Ported intake manifold and MPG

[Swordsmith]

Some time ago, TTR posted this:

Only item that we did notice, in which members do already, is port the manifold at the outlet side. We assume that rib is there to cause turbulence to atomize the fuel better at lower RPM. Porting should help top end air flow, but you may see a decrease in MPG do to the porting. We would consider it top end power increase @ the expense of giving MPG at cruising speeds. GM put it there for a reason...

What I like about the turbo Sonic is that I can have (relatively) large amounts of top end power, while being very economical at the low end. And the mods I have done have all been along those lines; I get more power when I really want it, but I still have the little fuel sipper most of the time driving around, because lets face it, most of the time, I'm just driving around and don't go anywhere near WOT.

Has anyone done a decent comparison of mpg on a ported vs OEM intake manifold? Is TTR correct, that there's a tradeoff to be made in terms of mpg vs power?

I think the tradeoffs I have seen thus far are quiet vs power (intake, exhaust), expense vs power(hard piped intercooler, E85 conversion), predictability vs power (tune that dumbs power down to that deliverable on a warm day), categories like that.

 

[krakenredbeard]

I noticed a mpg increase. Went from a average of 34 to around 37 and I can push it up to 40 in a rs.


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[Swordsmith]

That would be the opposite of what TTR expected. Not saying it isn't true, just... unexpected. Would love to see some serious testing done on this, you know, a tank with OEM intake, a tank with ported intake, both on same route same conditions and trying to drive the same (relying mostly on CC helps with that) and more than one car.

 

[krakenredbeard]

I don't know I've done so much so fast It could even be other mods. Etc. I just know I could barely get 34 before most of my mods and now I'm 37 and can push it to 40 if I really try.

It's hard to keep my foot out of it for more than one tank of gas lol.


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[Stew]

I didn't do back to back empirical testing but after porting the manifold my MPG didn't change. Tuned it and it still didn't change. Ported and tuned is still getting the same MPG as stock, averaging 38 to 39 MPG in my case.

What did really effect it was the unusually hot day (for Seattle area) yesterday of 96 degrees. Having the A/C blasting made a very big difference. Air conditioning also obviously makes a big difference in power available at the wheels.

The reason I mention that is there are things that do very noticeably lower fuel economy and power, porting the intake manifold isn't one of them.

 

[rsSteve]

I don't know I've done so much so fast It could even be other mods. Etc. I just know I could barely get 34 before most of my mods and now I'm 37 and can push it to 40 if I really try.

It's hard to keep my foot out of it for more than one tank of gas lol.


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I too actually noticed a mpg increase pretty significantly. I have a 14' rs, before porting I was averaging 34-35 with my commute to work. Next 2 tanks after porting I hit 36 then 38.9 mpg. This is on 87 octane and untuned. I just put 93 in for this tank and am curious to see what I hit. Maybe this is RS specific due to how high our rpms are at cruising speed. During my commute I set cruise at 62 mph (mostly flat roads) which is approx 2800 rpm. My theory is due to the higher rpms the better flow is helping us (rs's).

I definitely need more testing with a few more tanks to make sure it isn't a fluke. Also this is all very unscientific and just my experience. If I thought it would of helped I would of tried to eliminate as many variables as possible before I did this...

Not trying to derail the thread but people at cruze talk are claiming a slight loss of low end power as another side effect to this. I can not confirm nor deny this since I am untuned.

 

[ss2000slp]

Since porting the intake manifold, I have not noticed any decrease in fuel economy. Just an increase in fun at the top end. I did not do any direct back to back testing, but for the summer months last year (before porting) my average tank was always 35 to 36 mpg. So far this year since the weather warmed, every tank average has been 36-37. Not saying that porting the manifold accounts for the increase, just no noticeable decrease.

 

[Preloader]

I too actually noticed a mpg increase pretty significantly. I have a 14' rs, before porting I was averaging 34-35 with my commute to work. Next 2 tanks after porting I hit 36 then 38.9 mpg. This is on 87 octane and untuned. I just put 93 in for this tank and am curious to see what I hit. Maybe this is RS specific due to how high our rpms are at cruising speed. During my commute I set cruise at 62 mph (mostly flat roads) which is approx 2800 rpm. My theory is due to the higher rpms the better flow is helping us (rs's).

I definitely need more testing with a few more tanks to make sure it isn't a fluke. Also this is all very unscientific and just my experience. If I thought it would of helped I would of tried to eliminate as many variables as possible before I did this...

Not trying to derail the thread but people at cruze talk are claiming a slight loss of low end power as another side effect to this. I can not confirm nor deny this since I am untuned.

When you say "people on Cruzetalk (or AMSoiltalk as I like to call it)", are talking about the one guy that righteously tells people that modding is bad because GM has immaculate engineering and that any modifying second-guesses the supreme enlightenment of a group of guys that went to college for a couple years?

I stopped listening to that guy. He is waaaay to factual about his opinions.

 

[ss2000slp]

Well, my dyno graph is on here somewhere from last year, so when I go again (hopefully soon), should get a good idea on the difference in the power curve. If there is a loss, which I very highly doubt, I sure haven't felt it.

 

[ss2000slp]

Sorry, that last post didn't have anything to do with fuel economy. This one doesn't either, just wanted to hit 300 before I went to bed.

 

[Kuntryboy865]

Ive topped out at 35.4 mpg and all i do now is basically hwy driving.

 

[rsSteve]

Looks like the are basing it off the dyno graph by DDMworks, which does show a slight dip at the 3k mark but hard to say if you would even feel that tbh. Could be just the placebo effect after seeing the dyno chart.

