Chris Prack

What you are referring to is called the "choke point" and you are correct. Short runners with a nice transition with the choke point in the intake port. The biggest restriction in the intake tract is the intake valve itself. Now we get into cam profiles which is best suited for another thread.

JohnKoaWood

I thought the biggest restiction was the throttle body, but only at idle...

95ONE

No, the biggest restriction in any car is the joker behind the wheel.

gt37vgt

all discussions are at full throttle

Mike Lindsey

Tapered runners, 2nd row of injectors if you want (it's set up to accept them now, but you may need some hood clearance), 45 or 48mm throttle blades, various plenum sizes if your not happy with 1.5 times the engines CI, and velocity stack type inlets. Can add 25 or 50mm runner length. Connects to stock throttle cable. Doesn't require turbo modifications to fit. Uses existing fuel rail. Retains idle stabilizer. Uses stock TPS.

It does require a new charge pipe to the intake. This has a 3" pipe which we will be adding a 4 hot wire MAF in that pipe once it's working with pre-turbo MAF first.

Covered most of the bases on this project to make adjustable and minimize additional work or parts.

Flowing the intake will tell you if you have a decent design. It answers questions like will
it be a restriction for the head or not. Does it favor one of more cylinders. Sure, it will
flow less when you bolt it to a head. That's a given. But the only way you would know which
of the two is the problem is to flow them separately when designing them.

If it didn't flow what we needed it to, we would go back and figure out why, and re-design and
try again. It passed way beyond our goals with flying colors the first time.

Chris White

Hmmm...maybe here is another thing I won't have to finish. I have had some individual throttle bodies in my shop for the last 5-6 years...I love it when somebody else finishish my projects for me! Now I can worry about something else!

Mike Lindsey

Chris, just like our dry sump kit! LOL

We plan to post a picture today or tomorrow. At the moment it's apart finishing the throtle
cam positioning and clocking of the tps to shaft adapter. Once back together, and back on
the engine, well let you see what we got so far.

DanaT

OK. I think that this whole "flow" thing seems to be misunderstood even by the guys who claim to know flow benches. A flow bench has one very basic fundamental assumption. It assumes laminar flow in on direction.

If you have ever seen a motorcycle engine with four carbs and no air filters (in bikes such as the old GSXR where you can see the carbs) run on a dyno you notice something. Imagine just looking at the velocity stacks. You don't see air going in. You see a haze a around the carbs where air/fuel is pulsating back and forth. What is really happening is you are getting airflow going by creating a vacuum inside the cylinder and the atmospheric pressure (or even boosted pressure) forces air to fill the vacuum. Keep in mind that gasses flow in the positive direction. Once you get this air moving, you abruptly close the valve and the air column stops. Well, it doesnt really stop. You have a mass of material that is moving. It his a wall, compresses, then returns energy in the opposite direction.

What you have a is an air intake RESONANCE. This resonance is why tube diameter to length matters and manifolds are tuned for specific (or broad in the case of uneven length) frequencies.

Think of it this way (and I am no musician but understand resonance in mechanical systems). If you have a very slow 100% viscous flow of air through a clarinet, what sound will it make? When you vibrate the air inside of instruments, you are creating resonances that are amplified (think blowing in a beer bottle also) by the shape. You then change pitch (resonance) by altering the resonator. The experiment so people get a conceptual idea (and have some fun in the name of science).

Go buy some of the little 8oz coronas. Empty them (i would suggest by drinking them).
Next up. Get some nice 12oz bottles of you favorite beer. Again empty them (drinking).
Next go get s few bombers (22oz) beers. Empty them.
So that we have significant sample size, you need at least 6 of each (or at least tell you wife that).

Next go blow in them and listen to the pitch. An 8oz, 12oz, and 22 oz beer bottle are all tuned for a different frequency. Blowing in the beer bottle is the same think as the engine with the valve shut. You are setting up resonances. If you make peak power right at a resonance, you will gain power.

This is the whole idea of variable intake plenums. Factories can afford to do that. Most aftermarket suppliers can. They just go for a big number up top.

-Dana

Chris Prack

There is a lot left out that I didn't feel added to my point. We could post a ton of info but to what end? lol A flow bench is just a tool. My issue is too many people either use it incorrectly or throw around flow numbers as the be all end all to making power.

I do like the beer drinking part in your example.

Mike Lindsey

We "throw" around flow numbers to show percentage of gain or improvement or how our part or work may compare to someone else's. Or perhaps how a part may work in conjunction with ours or someone else's part. We don't quote flow numbers and make ANY claims as to how much power you may gain from that flow number. It's a reference, a comparison, a measurement and means of compare. Without it, how do you know what your paying for?

For example, we quote head flow numbers. If you don't have the same air, the same base plate size (bore), the same inlet plate or profile, your numbers will be different. That's why we post the original number, and final number, and most important, the percentage of gain. So anybody can take a stock head at their location, flow it, then flow ours, and with your air, see the same percentage of gain. Even if your set-up is different. There are those out there who think you just throw it in on a flow bench, and if it's not the same, someone is BS'ing. We guarantee our percentage of gain, and the reason we do, is because each and every head and intake is flowed on the bench to achieve them during the build process. Not just a, "we flowed our first one, and that's what it did" game. Those that don't quote flow numbers, are the ones you need to worry about what your getting. We feel if it was better then ours, they would certainly advertise that. They do on everything else that they feel is.

