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  #1  
Old 06-28-2000, 10:28 AM
12vDC 12vDC is offline
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I would imaging that I am like most LH owners. I drive an Vision TSI because it strikes a certain balance: it does many things well. To clarify; I am at the very least a closet enthusiast yet have kids etc. To run errands my wife drives the car too. There are faster cars, more luxurious cars, bigger cars and possibly safer cars, certainly more expensive cars but I don't think there is a car that is everything to all people as much as my LH is to me. I think that what I just said makes some sort of sense. Any how, the relevance of this all is that when I make modifications to my LH, I do so with many considerations in mind. For example, I don't need anybody else who drives the car asking me why there's a switch next to the traction control which turns the 'laughing gas' on and off. In a nutshell; if I wanted to go like stink, I would have bought a faster/lighter car. If I wanted to go like stink, I would not have sold my much missed Talon AWD. This is the context in which I make my modifications and the following is my $0.02.

I still don't understand why Chrysler would go through the trouble of making the 3.5 a OHC engine with 24V and then jam a restrictor into the intake hose. I read much about the existance of the restrictor and still not really believing that it was there went looking for it and to my (naive) surprise there it was. I pulled it out with great zest and took the car for a drive. I expected the car to sound "throaty" as everyone said but only found that the car was slightly less wheezy at high rpm. I further examined the airbox and noted that the intake snorkel running through the inner fender wall looked restrictive with a narrowing that was approximately 3/4 x 4 inches. I haven't done the math but this snorkel was probably as restrictive as the intake restrictor that I pulled out so this snorkel came out too. Again with great zest. I figured that a 3 in. hose, even if it is corrugated and with a few bends, can move considerable air. Certainly more air than could make it through the airbox. I then took out the airbox and drilled twenty or so 1/2 in. holes in the bottom of the airbox leaving enough of the original bottom to deflect leaves and similarily large debree. This time, when I took the car for a drive it definitely sounded different ... perhaps "throaty" above 3000rpm depending on throttle position. My "by the seat of my pants" assessment was that I had increased the mid to high rpm horsepower though probably not the low end torque.

This of course brings me to the next obvious question. Do I go down to Lordco or Canadian Tire (yes I live north of the 49th) an pick up a K&N FilterCharger? Having read as much as possible, I could not find any data supporting claims of increased horsepower and a faster car. I imagine that if I drove my car for 50K without changing the filter, I probably would do better with a K&N. I was not certain that a K&N would give me a mearsurable difference over a new paper filter though. Here, north of the 49th, using our Canadian currency, a K&N for the LH will set you back $90 ... a paperfilter for the same application is $5. You can see where I am going. In addition, I and several others had doubts that a K&N FilterCharger filtered as well as a paperfilter. Others have suggested that a K&N lets through a certain amount of debree and a friend using a K&N in his SHO comfirms this. The inside of his airbox downwind of the filter is coated with what he calls 'vegetable oil' and stuck to this is what he calls 'crap'. His hope is that through some sort of vortex/cyclonic action most of the debree that makes it through the K&N is flung against the vegetable oil and sticks there. Maybe it is and maybe it isn't. Who knows?? He thinks that the K&N gives him a performance boost. He estimates it to be 'approximately 3/4' of what he would have if he was running without any filter. As for me, I'll be dropping by the auto supply store every six months and dropping $5.

The arguement that using a permant filter is better for the environment than continually replacing your paper filter doesn't wash with me. Lets face it, I am not doing the environment any favours by driving my car regardless of what kind of filter I have installed.

