308 V12 conversion begins

I took a good fresh look at the suzuki TBs. 46mm throttle plate, 42mm exit (so suzuki is using exactly the same size port I am proportionately). The throttle plate can go up to at least 48mm, probably 49mm. The exit ID can go to 46mm leaving 1mm walls.

Right now I’m like 50mm wide x 43ish tall. I’ll have to play with the port and have another good hard look at how the TBs would/could sit with the heads on the block and see what can be done. I'll post some pictures when I start messing with this....it will be very tight if it works at all.

The other thing that occurred to me is that now that I’m talking about 24 injectors with fairly short duty cycles the stock Suzuki injectors are probably pretty close to the right size. …and I have them.

 

A 360 is 2.115" x 1.070" making the equivalent diameter 41mm. At about 50hp/cyl vs 45 for the suzuki ferrari is doing a touch better velocity wise. With my planned 65hp/cyl and a 46mm port vs the 360 at 50 hp/cyl with a 41mm port, I am 3% smaller proportionally.

I'll have to through it on the flow bench and see what it does.

The suzuki TB will bore to 48 at the plate and 44 exit unless I weld a bit, the I might get another couple mm.
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Here's some quick pictures of just how tight it is.

It looks to me like if I cut the lower and inner mounting ears off the TBs and weld them into pairs and set the height so the narrow section of the injectors fits around the cam cover mounting flange and maybe notch the flange a touch the Tbs will drop right in. I’ve got 4 extras so I may cut 2 up and see how it looks.

I’m also thinking I’m going to take what’s left of a stock plenum I have kicking around and stretch it to V12 length and use it as the air box. Then if I finish the cam covers with a satin polish it will look just like a stock engine….you know, move along folks, nothing to see here
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Here's what I'm thinking with the TBs.

The good news is they fit, the bad news is I lost 20cfm. The TB itself flow more than I can measure on my flow bench without re-calibrating at a lower pressure so the problem has to be my clay work.
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Thanks Ernie, I'll try.

 

They seem like aluminum. I just took the piece of ear I cut of tand hit it with the welder and it seems it build up fine so I think I'm OK.

I'm not exactly sure how to attach everything. I don't have room for the stock suzuki rubber things. I'm thinking maybe I'll make a bolt-on manifold and then drop the TBs in to holes with o-rings but I'm still not sure how to hold the TBs down in the hole.....maybe a forked clamp or I could weld something on.

Last, 140 cfm is only 10 less than 150, not 20. I do math better in the morning I guess. I think I see where the problem is and it looks easy to correct and get back up where I was. It looks like I haved a choke point just up from where the 2 runners become 1 port.
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we're trying to teach him about sharing.

 

i took a few minutes to play with the flow lose I'm seeing.

The clayed in port with the little maniflof flows verey nearly as well as the open port did. The problem comes when I add a TB, any TB. The suszuki TBs are 46mm I also tried a 50, 52, and 60mm and found that the 3 big ones all flow the same and about 2cfm better than the 46 which I already knew was a touch to small.

A 6" velocity stack flows about 2 cfm better than any on the TBs...so the problem is that the porting I did with the port 20 degrees lower is not right with the new air direction.....and goes to show why you always flow heads and intakes as a set. I'm stil looking at 750 hp of air, but I think with some work I'll be able to correct the problem.

Now back to the EFI job I'm supposed to be doing.

 

They have a pretty big OD. I'd have to raise the TBs at least an inch to get the space to fit them.....then the TB needs to be bigger. maybe though, I can try it on the flow bench with the TBs raised and see what happens.

 

I spent another hour onth eport and it's starting to come around. It's now flowing 145 which is a touch more with the 46mm TB than it was before with the staight stack and about what it was flowing with the short stack before i started all this.

There were a couple issues. The main one was I need a slight curve to get the TB to sit at a the right angle and I didn't have the TB tangent to the curve, there was angle. 15 cfm to go.

I'm also playing a bit with raising the TBs enough to use them with the lower ears and use the stock rubber mount. It's a work in progress.

 

Someone was nice enough to send me a few pictures of a ducati 996 intake manifold....which look almost exactly like what I've layed out in clay. I must be on the right track here.
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Ok...I might have to change my plans for the TBs.

I was just offered 54mm ducati TBs and they are things of beauty....just look at the oblong exit to help hold the port shape longer up the runner and the shower injectors.....mmmmmm.

The guy is going to send them to me to test on the flow bench and is pretty confident he can hook me up with 10 more if they work out. I need to go weld in the port so I'm ready to go when they get here....like hanging stockings on christmas eve
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I cleaned up the port tonight so I should be able to weld it up tomorrow night.

It's hard to do justice to the hole I made with a picture, but it's about 1" x 2". I do need to weld up the bottom a bit...ok more than a bit, like 3/8"-1/2".....I am a glutton for punishment.

The ducati guy is sending both 50mm and 54mm TBs for me to flow test. The 54s have the shower injector only so I would need to add the lower injectors and the 50s have the lower injectors so I would need to add the shower injectors. I guess the right answer will depend on what size I finish the port up at and exactly how far away the TB ends up getting mounted. It's good to have options.
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OK, it needs some more grinding but the hole is gone, the floor is raised some and there is what will be a flange for the manifold. The port look much bigger then it is looking straight at the head because of the angle between the port and the flange. I think it's about right but I may need a little more welding on the floor of the port, we'll see what the flow bench and the calipers have to say tomorrow.
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