Engine engine engine

[cv2065]

I'm just teasing you...I know what you're talking about. That's a great article, too!

LOL. I'm picking up what you are putting down.

[Mike.Bray]

The issue I have is that the EFI systems stabilize the idle, removing some of the rumpety rump that I enjoy.

I'm not sure I agree with this. The only thing a carburetor can do at idle that fuel injection can't is puddle excess fuel in the intake manifold and screw up the idle. I'm running this cam and at 750 RPM it's lopey enough to shake the car but fuel and spark are precisely controlled.



I'm running 12 degrees advance at idle and AFR of 13:1 and it will "rumpety rump" nicely all day long.

[cv2065]

I'm running 12 degrees advance at idle and AFR of 13:1 and it will "rumpety rump" nicely all day long.

I'm not saying that you don't get one, it's just more of a controlled sound to my ears. This passage from the article speaks to it. Again, I'm not a pro tuner by any means and everyone is different as to what trade offs they prefer. I'm sure one day I'll upgrade to EFI which is why I built in the choice. But for now....

"The reality is that there are massive pressure waves bouncing around inside the manifold while the engine is running—made worse with a cam with lots of overlap. The carburetor “sees” these pressure changes which is another reason why the idle is unstable. With EFI, the huge swings in manifold pressure (or vacuum, if you will) will also be damped with a MAP sensor to make it easier for the computer to make a decision about how much fuel to deliver to the engine. This helps to calm the idle, making it more stable."

[Mike.Bray]

I'm not saying that you don't get one, it's just more of a controlled sound to my ears. This passage from the article speaks to it. Again, I'm not a pro tuner by any means and everyone is different as to what trade offs they prefer. I'm sure one day I'll upgrade to EFI which is why I built in the choice. But for now....

"The reality is that there are massive pressure waves bouncing around inside the manifold while the engine is running—made worse with a cam with lots of overlap. The carburetor “sees” these pressure changes which is another reason why the idle is unstable. With EFI, the huge swings in manifold pressure (or vacuum, if you will) will also be damped with a MAP sensor to make it easier for the computer to make a decision about how much fuel to deliver to the engine. This helps to calm the idle, making it more stable."

I really think we're talking about two different things here. The "rumpety rump" you like (we all like) is from reversion caused by when the incoming air columns are disturbed by pulse waves sent back into the intake manifold from the cylinders because the valves are opening and closing with wrong timing to the piston movement. Overlap from cam duration and lobe separation angle (LSA) is what causes this.

An engine can also "rumpety rump" at idle when it's not properly tuned, that is it's running rough or crappy as I call it. If the carb isn't properly tuned, refer to my pyramid of intellect, and/or the tiny idle circuits are getting gunked up from ethanol residue you will have a rough running engine at idle that sounds "rumpety rump". Of course changing to EFI with it's precise control of fuel and spark as well as high pressure fuel injection will make the engine run as it should be running. Fix the tune, remove the "rumety rump".

All is not lost though. Playing around with the LSA can restore the "rumpety rump" is you like but not without a cost.

A low LSA like 106 or 108 degrees will:
Move Torque to Lower RPM (which isn't bad for a street engine)
Increase Maximum Torque
Narrows the Power band
Increase Chance of Engine Knock
Idle Vacuum is Reduced
Idle Quality Suffers
Open Valve-Overlap Increases
Closed Valve-Overlap Increases

A high LSA like 112-114 degrees will:
Raise Torque to Higher RPM
Reduces Maximum Torque
Broadens Power Band
Decrease Chance of Engine Knock
Decrease Effective Compression
Idle Vacuum is Increased
Idle Quality Improves
Open Valve-Overlap Decreases
Closed Valve-Overlap Decreases

I'm running 114 degrees LSA since I'm running stacks on an IR intake. IR intakes do not like reversion at all and it really kills power and efficiency. My system is from Borla so it's not a true IR intake, there's a good size plenum under it that each runner is ported to. This plenum is for the MAP signal and also helps calm the system for better street drivability. In the old days we didn't have this so a MAP signal was too erratic and we had to run in Alpha-N mode instead of Speed Density mode.

As you saw in the video, even with my quasi-IR intake system, EFI, and 114 degree LSA cam I still have an impressive "rumpety rump" at idle.

[cv2065]

As you saw in the video, even with my quasi-IR intake system, EFI, and 114 degree LSA cam I still have an impressive "rumpety rump" at idle.

Agreed! Stacks are always awesome too!

[GoDadGo]

Back In The Day Mercury Was A Ford Product (Not Marine Propulsion Company) But Who Really Cares So Once Again Check Out This A Mercury SB4 7.0.

