New Product: High-Performance Intake Runners for the 32v 928
07-09-2010, 10:20 PM
#46
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Carl...."Owing to the unique firing order of the 928, this balance tube will actually feed and equilibrate the forward-most cylinders (cyls 1 and 5) with air from the opposite plenum on every cycle. ...." Nothing unique about the firing order....all 302 / 5 liter HO fords, 351, and 4.6 as well as all newer Chev Gen III > Cadillacs 429-500 cubes from the 1960s. They all fire the same order (note GM numbers the cylinders differently but same order). Any 90 degree V-8 you have the piston at TDC twice during the 4 cycle, change the cams and you can fire it at either of the TDCs. Many aftermarket cams do switch. Also SBC sprint car engines are two valve motors as is NASCAR . The manifolds look great !
07-10-2010, 02:26 AM
#48
Drifting
Carl,
YOu have been busy and quiet on rennlist for some time and now all I hear is the THUNDER from your excellent work.
Now hurry up and let us know when the land speed record shot will occur and we will be there to cheer you on.!!!!!
andy
YOu have been busy and quiet on rennlist for some time and now all I hear is the THUNDER from your excellent work.
Now hurry up and let us know when the land speed record shot will occur and we will be there to cheer you on.!!!!!
andy
07-10-2010, 02:49 AM
#49
By James Bailey
I am making some enquires right now as to the cam swap. That is change the firing order. Given my cams have to be custom made what difference does it make putting different phased lobes on. I would like to know how much the change in firing order is worth? Ford recently did a study and changed to the more modern order. Obviously and the they did state that is was worth power and made the change.All Nascar engines now have the same firing order. What is it worth?
Greg
Carl...."Owing to the unique firing order of the 928, this balance tube will actually feed and equilibrate the forward-most cylinders (cyls 1 and 5) with air from the opposite plenum on every cycle. ...." Nothing unique about the firing order....all 302 / 5 liter HO fords, 351, and 4.6 as well as all newer Chev Gen III > Cadillacs 429-500 cubes from the 1960s. They all fire the same order (note GM numbers the cylinders differently but same order). Any 90 degree V-8 you have the piston at TDC twice during the 4 cycle, change the cams and you can fire it at either of the TDCs. Many aftermarket cams do switch. Also SBC sprint car engines are two valve motors as is NASCAR . The manifolds look great !
Greg
07-10-2010, 02:57 AM
#50
Nordschleife Master
Carl,
Havent gotten through the entire thread yet, but those look GREAT!
I could even make my own airbox to put on top, but i dont have to deal with the making up the runners, youve done it for me.
Now i need to find out what they cost.
EDIT: EHHH 2G or 4G, I dont think I will be buying a set
Still nice work
Havent gotten through the entire thread yet, but those look GREAT!
I could even make my own airbox to put on top, but i dont have to deal with the making up the runners, youve done it for me.
Now i need to find out what they cost.
EDIT: EHHH 2G or 4G, I dont think I will be buying a set
Still nice work
07-10-2010, 08:56 AM
#51
Craic Head
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Carl,
I see that you pegged all of the pressure tests at 200 deg. F. Then it handled the excessive pressures just fine. Have you tried any tests at higher temps? I don't know if this makes sense, but in order to find the limits, don't you have to exceed them a few times?
An amazing setup, and great progress toward having an 'off the shelf' alternative from intake all the way through to exhaust, body kits (plus some suspension and other performance goodies we're all aware of).
Keep up the great development and we're all rooting for you to take that record!
I see that you pegged all of the pressure tests at 200 deg. F. Then it handled the excessive pressures just fine. Have you tried any tests at higher temps? I don't know if this makes sense, but in order to find the limits, don't you have to exceed them a few times?
An amazing setup, and great progress toward having an 'off the shelf' alternative from intake all the way through to exhaust, body kits (plus some suspension and other performance goodies we're all aware of).
Keep up the great development and we're all rooting for you to take that record!
07-10-2010, 09:13 AM
#52
Three Wheelin'
Carl I have quite a few of your unique parts on my car and only recently I convinced my wife that I needed the alum TT. So this puts me in a quandry because I'm not sure how to break this news to her "honey the intake manifold broke again, I need a new one, and the old one in n/a". Damn you guys!
