Unfortunately he was never able to really get anywhere with that setup. For one, none of the race organizations would let him run with it, so the only place he could run was the World Street Nationals IIRC. Then, on top of that, I remember reading that he had a really hard time getting the tune dialed in, so he ended up just junking the whole project.

 

Most of the Supercharged Mustangs/Lightning Trucks with either the Eaton or the Lysholm Supercharger had the Inter-cooler inside the Intake Manifold. It cooled the charge from the Supercharger and still allowed a inter-cooler after the boosting device and before the intake runners. Something that the older Roots
systems did not normally allow.

Here are a couple of photos of Lysholm S/C engines I have personally worked on:

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Show Bus Engine: Both engines were designed to run on 3 different fuels:
Gasoline, E-85, or Hydrogen.

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If you look close at Moran's engine you will see that it is a bunch of "Smoke and Mirrors" on the intake side.

He had all of that tubing going to the turbos and the engine would have been "bare" looking at the top. So he makes two header tube runner systems that pick up air from the intercooler and then runs down 4 tubes into a common TUNNEL RAM open plenum mounted on the engine.

He could have just as easily fed the plenum with two typical feed pipes and moved the throttle bodies closer to the plenum.

Tom Vaught

 

Very interesting. Something I wanted to point out with the plenum volume I've been thinking about is that a typical 20lb (gas grill) LP tank is approximately 5.9 gallons capacity or 1363 CI. A disposable freon tank is typically ~3 gallons, or 693 CI. Just some size references so that people can visualize a little easier what we're talking about. I've been contemplating doing a budget EFI intake with a freon tank, since I'm in the 300 CID range it should work fairly well. Probably one of those "when I get to it in 202X" projects however.

 

Moran's been known to hide things from his competition, so my first thought was perhaps the tunnel ram plenum was a fake, but from the layout and welding on the plenum (see otherpics on Google) I agree w/ Tom. There's also no plenum on the 'merge collector' side of the pipes which makes more sense if (since) there's a plenum after the tubes. Perhaps the exhaust-manifold-turned-intake is there to help diffuse the air more evenly into the plenum (instead of the traditional 90deg tapered plenum)?

Re: Intercooler in intake manifold
Using the intercooler in the intake manifold with a positive displacement blower seems relatively intuitive due to packaging constraints, but not so much with a turbocharger.

Don, the air filter is certainly feasible, that was just the first thing that came to mind as a concern.

Regards,
Kurt

 

Oem:

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Interesting, if you're looking to run that long of an intake runner.

 

All this talk/ thought about exhaust manifolds as intake manifolds got me thinking: Anybody ever experimented with unequal length intake runners?

Back in my drag racing days I heard that ProStock** builders had tried them in the past with the intent being to widen the powerband, but as technology facilitated higher rpms, and gears got (numerically) narrower, the need for the wide powerband diminished, so the unequal length runners fell by the wayside.

*** I'm not sure if this was NHRA ProStock, or mountain motor ProStock.

Any validity to the "wider powerband" claim? At first glance it kinda makes sense, on further inspection it's only *some* (~1/2) of the cylinders creating the "wider" torque, so it might all be moot.

Regards,
Kurt

 

I've read the same thing pertaining to the exhaust side. Running slightly unequal length primaries.

 

You pretty much answered your own question in a lot of ways. I'm going to do examples with a manual box, but the thing to remember is that an automatic with a converter would likely give you more "wiggle room" than this.

For a while there, I was infactuated with the idea of a variable runner length intake manifold. A lot of both high performance engines and high tech engines used them to help reduce compromise. That meant I ran a lot of intake runner length variations through Engine Analyzer, and would basically overlap the curve. For the complexity of it, I found out that the gains weren't worth it for a drag situation for the following reason:

With a few exceptions ("granny gear" transmissions come to mind) that anything with closish ratios wouldn't really be able to take advantage of the extra usable RPM in a drag setting. The easiest way to know how to shift is you use the following formula:

Gr1*TQRPM1<TQRPM2*Gr2

TQRPM2 is going to be peak torque, Gr1 is going to be the gear you're currently in and Gr2 is going to be the next gear.

