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Thu Jan 12, 2017 9:18 pm

vwible wrote: Quote: I want a strong, solid, reliable engine, not necessarily a monster, speed burner. Just one to be able to pull the hills and not over-strain the engine.

My experience:
I bought a used '70 bus which had a 1904 (74 stroke x 90.5 bore) in need of serious attention. Pulled engine out, cleaned it up but did not touch the bottom end as I was told the engine was installed in the past few years. Cylinders had nice clean crosshatch marks and not too much carbon when I pulled the heads off. The owner wasn't mechanically inclined so tuning and maintenance was suspect.

I replaced the heads with new, mildly-ported KS1000's 40 x 35.5 valves, new 1:1 swivel feet rockers, and obsessed on the re-assembly as I'm an amateur. Engine build books, the Samba, and the Bentley help here. I took a shot at match-porting the intake manifolds to the profile of the intake ports.

Cam has .420 lift. 53 cc volume on the heads. Math works out to about 8.5 compression radio. Carbs are Solex/Kadrons with 28mm venturis, and rebushed throttle bodies. Not sure about jet sizes, but whatever they are work well. I re-used the exhaust system that came with the bus: stock heater boxes to a tube header and a Duramax muffler. It is an upright cooled engine, but I did the type 4 oil conversion with the shroud extension.

Results: Nice torque as is. I'm sure I can get more out of it if I put a larger exhaust on it. With the freeway flyer transmission the bus holds its on on the highway over extended runs, but pulls nicely around town and on long hills. About 4,500 miles on it at this time and yes, I'm obsessive about oil changes and valve settings. In the two years I've had it on the road the only thing that shut me down was a plugged-up fuel filter. That's on me for not changing it as part of regular maintenance! I should have made a note in my maintenance log.

My story, your results will vary.

This sounds like a really nice motor especially in a bus. I guess we don't know the cam? If it were a W-100 it would probably run hot, may be something with more advance. The nice thing about the 90,5 bore is it likely allows the pistons to clear that longer stroke crankshaft. The nice thing about the 74mm stroke crank is that it's close enough to stock that with 5.325" rods it can have all stock pushrods etc...I would have opted for stock valve size heads though for the bus as they would have better low end torque and work well with the stock heater boxes. Now if it had the 36mm dells on it that would awaken the power there-in. The only way this engine is going to be quite though is with a stock exhaust which would probably not work very well heat wise and rpm wise and with the big valve heads. "vwible" Next time your adjusting the valves, note the degrees at which the intakes reach .050" lift. Probably would tell what cam it has. "Dustman985 This design could be modified just a little and would not be very much more to build than the stock rebuild. Well depends on stuff you do like Full Flow, Balancing, Case Machine work etc.... H-Beam Rods would be nice in this motor, Nice in any motor!

Fri Jan 13, 2017 6:57 am

GTV wrote: Das67bus wrote:

Cool! Then you can appreciate the challenges of trying to drive to Flagstaff or other areas here. :wink:

Budget-wise, I would like to stay around $6K. I base that on ads I've seen from the various engine builders on The Samba and in hotVW mag. I want a strong, solid, reliable engine, not necessarily a monster, speed burner. Just one to be able to pull the hills and not over-strain the engine.
No heater boxes, I pulled and replaced with J-tubes. I have dual carbs and am OK with that. The transmission is 4.12 x .82 geared from Benco Racing.

What dual carbs do you have now (assuming you want to keep them)?

I think Empi's, but I will go with a complete new engine/carbs and keep the one I have complete. I want to make sure everything matches up on the new engine.

Thanks!!

Fri Jan 13, 2017 7:39 am

Thats true, mostly the quality of parts and chosen state of tune will determine the engine reliability.

Bigger bores (atleast in theory) will run slightly more hotter, since there is less fin area. Same applies to different heads.

Medium tune engines would be probably most reliable, besides stock. But really expensive parts like aluminum tapered pushrods, MS230 heads, etc
can the highly tuned street engine be made reliable, better cooling heads, lighter valvetrain etc.

Just not too much lift and compression for pump gas.

