Itinerant Air-Cooled

Bleyseng wrote:I was talking about the early 901 pattern.
Reverse is all the way left and forward
1st is all the way left and back to you
going to second let the spring guide you slightly right into second from 1st so you don't nick reverse

Darnright 901.. I had it wrong from memory.. sorry.
It is quirky at that!
Nicked reverse a whole lot myself.Miss that spring plate.
Apologies

Fun to banter even haphazardly about things 901 and 914teenish.

Back to the thread?

I put air scoops on Bus to augment cooling air. (8.6:1 cr)
Thinking being if incoming cooling air was augmented, added to,perhaps have a bit extra waiting around the engine compartment to be scooped into the impeller airfoils, might it ease the fan impeller's job?
My research was nil, but result last summer when I lost one, showed oil temps trended beyond happyville, and this was at 65 on hilly Connecticut's Merrit pky.
I refabbed some for that trip. Keep them on now. As they keep rain and snow mostly out while parked.
I block off half now for these single digit celcius days to manage 300°f head heat.(aircraft spruce gauge)
Egregious, yet ok.

What is "Happyville" to you for oil temps? With a oil cooler up front you shouldn't ever have problems with oil temps going beyond 220F.

We lost a couple of days replies.
What's the current situation?
Colin

Status

260°fOil temp is not a suprise (when heat soaked)at a.shimmering desert gas station.
230, 240,250 expected when doing the work.
Timing and AFR should be well dialed when operating in this enviroment.

Bseng had some real life comparisons with T4 in Bus/and his 914.

//Eric

Great thread....So I just installed an 091 transmssion with 5.42 ring and pinion to compensate for larget tires. I have the unique opportunity to now try and select a tire size that will put me into ideal RPM/MPH range for my driving application. I'm trying to figure out if simpy trying to mimic/work from stock gearing is the best way to do this or I should take into consideration other factors? These include: Drive bus loaded down with gear most of the time, I drive to the sierra mountains (tahoe) for Kayaking and camping primarily, I have the 142 grind on stock 78 Type 4 F.I. engine with exception of larger valves, and extractor exhaust. I'm also going to run heavier tires with more tread resistance.

So....should I look at stock rpm/mph and maybe just reduce tire size down to compensate for my application of mountain driving, and being heavy? I beleive a 29" puts me 6mph under stock at 4000 rpm's. OR...should I use the 4200 optimum fan speed for cruising as a benchmark? Should I put cam specs into the mix?

Any help here is greatly apprecaited as I'd love it if I can nail this calculation for reduced stress on upcoming summer trips.

campinpoptop wrote: I just installed an 091 transmission with 5.42 ring and pinion to compensate for larger tires.

I drive to the sierra mountains (tahoe) for Kayaking and camping primarily,

a) I have the 142 grind
a) on stock 78 Type 4 F.I. engine
a) with exception of larger valves, and extractor exhaust.

b) I'm also going to run heavier tires with more tread resistance.
So....should I look at stock rpm/mph and maybe just b) reduce tire size down to compensate for my application of mountain driving, and being heavy?

I believe a 29" puts me 6mph under stock at 4000 rpm's.
OR...should I use the 4200 optimum fan speed for cruising as a benchmark?
Should I put cam specs into the mix?

a) did you select these larger valves and 142 grind and extractor exhaust on this no-longer stock engine?
b) did you select or inherit this 5.42 (rear axle ratio from Europe) 091 because you had the larger tires to begin with, or did the transaxle get built for a car that had larger tires to begin with? Do you know the 4th gear ratio? Factory was .82 up until the 5-rib when it was raised to .89.

campinpoptop wrote: Any help here is greatly appreciated as I'd love it if I can nail this calculation for reduced stress on upcoming summer trips.

I don't know if I can be of any help because you have an array of variables here. I have no idea how the engine is running. I have no idea where its torque or horsepower peaks are. I don't know where the stress of driving to Lake Tahoe is to be found. If it is just a bunch of 3rd gear hills, well, that is nothing new under the sun for a VW bus, loaded or otherwise.

