Is It Spring Yet?

One more

I can’t think of anything else to tinker with. It’s dialed in!  Let the sun shine in!!!

Randy, the speedster looks great !! A bit of weak weather coming our way, but Spring is in the air. Hope to see you at the breakfast spot with the 356 bunch.

Dave

My car is in the cocoon still, unfortunately. But it will come out soon I think.

Man, that shinny red!  Ceramic coating?

In NW FL we are lucky to get a week or 2 of Spring!  It's like a toggle switch here - a few nice days with 70's and low humidity and then next day 85 and same humidity!  Not sure this year since we got that unprecedented 8-9" of SNOW!

Curious on predicted FL hurricane activity this year.  Insurance in all of FL (not just coastal properties) has increased 400%.  A recent article said insurance companies were raking $ in from FL and spreading the profit to other state locations!  1/3 of FL home owners are un-insured now.  Just too expensive.

No ceramic yet. I did use Zymol rouge wax on it last year but it’s probably all gone by now. That is just Signal Red paint, soap and water!

@Butcher Boy Dave, can you send me a note with details. I’m so glad yours is finally running better.

It took 5 months to get my Audi tranny sorted out, but it is finally done. Only $4k total but TONS of hassles. It turns out you can’t replace an Audi transmission without Audi permission from Germany. It locks the donor transmission!  Insane. You have to satisfy them it’s not stolen — finally done somehow.

WIt my Audi gone, I drove the Speedster a lot more than expected this winter — not exactly daily driver, but much more than I would have normally.

The other huge non-Speedster news is that I built the audiophile system of my dreams. Off topic for sure, but it kept me busy. Vandersteen, Ayre, Aurender, Benchmark (and Samsung Frame to boot). All the fixins. I rebuilt the dresser to be an open back stereo cabinet to hide all the invisible pieces. Getting old has its advantages…

Randy....I really like your sound system.  I'm sure the sound quality is excellent !  My hearing has gone on to someone else I expect.  So a JBL Charge 3 in my car sounds pretty good ! ha ha !  My Speedster was about the same color of red.  Even now, when I look at some photos,  I smile.  It still looks beautiful to me........Bruce

@aircooled Hey, Bruce.

Aurender N10 Server

Benchmark DAC3 B dac

Ayre KX-R preamp

Ayre VX-5 Twenty amp

Vandersteen Quatro

The preamp is the jewel.  Almost as much as everything else put together!  Solid aluminum machined block!  I usually try to cobble together a miracle out of bargain this and that.  I chose to cut no corners on the Speedster and the stereo.  I just bit the bullet.  Both turned out great….

Signal colors from Porsche were always my favorites.  Signal Orange on early 911s…. I almost did silver with deep red interior for the Speedster like another contributor here ( @JoelP ), but red just called to me.

@Teammccalla- Love the converted dresser!  A couple more pics, please?                          Is the Odyssey battery normal or motorcycle/tractor size in your Speedster (which, btw, looks GREAT!)?  Where is it located and what cables do you have running to and from?  And do you know the specs (cam/rockers, heads and valve sizes, exhaust, compression, carbs, how high it revs with power- you know, the good stuff!) on your 2332?  Transaxle r&p and gearing?

My apologies for all the questions if you've detailed this elsewhere- give me a link to the post and I'll go back and look it up.  Al

Engine first:  

I have a 2332 T1 in a 2023 VMC.  The bottom end is Pat Downs VMC stock.  I had the top end rebuilt by a local shop Pat Downs recommends with a set of his custom dual spring heads and manifolds. And all the performance goodies.  My carbs are brand new Dell’Orto DRLA 40s.  I had them rebuilt by Rick Hunt even though they were new, just to make sure everything was fresh.  

It’s completely ”drivable” and pulls strongly to about 5500.  When I’m running hard, I shift at 5000.  HP, who knows…. I gave some HP up to tune it to a smooth runner.  It’s still a little rich but it’s got plenty.  I’d say it feels “quick” by modern standards, which is as far as I want to push it with my other equipment.  Its just meant to be quick and fun, not a real performance car.

