Boost levels?

[333pg333]

ORIGINAL: Indi9xx

ORIGINAL: 333pg333
Jon, there are some very good cams already available out of the US and not too expensive especially with your pound. They're ground from fresh billet and you could get them made to your specs I'm pretty sure.

Off the shelf ones are not suitable for the 3.2 and the ones for the 2.5 are a bit of a compromise (one size fits all spec's type mentality)

My 2.5 cam spec has taken some work to formulate and I don't want to hand all that work over to what will effectively be a competitor. The 3.2 cam is another item with a different delevlopment path.. All will become clear a little later this year.

Also not happy about the quality of the ones I have seen from the USA.

Jon, These are not off the shelf items or reground welded stock ones. These are made from custom billet blanks to your specs. Made by the same person that supplied John Milledge so they're of very good quality. Anyway it sounds as if you've progressed far enough yourself. I just thought I'd point it out if it may be of any help for you.

 

[TTM]

ORIGINAL: Indi9xx
Interestingly... I also have some options opening up for an intake manifold especially suited to the 3.0 and 3.2 turbo hybrid engines with a specific feature I have not seen in any other performance 944 turbo intake manifolds.

Care to elaborate on this?
I'm overchannel and my english is rubbish (even more so on the phone), so please reply.
I have a carbon fiber intake pipe that could do with some modification and as of now I'm not too sure what to make of it...

 

[333pg333]

+1 on the elaboration of these intakes.

 

[nick_968]

+1

 

[homesea]

ORIGINAL: Indi9xx
Interestingly... I also have some options opening up for an intake manifold especially suited to the 3.0 and 3.2 turbo hybrid engines with a specific feature I have not seen in any other performance 944 turbo intake manifolds.

Is it one of those electric 'superchargers' off ebay? [][]

Serious, would 2.5 manifolds be in the pipeline?

 

[zcacogp]

ORIGINAL: Indi9xx

First 3.2 to go for wasted spark programable ignition gets free fitting and dyno setup!

First 3.2 to go for a camshaft, gets free fitting and free dyno setup!

[]

Does it have to be forced induction? []

>WondersHowToFindAnother200ccInMyS2<[]


Oli.

 

[Indi9xx]

ORIGINAL: TTM
Care to elaborate on this?
I'm overchannel and my english is rubbish (even more so on the phone), so please reply.
I have a carbon fiber intake pipe that could do with some modification and as of now I'm not too sure what to make of it...

Well, its not top secret and as soon as its finished it will be blatently obvious anyway..

Application 3.0 and 3.2 944/968 turbo engines using the 8 valve head.

All the aftermarket performance manifolds seem to be a bit of a bodge based on a 2.5 turbo as the application.

The standard 944 turbo has round ports for the intake. The 3.0 and 3.2 turbo engines use a head with oval or letterbox ports.

All the aftermarket intakes for the turbo application, because they are designed with the 2.5 market in mind, are (in some cases if your lucky) have round cross section intake port runners with the last section ground out to make them blend into an oval port. I have seen some 3.0 engine conversions where the intake runners are not even modified to blend into a oval port, even though the part has been ordered for a oval port head!

The reason Porsche designed the head with this shape port has one massive advantage in port flow. Which is you get a closer port velocity on the roof of the port compared with the floor of the port. The greater the difference in port velocity between the roof and the floor, the more turbulant the airflow becomes.

There is good and bad turbulance for every engine design. Two flow characteristics are swirl and tumble.

Typically an 8 valve engine benefits from whats known as swirl. This is where the airflow causes the air to swirl around the cylinder like a vortex during induction and ignition strokes. This can be designed into a head/intake manifold or modified into it.

Typically a 16 valve engine benefits from the tumble form of induction airflow, where the air is encoraged to enter the cylinder in a pattern where it effectively rolls (horizontal swirl)

In an ideal world swirl is a better form for any engine, but with 16 valves in a conventional 16 valve layout, its almost impossible to get, without an element of tumble.

