Russ L.

Good day from sunny[I wish] snowy,rainy miserable Long Island N.Y.
It seem to me that my 3.2 feels like I'm waiting for the "turbo" to spool up before she starts to make any real power. [ she's non-turbo]
Steve Weiner suggested to me that I upgrade to 3.6 cams..."and that will bring up the power a tad"...
Any other suggestions out there?
Thanks to all
Russ

JackOlsen

Have you already done the chip/exhaust mods?

Russ L.

Jack I've done nothing...Don't get me wrong...she runs great, but I'm a tinkerer LOLOL! She's a euro 84' cab and appears to be untouched and unhit at all...No signs of bodywork but it did have a respray about 6 yrs. ago.

Steve Weiner-Rennsport Systems

Russ:

LOL,....My best advice is not get the "cart in front of the horse",....

Do things in order so you do not waste money and expensive labor.

For improved engine performance:

1) Chip

2) Exhaust upgrade

3) Airbox modifications

4) Cams (964)

5) Extrude-Hone intake manifolds

6) Displacement increase (3.4 or 3.5)

7) Twin-ignition

8) Tall Butterfly intake system w/DTA engine management

As you can see, the possibilities are only limited by what you wish to do and your budget for attaining those goals.

I must say that suspension should always be the first upgrades to do.

JackOlsen

And if you take a step further back, Steve would also probably tell you to think about shorter gear sets (if the 915 is going to need work anyway).

Is it a street car, or track/AX and street combo?

There are a lot of areas you can tinker with to make the car quicker.

Russ L.

My GURU LOLO!!! Steve soon I'll Have a book from picking your brain!
O.K., First I've printed all the recommendations you've sent me about the susp. and will put them to use when the weather lets up and I get my garage built in the spring.
2 I just printed this list and have a few questions...The #5 manifolds...is this anything like the old big ball bearing in the formula-vee
trick? Meaning we used to "spread the interior wall of the int. runners out with a large ball bearing ?
What the heck is a tall butterfly int. system?
Any rec. for what chip I should use...there appears to be a few...and "dyno specs." can be fudged as well.
The jug replacement is gone over in the performance handbook but
I don't think I'll be seeing that until the car is sorted out or maybe when I find a coupe that could be "tracked".
Will a cab chassis hold up to these mods. without twisting?
Thanks Russ

Steve Weiner-Rennsport Systems

LOL,...Indeed, I always recommend close-ratio gears before any serious engine mods are contemplated.


I tell people wanting to go faster:

1) Driver Training

2) Suspension upgrades (and seats/harnesses)

3) Brakes

4) Close-ratio gears

5) Engine mods

For folks doing a fair number of track events, its prudent and cost-effective to have an extra set of wheels for some track tires.

Steve Weiner-Rennsport Systems

Hi Russ:

LOL,...Well sir, I AM working on such a book.

1) Carrera intake manifolds are well known for uneven flow from branch-to-branch and we used to cut them apart and massage each runner by hand until they all flowed the same on our flow bench. Now, we use the Extrude Hone process to accomplish the same thing. We just check them on the bench after this is done to be sure that they all match.

2) A tall butterfly intake is a 6-stack intake system as used on Porsche race cars. You can see some examples of these in Bruce Anderson's Performance Handbook. We now make our own and use an Engine Management system, instead of the mechanical FI that those had. Its not for cars that need to comply with smog laws.

3) There are several makers of chips and you should do your homework on that. Get one that reatins the stock rev limiter unless you upgrade the internals.

4) There is no question that a coupe is a better candidate for any track use, but your cab will do just fine as long as you do not go crazy with chasssi mods and follow some good sound advice in this regard,....

If you get really bitten by doing DE events, I would suggest a non-sunroof coupe of some kind for its lighter weight and greater rigidity.

Russ L.