Fri Jan 13, 2017 8:23 am

Das67bus wrote:

Would the stroker provide more torque and help power a bus better? Or does HP alone do that? I live in a mountainous area and have to drive up steep grades. The 1641 I have is a little weak.

Budget-wise, I would like to stay around $6K. I base that on ads I've seen from the various engine builders on The Samba and in hotVW mag. I want a strong, solid, reliable engine, not necessarily a monster, speed burner. Just one to be able to pull the hills and not over-strain the engine.
No heater boxes, I pulled and replaced with J-tubes. I have dual carbs and am OK with that. The transmission is 4.12 x .82 geared from Benco Racing.

And THAT is your problem! such a transmission has absolutely no place in a bus, unless you have a large, specificly built type 1 engine or even better, a type 4.
I have seen it many times, where people buy such a transmission because they want to get the rpms down, only to realize that every time their bus sees a molehill the engine is on the heels. they also often have a tendency to run hot because the constant load get much higher than the cooling capacity is at that rpm.
The last "episode" of such that I was involved in was a split bus with a 75ish hp 1600 engine and a "freeway flyer" transmission. That guy decided that he wanted the high ratio and got an engine built to suit the transmission instead. He had some left over parts from another build, among that a case and some 5,5" CB rods and 90,5 cylinders. So I built him a 84 x 90,5 (2160) with a type 4 center main bearing and type 1 rod journals. It has upgraded cooling, so it corresponds with the higher ratio. I also used a programmable vacum controlled ignition for best possible temperature control. That engine pulls almost 160 nm at 2200 rpm, peaks with about 190 at 3300 and pulls about 124 hp at 5200. Now it´ll pull the bus, fully loaded, and a small camper too if needed...
You should also decide whether you want a larger engine or you want to correct the gearing to the engine.

T

Fri Jan 13, 2017 10:08 am

Alstrup wrote: Das67bus wrote:

The transmission is 4.12 x .82 geared from Benco Racing.

And THAT is your problem! such a transmission has absolutely no place in a bus, unless you have a large, specificly built type 1 engine or even better, a type 4.
I have seen it many times, where people buy such a transmission because they want to get the rpms down, only to realize that every time their bus sees a molehill the engine is on the heels. they also often have a tendency to run hot because the constant load get much higher than the cooling capacity is at that rpm.
The last "episode" of such that I was involved in was a split bus with a 75ish hp 1600 engine and a "freeway flyer" transmission. That guy decided that he wanted the high ratio and got an engine built to suit the transmission instead. He had some left over parts from another build, among that a case and some 5,5" CB rods and 90,5 cylinders. So I built him a 84 x 90,5 (2160) with a type 4 center main bearing and type 1 rod journals. It has upgraded cooling, so it corresponds with the higher ratio. I also used a programmable vacum controlled ignition for best possible temperature control. That engine pulls almost 160 nm at 2200 rpm, peaks with about 190 at 3300 and pulls about 124 hp at 5200. Now it´ll pull the bus, fully loaded, and a small camper too if needed...
You should also decide whether you want a larger engine or you want to correct the gearing to the engine.

T

Larger engine, as stated.

The reason for the transmission first was that the original was not well built and was having problems. I had to get that taken care of first with the intention of supporting it with a bigger engine. It really did help, though, even with a 1641 engine. The next step is a larger engine, which is why I am asking for some guidance and opinions.

Your solution to the guy's problem seems to be where I want to go.

Thanks for the feedback and help!

Fri Jan 13, 2017 11:33 am

Now if that Freeway Flyer was in a light bug or ghia, no problem with the T-4. I have something similar and the T-4's torque can be felt from zero to top speed.

The original T-4 cam is a horror. Changing it makes a major difference and usually last longer then stock.

VWIBLE after putting a T-4 in, other then normal maintenance, after slamming the engine lid closed you can forget about the engine and enjoy the ride. heavy buses do put even T-4's to the test. But unlike guys that bought buses new and loaded them up like a van with a V8, guys are now aware of the weight and un-aerodynamic front they have to contend with.

