| Author |
Message |
'75 308 GT4 (Peter)
Advanced Member
Username: Peter
Post Number: 2940
Registered: 12-2000
| | Posted on Monday, July 21, 2003 - 1:05 am: | |
For a future project on a sub two-litre four-cylinder engine with modifications (cams, hi-comp pistons, etc), but without going to the expense of installing DCOE type throttle bodies (I can fab'up a steel, or even an aluminum plenum-type manifold for way less).
If I was injecting a 308 motor, it'd be a carb one like my GT4 and I'd go with individual intake runner throttle bodies (both TWM & Jenvey make DCNF replacement bodies... But big $$$).
Thanks for the cfm/hp figure. |
Mark Eberhardt (Me_k)
Member
Username: Me_k
Post Number: 625
Registered: 5-2002
| | Posted on Sunday, July 20, 2003 - 4:09 pm: | |
Most of the time, the throttle body maker tells you what it will flow. You need about 1.2 cfm/hp. Higher performance engines tend to like bigger throttle bodies (less restriction). There is very little harm done by using a bigger throttle body than you truly need. Unfortunately it comes down to best guess and trial and error. What is it going on? On a stock 308 engine, I would start with 65-70mm, if it has cams and such, I�d probably go 75-80mm. Sorry it�s not better info. |
'75 308 GT4 (Peter)
Advanced Member
Username: Peter
Post Number: 2937
Registered: 12-2000
| | Posted on Sunday, July 20, 2003 - 2:11 pm: | |
No one here has any info? I should've been more specific when I posted this, that its for fuel injection, not carbs.
I found this so far. Both these sites have some good info:
http://www.firebirdgt.com/formulas.html#Throttle_Body_Sizes
http://snow.prohosting.com/~johngift/intakefab.html
Any others? |
'75 308 GT4 (Peter)
Advanced Member
Username: Peter
Post Number: 2933
Registered: 12-2000
| | Posted on Saturday, July 19, 2003 - 6:32 pm: | |
Can anyone here supply some sort-of general rule, or formulas for calculating the necessary size required for single throttle body applications (single feeding many cylinders)? I thought I remembered seeing it in an aftermarket engine-management site, but I'm turning up alot of dead-ends (lots of info for multiple/individual-intake-runner throttle bodies)
Thanks! |