The Chrysler Minivan Fan Club Forums banner

1 - 20 of 36 Posts

·
Registered
Joined
·
275 Posts
Discussion Starter #1
What do y'all think about the throttle body swap, taking a 3.8TB and putting on a 3.3. Some think it's a viable mod. Don't want to get into a whole thing. Just curious

Sent from my SM-G950U using Tapatalk
 

·
Registered
2009 Dodge Grand Caravan SXT 4.0
Joined
·
520 Posts
Is the TB opening on the intake manifold the same diameter as the 3.8 TB? If not, then it's a waste.
 

·
Latent car nut
Joined
·
9,061 Posts
Lots of anecdotal reports say it helps, other say, no help at all. My take is, the designers of the 3.3 and 3.8 liter twins aren't stupid, if a simple throttle body upgrade would improved power and driveability, they would have done it at the factory. The fact is, it cost Chrysler MORE to make two different throttle bodies then it would have cost them to make just one.
 

·
Registered
07 Grand Caravan (3.3L), 14 Dart SXT (2.0L)
Joined
·
245 Posts
I'm also curious about this mod. Some say the 3.8 TB is bigger than the 3.3 while online I see some parts say it fits both cars and some say it only fits one or the other. I'm going to get my 3.8 TB next week or two and I'm going to make a post with pics and all of my personal experience of driving the car with and without the 3.8 TB.

From what I can tell the 3.8 DOES have a bigger throttle body as most sites list it as two different parts. And forum members have said it looks bigger. Now about making more horsepower I could only see this happening at WOT. When you think about it more air means higher RPM, so if you drive around town at 1-2.5k RPMs your opening your bigger throttle body only so much so that it keeps the airflow you would have had with the smaller ones, but, with less pedal travel. This "less pedal travel" can make you "feel" like the car has made more power everywhere. Until you reach that certain point, let's say like 80% throttle, where the bigger TB would actually be feeding more air into the plenum making more ponies.

A bigger TB should definitely make the car "feel" more responsive which is what I'm looking for and at WOT it should make more ponies. So I'm going to test it and make yet another post for you guys :)

EDIT: BUT! If the inlet on the plenum is only so big... it wont matter how big the TB is...
 
  • Like
Reactions: Mopar-Mofun

·
Registered
Joined
·
275 Posts
Discussion Starter #7
I'm also curious about this mod. Some say the 3.8 TB is bigger than the 3.3 while online I see some parts say it fits both cars and some say it only fits one or the other. I'm going to get my 3.8 TB next week or two and I'm going to make a post with pics and all of my personal experience of driving the car with and without the 3.8 TB.

From what I can tell the 3.8 DOES have a bigger throttle body as most sites list it as two different parts. And forum members have said it looks bigger. Now about making more horsepower I could only see this happening at WOT. When you think about it more air means higher RPM, so if you drive around town at 1-2.5k RPMs your opening your bigger throttle body only so much so that it keeps the airflow you would have had with the smaller ones, but, with less pedal travel. This "less pedal travel" can make you "feel" like the car has made more power everywhere. Until you reach that certain point, let's say like 80% throttle, where the bigger TB would actually be feeding more air into the plenum making more ponies.

A bigger TB should definitely make the car "feel" more responsive which is what I'm looking for and at WOT it should make more ponies. So I'm going to test it and make yet another post for you guys :)

EDIT: BUT! If the inlet on the plenum is only so big... it wont matter how big the TB is...
What about the tps iac does not the pcm come in to play, as with the air intake mod?

Sent from my SM-G950U using Tapatalk
 

·
--UNKNOWN MEMBER--
Joined
·
12,676 Posts
I'm also curious about this mod. Some say the 3.8 TB is bigger than the 3.3 while online I see some parts say it fits both cars and some say it only fits one or the other. I'm going to get my 3.8 TB next week or two and I'm going to make a post with pics and all of my personal experience of driving the car with and without the 3.8 TB.

From what I can tell the 3.8 DOES have a bigger throttle body as most sites list it as two different parts. And forum members have said it looks bigger. Now about making more horsepower I could only see this happening at WOT. When you think about it more air means higher RPM, so if you drive around town at 1-2.5k RPMs your opening your bigger throttle body only so much so that it keeps the airflow you would have had with the smaller ones, but, with less pedal travel. This "less pedal travel" can make you "feel" like the car has made more power everywhere. Until you reach that certain point, let's say like 80% throttle, where the bigger TB would actually be feeding more air into the plenum making more ponies.

A bigger TB should definitely make the car "feel" more responsive which is what I'm looking for and at WOT it should make more ponies. So I'm going to test it and make yet another post for you guys :)

EDIT: BUT! If the inlet on the plenum is only so big... it wont matter how big the TB is...
Guys already measured and posted pictures, no need for more.

