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Oil filler neck and water crossover mods are the least of your hurdles. Piece of cake! You're going to be using Alpha N with your new sharktuner, the lead to the MAF connection is 3 feet long. Order one now from John so you have it in hand while you're laying everything out.
Thanks for the pics. so, you move the one temp sensor to the side by drilling a hole and put a bolt in the other? so, you are thinking it should face forward too? i guess, i can just get the cabling and put the MAF infront of the radiator with the filter as anderson and fan did.
In terms of normally aspirated engine intake runner length, a car engine EFI system that has to fit under the hood should at minimum have the longest runners you can without making bends. Once you have to start making bends, then it becomes an interesting question whether straight and shorter is better and long and curvy.
I feel (but don't know) that you should keep the straight part of the runner small cross-section and then taper to wider diameter if you need to make bends. I think that if the runners are straight, then the stock S4 inside diameter intake runners can efficiently feed an engine almost double the stock power (with higher rpms and larger displacement, presumably).
Plenum volume is close to irrelevant in a single plane intake that feeds eight runners from the same plenum, as long as all runners are fed equally and without shrouding. The throttle body sizing can be done with a relatively simple formulas.
Air doesn't mind making bends as long as velocity is low. If you have bends in pipes feeding the plenum, as long as the cross-sectional areas of the feed tubes are large enough, they don't cause any appreciable power loss. Pipe flow equations and the same logic as the throttle body sizing equations use can be used to size the feed pipes, with bends or without bends, to produce an arbitrarily small power loss. In contrast, the intake runners feeding the individual cylinders *must* be small enough and the velocity in them high enough for good VE, so those can't simply be increased in size to eliminate losses. To summarize, if the runners are small diameter and straight and if the plenum feed tube is large diameter and curvy, it'll work out great.
There are so many assumptions here that it is hard to cut through the disinformation.
First of all my intake did 602 hp with the crappiest dyno headers known to mankind; it also maxed out at 6700rpm for safety reasons and because there was no point pushing it further on a chassis dyno. Once the motor is in the car with the real custom made MSDS headers that were specifically made for that application, and once we have the complete oiling system and vacuum system hooked up, we can really see what it will do on a chassis dyno.
I am not even sure how you can even make any kind of assumptions about torque with those headers.
The reason my manifold made more HP than the carbon one - 150hp over stock - is partly because the builder is one of the main suppliers of manifolds for NASCAR and while it was Carl's specs, it was the builder who extracted the kind of performance you are seeing out of this thing. It's pretty phenomenal.
My plan is to put the motor in the car, then cut the hood so you can all see how much it sticks up. From there, I will make a custom bulge to hide it all.
This is the design that aston martin came up with. its not too distant a relative to what the Boss 302 mustang uses, both with similar engine size and cam profiles (and compression ratios ) to what the 928S4 has today. yet, the 302 (5L) mustang produce 440rwhp with this type of manifold, and the aston martin, with its 4.3 or 4.7 Liter engien made near the same power. most of all the gains are in the intake, as we have seen with all the modified intakes so far on the 928 stroker motors. (anderson saw 100hp just bolting the CF intake on ), GB saw big gains with his, and Carl has shown 150hp with the nascar inspired intake.
the question is not whether it will work, the question is can we make it a bolt on affair. thats my goal.. not so much to maximize HP, but to gain hp but do it as easily as possible.
if i can weld this intake to a set of Hans' adapters and you can bolt this thing right on an S4, and get the gains with no fuss, no tuning, how great would that be. we already know this is possible with andersons intake. many of his tuned configurations were done with NO tuning, only fuel pressure sure, the stock config for tune was not optimal, but it was safe. (mixture and timing). this has been true with my engine. ive run safe for 8 years on the motor and over 100 hours, and even though its on the rich side, i dont know what the optimal gains would be, but i dont think it would be more than 10 -20hp more tops. (380ish as i run now vs the protected tuned value of near 400 with all stock S4 components and a 85 cam)
the challenge is making this fit. it looks like it can, especially since we are going to be lapping off the legs (runners) and re-directing them at the 1 and 4 cylinders, and the middle ones are not moved much. the question is rear facing TB or front facing TB and intake filter. both have their advantages, and neither will sacrifice HP based on intake ram pressure.(both have plenty of ambient , ram pressure air) the rear facing makes this more of a race car mod. (no ac can be present in the base of windshield area) but front facing means anyone can bolt this on with only the mods we all know we will need:
1. new throttle body and adaptation of existing throttle cables and pullleys
2. possible modification of temp sensors on water manifold
3. custom air flow tub to run over radiator , mounting MAF and Air filter pointing down in front of radiator (Ala Mark Anderson and Joe Fan style)
4 . minor modifications to intake to fit any breathers using existing ports or creating new ones.
5. cross bar modifications for chassis stiffness (ala anderson and fan)
So if I am reading that graph correctly, would the holy grail of intake runner design be one that would automatically vary its length with RPM? Hypothetically speaking of course.
Mark -- Having those runners 1, 4, 5, and 8 do an S curve is going to defeat the purpose to some extent.
