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Dangermouse
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Joined: November 23, 2005
Posts: 1266
Location: Beautiful New Zealand
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BruceJ
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Joined: June 16, 2009
Posts: 236
Location: Portland, ME
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 Posted: Wed Jan 15, 2014 9:19 am Post subject: |
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Looks like it's been a while on this thread but this is useful for me now as I'm considering the doghouse conversion for my own 40-horse rebuild.
Question: Which (if any) engine tin pieces will I have to change, going from my stock fresh air 40-horse? |
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KTPhil 
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Joined: April 06, 2006
Posts: 34003
Location: Conejo Valley, CA
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| Posted: Wed Jan 15, 2014 11:34 am Post subject: |
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| Just the top shroud stuff. The lower stuff is the same. Be sure the right size fan and Hoover Bit are included. |
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BruceJ
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Joined: June 16, 2009
Posts: 236
Location: Portland, ME
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| Posted: Wed Jan 15, 2014 12:52 pm Post subject: |
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| KTPhil wrote: |
| Just the top shroud stuff. The lower stuff is the same. Be sure the right size fan and Hoover Bit are included. |
Ok, cool -- that's what I was hoping. Still, some parts vendors seem to differentiate at least one tin piece, like this one: http://www.jbugs.com/category/vw-front-engines-tins.html
Regardless, it seems to me that unless your going 100% show/vintage, for a relatively small cost you could have much improved cooling and durability. Except for the upfront costs, no downside I can see. |
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vwsteve
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Joined: March 18, 2004
Posts: 1047
Location: Virginia
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| Posted: Wed Jan 15, 2014 6:39 pm Post subject: |
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| I converted my big bore 40 to doghouse. It actually ran hotter with the deck lid completely closed. After I used the tennis ball trick, it runs cooler than ever. VW added cooling vents when they went doghouse. |
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jzjames
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Joined: September 27, 2007
Posts: 1921
Location: Windy Point, WA
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| Posted: Wed Jan 15, 2014 7:10 pm Post subject: |
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[quote="BruceJ"]
| KTPhil wrote: |
Regardless, it seems to me for a relatively small cost you could have much improved cooling and durability. Except for the upfront costs, |
This thread has got me thinking about this, it does seem like it might be an improvement, and a worthwhile upgrade.
HOW worthwhile is the question. Will it extend the life of a 40 hp motor!?? |
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BruceJ
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Joined: June 16, 2009
Posts: 236
Location: Portland, ME
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| Posted: Wed Jan 15, 2014 8:45 pm Post subject: |
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| vwsteve wrote: |
| I converted my big bore 40 to doghouse. It actually ran hotter with the deck lid completely closed. |
How'd that happen, do you figure? Is there something inherent in the doghouse setup that will, say, let heat build up elsewhere that must in turn be vented, or else it's drawn right back into the fan and you have a sort of positive feedback loop? |
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KTPhil
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Joined: April 06, 2006
Posts: 34003
Location: Conejo Valley, CA
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| Posted: Wed Jan 15, 2014 9:28 pm Post subject: |
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My 40HP (bored to 1385cc) ran FAR cooler with the doghouse. Non-scientific comparison following the same long freeway drive:
before: dipstick too hot to handle at all, can't even pull it out without a glove
after: pull it out, grip it without pain.
It also ran better with the doghouse after that freeway run, since it was so much cooler. You could tell by better low-rpm acceleration and idle stability at the end of an offramp.
1600 engines with doghouse may need more air, but I never found a problem with a 1200/1385.
Last edited by KTPhil on Sat Jan 18, 2014 11:09 am; edited 2 times in total |
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Eric&Barb
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Joined: September 19, 2004
Posts: 24733
Location: Olympia Wash Rinse & Repeat
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| Posted: Wed Jan 15, 2014 9:58 pm Post subject: |
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| BruceJ wrote: |
| vwsteve wrote: |
| I converted my big bore 40 to doghouse. It actually ran hotter with the deck lid completely closed. |
How'd that happen, do you figure? Is there something inherent in the doghouse setup that will, say, let heat build up elsewhere that must in turn be vented, or else it's drawn right back into the fan and you have a sort of positive feedback loop? |
Non-dog house all cooling air thru the oil cooler goes right on to cool the #3 & 4 cylinders.
In dog house set up the air that cools the oil cooler is dumped out the front of the engine tin. To do this VW had to increase crankshaft pulley size to bigger than any pulley since the 40 HP engine came out in 1961. Bigger pulley equals more gen and cooling fan RPM, which in turn means more cooling air pumped thru the shroud.
Plus the dog house cooling fan started out with 33 mm, then went to 34 mm, and ended up with 35 mm wide inside measurement. Wider means even more cooling air pumped thru the shroud.
Widest non-dog house cooling fan was 29mm.
VW up till 1969 did not put in vents in the rear Beetle engine lid except for the cabriolet which had no vents above the lid due to the top design.
1970-71 sedans the lids have two set of vents and 1972-79 had four sets of vents.