As an example:

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This is the dyno chart for a 'busa. It's a bit out of the normal RPM range, but it doesn't really matter. You can apply this almost universally, I'm sure there is an exception or two to the rule but isn't there always? Jacked from another site, 99 gear ratios:

6th
24/ 23 (1.043:1)

5th
25/ 22 (1.136:1)

4th
27/ 21 (1.285:1)

3rd
29/ 19 (1.526:1)

2nd
31/ 16 (1.937:1)

1st
34/ 13 (2.615:1)

So, lets take the first set of ratios 1 to 2 shift. We know that peak torque for this engine is 98 ft-lbs*1.937=189.826 ft-lbs output in second gear if the trans drops down to where peak torque occurs. If we divide this number by the first gear ratio, we get 72.59 ft-lbs. So we go to the dyno chart and look to see where it drops off to that level. In this case, it's probably damn near 11K. He may be short shifting it just because he's near redline. Naturally, the flatter and broader the torque curve is, the higher up you can shift which is why this is considered a "valued metric" in evaluation of an engine's output. It also means it will have good average power which is also another metric involved, and an enabler of an intake making great power. The next question of course becomes how do we know how much RPM the engine has dropped? On a manual this is easy, as we are direct driven. It's simply a formulation of RPM*2nd gear/1st gear. In this case with an 11K shift point that would be ~8150 RPM. If you notice we're not 100% back to the peak torque level which means that the power band or the gearing could theoretically be tweaked some, but at the same time it's close enough it probably wouldn't leave altogether much on the table. Trying this again with the 2-3 shift:

98*1.526/1.937=77.2 ft-lbs which is ~10,600 in this chart
10,600*1.526/1.937=8350 RPM

Notice how the drop puts it into roughly the same region. It should every time unless it's a radically "granny geared" box. As an example, lets assume a 700R4 is a manual transmission. 1st is 3.06, second is 1.48. Assuming the same 10,600 RPM redline:

10,600*1.63/3.06=5,646.4 RPM

Note the huge drop? This is why "close ratio" boxes are considered valuable for road racers, and why the 700R4 is sneered at by some for performance applications. To rebuild almost 50% of your RPM is a huge loss of inertia, a huge shock to parts and you have to have a super wide power band that in general is nowhere near what most people would want to build an engine for.

Sort of an off topic rant, but I figured that some whys would be a vaulable contribution to the thread besides hows.

 

I'm assuming using a CFD program is great if the information entered is accurate. Could water be used to simulate flows and pressure in different designs?

 

I don't think so. Water doesn't compress like air, so the pulses would be completely different with water.

 

Talking about the intercooler in the intake i've been running this on my D/D 2V and with a ported case and coated M90 make 10psi and the runner length gives it a shit ton of low in torque.

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I wonder what size in-plenum intercooler would be required to support the cfm for 1,500+ bhp?

 

I don't think it would be possible to tell the truth. Hell it would have to be 6 times the size of this one to handle 1500hp. Like i said with a ported aftermarket case with coated rotors and case running a 2.250 pully it makes 386rwhp but puts out 448fpt on a stock 2V with rods & pistons. And with that small pully im over spinning the shit out of it and have to replace it about every 15,000 miles. I keep 2 spares so i can swap these out when the bearing go out. I have seen where someone took one of these and welded a floor it it where the blower blows through the bottom and welded a TB flange on the front and used it with an F2 cen and it worked very well but was running an A/W intercooler on it. Going to do away with this set up soon and plan on playing around with the intake and see what it will do, the runners have a stright shot to the head and has a lot of meat in it to play with.

 

Wow, that's hairy for an M90 to be cranking that kind of power out. Always heard low 300 at the wheels was about it for em.

Cool intake design, although I'd think the runner length is fairly moderate (~8 inches as a guess) on those. Can't exactly vouch for the runner in the head however, it could be significantly longer.

 

I've bolted a stock M90 on it one time when i was going to have to wait 30 days to get mine back and it would only make 7 psi , it's the $600 aftermarket ported and coated case and coated rotors plus the guy i send them to really knows his shit with blowers and have worked on the M90 for years. He can take one thats making 7psi and get 8 out of it just by timing the rotors.

 

Question I'll toss out about runner length. The runner length is based off the harmonics of the system and ideally the pulse hits the intake valve on opening to increase the pressure. That being said however, my question is when pulse tuning runner length does the harmonic being even or odd matter? I would think it would be similar to electrical where you can wind up with the harmonic being 180 degrees out of phase and therefore weakening the pulse.

 

I'll take a stab at answering your question. I believe the harmonic is the 'length' where the pulse is correctly timed. In other words, if 1st harm is 20" and 2nd harm is 15", a runner length of 17.5" would be the 'worst' possible length under the given criteria. Those numbers are fictitious and only used as an example.

I think about harmonics as a bouncing ball. Every time the ball hits the ground, it loses a little height (strength). A ball that has only bounced one time goes much higher than a ball that's already bounced three times.

Have a good day!
Michael