[Fox944]

ITB's would require stand alone management. Realistically speaking....someone is looking at spending 5K for an ITB system to see a 10-15HP gain.

Partial Post: Please Login or Register to read the full post.

[flash]

i'm still waiting to see if they can actually make the gains on this engine - the question remains as to whether or not ITBs can make more power than dual resonance - we already get 10-15 from our manifold - to get another 10-15 above that means that the ITBs would be making 20-30 total, and that is a lot

Partial Post: Please Login or Register to read the full post.

[Fox944]

<!--quoteo(post=77254:date=Aug 10 2009, 09:52 AM:name=flash)-->QUOTE (flash @ Aug 10 2009, 09:52 AM) <{POST_SNAPBACK}><!--quotec-->i'm still waiting to see if they can actually make the gains on this engine - the question remains as to whether or not ITBs can make more power than dual resonance - we already get 10-15 from our manifold - to get another 10-15 above that means that the ITBs would be making 20-30 total, and that is a lot<!--QuoteEnd--><!--QuoteEEnd-->


i am fully confident that a properly tuned ITB system will yield gains of 10hp on our cars. 20-30HP is not unheard of from properly built & tuned ITB systems. The bigger issue is coughing up the money to have a 1 off unit built by a pro such has Lance Haywood, tuning the system and incorporating stand alone management. All that will cost big bucks and the gains would be minimal.

For most people, it just isnt worth it.

Partial Post: Please Login or Register to read the full post.

[flash]

yeah - i wonder how much of that 10 will be from the management though - 10 just isn't much of a gain for most people - now if the torque was seriously improved in a wider band, that might make the difference

we'll see how it goes - like you said, not an inexpensive proposition, with unpredictable results

Partial Post: Please Login or Register to read the full post.

[Bognostraclum]

A few months ago there was a 944S2 racer for sale in Belgium.

They claimed 250hp and 1050kg. It went on the market for 18.000 euros.

I have one small res pic of the enginebay, but it's on my hardddrive. Don't know how to put it on the web. Looks like it had a carbon airbox ITB setup with presumably that 9M-valve-trumpet throttle body thingie.

Sadly the add expired.

Partial Post: Please Login or Register to read the full post.

[flash]

250 would be very doable on that one - it only has a single resonance intake manifold stock, unlike our dual resonance manifold - the one on ours gave an additional large chunk of power over the S2 manifold that the ITBs would have to make up first, before making any further gains

in racing though, where 5 hp gains are huge, it could definitely prove useful, especially if it makes more torque

no idea what class that would put somebody in though

Partial Post: Please Login or Register to read the full post.

[Cloud9...68]

Just curious - with the success Porsche had with the 968's dual resonance intake manifold, why haven't other manufacturers run with the idea? Or maybe they have, and I'm just not aware of it...

Edit: Looking back through this loooong thread, I see that Flash asked the same question way back in Post#5. It's as valid a question today as it was way back in 2006...

Partial Post: Please Login or Register to read the full post.

[firefish]

For racing purposes I can clearly see the use of stand alone management and ITB's. Overall tweakability and perhaps also a more predictable behaviour weighs a lot compared to the oddball dual resonance that supposedly is a bitch to tune, requiring lot of type specific knowledge and experience.

For street and mild race applications it would not qualify as a no1 mod but if you are planning to go all the way it may be wise to dwell into the possibility of going that route since many of the tweaks for the 968 are 968 specific and would probably not work on a 'normal' setup.

A 3-liter four turning +7 grand should be able to crank out more than a 100 hp/liter without too much fuzz. But regarding the level of mods required whilst keeping the overall stock design, look a fox944's car, it leeds me to assume that for a near stock car specific features like the intake gives us a considerable gain. For higher level mods it is quite the opposite and is more of a road block.

In the end, the longblock is only a pump and the 968 pump doesn't differ from any other pump out there. With 'normal' intake, exhaust, selection of cams, igniton- and fuel management it is no different than any other comparable engine, like the 2,5 liter evo engine in the E30 M3. All these items being subject to modification anyway if you wanna go all the way.

Partial Post: Please Login or Register to read the full post.

[Bognostraclum]

<!--quoteo(post=78331:date=Aug 20 2009, 03:05 PM:name=Cloud9...68)-->QUOTE (Cloud9...68 @ Aug 20 2009, 03:05 PM) <{POST_SNAPBACK}><!--quotec-->Just curious - with the success Porsche had with the 968's dual resonance intake manifold, why haven't other manufacturers run with the idea? Or maybe they have, and I'm just not aware of it...

Edit: Looking back through this loooong thread, I see that Flash asked the same question way back in Post#5. It's as valid a question today as it was way back in 2006...<!--QuoteEnd--><!--QuoteEEnd-->

Maybe you'll find this interesting [img]style_emoticons/<#EMO_DIR#>/unsure.gif[/img]

Resonance intake manifolds and variable length intake manifold are widespread. Most multi-valve engines have some form of "inlet manifold trajectory alteration" systems. The most impressive system by my own knowledge is the 3 stage varioram on the flat sixes.

Some systems narrow (to speed up gasflow) at low rpm) or widen the inlet trajectory at high rpm (to take as mutch air in as possible). For example the Ford 170hp V6 found in earlier Ford Mondeo's have dual ducts for each cilinder. On is sealed of by a valve at low rpm, but opens at higher rpm's).