Next up is consideration of the exhaust. There is no shortage of claims that going with a dual exhaust, cat back system or removing that large resonator liberates more than just a few latent ponies. I for one, am not yet convinced that replacing a substantial amount of the factory exhaust will make me quicker. I don't think that there are many latent ponies to be liberated. I have no doubts that modifying the exhaust will make me louder and if that was all I wanted then I could save myself alot of money and just punch some nail holes in my muffler . Nobody has yet told me that I will make it to 60mph or the end of the 1/4 a certain amount faster. No doubt that it will seem faster; to my ears at least. I, like many, have driven around in a car (not my LH) which has had the muffler fall off. In the few days of driving before the exhaust is repaired the car is loud as anything but having dropped the backpressure the car has a noticable loss of low to mid range torque/horsepower. The stock cylinder pressure when the piston reaches TDC assumes that there is a certain amount of unvented exhaust gas still in the cylinder when the exhaust valve shuts. If too much exhaust gas is vented (ie. no backpressure) there will be a drop in the achieved cylinder pressure at TDC and a corresponding drop in output. The compression ratio, valve timing, ignition timing, grade of gas recommended etc. all are set assuming that a certain amount of exhaust gas will remain in the cylinder. Change this amount of exhaust gas too much and you'll need to change something else. Perhaps increase the compression ratio or jam more air/fuel mixture in there (porting/changing throttle bodies/forced induction of some sort). Sound expensive?? So unless somebody tells me that I can expect to take 0.5s off my ET, I am not going to be taking my LH with its' intact exhaust system down to the muffler shop. Now, if my muffler just happens to fall off ... well, that's another story.

Other modifications? I am considering Eibach springs. The local Dodge dealer here will do it, including an alignment, for $400 of our Canadian loonies. I think that that is about $240 US. Somebody correct me if I'm off on the conversion. Anyhow, that's quite a bit less than the $500 US amount mentioned by some. Maybe I'll put in a plug for Columbia Dodge at this point. Located in New Westminster, British Columbia. Bring your Eibach springs and support my Dodge dealer . Other modifications in the running? How about a polyurethane bushing kit and perhaps brakes. No body talks about brakes. Brembo doesn't make anything for the LH. This is a big car and I wouldn't mind if I had help slowing it down. You know, so that I don't run over the tricycle in the driveway. Cheers.

[This message has been edited by 12vDC (edited June 28, 2000).]
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  #2  
Old 06-28-2000, 03:28 PM
GR8WHT GR8WHT is offline
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I have a 3.5 LH, are you refering to past generation 3.5. I have a new 3.5l , where is this "Restrictor" in the intake you are refering to?

Thanks
Steve
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  #3  
Old 07-01-2000, 05:35 AM
12vDC 12vDC is offline
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Yes, I am referring to the past generation 3.5 litre. The Eagle nameplate was discontinued and the new LH is only badged as a Chrysler or Dodge.

Has any one considered moving the battery to the trunk and using the freed up room for a second airbox or airfilter element? This would also help the balance of the car though I do not know if the difference would be noticable.

Another thought on the question of exhaust modifications: perhaps a pressure actuated pop-off valve between the catalytic converter and the resonator would work. It would give the 3.5 the needed backpressure at low rpm but open at a certain point. The valve could be vented directly to a diffuser of some sort or (if you can picture this) a side pipe venting in front of the rear wheel on the driver side. The valve could also be connected to a length of 2.5in. pipe which would hook up with the post-resonator section effectively by-passing the resonator but still sending exhaust through the muffler. If I recall correctly, the Stealth/3000GT has a valve of some description in it's exhaust system. The valve was to open at some pressure and I thought that it could also be openned from the driver seat via a switch. If this is the case, it would almost be too easy if the valve worked with a 2.5in system.

Any thoughts on this?
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  #4  
Old 07-01-2000, 07:55 AM
brun064 brun064 is offline
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I thought of the exact same idea of running dual air intakes but soon scraped it because the ABS stuff was in the way and it seemed easier to redo the current one with a larger diameter pipe. Right now I'm working on a under car ram air system. I cut the bottom of my airbox out and put in gutter screening and I'm trying to find a way to make a kinda scoop under the air box.....looks like I'll be at Home Depot alot this summer. Just wondering do you know the difference between the Vision ESi and TSi?
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  #5  
Old 07-01-2000, 06:05 PM
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Fluid Fluid is offline
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12vDC: I 'believe' that the exhaust pressure relief valve you mean on the 3000GT is the waste gate on the turbo - at a certain boost value it opens to vent excess air going to the engine. But the idea about a pressure-sensing "valve" in the exhaust sounds very interesting...a good idea if it could be made to work, giving the best of 'both' worlds.

