928mac

There are some questions I have.
Is not an ITB its own intake?
Wont each work more efficiently on its own, isn't that the idea

I would not close it all in and trap all that heat.
I just dont understand as each ITB only needs a filter on top.




If you want to mount a tube to the cool air intakes then I would modify one of the filter tubes like the ones Roger sells,(E something) so that it bolts right onto the ITB and then a flex tube to the front.
I have seen the cold air modified filter inlets at the rad housings, some of you have made. Imagine those chrome tubes sitting on top of the ITB (2 chrome tubes) and you should be able to unbolt them as easy as an air cleaner. I hope this helps stir some images

Here is Stirlings engine that I tried to draw it on but I do not have a good photo editor.
In this picture it shows the tube bolted to each ITB on the one side.
But the housing could be grooved to slide over the lip of the ITB and therefor there would be no holes in the tube and no mod to the ITB.
Its up to the builder.



This post is a copyright date and anyone selling this idea for personal gain sucks

SeanR

You will get a more even flow of air with an air box on top of them. Not to mention it will be cooler air.

mark kibort

lots of other factors. in the end, you want the least amount of pressure drop across the inlet. howeer, there are trade offs. cooler air being one of them. inlets contained in an air box that can support even flow its probably going to be best due to the cooler and higher air pressure found at the inlet of the system. (e.g. anderson , fan CF inlet and manifold system)

dr bob

With a feed log running across the tops of the intake bells, there will be significant "crosstalk" among the intakes due to uneven pulsing. You don't want the intake above the bell to be part of the resonance scheme. The box offers an easy way to even those out, plus it offeres air the path straight in, so the bells can perform correctly.

928mac

Yes I have thought of this Bob, but the log with 4 or the box with 8, would the difference be that much, even though the volume is greater with the box.
Each ITB on its own would be preferred.

Also the larger box will collect more heat.

The main reason for the ITB installation, if performance, will be the user/builders personal touch.
If it is also for the cool factor then you dont need to worry about squeezing every megajoule from the flux reactor.

The really hard part is will the log fit,???
and to pipe it from the rear would defeat the purpose because the extra pipe would add more heat.

mark kibort

just pipe it to the base of the windshield to solve the heat problem and i dont the intake can transfer much heat during WOT as the air flow is so fast. many of the non track guys havent done this, but at the track, a pitstop will show that the intake is very cool to the touch right after many hot laps, but warms up quicly in the paddock or idling around.

slate blue

For maximum power you need a large unrestricted air box or more correctly termed plenum. Studies have shown power gains are made in high power race engines when the size of the plenum is up to 16 liters per liter of engine capacity. So roughly a 100 liter plenum for the 928 stroker engine.

jcorenman

Brad, the problem with the two "logs", or split-plenum's with four cyl's each, is the firing order-- 1-3-7-2-6-5-4-8 in terms of left and right banks goes "right-right-left-right-left-left-right-left". If it were left-right-left-etc then the flow, and pulses, through the left and right plenum's would be uniform-- but it isn't, which causes uneven flow and lower plenum pressure for some cyl's. If you look at the S3 and S4 intake (both with variations of a split plenum), some cyl's are connected to the other side for that reason.

The ideal ITB intake would be as you described-- individual intake horns sticking up through the hood into cool, fresh air. Each intake would be drawing air directly from a huge plenum (planet earth) with no interaction.

You can't do that under the stock hood because the air behind the radiator is hot. The horns also need to fit under the hood somehow (either shorter or curved), and you need a filter, somewhere. The best approximation that I've seen is a large-as-possible airbox which is fed with cool, filtered air. I am sure there is a rule-of-thumb between airbox volume and stroke-volume to minimize interaction, but I don't know what it is-- I suspect the practical limit is what rules.

Cheers, Jim

blown 87

All in the name of VE, and little boost will do wonders for VE.

Mike Simard

A single filter on each throttle is an awful, unnecessary inefficiency.
Since it's a 4 stroke, each cylinder is drawing it's full air about 1/4 of the time.
By sharing a large single filter, each cylinder is able to get full use of the filter as though it were just there for every individual cylinder.
A shared filter(s) is a huge advantage but single filters are easy. Among the Cobra crowd there are those who care about looks and will actually choose single filters knowing that they are instantly giving up 50hp by doing so.

If you are thinking of a log filter for each bank, it's not as bad as individual filters but it's still a performance hit because of of the firing order not being even per bank.

928mac

The log could also be U shaped so that both are connected at the rear.
still having the duel intake on the front.

I dont want to beat this topic up.
It was a thought that I had that I wanted to share with everyone and get some feed back at the same time.

James Bailey

One big question for EFI is how are you going to measure airflow ?? If you plumb the intakes into a single box then you can measure how much air enters the box with a single mass airflow sensor.

jcorenman

We don't need to measure no stinkin' airflow.

If we know the throttle position (precisely), and the air pressure and temperature, then that's enough for the EFI. Which is precisely what John Speake's Alpha system does.

We've been running a ST-Alpha on our GT since April, stock intake with a piece of pipe (actually a gutted MAF) where the MAF is supposed to go. It's been running great, tuning has been absolutely stable, and throttle response seems better according to the buttometer (no MAF lag when opening the throttle to pass).

It's been to NC and back in June for SITM including a trip over Teton pass at 9500', and just got back from Anaheim and San Diego where it was 100F in the morning and 46F by the time we stopped in Yreka. (Silly fools, why were we heading north??). And around 20mpg on the highway at 75-80, where legal of course.

Cheers, Jim

928mac

You are right James.
A MAP or MAF sensor would be required.
If the U or H pattern is used a Map and air/temp sensor would work.
Two MAF sensors would be a bit much but if you were able to Y the two pipes to 1, then that issue would be solved.

These kind of things are never easy, thats why I through it out there.

How much room is above the cross brace when the hood is closed

the flyin' scotsman

the rise and fall of the pistons get you every time Brad.

Many manufacturers have played with crank config to phase out the pulses: the Honda 1234 is real good but the 6 is better. The 8 in the 928 design is not so good and you run into the issues noted above.

Now messing w/the fuel maps and tuning w/STII may get the gains your looking for or bolt on a blower, bore out the block then turbo.

A thought though.....you can hardly keep rubber on the car as is

"Me? Im just a lawnmower, you can tell me by the way I walk"