Good to know this. The ve pump engines are less noisy as well. These engines got very noisy when they went to 24 valves.

 

Best thing you can do to help fuel mileage is watch that right foot

 

Or stop driving.

 

I heard that if you keep the boost below 5psi and egt's below 750 while cruising it gets the best mileage. Also the sweet spot is around 1800 rpm.

 

y is the ve more efficient??? does the timing compensate for rpm on the ve pumps or somthing???

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hey i have heard of injectors that were supposed to increase mpg's
i talked to a guy once that said he took used injectors and honed them and shimmed them to 230 bar or somthing liked that and they were supposed to get better fuel economy and little bit better hp, he claimed with a 100 plate in stock location a 12v wouldnt even smoke

 

imho the reason for the ve being more efficient is mostly due to it requiring less power just to turn the pump its self. rumor has it that a modified p-pump can take 50 hp to run. thats more than some small automobiles had in the first place!
as for 1400rpm @65mph, i have never proven this but i would suspect that this is almost too slow, have you ever checked the ecconomy at the same speed but lower gear so ud be at possibly 1600 or 1700? but the other stuff sounds good. also, and this is important and most times over looked but i have proven it on my truck, the factory intake pipe is too small on your '89 engine. take it off and look inside it sometime, both ends. how did they figure that was gonna flow enough air for 359 cubes. at no or low boost it barely flows enough air to keep the stock fuel setting from making smoke. i made one out of full 2-1/2" pipe and it made a huge difference on power and smoke on takeoff and between gears. also the turbo doesnt flow enough air especially at low boost. again look at the size of the hole it has to go through especially with the fins of the compressor wheel in it. you need an hx40 size compressor wheel, possibly a complete hx40 turbo. the factory first gen dodge ic doesnt flow enough air either, look for somethin a little bigger.

 

You will get the most MPG at the highest TQ rating, 1800rpm.

 

Yes it does but its regulated by case pressure not RPM. But USUALLY case pressure raises with RPM.

 

ok got ya

 

I have also wondered what my fuel economy numbers would be at higher rpm’s. The main reason for running double overdrive is less noise. The engine runs a lot quieter. There is no hint of bogginess and no smoke. Going up a long 5-6% grade, I usually shift it out of double overdrive. The engine has enough grunt to maintain 65 mph at 1400 up a 7% grade. At a steady 65 mph in double overdrive, I'm getting 26 mpg.

Here’s my rpm’s at 65 mph.
5th gear = 2483
6th gear = 1837
Double = 1434

I’m running a big honking air filter / cold intake. This feeds the HX35 turbo. Take at a look at the picture below to see what I have.

I already replaced the turbo with an HX35 with a 12 cm housing. Would I still be better off with an HX40? Can I install an HX40 compressor wheel into what I already have?