Planning for the future: engine advice

[mrbell321]

I've got a 1972 Transporter w/, I think, a 1.7L. Engine was a remanufactured block by a PO, but I don't know for sure what it is displacing. I also assum e the transmission is stock.

What I'd like is:
1) easy starts
2) decent fuel economy(yes, I know it's a brick)
3) reliability
4) power to go 75mph
5) keep the revs under earsplitting at 75mph
6) climb those pesky hills (rocky mountains, for example)

To get the easy starts and a bit of the fuel economy, I'm going full digital engine management. Plus I just like computers over fiddly air screws and leaky jets.

Currently, it will certainly cruise at 75, but the revs are so high that it's "uncomfortable". I don't particularly care about acceleration, so to bring that down, I do plan on getting a freeway flyer, but I'm concerned that the bus won't have the grunt to use it effectively. Especially if I go all out w/ the widest gears and lowest R&P available...

I've seen some posts about Jake Raby's(now type4store's) Camper Special setup and that's intriguing, but there was also a post he did about a "super 2 liter" w/ a focus on economy. Key to that, seems to be to low RPMs, increase compression ratio, and coatings on most high speed friction surfaces.

Other than nikisil pistons, I haven't seen too much off-the-shelf(ie affordable) coated bearings so I suspect I won't be going down that path, which leaves RPMs and increased compression.

The RPMs will be dealt with w/ the transmission, but I think I need to increase torque pretty substantially to get the most. Increase compression should help.

Are there any guidelines for what comp ratios work well in a bus? It seems that even the CS keeps the CR down around 7(having trouble tracking down the exact number) which I appreciate the reasoning. But with precise fuel and spark control, temp and knock sensors, it seems like bumping that up _should_ be feasible.

Increased displacement would also help with torque, but much over 2L seems like reliability starts to be a concern. What's the consensus there?

And the CS pistons have a few options for diameter, but I don't see any options for increasing the relatively short stroke in a Type 4. Is anyone doing mild stroker cranks for the T4? What are the pros/cons there?


Thanks
-Tyler

[mrbell321]

Also, I think hydraulic lifters would be a pretty neat idea. Does anyone know if that's an option w/ CS heads? I pinged type4store, but no response in several days.

[wreck]

you'll need a 091 bus box , you still need revs to turn the fan to cool the heads at those engine loads particularly in a bus because of the wind resistance . A 96mm bore by 78mm stroke that is built properly will be just as reliable as a stock engine . Speak to EWM or Fat/Rimco about what you want and go from there.A good exhaust is also critical .

[mrbell321]

How much of a concern is the fan speed. I've been reading about it and there are differing options from "the fan only works at 4200rpm, anything else is worthless" to "the fan works fine in all conditions at all RPMs". Obviously neither of those is true...

78mm stroke would require case clearancing, yeah? And who makes a 78mm type 4 crank?

[raygreenwood]

The fan speed is not huge issue. Thats primarily a type 1 issue. You can bring the rpm range down to 3200-3400 rpm and have no cooling issues even with the brick of the bus. The type 4 fan puts out better static pressure. And no.... the fan does not ONLY "work" at 4200 rpm.

That is about where the fan stops working due to loading up to the point where it cavitates of slips without increasing cooling.

Yes.....I realize "most" but not all...of my type 4 experience is with 411 and 412 cars....but driving those at sustained 75 mph speeds in 100+ degree weather...with 500-700 lbs of equipment in a 2300 lbs car...with revs in the constant 3200-3300 range due to gearing....caused no overheating issues.

Its the gearing and tire size that affect this.

Bear in mind though....a top gear that drops rpm or a final drive that does the same with one through four staying stock....is going to be a driveability issue somewhere. Ray

[wreck]

.A well built and balanced engine will be happy to rev . with a box built with a 4.56 R&P and .82. 4th. will give you approx 75mph @ 3600 rpm . or a stock .89 4th will be 4000rpm . believe it or not you will get better economy at mid to high 3000 rpm range because that is most likely closer to where the engine makes it's peak torque. No clearancing needed for a 78mm stroke . I've a 78x103 engine in a Ghia that has spent hours sitting on 3600 to 4000 driving to shows and race meets .
An interesting article on type 1 fans that puts a lot of myths to bed
http://www.offroadvw.net/tech/wes/fan.html

[mrbell321]

I was thinking maybe a 3.88 R&P w/ the .88 4th. That gives almost the same 4th gear overall ratio, but less of a drop from 3rd-4th. It puts 75mph at about 3400 rpm in the Bus which, conveniently, is peak torque on a stock motor.
Yeah, it'll stretch 1-3 a bit, but if I can build the torque monster I'd like, that really shouldn't be a problem. Should seem fairly relaxed, unlike the stock 5.4(or whatever it is...) R&P which runs through first almost before you can let all the way off the clutch!

My main concern is that by my calculations 75mph will take about 40hp to push through the air. Add mech drag, weight, gradient, etc. will push that to 50hp almost without question. Stock peak torque at works out to about 50hp. I don't envy the cruising flat out, so I'm hoping to bump the torque up at least 15%... how deep are my pockets?

