Marauder w/SC Gas Milage Need Help

[thebeeper]

Hi folks:
Well , I "think" I finally got my 2004 MM with the SC to operate without overheating ( long story ) . Dennis Reinhart did a GREAT job on the installation , but what happened when I got the car back from Florida ( I live in Boulder City , Nevada where the temps get 100 to 110 during the summer ) , I had a overheating problem when the car was stopped at traffic lights . Make a long story a little shorter , ended up putting a large aluminum radiator in to compensate for the air flow blockage the intercooler was causing . Dennis Reinhart came thru with the new radiator !
Now my question to all of you , has anyone had a drastic gas milage loss after a SC install . Mine went from 22 MPG on the road to about 11 ! ! ! Just about half . I have not touched the tune in it from when it left Dennis's shop in Florida .
I have talked to Dennis Reinhart a few times on this , he has no idea of what to do . He said that he has done others producing more RWHP than mine , and getting up to 18 MPG on the road .
Any suggestions ?????????
Thanks in advance .
Dave

[CWright]

I'm still getting just over 20 mpg on HWY but around town is closer to 15 if I'm lucky! :D Hard to keep that foot back!:burnout:

[thebeeper]

Sounds great . Wish I could .
I am getting that 10 or 11 on the road just cruising at 60 to 70 MPH . I tried 2 tank fulls , without getting "into it" , or any highspeed chases !
In town , its about 9 .

[CWright]

What's your RPM's at 70?

[blazen71]

I'm getting 15 mpg combined and 18 hwy only.

[justbob]

Average 12-14 mix having fun and 23 1/2 hwy @ 75 MPH

To answer your question, my best ever stock was 21 1/2, then Trilogy 22 1/2, then aggressive tune, 23 1/2!!! Go figure.

Sent from my Ally using Tapatalk

[sailsmen]

In order for us to help you please help us by listing all your mods.

I just got back from a 1,000 mile road trip and averaged 19-20MPG.
Normal driving in the City/Suburbs 15MPG.

See my sig for mods.

If you give it any kind of acceleration the MPG goes way down.

If you are running super rich you can damage your engine.

[DOOM]

Are you driving the entire time with the o/d OFF???

[Paul]

I get between 13-15 mpg around town, depending on my driving style, and up to 19 highway. Sounds like you might be running too rich, could be any number of things - mechanical, sensor, tune.

[SC Cheesehead]

Are you driving the entire time with the o/d OFF???

That's what I was thinking. Mileage shouldn't vary much due to S/C installation, other than a MUCH heavier right foot after installation.

I averaged 21.5 highway, 17 in town NA, getting around 20.5 highway now, if I can keep my foot out of it.

In town is around 12, but that is TOTALLY my fault.... ;)

[Mr. Man]

Get a locking gas cap

[tbone]

I replaced my oxygen sensors at 129k miles and seem to have gone from 15 mpg around town to about 17/18 mpg.

[DEFYANT]

I've gotten 20mpg on road trips using cruise control and not getting into the boost. But forget MPG, whats up with the overheating? The stock radiator should have been plenty to keep it cool. Is your fan working?

[thebeeper]

Thanks for all the replies . I'll try to give some more info on what was happening then and now .
First , the RPM's at 70 are approx. 2150 . I still have the factory 3:25's in the rear .
Dennis installed the Novi 1500 , 3000 stall convertor , etc. .
Remember the car just came back from Florida ( Dennis Reinhart's shop that did the install ) . He checked out the program and dyno'd it , said everything was fine , does not know why the poor gas mileage , or how to remedy it) .

I also just got the car back from Bruce Tucker at JBA Performance in San Diego . He is a guru with supercharged motors ( Mustangs , Marauders , etc. ) . By the way , a AWESOME person to work with wth supercharged motors. He data logged the car for quite a long time , and suggested the aluminum radiator which I bought from Dennis Reinhart . The overheating problem we believe was lack of air flow . On a 105 degree day with only 5 percent humidity out here in Nevada , if the car sat at idle , in gear , A/C on , for any more than 15 minutes , it got up to 260 to 270 degrees . At that point , if you took the car on the road and did over 25 MPH , the temp would come right down to 210 .
Now with the aluminum radiator , it "seems" to have corrected the overheating . Car runs about 190 on the interstate , and when it was 108 in air temp out here , car in traffic was at about 215 . That would be about normal for this climate in the hot summer .
Gas mileage has not changed since I got it back from Dennis's shop . City t highway only lends me another 2 or 3 miles to the gallon . Tops out at 11 or 12 at best on the highway at a steady 65 to 70 MPH .
Excatly what the specs are on all items installed along with the SC , Dennis would have a spec sheet . He did a great job on the install , car runs out great , not a problem there .
Hope I have not bored too many of you with all the info .
Dave

[sailsmen]

Do a test on a tank of gas by doing your best to get the best gas mileage. If you can't get 14 in the city then get your car back on the Dyno and check the AFR.

