ptuomov

Nice model, Hans. I think it's quite similar to Porsche's "Group B" manifold for the S3 engine, based on that one photo we have. Plenum comes in a little deeper and the runners have longer radius turns. Hope you get this to metal soon, it'll be a very nice manifold for manual transmission cars.

One quick question. Does this design clear the MAF in the stock location? Eyeballing it, looks to me like it won't. This is of course irrelevant to those who would be running the alpha N. But if you plan to run a MAF (say because of boost), is it possible to fit the stock MAF housing into this system? Or will it be then a dual-MAF conversion a la Nissan 300ZX and MAFs on the inlet pipes on top of the valve covers?

hans14914

No, it's impossible by my limited skills to make an equal length intake manifold work with the stock MAF (unless you use really short runners)

You could run this design with my MAF adapter and run the Ford cartridge sensors.

This is designed to used Sharktuner-A via alpha-n.

To comment on previous posts - I insisted on the machined fuel rails. The tolerances on the factory fuel rails are too sloppy to correspond with a machined lower. I see it as a real risk for fuel fires with the standard dimension lower o-ring. As the most frugal designer in the world, I see the fabricated fuel rail as a *must* for any machined lower - I intend on insisting that Greg not sell a manifold without rails. It's not a margin thing, it's a fire thing. I also designed special clips to hold injectors.

Take a look, I am sure you will agree!

GregBBRD

You don't need to insist, that was a given.

mark kibort

if it must use your fuel rails, will there be an adaption for the stock connections so that the stock dampers and RRFR mounting with return lines can be used?

V2Rocket

to derail this thread further, and add more british engineering..
Mark, take a look at the Land Rover 3.9 V8 intake manifold...this one has a bolt-on top you could use
And as factory fitment, it has equal-length runners with bell-mouths in the plenum...



This one shows that the trumpets are different heights, but the "outer" runners have longer paths, so the runners are truly equal...

GregBBRD

For a naturally aspirated car, I'm sure I will run a "y" intake pipe...so if someone wants to run a MAF, they will need to run two.

For a car with intake manifold pressure, I'm guessing that a single 4" inlet pipe would be plenty, so one could put a single MAF into that pipe.

GregBBRD

We ran stock dampers and regulators on the prototype, so certainly this will be possible. These pieces will obviously need to be relocated, so the stock fuel lines will not work.

Is this going to be desirable for the majority? Probably not so much.

Designing anything around Bosch parts that have not been needed in production for 20 years isn't a very smart thing to do...when Bosch runs out of this stuff, I'm certain that these pieces will be "gone" forever. (Try getting new Bosch fuel injection parts for an early 928...or an early 911.)

Knowing this, we decided to use more modern pieces.

We've incorporated the dampers into the fuel rails....and made provisions for 2 dampers on each side, if needed to control the surge problem because of batch firing the injectors. (When making 500+ horsepower, the volume change when opening 4 injectors at the same time is pretty large.)

The stock fuel pressure regulator is overwhelmed by an 044 pump, when running at lower rpms, which adds heat to the fuel. (Heating the fuel is not a desirable thing.) Therefore, we are running a different regulator that is capable of returning the volume of unused fuel that the 044 pump puts out.

The good news is that the dampers and regulator (fully adjustable) are much cheaper than the stock Bosch pieces.

The plumbing is a "rounding error" in the overall picture of the manifold.

You will be able to run your own injectors, if you want.

ptuomov

I think that manifold will work extremely well in a manual transmission car. Hope you get it in metal soon!

I played with the lego blocks and your flanges. To get the stock MAF to fit in the stock location, basically every pipe needs to be different if they have a round cross-section. And the "plenum in the valley" design is close to impossible.

Even the stock air box comes surprisingly far towards the front, and it's difficult to get the runners to clear it in this kind of "plenum in the valley" design.

Dual "cartridge" MAFs may be in the cards for me on some future date anyway, if I want to draw thru the MAFs. We'll see if I have to go there.

If you have a strong opinion on the fuel rails, then I'll have to get two of your sets.

Single 3" pipe would be plenty for feeding a 5.0L engine pressurized air, as long as it doesn't have small-radius turns. It's those kinds bends that kill you.

We've come to the conclusion that this sort of plenum box works better than a Y-pipe if the space is extremely constrained. With a lot of space, Y-pipe is better and more efficient, because the turn radii can be kept long enough. In a very space constrained setting, the plenum box can be made lower profile because the single outlet from the box can be made to draw air from the entire 360-degree circumference of the outlet pipe entry. For this reason, it will beat a Y-pipe that has a too tight turn radius. It will however lose to a long turn radius y-pipe because the box requires one to decelerate the air into the box with only limited pressure recovery. If the box inlet pipes can be made large, this inefficiency of the plenum box is reduced.