In an intake manifold, and to an extent the intake port, you want to control the air for good flow and velocity, avoiding if you can any tumble or swirl. You really want to try to create the swirl or tumble as it enters the cylinder. Normally performed via attention to the control of airflow in the last section of the intake port. This gives you maximum airflow without interferance to flow and velocity.

With a circular cross section intake manifold or port, as the port curves you end up with the roof of the part (long side turn) a different length than the floor of the port (short side turn). This causes a difference in air speed between long and short side turns, causing turbulant airflow, eddies and a whole host of unwanted airflow characteristics.

With blending a circular cross section into a oval or letterbox cross section, you end up with another problem of the air speeds, paths and characteristics, already messed up by turbulance, which cause even more chaos. However, this can be reduced by having the radius into a transition angle change of less than 12 degrees.. Rarely seen on the better manifolds modified or supplied as for the letterbox port heads being used.. and still a compromise though.

So, the obvious solution would be a manifold designed with an oval cross section to match the shape of the intake port. This has the benefit keeping the short and long side turn lengths as close as possible (still a big difference, but every bit helps) while still maintaining cross section area. This has an effect of increasing the airflow of the part while also reducing the initiation of tumble (it still happens, just much reduced) while also increasing port velocity.

Until recently, there has been some problems in being able to offer something with oval or letterbox fabrication. However due to some new contacts in the manufacturing and motorsport industries the required tooling and materials are now available and being put to work.

So, one of the unique (to 3.0 and 3.2 turbo heads) features is the use of oval runners.

 

[333pg333]

ORIGINAL: nick_968

+1

I assume it's some sort of version with variable runners. Wonder who's developing it? Sounds interesting.

 

[nick_968]

The intake ports on a 2.7 head are the wrong shape for optimum flow on a turbo engine and if you design your intake manifold around this shape you wont be making any performance improvements over the standard one that is ground out to match the oval port shape. The head is a bigger restriction than the standard intake anyway. There are other things to change before the intake.

 

[Indi9xx]

ORIGINAL: nick_968
The intake ports on a 2.7 head are the wrong shape for optimum flow on a turbo engine

It depends on if you want optimum torque or optimum bhp from the head. For torque its not a bad design for an 8 valve, for BHP use can then sacrafice some of that torque when specifying cam profiles and the turbo.

The port shape promotes good gas velocity, which then results in being able to specify a cam with more overlap without ending up with a bad idle or low rpm road manners.

A lot of head modification experts tend to concentrate on head flow figures at the expense of port velocity or the dynamics of flow in the same way that many tuners concentrate on bhp at the expense of good torque.

ORIGINAL: nick_968
if you design your intake manifold around this shape you wont be making any performance improvements over the standard one that is ground out to match the oval port shape.

I dissagree and time will tell. The main thing is not just the amount of air the intake will flow, but how its presented to the head which I am targeting.

ORIGINAL: nick_968
The head is a bigger restriction than the standard intake anyway. There are other things to change before the intake.

Well, as per my earlier post, camshaft and intake are something I am looking at right now. (intake includes throttle body)

Other parts of interest include the crossover and exhaust manifold design, not to mention the intercooler which we are also looking at a next level for to compliment our level 1 and 2 items.

The 3.2's also benefit from the ability to go larger on intake and exhaust valves than even the 3.0 engines can take due to a 4mm larger bore size without valve shrouding becomming a problem. So there is that option also.

We have done a lot of development recently stretching the standard intake manifold to the limits, almost on purpose to see how far it can go. Part of the reason for flogging the standard intake manifold to death on the dyno over the last 2 years has been to prove these other tuners wrong. We have found that the standard intake manifold is not too much of a problem bellow 400 - 420 bhp. (thats on 2.5, 2.8, 3.0 and 3.2 engines)

Above 400 bhp the standard intake manifold becomes a restriction not just in flow, but also how the air is actually presented to the intake port and a throttle body upgrade alone does not cure this.

