Sc14/12 Supercharger On A 4k

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I'm looking to putting a charger on to a 4k. i don't have a new 4k to do this too yet but when i do get one i plane on balancing the engine, shaving the head and finding a pear of extractors. just the average re-make. i have the webber for it.

 

so whats the extra power average? :hmm:

[tenyearguarantee]

a rough calc is to take the power it has now, then multiply it by 1+(boost [in psi]/14.7psi) 14.7 is how many psi in a bar of pressure, you need to get a ratio of the boost added to the engine relative to normal pressure the engine is exposed to, ie standard atmospheric pressure = 1bar

 

ie say you want to run 7.4psi at your engine and your 4k puts out 60bhp then the new power is 1+(7.4/14.7)*60 = 90bhp

 

 

obviously due to losses etc you'd the boost at the engine will be less than the sc is putting out

Edited April 22, 2008 by tenyearguarantee

[zilli]

how easy would such a conversion be?

[dfunkt]

hehe, the words "conversion" and "easy" never appear together.

 

there's all sorts of things that need to be done. water lines, oil lines, mounts, pulleys, belts...

[tenyearguarantee]

the sc14/12 are roots so the throttle needs to be moved to before the blower

 

blowing through a carb requires some thought as they wont have been made for extra pressure you'll need a custom plenum etc. Mounting is a small issue, selecting your pulley diameter for your crank to ensure the s/c runs well for your desired rev range and makes power when you want it and belts require a small amount of thought, not alot.

 

if you have the appropriate carb and plenum then the hard work has been done

[[email protected]]

the estimate that you say sounds ok :hmm: but why do all these lines have to be re-positioned. it all sounds a little to complex for the power output.

on the other hand if the engine was N/A, all balanced with a compresion ratio of 10.5:1 this should begine to keep up with a charged 4k. it would rev a lot higher 8000+,+ the cost of the work.

i don't think there is a simple way round this.

 

turbo is bolt on but can cost. i hear all the time people using a standard 3k head. 3k use flat top pistons with dished heads, 4k do both flat top and dished pistons. so what happens if you use a 4k flat top piston set up with a 3k standard head, does it work or should it just be shaved 40-60thou. corect me if I'm wrong i don't have all my ke knowledge with.

[tenyearguarantee]

the estimate that you say sounds ok :hmm: but why do all these lines have to be re-positioned. it all sounds a little to complex for the power output.

on the other hand if the engine was N/A, all balanced with a compresion ratio of 10.5:1 this should begine to keep up with a charged 4k. it would rev a lot higher 8000+,+ the cost of the work.

i don't think there is a simple way round this.

 

turbo is bolt on but can cost. i hear all the time people using a standard 3k head. 3k use flat top pistons with dished heads, 4k do both flat top and dished pistons. so what happens if you use a 4k flat top piston set up with a 3k standard head, does it work or should it just be shaved 40-60thou. corect me if I'm wrong i don't have all my ke knowledge with.

 

 

superchargers are not very thermally efficient, the newest roots max out at around 75%, most older roots brand new max at 65%, second hand who knows, 50%?

they give nice low down torque which is why people use them, i don't think you'd get so much of that if you ran n/a, you'd have to increase the stroke or something. They have a nice sound too which is pretty cool.

 

You could try a centrifugal s/c, they are small like a turbo, look like a turbo, almost as efficient as a turbo and don't require the throttle to be moved like a turbo. they only really shine at higher revs tho like a turbo, so you may as well go turbo...

[Felix]

From the research I have done an SC14 is can flow enough air for for power levels of up to 230hp. On a k series motor you would probably never get that far though.

 

You need to lower the compression ratio of a motor to be able to run high boost levels, to avoid running into detonation issues. Probably the easiest way would be with a thick copper head gasket, or opening up the combustion chambers.

 

A draw-thru setup with the carb in front of the blower would be the easiest system to setup. Though you wouldn't be able to run an intercooler which would limit absolute power. Supercharged motors respond well to headwork and a cam like in NA mode. 8 psi on a worked motor is going to make a hell of a lot more power than 8 psi on a stock motor.

 

The best I have seen was an SC14 on a highly developed mini 1275 motor (think opened up to 1380), running in drawthru mode with a 2 inch SU carb. The mini ran a 12.8 sec quarter on slicks.

Edited April 22, 2008 by Felix

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if your saying it can't get more than 90bhp+ out of a 4k N/A your about to be corected. my friend has a race ke30 3k an all that has is balanced pistons, not crank or piston rods and a lumpy cam with half an outlet system, no extractors and stock carby.

 

so nothing speciall just a lumpy cam and balanced pistons and the head was done a little but all up under $800 for 100kw+ atw on there dyno. the power to wait says it all for me. and yes the motos is reliable just don't hold 7900RPM for 8 laps.

 

to reach 90BHP is realy not that hard to do if you know how to N/A a motor properly but it will set you back a little more but boy does it go hard. if done well the power can be felt right through the rev range till just befor it valve bounces than :hmm:.

 

every little bit helps.

4K EFI systen.

32/36 carb.

extractors.

shaved head and block deck.

1.5-2''system.

balance all high RPM parts

grind cam.

don't have to port polish but it is good.

lighten flywheel.

ect. whats listed are the main power makers. i would think that would keep up with a charged 4k.

[oh what a nissan feeling!]

:hmm: :y: :y: 100+ kw@wheels out of a 1200, no forced induction, stock carby! :( :o :D

 

Mate, lay off the booze. :no2:

[[email protected]]

in not twisting what i said but i ment bhp not kw and a cam that lumpy can do it.

[Redwarf]

85hp ATW, 120hp at the fly. 1360cc 3K rally motor.

 

All dyno'ing done in 4th 1:1 as it should be. If they're doing runs in 3rd, figures may not be right.

 

I've been playing with 3/4K's for many years, and if you can do 90 hp ATW without DCOE's, a BIG peaky cam and some serious head work, I'd be very suprised.

 

I'll bring the popcorn on dyno day.

[[email protected]]

il make the call.

[Redwarf]

My choice of dyno? ie: one that's been calibrated since it was installed?

[tenyearguarantee]

From the research I have done an SC14 is can flow enough air for for power levels of up to 230hp. On a k series motor you would probably never get that far though.

 

You need to lower the compression ratio of a motor to be able to run high boost levels, to avoid running into detonation issues. Probably the easiest way would be with a thick copper head gasket, or opening up the combustion chambers.

 

A draw-thru setup with the carb in front of the blower would be the easiest system to setup. Though you wouldn't be able to run an intercooler which would limit absolute power. Supercharged motors respond well to headwork and a cam like in NA mode. 8 psi on a worked motor is going to make a hell of a lot more power than 8 psi on a stock motor.

 

The best I have seen was an SC14 on a highly developed mini 1275 motor (think opened up to 1380), running in drawthru mode with a 2 inch SU carb. The mini ran a 12.8 sec quarter on slicks.

 

when you got 230 was that just based on airflow calcs or was it on some engine that you played around with heaps? could i get some details on what is required for that sorted of output?