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Dakota Performance
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Biff
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4/16/2001
11:35:40

Subject: 2001 catback exhaust & y-pipe question
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Hello,
I understand that historically, chrysler exhaust systems were pretty restrictive. According to Gibson's web site, their catback exhaust system would yield +20hp and +30ft-lbs on a 5.2 engine.

However, the 2001 4.7 engines now have catalytic converters that reduced HP by 5 from 2000 to 2001. With such a big restriction ahead of the catback exhaust in the 2001 model, will putting on a performance catback exhaust system really do much of anything?

P.S. I called Gibson. They said their catback exhaust system would increase HP +9 and torque by +16 on the 2001 dakotas. (These numbers are about half of what the results were on the 5.2, maybe due to the more restrictive cat setup?) Just curious if anyone else has experience to back up Gibson's claims and/or your thoughts.

P.P.S. Finally, I've heard the y-pipe is dinky. Has anybody replaced this with a bigger pipe. People on the Audi A4 sites have replaced the "downpipe" on the 1.8 turbo engine and seen +15 HP improvements. Again, curious on your experiences and/or thoughts.

Thanks in advance,

2001 Sport Quad Cab 4.7l w/ K&N Drop-in 3.55 LSD Auto







RonW
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4/16/2001
11:44:22

RE: 2001 catback exhaust & y-pipe question
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Your problem on the 4.7's are the pre-cats. The whole exhaust manifold, header, Y-pipe thing needs to be re-thought and redone. People are working on it but I haven't seen a real solid resolution yet. Since Mopar is not considering anything at this time, even the aftermarket manufacturers have quietly dropped their testing and prototyping or at least slowed it way down.

On the positive side (if you can call this positive) your cat back is still restrictive and a custom cat back would be helpful. Gibson's numbers are probably the best you could get, all else being optimal.

On another note, you should be concerned about the breathing from the intake standpoint as well. K&N will have a FIPK out for your engine this summer. Flometrics.com should have a custom billet TB for your engine as well. Then the cat back really becomes a necessity. Remember, when I said all other things being optimal. Well, intake and TB are definitely complementary items to that cat back.

Ron
00 PB SLT QC 4X2 5.9 46RE 3.92 LSD

MACE
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4/16/2001
13:12:17

RE: 2001 catback exhaust & y-pipe question
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To Ron W:

Is it worth waiting for K&Ns 4.7L FIPK (it doesn't replace the box hat, right) or is AirRaids cold-air induction system with the heat shield, a good choice in place of the K&N FIPK?

For all, thoughts on the Magnaflow cat-back system -vs- Gibson (at least for the 5.2/5.9, as I believe they don't offer one yet for the 4.7)

I spoke to a Gibson tech and got slightly better numbers for their 4.7L single side swept cat-back exhaust (they say this is the best for gains, out of the 4 systems)...he quoted 12HP, 25ft/lbs torque of 'usable' gain...with me thinking of the rpm range where the gains are there...would the Magnaflow gains also be in a usable rmp range?

And, thoughts on 'performance' cats, believe Magnaflow offers these as well. (BTW, are there two inline cats on the 2001 4.7?)

With the above, and once a reliable PCM or chip upgrade comes out for the 2001 4.7L, we can indeed wake up and tweak the 4.7 a bit more without going under the covers...



jsatter
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4/16/2001
13:31:36

RE: 2001 catback exhaust & y-pipe question
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I went ahead with the Airaid intake for now. I knew that what ever I bought would just get replaced by the K&N once it's released so I just went with the Airaid because it was cheaper then the rest. $140. Once the K&N comes out I'll either E-bay the Airaid or try to modify it for my wife's Sportage.

01 Quad Cab SLT Plus 2WD Auto 4.7L - Currently Stock

RonW
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4/16/2001
14:23:13

RE: 2001 catback exhaust & y-pipe question
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On the 5.9's, K&N replaced the airhat as well as the rest of it all the way to and including the filter. The airhat's a pretty restrictive piece on the 5.9's and the K&N helped a lot. The airhat and the tube is plastic and doesn't conduct heat like the AirAid. Hopefully, K&N will do the 4.7 justice as well.

As for the cats, I thought there were three on the 2001's. As far as changing cats, it's against the law for anyone to change out cats until 80K miles except for the dealer and they can only do it if the cat goes bad. That's federal law. Again, the numbers that a manufacturer gives you are optimum numbers under optimal conditions.

Ron
00 PB SLT QC 4X2 5.9 46RE 3.92 LSD

Biff
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4/16/2001
16:33:21

RE: 2001 catback exhaust & y-pipe question
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Hello again,

Ron/Mace ... I believe you are correct about replacing the cats being illegal. In addition, several people have stated on these boards that the cats they put on the factory are "high-flow". I've read people have increased the size of the tubing going into and out of the cats, but not changed the cats.

Ron ... I'm eagerly awaiting the FIPK this summer. If it is a smooth straight shot to the throttle body, and others here vouch for the improvement, I will probably purchase it.

