4k Superchargeing

[camerondownunder88]

Toyota range of blowers are positive displacement

[kickn5k]

Yeah it is a positive dispalcement. I wrote it wrong. I meant i have my setup to work out, aswell as a centrifical setup on a v8 that if this calculation works with would help heaps. I`ll have to get the paxton specs of capa. But if there prices on brackets etc are anything to go by the specs will cost me $100+. Quoted $895 for the bracket for 355 holden, bunch of jokers!!

 

stu.

Edited November 6, 2008 by kickn5k

[DearmanKE]

ah yeah, i hope those calcs are for positive displacement ones

[kickn5k]

ah yeah, i hope those calcs are for positive displacement ones

 

I was not too sure on it for a positive displacement S/C as it(calculations) asks for a max rpm. Seeing as boost only climbs maybe 0.5-1psi from 2,000-6,000+ with my setup. In saying that though, once i work out how pulley ratio effects size etc. i`ll work it out backwards. The calculations are very handy in working out how hard the engine can be reved with the blower on, but as my sc/12 only cost me $50 I'm not too scared to torch it in the quest for more boost and power.

 

stu.

[DearmanKE]

i havnt checked but I'm prety sure if you did 2 calculations at say 5000 rpm and 3000 rpm useing those calcs then you would get the same or similar answer, because the sc rpm to engine ratio will be the same stil...

darn it I'm gunna do it, il post my calculations here once ive done it in notepad lol

Edited November 7, 2008 by DearmanKE

[DearmanKE]

First set of calculation. 7psi boost @ 5000EngineRPM on a 1300 motor(4k)

 

 

1.3 X 5000rpm = 6500 litres/minute...divided by 2 to get actual amount... 6500/2 = 3250 litres/min

engines air req at 0psi boost

 

 

14.7psi atmospheric pressure + 7psi desired boost = 21.7psi

boost ratio = 21.7/14.7= 1.476

 

 

actual air requirements for 7psi boost at 5000rpm = 3250litr/min X 1.476 = 4797 litr/min

 

 

rpm needed by sc12(1.2 litre swept volume) for 7 psi boost at 5000rpm

4797/1.2 litres = 3997.5 rpm

 

 

pulley size ratio =

3997.5/5000rpm = 0.799

 

So circumference of crank pulley would have to be 79% of the circumference of the SC pulley

 

 

 

Second set of Calculations. 7psi boost @ 3000EngineRPM on a 1300 motor(4k)

 

1.3 X 3000rpm = 3900 litres/minute divided by 2 for actual amount... 3900/2 = 1950 litres/min

engines air req at 0 psi boost

 

 

14.7psi atmospheric pressure + 7psi desired boost = 21.7psi

boost ratio = 21.7/14.7= 1.476

 

 

actual air requirements for 7psi boost at 3000rpm = 1950litr/min X 1.476 = 2878.2 litr/min

 

rpm needed by sc12(1.2 litre swept volume) for 7 psi boost at 3000rpm

2878.2/1.2 litres = 2398.5 rpm

 

pulley size ratio =

2398.5/3000rpm = 0.799

 

So circumference of crank pulley would have to be 79% of the circumference of the SC pulley

 

 

 

TA DAH! :)

 

same result from different engine rpm

 

and just so people know i don't say darn my last post was edited automatically lol :)

Edited November 7, 2008 by DearmanKE

[DearmanKE]

Question:

 

With a Suck Through setup

 

what sort of fuel pump setup should i be looking at, obviously its not as necassary to have fuel pressure rise to keep above boost levels,

but should i still use a riseing rate regulator so that the engine gets more fuel when it needs it?

 

what other sorts of fuel setups could be used for suck through?

[Taz_Rx]

Suck/draw through only reqires a conventional carby fuel setup as none of the fuel system in under pressure.

Provided the pump you are using can still supply the AMOUNT of fuel you need at full power. :bash:

 

Something like a holley red, or carter green would be plently on a K motor.

Also use a good regulator, which obviously doesn't have to be a rising rate.

[kryton brown]

Those calcs won't work with one of those centrifcal type chargers as they don't move a set amount of air per revolution.

They operate like a turbo (although driven by the crank) and require the compressor wheel to be spinning at warp factor 9 before it will actually pressurise the air going through it..

[DearmanKE]

Something like a holley red, or carter green would be plently on a K motor.

Also use a good regulator, which obviously doesn't have to be a rising rate.

 

say if i got a carter green, what fuel pressure reg would you recomend?

[Taz_Rx]

Basically any reg that you'd use for an NA carby car.

 

Somethinglike this would be fine.....

http://cgi.ebay.com.au/HOLLEY-12-803-FUEL-...A1%7C240%3A1318

[Falken_KE30]

Keeping with the SC theme...

 

Why do they put the TB before the charger on a EFI setup? guess same with carby too..

 

I'm not 100% why

[DearmanKE]

mainly with carby, because if you have one TB controlling the air after the SC, (being the butterfly in the carby),

and your at like 4000 RPM, then you let off the throttle to change gears or to come into a corner or whatever, the SC is still going to be boosting, and where is all that pressureised air going to go if the butterfly is shut,

 

it can be done with a BOV or ABV, i was going to do this but have decided to go suck through,

 

however i have just discovered the seals in my SC need replaceing

 

which has f@$ked me right off as apparently you can't get the bearings out without destroying them and you can't get new bearings, and to replace the seals you need to take the bearings out... WTF!

[SLO-030]

CBC bearings to the rescue, those guys have most bearings know to man.

[Falken_KE30]

i pick up mine tomorrow.. got a permit to drive unregistered car too.. will let ya know. first supercharged car ive ever driven!!