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Discussion Starter #1
anyone have the build sheets on any aftermarket header set made for the plymouth prowler? i would like to see if a set could fit directly to the intrepid's 3.5 without making (major) modifications to the block. thanks!
(oh yeah, and clearance within the engine compartment) :rolleyes:
 

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I was told that the prower headers won't fit our cars....whether they won't fit the exhaust manifolds or inside the actualy engine compartment, I am not sure....again, this is only what I was told......but go ahead and try! I heard they add 5-10 HP or so to the Prowler...
(not as much as other cars would get because we have pretty decent headers on the 'treps anyays...
 

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with the way our headers are set up why can't we run true duals?

why not cut the pipes off before the cats, get 2 HIGH flow cats, one for each pipe, then run them straight out the back? yes, this is illegal but if you have the cutting and welding equipment it would be a fairly straightforward job, wouldn't it?
 

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I wanna do that.. but I got the O2 sensors before and after the primary Cats. if I put high flow cats on, the O2 sensors would be outta whack, because the cats probably would work better. :p
Also, I am having a money issue... so, maybe in a few years or so.
 

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Discussion Starter #5
problem is, there are 3 catalytic converts, and in some states it is quite illegal to remove any one of them unless it is needed to be replaced. (but im sure the car can run clean enough to pass inspection with the two header cats...they never checked under the car during both of my inspections)...plus, the diameter of the piping in the headers is smaller than the regular dia. of the pipe...so the duals would be smaller than 2.5"....NAH FORGET THAT...im gonna run duals but the diameter of the pipes is gonnna be 4"

:mad: :mad: :mad: :mad: ...kill....KILLLL!!!!!! mwahahaha!
 

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FOUR INCHES!?! Are you crazy man? You'll have absolutley no back pressure, which in turn will give you absolutley no low end torque. It would be worse than those high winding Honda engines with 240hp and 153lb ft! (S2000)

****, even guys with insane turbo setups on thier cars harldy ever go larger than 3".

[ October 04, 2001: Message edited by: LHSer ]
 

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Discussion Starter #7
sarcasm.....i was only kidding. :p i didnt think i sounded serious...hmmm...maybe that kill kill thing was a little over the line, huh? :D i believe i am gonna trash the whole thing and start scrounging for a short-block chevy crate motor for the olds...
 

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hmm.... for some reason, this whole back-pressure/lower torque thing doesn't make sense to me. I look at the Funny cars and stock cars, A Pipe per Piston, 2 inches long, right out of the hood.. shootin fire... ZERO back pressure... yet it still does a wheelie and tears down the track. ya think if the backpressure would help torque, he would have some Cat's and OEM Honda Civic Mufflers on that bad boy... REALLY get the tires spinnin.
If anyone has some info that can I can read or something, it would be much appreciated.
 

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correct me if I'm wrong but those things have like 7,000 horses under the hood, I wouldn't think that low back pressure would make much of a difference with such power like that...
 

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I dunno.. I was just using an example that seemed obviously against the theory... I just want to know about it. :p
 

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Ok on the subject of backpressure. Backpressure increases low end torque while hindering your high end horsepower. The lower the backpressure the lower the torque. It doesn't mean that you will have NO low end torque.

In the case of dragsters, you aren't really talking about low end torque. When they launch, they are typically launching around 4000-6000 rpm. In that case you are just throwing all of the momentum of the engine at the rear wheels. Their low end torque is nothing like what you would want it to be if the car were a street car meant to be held at rpm's around 2000-4000. Drag cars are also working with 600+ hp & in most cases over 1000 horsepower.

I don't know how the decrease in backpressure will effect our 'Treps so I can't say whether or not what Valhalla 21340 is saying will actually hurt or benefit the car. I will say that 4" is WAY too big for even a 350cid Chevy, unless you are running it at rpm's reaching into the 10000 range. For our 3.5L engines I would say that 2.5 per side would almost be too much. What you should look at is the size of the exhaust ports where they exit the heads, measure the cross-sectional area & size your pipes according to 3 times the cross-sectional area you found. This should be a pretty close approximation to the optimized size.

