Stealth Cylinder Head or Eddy's on a Stock Motor

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Stealth Cylinder Head or Eddy's on a Stock Motor

Post by Worker Bee on Sun Feb 15, 2015 7:48 am

I've wondered if anyone has put a set of these heads or Eddy's with the larger 2.14 intake valve on a stock motor (Magnum cam). I've had the impression that it may have a negative effect on bottom end power. Anyone have any thoughts or experience on this. Question

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Re: Stealth Cylinder Head or Eddy's on a Stock Motor

Post by Hemiroid on Sun Feb 15, 2015 8:00 am

Worker Bee wrote:I've wondered if anyone has put a set of these heads or Eddy's with the larger 2.14 intake valve on a stock motor (Magnum cam). I've had the impression that it may have a negative effect on bottom end power. Anyone have any thoughts or experience on this. Question
Can you give us more information on your motor, cu.in. cam specs, transmition, 4sp. or auto ect anything you can give will help.

Keny

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Re: Stealth Cylinder Head or Eddy's on a Stock Motor

Post by Worker Bee on Sun Feb 15, 2015 9:17 am

This would be for a "in the future" motor that would be going in a C body for a daily summer driver.
Building the motor for "quench and descent gas mileage is the main priority. It would have some type of automatic transmission with overdrive (Gear Venders).
Engine specs would be something like this:
440
Performer RPM intake
Some type of fuel injection???
Headers with 2 1/2 mandrel bent exhaust
I was hoping to run it on 87 octane gas.
As far as the cam, I've personally driven a low compression 440 with a cam with these specs,
The Summit K6401 (a copy of an old name brand) It has a advertised duration of 282/292, 0.465"/0.488" lift, duration at 0.050 is 224/234 duration, and the cam uses a wide LSA of 114 degrees, with overlap at 59 degrees. This car gets surprisingly good mileage considering that it has 3:55 gears.
An aluminum head with 2.08 intake valve would be ideal, but no one makes one as far as I know.

Angelino

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Re: Stealth Cylinder Head or Eddy's on a Stock Motor

Post by 69ChargerR/TSE on Mon Feb 16, 2015 7:24 am

Remember when switching to Aluminum Heads, that the aluminum has the effect of dissipating the Heat of Combustion much faster.
Typically, for comparison purposes.... and depending upon current Camshaft & C.R. .... approx .5 to .8 pt more of static compression ratio is adviseable when switching to aluminum from cast iron heads, all things being equal of course.
The absolutely worst thing you can do, is to switch to Aluminum Heads from cast iron with Low Compression ratios like 9.0:1 and lower. That can be a complete waste of time !
The 2nd issue of course, when switching to Aluminum Heads with small Camshafts, can be the port CC Volume as it relates to A/F speeds for Torque ?
research first..... changes from knowledge.

Google "Dynamic Compression ratios" as it relates to effective cylinder pressures, with a keen eye to "Aluminum" alloys effects.

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Re: Stealth Cylinder Head or Eddy's on a Stock Motor

Post by Worker Bee on Tue Feb 17, 2015 6:50 pm

I actually have read about Dynamic Compression before. I also read that Quench is really important if I want to run this motor on lower octane gas. The main reason I'm considering the Stealth or Eddy head is because they are aluminum and will help with me raising the compression ratio compared to the iron heads.
I guess I'll have to do some research on port CC Volume as it relates to A/F speeds for torque...........good point, thanks!   study

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Re: Stealth Cylinder Head or Eddy's on a Stock Motor

Post by AJ/FormS on Fri Oct 09, 2015 5:15 am

Keep in mind that a C needs torque to get it moving. You can build that torque into the engine, or crutch it with gears and hi-stalls.It really depends on what you want it to do at the other end. For a streeter, that rarely exceeds 65 mph or so, High-Rpm power is not a big deal, cuz then the top of first gear could well be speeding already.And to get into the powerband would require the crutches.
But for a streeter, that just wants to get moving in a hurry, and wants to cruise comfortably, you need to build for torque.And then if you do that, you may not need the GV.
This decision, useage, needs to be made first.Cuz it kinda dictates the TC and the gears, and the gas available.
Next you need to decide the power band requirement, which dictates the camshaft, which dictates the Dcr, which dictates the Scr, which dictates the total chamber volume, which dictates the piston and head chambers. And if aluminum heads are up for consideration, we go back and bump up the Dcr and start over.
For a streeter or a cruiser, aluminum isn't always the best choice.
There is also a time that the GV is not the best choice. Say you build a combo that makes peak vacuum at 2800 rpm(big cam), there would be no fuel economy advantage to gearing it down to force the engine to run at 2200rpm, where the vacuum might be considerably less. In this case the engine will still be in reversion, and economy might get considerably worse. Granted, cruising at 2200 is much more pleasant, and wear and tear may be less.Unless the reversion characteristics cause the engine to run very rich, in which case bore and ring wear, among other things, may be affected.
The 440 has by it's very design, a strong leaning to make torque. If you exploit that,your C will be a pleasure.
A small block(that's all I'm familiar with), will burn 87E10 for 100,000 miles and more, with a Dcr of 8.6 to 8.8, AND aluminum heads. It will take near full timing as early as 2800@ 900 ft elevation (that's my combo).
I freely admit that I have very limited experience with BBMs, but if pressed, I see no reason that a fast rate of lift cam of about 228* at .050 will get your C moving in style.  With a tight quench, an engineered Dcr,and a sharp tune,(including the vacuum advance) it will also return very good fuel economy, without the GV. It will do that with 3.55s and tall tires. The small cam will like a dual plane, and a small DP carb. The tight quench, while desirable, will not be a huge issue, however, it makes the Dcr easily attainable and returns excellent fuel economy.If you are not a floor-it-all-the-time kinda guy, I would push the Dcr envelope. For those times you know you are gonna be mashing it, either carry an octane booster, or move up a fuel grade or two, or slow down the advance curve, or reduce the air intake(smaller carb, or delayed secondaries) or run cooler.As for me,if I was in your shoes, I would really push the Dcr envelope.
Remember, the engine only needs enough octane to suppress detonation, under it's most stressed condition, that is max load. When you are cruising around, in a throttled condition, your effective compression ratio might be like 5:1, and might drink like 70 octane fuel, quite happily. The Static compression ratio assumes a cylinder is 100% full of air at atmospheric pressure. When cruising, it might only be 1/2 full of air. Well obviously it will be "full" of air, but only at partial atmospheric pressure. So if it's only "half" full,the pressure will be way down, and so will be the tendency towards detonation. A higher Static compression ratio, will increase the efficiency of the cylinder,leading to more work getting done,on the same amount or less of fuel, and yet not exceeding the octane of the fuel.
You can kinda get an understanding of this during a compression test. This test is usually done by blocking the carb butterflies at WOT. This is because it will require the least number of compression cycles to achieve it's highest reading. If the test was to be repeated, with the butterflies all closed, it would take several more compression cycles to achieve it's max reading. Furthermore, it can be clearly seen in the progression of the compression cycles. Whereas at WOT, the first 2 cycles might make 60% of max, when throttled, it will be very significantly less. When I do a compression test, I always record the progression. If I see 7 cylinders make 90 psi on the first event, and the eighth only makes 70 on the first event, Ima keeping an eye on that one.  Or if one takes 2 more cycles, Ima asking why.

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Re: Stealth Cylinder Head or Eddy's on a Stock Motor

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