Great work again!
So there was no way to get the MAF to be in front and not at the back (like the vettes)?
Great work again!
So there was no way to get the MAF to be in front and not at the back (like the vettes)?
07-11-2010, 08:27 AM
#53
By Carl Fausett
Carl, looking at your plenum, it appears a bit small unless it is boosted, Prof. G.P. Blair states 10 litres for each litre of engine capacity and he found more power even around 16 litres of plenum volume, I would have thought you would have made it larger given your excellent work in relation to the 2 V custom plenum your made. Ignore the comment if the engine is forced. If it is forced my god it is big at around 400 CI and forced to 30 psi? Anyway it may help others designing plenums.
By Carl Fausett
For your application the short runners may be fine but normally for 7,000 rpm you would be around 14" at 11" or so you are at around 10,000 rpm. Anyway I would be interested in what you have to say on this.
You can see how they angle the runners inward to gain the extra length. Those runners are tuned for 8,400 rpm. I am not saying it wont work but you will lose the some of the benefits of the helmholz effect, you will probably end up with the weaker pulses, not that it will too noticeable for you with a 400 cube 30 psi monster but other engines may be adversely effected.
By Carl Fausett
You linked your heads on page one and they don't line up with the above statement, maybe your website needs updating? At what lift did you achieve 360 cfm? What size were the valves?
Cheers
Greg
We experimented with mock-ups of both round-roof plenums and flat-roof plenums.
For this application, the flat-roof was preferred as it placed our plenum volume closest to the ideal size we had calculated.
The sides, floor and roof of our plenum is made from 0.25” 6061 aluminum. That’s thicker than most would use, but we are designing for up to 30 psi of
boost, and that’s the reason for the wall thickness.
Now the plenum sides are added, as well as the inlet tubes at the rear of each plenum.
A “balance tube” is often only 3/4” in diameter, just enough to balance out plenum pressures. This one is a full 3.0” in diameter, and does more than that...
Owing to the unique firing order of the 928, this balance tube will actually feed and equilibrate the forward-most cylinders (cyls 1 and 5) with air from the opposite plenum on every cycle.
The finished plenums are placed atop the intake runners, and are waiting for
the intake tubing and throttle body to be attached.
They will handle 30 psi of boost, move enough air to support 800+ HP, and still fit under the hood of the 928!
For this application, the flat-roof was preferred as it placed our plenum volume closest to the ideal size we had calculated.
The sides, floor and roof of our plenum is made from 0.25” 6061 aluminum. That’s thicker than most would use, but we are designing for up to 30 psi of
boost, and that’s the reason for the wall thickness.
Now the plenum sides are added, as well as the inlet tubes at the rear of each plenum.
A “balance tube” is often only 3/4” in diameter, just enough to balance out plenum pressures. This one is a full 3.0” in diameter, and does more than that...
Owing to the unique firing order of the 928, this balance tube will actually feed and equilibrate the forward-most cylinders (cyls 1 and 5) with air from the opposite plenum on every cycle.
The finished plenums are placed atop the intake runners, and are waiting for
the intake tubing and throttle body to be attached.
They will handle 30 psi of boost, move enough air to support 800+ HP, and still fit under the hood of the 928!
By Carl Fausett
The Helmholtz Effect does not require a closed plenum to exist.
It does require a proper bell-mouth on the inlet end for the pressure wave to reverse and go back down the runner, and very smooth transitions (at the transition from intake runner to head, for example).
A lengthy bar stool conversation can be had about whether boosted engines benefit from the Helmholtz effect, or only naturally aspirated ones. My own opinion is that the physics are unchanged on a boosted engine, the valve still slaps shut into a rushing stream of air, the pressure wave is still created, and the Helmholtz effect is still real.
It does require a proper bell-mouth on the inlet end for the pressure wave to reverse and go back down the runner, and very smooth transitions (at the transition from intake runner to head, for example).
A lengthy bar stool conversation can be had about whether boosted engines benefit from the Helmholtz effect, or only naturally aspirated ones. My own opinion is that the physics are unchanged on a boosted engine, the valve still slaps shut into a rushing stream of air, the pressure wave is still created, and the Helmholtz effect is still real.
