shudder update

[jrkrider]

i just wanted to let everyone on the board know that my shutter is completely gone!if you remeber when i first bought my car it had an extremely bad shudder like almost dying. i went to www.spiralmax.com (there the place that says supercharge any car for 69.95) well for those of you who dont know it goes in your air tube to the airfilter and it swirls the air so you get better air flow to the car which results in better gas and allitle better acceleration and for the older 944's the shudder is gone. i was so happy that i got one of these. i hope for those of you who want to get rid of your anoying shudder will try this. for 69.95 plus ten dollars off its a good thing. if anyone is interested please e-mail me or reply so i can tell you exactly what to get.

[AFJuvat]

Quick tutorial -

I'm simplifying this, but it should serve for illustrative purposes.

There are two basic ways to increase performance in an engine:

1. Increase fuel flow
2. Increase air flow

Fortunately, in our cars, the DME handles most if not all of the fuel delivery and timing, so that pretty much limits us to increasing air flow (yes, I know we can muck with the fuel flow, but we all know what a PITA it is).

Best ways to increase airflow are:

Free flow air cleaner - cheap, small benefit
Port/polish intake - rather expensive
Free flow exhaust - depends, seldom less than $500
Forced Induction - Expensive

Forced induction literally rams air into the intake - A turbo uses exhaust gasses to spin an air pump. This pump takes a large volume of air and forces it into the cylinder. The exhaust gasses are then dumped back into the exhaust system.

Supercharging is similar, but is driven by a belt rather than by exhaust gas and is thus more responsive throughout the entire RMP range.

Looking at the spiralmax, it seems like it would restrict airflow rather than enhancing it. I can't see any benefit by putting one in the air intake (pre-filter) because the air cleaner would stop it. Then again, I cant see much benefit by putting them in the intake boot either, the design of the intake manifold would again break up any perceived benefit that twisting the air would accomplish.

Sorry, I just can't see how it would work - it isn't doing anything to increase airflow.

AFJuvat

[jrkrider]

your probably right( i dont really know anything about cars) but all ive done is put this in my car and its running a whole lot better.
it seems alot smother in lower gears, in your post i didnt really understand what you were saying(because once again dont know much about cars) but whatever it does it seems to be working.

[ae1969]

you have to love this quote on their webpage

"Typical range of improvement over baseline is:
0 to 35 increase in horsepower,
0 to 31.85% increase in fuel economy"

I would probably lean towards 0, and it should maybe have read
-5 to 35 increase in horsepower,
-5 to 31.85% increase in fuel economy"



You probably loosened something while dismantling your intake that allowed some proper air flow...... but if it makes your car happy.....keep it

[todwic]

...you'll prolly just throw them back at me anyway.
My theory why it probably seems to fix the shudder:
Mr. Wilk explains why the shudder exists
here. I haven't caught F.R. in an error, and the advice he's given me has been right on the money, so I'll endorse him as a knowlegable person that knows from which he speaks.
I think the spiralmax item (also sold under another brand:The Tornado) restricts the intake air flow so that by the time the engine would have shuddered under normal circumstances, the "restricted" car has just begun to catch up with the DME and the DME and the Intake sort of "meet in the middle". This reduces the shudder to near imperceptivity.
I have two real life examples that that I think help back me up on this:

1. When refilling ink cartriges for the printer, you pull back on the plunger and hold it untill it fills with ink. If the "needle" of the syringe was larger, it would take less time for it to fill the barrel.
   
2. When my chevy Luv fouled out a sparkplug, as it was want to do, when I would floor the pedal, it would take longer to build RPM's, and when I took let off, it would take longer for it to work it
   's way down to an idle.

That's just what I think

[jrkrider]

that makes sense i dont really know anythin about the airflow but it has seriously helped my car no more rough low gears it runs great! i hope someone else who has the shudder would try one i told spiralmax and there sending me decals and stuff. people might not think this works but for my car its been a miracle and i support spiralmax 100 percent.

[todwic]

Great 4 you! I'm glad you have '44 runnin like you like her.
I watched 3 hrs of an infomercial on the Tornado, and I have to say it looks impressive., and the #'s they gave were quite impressive, and if you believe, JRK, then by gawd Virginia there is a Santa Clause
Best of luck to you and yours!

[Taz's Master]

Here's my 2 cents.

First those horsepower numbers aren't necessarily bogus.
Horsepower is measured on a curve, many many performance-enhancing modifications profess to increase horsepower by x # of horsepower, and actually reduce the area under the horsepower curve. They simply outperform the stock engine on the dyno at one extreme end of the hp curve. Meaning that when a product is advertised as giving you 10 horses, that doesn't mean you get them across the curve, or even at the peak. Maybe your peak actually drops by 7, but at 7600 rpm, after the hp curve has fallen way off, you get an extra 10. Maybe at 2000 this electric supercharger actually increases airflow and improves hp and torque. Probably at higher rpm it causes a restriction and cuts hp.

Possibly you could retain the benefits and eliminate the drawbacks by fabricating an additional inlet that allows the engine to pull in air from a source not restricted by that blower.

[daveimme]

I don't profess to know the theories myself, but watching the infomercials and their nbrs are quite impressive, but at the same time, I'm quite a skeptic when it comes to this type of stuff.

