Skip to main content

Hello to all, last year I bought a set of the CB Performance Turbo Hats to put on my 2110 CMC WB and just now am finally getting around to getting it done. Question: can the Aluminum Pressure Covers be painted? and if so what type of paint/prep should be used? Please advise.

Turbo-Hat

Attachments

Images (1)
  • Turbo-Hat
Original Post

Replies sorted oldest to newest

Yes, you can paint them. The secret is no secret, you need proper prep.

Step One: After a light sanding or bead blasting clean the hell out of them. Soak them inside and out in acetone, denatured alcohol, or something like brake clean several times over. Aluminum is porous and any oils that get on it will get into those pores. Even oil from your hands. (You're using gloves with this s**t anyway, right?)

StepTwo: Use a self etching primer made for aluminum. Rustoleum has good one specifically for aluminum and that sets you up to use any other Rustoleum paint for the color and clearcoat if you're going for glossy.

That's it. Poison clean, self etching primer, keep things in the right temperature range, wear gloves, don't breath it in. You get the idea. I always thought these would look good in a wrinkle black finish.

@Stan Galat : Yes, I am running a turbo on a 2180cc motor with 68cc Panchito 44 heads, 92mm thick wall cylinders, 8.2 : 1 compression, CB Performance 2242 camshaft, Megasquirt EFI running Tuner Studio software, external oil cooler, thin-line oil sump, full flow 31mm oil pump, electric fuel pump, crank fire ignition, hideaway turbo kit with T03/T04 turbocharger exiting through a modified tri-mil exhaust.  A few other engine modifications have been done...but the best parts are listed. 

@Stan Galat : Yes, I am running a turbo on a 2180cc motor with 68cc Panchito 44 heads, 92mm thick wall cylinders, 8.2 : 1 compression, CB Performance 2242 camshaft, Megasquirt EFI running Tuner Studio software, external oil cooler, thin-line oil sump, full flow 31mm oil pump, electric fuel pump, crank fire ignition, hideaway turbo kit with T03/T04 turbocharger exiting through a modified tri-mil exhaust.  A few other engine modifications have been done...but the best parts are listed. 

Dang. Did you dyno the motor?

@Stan Galat : I haven’t yet made it to a dyno.  The engine pre-turbo was believed to be in the 135 - 150hp range running Webber 44’s.  Estimates put me in the low 200’s with the boost.

The Webber 44’s were just too fickle with the turbo so I made the jump to  the EFI and crank fire additions which delayed my dyno plans.  I’m hoping to get some actual numbers sooner than later though.

Hi Stan - you are correct! DID NOT convert my engine to a Turbo. Putting CB "turbo hats" with a cone-type filter on the inlet to prevent "Hydro-Lock".  and most importantly - the set-up dramatically reduces the risk of a fire in the event of a backfire.  We shall see........

Yep. I've had them for several years for that reason. A quick search will bring up a thread on the benefits.

Yes, you can paint them. The secret is no secret, you need proper prep.

Step One: After a light sanding or bead blasting clean the hell out of them. Soak them inside and out in acetone, denatured alcohol, or something like brake clean several times over. Aluminum is porous and any oils that get on it will get into those pores. Even oil from your hands. (You're using gloves with this s**t anyway, right?)

StepTwo: Use a self etching primer made for aluminum. Rustoleum has good one specifically for aluminum and that sets you up to use any other Rustoleum paint for the color and clearcoat if you're going for glossy.

That's it. Poison clean, self etching primer, keep things in the right temperature range, wear gloves, don't breath it in. You get the idea. I always thought these would look good in a wrinkle black finish.

Thanks, Michael, for your feedback!

I powder coated mine.  I got pretty close to the body color.  Another option is ceramic coating or a nice wrinkle black as JMM suggested.

I always thought they’d look pretty cool with dual air filters.  I went a different direction!

B437ED1C-41EC-487A-A839-4F19699F86DE

Yeah, I'm going the dual-filter route, trying to get mine to match the car also, Like the color of your car. May I ask - where is your air filters......

Yeah, I'm going the dual-filter route, trying to get mine to match the car also, Like the color of your car. May I ask - where is your air filters......

I have a single K&N air filter attached to the inlet side of the turbo.  If you look slightly down and to the left of the pulley you’ll see a chrome ring.  That is the top of a K&N RR-3003 reverse conical filter.  It pulls air into the turbo that then gets pushed through the red tubes to the hats on the EFI throttle bodies.  I inserted a connection to run a vent line to the oil filler tube…that’s the grey line you see coming out the middle of the filter.

