO engine, 3.0L
What is the advantage? Do any other engines do this? Is there a valve enabling and disabling half of the runners? Is each runner routed to a single intake valve, and if so are the intake valves of same size, orientation, and function?


Thanks in advance!





RE: What is the advantage of Ford's SHO Split-Port intake manifold?
There might be a butterfly in the branch of the plenums of the one you posted.
It gives you a fatter torque peak.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: What is the advantage of Ford's SHO Split-Port intake manifold?
Could someone confirm this?
RE: What is the advantage of Ford's SHO Split-Port intake manifold?
RE: What is the advantage of Ford's SHO Split-Port intake manifold?
Long runners favor low speed, and conversely, so having two switchable runners of different lengths gives you at least two torque peaks. ... and probably at least two torque valleys also, but if you put the peaks where you can use them and push the valleys to where it doesn't matter, you can gain a performance improvement over a simple manifold of fixed geometry.
BMW produced a fairly complicated scroll- style intake manifold that changed the effective length of the runners, continuously, by rotating a part of the manifold with an electric motor, theoretically allowing the engine to run at intake resonance, and hence best torque, over much of its rpm range.
Fancy intake manifolds are more common than ever before, but there are so many features contributing to the performance gains in modern engines that it may be difficult to separate out the gains associated with any one feature. ... and the guys who really know this stuff have substantial commercial incentive to reveal as little as possible, about anything.
Mike Halloran
Pembroke Pines, FL, USA
RE: What is the advantage of Ford's SHO Split-Port intake manifold?
The long runner may be tuned for some target range but I would guess the short one would be more for open unrestricted flow.
You could have some fun with long staggered runners though.
These are some super rough numbers just to throw a little theory on the wall.
With say one 18 in runner and one 24 in runner you could alternate between the two something like this.
24 in 4th harmonic 3000
18 in 4th harmonic 3600
24 in 3rd harmonic 4000
18 in 3rd harmonic 4700
24 in 2nd harmonic 5500
18 in 2nd harmonic 6600
Only trouble is switching between the two runners would be a nightmare which is why most systems like this only actuate one.
I have thought it would be fun to build some sort of telescoping manifold some time.
That is far better but also not as cheap or easy.
RE: What is the advantage of Ford's SHO Split-Port intake manifold?
For flamboyant intake systems with switchable air path lengths, take a look at some of the offerings from Ferrari in their V8 engines of recent years.
But the ubiquity of the turbocharger is killing off the art of intake system tuning now.
- Steve
RE: What is the advantage of Ford's SHO Split-Port intake manifold?
Here's a dyno graph comparing a log manifold with a BBM
http://i204.photobucket.com/albums/bb160/H2Micr0/M...
Careful study of the vacuum actuator reveals that at idle both pipes are used, and then above idle the long ones, and then at something over 3000 it reverts to the idle setting.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: What is the advantage of Ford's SHO Split-Port intake manifold?
"Schiefgehen will, was schiefgehen kann" - das Murphygesetz
RE: What is the advantage of Ford's SHO Split-Port intake manifold?
Drag racing champ in the 60s, through the 70s and 90s he competed in open wheel racing like CART, USAC, INdy RacingLeague, Indianapolis 500, and even dabbled in Formula 1 for a few years.
One of his last rides was at Indy in 96 ( he was 54) where he took the (stock block) Buick Menard Lola from last place to 7th overall. Various years turbo'd stock blocks were allowed up 55 inches of boost.
I believe one of his street cars of choice back then was a Porsche 911 Turbo (930). The controls available to broaden and smooth the power back then were a bit limited compared to today, as is described in this 2013 refresher road test -
http://www.caranddriver.com/reviews/1978-porsche-9... ,
Others are a bit more blunt -
" Legendary turbo lag and an associated reputation as the scariest handling Porsche 911 of all have made the 911 Turbo into a legend."
http://www.historicracer.com/driving-reports/911-t...
Not too surprising then Danny Ongais comment back then to one of the car mags was " nobody can drive those things fast ."
Compare that to the computer generated flat torque curve and resulting progressive power everybody enjoys today.
http://giantmaw.com/Photo%20Album/Image%20Library/...
Or, the hard hitting jump in power of a peaky piston port mx bike on page 52 here -
http://honda-elsinore.alp-sys.com/publications/mag...
The sharp throttle response of this bike would only add (significantly) to the feeling.
RE: What is the advantage of Ford's SHO Split-Port intake manifold?
http://www.speedhunters.com/wp-content/uploads/201...
http://www.performanceboats.com/gallery/data/500/C...
Chrysler's sonoramic manifolds of 50 years ago came in 2 versions.
http://www.forwardlook.net/forums/forums/get-attac...
Originally with the center divider all the way to the carb, about 30 inches long for lower rpm power.
http://img.photobucket.com/albums/v628/BigBlockMop...
Then they cut the divider back so the tuned length was only about 15 inches long.
http://www.allpar.com/mopar/images/sonoramic4.jpg
RE: What is the advantage of Ford's SHO Split-Port intake manifold?
This was the situation at least with the 1960 & 1961 Chrysler 300, the model in which this feature was first introduced by Chrysler, if I'm not mistaken.
The same concept was also applied to the Dodge Dart and Plymouth Valiant, with the Slant-Six "Hyperpack" option, which if I recall correctly, allowed Chrysler to more or less sweep the short-lived compact NASCAR series in the early sixties. Naturally, there was more to the Hyperpack option than simply ram-tuned intake manifolding.
"Schiefgehen will, was schiefgehen kann" - das Murphygesetz
RE: What is the advantage of Ford's SHO Split-Port intake manifold?
You absolutely can feel the difference when either of the solenoid valves stops working and you're running along one of the "wrong" torque curves.
And yes, this engine will safely rev to 7500.
Norm
RE: What is the advantage of Ford's SHO Split-Port intake manifold?
Norm
RE: What is the advantage of Ford's SHO Split-Port intake manifold?
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?