[94SilverCab]

Yes, Weltmeister, Promax are the 2 that come to mind...RS Barn was best in "The great Chip Shootout"

 

Jay

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[Roboman]

There were a couple of other chips made in the earlier days.  I had a Weltmeister in mine and it worked very well.  I still have it in the garage somewhere...

I'm intrigued rxter, why did you swap out your chip, did you put on an SC or something?

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[Rolls912]

I completed the airbox mod & snorkel delete today. Thanks for the info. 

 

I feel the throttle is more responsive. I do like the slight louder induction sound. I don’t need to look as often at the tacho.

 

I also fixed the sump leak. The under-trays are an absolute PITA! 

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[Waylander]

All that destroyed air box and more noise for 5bhp,


Why bother, if the cars not fast enough buy something else, plenty of fast cars for less than a pristine 968 is worth


I personally just cannot see the point of all this horsepower hunting, its just a waste of time money and effort, and hard to get parts


The sump gasket has metal spacers in, so just nipping the bolts is a waste of time

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[ds968]

For those people who are not in the least bit interested in keeping the car in exact original condition to enter it into concours contests , or keep it as a garage queen, and hesitant to drive it like hell until the wheels fall off ( which IMO would be a pity not to do ) while  holding on to a faint hope that someone, some day might pay a higher price for an untouched 968 pristine sample, even the smallest modifications which offer at least some visceral benefit are well worth it, IMO.  I doubt anyone who does the chip and / or air box modification worry about making the car faster, it’s all about better throttle response and a bit of an increased “the car is alive“ sound, for maximum driving enjoyment.  People spend up to $ 1,500  for Drive-by-Wire kits who offer absolutely nothing more than a “placebo” performance effect, just a livelier throttle response, so why not this option for the 968 ?  IMHO . 

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[J.Elenbaas]

A bit of an increased "the car is alive"sound you can get easily.

Just take away the complete exhaust system, it gives you a bit more noise and you safe at least 10 kg on weight.

And when you drive off it surely give you the idea it's meaner and faster

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[Roboman]

I'm in there with DS, I doubt anyone is going to this effort to increase the drag speed. As Waylander says, the hp gain is just not worth the effort. However, a better sound is a nice gain, after all people spend good money on tuned exhausts, as is a slightly livelier response. So, for the minimal cost and effort then why not?


DS there is another reason for keeping the car as original as possible... I'm handing mine on to my nephew. I guess it could be argued he might like a fully blown version, and I have thought about bolt on SCs etc because one can always unbolt them. I guess I don't have the motivation, as I said many moons ago, I wish I had discovered real racing in my youth.


For my own part, I visited my brother and son yesterday and picked up the air box I bought six months back. (I went past Waltham Abbey on the M25 and it did occur to me to call by, but given I was already on an 8 hour round trip I decided against; maybe next time Waylamder). So now I can consider some modifications to smooth and improve the airflow into the MAF. I have no great ambitions, I just like to experiment.


But before that, when I get back home I need to replace my brake booster....


Enjoy your Sunday.

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[Rolls912]

I’m absolutely delighted with the outcome. Now, I can actually hear what’s happening. Before, it felt like I was driving a sterile turd .

I’m not remotely interested in trailer queens. Been there, done that.  My car is completely original otherwise and I’m very happy with that. And at the end of the day, it’s what makes you feel good that counts.

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[Rap]

Oh good lord all this blah blah blah about this that or the other thing. Even with a highly modified track car most cars today are faster on the track. Even with a modified garage queen most cars are faster. Do we forget why we do what we do? I was at a cars and coffee yesterday, it was raining, and parked across from a ruf carrera gt. Amazing looking car. When I open my hood guess who got all the views?

Do what you want cuz it makes you feel good or happy. Air box, sc, koni’s, strut tower brace, splitter, exhaust all make the car better. Worth the cost? It’s your pocketbook. Beauty is in the eye of the beholder. These cars are unlikely to ever appreciate as some others have. However, you do have a car where only about 4600 were imported into North America. Because of educational deficiencies most people don’t understand what that means. It means a low production rate car. Revel in that and enjoy your car. 

incessant chatter about the value of this or that should be consigned to some other car forum!

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[Roboman]

Even fewer Cabs eh?

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[dlearl476]

I modified my box a couple of years ago. Did a miracle happen?.....no, but the sound changed a little and the power improved a little...I am guessing about 5hp...and that was it. It is easy to do though.

I did the same, along with adding the chip Flash et al designed. Was it the cart or the horse? I don't know, but my "butt dyno" noticed a significant increase in power, especially with 94 octane fuel. Plus, it sounds glorious. But then, I think my Ducati with FCR's and UNI pod filters sounds glorious, too.


MCL-Goodjob on the "velocity stacks." I thought about using the ones out of my now-discarded Ducati airbox, but there were only two. (Duh). I opened my box according to Flash's write up and lucked out to find some kind of Venturi-type plumbing fixture that just so happened to fit the holes perfectly. So tight, in fact, I didn't even bother gluing them in, and they're still in place some 12 years later.