This particular filter has effectively twice the surface area as it draws on both the exterior and interior of the element.

Hi Stan - you are correct! DID NOT convert my engine to a Turbo. Putting CB "turbo hats" with a cone-type filter on the inlet to prevent "Hydro-Lock".  and most importantly - the set-up dramatically reduces the risk of a fire in the event of a backfire.  We shall see........

The other benefit is slightly reduced intake noise. The noise is still there, just directed away from your ears.

.

As long as you've got hats breathing through tubes, has anyone played with the idea of drawing air from somewhere cooler, outside the engine compartment, like maybe the wheel wells?

Once saw a 912 with intakes routed through holes in the engine bay side panels.

And there are the Emory coupes that do something related, although the carb intakes probably aren't ducted directly to the louvers:



EmoryOutlaw2

.

Attachments

Images (1)
  • EmoryOutlaw2

I have a single K&N air filter attached to the inlet side of the turbo.  If you look slightly down and to the left of the pulley you’ll see a chrome ring.  That is the top of a K&N RR-3003 reverse conical filter.  It pulls air into the turbo that then gets pushed through the red tubes to the hats on the EFI throttle bodies.  I inserted a connection to run a vent line to the oil filler tube…that’s the grey line you see coming out the middle of the filter.

This particular filter has effectively twice the surface area as it draws on both the exterior and interior of the element.

Great....I thought it was something like that,,,,,

More holes into the engine compartment is a very good thing, but regardless of the folklore and common knowledge, there will be no air blowing out any of them unless there is something horribly wrong.

There's a giant fan moving about as much air as the furnace blower in your house, sucking air out of the engine compartment, blowing it across the heads and cylinders, and out the bottom. The reason these cars run hot is that all the holes into the engine compartment are in low pressure zones - but they are not so low that they are enough to overcome the suction of the fan. Air moves into the engine compartment. Getting more air back there, by whatever means possible is the holy grail of cooling.

... and Mitch - yes, I would bet every last one of us have thought about using those inlets as ram air for the carbs. Building airboxes would be a trick.

I have a single K&N air filter attached to the inlet side of the turbo.  If you look slightly down and to the left of the pulley you’ll see a chrome ring.  That is the top of a K&N RR-3003 reverse conical filter.  It pulls air into the turbo that then gets pushed through the red tubes to the hats on the EFI throttle bodies.  I inserted a connection to run a vent line to the oil filler tube…that’s the grey line you see coming out the middle of the filter.

This particular filter has effectively twice the surface area as it draws on both the exterior and interior of the element.



Nope.

So - out of curiosity (and because I'm an engine math geek), I went down a wormhole tonight. My question was regarding how much air a typical Speedster engine ingests running down the road - both air used for cooling and air used in combustion.

I'm not sure if any of this is worth anything, but here goes:

On the combustion side, a couple of minutes of Googling turned up two different websites on the first page - one that does a good job of explaining things, and one with a calculator. To answer my combustion-air question, I needed to establish what this engine was. Since this is a Speedster, I decided to figure out what a 2110 making 150 hp at 6000 RPM needed. There are several different ways to come at this, but the math doesn't really change much.

Some of how I'm explaining this is lifted from the first article, paraphrased for brevity and clarity.

A 4-cycle engine operating at 100% volumetric efficiency ingests its swept area (displacement) every two revolutions - so a 2110 cc engine running at 6000 RPM sucks 2110 cc of air 3000 time a minute. However, this is hypothetical (and not particularly useful), since it assumes 100% volumetric efficiency. The mass of ingested air is directly proportional to air density and most important to what I'm trying to figure out - volumetric efficiency.

An engine's volumetric efficiency curve pretty closely mirrors its torque curve. For modern naturally-aspirated, two-valve-per-cylinder, pushrod-engines - a volumetric efficiency over 95% is considered excellent. 100% is achievable, but quite difficult. Only the very best modern NA engines can reach 110% . The practical limit for normally-aspirated engines (DOHC layout with four valves per cylinder) is about 115%, which can only be achieved under the most highly-developed conditions, with crazy intake and exhaust tuning (Porsche "Vario-Ram" and the like).

Generally, the RPM at peak volumetric efficiency coincides with the RPM at the torque peak. And generally, automotive engines rarely exceed 90% volumetric efficiency.