Fri Jan 13, 2017 1:50 pm

nextgen wrote: But unlike guys that bought buses new and loaded them up like a van with a V8, guys are now aware of the weight and un-aerodynamic front they have to contend with.

TRUE THAT!!! :wink:

Fri Jan 13, 2017 8:36 pm

Alstrup wrote: Das67bus wrote:

The transmission is 4.12 x .82 geared from Benco Racing.

And THAT is your problem! such a transmission has absolutely no place in a bus, unless you have a large, specificly built type 1 engine or even better, a type 4.

T

A 4.12 with .82 4th was stock gearing in a bus 61-64. I think Das67bus is still running reduction boxes looking at the pics in his gallery. If not, those jersey meats on a straight axle with no RGBs is definitely gonna run like a dog!

Fri Jan 13, 2017 8:46 pm

AlteWagen wrote: Alstrup wrote: Das67bus wrote:

The transmission is 4.12 x .82 geared from Benco Racing.

And THAT is your problem! such a transmission has absolutely no place in a bus, unless you have a large, specificly built type 1 engine or even better, a type 4.

T

A 4.12 with .82 4th was stock gearing in a bus 61-64. I think Das67bus is still running reduction boxes looking at the pics in his gallery. If not, those jersey meats on a straight axle with no RGBs is definitely gonna run like a dog!

It does have RGB's. That was part of the transmission equation.

Again, this was just a part of the build plans, now looking for the right engine. That's what I am hoping to get help with, i.e., size and stroker vs. non-stroker.

Thanks!

Fri Jan 13, 2017 11:49 pm

Ok... I'd use 92's for reliable thick cylinders. Use a (small stroker) 74mm crank with 5.325" VW journal rods and you've got an easy to build and robust 1968cc. CB Panchito heads, mild Web 218 cam, dual 2 barrel 40mm carbs, 1 1/2" header.

Sat Jan 14, 2017 8:41 am

Guys recent T-4 videos -- Oil Cooler to T-4 - Engine mounts Ghia buils.

https://www.youtube.com/watch?v=S3ewTqOxRZA

https://www.youtube.com/watch?v=deD2JxpUA48

https://www.youtube.com/watch?v=niVtQBrW56I

https://www.youtube.com/watch?v=2Z0STqvNtFc

Thu Feb 23, 2017 10:34 pm

I'll jump in if I may and know I'm going to catch H for it but:

Sorry to disagree but .....The amount of energy (read heat) to move a bus at 65MPH is going to be the same regardless of how big or small the motor is or what the gear ratio is. You also do not use full power just cruising at 65MPH. Changing the gear ratio will effect your reliability because you are lower the cooling fan speed hence the air volume. The gear ratio issue isn't relevant to HP needed but it IS to fan speed. A smaller generator pulley (or a larger crank pulley) would bring the fan speed and airflow up to where you need it. The important difference with re-gearing the transmission is that you are changing the fan speed/air flow/cooling capacity to be less than what required for the energy you need to dissipate at that vehicle speed. A bigger engine isn't going to change the fan speed. The converse is true also. You can't run a crank driven power pulley (5" or less) on a street car (Especially a T2) and not blow up the motor in short order (unless you drive at 5000RPM + all the time).

No matter what size motor you put in try and get the fan shaft speed up to where it was for the stock transmission at a given RPM .

I suspect the gearing you have in your tarns will make ANY size motor overheat if you don't have close to the correct the fan speed. True, controlling the advance curve will help. Lower compression (like 6.9:1)will help and advancing the timing 5* will help. A little less fuel and hemi cut heads will help but at your (effective) final drive is 2.82 versus 4.7 stock Factor in reduction gears if you have them. Either rev high all the time or gear up the fan speed. You are running the fan at almost half the speed it needs to run at for that gear ratio.

A larger motor will generate more heat. The energy needed to make 60 HP and 140 HP is big difference and a lot of extra heat being generated. You may need to bring more air into the engine compartment.

Buy a welded, balanced fan and don't spin it too fast.

A 74mm, 76mm or 78mm Crank with thick wall 88s or 90,5's makes a nice bus motor in my opinion.

