Who has fastest stock C-170B

[kmisegades]

Folks, I really enjoy my '52 C-170B, but I sure wish I could go 10-20 knots faster sometimes. It is clean, but without wheel pants and with 4" bugeye PAX window (wife enjoys photography), and has usual exhaust stack mod. Otherwise no external mods affecting aerodynamics and it has the original engine, very smoooooth. Who claims the fastest C-145 powered C-170B, and how did ya doit? I know, I know, why would anyone want to go faster in a C-170? Thanks in advance.
P.S. M-20 air/oil separator has done wonders for my belly. Use very little oil.

[dunlaps3]

I'm not sure I have the fastest , but mine will cruise at 135 MPH . I don't even know what wide open straight and level is ( I'll check that sometime soon ). I can't think of anything special that I did to it to make it so fast , with the exception of it says " FRANKLIN " on my engine. Andrew

[R COLLINS]

Kent,

Why did you exclude the A models, Ya scared

[GAHorn]

Look out, Kent!
Bein' new to this pond, you might need to be warned there's some sharks in these waters!
There's a green 170A here who claims to have seen 160 indicated once. (Not sure if the green is from envy of B-models, or airsickness. Despite the pull-out, He still claims his wings are flat too!)

What exhaust stack mod do you have? Benham? Bartone? Other?

[kmisegades]

Thanks for the quick response, folks:

Andrew - what does the Franklin put out? What has your experience been with it, maintenance and fuel burn-wise? Former Franklin owners I know either love it or hate it, no middle ground. Is yours an original, or from the new production from eastern Europe I think?

R Collins - no offense. I suspect that the 170s and 170As are faster anyway as these things often go with maturing planes.

Gahorn - not sure on the stack mods but will check the logbooks. Stacks moved up behind cowl, two holes closed in the lower cowl, new stacks exit just upstream of firewall, very clean setup.

All - there was a fellow out in the midwest a few years back who made numerous aero and engine mods to a Piper PA-20 Pacer, adding 20+ kts to speed. Surely a stock Pacer is no better than a stock C-170, thus my optimism that one might be able to improve the 170s speed. I am an aero guy which perhaps explains my fetish.

[GAHorn]

A 170 (any model) supposedly makes about 104 knots at cruise, standard equipment.
The after-market speed brakes advertised for high performance singles have only a few square inches of area to present with the speed brakes deployed, and they advertise fairly large speed reduction capability. This makes it pretty dramatically evident that drag does indeed increase as the square of velocity.
There's plenty that can be done to made sure the 170 YOU have will perform at it's best. You can hide the brake lines behind the struts for as far down to the calipers as you may. You can remove unnecessary antennas. Install a spinner. Repair engine cooling baffles. (Yes, That will affect speed, as well as cooling.) You can make certain your airplane is in rig, and trimmed properly for flight. You can leave off all the unnecessary weight you normally carry in the baggage compartment.
And when you are finished..... You will make 104 knots. That's because the factory already took advantage of every concievable thing they could to achieve that advertised speed. A few extra knots might be achieved if you perform the Benham/Bartone exhaust mod (one of which it appears that Kent has) and use the large prop spinner and install wheel pants, etc. etc. But very likely a lot of money can be spent before any real speed will be realized over the 104 knots because of the rule of drag.
Most speed claims/beliefs by standard 170 owners are the result of inaccurate airspeed indicators and non-standardized, non-uniform, anecdotal testing. And when it is all over, said, and done.... You can take the fastest standard 170 and the slowest standard 170 and fly them side by side all the way from tanks full to tanks empty and one will arrive only moments before the other.
But that's no reason not to leave off unnecessary weight and clean up and rig the airframe. I carry around junk I'll probably never need. But someday, a green 170A will likely break down and need something out of my spares bag.