Your comments about why the intake restrictor, etc. - it is likely at least partially due to a lack of inter-discipline pre-planning. The engine group designs the best engine they can given the imposed cost limits, then the engine is built and put into a 'test' vehicle. The acoustics engineers find that the interior noise is too loud to meet the prescribed limits, so they search for ways to reduce it and....voila, the intake restrictor! Building cars is a series of compromises, with cost and buyer acceptance the bottom line.
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  #6  
Old 07-02-2000, 03:56 AM
12vDC 12vDC is offline
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Fluid, thank you for your insight into R&D. With regard to the pressure actuated valve, I believe that the Stealth had a valve on the exhaust side which could redirect exhaust flow. This was in addition to a wastegate on the induction side which as you stated was intented to vent boost pressure at a preset level. After the holidays, I will verify that such a exhaust valve exist in the Stealth.

Brun064, the TSI was to the old LH's what the 300M is to the new LH line. The TSI was positioned as the high performance 'euro-killer'. It came fairly well equipped but most importantly it had the 3.5 (still rated at 214 hp though), performance suspension, Michelin XGT V4's, and no speed limiter. I can vouch for the absence of a speed limiter and for the effectiveness of the performance suspension. It was a suspension which a few automotive journalist thought was to 'harsh' but I for one do not agree. The ESI to my recollection, unless specified with options, was equipped with the 3.3, 205 tires on 15 in. wheels, and touring suspension. The base suspension was dropped after 1993. In later years the TSI and ESI were both burdened with the added weight of body clad moulding.
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  #7  
Old 07-02-2000, 06:22 AM
brun064 brun064 is offline
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Speeking of the speed govenor, do you know where it is located. I know it is activated in the PCM, but does is cut of the fuel, air, ignition? I think it might come from a 1/2 inch vaccum hose attached to the air intake plenum on the drivers side. My Hane's manual says this is related to the "speed control vaccum pump" I don't know if this is the cruise control or the govenor. Any help would be much appreciated.
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  #8  
Old 07-04-2000, 07:11 AM
12vDC 12vDC is offline
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As we all have heard, the speed limiter is there to keep us from overcooking our tires and leaving the road while littering the tarmac with hot molten rubber and glowing steel belts. I have often wondered what is defined as a "sustained speed". For what duration, how far over the rated limit, at what ambient temperature would I have to drive to be at risk for tire failure. I doubt that most of us could find enough open road to induce tire failure. Imposing speed limiters seems more for keeping the corporate lawyers happy than for protecting us from ourselves. Again, I would be interested to know what defines "sustained speed". Knowing that, I think that I should be able to decide what speed is safe for how long.

As for your question regarding the limiter. I have heard of people trying to override this by chipping their vehicle or finding a PCM from a junked LH which had the high performance suspension and wheels/tires. Chipping the LH seems to necessitate removing the PCM (located in the footwell)and sending it out for a cost of $300 to $400. Apparently, for the dealer to do this they will need to know where the PCM came from and would not override the limiter in a vehicle which had one from the factory. As for finding an appropriate junked LH, this would likely require checking VIN numbers. I checked my TSi and it too has the 0.5in. hose running into the driver side of the plenum. I suspect that this has to do with the cruise control. If the cruise control were to malfunction (i.e. blown fuse) I do not know what might happen to the limiter.

[This message has been edited by 12vDC (edited July 04, 2000).]
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Old 07-04-2000, 01:24 PM
GR8WHT GR8WHT is offline
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Speed limiter, Am I missing something. The pcm reads the speed sensor, and thats all it uses for the speed limiter. PCM reaches a set level and thats that. On performance ones its just set higher or deleted from the program.

