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Triumph TR6 - Poor Gas Mileage

While others seem to be getting around 20-28 mpg, I seem to only get about 12 mpg in the city.
I rebuilt my carbs, and checked for any leakage from the tank and the fuel system. The poor mileage started when I removed the EGR system, and took off the vacuum retard (which I understand should not affect it, if anything should improve power and effeciency.

While the car runs beautifully except when cold on start up when it is a bit lumpy, I find it hard that a 2.5L motor uses so much gas, might as well drive a good old American muscle car if I am burning that much...at least then I have 300+HP on tap. I do notice that I seem to have a choke problem as I never can pull it all the way out without stalling the engine or having serious mis-firing / laboured idle.

Any suggestions?

Done:
New Plugs, wires
New Rotor, points, cap (dist was rebuilt)
Timing is 18*BTDC
Valves adjusted
Carbs rebuilt with gross jets

steven

Steven--Your timing seems excessively advanced; is your idle timing measurement off the crank dampner scale?
Rick Orthen

I have a copy of an article that on the EGR written by some Lee Janssen that I got off Zimmerman's web page (does anybody know if this has been resurrected anywhere?) that I can send you or anybody else via email if you want to read it (3 short pages). The bottom line of this article was that although you may increase power by removing the EGR since you will have a cleaner air/fuel mix, the unburnt fuel that is not recovered by the EGR is lost, thus you have a drop in mileage. The article did not say whether this drop is significant or not. For all I know it could be less than 0.001 mpg.

After rebuilding my carbs, tuning, etc. I am now getting about 16-18 mpg of purely city driving from an all stock 74 without OD. Most of my emmissions BS is still intact, except for that stupid connection between the EGR and the choke that I mentioned in another thread. I would be interested in knowing what others get from mostly city driving.
Ignatius

In those thrilling days of yesteryear when I used my TR6 as a daily driver and in stock tune, I would get about 20 mpg in a mix of surface street traffic and freeway driving. Just guesstimating, if the freeway driving were taken out of the mix, then 16-18 would probably be about what I was getting in the normal stop and slog stuff. That was in Texas miles, if you want it in either L/Km or Km/L, you'll have to crunch the numbers yourself. I'm not going down that dirtpath this time around.

Steve "Stay away from them metric miles boy....they'll just get you into trouble" P
SteveP

Steven: My 72 runs around 15 to 16 in the city. Highway is about 25. Seems to run well and I haven't found any puddles on the garage floor.
Joel

My '74 also get around 12-16 miles per gallon. I do pretty much all city driving to and from work, and the occasional 40-50 mile trip. My mechanic New Orleans told me the car sounded as if it had a 'hot' cam in it. I have no reason to doubt my old mechanic, haven't been able to confirm this with the previous owner. How much would that affect my mileage?
Jeff
Jeff hall

Now that I think about it, my mileage numbers are probably inflated 10% since I have smaller tires than usual (195/60). ...so I am probably really only getting 14-16 mpg.
Ignatius

Rick: my timing is with a light off of the crank pully

Not to get back to the metric vs imperial system but rather real imperial vs American system, my MPG calculations is based on an imperial gallon which is 20% larger than a US one. With this in mind my car would be getting 10mpg on a US Gallon.

I can't help but think that it is exceessive for a 2.5L engine that is not hopped up, putting out a whopping 106hp
steven

Gentlemen. I don't know why a TR6 with a 6-cylinder 2.5 litre engine should get such low gas mileage, but maybe you all drive harder than I do.

Let me share with you the results of my recent trip to VTR in Red Wing Minnesota with my 4-cylinder TR3A with 67,000 miles on the engine since my last re-build 12 summers ago. The engine is stock (1991 cc displacement) and the cam has never been out the block. I still have the original tappets, push-rods, rockers and rocker arm. The total mileage on the car is 147,000 miles. My coil is the one that came with the car in 1958. I put in new points and condenser before I left home.

I drove my TR3A 2916 miles in 11 days. Montreal, Ottawa, Sudbury, Sault Ste. Marie, No. Mich. across Wisc. (#64) then south to Red Wing (#63). After the show, I drove to Milwaukee and home via Green Bay and the return route was the same as going down. About 600 miles was on 4-lane limited access or Freeways. The rest was on 2-lane rural or secondary roads.

My rolling average speed with overdrive was 67 miles per hour.

My fuel consumption was 33.4 miles per Imperial gallon (27.8 miles per US gal). I know there was very little "city driving", but I wind it up to 5000 rpm almost every time.

I have never timed my engine with a strobe. I advance the distributor bit by bit till it starts "pinking", then I back it off a touch. I run with 91 octane but in the US, I was able to find 92 and 93 octane.

Once a year, I tune my carbs with a hose to listen to the hiss. Last year I drove over 10,000 miles and so far this year, over 5700 miles.

I took 4th in my class (out of 5) in the autocross at VTR and 2nd in my concours class with 383 points out of 400 (the winner and best of show got 388 points).

So I think all you TR6 owners should keep on trying to find out why your gas mileage is so low.

Don Elliott, Original Owner, 1958 TR3A

Don Elliott

1 litre = .22 Imp gallons.
A 25 litre fillup = 5.5 gallons.
5.5 gallons = average 135 miles (mix highway and city)
1 gallon gets 24.5 miles
Botton line = it costs me twice as much to drive Toronto to Kingston as my Honda Civic ($20 instead of $10).
Yes, she's a greedy little sausage when it comes to gas.
Bryn

Gee, with mine sitting in the garage the last couple of years the gas mileage is incredable.
DON KELLY

Hi guys,
Here's my mileage info,
TR6 with a "Big American" 5.0 litre engine,
total weight 2500lbs, 300+ HP on tap,
21 miles per Imp. gallon.
Not that I'm biased or anything, but...
just one more reason to pull that old tractor
engine out.
Christopher Trace

This thread was discussed between 17/07/2002 and 19/08/2002

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