Gas mileage and boost poll

[65TerrorCuda]

For vehicles that you've owned or driven and added boost to, have you seen any change in fuel mileage? I've turbo'd 3 vehicles and blown my barracuda, and in all cases gained mileage either a small amount or a huge amount. One vehicle went from 23mpg to 29, only by adding a turbo.
Books I've read said you'll gain mpg potentially unless you're dale earnhardt'n it everywhere, but the internet is rife with "blowers cost mpg", which isn't my experience.
What's your experience?

 

[rumblefish360]

Now try and convince someone not really into cars about that increase in mileage. I’ve never had success.

 

[65TerrorCuda]

Now try and convince someone not really into cars about that increase in mileage. I’ve never had success.

I don't even understand people that aren't into cars. There's so much you can learn getting your hands dirty

 

[rumblefish360]

I agree. Having the rep at work, I was often asked questions. I have no problem answering them and talking about it. I thought it was great. People seeking knowledge. But like you said, sometimes, the concept goes right over their head. It’s OK. I get it.

For a lot of these guys, when they ask about how to do it. Build a car and related costs, most of the time I would tell them to just purchase a new car and be done with it since the cost is the same because they’re not doing the work themselves. For them, it’ll be a home run with a warranty.

 

[TT5.9mag]

My daily driver is a 3500 Chevy quad cab dually with an 8.1 vortec big block and an Allison 5 speed auto. Bought it new and put 200k miles on it before turbocharging it. For those 200k it averaged 12.1mpg. It now has 610k miles on it and for the last 400k (turbocharged) it’s averaged 14.6mpg. I record mileage every fill up and have since the beginning. On a long trip I’ve seen as much as 18mpg and if I’m hammering on it, which I do a lot, I’ve seen as low as 6mpg on a tank. With the turbo the mileage is better when you baby it and way worse when you hammer on it. 110lb injectors flow a lot of fuel.

 

[65TerrorCuda]

My daily driver is a 3500 Chevy quad cab dually with an 8.1 vortec big block and an Allison 5 speed auto. Bought it new and put 200k miles on it before turbocharging it. For those 200k it averaged 12.1mpg. It now has 610k miles on it and for the last 400k (turbocharged) it’s averaged 14.6mpg. I record mileage every fill up and have since the beginning. On a long trip I’ve seen as much as 18mpg and if I’m hammering on it, which I do a lot, I’ve seen as low as 6mpg on a tank. With the turbo the mileage is better when you baby it and way worse when you hammer on it. 110lb injectors flow a lot of fuel.

That's a pretty nice improvement, and holy crap that's a helluva lotta miles! Good work

 

[TT5.9mag]

That's a pretty nice improvement, and holy crap that's a helluva lotta miles! Good work

I think the increase has more to do with being able to dial in the tune up than anything else. I’ve never tuned a stock vehicle but I bet you could make some improvements in fuel mileage just with tuning. The manufacturers have to tune to a fairly wide margin of safety and have a huge window for environmental changes. I know a lot of the tuner “guys” advertise a fuel mileage tune if that’s what someone is after.
And I lied, it’s not 610k. As of right now it’s 612,380.

 

[mbaird]

A little bit of boost during part throttle driving should see better mpg due to the increase in cylinder pressure.

I am redoing a 93 Mazda B2600i 4x4 right now to use as a daily driver and am considering either an Eaton M60 or a small turbo for better mpg and more HP than the 129 it came with stock .

 

[65TerrorCuda]

I think the increase has more to do with being able to dial in the tune up than anything else. I’ve never tuned a stock vehicle but I bet you could make some improvements in fuel mileage just with tuning. The manufacturers have to tune to a fairly wide margin of safety and have a huge window for environmental changes. I know a lot of the tuner “guys” advertise a fuel mileage tune if that’s what someone is after.
And I lied, it’s not 610k. As of right now it’s 612,380.
View attachment 1716167493

That is friggin awesome my friend.

A little bit of boost during part throttle driving should see better mpg due to the increase in cylinder pressure.

I am redoing a 93 Mazda B2600i 4x4 right now to use as a daily driver and am considering either an Eaton M60 or a small turbo for better mpg and more HP than the 129 it came with stock .

Is that the v6 or the 2.3? Either way sounds like a great idea

 

[mbaird]

That is friggin awesome my friend.

Is that the v6 or the 2.3? Either way sounds like a great idea

2.6 … the last real Mazda truck

 

[65TerrorCuda]

@TT5.9mag
So what tuning did you end up doing? With a laptop or stand alone ecu etc?

I've considered turboing my only stock vehicle, a 95 tacoma 4x4 dual stick 4-banger, but then I'd have to do the clutch etc. It's already marginal lol.

Nice mazda! My dad had a 96 ranger, and doing the timing belt on that guy was a dream

 

[mbaird]

@TT5.9mag
So what tuning did you end up doing? With a laptop or stand alone ecu etc?

I've considered turboing my only stock vehicle, a 95 tacoma 4x4 dual stick 4-banger, but then I'd have to do the clutch etc. It's already marginal lol.

Nice mazda! My dad had a 96 ranger, and doing the timing belt on that guy was a dream

I bought a 95 Taco 4x4 std cap with a 2.7 new . Great truck ! In fact my favorite out of all the trucks I have owned . Had a 99 X-cab TRD as well with V6
but liked how the 95 was balanced and that 2.7 was just a sweet engine .

 

[YY1]

Turbo is basically "free" HP.

