It just keeps getting better (and more expensive)

[CDMBill]

As long as we're having fun, IR manifold (think traditional injector stacks) vs. dual four barrel TB on Tunnel Ram vs. front facing throttle body plenum on Tunnel ram base? All EFI.

[JeffMcKC]

I think you need a plenum on a N/A engine and air does not like to turn

[CDMBill]

I became curious as Kasse has an IR manifold for the Boss 429 stuff he is selling now which has cast in plenum under valley tray area connected by individually drilled passages into the port floors. And, Jay Brown's Injected cammer obviously works well.

My general survey of combinations and inquires with some of the aftermarket sheet metal manifold companies seems to confirm the idea that the two TB's on a more or less conventional tunnel ram is the best way to go. Makes for a tall hood though. Not that I would go that route or anything.

We'll see what turns up at DW.

[jaybnve]

I'm actually going away from the IR manifold because I think it is a bottleneck for my engine. Looking at the current sprint car small blocks, most of them use 3" throttle butterflies on each cylinder, and the butterflies on my old Hilborn setup (feeding 585 cubic inches) are only 2 7/16". A sheet metal intake with a plenum should, by all rights, be a lot better, and I'm looking forward to getting some dyno data on this over the summer.

My sheet metal EFI intake is built using two front mounted 90mm throttle bodies, for hood clearance reasons. I've been told that having the air turn corners is not as big of a deal as having air/fuel turn corners, and since the injectors are in the runners I'm hoping that I don't lose too much by not having the air come in from the top of the intake. But that would be another interesting experiment; it wouldn't be any big deal to make a new top plate for the manifold, for dyno purposes only, and mount some throttle bodies on top for comparison with the front mounted position. If I did that, do you guys think I could just mount the two 90mm throttle bodies on top, or would I need to go with two 4-hole throttle bodies to get the best results?

[JeffMcKC]

I think it would be fine to mount them on top like a set of Ron's Toilet Bowls. Jay the intakes dont run to dry at least on mine, I can say that at Idle, with a injector PW change, it takes over 6 seconds to see a AFR change happen. There is a lot of fuel to burn off and reversion going on.

I had a lot of guys telling me there was not any difference in throttle body placement two years ago and one is fine, now have changed their minds. Good luck with them, they are like a Carb Tunnel Ram put a lot of timing in them static.

[TheSilverBuick]

I just want to say this is very interesting reading. I have no where near the brain power to wrap my head around air flow dynamics, but facinated no less.

[JeffMcKC]

I just put two on top cause it looks Cool

[jaybnve]

They look cool on the front, too. I'm actually going to modify this setup to make the throttle bodies aim straight ahead though, because with the air entering at an angle as shown in the photo a bulge was required in the hood scoop. An UGLY bulge...

http://fepower.net/simplemachinesforum/index.php?topic=86.0

[CDMBill]

They do look cool indeed. I've been foolin' around with PipeMax and it looks like it all might just work with the available cast manifold. I run 19* at the bottom cell on the map rising to 25* in the surrounding cells and on form there up to 32. I hope the baseline is close, setting the mechanical idle with one pair of throttle blades was interesting. With two sets it''l be even more fun. I presume they'll be symmetrical in operation and therefore a single TPS will be fine. I think I'll leave one on the other TB as a back up.

What are air flow dynamics? I just thought bigger was better and two is better 'n one.

[milner351]

Amazing work as always Jay.

[brandontinley]

holy cow, what happened to the days of cramming a big holley and a bunch of nitrous on it till it breaks parts, then back it off a little, i miss the old days but enjoy all the new technology

[JeffMcKC]

LOL some of us are not Bottle Baby's

[brandontinley]

yea but for the money they sure are nice way to make alot of power

[JeffMcKC]

Its worse than Crack once you have had a taste

[CDMBill]

Maybe I'll switch to crack, its cheaper. This was another one of the lobes on the cam I pulled out when the roller lifter gave up. What you are seeing is a physical depression in the flank of the lobe as the cumulative pressure cycles of the roller on the lobe begins to push the lobe material to the side. This is opening flank of an intake lobe all of them have this new 'feature'.

With 2.30" stainless valves, 1.8:1 rockers and moderate spring rates the cam becomes a consumable part just like valve springs and lifters.