rx7 460s = bad gas mileage?
#1
Former Vendor
Thread Starter
iTrader: (9)
Join Date: Jan 2008
Location: Bay Area, California
Posts: 929
Total Cats: 9
rx7 460s = bad gas mileage?
I've noticed a drop in gas mileage since installation of my rx7 460s yet I've got it tuned for mid 15 afrs while cruising, just like with the oem 1.6 injectors.
Anyone else notice a difference? Could it be because you don't have as much resolution with the bigger injectors?
Anyone else notice a difference? Could it be because you don't have as much resolution with the bigger injectors?
#2
with my 460's I get about 28mpg highway, haven't figured out my average combined mileage though. I got my highway calculation on an extended higway trip back from Deals Gap to my home in MD, near constant 80mph cruise (not on cruise control), split between 2 drivers, with one highway pull against a 350z. Seems like a decent representation to me.
I'm sure I'd get better mileage at 60mph or so, but I say 28mpg.
As for around town driving, it seems to get rather bad mileage. I think that it's a function of my heavy foot though!
I'm sure I'd get better mileage at 60mph or so, but I say 28mpg.
As for around town driving, it seems to get rather bad mileage. I think that it's a function of my heavy foot though!
#3
Elite Member
iTrader: (21)
Join Date: Jun 2006
Location: Point Pleasant, NJ
Posts: 2,957
Total Cats: 2
run HiRes.
Tune better.
Try using a lower required fuel number, and then raising your VE cell values by the inverse of that.(like JoePerez did, or was it AbeFM?) That will give you more res.
I've been too busy to tune mine well since turbo and I've been changing setups regularly but I still get 26-27mpg on my 460s during regular combined highway/around town driving. i have a heavy foot also
Tune better.
Try using a lower required fuel number, and then raising your VE cell values by the inverse of that.(like JoePerez did, or was it AbeFM?) That will give you more res.
I've been too busy to tune mine well since turbo and I've been changing setups regularly but I still get 26-27mpg on my 460s during regular combined highway/around town driving. i have a heavy foot also
#13
Before turbo with 460's I got like 22 mpg. Now that I got a turbo it seems to have gone up, yesterday the fuel needle(I know not very accurate) was at the middle mark and the car did 124 miles.
Ill know the exact improvement after I fill up.
I tune for 12:1 in boost, and 14.7 in cruise.
P.S. When I first installed the turbo, it was like 10:1 in boost if not even worse, and I went through like 6 gallons of gas in less then 70 miles.
Ill know the exact improvement after I fill up.
I tune for 12:1 in boost, and 14.7 in cruise.
P.S. When I first installed the turbo, it was like 10:1 in boost if not even worse, and I went through like 6 gallons of gas in less then 70 miles.
#14
Elite Member
iTrader: (21)
Join Date: Jun 2006
Location: Point Pleasant, NJ
Posts: 2,957
Total Cats: 2
i typically see ~160-170 when i hit the middle mark. after that if falls more rapidly.
Accel/decel enrichments can play a huge role in fuel consumption. Have you messed with those?
I cruise around 16afr and in decel it goes off the gauge. No reason to be throwing fuel in there when you are dragging.
Tune your idle manually. Set VE Analyzer(if you use it) to a min rpm of like 1800 so it doesn't screw with idle fueling. If you let your car warm up before taking her out(as you should) you could be wasting a lot of fuel during that time if your warmup enrichments are too high.
I love using VE Analyzer but after I've gotten a decent tune with it I manually adjust my cruise cells to bring it to around 16 afr.
Accel/decel enrichments can play a huge role in fuel consumption. Have you messed with those?
I cruise around 16afr and in decel it goes off the gauge. No reason to be throwing fuel in there when you are dragging.
Tune your idle manually. Set VE Analyzer(if you use it) to a min rpm of like 1800 so it doesn't screw with idle fueling. If you let your car warm up before taking her out(as you should) you could be wasting a lot of fuel during that time if your warmup enrichments are too high.
I love using VE Analyzer but after I've gotten a decent tune with it I manually adjust my cruise cells to bring it to around 16 afr.
#16
Boost Czar
iTrader: (62)
Join Date: May 2005
Location: Chantilly, VA
Posts: 79,494
Total Cats: 4,080
wait?! are you trying to say that if I figure you have (4) 460cc injectors, so that's 175 lbs/hr. If I multiple that by .80 (duty cycle) and divide by .55 (BFSC), I can see how much B.H.P. the pump is capable of flowing for?!?!?! so like, 254BHP at 47.5psi of fuel?! Insane!
#17
Boost Pope
iTrader: (8)
Join Date: Sep 2005
Location: Chicago. (The less-murder part.)
Posts: 33,027
Total Cats: 6,593
crashnscar, the mod Paul refers to is that I set my ReqFuel constant to 3.5ms, since according to [url=http://www.msextra.com/manuals/MS_Extra_Software_Manual.htm#hrcode]The Documentation[/u], this is exactly 100 times the native resolution of the HR code (35μs) and thus, each single digit increment in the VE table directly correlates to one whole step of the smallest possible change in fuel.
If your ReqFuel was, say 7ms, then the fuel would only actually change once every two VE digits. Ie: from 50 to 51 = no change, then from 51 to 52 = a change...
It results in a bizarre looking VE table, but for injectors in the 440-460 range at normal street-ish levels of boost, it means that we are able to use very nearly the entire 8 bit resolution of the VE variable. Here's an example:
But I hear you on fuel economy. After I switched to MS (the 465s had been in for a while previously) my economy went to ****. We're talking 19 MPG in town. Over time as I refined my VE table, enabled overrun cut, stopped wasting so much fuel cranking and ASE, leaned my idle back out to ~14.5, and so on, it's improved. Currently, I'm back to 22-24 MPG city (which is typical for my driving) and on a recent trip to LA and back I got over 29.
Thread
Thread Starter
Forum
Replies
Last Post