Side note, I know this is about previous gen LH's, but on the new ones, PCM reads from the body computer what model it is so if you try to reprogram the pcm, it will not allow it, only the program for that model will be allowed. Trust me I tried, I have a 2000 Intrepid R/T, when they hook up the computer to the car, the first thing that happens is it reads the model from the pcm via the body computer and lists only the programs for that model. Too bad, I wanted to put the 300M program in to get the 10 HP back, but the computer will not allow it.
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Old 07-04-2000, 07:30 PM
brun064 brun064 is offline
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The PCM only reads the speed and cuts off a certain important part of the engine. Whether it be air, fuel, ignition, etc. For instance my friends '95 grand cherokee had a speed limiter in the PCM, but the PCM activated a valve that closed off air going into the engine. All he had to do was cut one wire and he can top out at 130 mph now. As for the 1/2" hose, i think that is the power brake booster, when i unplugged it my engine wouldn't even turn over. I think the speed control right under it (its about a 1/4" hose) but i doubt that small hose could limit the speed like that. But just incase, does your TSI have a smaller hose under the larger one?
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  #11  
Old 07-05-2000, 02:43 AM
stanz510 stanz510 is offline
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being a technician and working with mother mopars finest, i can tell you the speed limiter works by cutting fuel on MOST chrysler vehicles. jeeps use a different version of a pcm called a jtec as opposed to the LH smec. the stealth and 3000gt have a dual mode muffler, by flipping a switch on the dash, the driver can control the exhaust path through the muffler one is a 'sport' and the other is a cruise setting. they are expen$ive. a broken cruise control vaccum port will not affect the speed limiter, but will hurt performance (vaccuum leak)
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Old 07-05-2000, 08:44 AM
brun064 brun064 is offline
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Does the PCM send a signal to cut off the fuel. In other words can i cut a certain wire and remove the limiter or is it built into the fuel "program" and regulate it through the normal control wires. I'm just throwin' out some questions if they make no sense just ignore them. Thanks.
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Old 07-05-2000, 09:24 AM
12vDC 12vDC is offline
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Brun046: I have not checked to see if I have a smaller hose under the 0.5 in. hose but I will. I'll let you know.

Stanz510: You were certainly right in that the dual mode exhaust is expensive. Checking into the Mopar manual and catalogue there is an exhaust muffler control referred to as an 'actuator'. The schematics for the Stealth R/T (awd/turbo) shows that the exhaust is a single exhaust for the most part. Just before the centre section of pipe joins the muffler it hooks up to the actuator. It is the actuator which then joins the muffler. The actuator also has another exit on it which will direct exhaust flow to what appears to be a small resonator and ultimately to a twin tip diffuser. The muffler has its own twin tip diffuser. This actuator will allow exhaust to bypass the muffler once a certain pressure is reached but it can also be activated via a cable from the driver seat. Cost for the actuator alone is $695 (Canadian). A system such as this should allow sufficient back pressure at low RPM but give better flow at high RPM ... but the cost !! If anyone out there would like to give this a try the actuator is part number is MB810 722. I am going to have to contemplate this a while ... but I am not ruling it out.

[This message has been edited by 12vDC (edited July 05, 2000).]
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Old 07-18-2000, 06:52 AM
12vDC 12vDC is offline
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Brun046: no smaller hose found under the 1/2in. hose on the plenum in my TSi.

While we are on the topic of plenums and intakes: What does the manifold tuning valve (MTV) do? Is it responsible for switching between the long and short runners?

I have found that Energy Suspension does not make bushings for the LH's. Does any one know of a producer which does? I am most interest in a polyurethane bushing kit for the rear sway bar. I would like get rid of some of the understeer. It seems that being on and off the throttle through a corner only allows you to determine how much understeer there is. I would like to be able to have the front end tuck in a bit if I take my foot off the gas in a turn. I think that a relatively simple and inexpensive way of doing this would be to try polyurethane bushings in the rear.
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  #15  
Old 08-05-2000, 02:43 AM
12vDC 12vDC is offline
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I took my 95 LH 3.5l through 'AirCare' today without the intake restrictor and the airbox openned up as described. I did not think that the modifications would effect the emmisions and I was pleased to see that this was the case. The test checked the vehicle at idle and while driving on the dyno. The test results of today compared favorably with the results from last year.
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