How much ethanol is in the gas?

If it is running super rich you will end up with a new engine.

As respects the high temps a bigger rad does not increase air flow. It may allow more air flow or dissipate more heat. Did you try flipping the OEM fan shroud like the ProCharger or do you have the Mustang open fan shroud?

[TFB]

A/F ratio will have to be extremely rich to drop mileage that low, a tuner should be able to determine the problem fairly easily...

Like most of the others, mine gets 21-22mpg on the highway...

[RF Overlord]

Never really paid a lot of attention, but coming back from Lidio's after the Trilogy install we got approx 21 MPG on the highway at 75 MPH (mostly) with two of us and luggage for a week in the car.

Not trying to add insult to injury, but just giving you as many examples of MPG of blower cars...11 MPG is WAY off

[blazen71]

As respects the high temps a bigger rad does not increase air flow. It may allow more air flow or dissipate more heat. Did you try flipping the OEM fan shroud like the ProCharger or do you have the Mustang open fan shroud?

I'm pretty sure Dennis uses a mustang fan/shroud. I've heard from other members the mustang shroud isn't as good as the flipped Marauder shroud in really hot temps. FWIW I flipped mine and works great.

[thebeeper]

Hey Sailsmen
To answer a couple of your questions concerning my poor gas mileage :
When the car was checked out in San Diego by Bruce Tucker at JBA Performance , that was the first thing he checked for , a “rich” mixture at both idle , and on the road . The fuel trims were set perfect .
I believe the ethanol percentage here in Nevada is 5 to 10% .

The reason for the larger radiator was strictly to make up for the air flow blockage that the intercooler was causing . The intercooler was blocking off the lower portion of the stock radiator . If the car was in a little cooler climate , there would not be a problem . Out here , once you were traveling on the road , the temp was fine . Stopped in traffic, with 110 degrees out , 55 humidity , and 160 degrees coming off the pavement , and 200 degree heat coming from the car in front of you , and blocking off some of the radiator , it would start to climb on the temp . I think you understand now . Dennis had put on the Mustang design fan which did not have a shroud . What I ended up doing was buying a new setup with TWO fans already mounted in a shroud . Worked out great size wise and more CFM’s being sucked in that the Mustang setup .
Dave

[thebeeper]

Hey Sailsmen:
Here is another fact the might be "some" of the reason , just maybe ........the car does not have th origianl motor , it has a brand new crate COBRA 4.6 motor installed , and I only hve approx. 2500 miles on it . Maybe when it gets a few more miles on it , gas mileage "might" improve a little .

[sailsmen]

I had the same condition and provided the info for the fans for you;
Flexilite 480/490 twin fans, 12"DUAL X-TREME DUAL PUSH.

Did you install the bigger rad after the Flexilite twin fans?

Either the fuel is going in your engine as in it is running rich or it is leaking before the engine. Either way something is wrong and you need to get it fixed.

[thebeeper]

Sailsmen
YES , that is the fan setup I used , I believe it was the 480. It had the duel fans with shroud . I first installed the fan setup , helped some , then the larger Griffin aluminum radiator . Helped even more . Agin this was strickly for the overheating problem . Nothing to do with the poor gas mileage .

Both Dennis Reinhart and Bruce Tucker from JBA Performance checked it out for too rich of a fuel mixture ( from idle to full throttle ) , both said the AF ratio was set perfect .
Dave

[GordonB]

Dave/thebeeper,
You said you are in Nevada. What is your altitude? Is there a 'thin air / altitude problem' here? What was the usual mileage BEFORE S/C install? Just a thought. Had a friend in Denver who used to talk about lousy mileage in that high altitude climate. He came East to Maryland and pboblem went away. But ... with electronic/computer calibrated engines these days altitude should NOT be a big problem. Just a tought.
GordonB

[sailsmen]

Sailsmen
YES , that is the fan setup I used , I believe it was the 480. It had the duel fans with shroud . I first installed the fan setup , helped some , then the larger Griffin aluminum radiator . Helped even more . Agin this was strickly for the overheating problem . Nothing to do with the poor gas mileage .

