They weren't going to go to a 52 as that would of meant re-doing all the intakes to match. That's a lot of production money spent in re-tooling, design and recasting.
They weren't going to go to a 52 as that would of meant re-doing all the intakes to match. That's a lot of production money spent in re-tooling, design and recasting.
Not necessarily. If the mods make more power, and increase the efficiency of the motor, then you can see an increase in mpg's. I did on my Scamp. When I rebuilt the engine on my Scamp, I ported the head, installed a bigger cam, bumped the compression, and installed headers and a free-flow exhaust, and I instantly gain 4-6 mpg, depending on how I drove it. Best previous mpg was 27, afterwards, I regularly hit 33... This wasn't a worn out engine either. It only had 75K on it when I tore it down.
Of course, all this is highly dependent on your performance goals. Taking a stock TII, and modding it to make 400 hp, sure, you will hurt fuel economy. But for folks interested in making just a little more to make a fun street car, you can have both.
There is one absolute law for fuel mileage: Your mileage is always inversely proportional to the pressure applied by your right foot.
That is also the beauty of turbo engines, you can make them stupid powerful but sip gas when not going all out.
1989 FWD Turbo Caravan-2.5 TIII, GT35R, auto, a/c, cruise, pwr windows/locks, fully loaded with interior and ran with full exhaust. RETIRED FOR A FEW YEARS! 12.57@104 :O)
1984 Chev Getaway van, 6.2 Diesel with a remote mounted turbo setup burning WMO-For sale.
2003 GSW 2.0L TDI, auto, fully loaded, modified, 360K-wife's.
2004 GSW TDI, 5 speed, fully loaded, modified.
Aurora ignition wires for sale. Link to info
Super60 roller cams or custom/billet cams. Link to info
they probably didn't spend so much as not to save it back again in the first year or so of only produceing one casting
and one look at the one piece says they were not concerned with haveing an intake that makes more than 175 hp so there's no need tor the 46/52 mm swap
Mike Marra
1986 Plymouth Horizon GLMF "The Contraption" < entertaining sponsorship offers
Project Log:
http://www.turbo-mopar.com/forums/showthread.php?69708-The-Contraption-2013-14&highlight=
1) It would have cost nothing to introduce the 52 mm TB on the 1-piece in 1988 as the intake was a new piece already, it would have been a simple matter of designing the intake for the 52 mm TB right out of the box which was already in production on the 87 3.0 minivans.
2) They were very concerned about the design of the 1-piece intake, have you read the SAE paper on the 2.5 Turbo I engine package? It is discussed in some detail.
The one piece was introduced to further reduce the number of parts in the package (cost savings!) which buttresses my position that there was another reason for retaining the smaller throttle body. Chrysler accountants despised redundant parts and went out of their way to pare back parts complexity and packages to save money. Hell the 2.2 engines ended up with small block mopar spark plugs in an effort to reduce part numbers! RN12YC wasn't the first choice.
If they could have pitched the 46mm and reduced parts in the parts bin they would have. Either there was a drivabilty issue or an emissions issue at play.
Working on clearing the decks.
I don't think the first 3.0L engines came with a 52 mm throttle body. My last trip to the junk yard found a smaller one installed on a very stock looking 87-90 engine.
On topic, I never was looking for MPG's with my shadow, but I can see how your point (mopar-tech) because I haven't looked into the SMEC side of the program.as well as seeing it as a moot point on my mega squirt experience as Manifold pressure was the primary input for fueling calculations and TPS used more as a "fuel enrichment" calculation. Either way, if that's what you found, cool.
I haven't noticed any changes in MPG when I put the 58mm TB on my R/T, still 24 in town 30-32 hwy. The only noticeable difference it made is that at lower engine speeds the throttle can feel soggy depending on how far the loud pedal is pressed down. I remember 5didgits explaining the how&why of that. It boils down that the engine is ingesting all the air it physically can at the lower RPM at a given throttle opening, so opening the throttle up more doesn't make any difference since the engine can't take in any more air.
I can see how that effect could cause a slightly lower MPG depending on driving habits. Engine doesn't feel responsive to throttle input, so you give it more and more throttle until you're in boost and then you sharply back off the throttle. I've caught myself doing that countless times. Even though the engine is making essentially the same amount of power out of boost, the smaller TB gives the feeling of more responsiveness so you're less likely to be as heavy footed. The second thing that would have an effect, albeit very minor, is the additional fuel used to mimic the accelerator pump shot when opening the throttle more due to the unresponsive feeling.
