Author Topic: Forced Induction for 440/512  (Read 3384 times)

Offline Spartan040

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Forced Induction for 440/512
« on: September 20, 2015 - 09:15:45 PM »
I'm reconsidering adding forced induction to my planned 440/512 stroker. Say for instance I have an A518 transmission, a 440/512 lightened with aluminum parts, EFI, headers, Voodoo cam with a custom grind, and the properly ported heads. Chryco, you said the engines like this that you built got around 18-20 mpg and about 400 whp? How much power would I gain, and would I lose any fuel mileage, if I decided to build it for lower compression and put on either a turbo, twin turbo, or say, an F2 Procharger? Pros and cons to those different systems? I also thought about compound boost, using some sort of turbo setup and a supercharger. Thoughts?




Offline Chryco Psycho

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Re: Forced Induction for 440/512
« Reply #1 on: September 21, 2015 - 01:18:27 AM »
I prefer turbos , they seems to be more efficient both for power & milage , you could make 40% more power though , I have seen twin turbo 440s making over 1000 hp .

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Offline cudabob496

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Re: Forced Induction for 440/512
« Reply #2 on: September 21, 2015 - 03:47:59 AM »
would think with forced induction, you would be totally overpowered for the street.

a normal induction 512, well built, could make at least 700 hp I would think. And that
is barely usable on the street.  I have at least 600 hp, and if I used it often,
I may need someone to bail me out of jail.
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

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Offline Spartan040

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Re: Forced Induction for 440/512
« Reply #3 on: September 21, 2015 - 01:09:48 PM »
I wasn't going for a super overpowered build, the only reason I was considering forced induction was that Chryco said the (somewhat) fuel efficient 440/512's he built were making 650 gross and only 400 at the wheels. I was looking to end up somewhere around 550-650 at the wheels

Offline Chryco Psycho

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Re: Forced Induction for 440/512
« Reply #4 on: September 21, 2015 - 03:06:44 PM »
have you ever driven 600 at the wheels or is this just a number??

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Offline Spartan040

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Re: Forced Induction for 440/512
« Reply #5 on: September 21, 2015 - 03:59:11 PM »
have you ever driven 600 at the wheels or is this just a number??

Closest Ive gotten was 485 in that scat pack Challenger, so it's just a number. That's why I said 550-650

Offline moper

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Re: Forced Induction for 440/512
« Reply #6 on: September 25, 2015 - 05:15:13 PM »
Efficiency comes from the build. Boosted engines must have more fuel when making their power, even under light boost. So the question becomes if you had to make the choice between power and economy where would you be? This of course ignores value, otherwise known as the cost to get there.
Supercharges run off the engine and use a good percentage of power up turning themselves. The turbos don't use any power which is why they typically show much more power at the crank. Also, because hte blower is off the crank, it stresses the front of the block and crank a bit more. So that also can limit your output. The blowers are more cost-effective (read as cheaper) to get in and running because custom manifolds are required for turbos. Intercoolers are a good idea for both. In your case it seems to me to be a lot of expense to run boost at levels you can reach naturally aspirated.
Point of fact - the last 496 I built makes 440 (dyno'd by the owner - not me) to the tires, through factory manifolds and full exhaust,  and gets 14 mpg. That's on pump 91w/10% ethanol, a solid flat tappet, and having one 1st in Stock appearing at Carlisle. He's driven it on several occasions over distances including CT to PA for Carlisle, and CT to NY state for shows and it's got a 2500 convertor and 3.23s. His plans include headers and a larger carb and I'm fairly certain it will get past 460 at the tires. That's close to 550 at the crank with a cam under .600 lift that looks like a stock 383 with bolt ons.

Offline GreenFish

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Re: Forced Induction for 440/512
« Reply #7 on: September 29, 2015 - 07:56:52 AM »
Not that I have a high HP turbo or SC car but...

My understanding is that one of the benefits of a Turbo is the streetability along with high HP. Especially if the turbo has more lag. If the boost is not spooled up the power isnt there so if you are just cruising through a parking lot or stop and go traffic you are manageable.

70 cuda, 440, KB pistons, 10.5:1 compression, edlebrock heads,RacerBrown cam, 5-Speed Tremec, Megasquirt EFI

Offline Spartan040

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Re: Forced Induction for 440/512
« Reply #8 on: September 29, 2015 - 09:36:02 AM »
Not that I have a high HP turbo or SC car but...

My understanding is that one of the benefits of a Turbo is the streetability along with high HP. Especially if the turbo has more lag. If the boost is not spooled up the power isnt there so if you are just cruising through a parking lot or stop and go traffic you are manageable.