But it helped....that part is still confusing to me, so be it that he may have 'fixed' it when he dismantled and then put it back together....but the fact that the car feels better is what makes me consider it.

My car runs well, however, I do notice if I let the rpms' drop down between gears...such as coming to a stop, the engine would drop to below 1k rpm, shudder and then come back to its normal idle speed. Why?

It is only irksome when I don't get on the car and run through the gears, but nonetheless, it is a little irritating... seems to me maybe the vacuuming is not right or something. It is not real bad, but it is noticeable...

[char181]

Guess you can't argue with success. By the way, did you get the free set of GINSU knives with this motor marvel?

[Scott R]

Probably just the fact that you removed the air intake boot and installed it again solved your issue. You can get a shudder from improper air flow between the AFM and the throttle plate. Maybe you had a loose clamp.

Good test to prove or disprove this is to remove the "sprial thingy" and see if the shudder comes back.

[bigyagi]

very interesting post, as a few friends have this device fitted to there cars.
most of us,lowly n/a 944 owners, drool over the performance of the turbo version, but very hard to find a pristine model at the right price!.{honest, only used by a little old lady , to go shopping!!}
forgetting the turbo for a moment, it is possible to experiment with a kind of "forced induction". remember those old "smog-pumps" that you will find on the earlier big old cruiser cars? one could be used to blow air into the intake, but very hard to control !
my idea, would be to use a blower motor, but running on a spindle, thru two outer bearings, and running inside a housing. drive can be obtained from the alternator, after you have installed an-other pulley on it. the bearings will be very easy to turn, and so negligible load on the alternator! supercharging, or turbocharging, rely on the extremely close tolerances, between the driven impellors, which collect, and compress the charge. this could be bad for the n/a running with fairly high compression pistons. so using a blower, would only give a "mild" boost, which could be upped, or lowered, by changing the diameter of the slave pulley! not forgetting the "blow-off valve", which is very important. there are options for this.
remember, as af juvat says, you can either increase fuel flow, or air flow.
i might try this, as an experiment, as it will cost me only the cost of obtaining a heater motor, as i can build the housing, fabricate the intake/ outlet, i have the bearings, and can easily make all the required bracketry. i dont see why i should part with around $120 us for a cone filter, which may, or may not, make a noticeable difference.
yes, i'll probably get severely flamed for this reply, but just try and think about it, before you load up the bullets!
the air flow will be increased, all the way thru the rev range, but only with a mild charge, so detonation will not be a problem.
i have been looking at sfr supercharging, and their basic kit, with 5 psi boost, and no engine mods, but $4000 us!! wow!
so, poor mans forced induction, we shall see!
regards, bob.

[AFJuvat]

Actually, that is probably a feasable option, and raises a few interesting possibilities.

You would have to put some sort of metering device inline with the pump though - as air volume/pressure increase, there would have to be some method of increasing fuel flow to avoid over-leaning the engine.

AFJuvat

(PS. bigyagi, how goes the search for a 928?)

[bigyagi]

hi af- juvat! yes, i was just letting my imagination run wild , for a while, but i guess it could be achieved. selecting the correct ratio, between the driven, and idler, would increase air-flow, but only enough, so that the dme would be able to keep things in balance, and maybe also an upgraded fuel pump etc.
dont get me wrong, though, i'm perfectly happy with my car as it is. dont get too many turbo's around here!
as regards the 928, i bought the 944 off my friend, who also owns the 928, and it is totally superb condition, with all maintenance records. its a 1985 model, with only 73,000 miles, but i dont think i can justify it, or at least, i would have to part company with the 944, and thats not going to happen!
he wants #15000 canadian, and i've been told that is really otp, so, i guess i can only dream about getting hold of a pristine turbo someday!
best regards, and thanks for not "flaming" me!!!
bob.

[kenny]

Well, as opposed to some others, I will claim to have a pretty firm grasp of the physics and engineering behind this device.

It may make the air more turbulent; but, there is nothing for free. There is no free lunch here or anywhere else and the US patent office has long ceased accepting patents for perpetual motion machines (except for the cat dipped in a marinara sauce and dropped over a white carpet... but I digress (great story though... maybe I'll post it)).

There is energy lost as the air spins up the 'turbulator' and absolutely NO data anywhere on the site to back up their claims of a whopping 0%! improvement or to suggest the turbulence gained is more beneficial than the energy and velocity lost -- holy whack job Batman. Did any of you actually read the so-called report from the 'Tech' schoo[l]. No data, no before after curves of horsepower, torque, or emissions? If it is so scientific, where is the data?

And the installation drawings look like the were done by 7 year old Billy from Family Circle!!

Even IF this were to provide some nearly imperceptible benefit, these people have no credibility. I posted before (over on Rennlist if you want to look) about a not-to-dissimilar 'electric' turbocharger (which was actually just a fan!). TOTAL SNAKE OIL!!! Those guys had the audacity to have a link to an actual electric supercharger (which was NOTHING like the 'fan') -- which itself was rather marginal but scientifically done with data to back it up at least (this moron was also probably violating the legit guy's patent to-boot!).

AFJuvat was on the money when he said that there are only so many ways to get HP out of the engine -- they are all pretty much known and the laws of physics don't much tolerate being violated (unlike people who send money to charlatans and televangelists)

Caveat emptor!!!