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Is this possible for the Fiero? by Letsbuildanexotic
Started on: 04-29-2011 02:09 AM
Replies: 23
Last post by: KraigG on 05-01-2011 01:43 AM
Letsbuildanexotic
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Report this Post04-29-2011 02:09 AM Click Here to See the Profile for LetsbuildanexoticSend a Private Message to LetsbuildanexoticDirect Link to This Post
There has been a lot of discussion on this board about gas prices, and trying to make your car more fuel efficient. I saw this video on youtube about a turbo vette, LS3 I believe, that at cruising speed can acomplish over 40 mpg. Check it out and since we have a few LS3 swaps here, would a turbo help or hurt? Many thing to concider is the accuracy of the corvettes MPG readout screen, the particular tune on the corvettes PCM, the corvette itself, wieght and frontal area, the gearing of the transmission, ect. ect. But, I rearly see turbo's put on a vehicle and MPG improved during normal driving. Now I'm sure once you put your foot into it, the MPG drops like crazy, but I would like to have a car with power when I need it, and high MPG's when I don't. And I think, someday, someone is going to find a swap that can do just that and hopefully it will become popular. Anybody know what the Eco-tech guys are getting for MPG's? I'm curious. Well, all are free to comment. I have no idea how truthful this video is, but it's facinating to me.



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Report this Post04-29-2011 04:34 AM Click Here to See the Profile for MaddMattClick Here to Email MaddMattSend a Private Message to MaddMattDirect Link to This Post
This was the idea behind my LZ8 swap, yes the cruising mps are up there. But when I stand on it...... what is killing my avg on the hwy is traffic and hills. There is a fair bit of computer fun to wire in to make it all work just righ, but I have a 45 min drive so I though it was worth it. I can get a video up of some hwy driving during the day.
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Report this Post04-29-2011 05:55 AM Click Here to See the Profile for AustralianClick Here to visit Australian's HomePageClick Here to Email AustralianSend a Private Message to AustralianDirect Link to This Post
Well the theory behind turbos were originally to increase power and fuel efficiency so mix the right amount of air and fuel and you should be able to improve economy on any motor.
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hyperv6
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Report this Post04-29-2011 07:18 AM Click Here to See the Profile for hyperv6Send a Private Message to hyperv6Direct Link to This Post
My Eco Turbo 2.0 is in a 3300 Pound HHR. Around town I see 23-24 Summer MPG and highway I see 31-32.

Note that the trick to the Eco Turbo is in the VVT and DI systems of the engine. These systems have a lot of tricks that provide economy. Thinks like when ever you get off rhe gas the fuel system shuts down all together. No fuel goes to the engine off throttle and in gear. The DI systems only puts in just what the engine needs on throttle and this is why the system will soom be on all engines.

Note too some weird things can be done to increase MPG. GM made a Turbo upgrade kit for my car. This moved the HP from 235 HP to 290 HP and torque to 315 FT LB with only a computer flash and two map sensors. While doing this GM Performance found 1-2 more MPG in this engine under normal driving conditions. The extra torque helps get the car up to speed easier and get the driver off the throttle sooner providing extra MPG. All of those who have installed this kit has seen similar results and it was also confirmed to me by the lead engineer that worked on this set up.

The instant MPG thing on the dash can be misleading at time. I can get mine to peg at 99 MPG but I will also never see that.

A similar engine in the Fiero should see as good or better MPG just because of the less weight.

Note if a Six speed transaxled was used it would also do much better as the HHR and Cobalt with this engine were saddled with the old 4 speed set up. The six speed would not fit without great changes to the vehicle.

Note like all other cars if driven hard the MPG can drop to 20 MPG city fast.
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Report this Post04-29-2011 08:16 AM Click Here to See the Profile for dobeySend a Private Message to dobeyDirect Link to This Post
Well, my 1.4 turbo Ecotec in my Cruze Eco is getting about 30-32 MPG around town in that car, and about 42-45 MPG highway.