So having a pre-1970 Beetle non-cabriolet with out any vents in the engine lid can cause less air to be able to be sucked into the engine compartment, which can cause the engine to have a cooling problem. For the pre-1968 VWs one can just add a tennis ball under the lid to allow air to be sucked in and/or add a cabriolet vented lid.
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Chuey
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Joined: October 18, 2010
Posts: 855
Location: Oceanside, California
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| Posted: Wed Jan 15, 2014 11:29 pm Post subject: |
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I always wonder what is going on when I read about people who have overheating problems with bugs. I've never had that. I've owned a couple of 64s and a 69 and a 70. Also, several buses, but this is about bugs so I'll stick to that.
If all the tinware is in place and in good condition, stock transaxle ratios, close to stock size tires, I don't get how people end up with overheating. I've driven my bugs through all kinds of weather and a lot of it very hot. I've never lost a valve and I don't re-do my heads except if the engine is being rebuilt. Also, I have tended to drive the forty horse engines (current one is 1385) pretty much wide open much of the time and lots of that on Southern Calif. freeways. In other words, I don't baby my VWs.
I'm not saying folks shouldn't use a dog house on a forty horse. I'm just wondering why I read about folks having overheating?
Chuey |
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Eric&Barb
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Joined: September 19, 2004
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Location: Olympia Wash Rinse & Repeat
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| Posted: Thu Jan 16, 2014 7:26 am Post subject: |
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Well the issue with these ACVW engines is over heating is an insidious problem. After all, there is no water to boil and steam up to show one is overheating.
If one runs oil temp and pressure gauges you can easily notice the changes in the engine.
Got our 1960 panel camper for free and ran big bore 40 HP engines in it that other than the P&Cs were totally stock. Found the transaxle in it was way too low geared and found a stock geared one to run instead.
Only after running a couple of engines into the ground were they would not climb same hill at same MPH after about 30,000 miles, installed gauges and found oil temp was hitting 280 F @ 3,800 RPM in third gear going up steep hills in N. California. BIG EYE  opener that was.
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KTPhil
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Joined: April 06, 2006
Posts: 34003
Location: Conejo Valley, CA
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| Posted: Thu Jan 16, 2014 8:52 am Post subject: |
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| Chuey wrote: |
I always wonder what is going on when I read about people who have overheating problems with bugs. I've never had that. I've owned a couple of 64s and a 69 and a 70. Also, several buses, but this is about bugs so I'll stick to that.
If all the tinware is in place and in good condition, stock transaxle ratios, close to stock size tires, I don't get how people end up with overheating. I've driven my bugs through all kinds of weather and a lot of it very hot. I've never lost a valve and I don't re-do my heads except if the engine is being rebuilt. Also, I have tended to drive the forty horse engines (current one is 1385) pretty much wide open much of the time and lots of that on Southern Calif. freeways. In other words, I don't baby my VWs.
I'm not saying folks shouldn't use a dog house on a forty horse. I'm just wondering why I read about folks having overheating?
Chuey |
My commute included going through Newhall Pass, and trying to maintain freeway speeds among the road ragers meant pedal to the metal. Then a combo of jackrabbit starts at lights, then long idling, in boulevard traffic. Back then gas was shitty as well, since unleaded was a recent mandate. That combo meant I was working the girl pretty hard. The doghouse meant a world of difference for temps and engine life.
There is some difference, too, between the coast at 75 and the valleys/deserts over 100.
That said, it should not be used to mask another cause of overheating like low compression or poor state of tune (ignition or carburation). |
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BruceJ
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Joined: June 16, 2009
Posts: 236
Location: Portland, ME
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| Posted: Sat Jan 18, 2014 9:35 am Post subject: |
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| Quote: |
| The doghouse meant a world of difference for temps and engine life. |
So, just to be sure -- on your 1385, no tennis ball, no deck lid vents? As I'm currently building up a 1385 myself, I want to make sure. I hear what's said about it not being necessary, and if I was already up and running without problems I wouldn't mess with it, but since I'm starting from scratch, I figure it's a good thing to consider. |
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KTPhil
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Joined: April 06, 2006
Posts: 34003
Location: Conejo Valley, CA
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| Posted: Sat Jan 18, 2014 11:14 am Post subject: |
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Right, but also keep in mind that I had first brought the car back to a stock carb, muffler, and distributor. Another point is that the big bore kit meant a higher compression ratio, and with the bad gas of the era, I had added shims under the barrels to get back to only a tenth or so higher than the stock compression ratio.
All this was done before I installed the doghouse setup. It was maybe a year after the rebuild that I wanted more cooling.
Lastly, my driving style was flat out but not over-revving... others that are often at redline might have more airflow needs than my typical driving. Full throttle, yes, but I was almost never at redline in high.
All this said, the doghouse is a great idea. Combine it with a stock thermostat, properly adjusted and checked at tune-ups, and your engine will spend more of its life at moderate temps, neither too hot not too cold. That's gotta make it last longer!
