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Old 09-18-2011, 03:23 PM   #4 (permalink)
oil pan 4
EV convert
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Join Date: Jul 2011
Location: NewMexico (USA)
Posts: 9,428

Sub - '84 Chevy Diesel Suburban C10
90 day: 19.5 mpg (US)

camaro - '85 Chevy Camaro Z28

Riot - '03 Kia Rio POS
Team Hyundai
90 day: 30.21 mpg (US)

Bug - '01 VW Beetle GLSturbo
90 day: 26.43 mpg (US)

Sub2500 - '86 GMC Suburban C2500
90 day: 11.95 mpg (US)

Snow flake - '11 Nissan Leaf SL
90 day: 141.63 mpg (US)
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Its all about being able to hit a target temperature and pressure.
In a spark ignition engine you want to get your air fuel mixture as hot and under as much pressure as possible before lighting it with the spark plug.
If you get the air too hot the air fuel mixture could preignite and that would hurt fuel fuel economy and power.
Most vehicles in factory form stay well below that temperature and pressure preignition threshold.
This is one of those mods you really want to A-B-A test to make sure you dont hurt fuel economy.

The next gasoline engine I build I will get the temperature and compression into that ideal range by raising the compression ratio up to about 12:1, using a cold air intake.

A diesel engine is a little different. You always want a cold air intake, the diesels seem to respond best to cramming as much gaseous mass into the cylinder as possible. That is why deleting the EGR and running water mist injection works so well.
1984 chevy suburban, custom made 6.5L diesel turbocharged with a Garrett T76 and Holset HE351VE, 22:1 compression 13psi of intercooled boost.
1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 1LE drive shaft, 4th Gen disc brake fbody rear end.
2011 leaf SL, white, portable 240v CHAdeMO, trailer hitch, new batt as of 2014.
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