250hp gas mileage
12-19-04, 10:04 AM
#1
Mechanical Engineering
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250hp gas mileage
hey all
i see what mods and how much hp people have around here but not alot about what thier gas mileage is. what kinda of gas mileage are you guys and gals getting around here? what mods? power?
i see what mods and how much hp people have around here but not alot about what thier gas mileage is. what kinda of gas mileage are you guys and gals getting around here? what mods? power?
12-19-04, 10:27 AM
#2
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If the car is set up properly, then mileage should be uneffected unless the driver is always at WOT.
There's no reason for a 250HP rotary to burn more fuel at cruise and light load then the stock engine.
There's no reason for a 250HP rotary to burn more fuel at cruise and light load then the stock engine.
12-19-04, 10:54 AM
#4
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There are probably a lot of 2nd gens out there that are NOT running properly. Any amount of reading through this forum should show how many cars are hacked to death, running like crap, etc. 
12-19-04, 11:14 AM
#6
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if i hold my 88TII around 60ish, i can manage 21mpg or so. but that can quickly fade to 15mpg if i get boost happy. oh, i'm prolly looking at around 280 at the fly.
12-19-04, 11:24 AM
#7
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It all depends on how you are making 250hp. Peak hp doesn't really act as a basis for fuel consumption.
There are really two factors that you are looking at:
1) Power Required
a) Vehicle Coefficient of Drag
b) Tire Coefficient of Friction
c) Acceleration Rate
d) Vehicle Weight
e) Vehicle Speed
f) Road Surface (Friction and Grade)
g) Weather Conditions (Wind, Temperature, Barometer)
2) Power Produced
a) Brake Specific Fuel Consumption (fuel consumption per hp)
b) Drive Train Loss
There are really two factors that you are looking at:
1) Power Required
a) Vehicle Coefficient of Drag
b) Tire Coefficient of Friction
c) Acceleration Rate
d) Vehicle Weight
e) Vehicle Speed
f) Road Surface (Friction and Grade)
g) Weather Conditions (Wind, Temperature, Barometer)
2) Power Produced
a) Brake Specific Fuel Consumption (fuel consumption per hp)
b) Drive Train Loss
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12-19-04, 11:39 AM
#8
Mechanical Engineering
Thread Starter
well then lets say 250 at the crank so roughly 220 at the wheels stock turbo new exhaust (for all purposes RB) new filter, stock wheels and upgraded pump and injectors, that would roughly make 250 right?
12-19-04, 11:52 AM
#9
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like he just said, peak power is irrelevant for gas mileage. you aren't making peak power at cruise. i know of two people who were making over 400whp that claimed getting around mid-20mpg; big turbo, haltech, highway miles.
12-19-04, 12:31 PM
#10
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Originally Posted by capn
well then lets say 250 at the crank so roughly 220 at the wheels stock turbo new exhaust (for all purposes RB) new filter, stock wheels and upgraded pump and injectors, that would roughly make 250 right?
https://www.rx7club.com/attachment.p...chmentid=79705
12-19-04, 12:48 PM
#11
Mechanical Engineering
Thread Starter
ok, i undserstand that it wont make peak hp all the time, so if it was tuned right it could get decent gas mileage, so would it be best to run a standalone or would the stock ECU be able to handle it and be reliable at it?
12-19-04, 01:14 PM
#12
I've got a nice amount of power and I get pretty damn good gas mileage (unles boosting all the time) until the last quarter of a tank for some reason and then it just kinda goes down really quickly but other than that it has about the same gas milage as my honda passport (94 v6).
12-19-04, 01:15 PM
#13
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the stock ecu should have no problems handling it, i'm still using the stock one. i need to get an SAFC to maximize my peak power but as long as the car is cruising, the stock ecu works.
12-19-04, 03:36 PM
#14
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Originally Posted by capn
ok, i undserstand that it wont make peak hp all the time, so if it was tuned right it could get decent gas mileage, so would it be best to run a standalone or would the stock ECU be able to handle it and be reliable at it?
12-19-04, 05:51 PM
#15
Mechanical Engineering
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i was thinking turbo
Originally Posted by Evil Aviator
Yes, if you spend $1,000 to 2,000 on a standalone EMS, plus $500-3,000 for installation and tuning, a professional can tweak the engine to get better gas mileage than stock, assuming that the engine is newly rebuilt and has all new (or like new) components. The question is whether or not it is worth all that money to get better fuel economy. If your "250hp" engine is a non-turbo engine and gets the bulk of its horspower increase from porting, then you may or may not get better fuel economy.
