[ds968]

You're really that " sure of what the results will be " ? Ok, but since dyno charts are always subject to debate just as you said in your post, let's skip that and do a real test by running my car head to head with..say, an SC'd 968, which ostensibly should have 30 or 35 more hp and ft/lbs than mine. Remember, I 've already tested this head to head hypothesis on a few trial run with fairly even results, but we can have another, witnessed contest with a car and owner able and willing at the next Paso meet, and from a rolling start (you can pick the start point, whether 20 mph, or 40 mph, or whatever..) and run them flat out on a straight half mile distance to see just how they fare against one another. IF at the end of that half mile my car is fairly close to the other one, which I am convinced it will be..it may be tough to debate that anything other than the BB could make up for a large part of the delta between the two cars' power.. and a decent bottle of wine is on the table..so to speak...







,

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[flash]

now you're skating the issue. the issue is not whether your car is faster than another. it is that there are torque losses with the B&B.



dyno charts aren't what is open for debate. they are extremely good tools. the problem is how people who don't know how to read them, or how to conduct a test and eliminate variables, misinterpret what they say.



case in point: you can't compare one car to another to show losses in a cat-back. you have to test on the same car with before and after tests. it has been done with a number of them, but if you want to do it on yours, i am happy to finance the project, and let you pay for it when i prove i'm right. it would be a bitter pill, but at least then you would have the proof for yourself that you refuse to accept from those NOT selling something, that have already done this.



that was no kind of test, but by the way, when we made that run, my kit was not working nearly properly, and in fact, it was quite wrong. it was really stumbling. i'm a bit surprised that i didn't blow it up. that problem has since been resolved. i promise, it wouldn't be close. but, if you want to take a shot at it now, we will weigh the cars and even them out, and then the race should be in top gear, from say 40-50mph up.

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[clivehuggins]

[quote name='mdss' timestamp='1320856237' post='117745']

Hi guy very interesting reading indeed, i have to say that i can clearly feel more power without the cat and having spoke to a few 968 specialists that race the car in the porsche series here in the UK they all seem to run the car with no cat. They simply weld in a pipe which i am going to have done on friday as i think the resonance i can hear is the second skin(internal) rattling.

I will report back. I do trust what flash says though as yes when between 2000-4000rpm range the car feels a little slower but definately better at the top end.

[/quote]

I've been reading this thread with interest as my 968 has had its cat removed (prior to my ownership). I have carried out the airbox (incl K&N) mod and can say that after doing this the exhaust noise improved considerably, and perhaps a bit more ommph. I've read that others consider the exhaust note to be disappointing, mine sounds great imop, bit like a gruff V8. The cat is not a necessity here in NZ for a 1992 car so I guess unless there was a compelling reason to fit one again (a value for money gain in bhp, or potential engine damage without it) then it'll be left that way. Does the ECU automatically compensate I wonder?

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[ds968]

Lol, so RS Barn who supposedly is the only place that did this before and after test on the BB system itself, was NOT selling something ?! I'm not implying at all that anyone would misrepresent the results, just responding to your comment re unbiased, independent testing by a source that does not have a comparable/ competing product to sell. But I understand what you're saying also; it makes little sense to open a never ending discussion and debate of variables. By the same token I have also not seen anything form another independent source that either supports , or disputes BB's assertions of those very levels of hp and torque increase, but I would think if what their claim was not fairly close to reality, places like Borlla, Magnaflow, etc..would jump at the opportunity to challenge and discredit them, in a market where competition to sell exhausts for Ferraris, Vettes, Porsches , etc is fairly intense and very much in the public eye and where credibility affects everything ; if you can poke holes in it there's a lot at stake to lose.

Anyway, people can do their own research and draw their own conclusions on gains or losses with or without a gutted cat, or with a free flow catback, or whatnot..

My two cents are in and spent on this topic,

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[mdss]

I didn't realise that i would open a can of worms like this, lets not argue guys, the fact remains that provided each of us is happy with our cars and the way they run thats the main thing, life is too short to waste time arguing.



sorry if i have caused a dispute.