The engine doesn't have to work as hard and it costs next to nothing to spin the turbo.

 

[65TerrorCuda]

I bought a 95 Taco 4x4 std cap with a 2.7 new . Great truck ! In fact my favorite out of all the trucks I have owned . Had a 99 X-cab TRD as well with V6
but liked how the 95 was balanced and that 2.7 was just a sweet engine .

I love it, got it at auction with 160k miles. I would've preferred single cab but the extra cab comes in really handy

 

[TT5.9mag]

@TT5.9mag
So what tuning did you end up doing? With a laptop or stand alone ecu etc?

I've considered turboing my only stock vehicle, a 95 tacoma 4x4 dual stick 4-banger, but then I'd have to do the clutch etc. It's already marginal lol.

Nice mazda! My dad had a 96 ranger, and doing the timing belt on that guy was a dream

My truck is on the factory GM ecu tuned with either EFI live or HP tuners. Both on a laptop. It’s been tuned on a chassis dyno twice by “tuners”, one that was not so good, and countless times while driving. I give a lot of credit to blackbear performance tuning for how good it is now, as he got it straightened out beautifully after the first chassis dyno session and a botched tune. That was all 15 years ago. I tune it myself now with HP tuners but I don’t make significant changes to anything really. I did a lot of “decel fuel cut” tuning and shift strategy (shift timing and torque management) for the Allison myself. Honestly I haven’t plugged in to it In probably 5 years. I’m happy with where it’s at.

 

[TT5.9mag]

A little bit of boost during part throttle driving should see better mpg due to the increase in cylinder pressure.

Any time you’re in to positive manifold pressure you’re using a bunch more fuel than you would be NA at the same load and throttle position. And on boost you’d better be quite a bit more rich than you could be NA.

 

[TT5.9mag]

Turbo is basically "free" HP.

The engine doesn't have to work as hard and it costs next to nothing to spin the turbo.

Very true, there is no parasitic loss with a turbo. But it’s not really free. Backpressure in the exhaust pre turbo has an effect on power as anytime I’ve seen backpressure go up, power goes down. That’s the trade off, and why sizing the turbo properly and designing an efficient header/manifold set up is so important. You will always have backpressure with a turbo, it’s a given, but limiting it has big benefits. At big boost/hp levels there is a lot to be gained by keeping the ratio between backpressure and boost pressure low.

 

[mbaird]

Any time you’re in to positive manifold pressure you’re using a bunch more fuel than you would be NA at the same load and throttle position. And on boost you’d better be quite a bit more rich than you could be NA.

my thinking is that during low rpm operation most engines are not getting optimal cylinder filling and that is where a supercharger is going to help efficiency. Of course if you are driving aggressively you will consume more fuel .

 

[TT5.9mag]

my thinking is that during low rpm operation most engines are not getting optimal cylinder filling and that is where a supercharger is going to help efficiency. Of course if you are driving aggressively you will consume more fuel .

Volumetric efficiency certainly will increase across the rpm range but that does not necessarily translate to fuel economy.

 

[rumblefish360]

I agree with both of you. One of the things about adding boost is lightening up the parasitic load. The additional fuel has to be minimal along with the amount of boost to increase mileage. 1-2-3 psi and most times mileage goes up. 8-9-10 psi, ehhhhhhhhhhh
Not so much! LOL!

 

[mbaird]

Agreed…. I am thinking 5 psi at most . If I was looking to hotrod it I would stuff a V6 in and turbo it .

 

[TT5.9mag]

I’m not sure how to explain it better than I already have but I’ll try again. How bout a question, what afr would you like to see at maybe half throttle 2800 rpm and 3 psi of positive manifold pressure? I’d like to see about 11.8-12.2 around there. And with no boost (N/A) at the same load and throttle opening you'd likely just be in to fuel enrichment/power valve opening and probably be 12.8-13.2. The sole reason boost makes power is because you can burn more fuel. You will not get better mileage if you are in positive manifold pressure because you’re burning more fuel. You “can” get better mileage light throttling it BEFORE reaching boost because the engine is not working as hard to draw in air because the turbo/supercharger is moving more air than the N/A engine would be and hasn’t made positive pressure yet and therefore doesn’t require the enrichment at that point.

 

[rumblefish360]

An AFR like it’s N/A except under boost where you need more. FI is excellent here.

 

[mbaird]

My Mazda is multiport injected .

I am trying to think this thruogh….wouldnt the increased efficiency translate into less throttle input required for the same excelleration translating into better mpg ?
There has to e a reason all the modern cars have smaller turbo/supercharged engines . Granted they have direct injection , optimal chambers , bett management systems etc….

 

[rumblefish360]

My Mazda is multiport injected .

I am trying to think this thruogh….wouldnt the increased efficiency translate into less throttle input required for the same excelleration translating into better mpg ?

Mileage, yes, acceleration? No. You still need to make the power to move the weight. While there is an improvement, the amount is not seen in mileage.

There has to e a reason all the modern cars have smaller turbo/supercharged engines . Granted they have direct injection , optimal chambers , bett management systems etc….

True. But sometimes I can effectively play devil advocate. Allow me to do so here, just for fun.

Todays cars get what rod mileage?
Plymouth (perhaps Dodge?) had a Cricket that for what rod mileage?
In yeasteryear games the government set up between the manufacturers, specifically, the “How gets the best mileage.” game, who won most often, with what car and drive train getting what rod mileage?

Ooooooooooo!!!!!!

Can the FABO gang come up with the answers to the mileage masters?