12-19-04, 05:57 PM
#16
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With turbo cars that don't have radical porting, there's no reason they should be getting pathetic mileage. As long as things are set up properly. Running 1000 CC primary injectors on the stock ECU while the car is trailing black smoke and unburned fuel will result in crappy mileage. Properly setting things up is important. Run those same 1000CC injectors in the secondary position, and then use an S-AFC to trim off excess fuel, and you should have factory (or better!) mileage when you stay off the boost.
Aftermarket ECUs that are properly tuned will generally give you better mileage numbers, but you either need to know how to tune them, or pay someone else to do so.
Aftermarket ECUs that are properly tuned will generally give you better mileage numbers, but you either need to know how to tune them, or pay someone else to do so.
12-19-04, 09:20 PM
#17
Mechanical Engineering
Thread Starter
well hows your gas mileage? i mean doesnt the NA turbo deal spool up pretty fast so your almost always in boost?
Originally Posted by Aaron Cake
With turbo cars that don't have radical porting, there's no reason they should be getting pathetic mileage. As long as things are set up properly. Running 1000 CC primary injectors on the stock ECU while the car is trailing black smoke and unburned fuel will result in crappy mileage. Properly setting things up is important. Run those same 1000CC injectors in the secondary position, and then use an S-AFC to trim off excess fuel, and you should have factory (or better!) mileage when you stay off the boost.
Aftermarket ECUs that are properly tuned will generally give you better mileage numbers, but you either need to know how to tune them, or pay someone else to do so.
Aftermarket ECUs that are properly tuned will generally give you better mileage numbers, but you either need to know how to tune them, or pay someone else to do so.
12-20-04, 10:13 AM
#18
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With my original setup (turbo, stock ECU, S-AFC) one tuned my normal driving mileage was better then the stock setup. If I was on the highway, in some cases the S-AFC could go into the high throttle map, which made the mileage suck (quarter range TPS is to blame). I didn't have the "always in boost on the highway" problem.
New setup is not put together yet.
New setup is not put together yet.
12-20-04, 05:51 PM
#19
Mechanical Engineering
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will your new setup have better gas mileage? or at least decent gas mileage? also with the new system your running is it possible to switch to mild to wild like what your safc did with the high throttle map deal?
Originally Posted by Aaron Cake
With my original setup (turbo, stock ECU, S-AFC) one tuned my normal driving mileage was better then the stock setup. If I was on the highway, in some cases the S-AFC could go into the high throttle map, which made the mileage suck (quarter range TPS is to blame). I didn't have the "always in boost on the highway" problem.
New setup is not put together yet.
New setup is not put together yet.
12-20-04, 06:16 PM
#20
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welp, i have a N/A engine with turbo & it spools up around 2k rpms. so yea you can say ur always spooling. but you dont have to worry if ur driving at a low boost(psi). i stay on 6lbs of boost all the time.
12-20-04, 06:25 PM
#21
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If you're porting to achieve the power (likely on an NA) the fuel economy will likely suffer, unless you only port ports that are closed @ idle, light load, and cruise (aux ports for example with a functioning 6pi system).
12-20-04, 07:43 PM
#22
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Originally Posted by pengarufoo
If you're porting to achieve the power (likely on an NA) the fuel economy will likely suffer, unless you only port ports that are closed @ idle, light load, and cruise (aux ports for example with a functioning 6pi system).
i have an s5 n/a with mild port and open and cleaned 5th/6th ports and i managed 20.4mpg once. that was with a lot of highway miles with an air correction of -10% to -18% cruising between 2200 and 2800rpm. i think i still have a sensor out of wack and have a bucking issue and smoke at higher rpm WOT.
cars making 200+whp more than me can manage better gas mileage than i got. of course, i'm referring to highway miles.
12-20-04, 08:44 PM
#24
Mechanical Engineering
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thats why i said turbo, i know that if i would go with NA it would be too much trouble thus turbo. so i just want to know like peak 250 at WOT with decent gas mileage not all out racecar where it has 250 at idle
12-21-04, 10:27 AM
#25
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Originally Posted by capn
will your new setup have better gas mileage? or at least decent gas mileage? also with the new system your running is it possible to switch to mild to wild like what your safc did with the high throttle map deal?
There is no reason to switch from "mild to wild". A 900 HP 13B will use the same amont of fuel cruising at 60 MPH that a 140 HP 13B will (all things being equal, and ignoring porting).