Been working on this before my engine leaves to get done. Any advice or guidance? It’s still a prototype but I 3D printed one out for fitment. I tried to make the airflow smooth but it’s still just based off a SWAG. Thought it would be better than just a straight diagonal run from the block to the carb. 130mm in height with an 80mm offset towards center. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login View attachment 2839914 View attachment 3417972
What carbs are you planning on using? If 40DCNF (or even if not), locating them so the stock (or a stock-looking) carb airbox could be used might be a consideration. Won't you need some additional structural provision(s) for a linkage mechanism between the two banks?
I've looked at this problem a number of times. It's a pita. Deck lid clearance is problem 1. Runner length has to be reduced to fix that, but that only makes the runners 'kink' the air flow because of the port spacing, unlike the 2V. Linkages are workable, just fiddly. It's been done, so I know it's possible. Just never made any economic sense for production runs given the large number of custom bits etc.. for carbs. What I did was start with the base plate setup for all 4 carbs. Then you can run the 'tubes' to the cylinder head. Helps to build a mock up of the engine to work to. It's honestly less hassle to adapt the BMW ITB's to the head. Huge! Flow gains and injected. But that's just me. Good luck with the project!
I’m not too worried about fitting a stock air box because my car isn’t staying stock. I’m just doing this for a one off solution for my engine. Changing things in cad is easy right now. I think I’ll 3D scan the engine so I can mock it all up as you suggested in Cad.
Runner length will have the biggest effect on the power band with this type of conversion. Shorter for top end, longer for bottom. That said, after loads of Dyno testing and tuning getting the length correct is critical, Dyno Sims also bear this out. The play between cam timing/lift and air velocity, etc... Get it right and the engine sings, get it off and it falls on it's face where the length is all wrong. These engines love short runners for high rpm screaming. The fuel injection change helped with bottom end tq. As they increased runner length. If you're so inclined I highly recommend getting Dynomation 6, http://www.motionsoftware.com/index.html One off projects are fun... They can also get out of hand... Just ask mark.. mke
Hi Anthony, not sure if you've seen these. Made by Germany company Formula GT. There is some more detailed pictured and dyno sheet on their website. Cheers, BB Image Unavailable, Please Login
Nice work on the manifolds. I recently fitted individual filters from Pierce to my carb 308. The sound is identical to running without filters. I know this because I have been tuning the carbs and taking quick test drives without filters. If I lose a few hp by not using the stock air box (debatable) then so be it. The intake moan/growl is what a Ferrari should sound like.
I would suggest you shorten the manifolds in case you want to keep them under the deck or sell to anyone wanting to stay under the deck. You can always add longer trumpets to get the right harmonics. I would also use the IDF webers since they are cheaper and lots of Chinese copies out there plus lots of parts available. I printed a 2V version but have been too busy to get some cast. Image Unavailable, Please Login
Looks great! I was in such a rush to print I had a brain fart and got the height based off the existing manifold. I’ve since corrected it and will print one soon. The good news is at the orrery height it’s pretty much a straight shot so I can machine them on my cnc mill.
I'd be interested in a 2V pair if you can machine them. Casting will be a real pain unless they are cast tubes welded to machined plate flanges.
