Chat: Eddie FourFather Hill Atom II Ecotec Performance Upgrades

[FourFather]

Hi, and welcome to the Discussion thread about my Atom upgrades. Please post any questions or comments here, so we can keep the Upgrade thread clean enough to be useful to anyone who cares to refer to it. Thanks for your cooperation in this.


Eddie

[Driver]

Good start on the build Eddie. :TU:

Very nice of you to take the time to catch us up on what you've already done to chase those elusive seconds down as well. I know it may be strung out over other threads but the build thread encapsulated it all back into one place. Looking forward to see the build progress and the pictures as you get elbow deep into it.

[1965Cobra427]

Hi Eddie - I enjoyed our chat today on the phone and find it interesting that we have some of our upgrade plans in common. I'm going a couple notches back from you, but hope to at least keep you in sight at the track. I'm looking forward to additional installments on your build thread.

If things work out, I'll see you at Hallett on Saturday. Can't wait to see/hear the Ultima going 'round the track!

[FourFather]

Hi, Randy,

Good to talk to you, too! It does sound like we're doing similar mods- I bet we're gonna have BIG fun!

I cancelled my plans for Hallett for day after tomorrow because of the weather forecast. Even if it is dry, and that is a big if, I don't think the track is going to be warm enough to do much good.

Will winter EVER give up?

Eddie

[Heywood-Yablowme]

Eddie,will you be deleting the balance shafts,or running neutral balanced ones? What cams are you going with? Are you going to stay with the GM engine management? The Ecotec really is a sweet 4 banger!

[FourFather]

[quote="MadMaxAtom and company"]
Eddie,will you be deleting the balance shafts,or running neutral balanced ones? What cams are you going with? Are you going to stay with the GM engine management? The Ecotec really is a sweet 4 banger!
[/quote]

I don't plan to do a complete delete, because I want to run the standard water pump. I'm thinking about cutting the standard shafts off just past the front bushing that will leave just enough of the shaft at the front to locate it and work properly with the standard bushing/and sprocket. And then make a couple of light-press-fit sleeves to fill the rear bushing to stop the oil flow. But I haven't really looked at that much yet and haven't made that call for sure.

Comp Cams is doing a pair for me but they are not here yet. More on that after they arrive.

I'm planning to use the GM ECU and tune it with my HPTuner. I'm on my twenty-second tune so far, and so far there hasn't been anything that I wanted to do to the tune, that I haven't been able to do.

The engine is very nice! Very Sportbike-like!

Eddie

[Terry Kennedy]

[quote="FourFather"]
I'm planning to use the GM ECU and tune it with my HPTuner. I'm on my twenty-second tune so far, and so far there hasn't been anything that I wanted to do to the tune, that I haven't been able to do.[/quote]

In your build thread, you posted this graph:

[quote="FourFather"]
[/quote]

Was that the "factory" (Brammo) tune? Do you know if your car ever got the updated ECU code?

Here's what my Atom (Brammo "300 HP" with the "fix") did, on 91 octane fuel:



That was before I changed the factory exhaust for the HyTech one.

[silver]

the dyno with the huge drop at 5800 rpm is Eddie's car running Darth's tune that Eddie modified further then started over again and redid the tune to get the curve smooth as a baby's bottom

FWIW on darth's car that drop didn't occur but it does occur on my car running the same tune.

Eddie and I both tried Darths' tune but it didn't work in our cars, I think this might be more evidence that you really need to tune each atom individually so that you can make sure it's good to go.

[DarthChicken]

A big part of that problem was a learning curve on my part, with the software.  That, and they are just Texas cars 

Eddie - here is the link to the  balance shaft delete kit I'm using.  I've had it on my car for probably close to 10k miles, no issues except that my passenger rear fender vibrates like crazy at idle, and I had to rubber isolate my mirrors because the vibration was bad enough that it made it hard to see what was behind me.

http://levelzeromotorsports.com/store/product_info.php?products_id=50&osCsid=173db029b7f1dd0b955127bab28ff9fb

[NormLarson]

Darth would you do the delete again?  Were the extra RPM's worth the vibration increase to you?

[DarthChicken]

I have not done valve springs (yet).  I was holding off on those, because I wasn't sure if I wanted to do cams as well.  So, I still rev to 7200rpm.  All I've done is add vibration to my setup. 

[Heywood-Yablowme]

I found this very enlightening;

"With any engine balance is important, especially for high rpm operation. It’s a common misconception that the balance shaft is used to balance the engine. It is not. An engine’s rotating assembly is balanced so that when the crank is spinning in a circle the weight at any one point is the same. This makes it so that no uneven forces to try and move the engine in a particular direction at any point in it’s rotation. Hence the spinning is ‘in balance’. A great example is a tire. Have you ever had tire shake or driven a car before the wheels were balanced? Same thing. These forces at high rpm turn into a vibration which literally shakes your engine apart. In a motor, you add or remove weight from the crank, make sure the rods and pistons weigh the same. You make sure that the balancer and fly wheel are both ‘in balance’. The better the balance, the higher the rpm the engine will survive at.

Consider the math. An imbalance of one ounce (the weight of a rod bolt) 1” away from center at 2,000 rpm will be subjecting a force of 7 lbs. At 4,000 rpm, the force grows to 23.5 lbs! Double the speed again to 8,000 rpm and the force becomes 114 lbs! Keep in mind, this is one 1” away from the center of rotation. The idea is to show why balance issues are negligible at low rpm but insanely important at high rpm.