This one is in a Superformance which does produce some very interesting cars.

https://youtu.be/TDt6SKlENbY

[Ford & Jeep Fan]

351C as in 351 Cleveland. Can be stroked to 393 or even 408 with the stock block. take the same engine mounts and trans pattern as any other 302
These were What pushed Bill Elliot around the race tracks to record wins.

[bobl]

I really think we're talking about two different things here. The "rumpety rump" you like (we all like) is from reversion caused by when the incoming air columns are disturbed by pulse waves sent back into the intake manifold from the cylinders because the valves are opening and closing with wrong timing to the piston movement. Overlap from cam duration and lobe separation angle (LSA) is what causes this.

An engine can also "rumpety rump" at idle when it's not properly tuned, that is it's running rough or crappy as I call it. If the carb isn't properly tuned, refer to my pyramid of intellect, and/or the tiny idle circuits are getting gunked up from ethanol residue you will have a rough running engine at idle that sounds "rumpety rump". Of course changing to EFI with it's precise control of fuel and spark as well as high pressure fuel injection will make the engine run as it should be running. Fix the tune, remove the "rumety rump".

All is not lost though. Playing around with the LSA can restore the "rumpety rump" is you like but not without a cost.

A low LSA like 106 or 108 degrees will:
Move Torque to Lower RPM (which isn't bad for a street engine)
Increase Maximum Torque
Narrows the Power band
Increase Chance of Engine Knock
Idle Vacuum is Reduced
Idle Quality Suffers
Open Valve-Overlap Increases
Closed Valve-Overlap Increases

A high LSA like 112-114 degrees will:
Raise Torque to Higher RPM
Reduces Maximum Torque
Broadens Power Band
Decrease Chance of Engine Knock
Decrease Effective Compression
Idle Vacuum is Increased
Idle Quality Improves
Open Valve-Overlap Decreases
Closed Valve-Overlap Decreases

I'm running 114 degrees LSA since I'm running stacks on an IR intake. IR intakes do not like reversion at all and it really kills power and efficiency. My system is from Borla so it's not a true IR intake, there's a good size plenum under it that each runner is ported to. This plenum is for the MAP signal and also helps calm the system for better street drivability. In the old days we didn't have this so a MAP signal was too erratic and we had to run in Alpha-N mode instead of Speed Density mode.

As you saw in the video, even with my quasi-IR intake system, EFI, and 114 degree LSA cam I still have an impressive "rumpety rump" at idle.

Nice explanation Mike. To say this in a different way, EFI requires a wider LSA to keep the MAP sensor happy which is why efi engines idle smoother. You take a cam ground on a 106 lsa that idles raunchy, switch to the exact same cam ground on 114-116 lsa and it will idle pretty smooth.

Bob

[Mike.Bray]

Nice explanation Mike. To say this in a different way, EFI requires a wider LSA to keep the MAP sensor happy which is why efi engines idle smoother. You take a cam ground on a 106 lsa that idles raunchy, switch to the exact same cam ground on 114-116 lsa and it will idle pretty smooth.

Bob

You are correct! An "EFI cam" will almost have an LSA of 112-114 degrees.

[Mike.Bray]

I saw a friend of mine today that used to be the field rep for Fast EFI and talked to him about this article which he was familiar with. He had some interesting comments.

First thing he said was "All EFI does is fix the poor idle tuning of carburetion which makes carbureted cars idle like crap." He also added "There is a point to be made that efi does tame some of the lope... but it is lope caused by tuning inefficiency. Poor AF mixture.... wrong or erratic timing."

So nothing we haven't already said. But, he added that with EFI w/timing control you can dial in a split in timing in your idle cells and can induce more of a lope without screwing up the A/F ratio.

[GoDadGo]

How About This Little Engine That Only Makes 1,000 NA-HP and 876 LBS Torque?
I'm sure you could make it fit under a Super Snake Style Hood with a low profile air cleaner.

https://www.summitracing.com/parts/n...saAoK-EALw_wcB

Though this is technically BBC, since it has no distributor most folks won't know what it is.
You could stick a Blue Oval over the Bowtie Emblem on the intake and all would be right with the world.

Hummmmmmmm!!!!!!

[rich grsc]

Lipstick on a pig

[Mike.Bray]

How About This Little Engine That Only Makes 1,000 NA-HP and 876 LBS Torque?
I'm sure you could make it fit under a Super Snake Style Hood with a low profile air cleaner.

https://www.summitracing.com/parts/n...saAoK-EALw_wcB

Though this is technically BBC, since it has no distributor most folks won't know what it is.
You could stick a Blue Oval over the Bowtie Emblem on the intake and all would be right with the world.

Hummmmmmmm!!!!!!