Assuming you are already running closed loop and not WOT or close. Even then, best case scenario your new and bigger TB would behave like the old one. No way that you can feel any power gain. At WOT your PCM will not compensate at all, Am I wrong?
Reviving an old thread here...

Pulled a 3.8 TB and swapped it into my 3.3 just now.

I heard you folks like photos, here are some side-by-side with a tape measure I took to show the difference. I see 2-1/4" vs 2-1/2" ID.

I'll post back with my Seat Dyno results after the commute home tonight.
Best upgrade for the least amount of money!

Greetings one and all, even the naysayers. Sorry it has taken me so long as I have been sick. Here are pictures of the throttlebody surgery. Even a timed photos of how long it took to remove. First picture is of the throttlebody before cleaning and prep. Second picture is of a throttlebody cleaned up. Make sure you plug or remove electrical components as throttlebody cleaner can affect them. Third is showing measurement of new throttlebody it is 65 mm compared to the old throttlebody of 58 mm. Four & five pictures are throttlebody brush cleaned up and ready to install.
As others had done ... taking some measurements

View attachment 54369

View attachment 54371

View attachment 54373

View attachment 54375


See next posting
This thread is useless to me, but it is fun to read.

For those new to this, I believe RIP proved me wrong one time, he included documentation showing restricting the intake air "will not" affect mileage. So, anything you do on that area will not increase MPG, doesn't matter what you think. It might help with performance, but not with MPG.

Now, if you want to really know if replacing your throttle body will increase power, just go to any racing-performance forum and find out for yourself. They do it all the time, it might help during WOT but that is about it. If you think about it, other than during WOT, you are restricting air flow through your throttle body via your accelerator pedal, only during WOT more air will be allowed to flow. Installing a bigger throttle body only make it harder to control during normal driving.

People who replace throttle body usually also replace other things, then they get a little better performance and claims it was due to the bigger throttle body.

Regarding MPG, "I can make" my vehicle show an instant or average 40 MPG+ on my EVIC, but I know if not true.

I have many vehicles, including some race cars, I know what I'm saying.

You guys have fun.

:happy1:
And I already posted the only difference is you need to push accelerator pedal a little bit less with the 3.8 throttle body.

Valves only allow so much air to go throughout. Without other modifications, you are just fooling yourself.

I actually agree with you.

What I don't agree, is people doing an "upgrade" that doesn't work and claiming it does, then encouraging others to do it when they know is not going to work.

Someone here posted his vehicle now have better response, I think he feels like his vehicle has now better response, but in fact it is exactly the same but, since he now have a bigger throttle body, it now respond quicker. It is like pushing the gas pedal a little more on the old throttle body, nothing else. Now, once you push it to WOT, then yes, it,"might" work a little better. People on the racing industry knows it, they do calculations to know exactly how big a throttle body they need, they just don't go for the biggest one they can get their hands on.
 

·
Registered
Joined
·
2,143 Posts
An engine's power is created by its ability to get air and fuel in, combust it, and get it out. The better it can do any of those, the more power it makes. There are a lot of nuances to each of those three things, of course. There are also compromises made to power in the name of NVH and economy and emissions. I am no expert on the complete picture, but I do subscribe to the "incremental improvement" side of things. So I'd say, be aware that a bigger tb means more air through it at any given throttle angle. The pcm will have fuel curves related to particular angles and may be a bit overwhelmed by excess air at low angle situations. It should be able to figure mostly out, but might not be perfect. If your engine is MAFless (I don't know when Chrysler used MAFs), that is one less thing to calibrate to a different tb size.

My experience with changing tb sizes is on a supercharged 3800 GM vehicle with a MAF. I changed the intake and supercharger to get inlet sizes to match as well. At cool temps, it runs so hard compared to original. When it gets more heatsoaked on a warm day, it pulls back noticeably. Granted, it has not been tuned but I've done swaps to the fuel delivery parts to bring the fuel trims back closer to 0 where they should be. It's a bit of a frankenstein, engine wise. The MAF is right in the TB where the size difference is, so the pcm is pretty vulnerable to changes there. Taking that vulnerability away, I feel like is probably an asset in terms of the pcm being happy.

I'd look at the 3.3 and 3.8 intakes, and if they are the same size, I would also feel good that the tb is going to help.
 

·
Registered
Joined
·
2,860 Posts
Shouting from the hills, the rafters, the rooftops, use third gear, use third gear! Simple, cheap, and the thrills will warm your heart.
 