[64 sunroof]

My 1970 Bay westy has my old beetle type 4 engine (1700 type 4 with twin 40's build in the 90's with a dyno sheet showing 79 hp) on a 5 rib gearbox and it will cruise quite happily at 70 mph on the sat nav at around 4200 rpm I used to run taller tyres and obviously it dropped the RPM but i have struggled to find replacements for them (14" Goodyear Wrangler AT's ) so i just run normal 185r14 for the moment, I have previously bracket raced my camper (broke my racecar) and have managed a 20.9 second pass in the camper.

[mrbell321]

It is not really a matter of going a particular speed. I _can_ cruise at 75 pretty easily... it's just earsplittingly loud(the whole body seems to reverberate w/ the engine above ~4000rpm in any gear) and gets not so good mileage. I can't fill my tank all the way, so my numbers are pretty imprecise, but it seems to be only about 15mpg.
My goal is to lower the RPM, not increase speed. Mid-3k RPM should get the engine out of the resonant frequency of the body, plus just be quieter at a lower RPM.
As for MPG, friction losses are a cubic function of speed and pumping losses is largely pulling air passed a partially closed throttle. The lower RPM, the lower piston, crank, camshaft, valve, etc speeds provide _significantly_ lower frictional losses. There will be lower pumping losses If the throttle has to be opened wider to maintain that speed. Additionly, it should be running nearer maximum peak torque which is where the engine is most efficient at converting fuel to motion. I'm not sure about the function there, tho, but I can't work out a way that it would be bad(except for heat).

I"m also considering trying to retrofit an EGR system(to reduce pumping losses and lower head temps), but I think that will be a project for another day.

[raygreenwood]

It is not really a matter of going a particular speed. I _can_ cruise at 75 pretty easily... it's just earsplittingly loud(the whole body seems to reverberate w/ the engine above ~4000rpm in any gear) and gets not so good mileage. I can't fill my tank all the way, so my numbers are pretty imprecise, but it seems to be only about 15mpg.
My goal is to lower the RPM, not increase speed. Mid-3k RPM should get the engine out of the resonant frequency of the body, plus just be quieter at a lower RPM.
As for MPG, friction losses are a cubic function of speed and pumping losses is largely pulling air passed a partially closed throttle. The lower RPM, the lower piston, crank, camshaft, valve, etc speeds provide _significantly_ lower frictional losses. There will be lower pumping losses If the throttle has to be opened wider to maintain that speed. Additionly, it should be running nearer maximum peak torque which is where the engine is most efficient at converting fuel to motion. I'm not sure about the function there, tho, but I can't work out a way that it would be bad(except for heat).

I"m also considering trying to retrofit an EGR system(to reduce pumping losses and lower head temps), but I think that will be a project for another day.

You do not mean EGR. EGR is California driven.... intake manifold crapping...junk.

I think you mean..."PCV" system. Positive crankcase ventilation.....and the PCV system the factory put onto the 1.7 and 2.0L type 4 engines in the 411/412/914 cars....is hands down better than ANY PCV system I have seen anywhere in any of the forums..or on any car short of very modern.

It is a "pull through" system. It pulls fresh, cool, filtered in from the air cleaner, through a flame trap.....into the tops of the rocker boxes...pulls through the pushrod tubes pulling a lot of oil and any vapors with it...through the case picking up gasses...and out the cast in Z-baffel in the case top...through the oil baffle in the chimney...and through the PCV valve into direct manifold vacuum. Awesome. Ray

[mrbell321]

You do not mean EGR. EGR is California driven.... intake manifold crapping...junk.

I think you mean..."PCV" system. Positive crankcase ventilation.....and the PCV system the factory put onto the 1.7 and 2.0L type 4 engines in the 411/412/914 cars....is hands down better than ANY PCV system I have seen anywhere in any of the forums..or on any car short of very modern.

It is a "pull through" system. It pulls fresh, cool, filtered in from the air cleaner, through a flame trap.....into the tops of the rocker boxes...pulls through the pushrod tubes pulling a lot of oil and any vapors with it...through the case picking up gasses...and out the cast in Z-baffel in the case top...through the oil baffle in the chimney...and through the PCV valve into direct manifold vacuum. Awesome. Ray

Uhg...
Actually, I do mean egr. Not to discount pcv, but characterising egr the way you do... We're just going to disagree.

[Type 4 Unleashed]

I"m also considering trying to retrofit an EGR system(to reduce pumping losses and lower head temps), but I think that will be a project for another day.

So, you think pumping hot exhaust gases back into the cylinders is going (to reduce pumping losses and lower head temps) . All your going to do is further reduce the efficiency of the combustion cycle. EGR's are smog components, used to reduce emissions. So when you reduce the efficiency of the combustion cycle, you lose HP & Torque.

[mrbell321]

So, you think pumping hot exhaust gases back into the cylinders is going (to reduce pumping losses and lower head temps) . All your going to do is further reduce the efficiency of the combustion cycle. EGR's are smog components, used to reduce emissions. So when you reduce the efficiency of the combustion cycle, you lose HP & Torque.