I've seen one in person, they are HUGE and TALL! I have serious doubts you could squeeze one in a Cobra.

I would dearly love to have one, but not in a Cobra. My little 550 HP SBF is plenty.

[CW_MI]

I actually like threads like these. It brings in so many different opinions, all garnished from our individual past experiences. Sure, they are subjective, but for those that might not be as automotive savvy as others, it gives them things to think about an research. It even brings to light new things for us that have been around performance vehicles all our lives.

That being said. I just want something that sounds like this, it is music to my ears...Lol

https://youtube.com/shorts/chS4pr1Ak...-QtzJD6dLNhLIL

https://youtube.com/shorts/chS4pr1Ak...-QtzJD6dLNhLIL

[Ted G]

Partial to my naturally aspirated 427w. If you love tinkering and raw power with good reliability, this is for you.

IMG_8613 2.jpg IMG_8614 2.jpg

IMG_8615 2.jpg IMG_8616 2.jpg


IMG_8561 2.jpg

[Aleinsteingenius]

I put in my order today for a complete MKV kit. Going with a Godzilla engine. Stay tuned.

[Mike.Bray]

I put in my order today for a complete MKV kit. Going with a Godzilla engine. Stay tuned.

That sounds exciting. I did some design work for a Godzilla squeezed into a reproduction 68 Mustang, I can't imagine that big heavy beast shoehorned into a Cobra. I'll be following.

[Guardm16]

My dream engine would be a Prestige Small block 427 with the Jim Inglese Stack EFI. However, my budget would never get me there.

4947 dyno graphic 2.png
I love my Prestige 427. With the Sniper 2 EFI, it started on the first hit. Would have gone with stacks but; Budget and setup.
Installing 1.jpg

[Derald Rice]

There is a Godzilla FFR that shows up at our C&C in northern CO.

[Derald Rice]

Duplicate

[AC Bill]

Not very common any longer, but I don't regret, and have always enjoyed immensely, having an old school 5.0 donor engine.

[Nickjj]

I wanted the engine to look a little more traditional with the Cobra tin and the reliability of fuel injection with the Holley Sniper 2 and Hyperspark Distributer. 347 Stroker dynoed at over 400HP which is more than I would need for my driving ability. Also provided lots of room in the engine bay in the MK4.

Engine.jpg

[john42]

I wanted the engine to look a little more traditional with the Cobra tin and the reliability of fuel injection with the Holley Sniper 2 and Hyperspark Distributer. 347 Stroker dynoed at over 400HP which is more than I would need for my driving ability. Also provided lots of room in the engine bay in the MK4.

Engine.jpg

I have a Ford Racing 347 with Sniper 2/Hyperspark. We found on the dyno that, that air cleaner element was chocking the air at higher RPM. Swapped for a K&N 3inch tall version and remedied that. It was hard to dial in the AFR any thing over 4500 RPM with that small air filter.

The one I got: https://www.summitracing.com/parts/KNN-E-1963

[Mike.Bray]

I wanted the engine to look a little more traditional with the Cobra tin and the reliability of fuel injection with the Holley Sniper 2 and Hyperspark Distributer. 347 Stroker dynoed at over 400HP which is more than I would need for my driving ability. Also provided lots of room in the engine bay in the MK4.

Engine.jpg

That's a sweet setup for a MKIV.

[Nickjj]

I have a Ford Racing 347 with Sniper 2/Hyperspark. We found on the dyno that, that air cleaner element was chocking the air at higher RPM. Swapped for a K&N 3inch tall version and remedied that. It was hard to dial in the AFR any thing over 4500 RPM with that small air filter.

The one I got: https://www.summitracing.com/parts/KNN-E-1963

Thanks John, Well aware of the tiny filter element and the issues it causes. Did you have any clearance issue when the hood is on with the taller filter? I will be getting the one you recommended.

[rponfick]

See the recent Shoutout to Blueprint.
Ralph

[Takis31gk]

We are going with a Gen 3 Coyote in my MK5 build. IMG_6468.jpgIMG_6460.jpgIMG_6470.jpg IMG_6508.jpg

[Guardm16]

I wanted the engine to look a little more traditional with the Cobra tin and the reliability of fuel injection with the Holley Sniper 2 and Hyperspark Distributer. 347 Stroker dynoed at over 400HP which is more than I would need for my driving ability. Also provided lots of room in the engine bay in the MK4.

Engine.jpg

For those of you who have not tried the Hyperspark Distributor, Hyperspark ignition and Sniper 2. This is truly Plug and Play. The guide cap install tool for the distributor, sets the timing for you. The ignition controls the timing from there. So easy a caveman could do it.

https://www.youtube.com/watch?v=2JpH...cJCdgAo7VqN5tD