TRD SC on 3VZ-FE issue

[Paul Woods]

hi chaps,since december ive now built two 3vz-fe's with TRD SC's on,and it was johnny who noticed his SC was making 3psi on the 4psi pulley....just for info this SC is designed for the 1mz-fe and makes 4psi on that engine with the 4psi pulley,naturally!

Now i put the 3psi reading on johnnys down to 2 things...

1)he was reading a bar gauge while doing mach 2 and eating a big mac while taking a narrow gap one handed while chatting up birds walking past and shouting "smoke me a kipper luv i'll be back in 10 minutes"

2)could've just been an oddity with johnnys car

but now that jinjas is completed he is using a psi gauge and it too reads 3psi from the 4psi pulley,both 1mz and 3vz share the same crank pulley size so its not that....so does anyone have a clue why the 3vz should see 1psi less on the same charger? is it down to volume of air consumed by the engine,in other words a 3vz with ported heads (both engines had head work) is lowering the pressure produced by the charger? feasible?

it matters not in the long run as we can simply fit a 6psi pulley and get 5psi,fit a 7 psi pulley and get 5.5psi and etc...

discuss...

[Marksman]

Paul we've seen silly things like this on the 4agze. If for example you overdrive the SC too far and everything heatsoaks the air temp increases and thus the pressure with it. You're tempted to think higher boost gauge reading is a good thing when in fact the opposite is true!

Maybe as you've got the POCVIP thing sussed maybe you could invent an air molecule counter to fit to our inlet manifolds, as this is the information we really need, as pressure is only half the story...

Cheers,

Owen.

[GaryA]

Not compression ratio ? Only thing i can think that is different :hmm:

[GaryA]

Are the Cams the same as the 1mz ?

[Goldy]

This could be down to the improved portwork i feel.

Youre using the same size pulleys at i presume the same engine speed and load and air temp humidity etc (when measuring the psi produced), the pressure being measured thusly at the supercharger outlet (is there a port for it? ).
The only thing i can think of is if the engine is now more efficient than it previously was, itll have less intake /exhaust tract restriction which will effectively drop the pressure although volume of gas throughput will be higher, which is a good thing.
If youre measuring say 5 psi on an identically equipped engine, run at exactly the same speeds and conditions as the current supercharged 3vz's and theryre showing lower pressures it (to my warped thinking) indicates more efficient evacuation of gasses throughout the entire induction/exhaust system.
Remember higher pressures indicate restriction. Put your hand over the exhaust pipe and what do you feel? Pressure but less flow (volume) will take place.
That pressure then gets reflected to the intake through the overlap period and lowers the volumetric efficiency of the engine.

Anyways, thats my take on it, im sure Steven Hawking will be along soon to demonstrate why im wrong with his thermodynamic tabulations..... :mrgreen:

Sounds pretty much spot on that tony.

Roots blowers don't have any internal compression, they just put a volume of air through the engine per revolution. If its only reaching 3psi it means you're engine is more volumetricly efficient (or something like that). My supercharger book says its not all about Psi's to get high bhp.

Be careful how fast you spin the charger with larger pullies.... the temprature rise chart for the m45 is here :

http://www.goldy.biz/M45deltaT.gif

[wayne]

dont get comfused with boost and flow paul
boost(psi) is a measure of the restricion of the engine
flow is a measure of how much air atually passes though the engine

tri this for a experiment :d
weld a 1" tube on the end of teh exhaust....now see if you get back your missing boost :D

lol
and yeah
its all about v.e

[Paul Woods]

excellent discussion fellas,pretty much what i was thinking but wasnt 100% sure...so the 1psi difference is purely due to these two engines having had headwork.I know phil gets 4 psi on his 4 psi pulley on the 1mz but that has a different CR,cams are bound to be different etc.

Right what i need to do next is bolt a TRD SC onto a stock 3vz and see if it produces 3 or 4 psi,if its 4psi we know the headwork is doing good things!

[msherry21]

Well, I'll be down in a week or 2 Paul with both on trailer....hopefully, and If I can find something to Tow it with!:jump:

Michael.

[biteme]

Hmm. I did say this, and you said I was wrong! :) In fairness I also suggested the CR was to blame and probably Tony Blair as well ...

Never mind though *blows a fucking big raspberry to Durham* :)

You'll have a TRD unit soon enough to try on a std v6 :)

[Paul Woods]

yeah like i ever listen to you mate lol ,it could be a combination of compression ratio and headwork,or as others have said a general overall better efficiency of the 3vz...time will tell.

[biteme]

I guess. Be interesting to see how the Waspberry Whipple works out!?

[Goldy]

I guess. Be interesting to see how the Waspberry Whipple works out!?

Twin screw chargers compress the air so you should be getting your 27,000psi no matter what.... BOOOM lol

[biteme]

Woohoo.. So I won;t know if it's the S/C or the semtex under my seat!