Steps to scratch build a VW

Help Support HomeBuiltAirplanes.com:

TFF

Well-Known Member
Well go all in. I say a Cummings diesel with with model airplane jet engines blowing the turbos so the exhaust can be full flow. That or five Briggs 5 hp motors on a ring mount so it looks like a radial and all geared to a center prop shaft. Those are double dog dares.

Pops

Well-Known Member
HBA Supporter
Log Member
I had 1 1/4" OD X .035 wall, I really wanted 1 1/4" ID but couldn't find any.

Little Scrapper

Well-Known Member
HBA Supporter
Log Member
Well go all in. I say a Cummings diesel with with model airplane jet engines blowing the turbos so the exhaust can be full flow. That or five Briggs 5 hp motors on a ring mount so it looks like a radial and all geared to a center prop shaft. Those are double dog dares.
maybe clipped wings and put it on floats too?

TFF

Well-Known Member
No wings. Too much drag.

Vigilant1

Well-Known Member
Random thought: At my mile high airport, my 2180 makes about the same power as the 1835 does at sea level. Does that make it as reliable as an 1835?
My unvalidated thoughts:
-- I'd say it is close. If you ask for only 60 HP from a 2180, it will avoid most problems people experience with them.
-- If we've got your 2180cc at 6000'MSL and the 1835cc at SL, both making 60HP, the 1835cc benefits from thicker air to carry away heat faster from the fins. So, likely lower CHTs for the 1835cc, which is an advantage. But, with normal adiabatic cooling with altitude, the difference is mitigated-- a little. Advantage goes to the 1835 at SL.
-- Stroker = higher piston speeds = more stress on conrods, the case/bearing saddles, etc. So, depending on RPM, advantage likely goes to the 1835 at SL.

But, there's no doubt that a 2180 that isn't asked to make more than 60HP is likely to be happy for a long time.

n45bm

Active Member
I’m sitting with a new VW engine case in my shop from this thread. Would a VW engine be manageable in a Baby Ace. I believe the Pober Pixie was VW power as well as the Cignet and the FRED.

What do you guys think?
Here's a picture of a VW powered Baby Ace I found on the Corben Aircraft Facebook page.

Pops

Well-Known Member
HBA Supporter
Log Member
My unvalidated thoughts:
-- I'd say it is close. If you ask for only 60 HP from a 2180, it will avoid most problems people experience with them.
-- If we've got your 2180cc at 6000'MSL and the 1835cc at SL, both making 60HP, the 1835cc benefits from thicker air to carry away heat faster from the fins. So, likely lower CHTs for the 1835cc, which is an advantage. But, with normal adiabatic cooling with altitude, the difference is mitigated-- a little. Advantage goes to the 1835 at SL.
-- Stroker = higher piston speeds = more stress on conrods, the case/bearing saddles, etc. So, depending on RPM, advantage likely goes to the 1835 at SL.

But, there's no doubt that a 2180 that isn't asked to make more than 60HP is likely to be happy for a long time.
I need to get back on building the flywheel drive VW engine. Hard decision to make it a 1835 or 2180 cc. I did the Bob Hoover mods to the oil system, cleared the block for the 2180 crank , welded behind #3 cylinder. Have a set of single post heads drilled for lower spark plugs.
If I was to build SSSC-2 for the engine I could make it a 1835cc and get the same great performance of SSSC #1. But if I make it a 2180 cc engine I would still be able to run it at about 50/55% in cruise like the 1835 but have the little extra RPM for more rate of climb over the +1200 of the 1835cc engine if I wanted to use it. Or use the extra HP in increasing the pitch of the prop to 28" from the 26" and get a little more cruise speed, ( very little). Or keep the 26" pitch and just cruise at a little higher RPM.

Decisions, Decisions, Did I miss anything ?

Vigilant1

Well-Known Member
If I was to build SSSC-2 for the engine I could make it a 1835cc and get the same great performance of SSSC #1. But if I make it a 2180 cc engine I would still be able to run it at about 50/55% in cruise like the 1835 but have the little extra RPM for more rate of climb over the +1200 of the 1835cc engine if I wanted to use it.
Yep.
"I've already got some nice single port heads. Why pay for power I probably won't use much and will hardly ever need?"
Vs.
" But if 'hardly ever' knocks at the door, it'll be nice to stay out of the trees."
Vs
" You didn't need it on the last SSSC!"
Etc, etc.
The good news is that both engines are good and pretty cheap (as airplane parts go). Great options to have. With the experience you've got, you can't go far wrong.

