math help for TB recremendation

LX XLR8R · 01-10-2003, 02:36 PM

i know how to figure out the CFM a motor needs but where do i get CFM ratings for TB's?

motor in question is a 408 with AFR 185's,custom cam,Spider intake(vicjr with elbow for TB and injector bungs welded in) ..those heads wont breathe much above 6200 with 408cu so figure that to be the max RPM..i am guessing in the neighborhood of a 75mm or 80mm..thanks in advanced..

BTW the dyno pull to achive the power that i build "my" combo after was used with a 750cfm demon

Dark_5.0 · 01-10-2003, 03:32 PM

Thats one awesome set-up. If it were me I would go with a 80mm TB due to the large displacement of the engine.

Later,

885.0L · 01-12-2003, 12:16 PM

I found this searching for the same answer.http://snow.prohosting.com/~johngift/intakefab.html .The formula is near the bottom of the page have to convert mm. to inches.hope this helps.

fiveohpatrol · 01-13-2003, 04:38 PM

the bottom of this page lists some flow data for mass air sensors and throttle bodies.
http://www.kellnet.com/chambers/intake_flow.htm

going by this data, and assuming that the diameter is in linear proportion to the flow rate, then here's what a couple other TB's would most likely flow
80mm: ~960CFM
85mm: ~1070CFM

is that of any help?

01-10-2003, 02:36 PM	#1
LX XLR8R Dirk Diggler Join Date: Feb 1999 Location: SLOATSBURG, NY Posts: 1,931	math help for TB recremendation i know how to figure out the CFM a motor needs but where do i get CFM ratings for TB's? motor in question is a 408 with AFR 185's,custom cam,Spider intake(vicjr with elbow for TB and injector bungs welded in) ..those heads wont breathe much above 6200 with 408cu so figure that to be the max RPM..i am guessing in the neighborhood of a 75mm or 80mm..thanks in advanced.. BTW the dyno pull to achive the power that i build "my" combo after was used with a 750cfm demon __________________ 95 undecided cubes, AFR 185s,undecided cam, undecided intake, and a 150 hit 89 "turbonotch" 2.3T You might want to hold on..i saw this on a cartoon once

01-10-2003, 03:32 PM	#2
Dark_5.0 Registered Member Join Date: Apr 2001 Location: Staging lane Posts: 4,337	Thats one awesome set-up. If it were me I would go with a 80mm TB due to the large displacement of the engine. Later, __________________ 92' LX-Big brakes, Lots and lots of suspension, GT40X heads, Ported cobra intake, stock cam, Vortech SC trim. 00' Lightning-Stock 88'CRX-13 second ego killer

01-12-2003, 12:16 PM	#3
885.0L Registered Member Join Date: Sep 2002 Location: Slave Lake A.B. Posts: 9	I found this searching for the same answer.http://snow.prohosting.com/~johngift/intakefab.html .The formula is near the bottom of the page have to convert mm. to inches.hope this helps. __________________ 88 5.0l atrim 8rib pulley stock bottom end ported heads & intake stock.T.B stock. c&l 76mm mass air conv.19lbs inj.vortech fmu 255lph intank. man. vlvbdy.c4.3000tci stall b&mpro rachet. 3.73gears tagirdle. ssm lowers all for $10500can including price of car.

01-13-2003, 04:38 PM	#4
fiveohpatrol I'd rather be basketweaving Join Date: Feb 2000 Location: Indianapolis Posts: 2,551	the bottom of this page lists some flow data for mass air sensors and throttle bodies. http://www.kellnet.com/chambers/intake_flow.htm going by this data, and assuming that the diameter is in linear proportion to the flow rate, then here's what a couple other TB's would most likely flow 80mm: ~960CFM 85mm: ~1070CFM is that of any help? __________________ NMRA O/C 9516 NA pumpgas stickshift 347 10.65@125.6, 6.73@100, 1.41 60ft Last edited by fiveohpatrol; 01-13-2003 at 04:44 PM..

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