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  #1  
Old 04-10-2001, 12:21 PM
cbsdakota cbsdakota is offline
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Someone said on my Honda post that if I WASN'T concerned with mpg, that I should put on the TB. Do I really loose mpg. I know that the computer has to provide more fuel but is it very noticeable. Anyone out there with a TB and MSD have any figures. I plan to put the TB, manifold, ignition, chip and injectors all in at once. Along with the JBA headers. But I don't want to be doing any worse than 16/20. As much as I drive on base, even with the highway miles I still only average 16mpg on each tank. Can't imagine what it would be with an RT. (very scary because gas costs me around $1.80 a gallon.)
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Old 04-10-2001, 01:45 PM
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QUADDAK QUADDAK is offline
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A TB should not cost you fuel economy. JBA headers will cost you on average about 1 mpg. Combine the TB with a cold air and K&N and you should be a little better. Also, try the Autolites 3923 plugs. You may be surprised.

I have a spread sheet with my fuel mileage computed for every tank I have ever used in my Dakota. I can look back and see how the TB affected mileage if you want, but I am certain about the JBA headers costing you 1 mpg.

I don't know about ignition mods, but I would say that they should not cost you mileage.

I would stay away from the chip, MP computer maybe yes, but that will increase your fuel cost (have to run higher grade) and may reduce mileage a little bit.
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Old 04-10-2001, 02:21 PM
Questions Questions is offline
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Default mpg

i was the one who said somehting about losing mpg's with the tb. The only reason i say this is because my buddy has a '99 r/t with the overhead computer in it (i didnt get that option so i cant really tell when i lose mileage) but he put on a quick d tb and said he was losing on average 1 mpg. but every motor is different and i think alot has to do with the driver's foot.
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Old 04-10-2001, 04:30 PM
DurangoSLT360 DurangoSLT360 is offline
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With my mods TB included I noticed no improvement or no worse off on the highway. It all has to do with your right foot after your mods. After my mods I took a 300 mile round trip and averaged 15.8 at about 70MPH that is what I was getting before. My in town milage dropped .5MPG probably because my work car is 4cyl and when I get behind the V8 I tend to drive it hard just for the fun of it.
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Old 04-11-2001, 02:33 PM
cbsdakota cbsdakota is offline
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I've been told of people who gain a considerable (2-3mpg) with ignition. The cold air kit and TB, little if any. True about the foot. Since I have put on the Flowmaster I ride it a little harder sometimes, for fun. I even popped off a couple revs next to an old 5.0 just to show him how bad his car sounded. He didn't look happy. We have to keep in mind also that all your results are for v8's and mine is a V6 so the results are bound to be less. (or at least proportional) Someone even emailed me and said they got better mpg with the Stage 2 chip. But, with the higher octane fuel price and the likelyhood of more play, mpg will probably stay the same or decrease.
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Old 04-11-2001, 03:11 PM
DurangoSLT360 DurangoSLT360 is offline
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V6 engine build up

test mule was a 92 Dak 3.9 5sp 3.55 gear. 16/21 MPG
added a V8 throttle body (1.625bore to 2.000 bores) had .3 et reduction and little to no change in MPG.

Modded the intake with cut down runners and filled the extra space in the plenum. .1 et reduction and 1.5MPG reduction.

Added super trapp muffler reduced et's .2 and gained back the milage lost to current mods. 16 city 21 hwy.

eventually with chip, tires, and roller rockers et reduced another .8 with no mention to MPG

Each mod done one at a time and an average of 3 runs for each mod.

cbsdakota: I would say go for the modded TB or even a V8 TB. I would think that I not only get docked for having my V8 but if Im horsing around I also have 4WD and 5000LBS worth of Mopar sucking my tank dry. I wouldn't think it would matter much on the six.

My .02 again.
Todd
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Old 04-11-2001, 05:44 PM
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dodgeboy93 dodgeboy93 is offline
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Todd
What kinda times was that v6 turning? I'm trying to decide on my next mod...I want to port an intake manifold ..but If I do a cam and rr's this summer I'm gonna want to do the heads with it. So, I just wanted to find out some of your times with just the intake manifold and rr's.....I'm thinking of going with 1.7 rr's and saying forget the cam.
Thanks
greg
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Old 04-12-2001, 09:30 AM
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2001 Durango R/T 2001 Durango R/T is offline
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What size TB were they using? Is it better to go with a 50mm or 52mm TB? I want to get either an F&B or a Holley. Problem is that I have heard good things about both. Does it matter that I plan to install a Powerdyne supercharger?

I don't understand how the headers could be affecting mileage, as a good set of coated headers will increase scavenging and efficiency (although by putting more stress on the exhaust system with higher temperatures).

As for the chip, it has always been my experience that the fuel economy is inversely proportional to the fun factor associated with any mod.
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Old 04-12-2001, 10:57 AM
DurangoSLT360 DurangoSLT360 is offline
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Default Dodgeboy93

baseline-----------16.6 @ 81
V8 TB---------------16.3 @ 84
Modded intake---16.2 @ 85.5
Muffler-------------16.1 @ 87
Jet chip------------15.7 @ 90
tires----------------15.4 @ 90
1.6 RR--------------15.2 @ 92

These are the numbers in the order that the mods were done. Also the 3.55 gear it had was "open" (smok'n one tire. A limited slip rear probably would also help a lot.

Also I averaged the runs and MPH (in my head) they are appox averages, but the truck was prettly consistant.

I would not recommend the jet chip as all the regulars to the forum know the computer relearns this chip and sets parameters back. I would go Mopar Performance or custom if one is not available from MP, probably would get even more performance from Mopar.

2001 DurangoR/T: The v6 in the article used a stock v8 TB (48MM) I would go with the 52MM TB on your 360 especially if you plan to SC. The 50 MM TB is more for the 5.2 unless the 5.2 is really modded to the hilt then they also benefit from the 52MM as well.

Todd
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  #10  
Old 04-12-2001, 11:13 AM
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DurangoSLT360 - thanks buddy. I was thinking the same thing, but good to know that someone else agrees.
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Old 04-12-2001, 11:39 AM
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Thanks for the info todd. My truck ran a best of a 15.9 at VMP. There was a strong head wind and I didnt get too good traction, I probably could of run a 15.8. My next mods are the fastman tb (installed) k&N 14x3, mopar pcm and autolite 3923's. I hope to be in the mid 15's with these.

greg
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