True, although to my understanding they've gotten quite good recently at really minimizing the lag, so it acts more like a supercharger. Overall, if I do go forced induction, I think I like the supercharger idea. They're generally more reliable (I've heard), it will produce the power I need without going overboard (a turbo would probably do too much) and it's an American car, supercharging is an American thing, they belong together  :wavingflag:

Offline HP_Cuda

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Re: Forced Induction for 440/512
« Reply #9 on: September 29, 2015 - 02:00:02 PM »

There are trade offs. I like using Blowers but they have parasitic drag while Turbos are known as "free hp" they also have drawbacks in the form of forcing hot exhaust into your intake. Additionally most folks who run turbos now use intercoolers to try and mitigate the heat and have a heck of a time finding a spot to mount them as they are not tiny. Lag time with turbos still exist although not like the 80's where they were almost 3-4 seconds, whereas Blowers have immediate response. If you ever watch someone start a car with a Blower they barely have to use the starter because it starts very quickly and that is because of the almost instant atomization of the fuel. You can actually get good gas mileage with a Blower as long as you take it easy with the fun pedal.

Use what you like and enjoy.  :burnout:
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Offline Strawdawg

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Re: Forced Induction for 440/512
« Reply #10 on: September 30, 2015 - 11:40:18 AM »
Turbo lag should be virtually non-existent when the turbo size is properly selected and matched against the engine combo and torque converter.  Normally, on a properly configured car, the problem is in moderating the boost increase in order to keep the tires hooked.

Both belt driven superchargers and exhaust driven turbos heat the air.  How much depends upon the compressor map of the unit and where the unit is operating within the map.  Nothing is free.  The idea behind forced aspiration is to force more air molecules into the cylinder which compressing the air does.  On the otehr hand, the hotter the air becomes, the further apart (less dense) the charge will become.  So, we use intercoolers to help lower this temperature to maximize charge density, and for those of us that like boost and don't want to run race gas, we use alcohol injection which reduces charge temperature thru vaporization.

On days when the ambient air temperature is 100+ degs, I see inlet temps into the plenum in the 90 deg range. 

Moreover, turbo wheel design has evolved steadily since the mid-80's.  Add ball bearing units which allowed us to drop the converter stalls by 800 rpm or so over journal bearing units and obtain the same spool up and it's difficult to tell a properly done car from a naturally aspirated car other than the amount of power pulled out of a given engine size other than the difference in sound and the much better drivability that results from a much milder engine combo.

The downside as mentioned is cost for the exhaust plumbing if the car did not come from the factory with a factory turbo.  On larger engines where two smaller turbos often provide better streetability than one large unit, this is an even greater problem.  And, as mentioned, some cars have less room for a big IC than others, but, even a small IC with alky injection will work very well for a street car.

Turbos, or superchargers, both really need fuel injection to maximize performance, and simplify tuning.  I am down to two turbo cars now from four.  My most massaged one will run close to 130 in the quarter but will pull 23 mph on cruise control with the AC turned on.  Yet, it drives around town like your grandmothers Buick with no hesitation at all.  Gas pedal feels like it is directly attached to the rear tires and there is no lag.  It's all about combination and understanding how to tweak the tuning. 

Offline Spartan040

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Re: Forced Induction for 440/512
« Reply #11 on: September 30, 2015 - 09:05:04 PM »
Turbo lag should be virtually non-existent when the turbo size is properly selected and matched against the engine combo and torque converter.  Normally, on a properly configured car, the problem is in moderating the boost increase in order to keep the tires hooked.

Both belt driven superchargers and exhaust driven turbos heat the air.  How much depends upon the compressor map of the unit and where the unit is operating within the map.  Nothing is free.  The idea behind forced aspiration is to force more air molecules into the cylinder which compressing the air does.  On the otehr hand, the hotter the air becomes, the further apart (less dense) the charge will become.  So, we use intercoolers to help lower this temperature to maximize charge density, and for those of us that like boost and don't want to run race gas, we use alcohol injection which reduces charge temperature thru vaporization.

On days when the ambient air temperature is 100+ degs, I see inlet temps into the plenum in the 90 deg range. 

Moreover, turbo wheel design has evolved steadily since the mid-80's.  Add ball bearing units which allowed us to drop the converter stalls by 800 rpm or so over journal bearing units and obtain the same spool up and it's difficult to tell a properly done car from a naturally aspirated car other than the amount of power pulled out of a given engine size other than the difference in sound and the much better drivability that results from a much milder engine combo.

The downside as mentioned is cost for the exhaust plumbing if the car did not come from the factory with a factory turbo.  On larger engines where two smaller turbos often provide better streetability than one large unit, this is an even greater problem.  And, as mentioned, some cars have less room for a big IC than others, but, even a small IC with alky injection will work very well for a street car.