Thank-you all again...I sound like a broken record lolol...
Jack I didn't see your post when I went off...Sorry... No , the car is going to be
a street / A/X machine due to a few reasons : she is very clean ,it's a cab
and a cage would ruin the look ... and my wife would kill me if I turned her into a "cut up monster" .
That's why I've been trying to grab this 3.0 targa I found this summer.
The top leaks and the pass. floor is becoming a fishtank...but the chassis is sound and it appears to have been left sitting out in the hamptons for a while in a field...Who knows what they want for it!! At least if I lighten her up and cage it ...you wouldn't know what's been done to her until I crack the throttle.
Steve....I'm taking all this info. and listing everything!
Tell me ..what kind of h.p. boost can be found when changing the jugs to a 3.5 lets say ...and wouldn't I have to do some rod bolt mods as well?
Russ

Steve Weiner-Rennsport Systems

Hi Russ:

A 3.3 litre (SC motor with 100mm P/C's) with CIS and 964 cams with twin-ignition should make around
230-240 HP with the right exhaust and good heads.

A Carrera motor with 100mm P/C's (3.5 litres), twin-ignition, 964 cams, custom chip, and a proper exhaust does around 250-260 HP.

The shape of the torque curves between the two motors are VERY different,....

nolift911

Steve,

I have an 84 Carrera with a chip, cat-by pass and a single in dual out RUF exhaust. I was interested in what you refer to as an "airbox mod". What does this consist of?

As for the shape of the airbox what are your thoughts on airflow for a "faceless" airbox vs the cone setup?

Also as for flowing intake runners what is involved with that taking the intake off and shipping to you? Any other mods to realize this gain? Also with the 964 cams is this just a swap out or is ther DME tunning involved?

-Jeff
nolift911@hotmail.com

Steve Weiner-Rennsport Systems

Hi Jeff:

Aside from santizing the engine compartment, those cone filters do more for noise than power,...

I simply drill 6-7 1.5" holes in the air cleaner cover. One can also cut away the cover and leave enough material to secure the flat panel element.

Its not tough to remove the intake manifolds. Juts pull the aircleaner, airflow meter, disconnect fuel lines, throttle linkage and assorted hoses. Unbolt the flanges from each head and voila',....you're done. You need to separate each half and them wrap them in bubble wrap and box 'em up.

964 cams are an easy swap. Since each engine is different, I'd certainly put the car on a Dynojet and see what the A/F is under full load.

nolift911

Excellent. Thanks Steve. I took my table saw to my airbox lid, turned out very well. I had heard the there were turbulence issues with the flat panel instead of the cone design from some other folks.

Sounds like a winter project for the intake manifolds if the gains are worth it. From the other mods and the ordering it looks like that would be next on the platter for some modest gains.

-Jeff
nolift911@hotmail.com

r911

Just remember, except for the early smog years (say 1975-83) it takes a whole lot of work to get more out of PAGs engines than what they put in.

If your approach is that it's a fun project even if hp gains are minimal you'll be fine. But these aren't Chevy's -- there is not a lot to be easily gained. If you want to build a race motor, sure. That's not cheap either.

An interesting question with the airbox lid mods is whether it now draws in hotter air, and thus actually makes _less_ power. I don't know that any one haw ever measured that, but it's something to think about. A ducktail will introduce some cooler air.

Steve W

With hotter air, it is definitely possible to realize a reduction in overall power. Contained within the software of a stock Motronic chip is the function to retard overall ignition timing based on a factor of the intake air temperature. This is part of the reason why there is a temp sensor within the Bosch air flow meter. The ignition can be retarded as much as 4 degrees. However, along with a reduction in ignition timing is a reduction fuel, as hotter air is less dense and thus requires less gasoline to maintain the stoichiometric ratio. The combination of the two will definitely work negative against you. This is why under hot weather, our Carreras don't seem as fast as when the weather is cold. Ever touch the air flow meter on a hot day with your AC on? However whether these principles apply to a cut open airbox, I don't really know as it is difficult to test. This is probably one bit negative chalked against a Cool Collar. At velocity though, the air buffering through the engine compartment should have a cooling effect over the warm static intake air such as when on a dyno, so that final afr ratios are sometimes best dialed in with a wideband sensor at full throttle on the road. Rear tails such as the ducktails Randy mentions will also have an influence on the air temperature and pressure introduced. Whereas a tailless 911 will typically measure light vacuum behind the car, a tail equipped 911 would actually measure some light air pressure under the tail. Perhaps the best solution to a better intake filter system is an elbow of some sort that draws air from right under the decklid vent. The mouth shape should have a trumpet shaped flare such as on velocity stacks - for maximum flow and mimimum noise, and should taper down and gradually meet the square opening of the Bosch air flow meter. A cone filter of some sort should then be attached to the intake mouth.