LUV94RX7

iTrader: (3)

I was wondering why the gas economy was so good. The car has a real-time A/F monitor and it was in the plus 14's while cruising at 80-90mph. I'm sure that had a lot to do with the good mpg. I still can't believe a gas hog like a rotary could get 20+mpg with a souped-up motor with a T66 turbo. It has Datalogit and the air temps were around 47-50C and the water temps were 203-207C. When they got to 207C I slowed down to get it back to 203C. It was really hot in TX(100+ at the end of the trip).

The following is a small except from a post I have in the Lounge on a trip I made a couple of days ago. Also there is interesting info on me getting screwed by the State of Georgia.

https://www.rx7club.com/lounge-192/pluses-minuses-my-trip-picking-up-cover8%92s-car-447846/

"The Pluses and Minuses of My trip Picking Up Cover8’s Car

I flew to Florence, SC to pick up COVER8's car.

I drove non-stop to Gotham Racing where I dropped the car off and flew back to MN. Steve will be doing some work on it including tuning.

The car ran flawlessly.

On two legs of the trip I was going 90+mph whenever the traffic allowed. I averaged 81mph on one 306-mile leg with AC off and I got 20.4mpg and about a 1/3 of the way I had it in 4th gear by mistake. On the other leg with AC on I averaged 78mph for 277 miles and got 19.2 mpg. I thought this was unbelievable MPG for going so fast with a souped up FD with a T66 turbo and me with a lead foot. At end of the trip I needed 1 qt of oil and 1/2 of the water was used in the water reserve for water injection.

It got really hot at the end in Texas, 100+ degrees.
Thanks to Nick for getting the AC recharged. In that terrible heat I thought I'd have a heat stroke. AC in RX-7's are not very good but I would have died without it."

So can I expect to get that kind of MPG after I upgrade my motor with a T66 and Kan rebuilds it and tunes it?

Thanx,

DaleClark

iTrader: (55)

In general, the mods on a car don't affect highway cruising MPG that much. MPG is kind of set by the volume of air the engine sucks in and how much fuel you have to squirt into it - the size of the turbo, the intercooler, etc. doesn't really come into effect. Porting can effect MPG, since you increase the quantity of air pumped through the engine.

Anyhow, glad to hear your trip went well!

Dale

rotorbrain

those are pretty high water temps you have listed there. . . you sure youre not talking about fahrenheit (sp?)? i normally see more than 100 degrees celcuis LOWER!!!!!

thats quite an achievement when it comes to mpg!!! im interested in know what the timing maps look like AND whether the engine is ported or not.

paul

LUV94RX7

iTrader: (3)

Sorry my mistake:
"the water temps were 203-207C. When they got to 207C I slowed down to get it back to 203C."

Those should be 103-107C NOT 203-207C.

Ken

cloead

That's still really hot.. my car runs at 87 degrees celcius and hits about 89C after a lot of WOT. Probably has something to do with the 100 degree texas heat or something.

LUV94RX7

iTrader: (3)

90+mph and AC on with FMIC and 100+F on a hot freewany in TX. I cut speed to 75mph and water dropped to 103C from 107C. It was really hot that day. I'm used to MN weather.

Ken

PhoenixDownVII

For those that care to know, thats going from 224F down to 217F.

I don't like seeing 210F on my car let alone 224F *Gasp*

I know you were in possibly the worst condition possible but is that really safe? I wonder what other cars run in such extreme heat...

Force13B

iTrader: (19)

Sounds like a cool trip, I've gotten 21.3mpg on the freeway before. Stock engine HKS down, and 3 in cat back. I was also doing about 80.

LUV94RX7

iTrader: (3)

Well my other car has Evans NPG+ so I never really look at the temps much and we never get 100F days in MN, well maybe once every decade.

When I was cruising along at 90mph and AC on and it was 103C I turned AC off for about 10 miles and it only dropped to 102C so I put the AC back on and slowed down to 75mph as I was dying from the heat.

Ken

PhoenixDownVII

My A/C blows colder than any other car I've driven. However, it's an R-12 Recent recharge. Was that one updated or serviced recently?

Also, does the car have a fan switch, or were your fans only on when the A/C was blasting...

David Beale

I've gotten 9.5 L/100km - perhaps a little better than what you were getting? That's at a much lower speed, on a very curvey road, with up to 18% grades, so accellerating and slowing constantly (playing). I have stock twins, PFC and basically open exhaust (HKS Superdragger cat back with no cats in front and a downpipe). On the highway at 80 MPH I get 10 L/100Km.

I have no idea what temps. I would run with ambient at 100+F - thankfully we don't see that kind of temps. At an ambient of 85-90 F I was running 93C coolant temps on the PFC Commander readout - at 120 - 130 km/hr or just under 80 MPH.

I don't think those high coolant temps. would hurt anything, as long as they are stable. That is to say, as long as you don't get into boiling episodes.

LUV94RX7

iTrader: (3)

I picked the car up in SC at 2:30am and drove non-stop to TX. He recharged the AC that day for me. Don't know anything else about R-12 or fan switch and whether they were on or off. It has a Greddy FMIC. I just drove and filled the gas tank when needed.

Ken

Swolbynos

i just got my car back from gotham, and got 23.5 MPG coming home with a half bridge and the GR67 turbo kit

LUV94RX7

iTrader: (3)

Well my other car has Evans NPG+ so I never really look at the temps much and we never get 100F days in MN, well maybe once every decade.

When I was cruising along at 90mph and AC on and it was 103C I turned AC off for about 10 miles and it only dropped to 102C so I put the AC back on and slowed down to 75mph as I was dying from the heat.

Ken

GoodfellaFD3S

iTrader: (213)

I have seen as high as 22 mpg on cross country trips.

I drove my car for years in texas and my water temps were almost always below 100. Hell, last time I roadraced at Motorsport Ranch my *peak* water temps were 99, and this was at 1 bar boost in September. Of course, I had a/c and p/s removed, among other things. 103-107 is too hot, check your coolant mixture and purge the system of any air pockets.

coolvette

i got over 27 mpg on stock tire and rims.It has dropped to 25.4 with my new 18s. maybe it will go back up when i install my hiflo cat and twinpower.