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[snova]

I have a 35 mi back roads route that I take all my cars on to get some spirited exercise. When I made the mod using a 2nd used airbox, it sounded slightly better.  Acceleration was better for about the first 7 mi or so.  The more I drove the more sluggish the car felt.  At around 25 mi, performances seem to be worse than with the unmodified airbus with snorkel attached.   Long story short, it was fun experimenting and has some interesting gains when the engine bay was relative cool. I have since put it all back to the stock airbox and snorkel.  It was fun to try and quite educational. 

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[Waylander]

Hot air is the big problem, you need to keep the heat away from the air box with a RSBarn shroud

 

every 10 degrees robs you of between 10-20 bhp 

 

so the mod works great in the winter when the cars a put to bed, and crap in the summer where the engine bay temps get to about 50 degrees C

 

Just ask yourself why turbo cars use an inter cooler 

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[flash]

i am just stunned that this is still a topic.  i got an email telling me about it, and it just boggles my mind.

 

while it is true that heat is the biggest enemy on mods like this, it is not nearly as bad as what is being touted here.  i did EXTENSIVE testing on this, with multiple temperature probes, in multiple locations, in multiple driving conditions.  the intake temp is the same as the engine bay temp while sitting still, or at extremely low speeds.  as long as you are rolling at a speed of about 20mph or more, the intake temp is essentially ambient.  some testing showed temps actually went down.  recovery is also only about 1 second.  this makes temperature relatively a non-issue.  if you are experiencing lag or power loss, the problem is likely elsewhere (like low octane fuel, which would cause the ECU to retard timing, costing a lot of power)  the wrong spark plugs can also affect this.

 

the key to the airbox mod working best is to use the early trim piece that closes off the entry point from the rest of the engine bay.  also, you have to make sure that ALL intake entry air is coming from a cool location.  the snorkel works against you.  fluted port rings (no square edges) are the best here, and deleting the snorkel.

 

also, just as a math note, relative to intake temperature, power increases and decreases on a normally aspirated engine are only 1-2hp for each 10 degrees,  not 10-20.

 

again, read the article, and the thread that relates to it.

 

just as a side note, turbo cars use intercoolers because the temps are increased by anywhere from 30-100 degrees under boost, depending on boost level.  it is a whole different world.  it's like saying covid is like the flu because you get a fever with both. (sorry - couldn't help myself there)

 

we now return you to your regularly scheduled programming

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[Waylander]

Why bother, Bob you have left all this behind


And I got my numbers from Adrian Newey of red bull fame

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[ds968]

And I got my numbers from Adrian Newey of red bull fame

No doubt one of the most accomplished individuals in the automotive world, BUT no two brands and models are created equal ; my 968 , while with the previous owner, was serviced for a couple of years by ( then retired ) Buddy Laziers’ crew’s chief mechanic ;  Mark -something, I can’t remember the last name, who opened a specialty car service shop .. He was friends with the PO, and worked on his cars, including MY 968.  Even he admittedly had to learn the peculiarities of the 968 , said something about the unique “pulses“ which threw him off because he thought it was essentially the same as a 944s,, etc..  So the  “ a car, is a car, is a car “ adage  doesn’t always apply .  With all due respect to illustrious folks like him or Adrian Newey,  I’d much rather take the advice of someone like  Bob ( Flash ) or Pete ( at RS Barn ) who have poured their blood sweat and tears into the 968, with specific and focused research, testing and development of products for it , giving them an unmatched wealth of experience about these cars in particular , as opposed to someone in the Indy or NASCAR or F1 worlds, or other race cars building domains, who may simply make educated assumptions re the behavior and response of cars to various conditions, but in a very general sense .   Just IMO. 

 

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[snova]

did some reading.  It seems the HP adjustment coefficient is a PERCENTAGE of the overall SAE J1349 rating.  Not an absolute HP number.  Which makes sense to me.     The change between 100HP engine and a 500HP engine  operating at two different temperature shouldn't be the same in terms of absolute HP.  

 

http://hpwizard.com/engine-horsepower-calculator.html

 

Using typical barometric pressure and altitude values at the link above, using 4 cylinder engine with roughly the displacement of the 968 motor I am seeing about 2%/10 degrees F.   i.e. about 5HP (roughly  2% of 968's 237 HP rating) change for every 10 degrees F.  Roughly double that if using degrees C instead degrees F; which is what I think Waylander was saying. 

If I double the amount of cylinders to 8, aka doubling the displacement and power potential it becomes about 10HP / 10 degrees F.    Percent remains at around 2% / 10 degrees F  or if you want it in degrees C it would be almost 4%/10 degrees C.  

 

For those curious, you may want to play around with the variables in the calculator above to see what happens when you change temperature and displacement.

 

 

last point think is important to make.  I could be wrong but I don't think the 968 NA design is a "ram air" type design. I don't think any air is being "forced" into the air box by pushing air as your drive. I am assuming the air is being "sucked" into the air box by the engine using the intake strokes.  aka "induction"

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[Waylander]

Yes its a suck job, no real ram effect, too much in the way

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[Chris Vais]

As most of you know by now the RS Barn is closing up shop. I went to the website to see if I could purchase an airbag shroud, but it appears that there are none left to purchase. 

 

So, does anyone have an RS Barn airbag shroud that they would would be willing to cell?

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