But it is not the turbo that makes it get that sort of MPG. There are a lot of other changes to the Cruze Eco from the regular models that bump the MPG up. The LT/LTZ Cruze models also have the turbo 1.4. But the Eco has special wheels/tires, spoiler, and an active grille system to improve the drag coefficient and reduce rolling resistance.

It's going to take more than bolting on a turbo to get better MPG out of a car. What they're not telling you in that video is all the tuning they did to get that sort of MPG in an LS3 Vette. And it's only running about 1500 RPM at 70 MPH, with the gearing and tires on a stock 08 Vette. The STS turbos aren't doing enough at that RPM to make a 15 MPG difference.

There's almost certainly something else to that Vette they're not telling you in that video.
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Report this Post04-29-2011 08:22 AM Click Here to See the Profile for dobeySend a Private Message to dobeyDirect Link to This Post
 
quote
Originally posted by hyperv6:
The instant MPG thing on the dash can be misleading at time. I can get mine to peg at 99 MPG but I will also never see that.


Yeah, decelerate. This is basically because you are moving forward, at idle speed, and the math in the computer does not take into account the fact that you are probably coming to a stop. But as soon as you do, it drops back down to 0 MPG. So taking into account time spent at each MPG rating, it averages out correctly.

Now, in my Cruze Eco, I can cruze around town and see upwards of 50MPG actual, and it is true. But, it does average out to be much less, with all the stop and go having to deal with traffic lights.
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pontiackid86
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Report this Post04-29-2011 10:21 AM Click Here to See the Profile for pontiackid86Click Here to Email pontiackid86Send a Private Message to pontiackid86Direct Link to This Post
Cant say the turbo on my 88 helps with my fuel efficiency but thats what they were originally made to do. little bit of a burden on gasoline engines though because "most" turbo cars must run premium.
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Fiero84Freak
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Report this Post04-29-2011 10:38 AM Click Here to See the Profile for Fiero84FreakClick Here to Email Fiero84FreakSend a Private Message to Fiero84FreakDirect Link to This Post
 
quote
Originally posted by Letsbuildanexotic:
But, I rearly see turbo's put on a vehicle and MPG improved during normal driving.


What do you mean? That's actually the exact opposite. The reason why on the internet you're not seeing MPG improvements with turbo is because most who are running turbos are not putting them on for gas mileage - they're putting them on for the extra power they produce for the drivetrain, and thus the tune(s) they're running are not in the interest of MPG. The tune is in the interest of seeing the most power at the optimum point of spool time from the turbo. Obviously that's what the majority of the people on all Fiero forums are doing when the run turbos, but it's not the only way to make a turbo do it's job.

Actually, a turbocharger does a very good job - in a normal application - for improving engine efficiency. A primary example of this is in Japanese "Kei" cars (vehicles with displacement under 1 liter). Many Japanese "Kei" cars with turbochargers actually get well around 60 MPG (Imperial units) at Japanese highway cruising speed (which is right around 62-65 KPH, or I guess right around 50-ish MPH). In fact, in most applications an installation of a turbocharger is a rather efficient upgrade in the overall scheme of things. One just has to think about tuning for efficiency, rather than outright horsepower.

You have to remember that the primary way a turbocharger works is off of recirculated exhaust gases, and then one tunes air and fuel to properly deliver as not to cause detonation. You can create a tune that works in the interest of "steady" driving. A big deal would likely be actual turbo choice as well, which for such a particular application it would probably be in the best interest to choose a small turbo (like a DSM 14B) to ensure that spool time is at lower and steady speeds, rather than above steady and WOT speeding speeds. Many of the turbo guys here would probably know the best way of going about doing that, and could probably explain it better than myself. Again though the majority of aftermarket turbo applications are primarily in the interest of outright power that a turbocharger brings. MPG turbo setups are out there. Just no one is using them.
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Report this Post04-29-2011 11:25 AM Click Here to See the Profile for dobeySend a Private Message to dobeyDirect Link to This Post
 
