One of the interesting things with the caddy engine is what we have in intake manifolds ... the most common being the edelbrock ..... before that we had modified stock intakes or converted 460 intakes ... then there is bulldog and boogieman and the 1475 intake ...beyond that you have hand made intakes ..... the crazy part is almost all of them are built without any testing leaving it up to the user to make them work or just deal with the problems
I have run stock ..modified stock ..edelbrock...and a sheetmetal tunnel ram .... I have flow tested every intake I can get my hands on .... and I have collected up a bunch of 460 intakes because I thought at one point there had to be a better running intake
Some like potters seemed like a good idea when first talked about. ...a intake that you could swap tops on to work with different carbs. ... but then when it was made it has short runners and a huge plenum
Others like the bulldog have the same problem ...the runners are longer but to much plenum ..to much runner cc .... everyone thinks more is better ...I think this intake has been updated since this one
This one shows promise on the bench but has the problem of being an adapted 460 with port match problems
This one is hand made and kinda looks like something that could run good ... I got it off eBay and need to convert it to square flange to try it
Dual quad intake that I picked up from a member on here(thanks again jwsunup).. In process of converting it to run dual 454 tbi units run by megasquirt ecm.
This is a reboot of the other thread to talk about intakes how they work and along with what's been made
Scott in your opinion what is better? Smaller plenum and longer runner, if so why? I think the velocity in the longer runner might help a milder engine. Maybe force a few more cfm's in during the BDC. As the piston is now coming up. Just my thoughts. Curious what you think.
Longer runners are better ..... if you look at most modern fuel injection engines when fuel drop out was no longer a worry they went to very long runners ... now with the caddy most of the time we run carbs so we have to worry about fuel and signal response to the carb... larger plenum size will dampen the signal so a smaller plenum will respond faster .... most of the time when you add a spacer to increase the plenum and it helps one of two things is happening ...either the carb is too small or the air speed through the carb is high enough that it can't make the turn into the runner
If we are to talk airspeed and runner length you are kinda right .... peak HP will happen at 320 ft per second and peak torque at 250 fps .... now all engines are ram tuned ... I am not talking about the wave tuning with long runners like in the early sixties ... what I am taking about is that air has mass it takes time to start it moving and time to make it stop moving ... as the runner gets longer you are right in that it gains speed but the variable is not more cfm but a lower rpm at which you reach 320 fps
^^ Good posts. You should be able to estimate things by playing with the intake manifold calculators at the Wallace Racing website.
If you look at potter's sheet metal intake you can where the idea for the cast intake came from .... when I saw this intake I questioned him on the extreme taper of the runners ..... and how the car drove with this intake .. now Richard was always a Max output guy so it was hard to get a straight answer about part throttle.... the taper when I got a answer happened more because it was easier to build that way and looked cool ... and though it drove I got the impression that it was not a easy drive ...
The intake he proposed to make looked like a good idea .. you could change the top ..straight runners and a plenum as wide a carb base
What we got of course was this intake... large plenum short runner .... I had prepaid for 2 ..so was not real happy ... when I saw it I told Richard it looked like a good intake for a roots blower
That Is the manifold that I mounted the 8V-71 blower on. I am hoping that even the short runners will help. The data logger is recording 29lbs (abs) with the 6-71 blower at the far end. Manifold pressure isn't helping if the charge isn't getting into the cylinders, it just heats up the air that just makes the problem worse.