So here is the summary:

A-1 sidewinder
NOS Dellorto 40 DLRAs from Rick Hunt
”Mild” VMC cam
94mm cylinders And Mahle Motorsports 94mm piston kit
Compression 9.5:1 (not 8.2:1 as reported in VMC literature)
1.25 Rocker arm kit with swivel ball adjusting screws
Custom Pat Downs heads.  AA 500 series cylinder heads with 40x35.5 stainless valves, D port intake, dual valve springs, chromoly retainers, 94mm bore
IDF port matched manifolds to cylinder heads done by Pat
Chromoly .035 wall push rods, racing push rod tubes, push rod tube seal kit
Replica Carrera air cleaners
Pat Downs welded fan
3:44 R&P stock VMC
Kennedy stage 1 clutch

@Teammccalla posted:

Getting old has its advantages.

Yeah, like Bruce said, nothing sounds any better (or worse*) than my JBL earbuds and MP3s. After 30 years doing sound and driving/riding convertibles and motorcycles, my hearing is probably 50% of what it was in my teens.

My son put his good stereo stuff into an early 60’s MCM console stereo cabinet. Looked so cool.

* That may be an exaggeration. I can tell the difference when my home theater amp auto switches between analogue Dolby 5.1 and whatever spec the digital HD channels broadcast in.

@ALB

The battery is an Odyssey PC680.  Stock VMC cables.  No extra grounds.  My battery is in the standard front box.  Any advice welcome.

I’d say it works (barely adequately) so far with the IMI-101 starter.  I’d like it to be stronger still.  I’m going to try it for awhile, especially when weather gets hot.

Which makes me remember, I want better cooling!  It gets hot, close to overheating sometimes. I think moving the cooler to the front is in my future.  I might look at an upgraded cooler too?  

@dlearl476 posted:

Yeah, like Bruce said, nothing sounds any better (or worse*) than my JBL earbuds and MP3s. After 30 years doing sound and driving/riding convertibles and motorcycles, my hearing is probably 50% of what it was in my teens.

My son put his good stereo stuff into an early 60’s MCM console stereo cabinet. Looked so cool.

* That may be an exaggeration. I can tell the difference when my home theater amp auto switches between analogue Dolby 5.1 and whatever spec the digital HD channels broadcast in.

Everyone can hear the difference with my system.  Mom looked at it puzzled for awhile and said, wow, that’s nice.  She has no interest in such things usually.  88 year old dad had a similar curious reaction, and he’s hard to impress.  Vandersteen and Ayre are a different league than I’ve ever heard, and I’ve toyed with audio for 30 years.  Get yourself one!

@Teammccalla posted:

No ceramic yet. I did use Zymol rouge wax on it last year but it’s probably all gone by now. That is just Signal Red paint, soap and water!

FWIW, i swore off wax and elbow grease last year after a guy on another forum posted about a tech demo his PCA chapter had with the guys fromThe Rag Company. I’ve been using their Optimum NoRinse and Opti-Coat HyperSeal ever since. Twice the results and 1/10th the effort.

@ALB

I can take some more pics but here are a few.  Looks like spaghetti but everything is shielded and crossing at 90 degrees, etc.

@WOLFGANG posted:

Man, that shinny red!  Ceramic coating?

In NW FL we are lucky to get a week or 2 of Spring!  It's like a toggle switch here - a few nice days with 70's and low humidity and then next day 85 and same humidity!  Not sure this year since we got that unprecedented 8-9" of SNOW!

Curious on predicted FL hurricane activity this year.  Insurance in all of FL (not just coastal properties) has increased 400%.  A recent article said insurance companies were raking $ in from FL and spreading the profit to other state locations!  1/3 of FL home owners are un-insured now.  Just too expensive.

What is the plan for these 1/3 of non insured Fl homeowners when things turn bad? Whine for the Federal government to help them? Few people can afford to be self insured.

@Teammccalla posted:

@ALB

The battery is an Odyssey PC680.  Stock VMC cables.  No extra grounds.  My battery is in the standard front box.  Any advice welcome.

