Got a new 914!, Post 2011 Evil Tranny Clinic update: Options

[Root_Werks]

914 has been sitting in winter storage for about 3 months. This weekend was cold, but very clear skies and sunny. So the wife and I headed up to the storage hanger and dug out the 914. We put almost 200 miles on it over Saturday and Sunday. It felt nice to drive a 914 again. I snapped a quick picture when we brought it back to the hanger.

I can't wait until spring to start driving it daily again. (IMG:style_emoticons/default/driving.gif)

[Rand]

Dan, do tell about the hangar.
A great friend of mine had a sweet hangar at the Arlington airport. I'm guessing that's near to you.

Here's a pic from an aerobatic flight from there with my friend Anne.
I love airports.

That Cascade Mtn Range is Spectacular.

[Root_Werks]

My buddies place at Skagit, I don't get any stick time behind fixed wing anything these days (Too much $$$$!). He's got some cool ground-based toys I get to pilot once in a while though. 59' Vert-D, the yellow 65' C you can see in the picture and a handful of VW bug's from the 60's and 70's.

It's a really nice drive up to Skagit and once we're there, we usually spend the day up there. Visit Camano Island, LaConner etc. Makes for some great little towns and cool twisty roads.

(IMG:style_emoticons/default/driving.gif)

[flipb]

Don't forget to adjust for Porsche's or maybe VDO's inaccuracy of the speedo.

I've never been in a 914 that was less than 5% off, most are 10-15% off actual speed.

Mine is 8% off with my 185/65/15's. So I always subtract that off the total miles traveled when calculating mpg figures.

Otherwise I would have already touched the 40mpg mark! (IMG:style_emoticons/default/rolleyes.gif)

I plan on sending my speedo in and having it re-calibrated with my current tires.

Annoying to see 70mph when you're only going roughly 60mph. (IMG:style_emoticons/default/dry.gif)

"Look, look! We're going 100mph!" (IMG:style_emoticons/default/driving.gif)

Wow. I've heard people joke about inaccurate speedometers before, but mine seems much, much better than most. My only point of reference is those portable radar installations that the police put up. The 914's Speedometer is always almost exactly aligned with what the radar shows. My DD (a '07 Kia) is much worse, speedo runs about 10% optimistic (e.g. shows 77 when I'm driving 70).

FWIW, I'm running Kumho tires that I think are stock size, or close to it.

On the downside, my Odometer doesn't work and the Speedo needle has started bouncing a lot, so I need a rebuild... but hope it comes back as accurate as it is now.

[Root_Werks]

Bouncy needle is a worn out cable, do that first, it'll smooth things out.

My mpg figures are always corrected numbers. With my 185/65/15's I'm about 7% off actual speed. Not bad.

Stock tires I think are 165/SR/15's which I've thought about moving to just to correct the speedo and reduce the rolling resistance for hopefully even better fuel economy.

(IMG:style_emoticons/default/idea.gif)

I also thought about pulling the 2.0 for a 1.8, but I just can't de-value this car like that. Which leads me to possibly trading it for a 1.7 or 1.8 914?

(IMG:style_emoticons/default/idea.gif)

I really want to see if I can build a 40+mpg 914. (IMG:style_emoticons/default/driving.gif)

[Tom_T]

Haven't been on here for awhile Root/Dan - but you've re-inspired me on mine to keep cranking away, although I've realized I need to do some other "building projects" to fully free up my garage to keep mine on stands/rotisserie full time without rolling it out/jack-up & jack-down/roll back every friggin' time! (IMG:style_emoticons/default/dry.gif)

On to your tires & mpg ....

No don't swap in a 1.7 or 1.8, nor trade down for one. If anything & if you don't need to smog test it for DMV up there, then back date your 76 2L to 74 spec (since 73 has some hard to find NOS parts that were 1 MY only) - with D-jet, 2.0 SSIs you have & a OEM 2.0 Banana Muffler (quieter than Bursch) & tune it to factory specs, get stock 165R15 tires on there, then go drive it "easy" for best milage, and you should get close to 39 or 40 mpg on the flat highway (city & mixed & hills will be less due to more work.

