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

[Root_Werks]

This is a better chart for the gears to show how much difference the X and flipped H gears make. I'll print and file this one in the "Stuff I've done to the 914" folder:

[mburkhart]

This is very interesting. I've always found 4th and 5th to be disappointing for how high they rev at 50-70mph. How common is it to change out the high-end gears like this? Any issues to be aware of?

[Root_Werks]

This is very interesting. I've always found 4th and 5th to be disappointing for how high they rev at 50-70mph. How common is it to change out the high-end gears like this? Any issues to be aware of?

I have been warned by some that turning such low rpms at higher speeds will increase head temps. Makes sense and is probably very true. I think one of the key factors to making something like this work is having a tall enough 4th you can run at 60mph if needed (for hills and such) and having a healthy, torque filled engine.

I have a stock 2.0 with L-Jet and would put money down I produce more torque than a stock 2.0 with D-Jet. I also don't run 205 steam roller tires. I stick with 185's pumped to 40psig to reduce my rolling resistance as much as possible. Given all that, so far, so good!

Loving this combo, simply loving it!

It's so nice blowing by people at 75mph and only turning 2700-ish rpms.

(IMG:style_emoticons/default/driving.gif)

[KELTY360]

You need to spend less time (IMG:style_emoticons/default/type.gif) and more time (IMG:style_emoticons/default/driving.gif) so you can post some new MPG numbers with this config. (IMG:style_emoticons/default/poke.gif)

[Root_Werks]

You need to spend less time (IMG:style_emoticons/default/type.gif) and more time (IMG:style_emoticons/default/driving.gif) so you can post some new MPG numbers with this config. (IMG:style_emoticons/default/poke.gif)

I rode my bicycle into work today. (IMG:style_emoticons/default/sad.gif) but (IMG:style_emoticons/default/smile.gif) because the sun is actually out.

So far, I've gone....155 miles I think? The needle is just below the 3/4 mark. Back of the napkin calc's would have me initially say that is a few more miles than usual. We'll see after a few more weeks of driving.

My Squareback is under the knife for rear brake repairs, so the 914 is the current driver. I should be able to rack up some good miles in a few weeks, fill the tank a time or two. I'll post mileage figures here.

(IMG:style_emoticons/default/driving.gif)

Sooooooo, do you have your box back in your car yet? (IMG:style_emoticons/default/poke.gif)

[KELTY360]

You need to spend less time (IMG:style_emoticons/default/type.gif) and more time (IMG:style_emoticons/default/driving.gif) so you can post some new MPG numbers with this config. (IMG:style_emoticons/default/poke.gif)

I rode my bicycle into work today. (IMG:style_emoticons/default/sad.gif) but (IMG:style_emoticons/default/smile.gif) because the sun is actually out.

So far, I've gone....155 miles I think? The needle is just below the 3/4 mark. Back of the napkin calc's would have me initially say that is a few more miles than usual. We'll see after a few more weeks of driving.

My Squareback is under the knife for rear brake repairs, so the 914 is the current driver. I should be able to rack up some good miles in a few weeks, fill the tank a time or two. I'll post mileage figures here.

(IMG:style_emoticons/default/driving.gif)

Sooooooo, do you have your box back in your car yet? (IMG:style_emoticons/default/poke.gif)

Not yet, I've been too busy searching my shop for a missing spark plug, can't seem to find it anywhere. Got any idea where I might have left it? (IMG:style_emoticons/default/slap.gif)

[Dr Evil]

I am glad that, despite my warnings based on conventional wisdom, you are proving this combo so far (IMG:style_emoticons/default/smile.gif)
(IMG:style_emoticons/default/popcorn[1].gif)

[Root_Werks]

I am glad that, despite my warnings based on conventional wisdom, you are proving this combo so far (IMG:style_emoticons/default/smile.gif)
(IMG:style_emoticons/default/popcorn[1].gif)

Well, you should know from personal experience working side by side with me, I tend not to follow your direction.

(IMG:style_emoticons/default/biggrin.gif)

Marc,

I'll overnight that spark plug back to you. I even cleaned it and re-gapped it for you. (IMG:style_emoticons/default/happy11.gif)

[Eddie914]

Gearbox is back in the car - (even taking time out for Mother's Day, a couple of days for my wife's birthday, and three nights away to see my daughters perform in their school play).

It's the best shifting transaxle my teener has ever had!

It's only been driven around the neighborhood so testing of the new gearing in 3, 4 & 5 will have to wait until next Friday's track day.

Cheers,

Eddie

[Dr Evil]

Eddie, you are an animal. You worked later than anyone else. Wore me out, man.