I’d say it works (barely adequately) so far with the IMI-101 starter.  I’d like it to be stronger still.  I’m going to try it for awhile, especially when weather gets hot.

Which makes me remember, I want better cooling!  It gets hot, close to overheating sometimes. I think moving the cooler to the front is in my future.  I might look at an upgraded cooler too?  

Guys here have had success replacing the battery cables with (#4? #2?) welding cable.  Hopefully someone who's done it will add their 2 cents.  If the auxiliary oil cooler is in the rear left fender well and is thermostatically controlled I don't see much benefit in moving it (with it's much longer lines and increased demand on the pump) to the front.  I know that's how Porsche did it, but a cooler in the fender well receives ample airflow, and with the oil lines being much shorter there's not nearly as much friction (and friction = heat).  Anyone I know, personally or online, that's run a high hp Type 1 engine successfully on the street will tell you (among other things) that reducing the air temps to the fan and carbs goes a long way toward keeping the engine happy.  More later.

PS- do you have any idea what components are in your 2332?

It's just so cool to see something that can be done right actually done right.  If I had ears worthy of such a system, I might be tempted. Ditto your Speedster, it's a real beauty, and sure is red.  FWIW, I had a pretty serious ding on the front end a while back, turned out to be an insurance job -- road hazard.  The fix was a complete redo of paint etc. from front bumper to door seams.  Excellent job by a guy who knows his shyt.  Decided all that new paint did not deserve another bunch of years of road rash, so went with a premium PPF.  Pretty pricey option, again done by a class shop that knew what they were doing, although they had never seen a '57 Speedster.  I'd highly recommend that for what you have here.  We get road rash.  PPF fixes that.

I just looked it up. I used #2 cable when I relocated my battery up front.

https://a.co/d/0nTrVAh

Had to go all the way back to 2019. Time flies when you’re having fun!

@Teammccalla

Back to your slow starting problem, do you know what the compression ratio is in your engine?  If you don’t know that, then maybe you could put a compression tester on it and let us know what the gauge reads?  (One cylinder should do )

I’m wondering whether the starter is working really hard to turn it over because of high compression, or the starter is being starved for power due to inadequate battery/starter cables or poor cable connections.

I run #0000 welding cable ( often called 4/0 AWG ) for BOTH main positive and ground cables.  Connectors on both ends of the cables are swaged-on for the best connection.  Welding cable is very fine stranded, making it very flexible, but because it is fine stranded it can pass more current, the thing that provides power to your starter.  The bad news is that for a 10’ length you’ll pay $75 - 100 bucks.  But if it cures your hard start problems……..

@Gordon Nichols posted:

@Teammccalla

Back to your slow starting problem, do you know what the compression ratio is in your engine?  If you don’t know that, then maybe you could put a compression tester on it and let us know what the gauge reads?  (One cylinder should do )

I’m wondering whether the starter is working really hard to turn it over because of high compression, or the starter is being starved for power due to inadequate battery/starter cables or poor cable connections.

I run #0000 welding cable ( often called 4/0 AWG ) for BOTH main positive and ground cables.  Connectors on both ends of the cables are swaged-on for the best connection.  Welding cable is very fine stranded, making it very flexible, but because it is fine stranded it can pass more current, the thing that provides power to your starter.  The bad news is that for a 10’ length you’ll pay $75 - 100 bucks.  But if it cures your hard start problems……..

This is a VMC 2332, that originally had Kadron's. I bet it is nothing more than 9-9.5 to 1. I used an autostick starter on a 13 to 1 drag motor. Compression isn't the problem.

Gordon thanks for the heads up on a cable.... I wasn't sure if I had a ground problem with my subie engine, it ended up being the starter slowly dying, but subarus are known for ground issues and many people ground the engine, the tranny etc.

@LI-Rick posted:

This is a VMC 2332, that originally had Kadron's. I bet it is nothing more than 9-9.5 to 1. I used an autistic starter on a 13 to 1 drag motor. Compression isn't the problem.

Now THAT'S FUNNY!

