L20 blower motor?s

[NWOleman]

Ok guys i need some L 16, 18, 20 info. I want to put a blower on the L20 i had in the back of the wagon. What i want is a compression ratio of around 7.0 - 8.0 to 1. So i wanted rod lenghts on the motors and crank throws. I wonder what would be better, short rod length with a longer throw crank or longer rod length with a shorter crank throw? Thanks again guys, NWO.

[DISLEXICDIME]

go to this and read it

 

http://the510realm.com/PNphpBB2-viewtopic-t-407.html

[nismopu]

heres a link to kind of help out with the serpentine belt situation.

 

http://forums.hybridz.org/showthread.php?t=129093

[datzenmike]

Ok guys i need some L 16, 18, 20 info. I want to put a blower on the L20 i had in the back of the wagon. What i want is a compression ratio of around 7.0 - 8.0 to 1. So i wanted rod lenghts on the motors and crank throws. I wonder what would be better, short rod length with a longer throw crank or longer rod length with a shorter crank throw? Thanks again guys, NWO.

 

When you say blower, to me that means a super charger. And a good choice too as there is no 'turbo lag' with a s/c. Throttle response is immediate and at all RPMs.

 

For a normally aspirated motor, rod length/piston pin height/in relation to valve timing and port velocities are important and must work closely with each other to gain overall high RPM power. But for a forced induction motor a turbo or a s/c is a great equalizer. Air under pressure will flow past small valves, poor port shape, and mild cam. The motor doesn't have to struggle to inhale, it's being force fed. In fact too much valve overlap allows pressurized air fuel to flow right out past the exhaust valves anyway. Generally, a s/c will make a ho hum motor scream with little or few modifications.

 

Reducing the compression will rob you of low speed power and will require you to step into it more in the range where you do 90% of your driving. I would try to keep the stock compression and limit pre ignition with water injection or retarded ignition during boost conditions. Unless you are building a balls to the wall, race only motor.

 

As to rod/crank throw lengths. Crank throw lengths are for all intents fixed. Generally a longer stroke (not rod length) translates to an increased torque value. Rod lengths however, can be varied but the longer they are the shorter the piston pin height and visa versa. A longer rod length will cause the piston to reach maximum speed further down the bore than a short rod. I'm guessing that all things equal, this would absorb more energy from the combustion process on the power stroke. Cam timing changes also seriously affect this (and I'm way out of my area on this anyway) As I said earlier, forced induction ignores most of this anyway, it's just not as critical as on a normally asperated engine that has to struggle to breath in.

 

Larger motor= larger power increase. I would go with the L20B engine.

The throw on the crank is 43mm or a total stroke of 86mm. The stock rods (145.9mm) can be swapped for the longer 152.5mm rods from a Z20E motor and will require the Z20E pistons as well for their reduced pin height so they don't extend out of the block. Lot of work and like I said probably not needed for a s/c motor.

 

A blower (or turbo) is going to put a lot of pressure on the next weak link... the pistons. Here's a link for more info on stock and forged pistons and their applications:http://forum.ratsun.net/showthread.php?t=2159

[nismopu]

more SC stuff.

 

http://forums.hybridz.org/showthread.php?p=845423#post845423