If the people of the nation understood our banking and monetary system, I believe there would be a revolution before tomorrow morning. -Henry Ford
True dat, same issue with diesels right now, they are plugged up with emissions at the expense of MPG.
If the 52mm t/b was already around, wonder why they made a 46mm version? That surely added costs.
1989 FWD Turbo Caravan-2.5 TIII, GT35R, auto, a/c, cruise, pwr windows/locks, fully loaded with interior and ran with full exhaust. RETIRED FOR A FEW YEARS! 12.57@104 :O)
1984 Chev Getaway van, 6.2 Diesel with a remote mounted turbo setup burning WMO-For sale.
2003 GSW 2.0L TDI, auto, fully loaded, modified, 360K-wife's.
2004 GSW TDI, 5 speed, fully loaded, modified.
Aurora ignition wires for sale. Link to info
Super60 roller cams or custom/billet cams. Link to info
So botched it required two paragraphs of detailed information in the 2.5 Turbocharged SAE paper #900852
It notes in the paper "throttle response was excellent" so clearly this was a concern for Mopar.
A summary is here- http://www.thedodgegarage.com/turbo_sae_25.html
Working on clearing the decks.
I'm pretty certain the 1-piece isn't half as bad as it's been commonly believed for years...
What I said about airflow vs TPS opening is what changes on a larger TB, and no, I don't see how the adaptive ECU would deal with that since its something that was NEVER intended to change. The only way it would adapt for that might be with knowing what the atmospheric pressure is which would change some responsiveness in the engine. That has nothing to do with the Throttlebody.
Above, I said I don't seriously consider the velocity of the air through the TB mattering for the velocity of air that flows past the intake valves. The plenum kinda puts a stop to all that.
While I can't speak to what Gary mentions about T1 setups feeling less responsive with a larger TB, when you remove all the semi sketchy turbo setup and just have a simple n/a engine, yes, it makes a huge difference in throttle response. Its the case in ALL happy engines. It is why manufacturers make progressive throttlebodies or twin blade setups (one small, one large, etc).
Here is where I totally agree with you. The setups were only made for so much HP, and T1's were made for much less than even 175hp. I would never sacrifice for the masses to make a few tuners happy if ability to feed my family was on the line at the company.
The 3.0 moved to 46mm TB and stayed that way. The TB got smaller the same year the exhaust manifolds got larger. The plenum designs also changed. The HP rating remained about the same for 14 years.........Also, realize that the 3.3L came into being so they had to make sure the 3.0 made significantly less power, unlike the 3.0 12 valve put in some mitsibushi versions that were rated up to 180+hp with variable intake manifolds, big TB's, and different compression ratios.
The 52mm then became the mainstay for the 3.3L and 3.8, with the 3.8 eventually going 58mm.
As a manufacturer I wouldn't put a huge TB into an already developed factory turbo setup that I had no plans on matching the rest of the system too.
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If you are not trying to be fancy, its really really easy. Pretty sure I already bugged you about this a year or two ago.
Brent GREAT DEPRESSION RACING 1992 Duster 3.0T The Junkyard - MS II, OEM 10:1 -[I] Old - 11.5@125 22psi $90 [U]Stock[/U] 3.0 Junk Motor - 1 bar MAP [/I] 1994 Spirit 3.0T - 11.5@120 20 psi - Daily :eyebrows: Holset He351 -FT600 - 393whp 457ft/lb @18psi 1994 Spirit 3.0T a670 - He341, stock fuel, BEGI. Wife's into kid's project. 1990 Lebaron Coupe 2.2 TI/II non IC, a413 1990 Spirit 3.0 E.S. 41TE -- 1993 Spirit 3.0 E.S. 41TE -- 1994 Duster 3.0 A543 1981 Starlet KP61 Potential driver -- 1981 Starlet KP61 Parts -- 1983 Starlet KP61 Drag 2005 Durango Hemi Limited -- 1998 Dodge 12v 47re. AFC mods, No plate, Mack plug, Boost elbow -- 2011 Dodge 6.7 G56