ETA: If the plane was a new design or had significant modifications, there would be a good case for choosing more HP from the start.

Pops

Well-Known Member
HBA Supporter
Log Member
Yep.
"I've already got some nice single port heads. Why pay for power I probably won't use much and will hardly ever need?"
Vs.
" But if 'hardly ever' knocks at the door, it'll be nice to stay out of the trees."
Vs
" You didn't need it on the last SSSC!"
Etc, etc.
The good news is that both engines are good and pretty cheap (as airplane parts go). Great options to have. With the experience you've got, you can't go far wrong.

ETA: If the plane was a new design or had significant modifications, there would be a good case for choosing more HP from the start.
I keep going back to the long wing SSSC-2.
One time with the SSSC I needed all the ROC and more. Didn't check out the box canyon before flying into it. and was at max angle of climb speed and found a space between the tops of trees to go through to get over the ridge. The gap was about 20 degs to the left, eased in a little rudder and slid over to the gap in the trees. Told a friend that I was flying in that area. He said, you didn't fly up that box canyon did you ? He said he almost didn't get out.

simflyer

Well-Known Member
To get the most bang for the buck, and the most reliablity for the HP. Stock German 69 mm crank. Single port heads for more torque below 3000 rpm over dual port heads, with 1 1/4" dia intake tubes , stock cam and 92 cylinders and pistons for 1835 cc. Balance with 7.55 CR.
Nope, bore of 92mm needs machining of block and heads and short 69mm stroke needs higher - 3200-3600rpm, to get torque and power, which is devalved by short diametr of prop, cause of limiting tip speed to 850km/h.

Pops

Well-Known Member
HBA Supporter
Log Member
Nope, bore of 92mm needs machining of block and heads and short 69mm stroke needs higher - 3200-3600rpm, to get torque and power, which is devalved by short diametr of prop, cause of limiting tip speed to 850km/h.
Yes the case and heads needs to be machined for the 92 mm pistons and cylinders. The short (Stock) stroke of 69 mm will get good torque and power at 3000 rpm and below IF everything else is done for max torque at low rpm's.
This has been discussed many times on this site. Single port heads, smaller dia for the intake tubes. Intake designed for equal charge in each cylinder, etc.
I have posted this video several times on this site of my SSSC with a 1835 cc VW engine turning a Culver 60"x 26" prop at Full throttle of 3150-- 3200 rpm climbing at 1200+ fpm with my 235 lbs. Cruise of 2650-2700 rpm at 80 mph.
You don't put the 1835 cc engine in an airframe that requires 70 hp to stay in the air.

This is up hill take-off on 900' long grass field with tall trees on the end. Not a short prop ( 54") turning high RPM's.

simflyer

Well-Known Member
... The short (Stock) stroke of 69 mm will get good torque and power at 3000 rpm and below IF everything else is done for max torque at low rpm's.
... my SSSC with a 1835 cc VW engine turning a Culver 60"x 26" prop at Full throttle of 3150-- 3200 rpm climbing at 1200+ fpm with my 235 lbs. Cruise of 2650-2700 rpm at 80 mph.
This is up hill take-off on 900' long grass field with tall trees on the end. Not a short prop ( 54") turning high RPM's.
Pops, 88mm bore on 76mm stroke give higher torque at lower rpms than 92x69 and could use more effective 63-65" prop - recomended by Sauer. Then You surely climb better, than with 92x69mm and 60" prop.

Pops

Well-Known Member
HBA Supporter
Log Member
Pops, 88mm bore on 76mm stroke give higher torque at lower rpms than 92x69 and could use more effective 63-65" prop - recomended by Sauer. Then You surely climb better, than with 92x69mm and 60" prop.
Then you couldn't use the good stock German made crankshaft and pay more money for the stroker crank. Like I said, most bang for the $. Yes, I could go with a slightly longer prop and less pitch for a better ROC. It's also a balance in what I want in climb and cruise. I am cruising at 80 mph ( 2.9/3.0 GPH) at about 55% power and WOT is at about 95 mph, I could trade some ROC for a little more cruise, but very little . Then I could trade some of my cruise for a little more climb, but I like what I have, about the best of both. Vigilant1 Well-Known Member Lifetime Supporter If we went with 88 bore and 76mm stroke, would we also need the beefed-up Force One bearing and hub? That's often recommended for any stroker crank Type One, but is that still valid for bores as small as 88mm? If so, that's more machining and part$.
If going to the trouble of making a stroker, going with the larger bore seems like a "should do." No more weight, about the same cost at that point. After all, you don't have to push that throttle all the way in if you don't need it.