You can see how they angle the runners inward to gain the extra length. Those runners are tuned for 8,400 rpm. I am not saying it wont work but you will lose the some of the benefits of the helmholz effect, you will probably end up with the weaker pulses, not that it will too noticeable for you with a 400 cube 30 psi monster but other engines may be adversely effected.
By Carl Fausett
The formula for a Sprint Car engine is fairly well defined, and we know that in order to make 800 HP from a SBC engine with 4-valve heads we have to move 360 CFM through the heads of the 400 cubic inch V8. I wouldn't say its cook-book engineering, but it is a pretty good yardstick, and it tells me that I need to flow 360 CFM through the heads if I want to produce 800 HP as well with my 6.57L 928 motor (also 401ci)
So we flow-benched our heads, cams, and big valve package to make sure they would flow at least 360 CFM, and we got it.
And we tested our intake runners to make sure they would not be a restiction.... they have to flow 360 CFM also to support those heads. We worked them until they DID flow our numbers, and then we stopped.
So we flow-benched our heads, cams, and big valve package to make sure they would flow at least 360 CFM, and we got it.
And we tested our intake runners to make sure they would not be a restiction.... they have to flow 360 CFM also to support those heads. We worked them until they DID flow our numbers, and then we stopped.
Cheers
Greg
07-11-2010, 07:49 PM
#55
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Thread Starter
Jim Bailey: thanks for the kind words. You and I have already bar-stooled the "unique firing order" of the 928 a couple times.... I think its uncommon that we fire the same bank in succession 3 times per revolution. I also think thats where we get the great (and unique) 928 "sound" at the tailpipe. But I yield to your research and cetrainly agree other V8's in the history off the Ott-cycle engine have done it before as well. I didnt know the 301 and 351 Fords did.
Greg Gray: your exactly right, this setup is tuned for my intended application. If a tuner wanted more bottom end and mid-range, he'd want longer runner lengths. As to plenum volume, the engineers are all over the map on that, I have read from .8 to 4 times the cid. Remember to compute ram tube area as part of the plenum (the area from the throttle body into the plenum chamber is referred to as the ram tube, and part of the available reserve or plenum).
This too, gets tweaked based on the application. Larger plenums for NA applications, smaller for boosted. Too big and the engine will not decelerate immediatly upon throttle-off (so-called "plenum push") and you loose throttle response. Too small and you loose ultimate HP.
Thankfully, there is quite a range that plenum size can take with little effect one way or another, not unlike throttle body diameter. These two items
(plenum size and throttle body diameter) wont vary the performance as much as you might think (except at the extremes), so although they matter enough to do some math and calculations on, they are not as sensitive to size as intake runner diameter, taper, and length.
I am using a 105mm throttle body on this build (about 4.25" dia) and running two 3.0" tubes from it into each plenum.
As always, the space envelope on the 928 is one of the biggest challenges. The hood is LOW. The injectors are a fixed height, so that pretty much established the height of the plenum floor... just higher than the top of the injectors. The hood set the max plenum height. Your only other option is running the plenum wider and over the cam covers... like a 85-86 32v model.
Being boosted, I dont need as big of a plenum as a NA motor, and I do value throttle response in road racing... so I kept the plenum on the smaller side of the equations, but it is still plenty big enough.
These two plenums, although they appear small, already have 770 cubic inches or 12.6L of volume between them, not including the ram tube area.
I have a long ways to go before Bonneville for this year, and worried about whether we will make it. But if we dont, I can tell you it isnt for lack of effort!
Greg Gray: your exactly right, this setup is tuned for my intended application. If a tuner wanted more bottom end and mid-range, he'd want longer runner lengths. As to plenum volume, the engineers are all over the map on that, I have read from .8 to 4 times the cid. Remember to compute ram tube area as part of the plenum (the area from the throttle body into the plenum chamber is referred to as the ram tube, and part of the available reserve or plenum).
This too, gets tweaked based on the application. Larger plenums for NA applications, smaller for boosted. Too big and the engine will not decelerate immediatly upon throttle-off (so-called "plenum push") and you loose throttle response. Too small and you loose ultimate HP.
