Duke

+1 for 2 injectors per cylinder on a high HP E85 4 cyl engine.

944obscene

The torque curve, peak power and overall driveability of the car are all determined by how it breathes. Just because you use an ITB design, doesn't mean you're sacrificing any of the above. In fact, you could tune for an improvement on at least TWO of the above without adversely effecting the third. With the right runner length and trumpet design, you can get a good jump in mid-range and top-end leaving you with a wide torque curve. And you will also get better throttle response, which we all know is a nice thing to have.

gt37vgt

the inprovement from ITB's on a turbo car are so marginal if at all .....no way they can justify there expense ....there are so many better ways to spend $2500

badcoupe

talk to kinsler about connecting the throttle shafts without binding etc. they have a slick setup, the older hillborn setups were prone to sticking. We use itb's and mech injection on our USAC motors. They built and adjustable spacing itb unit that I always thought would be sweet on street car with a speed density conversion.

Chris Prack

How many here have actually used a flow bench themselves? lol There is a bunch of half assed theory and speculation going on. The reality is, it all doesn't mean crap if you don't test it correctly. There are a lot of variables to consider and flow is just one and not the most important one.

944obscene

Why don't you shed some light then?

Chris Prack

What would you like to know? I am not an expert with a flowbench but I have been through the process with a guy that is. So I do have some real life experience.

Selecting valve size, port size and config, cam design, velocity stack, intake plenum etc.

944obscene

Not worried about parts IN the head. Just wondering what all, concenring the manifold designs themselves, we can interest ourselves with. Because as far as I know, and as far as I'm concerned, flow is all that matters at the end of the day with an intake manifold. That was the retort I was getting at.

From the diameter of the throttle plates (supposing were studying an ITB setup), to the length of the runners, trumpets and the taper therein, we change the dynamics of the airflow and where you'll see peak power, torque etc.

Shorter runners flow better up top, but destort VE and breathability down low. Longer runners and trumpets result in better low-end and mid-range. A good toss-up is to see what benefits your motor and setup the most and build accordingly. I'll leave it to Mike to say what they're targeting, but I'll be interested in a design for the right price. If not just to get rid of the stock little tb. I know it's a bad reason to want one. Don't care.

Chris Prack

Here lies the problem. Everything matters. You can't just leave one part out and assume it is going to be good. What good is flow if there is no velocity? You can have a ton of flow but poor velocity. You will end up with poor or uneven cylinder fill just to start. The intake is just the beginning. Cam lift, duration and overlap play a big role in what your ITB's (or any other manifold) will do in the real world. An engine is just an air pump and moving air efficiently is the key. Focusing on flow numbers alone is a waste of time. Let's say the ITB's can flow 300cfm but the intake port can only flow 240cfm with a stock cam. What happens to the air stream? What kind of velocity do you have? Adding an injector port above the throttle plate (or after) will affect the air stream. As will many other things.

The point I am making is you cannot discount any part of the engine. The whole idea is to fill the cylinder quickly and completely. Having more flow means nothing if it cannot get into the cylinder. This process is very involved and takes a lot of time. The best ITB manifold that could be brought to market would have interchangeable parts, runner diameters in various lengths, second injector options, throttle plate diameters etc. There is no free lunch and one manifold brought to market will only be done so to make money and sold to people that want it because it is shiny or looks cool. IMO this same company has done it once already. I have my own test results on the same engine back to back. But who knows? Maybe this new manifold will be enough of a compromise to actually benefit some people. I am not saying it can't be done but it will take due diligence to find a good average set up but I doubt that much effort will be put into it otherwise the cost of the product would go up dramatically to pay for testing time.

I am supposed to have an agenda because I say this but yet I don't sell anything to anyone. Hell, I don't even work in a retail environment of any kind. I do have 25+ years working on Porsche cars and I offer my experience and help to other people for free. I am not involved in any way other than to offer another point of view or opinion. People can chose to listen or not. In the end it does not affect me in any way.