The Ecotec engine has 4 cylinders, they move in pairs. Two go up while 2 go down. The design of the 4 cylinder engine lends itself to a shake at idle. This shake is not to say the engine is not balanced, it is. The shake comes at the moment the cylinders change direction. The ones moving up change direction to go down and the ones going down change direction to go up. This creates a slight shock that is felt as engine shake. As the engine speed rises, so does the frequency of this shock and it’s not felt much as it’s absorbed through the mounts and chassis. A good example of this is a subwoofer vs. a tweeter. Bass is low frequency sound and you can hear it for a long ways, it shakes your car. But no one ever complains about a neighboring cars mids or tweeters because higher frequencies do not travel as well or shake other objects. Same principal.

The balance shafts are actually out of balance rods that create a vibration. This is done on purpose to cancel out the vibration inherent to a 4 cylinder engine. Mainly they do their work at idle and low engine speeds where vibrations are felt the most. They do not keep your engine in balance; in fact they are purposely out of balance which is bad for performance. This trade off is worth it for the average consumer. The real problem comes when you want to use the engine at high engine speeds. Remember the math above about forces as they relate to rpm? It just so happens that the radius of a factory balance shaft is just over an inch but the out of balance (counter weight) is a lot more than an ounce! This translates to terrible internal engine shake and HP being used to create this vibration. For high rpm engine operation, it is essential to eliminate the factory balance shafts or run neutral shafts which can spin at any speed without causing any vibrations."

ZZ performance sells these neutral balance shafts for $275.

Jesus....22 tunes and counting...   I had better look into HPtuners.

[silver]

question, why don't you just do a balanced crankshaft and not worry about the rest of it.

Only reason I ask is in my ignorance back in the day I had a honda where I did the balanced crank along with every other internal engine mod available, so I am still under the impression that you can balance a crank for any car, is this not true?

[Heywood-Yablowme]

No matter how well you dynamically balance a crankshaft and all the rotating mass,you will always have an inherent unbalance in 4 cyl engines.That's just the way it is. A V8 is not smoother because of all those extra cylinders,it just happens to have a more neutral firing balance because of the design.
Think of it like this...you can balance a square wheel..just don't try to go anywhere on it.

All factory crank and rotating assemblies are balanced to a degree of about 1/2 oz. (14 grams)  Custom balancing takes it a bit further,down to the 1/10th of a gram.

[DarthChicken]

[quote="MadMaxAtom and company"]
I found this very enlightening;

"With any engine balance is important, especially for high rpm operation. It’s a common misconception that the balance shaft is used to balance the engine. It is not. An engine’s rotating assembly is balanced so that when the crank is spinning in a circle the weight at any one point is the same. This makes it so that no uneven forces to try and move the engine in a particular direction at any point in it’s rotation. Hence the spinning is ‘in balance’. A great example is a tire. Have you ever had tire shake or driven a car before the wheels were balanced? Same thing. These forces at high rpm turn into a vibration which literally shakes your engine apart. In a motor, you add or remove weight from the crank, make sure the rods and pistons weigh the same. You make sure that the balancer and fly wheel are both ‘in balance’. The better the balance, the higher the rpm the engine will survive at.

Consider the math. An imbalance of one ounce (the weight of a rod bolt) 1” away from center at 2,000 rpm will be subjecting a force of 7 lbs. At 4,000 rpm, the force grows to 23.5 lbs! Double the speed again to 8,000 rpm and the force becomes 114 lbs! Keep in mind, this is one 1” away from the center of rotation. The idea is to show why balance issues are negligible at low rpm but insanely important at high rpm.

The Ecotec engine has 4 cylinders, they move in pairs. Two go up while 2 go down. The design of the 4 cylinder engine lends itself to a shake at idle. This shake is not to say the engine is not balanced, it is. The shake comes at the moment the cylinders change direction. The ones moving up change direction to go down and the ones going down change direction to go up. This creates a slight shock that is felt as engine shake. As the engine speed rises, so does the frequency of this shock and it’s not felt much as it’s absorbed through the mounts and chassis. A good example of this is a subwoofer vs. a tweeter. Bass is low frequency sound and you can hear it for a long ways, it shakes your car. But no one ever complains about a neighboring cars mids or tweeters because higher frequencies do not travel as well or shake other objects. Same principal.

The balance shafts are actually out of balance rods that create a vibration. This is done on purpose to cancel out the vibration inherent to a 4 cylinder engine. Mainly they do their work at idle and low engine speeds where vibrations are felt the most. They do not keep your engine in balance; in fact they are purposely out of balance which is bad for performance. This trade off is worth it for the average consumer. The real problem comes when you want to use the engine at high engine speeds. Remember the math above about forces as they relate to rpm? It just so happens that the radius of a factory balance shaft is just over an inch but the out of balance (counter weight) is a lot more than an ounce! This translates to terrible internal engine shake and HP being used to create this vibration. For high rpm engine operation, it is essential to eliminate the factory balance shafts or run neutral shafts which can spin at any speed without causing any vibrations."

ZZ performance sells these neutral balance shafts for $275.

Jesus....22 tunes and counting...    I had better look into HPtuners.
[/quote]

Max, that was probably the most insiteful, educational bit of information you've ever posted on this site.  Thank you very much, I had always wondered if doing the balance shaft delete was a good idea.. now I know it was.  And I learned something today, and its only 7:30 here!  

Silver - you can of course still blueprint the entire engine.  The balance shaft delete kit looks to be the first step in doing that.