I'm not so sure I will buy the TB though. My understanding is that the 2001 dakota's TB was bumped from 65mm to 68mm. I believe somebody on the MoparChat Dakota forum dyno tested the difference between these two TBs and gained about 4-5 HP. I'm not sure about the TQ? Anyways according to a post on this sight the numbers based on the F&B vs. 65mm TB gained about 5 HP. So (in theory) a HP gain would be minimal between F&B and the 2001 68mm TB. However the torque was significantly higher with the F&B TB vs. the 65mm. They also stated the power curve was still increasing when the vehicle shifted into the next gear. This was not true of the 68mm TB. Of course, they always say TQ is what increases acceleration. Maybe we need to get hypertec to come out with one of those control modules that adjust the transmission's shift points? Anyways, as you tell above, I'm just not sure how effective a TB will be on my auto truck.

Finally...Mace... It's interested you were quoted different numbers than I. I did not specify what type of exhaust I was looking at getting. Maybe this would account for the HP difference, but the TQ numbers were quite different! I'd sure like to seem a third party's dyno test on a 2001.

Thanks again Ron & Mace on your contributions. I refuse to spend any money until I'm sure of what I'm getting.

2001 Sport Quad Cab 4.7l w/ K&N Drop-in 3.55 LSD Auto











MACE
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4/16/2001
17:06:52

RE: 2001 catback exhaust & y-pipe question
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Spent some more time on the NET and on the phone today, so I don't spend more 'money' on something that I could buy cheaper and get more HP/TQ gains.

I called the tech line at Magnaflow...the 4.7L cat-back system will be out in June...3in setup, single pipe and tip, $490 for stainless steel.

The tech was very slow to quote the gains: 10HP and 20TQ (I actually said the Gibson system offers 25 in TQ, what did his offer, 20-25? He said; 'Yah, something like 20'

I think I just scratched Magnaflow off my list...

BTW, advertising hype or does Royal Purple Synthetic Oil really provide the HP/TQ gains they claim? A few 'pro' racers have testimonials on their web site: http://www.synerlec.com/

Anyhow, think when it comes to the exhaust for the 4.7, I'm just gonna do a Gibson cat-back upgrade.

May splurge on Airaid's cold-air induction system till the K&N GEN II comes out, as for a PCM upgrade, will have to wait and see for 2001, at least 1 PCM (stock) reset will be in order after installing the cat-back and cold-air systems.

Thanks.



MACE
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4/16/2001
17:59:27

RE: 2001 catback exhaust & y-pipe question
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Biff:

When I called the Gibson tech line, I first asked which of their 4 cat-back systems offered the most HP/TQ gains, regardless of noise in the cab or price...he said the Swept Side system is their ultimate power producing system, and also the quietest, re: noise in the cab.

I then put him on the spot and asked what are the real world usable gains, and he said 12HP and 25 FT/LBS of torque...perhaps I just reached a agressive tech who was a salesman in a past life, compared to the tech you spoke to?

At the moment, Gibson looks like the way to go for me (my 2001 AWD/Auto/4.7/3.92/LSD is in transit from the factory)



kota on 20s
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4/16/2001
18:44:34

RE: 2001 catback exhaust & y-pipe question
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20 HP on a 5.2 with a gibson?!! I have the gibson cat back, and I hardly noticed a differance...maby 5 HP!! my intake, and throttle body made much more power than the exhaust.

mopar muscle did a intake and exhaust on a 99 R/T, the intake gave it 9 HP and the exhaust LOST 1 HP, and gained 1 footpound of torque.

Eric 98 on 20s



aggie97
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4/21/2001
18:07:54

RE: 2001 catback exhaust & y-pipe question
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Well, I just ordered the split rear gibson for me 00' QC 5.9. Should have it by the end of the week and I will let you know what I think. Kota, as for the R/T testing, you might be right. I drove two new R/T's when I bought mine back in 99 and they had distinctly different levels of power. One ran worse than my old 94 5.2 with no mods and the other....the one I took home, ran twice as good as the other. I also remember C Van Tune form Motortrend writing that he was surprised he could not break the tires loose on the R/T he test drove for the Mag. Well, I know my rear tires were bald, no definable tread at all in 2500 miles!!!! I could not keep them from spinning. There may have been some bad R/T's or they just weren't broken in yet. Mine did not start really running well until about 10k miles on it.

Also, in reference to the y pipe. I posted a question a while back about the restriction in the y pipe and was told that it helped torque.... well, if reducing restriction in the catback helps, why does it not at the y pipe which is further up the chain?

Ultimately, I don't plan to make any electronics changes unless necessary. I am planning on the bigger TB, mike leach headers, crower rockers 1.7's, and the Gibson that is on the way. This should be good for some power and mileage as well as a good exhaust note. I am hoping that by getting that much more air into the engine, I don't start running lean. In my experience with Mustangs, which are mass air systems, more air equalled lean burn which has been backed up in several magazines. Maybe the Dodge fuel system is a little better. Just read the Motortrend article about the new hennesy viper and it said the factory fuel and engine mgmt/timing system was good for up to 700hp. That is about a 40% increase so it sounds like they are flexible.

Great posts by all and I am going to keep reading and getting smarter.

2000 QC 4x4 5.9 Black, no mods.....yet!!

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