Pro comp bbc intake min CSA vs 454r min CSA and minimum to maximum differences
 

Bought a pro-comp intake set up for efi with rails, 170$ off ebay, did this to test on a upcoming dyno project, even AFTER reading they have core shift, dont line up, mediocre, etc. On initial inspection and trial fitting to engione to check angles/ overlay gaskets on to check port opening alignment I was quite surprised it lined up real well. fit real well, no core shift I could see, they actually claim there molds are better than the ones that have been used by edelbrock and other company's for years. Delved further into it when I started port matching it and checking minimum CSA and found that #2 and #7 ports were 10% smaller than the rest (1/2 way in at bend), if ports were a true rectangle for discussion lets just call it square inches, so my tight ports were about 3.45ish, my average ports were 3.7 to 3.85, I worked on #2 and #7 until they were in that 3.7- 3.750 range.
Fast forward, in discussion with a couple other guys that do this the question comes up, was it a ****ty casting, was the 454r that I assume this is a copy of a flawed so the copy is also flawed or was this done on purpose for some reason? Last night Gimmefuel brought over his used edelbrock 454r, has had slight port matching done but nothing done to check or adjust the minimum CSA/square inches, any guess on how they compared? Is having a pinch point halfway thru intake runner thats 10% small in 2 runners a big deal? Going to find out on the dyno fairly soon!

Good info Smitty !

This is going to be an interesting test for sure.Can't wait to see the results. Would be interesting to get another box stock chineseium intake and compare modified to as cast back to back.

So back to this as I have time to finish typing this out, on examination the edelbrock 454r has Minimum CSA in biggest runner of 4.34 sq inches and smallest is 3.40 square inches, only 27.5 % DIFFERENCE best to worst and the average ones which still varied more than the Chinesium intake were around 3.80 but we had some at 3.68, one at 4.2 besides the other big one, some around 3.75 to 3.8, NOT IMPRESSED. If you ground on the edelbrock enough to even them up it would be HUGE, I dont think youd want to hand grind a port 27% bigger anyways. How important is a difference from cylinder to cylinder, I thought 10% was bad but I guess I could accept that now as ok, 27 isnt in the ballpark. Will the 454r outpower the chinesium, with its two "extra big" ports, I doubt it, well see, if anything the afr's will be farther apart cylinder to cylinder, unless, this was done on purpose (I highly doubt)

Your last sentence caught my attention. "Purpose". Who knows why they do what they do when what we think would be right would be so easy for them to mold without being exact as American. Or at the the very least make some sense as to why!!! They certainly get those little rice grinders moving in fast and furious but it always seems vin diesel and his crew have to go over to get the American muscle to compete. Just a guess vins using American muscle parts.

Btw you ever ck darts? They surprised me originally however there is some method to the madness. I've yet to see a bolt on intake make any power.

:cartman:
This carb spacer will get'r done :)


https://www.youtube.com/watch?v=9EwN8HjoYgE

Again Smitty biggest gains are up top = Inlet to runners...and those tight corners (usually inner 4 runners) need to be made more gradual...keep it nice and gradual. Finish with 80 or so grit..... :)

Most of your airflow is up top of runner and usually the farthest wall.

You don't compare port to port. You have to look at the whole port all the way to the valve. Port length needs to be considered as well. Size the port on the intake side to work with the head. Also, if you have a rectangle port you don't count the corners when calculating CSA. Air doesn't flow in the corners.

I think the edelbrock that is so far apart from best to worse is sand cast in socal or mexico

Good info, I'm curious to see the results. I'm doing a similar combo 540 with a Holley dominator efi. What's your expected peak hp rpm?