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347 WITH A mp70

2K views 17 replies 9 participants last post by  Speedy911 
#1 ·
is a mp70 with a 96 housing big enough for a built 347, ..looking for low 10;s hig 9;s
 
#6 · (Edited)
uggggg ............

Lets do the math then, and see how it comes out on a T-70
compressor map, instead of ...... "well it should cause they run it on 302's and 289/4.6L's "
Thats great but he has a 347 ....... not a mild 302 or 4.6L mod-motor


347 X .5 X .8 X 6,000 / 1728 = apx 500 cfm N/A

11 + 14.7 / 14.7 = 1.75 PR

500 X 1.75 = apx 900cfm at 10 psi

900 X .076 = apx 69 lbs/min

Now lets plot 70 lbs/min and 1.8 PR on compressor map of a T-70


As you can see at 10-11psi and the flow rate needed for a 347 at 6,000 rpm
the T-70 is way off its efficiency compressor map.
This will put alot of extra heat into the system and give issues.

The last line on a compressor map is known as "The Choke Line"
You want to avoid going past it at all cost if possible

Definition:
Choke line: The maximum centrifugal compressor volume flow rate is normally limited by the cross-section at the compressor inlet. When the flow at the wheel inlet reaches sonic velocity, no further flow rate increase is possible. The choke line can be recognised by the steeply descending speed lines at the right on the compressor map.

You guys need to watch the bad info you hand out, "just because
someone else did it on a totally different motor". They make those compressor maps FOR A REASON !!!


Here's some good reading on how to properly pick a turbo
http://www.enginelogics.com/cmaps.html
 
#11 ·
i don't want to have to crank the boost to the moon..around 14 psi is good.the more i read about it and learn .the more i lean toward the t-76..i don't want to buy a t70 and it not do what i want it to do then turn around and spend 1200.00 on a t-76..from what i see a t-76 will get it there with room to spare with out pushing it to the max
 
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