HP & Torque numbers for Cross Ram

[ERA 626]

I am getting mixed statement from different builders.
I am having Morrison make me a cross ram stack Fuel injection setup. I have a local builder friend (extremely old school) who has offered to build my motor. He has recommended using the megasquirt with a cam sync sensor (no distributor) he has done one of these on a SBF and runs great on the run stand. I am having a cam sync sensor custom made as well, nobody makes one for an FE.

I want to get 600hp/600 torque numbers from a 482 CI shelby Block/heads.
Soon after I jumped into this (ship my block & heads to new zealand) I met Joe. Joe is the engine builder for Shelby engine Co. Very humble nice guy. Joe has built hundreds of FE motors, he knows his motors.

My local guy (wont mention names) lets just say Dave. When I told Dave I wanted these numbers he called me stupid and ignorant. Yet Joe said no problem, but Joe is not a mega squirt guy. I am reading all over the internet these numbers are very doable and very common on a high end FE build. am I being un realistic to expect these numbers and still have an enjoyable fun to drive cobra? I do have extensive race history on a 110mph Shifter Kart, so performance/power is important to me. Advise?

[eschaider]

The numbers you are asking for are easily doable on an engine that big. You are only talking about 1.24 HP per cubic inch. That is a walk in the park with one arm tied behind your back. The MS3Pro Ultimate or MS3Pro systems are the poor man's Haltech / Motec equivalent. It is a great system easily tunable and comes with self learning capabilities to get you up and running quickly. The MS3Pro systems support Alpha-N, Speed density and MAF based fueling models. MAF based works always, everywhere all the time — use it, you'll love it!

You are likely experiencing some form of prejudicial behavior from the guy who poo-poos your power target. The lack of Megasquirt experience with Joe from Shelby is just that, a lack of familiarity and possibly some prejudice from the early days when they offered only Heathkit style systems. Very different today. Check them out here => MS3Pro Ultimate and they come with a lifetime warranty — only one in the industry.

All your requests and equipment choices are realistic and very solid products. Have your friend at Shelby do your engine and ask him to use the MS3Pro Ultimate system with a MAF from these guys => Pro-M Racing.

When you ask why use that MAF take a few minutes and look at this YouTube video => Pro-M Signal Quality

[olddog]

MAF is a challenge with the 8 stack. You either have to use 8 MAFs (one for each stack) or you could try one MAF on one stack. I think the Megasquirt will certainly let you do one MAF on each side of the engine (total of two). I doubt it will support 8 MAF, but maybe so.

Or you could build a removable plenum to seal up to the 8 stacks and have one opening to pull air through and put a single MAF there. If so might as well pipe it to a cool air source while your at it.

[eschaider]

Originally Posted by olddog

MAF is a challenge with the 8 stack. You either have to use 8 MAFs (one for each stack) or you could try one MAF on one stack. I think the Megasquirt will certainly let you do one MAF on each side of the engine (total of two). I doubt it will support 8 MAF, but maybe so.

Or you could build a removable plenum to seal up to the 8 stacks and have one opening to pull air through and put a single MAF there. If so might as well pipe it to a cool air source while your at it.

You are right Olddog, brain fade, I wasn't thinking! The air box work would be prohibitive. This is an example of where speed density is a much better fit.

Ed

[olddog]

Originally Posted by ERA 626

When I told Dave I wanted these numbers he called me stupid and ignorant.

1.25 Hp/CI is not stupid and it is done all the time. So the next question is, why does he think it is stupid and ignorant?

Maybe he thinks the engine manors on the street will suck. It takes really good heads to get there without a radical cam.

Maybe he thinks the choices of parts will not work well together. Radical cams and 8 stacks do not play well together.

Basically I think the conversation ended too soon.

Be ware of salesmen. They promise more than they can deliver every day to make a sale. That is there job. They will even tell you they love you if you want them to. After the sale they disappear. Kind of what men do in a bar trying to pick up a one night stand.

[olddog]

Originally Posted by eschaider

You are right Olddog, brain fade, I wasn't thinking! The air box work would be prohibitive. This is an example of where speed density is a much better fit.

Ed

Correct me if I'm wrong, but speed density also does not handle radical cam profiles, as well.

600 HP with a single carb on this engine, no problem. Putting on the 8 stack with speed density and wanting it to drive nice and friendly may be a challenge. I know there are plenty of people on this site who have done some of this work in the past. I didn't follow it closely, nor can my mind retain things well at this stage of life.

I know in theory single pipes into the cylinders and single pipes out of the cylinders should allow a radical cam to idle smoothly, as the reversion flow from one cylinder does not disturb other cylinders. However back in the real world, the reversion air flow is pushing fuel laden air out the horns, causing an explosive haze to hover over the engine with webbers. Then the fuel laden air is sucked back through the webber again making it near impossible to get the AFR correct. So getting these engines to run well at lower rpms requires milder cam profiles.

The short air path of a nice 8 stack lends itself to high rpm air flow, but at the same time requires a cam profile that does not help high rpm air flow. This is where super good flowing heads come into play. Good heads do not require as radical cam profile to flow at higher rpms. I'm not certain there are tons of heads for the FE that will do that. I'm not saying the combo cannot be found. However this is not likely to be a easy case of tossing parts together and getting it to work.

[eschaider]

I believe the issue with the more aggressive cams is lobe separation angle (LSA) and idle reversion you were speaking to earlier that it fosters, Olddog. Lobe separation angles between 104˚ and 108˚ or so come with significant overlap especially with the longer duration cams.