Last edited by KTPhil on Sun Jan 19, 2014 12:57 pm; edited 1 time in total |
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BruceJ
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Location: Portland, ME
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| Posted: Sun Jan 19, 2014 6:16 am Post subject: |
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| Okay cool (pun intended)! Thanks for all the input. |
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bluebus86
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Posts: 11075
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| Posted: Sun Jan 19, 2014 7:14 pm Post subject: |
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you may need to add some cooling air to the engine bay with the bigger fan that the dog house uses. remember that VW added cooling louvers in the later bugs, in part because the fan draws more air, in part because the engine draws more air. keep in mind the later cars were geared to lower engine rpms, the stock tranny that you should have will like to rev that bigger fan more.
when I put a stock 1973 1600 DP in my 61 bug, I found that at freeway speeds (stock 61 gearing) that my engine was starved for air, until I propped open the bottom of the deck lid with some spacers, that stopped the starving for air at high speeds, and reduced my air temperature.
I am not sure if this is required for you, as you are only upgrading the fan, I upgraded the fan and engine displacement.
so do some tests at high speed, see if she bogs down if she does , then prop open the deck lid and see if things improve. oil or head temp gages will also help tell if you should prop open the deck lid. Of course you can add louvers or find a rare convertible deck lid that has louvers for your year of car
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vwsteve
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Joined: March 18, 2004
Posts: 1047
Location: Virginia
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| Posted: Sun Jan 19, 2014 7:33 pm Post subject: |
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| KTPhil wrote: |
1600 engines with doghouse may need more air, but I never found a problem with a 1200/1385. |
The doghouse setup flows more air. A solid deck lid will be the bottleneck. The older cars were geared lower meaning the cooling fan will be spinning even faster at the same mph. For this reason, the extra vents are needed more for the older cars running doghouse. I don't doubt that you never had an overheating problem, but if you want to make the most of the doghouse, you need the added vents (or standoffs or tennis ball).
I use the tennis ball on mine, except when very cold out, and it makes a world of difference. |
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KTPhil
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Posts: 34003
Location: Conejo Valley, CA
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| Posted: Sun Jan 19, 2014 8:35 pm Post subject: |
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| vwsteve wrote: |
| KTPhil wrote: |
1600 engines with doghouse may need more air, but I never found a problem with a 1200/1385. |
The doghouse setup flows more air. A solid deck lid will be the bottleneck. The older cars were geared lower meaning the cooling fan will be spinning even faster at the same mph. For this reason, the extra vents are needed more for the older cars running doghouse. I don't doubt that you never had an overheating problem, but if you want to make the most of the doghouse, you need the added vents (or standoffs or tennis ball).
I use the tennis ball on mine, except when very cold out, and it makes a world of difference. |
Even in 100+ weather, I never overheated with the DH. Never ran so hot that I could not pull out the dipstick and hold it. So maybe other factors have an effect, too? That is one reason I mentioned that I brought it back to stock configuration first, and spent very little time at or near redline. |
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doug spencer
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Joined: May 31, 2016
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Location: Dallas,Tx.
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| Posted: Sun Jul 24, 2016 7:50 pm Post subject: Re: Going doghouse on the 40hp ? |
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| Just had a 1641 installed into my '64 Type 1.I understand the need for more fresh air with the the DH.I don't really like the look of hinge extensions or the tennis ball. Is anyone reproducing vented deck lids,made of metal, not fiberglass or carbon fiber?Can metal shops put louvers in my existing hood? will a '64 convertible deck lid work? The tennis ball may be temporary solution for now.All of the seals and tins are in place. Being in central Texas in the throes of a heat wave, I'm afraid to drive during the day. the engine has only 10 or so miles on it at this point,a proper breaking at this point is my foremost concern, a vented deck lid being next. I 'd appreciate tips and advice,the is my first VW. |
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mukluk
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Joined: October 18, 2012
Posts: 7023
Location: Clyde, TX
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| Posted: Sun Jul 24, 2016 8:36 pm Post subject: Re: Going doghouse on the 40hp ? |
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| doug spencer wrote: |
| Just had a 1641 installed into my '64 Type 1.I understand the need for more fresh air with the the DH.I don't really like the look of hinge extensions or the tennis ball. Is anyone reproducing vented deck lids,made of metal, not fiberglass or carbon fiber?Can metal shops put louvers in my existing hood? will a '64 convertible deck lid work? The tennis ball may be temporary solution for now.All of the seals and tins are in place. Being in central Texas in the throes of a heat wave, I'm afraid to drive during the day. the engine has only 10 or so miles on it at this point,a proper breaking at this point is my foremost concern, a vented deck lid being next. I 'd appreciate tips and advice,the is my first VW. |
I'm not aware of anybody making a metal vented decklid for 58-67 Beetles, but a decent body shop should be able to graft in the louvers from a vented decklid. Additionally, yes, a convertible decklid would work as well if you can find one and don't mind the asking price.
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