GTRACER88

Lately I have been receiving PM's about turbos and I have decided to make a thread addressing some of these questions.

Turbos are not great because the have turbo lag.
Lets start with the infamous turbo lag: Take a stock 2v and add a single turbo kit with a T70 Master power turbo with a A/R of .96 and you will see FULL BOOST at 3500 rpms. The "turbo lag" is from idle to 3500. However, this is a good turbo to work with, if one is looking to go above 550 RWHP. The T70 can produce 700 RWHP. If one desires to stay below 450 RWHP, a single T61 or T57 would be a better choice. The spool will be quicker and will utilize more of the power band.
A properly sized turbo for a stock application will virtually have zero lag. Take a T61 with an A/R of .58 and you will have full boost before 2500 rpms. If you down shift, your going to be above 2500 rpms, you will be in full boost and there will be instant power. In road racing no one is really ever below that.

BTW look up Y2k02 or something like that. He has a twin turbo mustang making crazy power. Show me a supercharger making the same power as him on the same boost...

Are ball bearing turbos worth it?
Ball bearing turbos are not worth it IMO. They cost significantly more to only spool 200-300 rpms faster than non ball bearing turbos.

Single or twins?
Eye of the beholder. IMO single. Twins you are paying for the extra turbo, waste gate, extra piping, etc... They both will perform the same when properly sized.

Is getting a right sized turbo for a car is very difficult?
No. This is a long read so bear with me. For starters we must figure out the CFM that our engine will flow. For that we must use the formula (CID X RPMS) / 3456 = CFM
(281 X 5500) / 3456 = 447.2 CFM at 100% VE. Since this doesn't exist we must live with what we have which in reality is 85%. Take 447.2 CFM X .85 = 380.12.

Next we must look at the pressure ratio. This formula is (# of boost + 14.7 which is atsmosperic pressure AKA 1 bar) / 14.7 = PR

In your case you might look at 8 psi.
(8 PSI + 14.7) / 14.7 = 1.544

Lets also say the density ratio is 1.33. Just take my word on this... its a long formula and I don't want to write it all out and explain it.

Now we want to find the airflow in Lbs/min. We now use this formula...
Outlet CFM X Density Ratio = Actual Inlet CFM
380.2 X 1.33 = 505.666 CFM
Take that and multiply it by .069 to get the conversion for CFM to Lbs./min
505.666 X .069 = 34.89 Lbs/min

This is a compressor map of a much better turbo but you can use it as reference. http://www.turbomustangs.com/turbotech/compmaps/t61.jpg

The X axis will be the 34.89 Lbs/min while the Y axis will be the 1.544 AKA Pressure ratio.

Looking at that map, the coordinates falls right in the "ring or Island" of efficiency. Each ring represents efficiency with the best being 78%. Notice the coordinates falls right in the 78% range. You want to be in the 70% or above.

Hope this helps!

For those that want to get more acquainted with turbos I highly suggest your read this:
http://www.turbomustangs.com/turbotech/main.htm

GTRACER88

Im not going to compare turbos vs superchargers.. The argument is old, out played, and people will always have differences of opinions. Everyone may know my stance and ill leave it there.

Bman2000

and turbos are better. lol

Aereon

We all know twin turbo's aren't necessary in most applications, but from a turbo fan boy's perspective twin turbo's are just so fuggin sexy.

I've poked around turbomustangs, just depressing most of the time reading about how almost everyone can get this except for us in nazifornia=/

cliffyk

Solid information--well done!

Mr Graystang

the only edge that S/C's have on turbo's is cost. Great info ! Sticky ???

GTRACER88

Hehe. I dont disagree

They are incredible attractive. But to me any turbo system is attractive. Either single or twin.

Thank you sir. Took my time writing this out. Hope this helps others with their turbo needs.

GTRACER88

Fixed!
Kenne bell costs $6000 or so. My entire single turbo kit will cost me $4k and this is entirely custom. Pony down performance is the turbo kit I would go with and they cost $2500.

K member is a must change period if your staying N/A, Turbos, or Supercharger. It really does change the feel and I recommend it to everyone. My car feels more agile.

H0SS302

Good info, I was always under the impression that twin turbos were effective when you want a rocket ship. you have 1 big snail and a smaller one to compensate for the lag on the big turbo.

Dteal23

good good info