Putting inert gases into the combustion chamber While cruising in place of oxygen reduces pumping loses which means increased efficiency and overall lower combustion temperature. Lower temps are how reduced emissions are accomplished.
EGR is not(or should not be) used during acceleration so peak hp and torque are not affected.

[Type 4 Unleashed]

So, you think pumping hot exhaust gases back into the cylinders is going (to reduce pumping losses and lower head temps) . All your going to do is further reduce the efficiency of the combustion cycle. EGR's are smog components, used to reduce emissions. So when you reduce the efficiency of the combustion cycle, you lose HP & Torque.

Putting inert gases into the combustion chamber While cruising in place of oxygen reduces pumping loses which means increased efficiency and overall lower combustion temperature. Lower temps are how reduced emissions are accomplished.
EGR is not(or should not be) used during acceleration so peak hp and torque are not affected.

What makes you think putting HOT inert gases that were just pumped out of the motor back into the combustion chamber (At Any Time) while cruising in place of oxygen reduces pumping loses which means increased efficiency and overall lower combustion temperature ?

With the reduction of oxygen as your saying it, is in fact is the contamination of the oxygen that came in the intake charge, so now the contaminated oxygen isn't sufficient enough to burn all the fuel that came in the intake charge. But you think that will reduce pumping loses and increase efficiency, never going to happen, your 50 hp motor just went to 35hp, where is the efficiency in that.

Then your other statement: The lower RPM, the lower piston, crank, camshaft, valve, etc speeds provide _significantly_ lower frictional losses. So what your saying for example: Is, the valve spring pressure which provide frictional losses have less spring pressure at say 3,000 rpm than they would at say 5,000 rpm, And I thought the 300 pds of spring pressure over the nose which is what the cam calls for is constant, unless there's a new variable rate valve spring that gives less pressure at lower rpm speeds and then the pressure increases as the rpm increase. I think there's something like that in Formula 1.

What reduce frictional losses are: Smaller rods and mains, lighter drive train components, so less spring pressure is required, less piston ring tension, less component mass. Lower rpm's do not reduce frictional losses', if you have a flat tappet cam that requires springs with 375 pds over the nose you'll have a certain amount of frictional loss, that same cam but now a roller cam that allows the roller to provide less friction than the flat tappet cams does, but you lose that gain now because the roller cam requires springs with 650 pds of pressure over the nose. Have you ever tried to turn over a V-8 motor with 16 springs each with 650 pds open pressure.

Build what you want, if you want to pump hot exh gases back into the motor, have at it.

[mrbell321]

What makes you think putting HOT inert gases that were just pumped out of the motor back into the combustion chamber (At Any Time) while cruising in place of oxygen reduces pumping loses which means increased efficiency and overall lower combustion temperature ?

With the reduction of oxygen as your saying it, is in fact is the contamination of the oxygen that came in the intake charge, so now the contaminated oxygen isn't sufficient enough to burn all the fuel that came in the intake charge. But you think that will reduce pumping loses and increase efficiency, never going to happen, your 50 hp motor just went to 35hp, where is the efficiency in that.

Egr gas does go past the carb and should be tuned out for EFI so there is no excess oxygen. The fuel is not metered for that part of the charge.
Remember this is for part throttle so your throttle plat has already turned your 50 HP motor into 35 hp. The benefit of egr is that your 35 HP motor is behaving as a 35 HP motor instead of a 50hp motor fighting itself.

Then your other statement: The lower RPM, the lower piston, crank, camshaft, valve, etc speeds provide _significantly_ lower frictional losses. So what your saying for example: Is, the valve spring pressure which provide frictional losses have less spring pressure at say 3,000 rpm than they would at say 5,000 rpm, And I thought the 300 pds of spring pressure over the nose which is what the cam calls for is constant, unless there's a new variable rate valve spring that gives less pressure at lower rpm speeds and then the pressure increases as the rpm increase. I think there's something like that in Formula 1.

no no no no... It's nothing to do with spring pressure, but oil sheer viscosity, often called wet friction. It's similar to what makes oil filled dampers work, but the more friction surfaces coated with oil, the more oil sheer viscosity you must deal with. And the power to overcome sheer increases with velocity

What reduce frictional losses are: Smaller rods and mains, lighter drive train components, so less spring pressure is required, less piston ring tension, less component mass. Lower rpm's do not reduce frictional losses', if you have a flat tappet cam that requires springs with 375 pds over the nose you'll have a certain amount of frictional loss, that same cam but now a roller cam that allows the roller to provide less friction than the flat tappet cams does, but you lose that gain now because the roller cam requires springs with 650 pds of pressure over the nose. Have you ever tried to turn over a V-8 motor with 16 springs each with 650 pds open pressure.

Build what you want, if you want to pump hot exh gases back into the motor, have at it.

just to be nit picky, less mass will do more than reduce frictional losses. Primarily it reduces inertial losses since there is so much reciprocating motion.

And egr is not a controversial science. It's been in common use for at least 40 years and motors are making more power with less fuel and fewer emissions than ever. If you've got a problem with it, you might have a problem with reality.