@DannyP posted:

Now THAT'S FUNNY!

Damn auto correct.  That should read Autostick. I’ll make an edit.

Thank you, all.  

The compression is standard VMC.  9.5:1, confirmed with Pat Downs (not 8.2 as VMC lists). The new pistons moved it up a touch, but assume it’s below 10:1.

I think I will try the welding cable.  Seems like a cheap thing to try.  Is there any improvement to ground?

VMC puts their cooler tucked up on the rear seat wall.  It is thermostatic.  Can someone post photos of where it should be closer to the wheel well?

LI-Rick, dittos on auto correct, can be annoying.

Oil cooler placement.  Go to “Resources/Knowledge Base and look for Full Flow oil cooler upgrade.  Part one explains what we’re doing and placement of assemblies, and part 3 gives a little more detail.

https://www.speedsterowners.com/forum/knowledgebase

https://www.speedsterowners.co...ooler-upgrade-part-1

Thanks, @Gordon Nichols

I am going to try that placement!  Is there a best thermostatic cooler?  I may just use my current one, but I thought I’d ask.

For thread followers, here is the pic Gordon is referring to.  Left wheel well:

My cooler is a DeRale 16-pass fan assisted model.  It has an integral thermostat and relay to turn the fan on when the oil temp climbs above 180F

The key things in a cooler are:

(1.) The number of passes of the tubing - 9 pass for light applications, 16 pass for more HD cooling.  You want more cooling capacity.

(2.) A fan assist to move more air through it, especially when stopped.

(3.) AN8 style connections

(4.)  Integral mounting bracket

(5.)  Where it is located for optimum airflow and max cooling

As always, Gordo's install is top drawer all the way.  He's got lots of miles on his I'm thinking with no problems.  Note his rock screen.  This location has me really concerned, out there for who knows what to come up off the road.  But maybe its not really in the line of fire.  I guess not, given that he says no.  But he did put on that screen, so ???  My 2332 got too hot last summer on a 95 deg day of long distance driving , and I'm imagining doing this.  I have a full flow  filter system.  So should be straight forward. right?

I have my oil cooler mounted in a similar position as Gordon's.

One down side is that it prevents me from installing an access opening for the carb.

.

Oh Jeez, is it time for the cooler-in-the-wheel-well thread again? Seems like just yesterday...

Yeah, Gordon is pretty much on top of it, as usual. With 8x10 color glossy photos and a paragraph on the back of each one.

Yes, the stone guard is important. And no, none of the coolers comes with one, so you have to fabricate something on your own.

For years, Vintage and a few others mounted coolers in that closed space between the engine compartment and the rear seat/shelf because it's the most convenient spot for a builder. It's a wide, flat panel close to the engine (short oil line runs) and you can route the lines there without interfering with the exhaust or valve covers. (It's also protected from road debris, so you don't have to fabricate a stone guard.)

But, it's not the best place in terms of efficiently dissipating heat. And the main point of having an oil cooler is to, well, dissipate heat. So, VW folklore has always said to mount them in the wheel well.

But now, Greg at VMC is putting his in that compartment again, flying in the face of folklore. I'm guessing he gets away with this because he's standardized on a Pat Downs build that's in a mild state of tune and with very cool-running heads. (And maybe some other cooling tricks he's keeping close to the vest.)

If your engine is in a higher state of tune and you're already close to having overheating issues on hot days, I'd definitely put the cooler in the wheel well. But, as noted, routing the oil lines around the exhaust headers will be a challenge. Not impossible, but a challenge.

My wheel well mounted (Setrab) cooler has been doing the job without a hitch for about 10 years, now. I'm in California's central valley where most summer days are close to 100, and the fan-assisted cooler isn't an option, it's a necessity. You can watch the oil temp drop back to the center of the gauge when the fan comes on.

The car came from Vintage (in 2013) with a lesser cooler mounted in that space just behind the seat/shelf and the engine would routinely overheat with it mounted there.

This is, of course, free, unsolicited advice, so you'll have to draw your own conclusions about its merits and relative worth.

