Any easy, cheaper ways to increase MPG?

Want to know how to get more out of your Beretta? Or have a mod you would like to share?
Cam2363
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Re: Any easy, cheaper ways to increase MPG?

Post by Cam2363 »

Rettax3 wrote:It takes me ten miles just to get out of my neighborhood... :D Yeah, short trips are hard on an engine, and MPG. I still think you should be seeing better than you've been getting (remember that Woody's engine isn't stock -lots of top-end work, cammed, etc), but with the summer fuel mix coming in, it looks like you are getting something a little better. :good:
I hope so. I would actually love to do some top and work soon because it seems a lot easier than the bottom end. Besides the cam ofcourse, just with the intake system


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Rettax3
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Re: Any easy, cheaper ways to increase MPG?

Post by Rettax3 »

If you aren't up for a full engine-swap, simply upgrading the heads, intake, and throttle-body to a J-code 3100 or 3400 works wonders for these engines. You CAN leave the heads for the M-code 3100 and still get some real performance gains (what my 'old' '95 Z-26 has had done to it), but you have to modify the bottom of the lower intake manifold with a Dremel or other small grinder to clear the taller rockers of the M-code heads. There are a couple of other minor details, like the heater-core hose outlet, maybe the upper radiator hose (I don't recall off the top of my head) and EGR -which should just be deleted and blocked-off anyway IMO. Sorry to say it now, but you were half way there time-wise when you fixed your LIMG earlier on. :pardon:


1989 SuperCharged 3800 Srs-II (First)Six-Speed GTU
1990 Turbo 3.4 5-Speed T-Type
1990 4.0L 4-Cam 32-Valve V-8 5-Speed Indy GTi (Project)
1990 Stock(!) 3.1 MPFI Auto Indy
1995 LA1/L82 4T60E Z-26
1995 3.4 DOHC Turbo 5-Speed Z-26
Cam2363
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Re: Any easy, cheaper ways to increase MPG?

Post by Cam2363 »

Rettax3 wrote:If you aren't up for a full engine-swap, simply upgrading the heads, intake, and throttle-body to a J-code 3100 or 3400 works wonders for these engines. You CAN leave the heads for the M-code 3100 and still get some real performance gains (what my 'old' '95 Z-26 has had done to it), but you have to modify the bottom of the lower intake manifold with a Dremel or other small grinder to clear the taller rockers of the M-code heads. There are a couple of other minor details, like the heater-core hose outlet, maybe the upper radiator hose (I don't recall off the top of my head) and EGR -which should just be deleted and blocked-off anyway IMO. Sorry to say it now, but you were half way there time-wise when you fixed your LIMG earlier on. :pardon:
Yeah I know. I didnt think about doing it at the time. I want to, but am scared of damaging the engine beyond repair and needing to get a new engine.

And what benefits does having the EGR blocked off give?

I also dont believe the upper rad hose is a problem as a friend of mine has a 3400 and his is in the exact same spot if I remember correctly, but I very well could be remembering it wrong.


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Rettax3
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Re: Any easy, cheaper ways to increase MPG?

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For EGR, once your engine has gotten some mileage on it, the carbon build-up inside the intake starts to have a negative effect. It collects on the intake valves too. Eventually, there is enough crud left in the engine to cause minor efficiency loss. It just makes the intake a mess overall, and is made worse with the PCV system too. Blocking it off keeps the valve from allowing hot, dirty exhaust gasses from flowing into your intake -this CAN even cause increased wear inside the engine, though I am not familiar with any tests that prove this is significant. If the valve gums-up or otherwise fails, it can also allow exhaust into the intake when it isn't supposed to, which can cause poor performance and driveability issues too (just another system to break down). The benefits of the EGR system are to reduce intake vacuum slightly without having to add throttle (and thereby gas) to reduce the engine drag (extremely minor effect), but the primary function is to increase the temperatures inside the combustion-chamber at low throttle settings (like highway cruise) to reduce certain emissions and help keep the catalytic converter operating properly. IMO, if you are shooting for 200,000 miles from your engine, unless you are planning on removing and cleaning the intake and scrubbing your valves, it does more harm than good. If you are going to junk your car at 80k, then it has served a positive function in reducing emissions.

On a '95, you MIGHT get a check engine light from blocking off the EGR -mine does trigger sometimes. It throws a code on my '90 Indy, but never sets the MIL (Malfunction Indicator Lamp) for it, so who cares?

