Lessons Learned

[ttrainxl]

Pretty cool. I think today I’ll cut another vacuum tube at maybe five or six inches and see if that’s any different than my 8” tube. I don’t expect to see a difference though. Ill refuel and see what I’ve gotten with the 8” tube and compare it to the new tube.

If your brake booster vacuum tube is 15” and you have a 4.7L engine, that’s 3.19” per liter of vacuum tube. 3.19”x my 1.6L engine is 5.1”, so I think I’ll try something like that.

[steve05ram360]

Since your going to work on it , use a t to tap into the brake booster line and see if that makes a difference.

[ttrainxl]

Put a 16” vacuum tube on the brake booster line of my 1990 F150 with a 302 and think I might have gained a little low end torque. Seems like low and mid range are both a bit better. But I really rarely bring the engine up to 3000 rpms since the truck gets such bad fuel mileage, so maybe I am just not used to driving with as much throttle as I have it today. Again, I used an inlet and outlet on the tube, no T.

I think I’ll try the T on the new 5” tube for my civic and see if that does anything.

[steve05ram360]

So thats 3 engines now, 1 with definitely SOTP change, 1 with maybe a slight change and 1 with no SOTP change detected...

What did the civic end up doing for mpg's?

Yesterday I tweeked my tube setup, went back to the 9" piece connected straight to the manifold. Looking to get power up the rpms a bit. I am finding though that with higher rpms, mpg's seem to be better than lower. That is a head scratcher for me. With the current setup, trans still wants to upshift and cruise at 1400~1500 rpms at times which tells me there is still a good bit of bottom end boost, even with the attempt to shift the power up the rpms.

On the jeep, its update is delayed...had issues over the weekend and a 180* stat went in during an engine flush. Going to wait until I hear back on mpg's with the new setup. I expect it should still be in the 14-14.5 range.

[ttrainxl]

Gotta go out of town until the end of the month, so any other changes I make will have to wait. I’m flying out, so no personal vehicle for me. Hmm… maybe try it on the airport rental car!? : )

[steve05ram360]

I did this to the wifes Jeep Jk Wrangler over the weekend... did not feel anything close to what the Dakota showed. Installed a 12" section T'd off the brake booster line. She has been hand calculating her fuel and was un-aware her jeep had a LOM (Lie-o-Meter) for mpg's until recently. Here Jeep has historically been in the 12 mpg range with no long commutes to work (6 mi one way, most of it 35-45 mph backroads with 2 mi of freeway). Her jeep is a poster child for what not to do to get good mpg's... cut fenders, huge tires on heavy wheels powered by a tiny 3.8L mini van motor from dodge.

What I have done and what it did for mpg's...

1) Recalibrated the throttle body, this right away gave better throttle response and took mpg's from the 12's to the low 14's.

2) Installed a 4.7L throttle body, I believe it is 72mm and is referred to as the viper TB mod in the jeep world. This gave a noticeable bump in performance and the jeep no longer feels like its getting beat to death going up the taller grades that are local to us. 2 of them in particular you had to really get into the throttle just to keep the speed loss to 5 mph. RPMs were often in the 3000+ range. It seemed to me it was downshifting 2x a t times. Now there is just one downshift and it pulls the hills much better. I had to create a makeshift intake tube adapter to get this to work, the flow is pinched on the inside of the tube (has always been like that) and will be making a 3" setup from airbox to the throttle body. The 1st tank after this mod gave her a 15.1 mpg tank. At my request, she also reset the LOM when filling up on this tank. The LOM read 15.3 mpg so it was pretty close. She was so happy I was rewarded with slice of cheesecake on Fathers Day. Now that is a good motivator hahaha.

3) Next (Saturday) I installed the "potato launcher" mod as I call it... Felt nothing SOTP that really stood out. Having a full tank with just 3 miles on it and the LOM having been reset, we used the Jeep for all activities this weekend, 80~90 miles I'm guessing and the LOM is indicating a 16.7 mpg. Knowing the thing is not that accurate until miles pile up we are not getting excited by it.

This week she is ditching me for a getaway with her kids so the Jeep will be parked at the airport for several days. Will report back what the tank ended up at when I know.

[steve05ram360]

MPG's came in at 15.3 mpg. Going to take a step back on the jeep, pull the tube and upper intake manifold, wrap the fuel rail and lower intake manifold runners & replace the upper manifold gaskets as they appear to be leaking from egr gasses.

[steve05ram360]

So I have a bit of an update... While the dodge 4.7 engine performance changed noticeably with this update, the jeep did not. on a longer day trip with me driving I got the 23.3 mpg tank over 125+ miles. The wife on the next tank had some longer hiway runs and got a 17+ mpg tank. Both are pretty high for her jeep wrangler JK. Her in town mpg' however tanked on another tank and was coming in at 10.5 or so and then an 11.5 or so. Pulled the mod and her mpg's went back up to 15's on her normal drives.

So what I have learned... I believe the benefit will show if the intake manifold volume and the engine has the ability to make good vacuum overall. There have been a few scenarios where vacuum goes to 0 on the 4.7 truck engine and it becomes a total turd.

I have picked up a check valve to use on the 4.7 motor to see if I can improve on that condition where there is 0 vacuum. What I did was to put it inline with the bigger tube hooked up to the brake booster line and added a smaller vacuum line to the same cap as the brake booster line feed to that tube. 2 lines on the same cap. The thinking is when the vacuum in the IM is high, it draws a vacuum in the tube quickly but then when the throttle is opened up, it is bleeding air back into the tube at a slower rate. No idea if this will help or hurt, will have to drive it and see. There is a slight change in performance on the drive earlier in this config.

MPG's have been in the upper 18's to 19 mpg pretty consistently, and that is with a new gas leak at the top of the tank so i cant fill it 100% now as I did previously. I believe the leak is coming from pump seal and will be swapping it out soon. With the leak like it is, mpg numbers dont hold a lot of weight since there is fuel loss.

If the new config works out for the Dak, will duplicate on the jeep and see how it does. I did experiment with different sizes of tube on the jeep and the smaller tube performed better.