Test and Tune Dissappointment

[Super73]

[QUOTE=prostreetC-10;4339841]Your carb is not just too big.......it's WAY too big and hurting you more than I think you know. A 355 spinning 6,500 with 100% VE, and you are no where near that, is coming in at about 658 cfm. QUOTE]


Are you sure he is not seeing more than 100% VE?? With the info provided and head data I got from summit, the motor actually sees 104.2% VE according to Engine Analyzer (With a few guesses on combo 11-1cr and 1 5/8 30" headers).


Also take in to consideration every intake has flow restrictions often requiring more CFM from the carb to help over come that issue. This goes for head restrictions too..

In a perfect world, I would agree that you don't need a bigger carb than the motor can pump, but the world is not perfect.




I happen to be on Summits web page for other things and I got a pop up askling if I needed assistance (First time I have seen that) So I asked about flow numbers for the 200cc 64 chamber head you are using. Only info I got was 261cfm/176cfm @ .600

If you give me ALL the details of your build, I will put it in Engine Analyzer and see what it says for your motor.. Most of it I figured out looking at the thread but I don't know:
Header tube diameter and length
Compression ratio
What center line the cam is installed at

I plugged what I could find in and guessed on a couple things. I guessed on headers (1 5/8 and 30" long) and compression ratio (11-1).. The TQ of the motor does not start going up drastically until 3,200-3,300. TQ peaks about 5,000rpm (437ftlbs) and HP around 6,200 (467hp). Actual CFM according to the program in the upper RPM's is 705@6,200 and 733@6,600..