Some systems use resonance (of pulsating waves) to create "resonance-effects" like the 968 manifold. Although, as i understand, the 968 has a fixed system. The flat sixes have a multi stage system. It combines, in a sense, both cilinder banks to create resonance. They use connection-tubing of different size (diameter) between the airboxes of both banks. Those "connecting tubes" can be opened or closed by valves at specific rpm-ranges thus allowing mutiple softspots through the rev range. Due to layout, V or boxer engines can incorporate sutch large manifold setups between banks. This is virtually impossible for inline engines.

Also, the length of the inlet-tracts or "trumpets" for each cilinder can be varied sometimes. The Mazda RB26 4-rotor that won Le Mans used continuous-adaptable-length-inlet-trumpets. Trumpet length is important as it favors certain wavelengths of pulses. If wavelength and trumpetlength correspond, magic happens so to speak. The Mondeo mentioned above used what can be best decried as 2 manifolds. One short, one long.

I don't claim everything i said will be 100% accurate, but the genereal idea is true.

Feel free to correct me if i'm wrong, i really like to learn from this. [img]style_emoticons/<#EMO_DIR#>/wink.gif[/img]

Partial Post: Please Login or Register to read the full post.

[flash]

300 has been done, and in fact more than that - i'm definitely not saying it can't be done - all i was saying is that for street application, the gains would likely not be all that much

both the dual resonance and the ITB make gains over a standard manifold by increasing velocity and volume (in fact the sales literature says the dual resonance manifold makes 4lbs boost) - one does it down lower more than the other, which does it better up top - while on other cars you might see 30hp, a near stock car would likely see 10 or so gain, because it already has a 10-15 advantage from the dual resonance manifold - now if you removed that, installed a single resonance manifold, and started from there, like in the S2, you would probably see larger gains

i like ITBs, and have used them in the past - using them now on the M3 - VERY effective - just not so sure how well it is going to work on this engine, and whether or not it is worth the time and money

i am further complicated by the fact that it would never get past emissions, and therefore limits itself by default to a race car, and since i would be supercharging that..........

Partial Post: Please Login or Register to read the full post.

[Bognostraclum]

<!--quoteo(post=78348:date=Aug 21 2009, 05:02 AM:name=flash)-->QUOTE (flash @ Aug 21 2009, 05:02 AM) <{POST_SNAPBACK}><!--quotec-->300 has been done, and in fact more than that - i'm definitely not saying it can't be done - all i was saying is that for street application, the gains would likely not be all that much

both the dual resonance and the ITB make gains over a standard manifold by increasing velocity and volume (in fact the sales literature says the dual resonance manifold makes 4lbs boost) - one does it down lower more than the other, which does it better up top - while on other cars you might see 30hp, a near stock car would likely see 10 or so gain, because it already has a 10-15 advantage from the dual resonance manifold - now if you removed that, installed a single resonance manifold, and started from there, like in the S2, you would probably see larger gains

i like ITBs, and have used them in the past - using them now on the M3 - VERY effective - just not so sure how well it is going to work on this engine, and whether or not it is worth the time and money

i am further complicated by the fact that it would never get past emissions, and therefore limits itself by default to a race car, and since i would be supercharging that..........<!--QuoteEnd--><!--QuoteEEnd-->

What about EGR and a custom ITB setup? I guess combining those two would be very difficult but it could help with emissions [img]style_emoticons/<#EMO_DIR#>/unsure.gif[/img] .
I don't know if the Euro-spec BMW M-engines have something like this but i suppose some do? [img]style_emoticons/<#EMO_DIR#>/unsure.gif[/img]

Partial Post: Please Login or Register to read the full post.

[flash]

quickly explaining emissions laws, they really have less to do with what comes out the tailpipe than they do the political and bureaucratic shenanigans that went on as they were put in place - as long as the automotive industry and oil lobbies can get their hands in it, we'll never really have good emissions laws

but back to the ITBs, we know more air works, though it then takes more fuel - i think the major hurdle here is going to be the then necessary stand alone ignition system - that makes it a pretty pricey package for the power gained

but who knows?

Partial Post: Please Login or Register to read the full post.

[Cloud9...68]

But I wonder (and it's only idle daydreaming, because I can't ever see an ITB for the 968 coming to market), based on LHP's comments, whether a substantially larger gain than 10-15 hp couldn't be possible with an ITB when combined with RS Barn's Stage 2 or even Stage 3 head, RS Barn's performance cams, Stage 2 or Stage 3 chip, and of course the headers and cat back. In other words, with the engine set up for optimal pumping efficiency, could an ITB possibly take it from the 285 - 300 hp range achievable with the above mentioned mods, up to the 330+ ballpark? And according to LHP, much of the gains can be in the mid range (which I admit sounds counter-intuitive).

Partial Post: Please Login or Register to read the full post.

[flash]

330 is a reach, but i have heard of one at 325, and was with an ITB setup

the engine was a very serous race only engine - completely unusable on the street,and had to rev well past 8k to get that power

again though, larger injectors are required, and stand alone ignition - i don't think it ran very long either

at this displacement, even at 300, things get dicey - 285 is about the cap on these injectors, and at that it requires some significant fuel supply changes

at 3.0 displacement, with everything thrown at it, in street trim (such as it might be), i see maybe 295 - at that level though, there will still be some compromises in drivability- it will never run in cold weather, and won't likely run well in hot

for street use, i think a 3.2 with a flow matched head, and the mods we already know, is going to be the setup - that should make about 300 reliable hp, with gobs of low end torque - we should be able to use the factory electronics with a custom chip, and one size up on injectors

all that being said, ITBs on a well prepped 3.0 race engine should make a solid 310 or better

Partial Post: Please Login or Register to read the full post.