On the upper radiator hose, I am pretty sure it stayed stock Beretta, just wasn't 100% sure, so figured I should mention the possibility.

I like the way my lightly modded 3100 runs in my Z, it definitely will ruin a stock '95 Z on the road, and I just put 301 miles on 12.46 gallons with some 'spirited' driving and zero highway driving on this tankful... :pardon:


1989 SuperCharged 3800 Srs-II (First)Six-Speed GTU
1990 Turbo 3.4 5-Speed T-Type
1990 4.0L 4-Cam 32-Valve V-8 5-Speed Indy GTi (Project)
1990 Stock(!) 3.1 MPFI Auto Indy
1995 LA1/L82 4T60E Z-26
1995 3.4 DOHC Turbo 5-Speed Z-26
Cam2363
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Re: RE: Re: Any easy, cheaper ways to increase MPG?

Post by Cam2363 »

Rettax3 wrote:For EGR, once your engine has gotten some mileage on it, the carbon build-up inside the intake starts to have a negative effect. It collects on the intake valves too. Eventually, there is enough crud left in the engine to cause minor efficiency loss. It just makes the intake a mess overall, and is made worse with the PCV system too. Blocking it off keeps the valve from allowing hot, dirty exhaust gasses from flowing into your intake -this CAN even cause increased wear inside the engine, though I am not familiar with any tests that prove this is significant. If the valve gums-up or otherwise fails, it can also allow exhaust into the intake when it isn't supposed to, which can cause poor performance and driveability issues too (just another system to break down). The benefits of the EGR system are to reduce intake vacuum slightly without having to add throttle (and thereby gas) to reduce the engine drag (extremely minor effect), but the primary function is to increase the temperatures inside the combustion-chamber at low throttle settings (like highway cruise) to reduce certain emissions and help keep the catalytic converter operating properly. IMO, if you are shooting for 200,000 miles from your engine, unless you are planning on removing and cleaning the intake and scrubbing your valves, it does more harm than good. If you are going to junk your car at 80k, then it has served a positive function in reducing emissions.

On a '95, you MIGHT get a check engine light from blocking off the EGR -mine does trigger sometimes. It throws a code on my '90 Indy, but never sets the MIL (Malfunction Indicator Lamp) for it, so who cares?

On the upper radiator hose, I am pretty sure it stayed stock Beretta, just wasn't 100% sure, so figured I should mention the possibility.

I like the way my lightly modded 3100 runs in my Z, it definitely will ruin a stock '95 Z on the road, and I just put 301 miles on 12.46 gallons with some 'spirited' driving and zero highway driving on this tankful... :pardon:
Alright. I might look into that.

And oh my goodness. I get about 210 to like 13.5 gallons. Please tell me all your secrets. I cant afford this anymore[emoji23]

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Mkweaver1958
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Re: Any easy, cheaper ways to increase MPG?

Post by Mkweaver1958 »

My 90 Indy gets a steady 21.8 mpg with mixed driving. Best ever was 28 full highway trip.


Cam2363
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Re: Any easy, cheaper ways to increase MPG?

Post by Cam2363 »

Mkweaver1958 wrote:My 90 Indy gets a steady 21.8 mpg with mixed driving. Best ever was 28 full highway trip.
Nice. What engine do you have?


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Rettax3
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Re: Any easy, cheaper ways to increase MPG?

Post by Rettax3 »

ALL indys (except the three actually used AT Indy) were 3.1 MPFI, only difference was 3-speed auto TH125C or 5-speed manual Getrag 282. The older MPFI engines are pretty stout on the top-end, and don't have LIMG failures like the SFI engines do, but they don't make the power the 3100 SFIs make at higher RPMs, though that encourages the driver to shift a little earlier for the MPFI's great mid-range torque, thus saving some gas there too.


1989 SuperCharged 3800 Srs-II (First)Six-Speed GTU
1990 Turbo 3.4 5-Speed T-Type
1990 4.0L 4-Cam 32-Valve V-8 5-Speed Indy GTi (Project)
1990 Stock(!) 3.1 MPFI Auto Indy
1995 LA1/L82 4T60E Z-26
1995 3.4 DOHC Turbo 5-Speed Z-26
Mkweaver1958
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Re: Any easy, cheaper ways to increase MPG?