Both Dennis Reinhart and Bruce Tucker from JBA Performance checked it out for too rich of a fuel mixture ( from idle to full throttle ) , both said the AF ratio was set perfect .
Dave

Either the gas is going in the engine or it is leaking.

What is the max boost? Can you post your Dyno Graph?

[thebeeper]

The altitude here in Boulder City Nevada is 2600 ft. .
Bruce Tucker @ JBA said altitude would not be a problem until you got in the 7000 to 9000 ft range ( like Flagstaff AZ ) . I know the car manufacturers come out here to Boulder City , and the surrounding area to set their new cars up to go back to the facotry ( we get to see alot of the new and FX cars before they hit the production lines ) .
Dennis Reinhart has the dyno charts from his runs . He has it set at only 6 lb. boost . Car had a RWHP of only 440 I believe .
My original mileage ( remember , that would be wen I had the original motor in it , not this crate COBRA motor ) , from the start was approx. 18 to 20 on the road , then when I had 10,000 miles on the motor I was getting about 22 to 23 on the road , and 17 to 18 in the city . Again , thats with the original motor .

Dave

[steve fox]

440rwhp with 6 lbs boost? seems like a lot. The stock 4.6 with 15 lbs boost averages less than 400

[Dennis Reinhart]

The Stft were checked by Bruce at JBA he said the were perfect the car was tuned at sea level Dave is way up there a dyno tune there may help

[JoeBoomz]

440rwhp with 6 lbs boost? seems like a lot. The stock 4.6 with 15 lbs boost averages less than 400
Depends on the blower.

Beeper, are you certain there is no fuel leak somewhere along the line, perhaps around the fuel filter?

[thebeeper]

The SC that was put in is a NOVI 1500 . Air to air intercooler .
No , there is absoutly no fuel leaks anywhere . The car is always kept in a secure garage , with no signs what-so-ever of any leaks with fuel .

[sailsmen]

If it is not leaking it is going in the engine. Try driving to get the best mileage possible for a tankfull and report back.

[Vortech347]

Get a wideband on that thing ASAP. It could be running so damn rich you're washing the cylinder walls down.

[Dennis Reinhart]

Get a wideband on that thing ASAP. It could be running so damn rich you're washing the cylinder walls down.

It's not running rich the fuel trims are perfect

[Vortech347]

It's not running rich the fuel trims are perfect

While I'm a big fan of data logging I've had a log say one thing, and the wide band say another. There could be a mechanical issue with one or more of the injectors.

Another thing I'd recommend is to pull the plugs and take a look at them.

If he's getting 11mpg its simple. Either the fuel tank is leaking, or the fuel is going into the chamber, or someone is stealing his gas at night.

[Dennis Reinhart]

If a injector was leaking the fuel trims would be way off on one bank, the car was checked at JBA by Bruce who is one of the top tuners in Ca and he said the tune was dead nuts on but David was short on time and did not get a chance to have Bruce put it on the dyno. I feel with the altitude difference the car should be checked out there. And Bruce has a impeccable reputation and is the best around on that coast.

[Motorhead350]

Your car needs a tune.

[thebeeper]

Just a added correction to one of my previous posts , and also another bit of info .
FIRST , I was in error about the boost produced . I had stated it was 5 or 6 lbs. . The 440 RWHP that is produced is with 11 lbs boost . Sorry for the info error .

Now , second thing .....because a couple of people mentioned this ......I had 4 spark plusg taken out to check for running rich ( two from each side ) . All were a really nice very light tan color . Perfect burn color . Not rich , and not lean .

Dave

[sailsmen]

I previously posted run a tank full while trying to get the best mileage possible and report back.
You have apparently eliminated a leak, theft, running rich so the last one is your heavy foot.

Whenever I drove mine in a "spirited" fashion I didn't even bother to record MPG. An S/C does not majically make power. IT puts more air in the engine which allows more fuel, get it more fuel.

[Bradley G]

Well I suppose we have determined that indeed nothing is malfunctioning with the car, the OP is most certainly appears to be getting his monies worth.:D