·
Super Moderator
Joined
·
25,096 Posts
  • Like
Reactions: Mopar-Mofun

·
Registered
2006 Dodge Caravan SXE
Joined
·
801 Posts
EDIT: BUT! If the inlet on the plenum is only so big... it wont matter how big the TB is...
Yes, the plenum opening is BIG. Yes, the either the 3.3L TB or the 3.8L TB is smaller. When those part places say they are the same for size, it's for the outside casting and the mounting. It's not the TB opening for the air to pass thru.

After 1 week or a little more, the PCM and the UltraDrive re-learned the new 3.8L TB. Each time I drove, things actually got better and better in the 1st week. I've posted in the past the many benefits and improvements too.

Yes, I would like to hear both your first impressions and about 2 weeks out. (y)
 
  • Like
Reactions: TechiePocket1

·
3rd Gen Plebeian
Joined
·
507 Posts
The most bang for your buck way to hotrod a 3.3L is to put a 3.8L camshaft in it. But, at that point you might as well just swap the whole 3.8L in.
The 3.8L camshaft has longer duration and higher lift. You'd get a lot more top end performance with this in a 3.3L, though you'd lose some torque in the low end.

59610

59611

59612
 

·
Banned
2013 Dodge Grand Caravan
Joined
·
1,067 Posts
A larger throttle body without a larger intake doesn't allow any more air in than before at WOT. All you change is the throttle response. It will be like giving it an extra 5% (number pulled from arse) throttle compared to before.

If the intake is undersized for the throttle body you may see improvements in air volume, but not as much as switching intakes. Any restriction behind the throttle body will limit its ability to improve performance. With the 3.3 intake plenum being narrower than the throttle body, that will inhibit the engine from pulling all the throttle body can allow.

Throttle response is good, but this alone won't make more power on the top end.
 

·
Banned
2013 Dodge Grand Caravan
Joined
·
1,067 Posts
With the 3.8 cam, is the extra duration and lift an issue though? Pretty sure the stroke is different on these. Valves slapping pistons make no power.
 

·
3rd Gen Plebeian
Joined
·
507 Posts
A larger throttle body without a larger intake doesn't allow any more air in than before at WOT. All you change is the throttle response. It will be like giving it an extra 5% (number pulled from arse) throttle compared to before.

If the intake is undersized for the throttle body you may see improvements in air volume, but not as much as switching intakes. Any restriction behind the throttle body will limit its ability to improve performance. With the 3.3 intake plenum being narrower than the throttle body, that will inhibit the engine from pulling all the throttle body can allow.

Throttle response is good, but this alone won't make more power on the top end.
There is also an argument to be made for air velocity too. Having a larger throttle body will likely just reduce the velocity of the air flowing through it, having a smaller throttle body will increase the speed of the airflow.
For small changes in diameter, there won't be any changes in airflow, just a change in velocity.

I'm not qualified to comment on which is better, small and faster or larger and slower. I do know there are adverse consequences to running too large of an exhaust pipe, header pipe, or intake runner, but I wouldn't know the math to figure that out for throttle bodys
 

·
3rd Gen Plebeian
Joined
·
507 Posts
With the 3.8 cam, is the extra duration and lift an issue though? Pretty sure the stroke is different on these. Valves slapping pistons make no power.
I'm not sure if the pistons are different, there could be reliefs on the 3.8.
The heads appear to be identical, the valves are the same size. IIRC the 3.8L is a higher compression ratio, so the piston is actually taller than on the 3.3L. If that's true, you'd have more valve clearance on a 3.3L with a 3.8L Camshaft.
 

·
3rd Gen Plebeian
Joined
·
507 Posts
I'm not sure if the pistons are different, there could be reliefs on the 3.8.
The heads appear to be identical, the valves are the same size. IIRC the 3.8L is a higher compression ratio, so the piston is actually taller than on the 3.3L. If that's true, you'd have more valve clearance on a 3.3L with a 3.8L Camshaft.
I've been thinking about swapping a 3rd gen 3.8 block with 4th gen heads and cam into my '97 because the top end is so much better on the 2001+. Gotta find time to tinker in a junk yard to sort out the differences.
 

·
Banned
2013 Dodge Grand Caravan
Joined
·
1,067 Posts
The 3.8 has 1/4" more stroke than the 3.3. If you take that to mean both ends of the stroke are 1/8" longer, you could rev the 3.3 with a 3.8 cam until the chain snapped and still wouldn't strike valves. That is assuming connecting rod length and piston to valve clearances are the same between engines in their stock form.
 

·
Registered
2005 Dodge Grand Caravan C/V
Joined
·
188 Posts
Shouting from the hills, the rafters, the rooftops, use third gear, use third gear! Simple, cheap, and the thrills will warm your heart.
And as said before, dropping it in third doesn't do squat besides keeping overdrive from engaging. It doesn't add power, change other gear's ratios, or anything else that changes how the van runs.
 
1 - 20 of 36 Posts
Top