The cam is often also overlooked on 944 turbo type engines, hybrid or not, which is why we are also working on this aspect as we feel there are benefits to be had for even more mild levels of tune of 2.5l engines and upwards.

Last year saw a lot of development on exhausts, in particular the turbo exhaust discharge pipe. From all the work we have done so far, we are pretty sure of our results and that we are beginning to map the limitations of each part through real world on the car testing.

 

[nick_968]

Agreed the intake runner flow must be equal and this is the main problem with the standard intake. The camshaft development has been done to death by other tuners namely Jon Milledge, there is a cam for virtually every option, engine size and turbo size. The turbo downpipe has been done and is proven to be a restriction at high hp levels if left standard. If someone can produce a dyno proven and flow balanced intake and TB (70 - 76mm) I am definately watching with interest, there is already one available that does this but it is quite expensive and not available in the UK. The intercooler is an interesting one. I developed my own one in the end and it works well on the road but it remains to be seen how well it works in conjuction with the water cooling on the track. For a track car you need to be very careful when you move away from the 951 setup of having seperate dedicated airflows for the IC and the rad. Also agreed its not just about flow or peak hp.

 

[TTM]

ORIGINAL: Indi9xx
Well, its not top secret and as soon as its finished it will be blatently obvious anyway.

When is it suposed to be finished?

 

[Indi9xx]

later this year, its still at an early stage right now.

 

[sawood12]

I wonder why we don't see vane type features on the back of intake valves to introduce swirl into the induction airflow right upon entry into the combustion chamber. I realise it would be very tricky to manufacture, but perfectly possible with modern CNC grinding machines.

What about consideration due to the length of the runner? In reality the airflow through intake runners is pulsing longitudinally with areas of low and high pressure. The 997 GT2 manifold was designed to exploit this effect. Is this something that is too difficult to design for in aftermarket products? Would it deliver much improvement?

 

[944Turbo]

ORIGINAL: Indi9xx

I can't comment.. I might break the rules.. can't say about the 55lbs injectors we do either, or the wastegates.. or all the new stuff we do.. []

I can tell you that we recently got just shy of 500 pounds of torque at around 3500 rpm on a 944 turbo at what appears to be the countries lowest reading DynoDynamics rolling road a few days ago! []

Well Done all!

small side note though, unless it was in shootout mode it probably wasnt reading as low as on the dyno day - either way its going to be a mighty quick car,

Tony

 

[333pg333]

As a side note and someone who will have to deal with some extra hp soon enough, I wonder how much power not only the drivetrain components can take, but what about traction? I currently have a pretty stock 2.5L engine with S2 crown wheel and pinion that shortens the final drive ratio by about 15%, Vitesse stage 5 kit, and a larger front mount i/c. I run 1.3 to 1.5 bar with E85 and would guess it equates to about 350bhp. It also has KW 2 way race suspension + metal bushings, Tarett adj sways , Motorsport LSD and use 255/285 18" R888.
In other words you'd be thinking I have plenty of grip. However I am on the cusp of traction issues at certain parts of the tracks we run on. One in particular is pretty run down and needs a resurface so that is understandable but the issue is how much is too much? Of course there are different ways of dealing with the tune and powerband but I am still very concerned about more hp that could even render the car slower around the track due to not being able to put the power down. I am hoping to install some form of traction control through the incoming LINK ecu. The difficulty will be in tuning this in a manner that will not inhibit the general feeling of the car.
I wonder what some other guys are doing that have some of these big hp / torque motors?

 

[Indi9xx]

ORIGINAL: sawood12

I wonder why we don't see vane type features on the back of intake valves to introduce swirl into the induction airflow right upon entry into the combustion chamber.  I realise it would be very tricky to manufacture, but perfectly possible with modern CNC grinding machines.

