Most install a tunnelram on an engine to improve performance. This design had an evolution of engineering principles applied and was an improvement over the older designs. It is not unnecessarily huge in volume.
Nice work, it would be interesting to see the theory tested. What size carbs do you plan to use?
Supposedly bigger plenum is better with smaller carbs, big carbs small plenum. If it’s too big car will not launch hard or be lazy on gear changes. I have some articles from bill jenkins and they greatly reduced plenum volumes even though they were way over 8000, but the engines were small and short stroke. Lot of give and take I guess. Also length and what harmonic wave you’re aiming for makes a big difference. Play with this calculator for tuned rpm ranges
Awesome, thank you
On a big block I think your head port is about 6 and I bet the tunnel ram is 7.5-7.75? That 12.5 length gives a great 4th harmonic boost 5500-6200 but probably falls off a little early since you never get into the 3rd harmonic 7000-8000 boost.
Awesome, I was just asking that lol
Yeah it peaks 58-5900 but still carries pretty well out to 67-6800
Pretty close because based on those numbers if I’m right about the intake length peak would be 5850, cam would influence it too. But appears to be pretty close. You could always shorten the length by milling the base where the top bolts but then there’s no turning back unlike adding a spacer lol
After welding on it and fitting it to my decked heads I had removed about .200, I don't want to surface that thing again... pain in the butt lol
Head port length plus intake runner length equals the distance input?
Yes, exactly and from all the sources I’ve seen it’s pretty darn close. Most sheet metal intakes target the third. However low rpm stuff usually can’t get enough length for third so the fourth is used. Do you happen to know the length on a m1 tunnel ram? Also here is another tech source about taper etc
So that’s 7 for the long side of runner, what’s the short side measure? Need the average of both. For plenum area the basic rule I’ve seen is at least 50% of engine cubic inch size up to 100%. You can tape the bottom of the plenum up and fill it with water and convert ml to cubic inches. My try1 small top came out to 173 cubic inches for reference
I need to look into the math on the plenum before I start playing with the TR1 I have for my 340. Nice job. The cutoff disc obviously worked, but I think for jobs like this a slitting saw is the optimum tool to use. Good slitting saws get pretty expensive so I've been using various diameter (3"-7") carbide tipped trim saw blades. Even the cheap thin ones from HF are useful. You can buy cheap arbors but I just make them from scrap on the lathe. In aluminum they go like a hot knife through butter. Cut very well on steel too, but you need to pay attention to rpm and feed rate. Probably set the mill to minimum speed and plenty of lubricant to prevent smoking the teeth.