I have driven the Sierras and the Rocky Mountains with
a 1973 bus, a 1978 bus, and a 1970 bus,
they all had factory torque peaks at about 3,000 rpm,
with horsepower peaks at 4,800 rpm and 4,200 rpm, and 4,400 rpm,
with stock camshafts, stock exhaust systems,
stock rear axle ratios of 4.86 and 4.57 and 5.38 : 1, each with 27" tires,
which gave me 3rd gear pulls of 43 and 45 and 40 mph respectively,
and they all did/do/shall do fine.

The only thing I do is inflate the tires, tune them up, make sure they are clean, and drive.
Colin
(please note that once you have downshifted, it is YOU who determines the fan speed/heat generation most of the time because once you have downshifted, it is mostly up to you how fast you are going to go in 3rd gear.
On the highway, 4th gear, floored for 16 miles straight outside of Baker on I-15 north, then the engineering of your engine/cooling gear ratios/tire sizes becomes important because you know that you are going to have the accelerator pressed for most of the time)

Colin....are you saying that I need to have it put on a dyno to determine peak torque and horsepower before moving forward to a decision? The other questions you are asking should probably go on another thread about how I ended up with what I have, no? If I'm understanding your response correctly you are saying to use stock gearing as the target so I too can achieve what you have at stock. However your total non camper weight or tire resistance is not what mine is, so where do I go from here to compensate?

Also 4th is .89.....only ring and pinion was changed out.

campinpoptop wrote:Colin....are you saying that I need to have it put on a dyno to determine peak torque and horsepower before moving forward to a decision?

I would analyze the current set-up with a simple drive. Does it accelerate in a nice linear fashion? Are there big rpm drops between gears, or does it seem to shift with an appropriate "next gear-let's go" sort of pull?

campinpoptop wrote: The other questions you are asking should probably go on another thread about how I ended up with what I have, no? If I'm understanding your response correctly you are saying to use stock gearing as the target so I too can achieve what you have at stock.

I am not able to tell you what to do, because I have no point of reference here.

campinpoptop wrote: However your total non camper weight or tire resistance is not what mine is, so where do I go from here to compensate?

I do not think that "tire resistance" or total camper/non-camper weight is anything I can determine. I do not know of tire resistance as a factor here off of the Talledega race course.
A camper weighs 250 lbs more than a seven-passenger bus.
I know that I have 250 lbs of tools and inventory.
I reckon all of us ship between 100 and 400 pounds of passengers at any given time.

If you *have* a 5.42 rear axle and a .89 4th gear, you are set up for mountain driving, lots of revs on the highway . . . can I please ask where and how you arrived at this unusual set-up? Did you *inherit it* or was it *recommended to you* and you executed it?
Colin ?

Linear acceleration is great with current 26.5" diameter tires. Just feel like it needs to be shifted into 5th on flat hwy speeds. This is what I'm trying to make my decision around. Previous stock r & p heated my head temp up to 415 holding steady at 65mph on long flat hwy drives and quickly up to 450 climbing. I don't want to have these same high head temps because of opposite problem --running at too high of rpm's. This is why I was wondering if I can calculate to be at an appropriate cooling rpm at 65 yet still bring down the torque curve a bit for mountains and maybe find my sweet spot.

Nobody recommended the 5.42 setup. It is all me experimenting with larger rim/tire to improve side to side sway with a loaded camper and roof rack. I have found it to improve stability more than any other maintenance or modification and want to keep it. I hesitated to answer this question because the list of what I've already done is long, thorough, and we've discussed in person years ago. (Trust that I've done everything else before making the decision to change wheel/tire) You shared with me that the bus is designed to have a break away and I am influencing that with larger/wider rims/tires. I am OK with that having had some extremely scary moments driving through switchbacks amongst huge granite walls/cliffs on hankook properly rated tires where I felt like at even low mph we were going to roll off the cliff being so top heavy. To keep this modification I wanted to lower my gearing. 5.14 r & p is only available in race grade and very expensive. I looked at putting in a 002, but ultimately decided on having the 5.42 installed in a spare 091 I had in a shed - so I can always go back to stock since I have my original transmission.

campinpoptop wrote: A) Previous stock r & p heated my head temp up to 415 holding steady at 65mph on long flat hwy drives and quickly up to 450 climbing. I don't want to have these same high head temps because of opposite problem --running at too high of rpm's.

