Planning for the future: engine advice

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mrbell321
Posts: 6
Joined: Thu Feb 08, 2018 3:30 pm

Planning for the future: engine advice

Post by mrbell321 » Tue Oct 09, 2018 5:32 pm

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
Posts: 6
Joined: Thu Feb 08, 2018 3:30 pm

Re: Planning for the future: engine advice

Post by mrbell321 » Wed Oct 10, 2018 9:15 am

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
Posts: 210
Joined: Thu Aug 14, 2014 2:07 am
Location: Brisbane Australia

Re: Planning for the future: engine advice

Post by wreck » Wed Oct 10, 2018 4:52 pm

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 .
No matter where you go , there you are !

mrbell321
Posts: 6
Joined: Thu Feb 08, 2018 3:30 pm

Re: Planning for the future: engine advice

Post by mrbell321 » Fri Oct 12, 2018 9:15 am

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?

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raygreenwood
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Re: Planning for the future: engine advice

Post by raygreenwood » Fri Oct 12, 2018 1:27 pm

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
Posts: 210
Joined: Thu Aug 14, 2014 2:07 am
Location: Brisbane Australia

Re: Planning for the future: engine advice

Post by wreck » Fri Oct 12, 2018 5:07 pm

.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
No matter where you go , there you are !

mrbell321
Posts: 6
Joined: Thu Feb 08, 2018 3:30 pm

Re: Planning for the future: engine advice

Post by mrbell321 » Sun Oct 14, 2018 5:35 pm

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
Posts: 22
Joined: Wed Mar 05, 2008 3:35 am

Re: Planning for the future: engine advice

Post by 64 sunroof » Tue Oct 16, 2018 6:35 am

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.Image

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