[zero.one.victor]

Read The 170 Book, there are at least a couple articles abut clean-up and speed enhancement. Take all claimed results with a grain (or more) of salt. A lot of work can go into clean up for a gain of only a couple mph for any one mod. And doing ten mods worth 2 mph each doesn't necesarily add up to 20 mph!
I'd say the best & easiest way to drastically improve cruise speed is to install 600X6-15 tires (probably illegal), remove all antenne (not practical) and venturi's, and run it wide open at all times. Run the highest pitched prop you can come close to redline with, wide open at low altitude. And be prepared for about 10 gph or more overall fuel burn.
Going places,I run mine at 2500-2550ish-- with 76-51 prop,800's, and a pretty dirty airframe I usually see around 120ish, with an overall fuel burn of 8 gph or a bit less.

Eric

[kmisegades]

Gahorn and Eric, many thanks for the good advice. I'll let everyone if an when I see any improvements and how attained.

[dunlaps3]

Kent, my Franklin is 220 HP. I have 2 170B's with Franklin 220 , both are great airplanes. I like the 220 hp Franklin alot . They are both reliable and smooth running. I think the people who hate Franklins probably got that from old Stinsons or Seabees. They are antiques just like Cont and Lycomings from the 30's and 40's. Both of mine are USA made from the mid-70's . I can get off almost as fast as a Super Cub or Husky and then pass them by climbing or cruising. Andrew

[kmisegades]

Andrew, thanks for info on 220HP Franklin. How is the availability of these and parts for them? Are normal mechanics able to work on them? Who has the STC for the C170 and what does it do to the cowl? I can't imagine squeezing a much larger engine into the existing cowling. Many of these came out of helicopters, didn't they? Kent

[GAHorn]

Kent, are you willing to spend $30K to get another 10-20 kts? That's the ball-park cost of any engine conversion. If so, then I'd recommend the Continental IO-360, which still has a manufacturer to support it. I don't have anything against the Franklins, other than the fact they're out of production with no mfr. and generally have low TBO's, so parts are rapidly becoming an issue.

[cessna170bdriver]

Andrew, thanks for info on 220HP Franklin. How is the availability of these and parts for them? Are normal mechanics able to work on them? Who has the STC for the C170 and what does it do to the cowl? I can't imagine squeezing a much larger engine into the existing cowling. Many of these came out of helicopters, didn't they? Kent

Kent,

Believe it or not, both the Continental IO-360 (210hp/1500TBO or 195hp/2000TBO) and the 220HP Franklin will fit under the stock cowl (one at a time, of course ). Word has it that the Frankiln certificate has been acquired by Pratt/Whitney as part of a bigger deal and they have no interest in supporting the Franklin. If you just HAVE to have more power and like the original lines of the cowling, go with the Continental. See http://www.xpmods.com/enginemods/default.asp for info on the conversion for the C170.

Miles

[kmisegades]

Miles and Gahorn, great recommendations on Conti vs Franklin. I'm still 300-400 hours away from an overhaul, so a few years out yet. However I like to think ahead and weigh all options, of which there appear to be many. Our field elevation (NC81, Cox Field near Raleigh, NC, home of EAA1114.org & two C170s) is only 450 ft however I bought the plane to fly into the Appalachias, where density altitude can be an issue on 145 HP in the hot, humid summers. Miles I just learned all about Tehachapi flying from a friend living in Lancaster, works at Skunk works & building an RV9. He sure likes flying my C170 so we may have a new convert in the Mojave. I'll make it out there one day in my bird, maybe a bit faster and with a new engine thanks to your advice.

[trake]

Im getting the 104 kts at 65% but I had to remove several antennas, the venturis and fix the floppy door latches. Next on my list is the rotating beacon and getting the brake lines behind the gear legs and removing the loran antenna. Ive also removed the bubble side windows. The best engine conversion is an o470 in a cessna 180, you can use car gas as well. With the price of fuel right now Im liking my puny O300.

[CraigH]

Not mine. I'm only running about 110mph with wheelpants. However, I've also got dual venturis and way too many stinking antennas.