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[ds968]

No problem at all, this group has many healthy debates on many topics, they're all civilized, they're all respectful, hardly anyone I know takes anything personal, I know Bob does not ( since it' s never meant in that way to begin with.. ), so it's little more than an expression of different opinions and personal experiences , and while all of us concur on an overwhelming majority of things on this forum, there will be occasional issues where we agree to disagree. ..hell, we 've done that more often in person and then had a glass of wine or two.. So no worries about "starting " anything..

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[ds968]

P.s. You should have seen some of the threads on the old forum..LOL.. In some cases merely logging in was cause for some personal tete-a-tete to start.. Ok, I exaggerate ...but not by much ;-)

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[flash]

pete was not the only one to see the same losses on the B&B. i have seen 3 different independent tests and they all show EXACTLY the same kind of loss in EXACTLY the same place. the midrange loss is undeniable.



claims are easily spun. you could say that a system made "x" hp. that doesn't mean it does that across the board, or that it ALSO doesn't lose torque in the middle, or down low, or somewhere else. basic exhaust physics will tell you that opening up flow has the potential for upper end power, but at the expense of low end torque. corking it up has the potential for increasing low end torque, but at the expense of upper end power. finding the "perfect storm" is real science, and always a compromise somewhere.



the anomaly of this car is the weird spot in the middle that always shows torque loss when the system is opened up, and is a result of pulse timing and the resonance of the 2 different intake runners. they just aren't happy there.



that doesn't mean that upper end gains can't be made.



how exactly would somebody dispute a manufacturer's claim? just because nobody has publicly challenged it in court does not mean that the claim is false. a different manufacturer would not challenge the claim because it would cost them too much to be able to support their own claims, let alone lead a charge against another company. performance claims that are unsupported by testing is a very common practice in this industry. none of them really do testing like you think they do. there is no reason to do it when the public is as gullible as they are. the buyer wants to believe the claims, thereby justifying the expense, so they don't actually go out and test anything, or even do any real due diligence to verify the manufacturer's claims.



the bottom line though is that you can disagree all you want, but you would be only be ignoring proof. i've done this test myself and seen the results. i threw away the B&B that i bought because of it, because i drive in the middle, like most people, and was not interested in peak power. i am trying to find my charts, but i think they were on the old computer that is now in a landfill somewhere when that hard drive crashed 5 years ago. either that or they were on hard copy only and i just can't find them. i can't remember. there was so much testing going on back then that it was hard to keep everything organized.



if i have to go out and buy another one, and run the test again, just to finally put this to bed, i will. i am that positive of the results.



i'm thinking of raising the stakes.

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[94SilverCab]

We all know that Dan doesn't care about anything other than Peak Power..the only time he's in the middle is when he's zoomiung up to peak...



BTW, I've sent an e-mail off to B & B asking them directly whether they make any horsepower claims for their cat-back systems...I will let you know if I get a response.



YMMV,



Jay

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[flash]

yeah - i had that very conversation with them a few years ago, and i am pretty sure i posted about it at the time. they said no documented gains on the 968, that they had never actually tested it on a 968, and that they had only tested on a 944, which as we know is an entirely different animal.

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[bombfactory]

As I am about to embark on a 968 cat-back project with a friend of mine who runs a local performance exhaust company, I'd be interested in seeing a dyno graph for the B&B muffler, if anyone can find it, for comparison.



It seems to me Porsche really did their homework with regards to the 968 exhaust system, finding the 'sweet spot' that doesn't sacrifice too much midrange torque for hi-end horsepower, and vice-versa. Since most of us here have modified our cars in one way or another to 'make more power', it would be good to know, since a cat-back muffler is a fairly standard and popular performance upgrade, which products do what, and where in the rev range.



I, personally, am suspicious of ANY product by ANY manufacturer that claims to make power, but doesn't show a dyno chart to back it up. If it really performed as advertised, they'd be crazy NOT to use documented proof - a dyno graph, or maybe multiple graphs from different cars - to help sell the product.



Having read through multiple muffler threads here on the forums, I have no illusions that a 'magic muffler' exists for the Porsche 968 - one that makes more midrange torque AND hi-end horsepower. Accepting that, the goals for my system are a bit less lofty: Better looks, better sound, better throttle response, lighter weight and no (or minimal) loss of torque as compared to stock, while breathing a bit better up top. We'll see...