If the pipes are too large the gases will expand in the pipes and actually slow down instead of speeding up. This could cause problems with hot spots in the exhaust system and make it wear out faster.

Ah and another thing, I would really like to see how you are going to fit 1 4" diameter tube under there, let alone 2.
 

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hehe.. I guess I am just exaggerating too much today. I am just curious on the backpressure thing. Its funny you mention the 4" pipe on the 350 chevy thing. Our conversion Van, (350 Chevy) Got a 4" pipe installed when the 3.5" rusted out. Didn't lose any power really.. still can break a tire loose from a stop (one wheel wonder) and it gained about 2 mpg (16 hwy to 18 hwy) That is why I am just in question about the back pressure thing. Maybe it is just a Case by Case thing?
 

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Discussion Starter #13
i shouldnt even have mentioned the word 4 inch pipes...i was oNLY kidding around, wasnt meaunt to be taken seriously. and about the 2.5" duals idea, read one of my other posts concerning the installation of such a modification. i most likely aint gonna run em that big, (the only reason i would is to save myself from buying another 40 series flowmaster...the one i have on it now is 2.5")
not to sound like a jerk, (i actually like these discussions) but the whole backpressure thing seems a little redundant. when i first started posting this site under my 1st name, before this site had a makeover (i fn forgot my name, but i was there...i remember talking to brun064...theres a post on his website from me about my current exhaust: crazycooter)
i mentioned what i was doing, some other people did the same mod b4 (just cutting out the resonator)...people were talking about backpressure...when i completed the job w/a flowmaster, i noticed a healthier kick throught the car's speed ability, my 1/4 mile time dropped considerably (from a best of 15.734 @ 93mph to an <extreme> best of 15.283 @ 94mph; it may have been more weather and better reaction than mechanical performance gains, thou) but the mention of the word backpressure, and the way people were talking about it made it seem like the car would be a total slug (moreso than it already is :p ) anyway, just wanted to bring that one up........(lemmie try the joke thing again) when i work on my oldsmobile, its gonna have 6" pipes that extend 10' from the rear bumper to HUGE chrome tips...hehe that was funny...(no it wasnt, dave you suck ass)
 

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Well there was the time I had an '86 Hyundai Excel and the whole exhaust from manifold back fell off. Thing sounded like a John Deere tractor on crack...but it did seem to have more kick. :)
 

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how the hell are you running a 15.3???
 

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Discussion Starter #16
the 15.2 was a misprint, it was a 15.383.
someone before asked me this: i did some pretty crappy (temporary) modifications to the vehicle. with the thermostat i have in it now, i let the car cool down to just barely regestering on the temp gauge. opened the hood a crack, removed the passenger side turn signal, ran a hose directly through the fender from the signal port and directly onto the intake hose (minus the air filter, i dont recommend doing this...i also placed a section of thin sponge/cotton material in the hose to catch anything), had barely enough gas to make it home, took out everything (spare tire, jack, anything heavy), pumped the tires to 36 psi; car was just aligned and balanced, (crap i need to find a scanner so i can post the printout from the track, nobody believes me) hey, i think it was you who asked me a little while ago how i ran this quick.
anyway, i brake torqued it to 2000k or so, and just as the last yellow changed i planted it...used the autostick (not that it made a difference) rode 1st to just 4f redline, shifted, rode 2nd to 5500k shifted to 3rd, and waited to cross the line. car ran straight as an arrow,...
i also took out the accessory belt leading to the A/C compressor (not that it did anything, the compressor spindle was squealing something fierce)
i dont know,...ill try this again sometime, i just dont have the time right now. want to see if i do this again the same way,,,maybe itll be consistent, but i doubt it.
 

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good damn time.
 

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Discussion Starter #18
thanks, man. thats the tradeoff...the only way i could pull 33 mpg is if i park my car and steal a honda
:D :D :D (just kidding...aint even worth stealing, and i wouldnt be caught dead driving a lawnmower on the street)
 

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you might pull 33 if you kept that temporary mods done for a highway trip. of course with that air intake your engine might not be running 500 miles down the road. :D
 
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