More stroke means more torque. 74 and 76 keep the motor stock width and require less case clearanceing. Bigger strokes may get into tin fitment and engine compartment issues

Thick wall P/C sets are best for heavy vehicles like T2 and T3s. There are some out there in 88 and 90.5.

You will be limited by you exhaust size in how big you can go. If you want to keep heaters it'll start getting expensive fast. You can get aftermarket heat exchangers up to 1 3/4". Stock is 1 3/8" If you want to keep your heater boxes stock the max you'll get is 90hp to maybe 105hp.

Hope this helps. my advice is worth what you paid for it.

Fri Feb 24, 2017 5:38 am

Wow! A whole lot of practical wisdom in that post. Thanks!

Fri Feb 24, 2017 7:18 am

scubaseas wrote: I'll jump in if I may and know I'm going to catch H for it (yup :) )but:

Sorry to disagree but .....The amount of energy (read heat) to move a bus at 65MPH is going to be the same regardless of how big or small the motor is or what the gear ratio is. You also do not use full power just cruising at 65MPH. Changing the gear ratio will effect your reliability because you are lower the cooling fan speed hence the air volume. The gear ratio issue isn't relevant to HP needed but it IS to fan speed. A smaller generator pulley (or a larger crank pulley) would bring the fan speed and airflow up to where you need it. The important difference with re-gearing the transmission is that you are changing the fan speed/air flow/cooling capacity to be less than what required for the energy you need to dissipate at that vehicle speed. A bigger engine isn't going to change the fan speed. The converse is true also. You can't run a crank driven power pulley (5" or less) on a street car (Especially a T2) and not blow up the motor in short order (unless you drive at 5000RPM + all the time).

No matter what size motor you put in try and get the fan shaft speed up to where it was for the stock transmission at a given RPM .

I suspect the gearing you have in your tarns will make ANY size motor overheat if you don't have close to the correct the fan speed. True, controlling the advance curve will help. Lower compression (like 6.9:1)will help and advancing the timing 5* will help. A little less fuel and hemi cut heads will help but at your (effective) final drive is 2.82 versus 4.7 stock Factor in reduction gears if you have them. Either rev high all the time or gear up the fan speed. You are running the fan at almost half the speed it needs to run at for that gear ratio.

A larger motor will generate more heat. The energy needed to make 60 HP and 140 HP is big difference and a lot of extra heat being generated. You may need to bring more air into the engine compartment.

Buy a welded, balanced fan and don't spin it too fast.

A 74mm, 76mm or 78mm Crank with thick wall 88s or 90,5's makes a nice bus motor in my opinion.

More stroke means more torque. 74 and 76 keep the motor stock width and require less case clearanceing. Bigger strokes may get into tin fitment and engine compartment issues

Thick wall P/C sets are best for heavy vehicles like T2 and T3s. There are some out there in 88 and 90.5.

You will be limited by you exhaust size in how big you can go. If you want to keep heaters it'll start getting expensive fast. You can get aftermarket heat exchangers up to 1 3/4". Stock is 1 3/8" If you want to keep your heater boxes stock the max you'll get is 90hp to maybe 105hp.

Hope this helps. my advice is worth what you paid for it.

Wow! 6.9:1 C/R, semi-hemi, advanced timing 5°. That's one hell of a time-machine, just went back 25 years... :oops:

Fri Feb 24, 2017 10:06 am

-Alex77- wrote: Thats true, mostly the quality of parts and chosen state of tune will determine the engine reliability.

Bigger bores (atleast in theory) will run slightly more hotter, since there is less fin area. Same applies to different heads.

Medium tune engines would be probably most reliable, besides stock. But really expensive parts like aluminum tapered pushrods, MS230 heads, etc
can the highly tuned street engine be made reliable, better cooling heads, lighter valvetrain etc.

Just not too much lift and compression for pump gas. so If you buy all the best parts avalible, and it's tuned corectly and booger and bubba behind the 7eleven slap that sucker togeather in thier kids sand box it should last for ever.....and of course use 77mm bore size. :wink: there is a little more to it than that.