The biggest input by far affecting your mpg is attached to the end of your right leg - waaay down there! (IMG:style_emoticons/default/biggrin.gif)
Yup - that foot on the gas pedal, along with gear selection - not changes, but which one you stick it into to cruise! (IMG:style_emoticons/default/driving.gif)

Third may be the wheels, as the Fuchs 2L lightweight forged alloys were 10.1 lbs. IIRC, while the Rivieras you're running are probably 13-14+/- lbs. each - so that affects the overall weight, and also the rolling resistance & inertia which the motor needs to overcome to spin the wheels (also affected by tire size below).

Second may be the tires - & there were several questions posted here on sizes, speedo/odo errors & mpg, so I'll offer my 2 cents.

Going to 165(/80)R15 - BTW 2.0's were stock spec'd for 165HR15 & 1.7's/1.8s for 165SR15, but you can drive 2L's with SR's if you're not testing the limits over their 112 mph speed rating. HRs go to 130 mph & TRs go to 118 mph, but latter weren't available back in the day, so not spec'd. The 73-74 2.0 was spec'd as 115 or 118 mph max., but I've had my totally stock 73 2L up to 126 mph. The 75-76 was 112+/- mph IIRC. So what are your choices now?

There are Kumho & several other 165SR15 tires around at reasonable under $100 prices, as well as the Vredestein Sport & Michelin XZX are over $100 (Michi well over!).

Bridgestone makes a nice 165TR15 for $70-90+/- that looks nice & grips well according to some local 70's 911 & 912 guys who run them.

Only Vredestein Sport+ ($105+/-) & Michi XAS (tube type @ $280 w/ tube) are currently available in 165HR15, but I've got a poll post topic to try to get Dunlop to bring back their SP57 165HR15s, in the garage (vote there for price & number of tires if you're interested.

All stock spec tires were tubeless because the steel & alloy "J" rims were for tubeless, & I'd been told those can pinch & pop tubes if you use tube-type tires in them (either at installation or while driving & flexing the sidewalls - per tire experts back in the day.

The 914 Speedometers & Odometer were not inaccurate - especially as compared to other cars of that day, and particularly with American makes. Perhaps a fraction or 1% off at most. However, they were geared specifically for the stock OE tire size of 165R15, and not the "low-n-wide fatties" that many like to run today for max grip!

The OE spec 165R15 tires (/80 height to width ratio) will give a zero speedo/odo error - or maybe a fraction of a percent if gears are worn, since that's the size the speedo & odo are geared for. They'll also seem quicker to turn since the smaller contact patch is less resistance on non-power steering - not better gripping, but the price for more grip is less mpg on larger & wider/lower profile tires like yours.

Michelin 185/70VR15 XWX tubeless tires are 0.8% too fast & 195/65R15 are double that at 1.6% - while your 185/65R15 are 3.8% off fast (so you're over correcting at 7%), & 185/75R15 are 2.1% too slow, & 175/75R15 is only 0.2% off fast - but I've not seen any recently. Those 185/70VR15 XWXs were the optional upgrade on the M470 & M471 factory options for the 914/4 & 914-6 respectively,and many AXers & racers back in the day used them cuz they were sticky but drops your mpg. Today they're north of $400 apiece! (IMG:style_emoticons/default/blink.gif)

I'd also guess that your 75 2.0L would get better mileage if fitted out with the stock D-jet (74 or 75-76 MY as noted above), and I don't know if L-jet is better or worse, but the factory didn't convert the 2.0s to L-jet when it came out in the 74 MY on the USA 1.8Ls, so I presume there was a reason, since the L-jet was supposed to be less expensive to build. Ditto for the back-dated exhaust, but with the stock Banana (Bursch was tuned for HP, not mpg - whereas OE balanced the two). Of course, you'd want to pull off any smog equipment for the 75-76 set-up if you don't need to smog test it up there, since the 73-74 set-up produced 91/95 hp vs. 81/86 hp for 75-76 set-up, as well as getting better mpg.