Post by Mkweaver1958 »

Cam2363 wrote:
Mkweaver1958 wrote:My 90 Indy gets a steady 21.8 mpg with mixed driving. Best ever was 28 full highway trip.
Nice. What engine do you have?
Its a stock 3.1 with 146K on it.
To top it all off the Torque converter lock-up in not functioning, I guess if I fixed it the MPG would get a small bump in HWY mileage.


Cam2363
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Re: RE: Re: Any easy, cheaper ways to increase MPG?

Post by Cam2363 »

Mkweaver1958 wrote:
Cam2363 wrote:
Mkweaver1958 wrote:My 90 Indy gets a steady 21.8 mpg with mixed driving. Best ever was 28 full highway trip.
Nice. What engine do you have?
Its a stock 3.1 with 146K on it.
To top it all off the Torque converter lock-up in not functioning, I guess if I fixed it the MPG would get a small bump in HWY mileage.
Man. I think my mpg is so poor because I do mostly back road driving, not so much city. So its stopping and then getting back up to 40 or so every 2 or 3 minutes so that is probably what is killing my mpgs

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Cam2363
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Re: Any easy, cheaper ways to increase MPG?

Post by Cam2363 »

I got 14.55 on my last fill-up. I got 17 the time before. Really bad dip. Im going to be doing highway driving this weekend, so I will be eager to see how much of an improvement I get


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Re: Any easy, cheaper ways to increase MPG?

Post by 3X00-Modified »

You still shouldn't be seeing that low of MPG with that setup. If you're warming the car up in the winter then throw that MPG average out the window, you wont be able to improve upon that. I would suggest doing a standard tune up if you have not already, and with these aging cars, cleaning or replacing the injectors in my mind is part of a tune up now, in addition to that I see you've done plugs and wires, and perhaps cleaned the MAF sensor, but I would also suggest throwing a new O2 sensor at it. The upstream one is the one that controls the fueling, downstream only verifies the cat is operating as it should.


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Re: Any easy, cheaper ways to increase MPG?

Post by Cam2363 »

3X00-Modified wrote:You still shouldn't be seeing that low of MPG with that setup. If you're warming the car up in the winter then throw that MPG average out the window, you wont be able to improve upon that. I would suggest doing a standard tune up if you have not already, and with these aging cars, cleaning or replacing the injectors in my mind is part of a tune up now, in addition to that I see you've done plugs and wires, and perhaps cleaned the MAF sensor, but I would also suggest throwing a new O2 sensor at it. The upstream one is the one that controls the fueling, downstream only verifies the cat is operating as it should.
Alright. Replacing injectors seems really expensive, and not an option. I will try a new O2 sensor then. Ive clened the MAF, done plugs and wires, fuel filter, pcv, air filter, etc.

I normally dont warm it up as I had the garage in the winter, but even now, when I leave school I hit the button, so it runs for like 3 minutes max before I start driving it. I often sit idling while it warms up due to how long it takes to get out sometimes, so could that be it? Most days its about like 5 or 6 minutes of sitting there.


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Re: Any easy, cheaper ways to increase MPG?

Post by 3X00-Modified »

3 min and 5-6min of idling yes that will change your MPG immensely... I have a 07 Legacy GT with a dash readout and I can watch my average drop when I warm the car up for 5-10 min in the winter... That is why I invested in a block heater.

As far as changing injectors, don't rule that out when it comes to cost. You can get a set on eBay for around $60... Or you can spend a bit more on a potentially more reliable set priced at $118 for "new" vs refurbished.

Don't be cheap on repairs otherwise it will cost you more in the end... take some time and save up some money to do it right, the savings in gas will pay you back.


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Re: Any easy, cheaper ways to increase MPG?

Post by Cam2363 »

3X00-Modified wrote:3 min and 5-6min of idling yes that will change your MPG immensely... I have a 07 Legacy GT with a dash readout and I can watch my average drop when I warm the car up for 5-10 min in the winter... That is why I invested in a block heater.

As far as changing injectors, don't rule that out when it comes to cost. You can get a set on eBay for around $60... Or you can spend a bit more on a potentially more reliable set priced at $118 for "new" vs refurbished.

Don't be cheap on repairs otherwise it will cost you more in the end... take some time and save up some money to do it right, the savings in gas will pay you back.
Wow, I didnt realize that makes so much of a difference. It will be interesting to see if it improved in the summer when I dont have that idle time at school.

I will work on saving for some new injectors. Should I put a new FPR on too while I have it all apart?


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