Twin Intake for Twin Turbo

[LondonBenji]

5L, 800(ish)bhp and 620kg's? Oh holy crap.....

 

[striker]

indeed HOLY crap, and availeble in seven different colours down your pants, I presume,

I know of no kitcar with those values and they have build some crazy stuff over the years.

grtz Thomas

 

[Thermactor]

indeed HOLY crap, and availeble in seven different colours down your pants, I presume,

I know of no kitcar with those values and they have build some crazy stuff over the years.

grtz Thomas

The Can-Am Porsches of that era had the Toyota 7 beaten by an incredible margin:

"The 917/30 was the most powerful sports car racer ever built and raced. The 5.4 litre 12 cylinder twin-turbocharged engine could produce 1500 bhp with twin turbochargers run up to full boost, a simply astonishing 39 p.s.i, though it usually raced with around 1100bhp to preserve the engine. The 917/30 dominated in the CanAm series during the 1973 season. The 917/30 could go from 0-60 mph in 1.9 seconds, 0-100 in 3.9 seconds and 0-200 in 10.9 seconds and on to a top speed of 245 mph+. These staggering levels of performance, the attendant fuel thirst of the engines, and ever increasing risk, has led to the 917/30 sometimes being cited as the car that killed CanAm racing."

 

[striker]

turbo era F1 cars are even crazier than that. megatrons ran 1400hp from 1.5L 4 cylinders.

+ it's not the power only that interests me it's the weight vs power.

I know how 640kg's an 350hp cosworth turbo power feels like, I can only imagine what double + a bit would do.
grtz Thomas

 

[Thermactor]

Good point, I remember the heyday of turbo F1, truly nuts

 

[striker]

indeed crazy, still the canam cars are quite a bit havier than 620kg and the F1's of that age are also over that weight not by much, but what I wonder about is how the hell do you put 800hp on the ground with a "8krpm 5 liter turbo torque curve" on a car that only weighs 620kg, the tyres must have been ground to bare steel liners in about 2 launches methinks or maybe complete 1 lap, not that they exactly cared back then but still,

anyway back to topic about twin intakes,

Q1: what would be the + in running ITB's and turbo's instead of turbo's on plenum chambers?

a true twin entry without balance pipes has to my knowledge (which could be wrong offcourse) never been used in a race car exept the audi R 10 diesel car, which I looked at quite good at le-mans last year but couldn't find a balance pipe between the chambers note that diesels don't have air throttles. AER tried in the past on gas engines but reverted back to balance pipes after testing proved not competitive vs balanced, I dont know why though.

Q2: so what is the point in actullly doing that set-up?

or are you only triyng to improve equal flow in all cylinders using a tappered plenum form? in that case look at test done with laminova IC's the equal out almost everything if they can be mounted close enough to the head ports.

seems also that the vvt heads are better because of the steeper angle of the ports.

grtz Thomas

 

[Boosted2.0]

Q1: what would be the + in running ITB's and turbo's instead of turbo's on plenum chambers?

a true twin entry without balance pipes has to my knowledge (which could be wrong offcourse) never been used in a race car exept the audi R 10 diesel car, which I looked at quite good at le-mans last year but couldn't find a balance pipe between the chambers note that diesels don't have air throttles. AER tried in the past on gas engines but reverted back to balance pipes after testing proved not competitive vs balanced, I dont know why though.

Q2: so what is the point in actullly doing that set-up?

or are you only triyng to improve equal flow in all cylinders using a tappered plenum form? in that case look at test done with laminova IC's the equal out almost everything if they can be mounted close enough to the head ports.

seems also that the vvt heads are better because of the steeper angle of the ports.

grtz Thomas

1 - ITBs are purely a throttle response and modulation thing. You still run a plenum with them - the plenum is just before the throttle valve and not after.

The reason no-body runs a twin intake withotu the ballancing is if you have one turbo that starts failing or a bank that runs a bit lean or whatever you can wind up with very unbalanced conditions on the two banks which actually hurts power instead of helping it

2 - the reason for the setup is improved flow. A tapered plenum with a TB on the end and nicely engineered bells flows at damn close to zero loss.

 

[TOBES]

As stated above I have one of these manifolds for my RB30DETT.

The taper on this manifold is there to allow clearance for the brake booster rather than for flow reasons. In fact the taper may well adversely affect the balance between the ports as they have a known imbalance problem. No 6 flows approx 2% more than the first 4 and no 5 approx 1.5% more.(Tested on a flow bench).
Not a huge imbalance but, suspiciously, when fuel systems are pushed to the limits it is often these two cylinders that die first (may also be more heat at the back of the block??). The common fix is to flow test your injectors and install the highest flowing injector in no 6 and the next highest in no 5.
Tuned sensibly there is no problem and they flow significantly better at higher revs, especially when using the 3l block as opposed to the standard 2.5l.

A non tapered manifold may well provide more even flow...

 

[LondonBenji]

I'm pretty certain tapering is the way to go, have a look at the intakes for the Mclaren F1 engine and Ferrari's, generally all tapered.

But yeah, it needs to be calculated and from the sounds of it, it is wrong on that manifold but again from the sounds of it, it wasn't tapered for reasons of performance so it might not be possible to get the clearance and performance.

 

[Boosted2.0]

a 4" D shape extrusion with an 84mm TB on the end, no taper in the plenum and a properly tapered inlet for each runner in it can flow at close to zero loss to all cylinders on a flowbench - this much I know for a fact. Its not as pretty, but you can get the parts to custom make one for pretty much any motor from ross machine racing.

 

[Boosted2.0]

Also look at all the other manifolds posted - that Greddy is the only one with that convoluted shape.

 

[LondonBenji]

Have you got any physical examples of that, I'm having difficulty picturing it :S

 

[Boosted2.0]

Here ya go:

http://www.rossmachineracing.com/20vVWintake.html

 

[Boosted2.0]

Skyline:

Notice that none of these tapered inlets have such an aggressive taper on the end of the plenum and none of them make the air do that little jog after the throttle body like that Greddy does.

 

[Boosted2.0]

Some potential twin intake designs for the UZ motor:

Short Runner (high RPM torque peak)

Long Runner (low RPM torque peak)

 

[Turbo4L]

Dave you have seen the pics i sent you right? the ones that you put up under the forced induction project as thats what your talking about right?

I'm running twin plenum twin TB.
Just finished the TB cable and the link between the TB's.

 

[LondonBenji]

Thats an aggressive taper at the end of the plenum :|