Ross Nicol
GT40s Supporter
I will admit to performing a stupid act. I took a 4BBL EFI / single plane Victor Junior induction system off my new 302 race motor and fitted the 8 stack injection system from my previous motor. Now why was that stupid? I hear you say, well here's my story.
I've always been under the impression that individual throttle bodies/ 8 stack injection was the ultimate in induction systems, probably because they replicate the sexy look of the IDA Webers but use modern technology with all the tuning advantages. Therefore it took me a quite a while to appreciate that I can get more HP from a 4BBL.
Now I'm a lateral thinker but my background is electronics not mechanical so I rely on this forum a lot for Ideas and information.It didn't surprise me then that in my thread titled "Max power & torque for a 302" I posted a week or so ago, that Jac Mac would respond with a one liner " Try a 4BBL Ross ". Now when Jac Mac speaks you should listen, but I got him to explain further by PM so I could prove to myself that it all makes sense.
I spent a few days with my books and on the website (GT40s.com) of course, and then it dawned on me I should load Dyno 2000 simulator onto my computer (purchased way back in 2002 and never used) to run some simulations.
Well how surprised do you think I was when I read the user manual and it described individual runner induction limitations.Absolutely backed up Jac Mac's theory (Ross' mental diary,never question that man again) and the simulations I ran proved I will have more top end power at the next race meeting.
Here's the theory in simple terms.A typical Weber 48IDA / or similar sized stack flows about 330 cfm per barrel.While the sum total of all 8 barrels is over 2600cfm, the important difference is that each cylinder can only draw from 1 330 cfm barrel.With a 4BBL on a single plane manifold each cylinder has access to 4 barrels, reducing restriction during peak flow and increasing high speed horsepower.
Adam C another respected technical man on this forum made this statement " I love the look of Webers especially on a GT, but they really don't make much sense to me ".
My next race meeting is at Sandown 12th and 13th of May after which I will be able to describe the results of returning to the 4BBL.
Ross
I've always been under the impression that individual throttle bodies/ 8 stack injection was the ultimate in induction systems, probably because they replicate the sexy look of the IDA Webers but use modern technology with all the tuning advantages. Therefore it took me a quite a while to appreciate that I can get more HP from a 4BBL.
Now I'm a lateral thinker but my background is electronics not mechanical so I rely on this forum a lot for Ideas and information.It didn't surprise me then that in my thread titled "Max power & torque for a 302" I posted a week or so ago, that Jac Mac would respond with a one liner " Try a 4BBL Ross ". Now when Jac Mac speaks you should listen, but I got him to explain further by PM so I could prove to myself that it all makes sense.
I spent a few days with my books and on the website (GT40s.com) of course, and then it dawned on me I should load Dyno 2000 simulator onto my computer (purchased way back in 2002 and never used) to run some simulations.
Well how surprised do you think I was when I read the user manual and it described individual runner induction limitations.Absolutely backed up Jac Mac's theory (Ross' mental diary,never question that man again) and the simulations I ran proved I will have more top end power at the next race meeting.
Here's the theory in simple terms.A typical Weber 48IDA / or similar sized stack flows about 330 cfm per barrel.While the sum total of all 8 barrels is over 2600cfm, the important difference is that each cylinder can only draw from 1 330 cfm barrel.With a 4BBL on a single plane manifold each cylinder has access to 4 barrels, reducing restriction during peak flow and increasing high speed horsepower.
Adam C another respected technical man on this forum made this statement " I love the look of Webers especially on a GT, but they really don't make much sense to me ".
My next race meeting is at Sandown 12th and 13th of May after which I will be able to describe the results of returning to the 4BBL.
Ross