Thankfully, there is quite a range that plenum size can take with little effect one way or another, not unlike throttle body diameter. These two items
(plenum size and throttle body diameter) wont vary the performance as much as you might think (except at the extremes), so although they matter enough to do some math and calculations on, they are not as sensitive to size as intake runner diameter, taper, and length.
I am using a 105mm throttle body on this build (about 4.25" dia) and running two 3.0" tubes from it into each plenum.
As always, the space envelope on the 928 is one of the biggest challenges. The hood is LOW. The injectors are a fixed height, so that pretty much established the height of the plenum floor... just higher than the top of the injectors. The hood set the max plenum height. Your only other option is running the plenum wider and over the cam covers... like a 85-86 32v model.
Being boosted, I dont need as big of a plenum as a NA motor, and I do value throttle response in road racing... so I kept the plenum on the smaller side of the equations, but it is still plenty big enough.
These two plenums, although they appear small, already have 770 cubic inches or 12.6L of volume between them, not including the ram tube area.
I have a long ways to go before Bonneville for this year, and worried about whether we will make it. But if we dont, I can tell you it isnt for lack of effort!
07-11-2010, 08:39 PM
#56
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Actually 928 fires R,R,L,R,L,L,R,L never three in a row. Just like all the 5 liter H O Fords, New chevy, cadillac etc. The V-8 "Burble" most gearheads love is the sound of that irregular beat coming out of seperate dual exhaust tailpipes. Plumb a Mustang into a single exhaust and it will sound much like a 928. Put split exhaust manifolds on a straight 6 Chevy into dual pipes and suddenly it sounds like an old Jaguar, huge change in the sound.
07-11-2010, 08:48 PM
#57
Former Sponsor
07-11-2010, 08:59 PM
#58
Developer
Thread Starter
I concede the point. R,R,L,R,L,L,R,L Jim is right. I knew if I kept talking long enough I'd put my foot in it.
The SBC does it L,R,R,L,R,L,L,R - also same bank in succession 2 times per cycle.
The SBC does it L,R,R,L,R,L,L,R - also same bank in succession 2 times per cycle.
Last edited by Carl Fausett; 07-11-2010 at 09:31 PM.
07-11-2010, 09:12 PM
#59
Developer
Thread Starter
Greg Gray:
You might enjoy the article about the 16v intake manifold I designed/built last year.
It is here: ftp://12.234.229.133/installpdf/inta...folddesign.pdf
It enabled us to get 460 RWHP (540 crank) from a 5.1L 16v 928 engine.
You might enjoy the article about the 16v intake manifold I designed/built last year.
It is here: ftp://12.234.229.133/installpdf/inta...folddesign.pdf
It enabled us to get 460 RWHP (540 crank) from a 5.1L 16v 928 engine.
07-11-2010, 09:34 PM
#60
Agree Carl with your points about the plenum for the 32 V engine, if I was building one I would have them very similar to the early 32 V design with key improvements in runner design etc. Also the point you make is a good one regarding plenum size for a single throttle body car not so with a N/A ITB engine though, horses for course so to speak.
I have checked out you new design plenum for the 16 V and all due kudos to you in that design and research work. When I was proposing a larger plenum it was for ITB N/A engines. Air restricted engines want as large an plenum as possible.
I can also update the board regarding the firing order and advantages and disadvantages of our firing order. From what I heard it is of no consequence to power if you have an ITB setup. Some power will be lost with common plenum, around 10 hp on a 800 hp engine. Also most agree that main bearing life is better with the different firing order due to load spread. I suppose this is another reason to use a 8CW crank with lighter rotating assembly. We due have an advantage with a centre main bearing as previously discussed in a thread I started a while back. So I wont be changing the firing order.
Greg
I have checked out you new design plenum for the 16 V and all due kudos to you in that design and research work. When I was proposing a larger plenum it was for ITB N/A engines. Air restricted engines want as large an plenum as possible.
I can also update the board regarding the firing order and advantages and disadvantages of our firing order. From what I heard it is of no consequence to power if you have an ITB setup. Some power will be lost with common plenum, around 10 hp on a 800 hp engine. Also most agree that main bearing life is better with the different firing order due to load spread. I suppose this is another reason to use a 8CW crank with lighter rotating assembly. We due have an advantage with a centre main bearing as previously discussed in a thread I started a while back. So I wont be changing the firing order.
Greg