What about consideration due to the length of the runner?  In reality the airflow through intake runners is pulsing longitudinally with areas of low and high pressure.  The 997 GT2 manifold was designed to exploit this effect.  Is this something that is too difficult to design for in aftermarket products?  Would it deliver much improvement?

With valves modification to the profile over the years has been a hot subject. In particular there are modifications which can be used to allow you to use a cam with more overlap while controlling flow direction and reducing low rpm backflow during the cycle. As for valve mods to improve swirl, its one of those things that it would be interesting to experiment with.

Intake runner length and pulse length tuning is really interesting and quite easy to calculate. In an ideal world you would get real gains from having each runner of a tuned length set to give a benefit of a specific rpm range to match the cam timing. Unfortunately this often means having a tuned length with is unpractical to fit in the engine bay, or you trade of to time the arrival of the pulse to coincide with another cylinder, which then sees less of a reflected wave, this subject has been the topic of entire sae papers and you could easily write a book on the subject. The boxer type engines can exploit this effect with a greater degree of benefit as you can tune the intake manifold length so that the pressure wave caused by a cylinder on one bank will benefit a cylinder on the other bank directly with the ports on the plenham actually facing one another. Porsche have been playing with switched intake manifold runner lengths on the 928 S4 since 1987 and the 993 varioram since 1996, way before the 996 or 997

 

[Indi9xx]

ORIGINAL: 333pg333

As a side note and someone who will have to deal with some extra hp soon enough, I wonder how much power not only the drivetrain components can take, but what about traction? I currently have a pretty stock 2.5L engine with S2 crown wheel and pinion that shortens the final drive ratio by about 15%, Vitesse stage 5 kit, and a larger front mount i/c. I run 1.3 to 1.5 bar with E85 and would guess it equates to about 350bhp. It also has KW 2 way race suspension + metal bushings, Tarett adj sways , Motorsport LSD and use 255/285 18" R888.
In other words you'd be thinking I have plenty of grip. However I am on the cusp of traction issues at certain parts of the tracks we run on. One in particular is pretty run down and needs a resurface so that is understandable but the issue is how much is too much? Of course there are different ways of dealing with the tune and powerband but I am still very concerned about more hp that could even render the car slower around the track due to not being able to put the power down. I am hoping to install some form of traction control through the incoming LINK ecu. The difficulty will be in tuning this in a manner that will not inhibit the general feeling of the car.
I wonder what some other guys are doing that have some of these big hp / torque motors?

One of the problems and benefits of the 3.2 engines is they have enough torque that traction becomes a real problem, not just at low speeds in low gears, but also at high speeds (I have experienced it at 120 mph without being an animal with the controls)

The benefit is that if you find yourself with way too much torque, you are winning a battle in the tuning game because its very easy to trade some of that torque low down in the rpm where it can cause traction issues for BHP at higher rpms where it may not translate into a traction issue.

Traction control and a solution for the 944 turbo is something thats been nagging away in the back of my mind for about 3 years ago.. just about the same time as I found myself loosing traction at 120 mph as it happens! I have a few cunning ideas, but nothing has come of them yet and may never come to anything

Having said that, I think that the limited tyre width that will fit on a 944 turbo rear, as well as limiting traction, is also what saves the transmission from damage that I think would occur with the big torque motors if traction was improved, as wheelspin almost acts as a safety fuse.

 

[pauly]

ORIGINAL: Indi9xx

With valves modification to the profile over the years has been a hot subject. In particular there are modifications which can be used to allow you to use a cam with more overlap while controlling flow direction and reducing low rpm backflow during the cycle. As for valve mods to improve swirl, its one of those things that it would be interesting to experiment with.

Are these the valves that were around 20+ years ago with a groove machined into the face of the inlet valve to limit back flow during overlap and a step on the back of the exhaust valve that supposedly reduced exhaust backflow ?.

 

[Diver944]

ORIGINAL: Indi9xx

about the same time as I found myself loosing traction at 120 mph as it happens!

No wonder my rear tyres are always bald after a service []

Just kidding - they are always fine