quote
Originally posted by Fiero84Freak:
Actually, a turbocharger does a very good job - in a normal application - for improving engine efficiency. A primary example of this is in Japanese "Kei" cars (vehicles with displacement under 1 liter). Many Japanese "Kei" cars with turbochargers actually get well around 60 MPG (Imperial units) at Japanese highway cruising speed (which is right around 62-65 KPH, or I guess right around 50-ish MPH). In fact, in most applications an installation of a turbocharger is a rather efficient upgrade in the overall scheme of things. One just has to think about tuning for efficiency, rather than outright horsepower.


This is somewhat of an understatement. 65 km/h is 40 mph. Kei cars are limited in engine displacement and power. And many of the older ones are also 2-stroke engines instead of 4-stroke. To say that a turbo gives them significantly greater efficiency is a huge overstatement. What you're talking about here is making a slighly larger chassis and forming a body, on top of a Honda CBR-600. You can go buy a sport bike in the US right now and get 60 MPG if that's what you want.

Heck, cruising at 40 MPH, my Cruze Eco will net 60+ MPG, and that's with 2 more gears left to shift into. A 2.5 Fiero with the Isuzu trans probably could too.

That Vette in the video was tuned to run leaner at cruise. The turbos probably have absolutely nothing to do with the improved gas mileage in it.
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Report this Post04-29-2011 12:24 PM Click Here to See the Profile for MaddMattClick Here to Email MaddMattSend a Private Message to MaddMattDirect Link to This Post
The ls3 cuts down to 4cyl when crusing. I dont think the turbo had anything to do with the ecnomy, but it hepls an economy tuned motor have lots of power.
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Report this Post04-29-2011 12:38 PM Click Here to See the Profile for dobeySend a Private Message to dobeyDirect Link to This Post
 
quote
Originally posted by MaddMatt:

The ls3 cuts down to 4cyl when crusing. I dont think the turbo had anything to do with the ecnomy, but it hepls an economy tuned motor have lots of power.
Matt


The LS3 does not cut down to 4 cyl when cruising. The L76/L99 do, but I don't think the 2008 Corvette had them as an option. If you got a 2008 Corvette you got the LS3. Otherwise that 25MPG window sticker seems low.
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Report this Post04-29-2011 12:40 PM Click Here to See the Profile for eph_kayClick Here to Email eph_kaySend a Private Message to eph_kayDirect Link to This Post
I apologize if I read over somebody else saying this, and I could also be completely wrong, but one thing most people don't account for on the MPGs the car reads, is they are based on the duty cycle of the injectors. When people swap in a twin turbo kit into a corvette they tend to up the injectors size, which in turn makes it where the duty cycle of the injector while cruising is lower. Leading the computer to believe that the injectors are use less fuel thus getting better gas milage.

They didn't say they have done measured fuel consumption calculations to say they got 350-400 miles on 10 gallons of gas, they just said that the inst. MPG read out on a corvette that most likely doesn't have stock injectors or a stock tune, says it gets high mpg.

I have on the other hand read about people getting 1-2mpg from a twin turbo GTO with similar gear ratios and an LS2 tuned for the highest possible volumetric efficiency with a turbo during cruising speeds. But not getting 15mpg more.

Just my thoughts, Corvette sounded great with the turbos!

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Report this Post04-29-2011 03:53 PM Click Here to See the Profile for Fosgatecavy98Send a Private Message to Fosgatecavy98Direct Link to This Post
When I had my mostly bonestock L61 (2.2L) Ecotec swapped in my fiero with the MT2 transmission I got 47mpg (68~73mph) on the highway for road trips. It may even been a bit higher as I had about 1/4 of it was cruising around 60+stop lights/signs. A slightly higher gearing would be great as well, I don't think I ever needed to downshift once I was up to highway speeds.
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Report this Post04-29-2011 04:54 PM Click Here to See the Profile for PerKrClick Here to visit PerKr's HomePageClick Here to Email PerKrSend a Private Message to PerKrDirect Link to This Post
 
quote
Originally posted by dobey:


The LS3 does not cut down to 4 cyl when cruising. The L76/L99 do, but I don't think the 2008 Corvette had them as an option. If you got a 2008 Corvette you got the LS3. Otherwise that 25MPG window sticker seems low.


isn't 25MPG for mixed city/highway/backroads driving? I do know my father reported getting (approximately) 40mpg running steady at about 55-60mph in his LS2 C6. I honestly thought the LS2 had DOD, but a few google searches revealed that's not the case. So how does it get there?
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Report this Post04-29-2011 05:36 PM Click Here to See the Profile for dobeySend a Private Message to dobeyDirect Link to This Post
 
quote
Originally posted by PerKr:
isn't 25MPG for mixed city/highway/backroads driving? I do know my father reported getting (approximately) 40mpg running steady at about 55-60mph in his LS2 C6. I honestly thought the LS2 had DOD, but a few google searches revealed that's not the case. So how does it get there?


No. The window sticker ratings are City and Highway only, not mixed. They do show mixed in between the two, toward the bottom of the sticker. I think Mixed EPA rating for the 08 vette is 18 or 19.

I am pretty sure your father wasn't getting 40 MPG in a stock tune LS2 Vette. 40 KM/G maybe. Though at 55-60 in 6th gear, I would say more around 28-29 is probably reasonable in a stock LS2 Vette. You can't really say it's getting 40 MPG, even when the live reading says it is. When in top gear crusing around town in my Cruze, the live reading will be around 50-60 MPG. But I only average 30-32.
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Report this Post04-29-2011 05:53 PM Click Here to See the Profile for PerKrClick Here to visit PerKr's HomePageClick Here to Email PerKrSend a Private Message to PerKrDirect Link to This Post
 
quote
Originally posted by dobey:


No. The window sticker ratings are City and Highway only, not mixed. They do show mixed in between the two, toward the bottom of the sticker. I think Mixed EPA rating for the 08 vette is 18 or 19.

I am pretty sure your father wasn't getting 40 MPG in a stock tune LS2 Vette. 40 KM/G maybe. Though at 55-60 in 6th gear, I would say more around 28-29 is probably reasonable in a stock LS2 Vette. You can't really say it's getting 40 MPG, even when the live reading says it is. When in top gear crusing around town in my Cruze, the live reading will be around 50-60 MPG. But I only average 30-32.


ok, if you say so. isn't a 25% error a bit... excessive?
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Report this Post04-29-2011 06:01 PM Click Here to See the Profile for dobeySend a Private Message to dobeyDirect Link to This Post
 
quote
Originally posted by PerKr:
ok, if you say so. isn't a 25% error a bit... excessive?


Well all you have is hearsay evidence. Get some video, data logs, and a list of all modifications performed on the car. The live vs. average isn't a margin of error issue though. The EPA estimate is made by filling the car with gas, and driving it in a circle at a certain speed and determining how many miles were driven on that tank of gas. The 08 Vette with automatic came out at 25 MPG for the highway test.
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Report this Post04-29-2011 06:18 PM Click Here to See the Profile for nitroheadz28Send a Private Message to nitroheadz28Direct Link to This Post
 
quote
Originally posted by PerKr:


ok, if you say so. isn't a 25% error a bit... excessive?


The point is, the HUD mpg readings can be inaccurate, especially when making changes like swapping injectors as discussed above. The only real way to test mileage is to calculate what you get when you fill up at the pump. I also found it funny when watching that clip, considering that the Vette was sitting at just over 1500rpm and not boosting in any way... The turbo system isn't contributing anything at such a low cruising speed. I honestly can't see 40mpg out of such a large V8 in a Vette without DOD, maybe mid 30s under optimal conditions with proper mods to support that.
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hyperv6
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Report this Post04-29-2011 11:35 PM Click Here to See the Profile for hyperv6Send a Private Message to hyperv6Direct Link to This Post
 
quote
Originally posted by pontiackid86:

Cant say the turbo on my 88 helps with my fuel efficiency but thats what they were originally made to do. little bit of a burden on gasoline engines though because "most" turbo cars must run premium.


