1/16th diecast to model scale comparisons

[mrbob2]

Hi, I an old model builder getting back in to building. I'm building a 82' Chevy citation funny car for my best friend. I bought a Cruz Pedergon Discast to use as the base for my model. I need to back date items to the 80's. One off the biggest issues is the blower unit. I bought a Revell Hawaiian Funny car kit and found that the scales are not the same. 
It appears that the discast 1/16 is larger then the Revells 1/16. Why is this? Does anybody know where i can get a resin enderle style injector that is the same size as the diecast model. I was thinking of making my own mold for one but why ttry to re-invent the wheeel when i'm sure somebody has already come across this issue. 

 I guess my best solution is to buy a resin motor from Shapeways or one that I saw on Amazon.

Thanks for your help and i look forward to sharing my build with you guys as soon as i get it started.