I think those conclusions apply both the normally aspirated and boosted air.

V2Rocket

You probably know this already, but if you mean the Ford/Hitachi type "slot MAF" since about 2005, they still seem to be pretty sensitive to pipe shape before the sensor (as with older MAF types).

When I had a MAF conversion on my 944, I had the MAF housing in place of the original AFM, with a cone filter clamped on the end, with the cone mounted inside a modified factory airbox. Basically there was ~3" of straight pipe between the sensor, and the filter element.

By adding a longer leg (12" long, 3" diameter 45* bend) between the sensor and the filter, the car started, cruised and WOT'd noticeably better.

Smooth, uniform airflow is critical for the MAF...

Dave928S

Brilliant .... I was going to ask you what you had planned for that extra point on each side. Equal placement of the dampers, and the option of an extra in each rail to further split injectors to pairs, should nip pressure waves in the bud close to the source, and minimise wave interference/mutiplication. Dampers in the rails also makes so much sense in minimising connections, and therefore leak points and hoses, and space saving. I've always thought that the factory layout is a bit of a overly complicated plumbing 'spaghetti factory' ... as is some of the wiring.

ptuomov

Thanks for the info. I can't say that I know much anything at all about what kinds of housing those slot MAF's need, and how important it is to have straight pipe before and after the slot MAF.

DKWalser

Hans, Greg, et al -- Wow! I'd almost given up on this thread, then you guys drop da bomb! Very cool.

V2Rocket

Luckily, there are lots of pretty options for housings in various lengths, diameters, and with/without a "flow straightener"...

http://www.ebay.com/itm/3-0-OD-76mm-...ZSzXJK&vxp=mtr

mark kibort

im still having a hard time understanding the theory that the stock regulator has a hard time returning the fuel to the tank... i mean, the pump doesnt know the fuel demands of the engine.. it just keeps on pumping the flow. some goees tothe engien and some goes back to the tank. at idle, much of the fuel is returned. in my car i had near 95% injector duration and 75lbs of pressure which meant, very little was going back to the tank i imagine.now with 30lb injectors and 40psi, there is still the same volume going back to the tank, but when the engine requires the additional fluel, its there in the form of larger flow capabilities of the injector. am i understanding this correctly. point is, i just dont understand how the RRFR wouldn't be ideally suited for a little extra HP than i have today. is the fuel heating a problem for all? just something you are addressing? i havent noticed any issues with idling performance or hot weather running WOT or idle with the stock stuff, augmented by the RRFR ive been using for many years now.

the next question i have is the plumbing.. sure, i have a resistance to change, but if its a rounding error to the system costs, sure, im game if it has no downsides to the stock stuff.

i would however, just want to plumb the air flow through the stock MAF, as joe and Mark did and use the stock ECU . i would be willing to cut out the MAF hot wire and mount it to a 4" pipe and then to a large cone filter in the a/C area under the windshield.

the intake looks amazing! at that price point. it makes no sense to hodge podge something together, unless i had a spare engine top block, a couple of dummy heads , was a great aluminum tig welder and had a ton of extra time on my hands!

ptuomov

Fuel heating is not a problem in a race car. It's a problem in a street car.

Suppose that you've sized the pump 25% over the peak fuel demand. If you are always using the peak fuel demand, then you're returning that 20% of the fuel pumped. No problem.

However, if you let the engine idle, then you're returning about >95% (or so) of the fuel. Now, the flow rate thru the regulator is about 5x what it's at peak power rpm WOT.

For a street car, the regulator and the pump either need a control logic or the regulator needs to be sized to return 100% of the fuel pumped by the pump without causing fuel heating beyond your tolerance.

The simplest way to understand how much the regulator heats up the fuel is to look at the flow rate thru the regulator and the pressure loss that the regulator causes. The pressure loss and flow rate determine the energy loss that will show up as heat, most of which will end up heating the fuel.

Fuel cooler helps somewhat, but if the problem is caused by something as simple to chance as the regulator, one should replace the regulator. If one would have to change the return lines to larger ones, that's a real bear of a job and at that point I'd consider all the alternatives before doing that.

The two risks are boiling the fuel and the pump cavitating or, a lesser issue, the engine running somewhat lean because of the thermal expansion of the fuel. The latter effect is large enough that I've been able to measure it.

I've boiled a lot of fuel. Before we got the 1k rwhp capable fuel system sorted out, you didn't want to cruise around the town with less than 1/4 tank full. We now have big lines going in, big capacity pressure regulators, and most importantly two pumps that get turned on based on fuel demand.