That overlap and the low speed idle reversion is what provides the nasty idle sound that is so sought after by many. It also produces an engine with relatively bad low speed manners below 2000 rpm or so. The EFI helps some in alleviating the issue because the fuel delivery is no longer contingent upon a vacuum signal from the cylinder. On the other hand, while the particular cylinder is reversing its flow up the intake port, it will necessarily drag some fuel with it leaning out that particular cylinder.

During the next intake event there will be some of the fuel that never made it into the cylinder from the last induction cycle and it will be mixed with a full charge of fuel for this cycle (less some for reversion again). The upshot is the cylinders get a raggedy inconsistent supply of idle fuel and air that produces the raggedy idle (that every one likes) with the attendant bad low speed manners (that get old quickly).

Plumbing the intake ports together with a heat resistant tubing on the valley side of the intake manifold can mitigate a lot of the negative pressure pulses but will not eliminate them entirely. As a result once again we have a bad mannered low speed performance but not as bad as before the plumbing was put in place.

Tight LSA's reproduce the sound of the 1960's race versions of the engine remarkably well. They just force you to operate the engine above the ratty idle rpm range so the car drives better around town. EFI (and hidden plumbing) can help to mitigate some of the mischief but it will not eliminate it.


Ed

[ERA 626]

Originally Posted by olddog

Correct me if I'm wrong, but speed density also does not handle radical cam profiles, as well.

600 HP with a single carb on this engine, no problem. Putting on the 8 stack with speed density and wanting it to drive nice and friendly may be a challenge. I know there are plenty of people on this site who have done some of this work in the past. I didn't follow it closely, nor can my mind retain things well at this stage of life.

I know in theory single pipes into the cylinders and single pipes out of the cylinders should allow a radical cam to idle smoothly, as the reversion flow from one cylinder does not disturb other cylinders. However back in the real world, the reversion air flow is pushing fuel laden air out the horns, causing an explosive haze to hover over the engine with webbers. Then the fuel laden air is sucked back through the webber again making it near impossible to get the AFR correct. So getting these engines to run well at lower rpms requires milder cam profiles.

The short air path of a nice 8 stack lends itself to high rpm air flow, but at the same time requires a cam profile that does not help high rpm air flow. This is where super good flowing heads come into play. Good heads do not require as radical cam profile to flow at higher rpms. I'm not certain there are tons of heads for the FE that will do that. I'm not saying the combo cannot be found. However this is not likely to be a easy case of tossing parts together and getting it to work.

Maybe I should explain more, The builder said it was "stupid" because I was thinking of building a 496 CI FE, We can easily do this with the 482 4.250 bore motor. The intake am having made is not really an 8 stack it is more of a cross ram with longer runners that start big and reduce down to the size of the port on the head. My builder has done several of these on SBF pantara projects they are amazing built by Moorison in New Zealand. He explains the port velocity being like a supercharger. The design includes a common vacuum plenum under the runners. Yes we will most likely loose the rumpy Idle (reversion) a little bummed about this.

This build is going into a Brand new CSX car.. The build will be as much fun as the drive...

[Anthony]

So what is the diameter of the ram tubes ?

Did you think about running either Hi-Riser or Tunnel port heads ?

[olddog]

Mike,

I am recover from Pneumonia, so my head is not right, yet. I only got an hours sleep last night. Enough about me.

I know the 482 is one of the most common strokers. I'm not sure if the extra 16 CI you are shooting for is stroke or bore increase. Frankly it doesn't matter a hole bunch how you get there. CID is CID, as long as you can fit big enough valves to make it breath. After that porting is everything.

The cross ram you describe is interesting. Guys have spent lifetimes perfecting pipe lengths to actually achieve a supercharge affect in a relatively narrow rpm range. The pipe length on both intake and exhaust matter. It can be very real and powerful.

I can talk in generalities. I don't know **** when it comes to the specifics. I do know that increasing the CID on a specific head, intake, exhaust, and cam setup causes the exact same thing to happen at lower rpm. To make it simple, if the only thing you changed on such a system was the CID say from 200 CID to 400 CID, and the 200 CID version made 200 Hp at 4000 rpm the 400 CID version should make 200 Hp at 2000 rpm at double the torque. The two engines should be ingesting the same amount of air, burning the same about of fuel, and making the same Hp.

This example seems upside down when you first here it, but when you think it through, it makes perfect since. A given intake, head and cam combo (exhaust too) pretty much are the main factors that define the air flow dynamic. Thus define the limit of the engine. Ok valve shrouding (bore diameter) would allow a bigger CID engine breath a tad better. Other than that factor, the peak Hp is pretty much set by the maximum air flow. The bore and stroke cause the rpm required to max out the induction system to change and the torque output to change. The bore and stroke do not change the Hp.

That all said, in reality the bore does limit the size of the valves that can be fit into the head. The valves absolutely limit the air flow. But in the case of your FE once you pick the head, this no longer matters.

I have no idea why the fellow objects to more CID. I cannot think of why 16 CID on a nearly 500 CID engine matters all that much to anyone one way or the other.

The only thing I can add is Chrysler experimented with a cross ram dual 4 barrel on a 426 wedge engine in the early 1960's. Each Carb set clean out over the exhaust manifolds on the opposite side of the engine that it fed. From a memory that is failing, I think the air reached supersonic speed in the mid to high 2000 rpm range. I saw several in station wagons. I believe they were trying to get the torque up at highway speeds.

Possibly he objects to more CID because you are move the rpm range down where the ram affect happens. Too many CID may put the peak affect of the cross ram so low in the rpm range that you will end up with stump pulling torque down low and loose all the ram affect so low that it just will not make the Hp.

Enough theory and speculation, assuming you haven't went to sleep.