Turbos, or superchargers, both really need fuel injection to maximize performance, and simplify tuning.  I am down to two turbo cars now from four.  My most massaged one will run close to 130 in the quarter but will pull 23 mph on cruise control with the AC turned on.  Yet, it drives around town like your grandmothers Buick with no hesitation at all.  Gas pedal feels like it is directly attached to the rear tires and there is no lag.  It's all about combination and understanding how to tweak the tuning.

I was definitely planning on going fuel injection. How does alcohol injection work?

Offline Chryco Psycho

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Re: Forced Induction for 440/512
« Reply #12 on: September 30, 2015 - 10:10:07 PM »
Don't tell the guys with Cummins engines or highway rigs that turbos are unreliable 1,000,000 miles working hard most of their life is possible  if you do not shut them down hot & keep the oil & filters clean

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Offline Strawdawg

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Re: Forced Induction for 440/512
« Reply #13 on: September 30, 2015 - 10:24:29 PM »
Remember that it will be expensive due to the better performance out of two turbos on that engine size...

It all started with water injection..then water/alcohol mixes, and we use 100% for most power. 

In WWII they used a mix for supercharger power at high altitude in P-51's and such.  Kept the engines from blowing the heads off under emergency power.

It is based on latent heat of vaporization.  When a liquid is converted to vapor, the process removes heat from the surrounding environment which results in a temperature drop.

Straight water results in the largest drop altho alcohols are pretty efficient as well.  Think about wiping rubbing alcohol on your arm.  Remember how cool is as it evaporates?  Or, if you live in a low humidity area, how well evaporative cooling works...

50-50 water and alcohol is quite popular because it is not flammable and the alky provides some fuel content to the mix whereas water only provides cooling.

100% methanol provides good cooling but it also provides a high octane fuel source to accompany the cooling benefit.  One would not want to have a rupture in the methanol tank because it would make a really nice fire.  Methanol produces less heat than gasoline but it gives a lot more than waterr :)

Now, what does the cooling do?  When we mist the injection fluid into the pipe going to the throttlebody, it immediately flashes into vapor and dramatically drops the temperature of the charged air going into the engine.  This means one can run considerably more boost without detonation.  (when we spray gasoline into the engine, it also vaporizes and cools the combustion chamber temperature...that is why richer mixtures tend to reduce detonation.  Spraying water, water/alky, or straight alky further reduces the temperature which allows us to run more boost without detonation.

For the record, detonation is the auto combustion of the end gases in the combustion chamber.  It is not the same as pre-ignition.

When the spark plug fires, the air/fuel mix is ignited in the area around the plug tip and the flame front ideally spreads smoothly across the top of the piston and develops a smooth increase in combustion chamber that peaks after top dead center and drives the piston down.

If, after the air/fuel mix has been lit, the gases around the edge of the cylinder spontaneous ignite instead of waiting to be lit by the spreading flame front, we get a sudden pressure spike and a sound that can resemble a hammer hitting the piston....it is harmful, but normally it spikes as the piston goes over top dead center so it is not nearly as bad as pre-ignition.  Still it, can blow the head gaskets apart, hammer the bearings, and/or break rings...On a normally aspirated car, it is not good at all, but on a forced aspirated engine, it is multiplied many times.

Pre-ignition, of course, is ignition caused by something other than the spark plug.  A hot spot in the combustion chamber sets off the air/fuel mix before the plug fires.  This means the piston is low in the chamber and it tends to reverse the direction of the piston travel which can end up with a lot of broken stuff including the crank. 

Now, we have run water injection on normally aspirated cars for years when we had high compression and too low an octane gas.  I know several people who currently run Snow Performance's kit on their cars so they can run a bit more timing with their choice of gas.  It works, but does not enable the increase in power that it does on forced aspiration.

On my Buicks, I can run about 17 psi of boost on 93 octane.  With alky, I typically run about 26 psi on 91 octane and sometimes when I am serious 28 psi.  This gives me more than 100 hp on a 231" engine.

Alky Control probably makes the best kits for forced aspiration.

Offline Strawdawg

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Re: Forced Induction for 440/512
« Reply #14 on: September 30, 2015 - 10:28:08 PM »
Don't tell the guys with Cummins engines or highway rigs that turbos are unreliable 1,000,000 miles working hard most of their life is possible  if you do not shut them down hot & keep the oil & filters clean

Turbos are very reliable, for sure.  I had 50,000 miles on the original turbo on my first Buick before I swapped it for a bigger one...clean, cool oil is the secret.  Most of the ones I have seen bad were due to the engine spitting metal into the exhaust wheel altho I am sure there are some that were not built right that fail.