[DeTomaso] CR, Detonation, and water injection

[adin at frontier.net]

IMO, water/alcohol injection is NOT a substitute for intercooler.

Quoting "John Bentley (jab)" <jab at cisco.com>:

> Ken,
>
> I think the bottom-line is race gas is cheaper and requires no
> maintenance!  If you are running 11:1 or less CR,  race gas, normally
> aspirated, aluminum heads and 38 degrees or less of timing advance, I
> don't think you need to worry about detonation.  If you are running a
> turbo or supercharger, you'll see reduced cylinder head temps with water
> injection, but an intercooler is a better choice (IMHO).
>
> JB
>
>
> ________________________________
>
> From: Ken Green [mailto:kenn_green at yahoo.com]
> Sent: Wednesday, October 03, 2007 10:22 AM
> To: John Bentley (jab); detomaso at realbig.com
> Subject: RE: [DeTomaso] CR, Detonation, and water injection
>
>
> JB,
>
>     I was thinking about scenarios like Dennis running fast for 100
> miles.  I don't like the idea of dropping compression or retarding
> timing to avoid high RPM detonation because both reduce power and
> efficiency.  It looks like the only other simple approach seems to be a
> rich mixture to cool the chamber, but that's wasting gas, and if that
> goes too far, may require carrying more gas for a 100 mile run.  Since
> water has about 4 times the heat of vaporization of gas, it seems a lot
> better to add a small water tank and water injection than add to fuel
> capacity.  I know Dennis is going to EFI, so there is a possibility that
> the ECU can be programmed to control the water injection (I need to read
> the instructions that came with the TEC3r I bought).
>
>     I know water injection has been used in aircraft for years (I didn't
> realize on jets? do jet engines experience something equivalent to
> detonation?), but seems to have struggled to gain acceptance in the auto
> world.  I suppose the aircraft systems may be a lot more complex and
> expensive?  I assume water injection works a lot better in turbocharged
> applications where the issue is that the air has been greatly heated?
>
> Ken
>
> "John Bentley (jab)" <jab at cisco.com> wrote:
>
> 	All you need is a separate injection system for the water (like
> on a
> 	dc-8)! :)
>
> 	JB
>
>
>
> 	-----Original Message-----
> 	From: detomaso-bounces at realbig.com
> [mailto:detomaso-bounces at realbig.com]
> 	On Behalf Of Ken Green
> 	Sent: Wednesday, October 03, 2007 9:06 AM
> 	To: detomaso at realbig.com
> 	Subject: [DeTomaso] CR, Detonation, and water injection
>
> 	It seems to be common practice to use a rich mixture to cool the
> 	combustion chamber under high HP output conditions. I looked up
> the
> 	heat of vaporization of gasoline, and it's 135 calories per gram
> 	compared to 540 for water. This would suggest that you need a
> lot less
> 	water than extra gas to cool the chamber and it makes a lot of
> sense to
> 	use water injection to control detonation versus rich mixture.
> The math
> 	seems pretty simple.
>
> 	Ken
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