[sixnotfour]

Cheers,

Eddie

Eddie is an animal no doubt. (IMG:style_emoticons/default/beerchug.gif)

[messix]

Cheers,

Eddie

Eddie is an animal no doubt. (IMG:style_emoticons/default/beerchug.gif)

Eddie's just "a little different"! (IMG:style_emoticons/default/sunglasses.gif)

[Eddie914]

Maybe I should change my screen name to:

"AnimalEddie"

a lot of people at the track have told me my teener is a "Beast".

"AnimalEddie" driving the "Beast" ????

When I first got it, some of my buddies called it "The Roach".

Cheers,

Eddie

[mepstein]

This is a better chart for the gears to show how much difference the X and flipped H gears make. I'll print and file this one in the "Stuff I've done to the 914" folder:

Where's the rest of the chart? I have a flipped H and a 6850 limit.

[Tom_T]

Using the tools from 914world, here is the stock gear chart with my current size tires:

Maybe a dumb question - but if redline is at 5600 rpm, why do these charts stop at 5200?

... and if it went to 5600 on your current tires or stock 165HR15 tires - out of curiousity what would it top out at mph?

I ask because I've had my dead stock 73 2L on 165s up to 126 mph on the speedo (stock speedo error of +/-5% aside) back in the day.

[messix]

Using the tools from 914world, here is the stock gear chart with my current size tires:

Maybe a dumb question - but if redline is at 5600 rpm, why do these charts stop at 5200?

... and if it went to 5600 on your current tires or stock 165HR15 tires - out of curiousity what would it top out at mph?

I ask because I've had my dead stock 73 2L on 165s up to 126 mph on the speedo (stock speedo error of +/-5% aside) back in the day.

How big was that fish......

Going down a very steep long hill? (IMG:style_emoticons/default/popcorn[1].gif)

[Tom_T]

Using the tools from 914world, here is the stock gear chart with my current size tires:

Maybe a dumb question - but if redline is at 5600 rpm, why do these charts stop at 5200?

... and if it went to 5600 on your current tires or stock 165HR15 tires - out of curiousity what would it top out at mph?

I ask because I've had my dead stock 73 2L on 165s up to 126 mph on the speedo (stock speedo error of +/-5% aside) back in the day.

How big was that fish......

Going down a very steep long hill? (IMG:style_emoticons/default/popcorn[1].gif)

Precisely!!!! (IMG:style_emoticons/default/biggrin.gif) - with a witness/passenger - as I wrote in my 914 trip stories topic elsewhere here in the Garage, while (IMG:style_emoticons/default/driving.gif) Northbound about midnight on I-15 through the Virgin River Gorge in SW Utah on a fast run in 1978 - leaving my Huntington Beach apt. in Orange County CA Fri +/- 6:00 pm after work, going to a Rugby Tournament that Sat/Sun in Park City UT where I had a 8:00 am kick-off! (IMG:style_emoticons/default/blink.gif)

No fish involved, but speedo error unknown, so it could've been perhaps 5% off as that was the allowed factory error back then.

[Root_Werks]

The chart I made is off the spreadsheet and I adjusted the formulas to display only what I wanted. i.e. were I think I would max my rpms and shifting for each gear. So 1st and 2nd might get close to 6k rpms, but 3-4-5 are not much about 5200 rpms.

Chart made just for me. (IMG:style_emoticons/default/biggrin.gif)

I rode my bicycle into work again today. It's bitter sweet because the sun is out, I want to drive my 914, but at the same time, I love to ride my bike. I'm hoping this weekend stays nice.

(IMG:style_emoticons/default/driving.gif)

[Root_Werks]

29.3 mpg the last tank, corrected mileage of course. Better by a couple mpg which is cool. The longest HWY trip taken was a whoping 26 miles, so still not getting a flavor of what might be achieved on a nice long 300-400 mile drive.

We are trying to get the time to drive down to OR in June for the WCR which would be a perfect drive for max mpg. Work and a possible technical certification are potentially putting the squash on that weekend. We'll see.

(IMG:style_emoticons/default/driving.gif)

[Valy]

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)

Lost track of this thread so I guess I need to add some details:
The ODO and Speedometer accuracy is related since they run on the same cable but NOT THE SAME.
Your speedometer can be off by x% but this doesn't mean that the ODO is off by same ration.
The reason is that ODO just counts wheel revolutions while the speedometer measures the turning rate. It does so by applying a low pass filter to the rotation speed. This LPF is build out of a magnet, counterweight and friction (with air). Over time, the magnet looses its properties, the weight sometimes slips and dirt gets into the speedometer adding friction. This change in properties will make your speedometer inaccurate.
It is also true that changing the tires will set everything off with the same ratio relative to whatever it was before changing the tires.
There are 2 speedos calibration out there: for 155r14 and 165r14. check the part number in the PET to findout what tires it was calibrated for.

Bottom line is that the ODO is usually pretty accurate for the tire size it was designed while the speedo will be off with time. Also the speedo is no linear and DMV rules mandate them to never be pessimistic (never show less speed than reality)