I dont understand your observation. what do you mean, "s curve"? most of the gains are in the lack of pressure drop across the turns and bends and turbulence of the stock intake. the AM intake has bell mouthed inlets which are very important for flow efficiency, as well as the decreasing area as it mates the heads. they are optmal for flow.
what will be a problem is making the transition from the AM intake to the 928 head intake ports. but its a fraction of the problem that the stock intake had. i might even be able to use pliable joiners to attach the intake to the intake adapters , maybe at least initially to get the positioning correct.... then modify for a permanent design.
I dont understand your observation. what do you mean, "s curve"? most of the gains are in the lack of pressure drop across the turns and bends and turbulence of the stock intake. the AM intake has bell mouthed inlets which are very important for flow efficiency, as well as the decreasing area as it mates the heads. they are optmal for flow.
what will be a problem is making the transition from the AM intake to the 928 head intake ports. but its a fraction of the problem that the stock intake had. i might even be able to use pliable joiners to attach the intake to the intake adapters , maybe at least initially to get the positioning correct.... then modify for a permanent design.
The AM bore spacing is much narrower than that of the 928. That means you’ll have to make an S in the end runners, that is, two turns in opposite directions. It’s hard to get that S to flow well. It’s roughly analogous to running standard Webers on an old small block heads. Those don’t work well, unless you run the Webers far from the ports. To reduce the S angles, you could cut open and extend the plenum in the center but that would be a lot of work.
If you have a poorly flowing S curve in the runner, then you have no choice than to expand the runner cross sectional area to get the pressure drop down. That in turn reduces the velocity and kills the volumetric efficiency. Much like what happened with the stock S4 manifold and its curvy, oversized runners.
The AM bore spacing is much narrower than that of the 928. That means you’ll have to make an S in the end runners, that is, two turns in opposite directions. It’s hard to get that S to flow well. It’s roughly analogous to running standard Webers on an old small block heads. Those don’t work well, unless you run the Webers far from the ports. To reduce the S angles, you could cut open and extend the plenum in the center but that would be a lot of work.
If you have a poorly flowing S curve in the runner, then you have no choice than to expand the runner cross sectional area to get the pressure drop down. That in turn reduces the velocity and kills the volumetric efficiency. Much like what happened with the stock S4 manifold and its curvy, oversized runners.
That’s the big challenge here.
I see now what you are talking about. actually there is little change in direction, but does have an effect. orders of magnatude different than comparing the stock manifold where the air is forced to make an almost 180 degree change of direction. and all runners showing many different direction changes, unique to the runner #. as far as flow losses, i didn experiments many years ago and showing negligible losses if the changes in direction were subtle. im much more worried about the smoothness of the transition. that will be the challenge. but, as we have seen there are many square to round port adaptations, Carl's being one of them and he certainly had no issue with flow.
Ive got a 944S2 manifold and another on the way, that i will use for the adapter plates. i cant seem to find the Hans adapters. the last one was sold earlier this year.
any draw backs? seems like this would even be better due to more match tubing coming out of it, that i can blend higher up in the flow path to the AM runners.
thoughts? its aluminum so i suspect we can work with it.
It _was_ going to any number of beaten-to-death HP vs. torque discussion threads. But 33 posts on, it's _become_ a HP vs. torque discussion. So I guess it can stay right here.
This is Marks thread
We all know Mark wants HP above 4k RPM
Therefore, this is no debate in_this_thread.
On that note.
Yesterday in my automatic 87 I found myself behind a slow truck on an uphill cloverleaf leading to the highway (70mph speed limit). You can see oncoming traffic you'll be merging with long before you reach that point. Coast was clear, zero oncoming traffic. I manually dropped it into 2nd, RPM's settled at 3,800rpm.
At the top of the hill I merged to the far left lane, ran it to 6,000rpm, popped it into drive and away I went.
Guess I'm one of those rare fellows that runs my engines past 4k RPM
IMO, you'll be further ahead cutting the plenums off of each 944S2 intake and bolting the "runner stubs" to your 928 heads (flip the driver side one end for end), and then make a common plenum/tank to connect the runners kept as long as you can fit.
forget the AM intake project entirely, just use it as an "interesting benchmark" but put the saw down.
if you need another 944S2 intake(s) for experimenting, I have a spare one for $150 shipped,. or ill send you two of them for $300 shipped.
also, bear in mind the 944S2 intake ports are a little larger than 928S4. so either you'll want to blend the S4 intake ports, or fill in the runners a little.
Originally Posted by mark kibort
Ive got a 944S2 manifold and another on the way, that i will use for the adapter plates. i cant seem to find the Hans adapters. the last one was sold earlier this year.
any draw backs? seems like this would even be better due to more match tubing coming out of it, that i can blend higher up in the flow path to the AM runners.
thoughts? its aluminum so i suspect we can work with it.
Mark, take a picture with both the 944 and Aston intakes upside down, side-by-side, with runners matched as best you can so we can have an idea of the difference in runner spacing between the two.
How tall is the AM at the top-front and top-back of the plenum?
11-30-2017, 02:35 AM