Chris White

The flow bench I use sucks....

Chris Prack

What do you have?

seattle951

This is pretty much what the Mustang people were telling me when I was in the market for my GT supercharger upgrade. Coming up with the proper formula is expensive, and time consuming. Most them were running computer simulations and building products for optimized scenarios.

For what it is worth, I plan to install a JME camshaft, springs and retainers after my car passes emissions testing (last one). I discussed my current intake manifold with JME and they asked me to return to a stock manifold before impelmenting their product. They balanced and tested their product for the stock manifold. They were not confident of results if I retained the aftermarket manifold.

I sill like the idea of creating a 16v turbo motor with off the shelf parts if someone would build the right equipment. If this were done and tested, I would seriously consider buying the package.

944obscene

This sounds a lot like what I say. In the end, it's about increasing the efficiency of an air pump. An air pump that just so happens to light air and fuel on fire.

I, however, was concentrating on the intake manifold. Recognizing that all things make a difference, and that one thing can't be changed without exposing the weaknesses of something else, I still just want to concentrate on the issue at hand... A better flowing intake. With that said, I don't think you should just toss really big 90mm throttle bodies on and hope for the best, just because they can outflow the engine entirely. There is a lot of engineering behind the optimal setup. But you're being too anul and a bit pessimistic, I might add. I mean. We could be having the same discussion about turbochargers and you'd be preaching on size vs actual benefits etc. But that's not the point here. Supposing we could nail a target goal, on a specific displacment engine, with a specific design, then we could specify parameters with which to properly build and spec an intake system to comply.

So... Lets say that the target crowd of people using this manifold are going to be over 300hp, but probably less than 500. In general. Just a demographic of people that may or may not use this. So I'd fall in that category with the setup that I want to do next year. I'm thinking a 60-1, or GT30, with a cam, and some head work. But this will come one at a time, and I wouldn't be able to specify gains and weaknesses unless testing everything thoroughly. Which I probably won't. I'm hasty and I'm impatient. I just want to try to blueprint things to the best of my abilities, get parts and tune. Thus my thread earlier about turbo size, vs. air consumption at a certain power level.

So if I were targeting 350-400whp, with a 60-1, running a ported head, stock valves and a mild cam (for the sake of streetability), what could we assume the optimal design would be? I mean. It can't be too hard to find something that will work for a general power range. Hell, Look at Toyota.

The 4AGE which, I've studied, is a 1.6 liter motor that came with ITB's in Silvertop and Blacktop trim. The intake they used on those motors works great for stock and modded applications. It just does. Boosted, NA, you can really explore the power potential of that motor. So who's to say that you need to spec EVERYTHING to an exact measurement? That is what you basically stated. Can't have this without that. Can't do this without tweaking something else. In blueprinting a racecar this may hold true, but for most of us, we're really not going to see a differences in a couple millimeters of runner length, or injector placement. Nothing to really fret over anyway.

So I think that if you're going to design something like this, you can still find a tween where something works for multiple setups. Just thinking out loud. I agree with what you're saying, but only to a certain extent.

Chris Prack

I also said " I am not saying it can't be done but it will take due diligence to find a good average set up but I doubt that much effort will be put into it otherwise the cost of the product would go up dramatically to pay for testing time."

Their product may turn out to be great. It may work really well for the majority of those who buy it. I have my doubts but I won't be purchasing it so I have nothing to worry about. When the OP starts talking about flow numbers, some people who won't know any better, could assume that is enough to make it great. I am just pointing out that flow does not equal volume or power and drivability.

gt37vgt

on a turbo car everyones research has shown that the inlet manfold does have the profond tuning effect that cams valve size turbo size have .
it is basicly a restiction so short runners are helpful as they are les rescrictive .
and basicly the runners should simply be a little bigger then the port with a nice little taper .then all the velocity / flow tuning is still done in the port
take a look all the Jap things making big specific power with very crude $200 ebay inlets .