Let's design MFI intake and throttle body diamters for my hotrod engine...(jluetjen?)

dtw · 07-13-2003, 07:41 PM

This weekend I picked up a pile of MFI parts, which caused me to realize that my hotrod engine is probably not going to be happy with the ~33mm "T" stacks it started life with. I measured the intake ports this weekend, noting that they are every bit of 40mm. Included in the lot I picked up this weekend is a set of magnesium '70-71 "S" stacks. They are in great shape and look to be around ~36 mm wide at the top. They included throttle bodies which are completely frozen (but I'm working on that).

What's y'all's input on intake and throttle body size for my hotrod 2.4L motor? I can use the mag stacks and bore them out if necessary. I've also got 2.4T and E plastic stacks lying around, if one of them happens to be a bolt-up solution. To refresh everyone on the proposed motor specs:

JE 10.5:1 pistons, GE60 cams, 40mm intake ports (doh, forgot to measure exhaust), SSI, twin pipe sport muffler.

Paul Thomas · 07-13-2003, 09:02 PM

Dave,
That is a big intake port for that size motor. The RS was only 36mm and the SC was 39. I would start by getting your hands on some 73 S/RS plastic stacks and measure the bore before they curve outward to form the molded velocity stack. Compare that to the 36mm intake port and try to achieve the same taper %. Does that make sense?

Also, i would deffinately call or email Matt at Eurometrix. I know that is my answer to everything but he is a good source of info. Your gonna have to get him to rebuild the throttle bodies anyway, might as well break the ice. Email Bruce Anderson too. He has all of the formulas for carb selection, maybe you can apply that to MFI intakes.

Paul