I know for a fact that it is possible to eek a stock 914 2L up to or over 40 mpg with careful driving - most/all in 5th. Back in the late 70's I took my stock 73 2L from LA to SF & filled up near Bakersfield & again up at the north end of the San Joaquin Valley - so I had mostly flat land (a stock 914 can easily do LA to SF with gas to spare), get my right foot "soft" on the gas, stayed mostly in 5th (even on those small grades near Coalinga), kept it mostly to the 55-65 mph range (55 was the limit back then (IMG:style_emoticons/default/dry.gif) ) and I got about 41 mpg - but was bored stiff!! (IMG:style_emoticons/default/biggrin.gif)

BTW - I had the same time & money conflicts with getting stick time while raising my kids. Now that they're grown & gone, I hope to do a kit plane or restore an older Bonanza after my 914 is done!

Cheers! (IMG:style_emoticons/default/beerchug.gif)
Tom
///////

[Root_Werks]

Interesting, one year later and I still own the 914. Odd.....for me anyway. (IMG:style_emoticons/default/blink.gif)

[PeeGreen 914]

Seems like a long time (IMG:style_emoticons/default/happy11.gif)

[r_towle]

Interesting, one year later and I still own the 914. Odd.....for me anyway. (IMG:style_emoticons/default/blink.gif)

If you (when you) decide to sell that VW....consider me interested.

rich

[Root_Werks]

Interesting, one year later and I still own the 914. Odd.....for me anyway. (IMG:style_emoticons/default/blink.gif)

If you (when you) decide to sell that VW....consider me interested.

rich

I have a thread over on the samba about the Monster Squareback if you want to read up more on it. There is a small line of folks that want it. I'd be kinda foolish to sell it becuase I would just try to replace it with something similar. i.e. aircooled off road rig like a Thing or Class 11 bug or another T3 etc. So I'll probably just keep it.

(IMG:style_emoticons/default/driving.gif)

Here's a shot from painting it last fall:

[Valy]

Bouncy needle is a worn out cable, do that first, it'll smooth things out.

My mpg figures are always corrected numbers. With my 185/65/15's I'm about 7% off actual speed. Not bad.

Stock tires I think are 165/SR/15's which I've thought about moving to just to correct the speedo and reduce the rolling resistance for hopefully even better fuel economy.

(IMG:style_emoticons/default/idea.gif)

I also thought about pulling the 2.0 for a 1.8, but I just can't de-value this car like that. Which leads me to possibly trading it for a 1.7 or 1.8 914?

(IMG:style_emoticons/default/idea.gif)

I really want to see if I can build a 40+mpg 914. (IMG:style_emoticons/default/driving.gif)

Your speedometer and odometer inaccuracies are not related. Those are two function bundled in the same gauge just because they both depend on the same cable. Use a GPS for exact measurements and calibration.

[Root_Werks]

[quote name='Valy' date='Apr 6 2011, 01:07 AM' post='1454458']
[/quote]
Your speedometer and odometer inaccuracies are not related.
[/quote]

(IMG:style_emoticons/default/blink.gif)

I must be dumber than I look.

[PeeGreen 914]

Bouncy needle is a worn out cable, do that first, it'll smooth things out.

My mpg figures are always corrected numbers. With my 185/65/15's I'm about 7% off actual speed. Not bad.

Stock tires I think are 165/SR/15's which I've thought about moving to just to correct the speedo and reduce the rolling resistance for hopefully even better fuel economy.

(IMG:style_emoticons/default/idea.gif)

I also thought about pulling the 2.0 for a 1.8, but I just can't de-value this car like that. Which leads me to possibly trading it for a 1.7 or 1.8 914?

(IMG:style_emoticons/default/idea.gif)

I really want to see if I can build a 40+mpg 914. (IMG:style_emoticons/default/driving.gif)

Your speedometer and odometer inaccuracies are not related. Those are two function bundled in the same gauge just because they both depend on the same cable. Use a GPS for exact measurements and calibration.

