Thread: Turbos and compression

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Here's a Final Compression Ratio Chart from Blower Drive Service. Static compression ratio is down the left side. Boost is across the top. Anything in the gray area will work with premium pump gas, like 9.0:1 with 6 lbs of boost. Anything in the white area will need E85, methanol, ethanol or racing gas.
Technical Charts

Although it is expensive, aftercooling (intercooling) will make a considerable difference, allowing more boost without detonation. So will water injection or alcohol injection. I used 70% Isopropanol alcohol from the drug store to good effect to prevent detonation with an Edelbrock water injection system several years ago. Mix a quart of 70% with a half quart of distilled water.

You can stay on top of this right out to the ragged edge by investing in a lighted 10X spark plug loupe and inspecting your spark plugs regularly.
http://www.speedwaymotors.com/Longac...-gMaAvAF8P8HAQ
Choose a place where you can make a full-out run 0-100 or so without encountering the law. A drag strip is the perfect place. Make your pedal-to-the-metal pass, then go to neutral and chop the ignition. If your ride has a steering wheel lock, cut the wire that goes to the coil and put an additional switch in the line that will allow you to cut power to the coil and still steer the vehicle. The whole point is that you don't want to do ANY additional driving or idling once you have made your banzai pass. Let the beast coast to a stop and pull the plugs for inspection right there on the spot. Of course, you will want to keep a strong flashlight with you for pulling plugs at night if you have to.

Detonation will first show up on the insulator of the plug as little black specks, looking like someone sprinkled black pepper on the insulators. This would be engine oil that was squished out from the top piston ring groove when detonation delivered its sledgehammer blows to the crown of the piston. If you let that condition go unchanged, the next thing you will begin seeing on the porcelain is little silver specks. That would be the pistons melting.

http://www.4secondsflat.com/Spark_plug_reading.html
https://www.ngksparkplugs.com/about-...d-a-spark-plug
http://www.dragstuff.com/techarticle...ark-plugs.html
http://www.nightrider.com/biketech/readplugs.htm
http://racingsecrets.com/spark_plug_reading.shtml
http://www.biblio-moto-books.net/mot...t/sparkplg.htm

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Originally Posted by techinspector1

Here's a Final Compression Ratio Chart from Blower Drive Service. Static compression ratio is down the left side. Boost is across the top. Anything in the gray area will work with premium pump gas, like 9.0:1 with 6 lbs of boost. Anything in the white area will need E85, methanol, ethanol or racing gas.
Technical Charts

Aftercooling will make a considerable difference, allowing more boost without detonation. So will water injection or alcohol injection. I used 70% Isopropanol alcohol from the drug store to good effect to prevent detonation with a water injection system several years ago with an Edelbrock system. Mix a quart of 70% with a half quart of distilled water.

Now that is a helpful chart!

Originally Posted by techinspector1

Although it is expensive, aftercooling (intercooling) will make a considerable difference,

So will water injection or alcohol injection. .

I think I will have room for an air/air inter-cooler. I even have one left over from the diesel.

I have bought water/alcohol injectors for my two diesels but have not yet installed them; it is tough finding a place to carry water.

The only experience with adding a turbo I have is with my one diesel 7.3 IDI in a 9K# van. On that one it made a huge difference, and it has never made 10# of boost. I also have a 2001 Power Stroke in an 11.7K# van, and it can make about 15#.

The vehicle is being set up as a tow vehicle. It will probably never see 5K rpm. The turbos I have supposedly come in early. Can I be expected to notice 5# boost?