Who said your stock ratio was heating up your heads?
Who said that a shorter ratio would heat up your heads?
What if your heads are heating up because there is a problem with the engine? < likely

campinpoptop wrote: The 5.42 setup is all me experimenting with larger rim/tire to improve side to side sway with a loaded camper and roof rack. I have found it to improve stability more than any other maintenance or modification and want to keep it.

Got it.

campinpoptop wrote: larger/wider rims/tires To keep this modification I wanted to lower my gearing.
having had some extremely scary moments driving through switchbacks amongst huge granite walls/cliffs on hankook properly rated tires where I felt like at even low mph we were going to roll off the cliff being so top heavy.

Sorry. You have galloped into a labyrinth of conflicting goals with some subjective sensory feedback that does not necessarily how shall I say . . . . meet the road. I see this a lot on theSamba, where people rave about their new heavy duty sway bars front and rear, and yes, the car feels like it is on railroad tracks, but I swear to God, they know not the hell they are going to unleash upon themselves and their families at the first emergency swerve.

Try to give me a real scenario a real, thought-out scenerio with the Hankooks where the car would lose control. Think it through. Then give me the same environmental circumstance with the larger tires. How would your car behave differently?

You might end up hating me . . . but I have to seize the information I have been provided here and I have to categorize, edit, filter, apply to the knowledge base, and help you achieve clarity.
Colin

That's easy.....Hankook's: Remember this exact situaton -- driving on interstate over altamont pass at 65mph. Large gust of wind hits the bus (this location is where the windmills are for a reason). I swerve all the way into the other lane while trying to correct but not over correct. "If" another vehicle would have been there I would have hit it and spun out on the road risking hitting other vehicles on the hwy. With new wheels -- same scenerio I feel a slight pull from the wind at least 50% less, I'm able to correct while staying in my lane not risking hittting another car. Oh no! here we go! Was trying to avoid this back and forth.

Amskeptic wrote:

72Hardtop wrote:Hey Colin...

I noticed on your chart for the 72 shift points it shows 78mph @ 3,900 rpm and to the right for 4th gear it shows 30 - 78mph 1800 - 4700rpm.

Which is it at 78mph for the 72 with the 3-rib? 3,900 or 4,700rpm? I was under the impression it was around 4,200 with the 3rib and 185R14's.

Given I have a 2056cc with a 3rib 002 and running 185R14's how close to the 091 gearing would a set of 195R14's get me?

I fixed that writeographical error. What an involved process that was. When your browser cache/cookies flush, the correction should show up.

195s do not qualify as "freeway flying" over the 185s. Rotations per mile is 2.3 % less with the 195s, and the speedometer reads 1.4 mph lower with the 195s. Your engine would benefit from about 100 fewer rpms per mile.

4,200 rpm with the 002 5.375 rear axle? 70 mph.
Colin
(thanks for pointing that error)

So with the 195's how much less (rotations) per mile would it be approximately? Would it be more than 100 fewer per mile?

72Hardtop wrote:

Amskeptic wrote: 195s do not qualify as "freeway flying" over the 185s. Rotations per mile is 2.3 % less with the 195s, and the speedometer reads 1.4 mph lower with the 195s. Your engine would benefit from about 100 fewer rpms per mile.

So with the 195's how much less (rotations) per mile would it be approximately? Would it be more than 100 fewer per mile?

For the engine or tires?

Engine, "about 100 fewer."
Tires, about 118 fewer rotations in 4th?

Robbie