.

A lot of good advice, @Teammccalla (sorry, I forget your first name?), from Gordon, Mitch, Kelly and Michael.  The problem with using the space in front of the engine compartment and above the transaxle for a cooler is there's no air movement- this is also why a hole in the firewall in front of the fan intake doesn't really help.  At highway speeds there is a solid bank of air flowing horizontally underneath the pan that goes right by the above the trans airspace (also why our cars run hotter at such speeds if not equipped with sled tins and either heater boxes or the industrial side tins).  Earlier I mentioned engine compartment temps was important- both Beetle and Speedster engine compartments (again, at higher speeds) will suffer negative air pressure with bigger engines, starving both the fan and carburetors, with what they are getting being pre-warmed by heat radiating off the engine components.  Airflow THROUGH the engine compartment creates positive pressure, will feed enough air to the cooling and intake systems properly, takes away radiated heat which reduces air temps so the systems can work as intended and the engine runs within proper parameters more of the time.

After a long highway drive, stop, quickly run around to the engine compartment and put a hand on a cylinder cover- if you can't keep it there more than a couple of seconds, the engine is running too hot.  Or, put a drop or water on the engine case.  If it sizzles...

Kirk, when he ran Vintage Speedsters, equipped a lot of his cars with a big hole in the firewall in front of the fan shroud, but because of that layer of air underneath the car at speed, really didn't do anything.  But guys on the Samba have proven that if you re-direct air up into that area it goes a long way to keeping even a bigger, more powerful engine cooler.

This guy claimed a 10° reduction in oil temps with this air deflector in his bus.   Another fellow in Utah (Salt Lake City?) with a big engine in his street bug (ran mid to high 11's in the quarter mile- may have been turbo'd?) found that removing the front breastplate off the engine made a world of difference in the engine's ability to keep itself operating within normal parameters.

I think the deflector could be bigger...

@ALB  YES.  That was always my thought!  Why move it when you can do something to flow air to the space where it is mounted?!  I found your comments about negative pressure in the engine compartment interesting too.  Is there anyone out there who is making ducting to help with cooling and air pressure?

@Butcher Boy I know you are handy with metal fabrication (I still want one of your metal left foot carpet covers!). I’m wondering if you have put any thought into air flow.  Since yours is a Subbie maybe not.

@Sacto Mitch Your post was on the money.  You make a lot of sense.  Higher state of tune, etc.  It’s hot in Los Gatos, and there’s a lot of traffic on 17.  I’m always worried about frying it.

Randy

@Teammccalla- Thanks, Randy!  More to follow...

Randy.......back in about 2014 I tested the negative pressure in the engine compartment with a water manometer. if I remember correctly, it was negative by about 2" @ 65mph. This was with a totally sealed engine compartment. I found that the restriction was caused by the "Rain Shield' under the intake grill.  I measured and calculated the square inches of the intake grill (less the area taken up by the actual grill bars) and then measured and calculated the square inches of the openings where the air actually enters the engine compartment on the right and left sides. This is where the restriction is.  If I remember correctly, it's about 1/2 to 1/3 of the area of the grill.

I found that not closing the engine lid eliminated the negative pressure was the easiest way solve this. One of our readers on here drives his car like this and is happy. Others have cut about a 4" hole in the rain shield just below the grill and installed mesh to keep the "big rocks" out. This solves the problem but eliminates the purpose of the rain shield such the water now runs down onto the distributor.  Out here, where "it never rains in California" we are OK with that.   I hope this helps ............Bruce

@aircooled Really appreciate that reply.  I am vain, and it does rain here, even if it only comes from a garden hose.  No cutting holes in the hood.

My car is not totally sealed inside the engine compartment because it is a VMC.  It is open around the edges of the front.  I am thinking some kind of scoop from underneath into the compartment?  There HAS to be a prefab something out there for brakes, or radiators or something….  Anyone?

This might be the only place where your reference is recognized.  HUGE song, and not entirely forgotten.  However, only here would we all know your joke.