Ported Intake Manfold, with results - Page 4

 

[RMinNJ]

Looking at the page 4 graph;
a.) It's for a DDMworks tuned car.
b.) The blue (no porting) line is below the black (ported) line everywhere except from about 2900 to 3200 where it goes higher... This must be "the dip".
c.) The difference in the dip looks to be about 12 ft/lbs if that.

If one torques their spark plugs at 15-19 ft/lbs.. I doubt one could possibly feel this.
It would be really nice to see a dyno of the stock tune and the stock tune ported where, perhaps, the torque difference is larger ?

 

[SoundWave]

I'm in-progress on some multi-tank MPG runs so I can get a good baseline before and after. My daily commute is 110 miles and 98% freeway so I have a good repeatable drive each week.

I'm setting my CC for the posted speed limit (mostly 70, but there is a nice big patch of construction that slows everyone down for a few miles)
I go through two tanks a week, with my weekend driving, but the weekend stuff is random, so I'll only be tracking my first tank each week after my Monday AM fill ups.

My car is currently got a stage 1 kit from BNR, and I'll be reporting based on the DIC and hand calculated MPG for as much detail as I can get. I figure three weeks un-ported then three ported should be enough miles for a reasonable sample.

I've also got an UG, which I'll reset at the start of both tests just to have an overall average for both conditions.

Any other ideas?


Typoed on my iPhone

 

[Hulty]

I'm the same as a lot of the others, with any mods that I've done, my MPG is good/bad depending on the weight of my right foot on any given day. Driving nice in 6th gear at 55-60mph I'm in the 38-40+ MPG depending on wind speed/direction, road gradient, etc. What I think is amazing is that I'd honestly say that I drive very aggressive 75+% of the time and if I let the MPG calculator go 2-3 weeks between resets I generally see an average of 33 MPG. I think that's pretty awesome for a car that sees real high RPM's the vast majority of the time. That's the largest reason why(other than the raw power output) that I don't have the slightest hesitation to put on 93 octane every fill up and I don't even look at the price.

In summary, damn I love my Sonic!!

 

[Swordsmith]

I don't have the slightest hesitation to put on 93 octane every fill up and I don't even look at the price.

With dozens of tanks of each, tracking both the mpg and $pg, it turns out I get more miles per dollar with 93 than with 87. So I don't not only not hesitate to put 93 in, I don't even see why I would consider it, and regret that I did put all those tanks of 87 in thinking I was trading a loss of power for a gain in savings.

 

[wickedsonic]

When you say "people on Cruzetalk (or AMSoiltalk as I like to call it)", are talking about the one guy that righteously tells people that modding is bad because GM has immaculate engineering and that any modifying second-guesses the supreme enlightenment of a group of guys that went to college for a couple years?

I stopped listening to that guy. He is waaaay to factual about his opinions.

Even in the perfect world where engineers dont screw up (and for those that dont know most arent automotive engineers leaving college they are engineers, who then get trained on automotive during their career by the manufacture) they could design the perfect manifold for us and then gm would send it back for

Day 1: make it cheaper
Day 2: small whistle at 3k (most customers wouldnt like) redesgn
Day 3: make it cheaper
Day 4: thats great but it hits the firewall when we install it
Day 5: The kids in korea at daewoo cant lift this , make it from paper
Day 6: Have you made it cheaper yet, we want .02 more profit.

Day 8: We heard kids might port these things, bend the etc opening around to fit behind the firewall and glove box area

So anyways, from what ive been told even when someone has a good idea there are so many c*$^blockers later on down the line it doesnt always matter.

 

[SoundWave]

Even in the perfect world where engineers dont screw up (and for those that dont know most arent automotive engineers leaving college they are engineers, who then get trained on automotive during their career by the manufacture) they could design the perfect manifold for us and then gm would send it back for

Day 1: make it cheaper
Day 2: small whistle at 3k (most customers wouldnt like) redesgn
Day 3: make it cheaper
Day 4: thats great but it hits the firewall when we install it
Day 5: The kids in korea at daewoo cant lift this , make it from paper
Day 6: Have you made it cheaper yet, we want .02 more profit.

Day 8: We heard kids might port these things, bend the etc opening around to fit behind the firewall and glove box area

So anyways, from what ive been told even when someone has a good idea there are so many c*$^blockers later on down the line it doesnt always matter.

Very good explanation, reminds me of this:

 

[ScarabEpic22]

I installed an intake at the same time when I ported the manifold so I cant say which change is contributing to any differences in MPGs.

Look forward to seeing how this thread pans out, be great if the MPG delta is either zero or positive! (Power above 4k doesnt fall off like before, pretty dang sure the intake isnt helping that so it's the manifold porting.)

 

[shorebreeze]

Couple of questions here. First, how tight are the tolerances on the Sonic? I.e., how well do the gasket and the manifold and the intake line up to start with?

Secondly, I see people with the high-revving, low-geared RS having some surprisingly good results with MPG from porting. What do you think is behind that improvement?

Third, what would happen with a more conventional set-up (1.4T, auto, LT)? Remember that the LT 6th gear is something like 20 percent longer than the RS one.

Fourth, does the improvement in performance impact the emissions, better, worse, etc? As others on the thread with boosted MPG have noted, it seems completely counterintuitive that porting the manifold would boost both performance AND efficiency, but that would suggest also better emissions performance, yes? Whereas the conventional scenario is more exhaust, more power, more emissions.

One other thing; I'm coming from two Prizms in a row. The first one, no VVT, just a straight-up DOHC four, did a little better on performance and mileage on high-octane fuel. The second one, with VVT, did not; no matter what you did with it, it turned in the same average performance, never poor, never great. Now I see people with VVT Sonics getting good results again from higher octane. What's behind that?