I'm confused (IMG:style_emoticons/default/blink.gif) They are not related to what exactly? (IMG:style_emoticons/default/confused24.gif)

[Tom]

Or related to whom?? (IMG:style_emoticons/default/biggrin.gif)
Mine are off more as I have 195x55x15's and the speedo and odometer are off by about 10%. Does give me a little better low end tho'. (IMG:style_emoticons/default/happy11.gif)
Dan, never thought you were dumb at all. (IMG:style_emoticons/default/smile.gif)
Jon, you have too many 914's at your house, buy mine and have one more.
Just kidding!
Tom

[DanT]

speedo and odo are driven off the same cable, off the same gear on the tranny.
If one is off, then why wouldn't both be off.
When I use my GPS it shows my speedo and odo off by about 10% fast since I run 205x50x15s (IMG:style_emoticons/default/smile.gif)

[Tom_T]

He must mean "not related" in the "biblical sense" - as in "kissin cousins"! (IMG:style_emoticons/default/biggrin.gif)

Valy contradicts himself in his reply, when he goes on to say that the speedo & odo are "bundled" and use the same cable. I think he just meant that they're 2 separate instruments, cuz they're obviously both running off the same speed/distance data source - the cable/angle drive (or electronic in newer cars).

In the "old days" of pre GPS, we just got the speedo error from a test station or by math on the differing circumference of the tire/wheel combo off of the stock one - I even used to use my slide rule! (IMG:style_emoticons/default/blink.gif)

Today all you need to do is go to the top of this page, click on 914 info, then click on the tire calculator, plug in your new tire info (wheel diameter is implicit in tire size), and it gives you the error! How easy is modern stuff like (IMG:style_emoticons/default/type.gif) computers! (IMG:style_emoticons/default/piratenanner.gif)

Then use the error calculated either way to adjust to your actual miles driven to calc your true mpg .... you can even use one of those new fangled calculators - I even have one on my watch! (IMG:style_emoticons/default/smile.gif)

So unless having your mpg out to 4-5+ digits is important to you within a 3' accuracy from a satellite - GPS is not necessary to do this exercise - but rather a fun toy to push more buttons on! I'm not against new advances, just that sometimes it's overkill in some cases.

Back to my original suggestion - tune the 2.0 properly to factory spec - not for more power/TQ/etc. - put the few available 165HR15 or Bridgestone 165TR15 tires on the 10.1 lb. Fuchs 2L alloys per OE spec on the 73-76 2Ls (you can even cheat with cheaper Kumho 165SR15s if you promise never to exceed 115 mph), inflate to proper tire pressure or a little higher, and you'll get into the mid-high 30's in 5th on a flat freeway run if you lope along at 55-65 mph. I've done it on I-5 in CA's Central Valley. The problem is, who wants to drive a 914 that lazily!? (IMG:style_emoticons/default/huh.gif)

That's what Porsche spec'ed them for back in the 70's gas crisis days - 29-33+ mpg at 55-65. It's also a big reason why I decided to get rid of my 69 Pontiac Ventura 4-dr. 400cid/2bbl/Auto "Boat" in 75 (I'd taken over It & its payments from Dad on it when my 1.1L economical Opel Kadette engine blew in 71) ~ aside from the obvious advantages to a young single guy wanting a sports car! I didn't sit in gas lines nearly as much in the 914-2.0 after 12/75!!!! (IMG:style_emoticons/default/smile.gif)

BTW - when I was a Freshman in college HP sold a basic +, -, x, / function calculator ~ maybe there was % &/or square root in there too ~ for $400 - so I stuck with my mini slide rule. By Junior year others had figured out how to make the same thing cheaper, & I got another "off brand" from JC Penneys for $79. That was 1970-73. By grad school in 84-86 HP was selling their programmable HP12C financial calculator for $79 with loads of functions - today it till sells for the same price 25 years later! (IMG:style_emoticons/default/blink.gif)
Wazzup wid dat!!?? (IMG:style_emoticons/default/confused24.gif)

[Tom_T]

PS -

Another thought for those of you running off-size tires with large odo errors, you may be devaluing your 914s some by having more mileage than actual showing, or conversely giving the eventual buyer & yourself under mileage when it comes to service intervals & actual use on the car, engine, transaxle - depending upon whether it's a + or - error.

Obviously the over mileage is the most harmful when selling, as Tod914 found out when he sold his white 75 or 76 2L (IIRC that was the car) after restoring it but running on 195/65HR15s - which is only a 1.6% error IIRC, cuz it took a very low mileage 914 & put an extra 5-10k or something of "ghost mileage" on there. I don't know how much cash he lost in the sale, but maybe he'll weigh in here on the dangers of off size tires to a collectible vintage car.