_____

I found the following on the net.  Aircooled is cited, but it may be cobbled together from other sources, such as CIP.  I am not sure how to translate this to our Speedster applications.  Can someone help?  Would this mean we should seal the compartment?  Add deflectors?  Some other airflow device?

http://www.vw-resource.com/overheating.html

... he just wants to ride his motorsickle.

I like the low-down scoop/deflector idea to pump up the air pressure in the back wall area.  Might be worth the added drag.  I wonder if it would whistle? That back cavity space sems like the exact right place for an oil cooler, but not if there is no air flow.  Then again, isn't that what the fan on the cooler is for -- to move air?? Of note: my car did come with a hole cut in the "fire-wall" opposite the fan inlet.  And I still got overheated.  If the slip stream under the pan just rushes by that open space, then good ol' Bernoulli is going to have something to say about that.  The pressure will go negative relative to ambient as the air whistles on by.  Propping up the back "hood" a few inches is really just too simple. I've not tried that, and figure I can McGiver a prop that would work.  I'll try that.  I have also imagined, but not moved on, setting up a water manometer to get some real data on the air pressures in there above 60 mph.  Seems like that science has already been done, and the votes are in.

.

I'll just add this.

Over the years that I've been following here (and it's more than a dozen, now), there have been countless long discussions about keeping these engines cool in hot weather.

There's been endless speculation and hand-waving theory about what might work. But, as very few of us are trained engineers in the appropriate sciences and even fewer have access to the kind of diagnostic tools and techniques that the pros use when they design this stuff, there has been a lot more heat than light generated.

The only technique that I recall receiving consistent endorsement from folks who have tried it is opening the engine lid a few inches when it gets really hot out. It's not too hard to make up a small prop rod at the hood latch that folds out of the way when not needed. VW hot rodders have been doing this for years. A lot of dune buggies just ditch the engine lid altogether.

The basic, inescapable problem is that the engine compartment in the Speedster was designed for a 70 hp engine that generated 70 hp worth of heat. Later, when Porsche started using 90 hp engines, their engineers recognized the problem and doubled up on the grills in the lid. This wasn't a styling thing. Like most such changes, the engineers, not the marketing department, had the final say.

Even the Fuhrman racing engine made only about 130 hp, but for that they added a what? Right — a dedicated oil cooler.

I have seen endless attempts tried by folks on this forum at forcing more air into, out of, under, around, and through the Speedster engine compartment. And no one I can recall ever claimed to have significantly improved things with his shade tree engineering.

I tried something like this myself. When we moved the VS oil cooler out of that compartment in front of the firewall and into the wheel well, I was left with the old VS 8-inch vent hole in the firewall and some wiring leading to the old cooler fan. It was no big deal to add an electric fan to force air from there into the engine compartment. How could that not help things?

Well, I was never invited to write up my findings in the Sacramento Journal of Science, but my conclusions would have been that it helped not a whit. I think the main thing is that real engineers designed that squirrel cage fan and its housing that we all have spinning on our engines and they used real science and real slide rules in the process. And nothing I can do with parts from Home Depot and the Auto Zone are going to make any significant difference.

You may have better luck than me, but the laws of probability (real science, again) are not on your side.

.

I don't have the engine heat problem on my speedster. But if I did I would keep it simple make a rear engine prop to allow the deck lid to be open on hot days. I also would install an oil temp gauge or the simple candy thermometer in the dip stick hole to check oil temp on hot days so you have some idea of how the engine is doing. Other then that, just drive it and enjoy the drive..

^^THAT^^
And if you’re going to the trouble of monitoring your engine temperature on hot days under different conditions with a dipstick thermometer (which I highly recommend), make a mental note of where the needle is on your dash gauge at “normal” runs and then at the hottest temp you see so you’ll have a better idea from then on.  It’s a simple thing to do.  

You could even place a small piece of tape or something on the gauge that tells you;  “Don’t let it run higher than THIS!”

I think I’ll try a Derale 16 in the original area and some scoops.  Maybe I’ll ask Greg about scoops.