So lets say we have a head that flows 250 at 480" lift. Throw in a 550 lift cam, you might be in the 280-290 range, on a good 8v head with big valves like our Stage 4 or 5. That's why we need to know if our intake flows at least that. Otherwise it's the weak link, and the head work is not being fully utilized. As we keep building better and bigger heads, they
need support ahead of them.

We wouldn't want to sell a intake that didn't support our heads, and this is how we know. It's not just a guess. Once we know some HP numbers, from our or our customers work, we will advertise or make that claim. In the mean time, flow can be a helpful tool.

gt37vgt

every one knows I'm too cheap to buy one and i will just try make one from old beer bottle caps ...but how much mike ??

Chris White

I have seen the pictures of the prototype – its pretty nice. The most critical part of any multi throttle set up is the linkage – if there is any slop or misalignment the idle will truly suck. On carbs you can get away with it because each throttle is self metering – but with fuel injection the throttles have to be perfect or you will have a huge A/F variance at idle and small throttle openings.

It looks like the Lindsey set up has a very good linkage. It also fits with the stock brake booster heat shields and the runner length can be tuned to suit the engine.

I am tempted to run one on the 3.1 16v tack car engine….with two sets on injectors set up to run staged. The Tec system will allow you to run two sets on injectors- it runs the first set (mounted close to the head) up to 90% and then starts the second set. Much nicer than just firing two injectors!

BTW – intake tuning is similar to Theil / Small aligned vented speaker enclosures (and hemholtz resonators). I used to be a speaker geek…I still love the sound of a good transmission line enclosure!

alxdgr8

Mmmm....good ol' transmission lines! Interesting tidbit...I worked with Dr. Small last summer at my internship (i'm an acoustical engineer). Sadly he retired. One of the most intelligent people I've ever met.

67King

I used to work on that engine (hated it, too). Just wait until the 2011 GT comes out. That's the last one I worked on. Anyway, the tools that OEM's have are very, very impressive. Without getting into details, I used Excel to come up with a way to show data without the tools (only approved programs got time with them, and I liked to stir up trouble). I spent a couple of years writing an Excel model, it is about 9MB. That doesn't so much get into intake tuning as much as valve size, cam events, and flow coefficients.

For whatever it is worth, the "process" for all of this starts with RPM. Use that to determine what valve size you need, assuming it will fit. That will tell you the port size. Then you decide what peak RPM you want your torque peak at. That tells you your length. If you for whatever reason want bigger runners, your length will increase. That is oversimplifying it. You can gain a few horsepower by tapering the runner for the whole length, but that is very hard to package.

Where the complicated CFD comes into play is when you try to package this stuff. There are a lot of rules of thumb that come into play, one of the more important ones is that you want your radius of curvature on any bends to be twice the ID of the runner. You also want to make it oval around bends to try to keep the velocity uniform through the cross section. But, simple math is all that is needed to set targets. You then run a DOE around a few variables to see about tweaking it (this is a different model than the CFD ones).

Another big rule of thumb is that you need a straight length 4 times the ID before your bends change direction (aka "S bends"). So IMHO, the factory intake has a LOT of room for improvement. Especially in the rear cylinders.

It is almost unheard of to flow intake manifolds. The only time I ever saw it was when we were benchmarking (rather than scanning the intakes and reverse engineering them to do CFD). We flowed heads all of the time, but not intakes. You can make a bad design flow well by making it larger, but it won't tune for crap. That gets into the velocity that was mentioned earlier. You want the velocity to be as high as you can get it, so long as you don't get into being mach limited (average flow velocities through a port should be 100-110m/s at peak power). Any change in size from the intake to the hed will cause losses, I don't care how well what flows. In other words, teh size of the intake runners should be defined by the size of the port in the head, which should be defined by the valve size. If you hog the crap out of a port without changing the valve, you are making things worse. Porting is about shaping, not enlarging (unless you change the valve).

As far as ITB's go, that's really about allowing you to use a bigger cam. The biggest place you'll see it is at idle, part throttle, etc. There is no doubt that the intake will sell to people that don't need it, a fool and his money are soon parted. But, that doesn't mean the product isn't useful to the right people.

So yeah, anyway, intakes are complicated. There's a whole lot more to it than just flow numbers. Not many people have the right tools to properly develop an intake. That doesn't mean flow numbers can't be useful. if you know the bend radii, you can calculate your losses. Compare the intake with a straight pipe under the same conditions, and you'll have verification of your design. But, if you design your intake just to flow, you are probably going to be disappointed with the performance.

Having said all of that......I'm not making any comments on the intake one way or another. Lindsey has a good reputation, but I've never used them. I would have a hard time believing they'd be this well known and respected if they didn't do their homework. I would imagine the issues brought up by one poster are probably similar to what I said could happen above - ignorant customers buying the wrong parts (and I've been there and done that before, folks!). But, I'd caution people in looking at flow numbers alone as a useful metric.

seattle951

5.0L, 32 valves and 400HP/400TQ. Very similar HP/TQ figures to the car I sold, but without a whining supercharger. I might have to buy another one if the economy comes back.

Any thoughts on what Shelby or Roush invest on R&D on intake manifolds?

I would image in the case of Roush, the R&D cost is spread out over a large number of units keeping prices relatively low. Since Ford warranties the Roush upgrades for 3 years or 36,000 miles, I would also guess that Ford engineers were involved in the R&D process and probably made their engineering labs and computer systems available. Very interesting topic.