DeanF

iTrader: (1)

I am just gathering bits together to fit an FMIC to my Uk 94 which has a TD05 Turbo.
Current Mods (engine side)

Walbro Fuel Pump (optimax & Octane booster always)
Full Decat
Blitz Induction
Gruppe-s headers & uppipe
Prodrive Ecu
Manual Boost Controller 17 ish Psi
Samco Hoses Etc
Last R & R John Nobles 311 Bhp & 272 Ft/Lb

Pipe work is going to be Home made as such I can go to 3" Max (Pipe bender won't handle bigger)
Would 2 " be better for spool Up ?? Or for the loss of spool up time 3" would be more beneficial... Comments appreciated ,Thanks

Dean

DeanF

iTrader: (1)

Thought about using the flutted Hose off my Hoover, SHould hold 1.2 Bar of boost

David_Wallis

I used circa 62mm with my Diy FMIC..

DeanF

iTrader: (1)

Cheers david

Fredysan

DeanF:

I'm very interested in this topic too. I did some research about this, trying to find some valuable information. If you read the book "Maximum boost" from Corky Bell, there is a chapter about intercooling.

Mr. Bell say something about the drag losses in a pipe and this increase "too much" over 0.4 mach. If you make some calculations for a 2 litre engine with 20 psi taking in account this information, you'll see it's possible have a 2.25" pipe diameter without restrictions (If my memory is good, aprox 2.17" is the minimum). Why this? As the pipe diameters decreases, the air speed increase and you must try to keep the less volume to fill in order to have less lag.

I don't remember the exact numbers and formulas, but I'll post later when I have the book in my hands

Regards from Chile

DeanF

iTrader: (1)

Fredysan,

That makes sense, I did not just want to bend & fit the pipe work regardless, Wanted to get the Flow & spool up as optimal as possible,
Thanks for the Info & i'll look forward to the rest

Dean

Fredysan

Now I have the information...

Mr Bell say the maximum airflow speed shouldn't be over 0.4 mach or 450 ft/min because over this "magic" number the looses increases a lot. At the other side, the diameter of the pipes should be the keep at the minimum possible to have the less volume to fill, hence less lag.

So:

Speed = Airflow/ area

Let's assume our airflow at 20 psi in our 2.0 lts engine is 587 cfm with 100% of VE (The maximum possible).

Now

450 ft/seg > 587 ft´3/min / pi X (d/2)´2

Regarding Pi's and constants.. we have:

Speed = 587 X 3.055 / d(inch)´2
Speed= 587 X 3.055 / 2.5´2 = 283 ft/sec

Let's try with a 2.25 diameter pipe

Speed = 587 X 3.055 / 2.25´2 = 354 ft/sec

But, What about the volume to fill:

V1= pipe lenght X Area = Plengt X Pi X (2.5/2)´2
V2= pipe lenght X Area = Plengt X Pi X (2.25/2)´2

so V1/V2 = 1.5625/1.2656 = 1.23

23% more volume to fill

Now the interesting thing is see How long it will take fill this volume:

Time = V/ flow rate

If some one do this math, could be interesting... I got tired now...

Regards from Chile

DeanF

iTrader: (1)

Thanks Fredysan,

I'll put my Einstein head on & get my electronic brain from the draw & try to work it out.


Dean