Today most factory GM cars have Premium fuel as recomended not required. GM wants to keep the option open to the owner on what he wants to use and not scare off buyers on turbo engines. Note if you use regular it can cost you boost and about 20-25 HP VS preium.

My HHR SS was recomends Premium till I did the GM upgrade and now it is Requred and they even include a sticker for the gas lid. My wifes 3800 SC Series III also has a recomended rating and I know it is 260 HP on Prem and 240 HP on reg. You can feel the difference. With todays knock sensors and computers it can dial in and out performance based on fuel being used. My old SSEI had the older 3800 SC Series II and it was Premuium Required only. They even noted that if you could not find premium to drive careful and no WOT starts or damage can occure.

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Report this Post04-30-2011 12:52 AM Click Here to See the Profile for Formula88Send a Private Message to Formula88Direct Link to This Post
Even if accurate, the instant MPG figures are misleading. Modern cars cut off the fuel flow when coasting and use "zero" fuel. Notice when he was decelerating, MPG went to over 70mpg. That doesn't mean you can expect to pull down 40-70 mpg even on a steady state highway cruise.

Still, for the power it puts out I'm sure it still gets good mileage, possibly better than stock. Heck, my 2000 LS1 Trans Am gets with 1-2 mpg of the same mileage as my 1988 2.8 Fiero.
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Report this Post04-30-2011 06:22 AM Click Here to See the Profile for hyperv6Send a Private Message to hyperv6Direct Link to This Post
 
quote
Originally posted by Formula88:

Even if accurate, the instant MPG figures are misleading. Modern cars cut off the fuel flow when coasting and use "zero" fuel. Notice when he was decelerating, MPG went to over 70mpg. That doesn't mean you can expect to pull down 40-70 mpg even on a steady state highway cruise.

Still, for the power it puts out I'm sure it still gets good mileage, possibly better than stock. Heck, my 2000 LS1 Trans Am gets with 1-2 mpg of the same mileage as my 1988 2.8 Fiero.


I was speaking of the boost gauge. Buy I agree on the Instant MPG.
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Report this Post04-30-2011 03:55 PM Click Here to See the Profile for drattsClick Here to Email drattsSend a Private Message to drattsDirect Link to This Post
I am almost ready to put my turbo ls4 on the road. I won't have a before and after so I'll never know if it increases or not, but car tuning says to expect 2-3 mpg better with the turbo. My friends Ls4 gets 30mpg easily so I'm hoping for 32-33 mpg. Not bad for 640 hp. Only downside is that I lose the low octane option, but I guess that with the low octane I was probably going to lose hp there due to knock sensor and timing.
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Report this Post04-30-2011 08:44 PM Click Here to See the Profile for rogergarrisonClick Here to Email rogergarrisonSend a Private Message to rogergarrisonDirect Link to This Post
both my Corvettes, the Caddy and Magnum had instant MPG readouts. Ive found all of them to be pretty accurate. Me and my buddy took my Magnum and his Charger to a car show. We zeroed the odometers and the mpg readouts and topped both cars off. At 100 miles exactly, we both had same readout using cruise control all the way. Topping both cars again, they took the same amount of gas and it was within a .1 of a gallon accurate of what the readouts said we used. If I remember my steady mpg reading was like 25, using 4.1 gallons, think his was 4.2. It took just a tick over 4 gallons to top them both off again.
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Report this Post05-01-2011 01:43 AM Click Here to See the Profile for KraigGSend a Private Message to KraigGDirect Link to This Post
I had a C5 Vette a few years back, and I got an actual 30+ mpg on the freeway. Obviously, I didn't have much of a performance rear axle ratio in it.
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