Do any of you guys have direct experience comparing the 289 Shelby original intake with the Blue Thunder reproduction intake. I called Cobra Automotive and several others to find out about these intakes. Cobra Auto. said the new one would be worth about 7 HP. Some others said it wouldn't be anything significant and still others said it was worth alot, not specifying what alot was. Has anyone run these on the dyno back to back.??? Also, any knowlegde about extrude honing this intake?? My 347 made 388 HP with 289 heads(ported) and original Shelby intake (not ported) using cast iron HI-PO manifolds on the dyno (uncorrected for weather). Also used the 715 orig. carb. From the outside, motor looks EXACTLY like the original, except for headers. Thanks for anything you can shed on this topic.
I'd say you were very fortunate to get 388 hp from any version of stock heads and cast exhaust manifolds.. I wouldn't touch anything ....you are doing really well as is.. I wouldn't even change the oil jimbo
I would go with Curt's numbers if you looking for HP gains...I know he spends alot of time on the Dyno.....
Your setup and numbers are basically identical to my 347 but IIRC my engine builder used headers when he dyno'd the engine so yes, I'd say your setup is perforrming very well.
