wow...

these look like monster intakes....


I would have scraped the air filter box and ran the 3" duct and placed the air filters in front of the radiator

 

Double throttle plates per side.

 

yeah and 3" pipes for cool air from in front of the Radiator... K&N filters ect


what a kit.... black powder coated... Just cost money....

 

those are pretty, but some tests show little performance gain!

i much prefer these stainless steel with large volume plenums, and long tube runners, T/Bs on the front work out great with the plenums, has internal trumpets for runner inlets.

the 2 factory T/Bs are more tham large enough, its cylinder distribution, that messes up air flow.
no doubt expensive also!

 

Lister used a setup like this in their XJS

Ron's right, the factory TB's flow around 600cfm each more than enough for high HP.

I do not like the dual TB intakes. The TBs are not ideally placed and IMHO could lead to very uneven air distribution between the cylinders.

The pic Ron posted I think are ideal for the road car, but very expensive. I was talking to a guy here in Melbourne Aus who built 800hp NA V12's for Hydroplanes. His advice to me for lower cost road manifolds was:-

Cut the plenum off and weld on a 100x100mm box section about the same length as the stock plenum. Move the TB to the front and your good to go. Low cost and according to him a vast improvement in breathing over stock.

 

The great Roger Bywater at AJ6 engineering used to have a similar photo of this sort of inlet on his site, but I cannot find it there anymore. The site said is was hugely effective, (the figure of about +50 BHP sticks in the mind) and he used to offer them for sale, but said he stopped as they were too expensive.


I did email him a year of two ago to ask how much they would be if he were ever to offer them again, but sadly no response. The Warrjon idea of a bigger welded plenum sounds good, but how would one synchronise the forward-facing throttles each side?
Greg

 

I kind of Liked Marcos down draft set up in Rust 2 Rome, though I do not wish to mess up my bonnet

 

Turn the TB's on their side with the shaft facing up and connect them together with a rod.

 

Aj6 eng. Ram Plenum tuned length induction system kit for the V12 produced during 1986-92. This beefed up a standard engine by nearly 70 b.h.p. but was too expensive to manufacture. Close to 600 b.h.p. was possible from a race engine. We first started producing our large throttles for this application


no longer available... sad... every one likes 70 more HP....
maybe we can talk him out of the Drawings for this design...

 

Too right, Jonathan. Let's ask him how many orders he needs to get going!
Greg

 

Sign me up!

 

I really was hoping to get a reply on the run of the TWR manifolds... as to cost as they have recast the first one(s)



and how much he is willing to charge for a run if we can come up with a group of us... looking like 3 so far...?







what is every one thinking of the cost as they look very labor intensive ....

 

The problem with the TWR manifolds (according to Alan Scott) is they don't start to make power until nearly 5000rpm, great in a race application when spinning to 8000rpm but not to good in a street car.

 

the problem With the TWR manifolds is getting him to sell you one this late in the game...

 

I recently found out that they had a lot of adjusting with this intake manifold. There were unequal amounts of air flowing down each runner. So, they had to put baffles inside the plenum to balance out the air flow down each runner. The largest thing that helped out the v12 was lengthening the runners. The original manifold had runner lengths too short for the RPM's used for normal driving and for the stock cam. Also the runner lengths were not equal...

 

hey guy, thats basicly what is said at post #4.

long runners, as close to length that would fit under hood, large plenum volume, TB at front.

and factory did the best they could with money available!

and remember this is not a race car engine, it was designed for smooth power delivery, and economy! and a V12 will never ever be an MPG king.

 

Interesting to look as I get ready for errands and yard work. Good weather promised us.


As to throttle body synchronizing, racers don't care as long as all butterflies are wide open on pedal to the metal.


We multiple carb guys played with sync early on. Got some on really close, others, not so much.


If didn't stall at lower speeds and all butterflies were open at WOT, we were good to go.


Carl

 

Intakes are NOT an issue on a stock engine. Runners are 33mm ID. Lengths are unequal but this will just spread the rpm at which each runner is optimal, not ideal but on a stock engine probably OK.


Some misconceptions IMO of the HE heads
1) Pocketed exhaust valve limits power – I believe it’s the shrouded intake valve and the exhaust port bowl shape that limits power.
2) Intake manifold does limit power , but not in the runner diameter (for a road car). Runner length could be increased, plenum is way too small and the turn into the air box is too tight. Jaguar fixed this on XJ40's with the plastic 90° bend.
3) Increasing the TB size or adding dual TB’s totally useless as the stock TB flows over 500cfm which will support about 700hp and the engine has 2 TB’s.
4) 33mm ID runners are big enough to support power in a 5.3L to 6600rpm.




After performing major modifications on my 6.0L heads, I seriously doubt intake manifold modifications will provide any noticeable increase in power without head mods. At a minimum de-shrouding the intake valve which in a HE head is shrouded until about 50% lift.

The problem areas in the intake are
1) Severely shrouded intake valve HE head.

2) The joint between the manifold and head, to fix this the head and manifold need to be filled and then matched. DO NOT gasket match as this will form a bulb and cause loss of velocity. This joint needs to be 33mm.

3) The port at the valve guide is very restrictive. I have not calculated the cross sectional area but at a guess it would be 50% of the up stream port, this needs to be opened to about 31mm or more importantly 754mm², this will equal the valve curtain area (stock intake valve) at 60% lift.

4) Intake valve seat transition is very rough with lots of cutter marks – this needs to be blended

5) Exhaust bowl just after the valve has a flat shelf, this needs to be rounded to allow the gas to flow more smoothly, flat surfaces tend to cause turbulence, which is exactly what I saw in the exhaust port exit.

 

Warren
Can you please explain this a bit more? I am not sure what "the port at the valve guide" means:
3) The port at the valve guide is very restrictive. I have not calculated the cross sectional area but at a guess it would be 50% of the up stream port, this needs to be opened to about 31mm or more importantly 754mm², this will equal the valve curtain area (stock intake valve) at 60% lift.
Thanks
Greg

 

I am referring to the intake port from the valve to the manifold flange. An ideal intake port is a ventui, so it does need to narrow, this increases the velocity of the air, but it needs to be sized correctly for the valve train, too big and it will reduce the force of air into the cylinders at low to mid rpm, too small and it will reduce air at all rpm.

A duct will only flow as much air as the smallest cross section will pass, (ie the valve guide area) so making the intake manifold larger will have NO effect on how much air we can get into the cylinder.

The problem with the V12 is the port at the guide is a little too narrow at 29mm and has a great big valve guide blocking a portion of the passage (see photo). So we need to open this area out BUT NOT TOO MUCH. From calculations 31mm (754mm²) is a good port diameter for the narrow bit with stock valve train (ie valve diameter & lift also = valve curtain area).

I hope I have answered your question.