Oh, I ran across my notes from a conversation with Pat Downs. He said our 2332 VMC engines are 9.5:1, not 8.2:1 as the VMC literature indicates.  I will correct that above.

I think I tested that void area in front of the firewall and it indicated a negative pressure at 65mph as well.  I plugged up the VS firewall hole on my Speedster when I made sure that the engine compartment was totally sealed.

I then had 4 oil temp sending units plugged into my engine so I could monitor the oil temps simultaneously.  I used a rotary switch to quickly cycle thru all the temps.  (so I didn't have to buy 4 gauges)  One on the inlet and outlet of the stock oil cooler, one on the outlet of the aux. oil cooler out in the fender well and the last one directly in the oil sump near the pick-up tube..

The reason I did all this was because I could tell that my engine was running hot and I wanted to know why and where.  I used a very accurate thermocouple probe down the dipstick tube to verify this.

After reading about all the methods tried by many of you members here, I decided that the best method was to seal off the engine compartment like the VW/Porsche engineers intended. They obviously went thru great pains to do this so that is what I did.  My logic dictated that the modified engines we now use in these cars will and do generate more heat, Hence, an external oil cooler in the left-rear fender well in addition the stock cooler.  By doing what I did, I solved my engine cooling problem. About this time I was curious if the grill was a restriction because All the air for the engine now had to come thru the grill. Alas, I measured a negative pressure !  For me, I had already eliminated my cooling issue but perhaps I could get my temps down even further by eliminating this air flow restriction.  I mentioned different methods in my previous post but what I did was remove the most material I could on the rain guard under my hood.  I found these photos of what I was looking at.  I borrowed this hood and rain guard from Greg.  Please note that most of the actual rain guard that covers the distributor had been removed.  This was OK because I was more interested in the restrictions on either side and that is what I measured.

The end result is that I removed a lot of the rain guard on the right and left sides , leaving the center part over the distributor.  This eliminated the negative pressure and slightly lowered the oil temp.  Only around 3 f in the sump.

An interesting note and surprising to me was that the stock oil cooler only had a difference of 4 degrees F. between the inlet and its outlet. It's a very high volume flow but I didn't expect that kind of number and still don';t really know why or how it cools the engine at all. Even on a stock engine.  ............BRUCE

@aircooled- I was hoping you'd run a hose up into the 'void' to see if that would pressurize the area (and feed the engine compartment) but by then you were done.      Do you remember what weight oil you were running in that engine?

Al.........I believe I was using Brad Penn 10w/30.   I think I did put a hose in there and I think I posted it on here but don't know how to find it..........Bruce

These?

https://www.speedsterowners.co...anometer-test?page=1

https://www.speedsterowners.co...ults#google_vignette

Thermodynamics  ... I have a degree in that, and spent most of my career cyphering on those principles, albeit with emphasis on what happens at Mach-alot.  All this back-yard engineering and scientific experimentation at subsonic speeds is completely on point.  Very good work.  As to negative pressure in the engine compartment, that really does sound about right given the design of the fan mounted in the shroud, sucking air in to the tins at a high rate.  That said, if one could increase the ambient pressure inside the engine bay, and decrease the resistance to air flowing from outside to inside, that fan will push more air.  I will invest in an engine lid prop -- that can't be too hard.  and will use it if/when required, and see if it helps.

Alb.......Wow !  Did I do all that ?  hmmmm !  I was wrong in my recollection of the area in front of the firewall.  It appears that there was a positive pressure in there, not negative.  Thanks for posting those.......Bruce

@El Frazoo posted:

Thermodynamics  ... I have a degree in that, and spent most of my career cyphering on those principles, albeit with emphasis on what happens at Mach-alot.

Great, you’re just the person to run this by, I was going to post it yesterday and got distracted:

When I was “doing my own research” wrt my Spyder getting really hot driving at consistent high revs (freeway) or pulling a long grade, and finding out about the Cooled Thing repro shroud I read something that seemed a bit fantastical. I can’t remember if it was in the Concept1 sales lit, Jake Raby’s endless cooling thread on the Samba, or just some random forum post, but someone postulated that you can actually have TOO MUCH airflow over a cooler, that as the temperature of the vanes goes down past a certain point, so does the heat transfer. Seemed like mumbo jumbo to me. Is there any validity to that?

dlearl476......Very good question !...........Bruce

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@Teammccalla

Randy, sorry I didn't realize you have a Pat Downs 2332 in a recent VMC build.