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[flash]

i have at least one. again though, it is only relevant for the car on which it was tested. you can't use the chart from one car to match up against a chart from another car. sure, you can look at the shape of the curves, and that part is fine, and will tell you about peaks and valleys, but you can't compare the numbers. you have to test all of the systems on the same car, under the same conditions, in order for the results to be valid. otherwise you have too many small variables that result in inaccurate readings. remember, we are only talking about 2hp, so small changes put you in the tolerance range of the testing equipment.



that's exactly why the charts have never been posted. nobody wanted to get into that discussion again. when i did the chip shootout test, and the airbox testing, you should have seen the nonsense that was put out there by those who don't understand these things.

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[mdss]

Hi guys the fact i have gutted my cat leaves me with little choice other thangetting a pipe welded in for now until i find another good condition cat. So my question is this if i simply leave the rest of the system standard should i have the guy put some kind of muffler in place of the cat to create a little more back pressure or should i simply have the pipe welded in.

This thread is mind boggling i am an economist by trade and stare at charts all day that most would find difficult to understand but this thread beats anything. Maybe Ben bernanke/Geitner should speak to flash!!!!!

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[Rap]

I bought a 968 and had RS put a chip, air box mod and new cat. The previous owner was driving with me and said to me that wow this car feels different and faster. I am not an economist or an engineer and Bob drove in my car after the mods were done. Between myself and the previous owner changes were felt. No charts to document this just feel. I suspect if you asked most guys who did these mods if they felt a difference that justified the outlay the answer would be yes.

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[bombfactory]

Flash you are right - a graph from another car would have no real bearing on my own car, but could be used as a case study to see where potential problems arise when attempting to change the exhaust flow.

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[mdss]

The mods you list are similar to me the airbox mods(flash) and promax chip now i am just wondering whether to have the straight pipe fitted instead of my now dead cat or amuffler in its place to produce a little back prssure or maybe have a brand new cat put in the old cats place.This is possible as the fabricator said he can retro fit another cat to the down pipe. Or will a new retro fitted cat be inferior to the porsche cat?

Thanks for the insight

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[flash]

inferior is relative.



the porsche cat is extremely good at cleaning up the exhaust. aftermarket cats aren't.



different cats have different amounts of restriction. this changes the flow characteristics accordingly. there is no data i know of to tell you though in CFM or Hg as to what they do.



another thing to consider is that the less resistance, the leaner you will run. this may or may not be a concern.



i tried a few aftermarket cats and the only one that got close to providing enough resistance was a huge double brick monster. all of the others exacerbated the midrange torque drop, with the least resistant making the biggest drop.



that being said, the less resistant i made the system, the more responsive and freer revving it was up top.



no free lunch.

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[bombfactory]

Flash - a little off topic here - the 968 engine seems to rev fairly well once you're up in the range, but down low and off-idle throttle response seems positively glacial. Is this mostly the heavy DM flywheel, or are there other contributors - and can they be improved?

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[flash]

lots of stuff responsible for that, not the least of which are the really big cylinders

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[ds968]

I located the dyno results BB sent with the catback shipment, so will scan the documents and post them on Monday when I get back to the office.



They sent both a 1988 944s test ( not sure why ) and a 1995 968 results, but they informed me because that car had rather low rwhp readings ( stock numbers ) a subsequent test was done on a 93 or 94 968 and they'll send that as well, but either I did not receive it or they never sent it.. do not remember.



Anyway, I'll post what I have from them next week, for whatever it's worth to others..

BTW, I'm sure there will be a million and one explanations for all the numbers claimed, and/or lack therof..



It's been made very clear that each car is different, so another 968 could have had a lot higher numbers than the one BB tested, or for that matter a lot lower numbers, so the old saying applies : " YMMV "



Take mine for example, every Racer-X chip tested in 968s shows power gains continuing beyond 6600 all the way to 7150, IIRC. In my car, the Racer X chip's power band drops like a rock at 6600.. explain that ! That's just one more reason I don't put as much credibility on paper results for any given car or even a bunch of the same models, and rely solely on validating those "findings", or disputing them with pure live testing results / experience.



I don't care to debate this further, it serves no purpose to me, so I'll post the stuff I got from BB just so others can look at what they provided and do whatever they choose with that info - throw it in the trash, or call BB, or whatever..

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