If your 914 is highly modified then it may not matter as much, cuz that buyer segment isn't as interested in actual mileage, but rather in the performance tweaks & mods you've done.

The least or zero error tire would be the 165R15 (80 section presumed for all, but they do vary some) in either SR, TR (new rating not around in the 70s but adequate for 2Ls), HR, VR, etc. speed ratings. Next best is 185/75R15 - of which I've seen zero, or the 185/70R15 with only a 0.8% error of which Vredestein makes VR & maybe HR for a somewhat reasonable price, & Michelin makes the old school AX/Race/HP tire from the M471/M470 option set XWX 185/70VR15 at a whopping $407+/- per tire! (IMG:style_emoticons/default/blink.gif)

I know a few 356, 911/912 & 914 folks around who run the Kumho 165SR15 & Bridgestone 165TR15 modern tires, as well as a few with the Vredestein 165SR15 or 165HR15 & Michelin XZX 165SR15 or XAS 165HR15 (those Michi's are +/- $200-250 eaqch & XAS require tubes which are not supposed to be good on our "J" type tubeless rims/wheels) vintage-look tires for DD, vintage & CW use who are relatively happy with their performance as well. Obviously not the oversized 195, 205 & up type performance, but also not the price, rolling inertia to overcome, & rolling friction to drag down your mpg - if that's what you're looking for.

The O&H nailed forum on Wheels & Tires has more info on OEM & current tires for those interested - whether your a CW wanker or not! (IMG:style_emoticons/default/biggrin.gif)

JM2C (IMG:style_emoticons/default/shades.gif)

[PeeGreen 914]

PS -

Another thought for those of you running off-size tires with large odo errors, you may be devaluing your 914s some by having more mileage than actual showing, or conversely giving the eventual buyer & yourself under mileage when it comes to service intervals & actual use on the car, engine, transaxle - depending upon whether it's a + or - error.

Well, for service of the engine you actually should go by the odometer readings as that IS how many "miles" you have put on the engine.

[Tom_T]

PS -

Another thought for those of you running off-size tires with large odo errors, you may be devaluing your 914s some by having more mileage than actual showing, or conversely giving the eventual buyer & yourself under mileage when it comes to service intervals & actual use on the car, engine, transaxle - depending upon whether it's a + or - error.

Well, for service of the engine you actually should go by the odometer readings as that IS how many "miles" you have put on the engine.

No - if you have a tire size speedo/odo error, then it is NOT how many "miles" you've put on the car.

If your tires are running off by say 10% lower than spec 165R15s, then the odo reading of 5,000 miles for a valve adjustment is actually at 5500, and you should really do your valves at +/- 4500 - or at an adjusted mileage reading per your owners manual reccos if it's not 5k recco.

Generally if you're 10% high, then you're just doing maintenance earlier than required, but you suffer having incorrectly high mileage reading on the car.

Remember - same cable or electronic data source for speedo & odo means that they're BOTH off in correct mph & miles driven.

[PeeGreen 914]

PS -

Another thought for those of you running off-size tires with large odo errors, you may be devaluing your 914s some by having more mileage than actual showing, or conversely giving the eventual buyer & yourself under mileage when it comes to service intervals & actual use on the car, engine, transaxle - depending upon whether it's a + or - error.

Well, for service of the engine you actually should go by the odometer readings as that IS how many "miles" you have put on the engine.

No - if you have a tire size speedo/odo error, then it is NOT how many "miles" you've put on the car.

If your tires are running off by say 10% lower than spec 165R15s, then the odo reading of 5,000 miles for a valve adjustment is actually at 5500, and you should really do your valves at +/- 4500 - or at an adjusted mileage reading per your owners manual reccos if it's not 5k recco.

Generally if you're 10% high, then you're just doing maintenance earlier than required, but you suffer having incorrectly high mileage reading on the car.

Remember - same cable or electronic data source for speedo & odo means that they're BOTH off in correct mph & miles driven.

So does your engine, transmission, and other rotating componants have no effect from having to turn more revolutions due to the smaller tires? I was always taught that it wasn't really about the distance traveled but more about the amount of work the rotating pieces had to do. So in this case I see the engine did 3,000 miles of work while only actually traveling a shorter distance. (IMG:style_emoticons/default/confused24.gif)