Before attempting anything on your own, why not just talk to Pat directly about this issue?

No one knows more about keeping these engines running cool than he does. He lives in the central valley and has been building VW engines here for over 20 years. I'd guess he'd be willing to spend a few minutes on the phone with you as he built your engine and has a pretty good reputation for wanting to keep customers happy.

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@aircooled posted:

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An interesting note and surprising to me was that the stock oil cooler only had a difference of 4 degrees F. between the inlet and its outlet. It's a very high volume flow but I didn't expect that kind of number and still don';t really know why or how it cools the engine at all. Even on a stock engine.  ............BRUCE

Bruce just to be sure: was your stock oil cooler's "exhaust" ducted to a spot under the tins? Asking because, on my Spyder build with the DTM shroud, the fan put a good amount of air through the stock cooler.

Ed.....Yes the complete ducting to make the air on the outlet side of the oil cooler go down (an if I recall) and out in front of the tin that blocks off around the bell housing.  The cooler was the large HD unit that bolts to the adaptor which is fastened to the crankcase.  Both of the temp. sending units were installed in that adaptor. One in the inlet and one in the outlet. I welded bungs into that adaptor such that the temp senders,  when installed, did not restrict the oil flow.  There is a tremendous amount of air flow thru that cooler.  You can feel how much if you happen to be around it when an engine is on a dyno !..........Bruce

@dlearl476, as to the physics, generally speaking, film cooling over a flat surface always increases with bulk air speed.  The engineering issue is usually centered around is the flow laminar or turbulent.  Laminar flow occurs under very restrictive conditions and is characterized by lower fluid speeds and hence lower heat transfer rate than if the flow is turbulent. I had some situations with hardware where we purposely introduced tiny obstructions in the flow channel to purposely trip the flow from laminar to turbulent. I can't see how the air flow induced by the engine fan is anything but turbulent, especially at higher engine speeds.  So likely we would see ever more heat transferred the higher the velocity through the cooler's fins. Turbulent flow generally requires higher pressure differences in order to achieve a certain bulk flow through a passage and the relationship is non-linear .  All of that said the design could reach a point where the turbulence is so great that ever more action by the fan (higher engine speeds and also higher heat generated) might not result in much increase in bulk air flow.  At such a point the actual air flow through the cooler fins would not go up in direct  proportion to the fan speed and the increase in engine heat output would not be accommodated by the cooler, basically being choked out for flow rate.   At high revs, the engine fan might be beating the air to death, but the cooler fins are just not letting enough air through to match the increase in heat load.  And a centrifugal fan like we have on these engines does have a performance curve showing output vs rpm at one atmosphere ambient,  and I'm betting that CFM falls off at higher rpms, and does not just keep going up the faster it spins.  Just a theory.

I could not find a performance curve for centrifugal fans when spun too fast.  Did find some data that shows the operating curve for a fan (CFM vs RPM) is not quite linear.  So I'm going to hold to my claim that if a given fan is spun too fast, the actual output in CFM could go down, or at least level off.  I'm going to say that these fans have a CFM vs RPM curve that peaks at some speed beyond its proper design point.  I think at some point the faster the fan spins the flow over the fan impellers will separate off the trailing edge and form a recirculation eddy off that trailing edge, and this will spoil the back pressure and CFM will decrease with increasing RPM.  That makes sense to me.

FWIW, boat propellers can spin so fast that the pressure along the blade falls below the vapor pressure of the water and water vapor (or dissolved gas) bubbles form -- called cavitation.  When these bubbles collapse, they can do so with explosive force, and in some cases can erode the propeller.  Even absent actual damage, cavitation greatly reduces the efficiency of the propeller and the thrust it delivers will go way down.