Last edited:

Pops

Well-Known Member
HBA Supporter
Log Member
If we went with 88 bore and 76mm stroke, would we also need the beefed-up Force One bearing and hub? That's often recommended for any stroker crank Type One, but is that still valid for bores as small as 88mm? If so, that's more machining and part\$.
If going to the trouble of making a stroker, going with the larger bore seems like a "should do." No more weight, about the same cost at that point. After all, you don't have to push that throttle all the way in if you don't need it.
According to Steve at GP's ( wish he was still with us), using any stroker crank larger than the stock 69 mm the Force One should be used. That is a big jump in the price of building an engine. I ask Steve about using the Force One when I was building this 1835 cc engine and he said it would just be a waste of money when using the stock crank and 92 or 94 pistons and cylinders.
The first 32 hrs on the SSSC, I had a little 1200 cc, 40 HP engine. Sweet little engine. I have another, a 1965, 1200 cc, 40 hp I'm putting in my pipe buggy with oversize 83 pistons and cylinders for 45 hp. Should get great mileage.

TFF

Well-Known Member
I believe Pops is trying to run his as close to the same stress horsepower to cubic inch as a certified engine. There are aerobatic planes turning their IO540s to 4000 rpm. They also have an engine sponsor and change engines at 500 hours.

You have to hedge it a little bit to be useable with a VW, but who do you think ends up with the best VW is experience. Pops running his at 45 hp or someone putting the smaller prop in the same engine to get the 60? The engine parts are the same; one is being forced out of its nature to put it in a box it really doesn’t fit in.

N804RV

Well-Known Member
HBA Supporter
I'm running a 52" prop (52/42) on my 1835 dual port. I see about 3,150rpm on takeoff. And, a little more than 3,300 WOT straight and level at SL. I can typically see 750fpm on climb out at 90kts.

I don't baby that engine. Tooling around the local area, I tend to keep it up around 3,200 RPM. And, I regularly do aerobatics. It has over 400hrs on it. And, it still purrs along. The builder swears it'll go to 1,000 and then some. I believe him.

This biggest concern I have is the heads. Those 8mm studs seem to have grown just the tiniest bit every time I check. I retorque the heads and change the oil every 25hrs. I'm sure if I wasn't doing this, the 3-4 head would have already failed by now. But, compression is still very good, the CHTs stay below 400, and it doesn't burn any oil. So, I must be living right.

I just recently flew it 400 miles round trip to Van's to pick up a small part for my RV-8 build. It purred like a kitten all the way. At 3100rpm and leaned out cruising at 4,500'msl, it burned slightly less than 3gph.

Last edited:

akwrencher

Well-Known Member
HBA Supporter
Based on fuel burn, it sounds like you are running it at about the same power level Pops did.

103

Well-Known Member
I'm running a 52" prop (52/42) on my 1835 dual port. I see about 3,150rpm on takeoff. And, a little more than 3,300 WOT straight and level at SL. I can typically see 750fpm on climb out at 90kts.

I don't baby that engine. Tooling around the local area, I tend to keep it up around 3,200 RPM. And, I regularly do aerobatics. It has over 400hrs on it. And, it still purrs along. The builder swears it'll go to 1,000 and then some. I believe him.

This biggest concern I have is the heads. Those 8mm studs seem to have grown just the tiniest bit every time I check. I retorque the heads and change the oil every 25hrs. I'm sure if I wasn't doing this, the 3-4 head would have already failed by now. But, compression is still very good, the CHTs stay below 400, and it doesn't burn any oil. So, I must be living right.

I just recently flew it 400 miles round trip to Van's to pick up a small part for my RV-8 build. It purred like a kitten all the way. At 3100rpm and leaned out cruising at 4,500'msl, it burned slightly less than 3gph.
Are you using the 4130 SCAT 8mm studs?

Matt

Pops

Well-Known Member
HBA Supporter
Log Member
The VW engine as a sweet spot at between 3000 and 3200 rpm. What RPM do you think the VW engine in the bug is turning when on the interstate at 60 mph with stock tires ? I will give you one guess

I have never had any problems with having to re-torque head bolts. If you do, the heads are running to hot.