All that means that 90% (.9) of displacement x .5 RPM is the absolute outer limit of airflow through the engine. I'm speculating that a more conservative general volumetric efficiency for our engines would be 80% (.8). A dyno chart will often have those numbers as well.

Anyhow, there was a calculator on one of the sites. With the variables I had (2110, 6000 RPM, .8 VE) plugged in, it spit out 179 cubic feet/ minute (or 5064 L/min). It wouldn't be less than that, I shouldn't think.

That's less air than I suspected it would be, but it's still a fair amount.

The air that a T1 doghouse fan moves is another problem. The fan wheel is a backward curve fan, and it's CFM rating in free air would be pretty easy to establish, but that's not how fans work. Fans run against resistance - the fan is blowing directly onto a bunch of fins and solid cylinder and head, in addition to being forced through the cooling passages. If you "dead-head" a fan, it moves no air at all. As nearly as I can find (from a thread on the ShopTalkForums) the accepted flow of a doghouse fan on an actual T1 engine is about 1440 CFM. Maybe more digging would turn up better information, but that's what I got with a pretty brief search.

So, 1440 CFM for the fan and 179 CFM for the engine itself is about 1600 CFM. That's enough air for all of the ductwork in a house with a 4-ton A/C system - that's a bigger residential unit for a pretty good-sized house. Think of all the registers in your house and how much air they blow  - it's a lot of air.

Here's where it gets a bit fuzzier. Typically, we size ductwork for a .1 static pressure drop at 1000 fpm of velocity. This is the probable weak link in my speculations - I have no idea what would be realistic numbers to plug into an automotive application. But running with that and according to my duct calculator, at those conditions, you'd need an open cross-sectional area of about 16" x 16", and that assumes atmospheric pressure at the inlet. We know that the area the car is getting air from is a negative pressure zone.

So, we're making an educated guess at the minimum cross sectional area ideally required, but it's probably not going to be less than 256 sq inches. That's nowhere near exact science (because I'm not an actual automotive engineer), but unless I'm really cloudy tonight - it's at least in the ballpark. Regardless, decreasing the inlet area increases the static pressure, which decreases the fan performance.

I'm guessing the only T1 engines that really get enough air are Baja Bugs, sand-rails, and dragsters without deck-lids, which explains why desert racers are able to run for hours in the desert at WOT, and I struggle on a desert highway unless I back it off or pop the deck-lid or both.

If the fan and the intake system are in competition for air, I'm not sure which would win out (it would be the one with the stronger vacuum, which I would suppose to be the intake), but I would suppose it wouldn't be optimal for either. I'm guessing most of us are really starved for air, which is why popping the deck-lid an inch or two on a really hot day lowers temps at least 10 deg. That, I can say for sure.

In short - I'm not sure how else to say it. The air is not ever going to blow out of a hole in the bodywork on the inlet side of the fan and induction system. Getting the engine more air is probably one of the most overlooked modifications (at least by me) I could be making for my engine.

At a minimum, I really should cut finally out the rain tray. Also - I really wish the pipes on the turbo-hats were 3" instead of 2".

9BCEF604-6097-448B-B65F-567DC0CD67FD

Attachments

Images (1)
  • 9BCEF604-6097-448B-B65F-567DC0CD67FD
Last edited by Stan Galat

I'm not sure I understand the question, but yeah - the reason we seal between the hot side and the cold side is to keep the fan (and engine) from sucking the hot air it just ran over the heads and cylinders. In other words, removing all of the surround tin would absolutely provide the engine with more air - but it'd be hot air we just used for cooling already. It would set up a loop of reusing air again and again and the air would just keep getting hotter.

Also, colder air is more dense (hence, the sentence about mass air flow) and does more with the same absolute CFM. That's why EFI systems use "mass air" sensors. What they do is absolutely brilliant. Guys who design this stuff have forgotten more by coffee break on Monday than I'll learn in a lifetime.

Last edited by Stan Galat

.

Interesting stuff, Stan, but I was wondering not about drawing more air, but drawing cooler air.

Of course, there are a ton of after-market induction mods for mass-market cars to access cooler intake air, but most car makers also go to a lot of trouble routing intakes to the forward part of a (front-engined) engine compartment (and generally to in front of the radiator).

Both of my modern cars do this (MINI and Subaru), and even my '68 2002 did. (That car even had a small, plastic manifold that could be switched to 'winter' or 'summer' modes to preheat intake air in winter across the exhaust manifold or draw air from in front of the radiator in the summer).

Budgets being what they are in the car biz, they wouldn't bother doing it if it didn't make a difference.

I'm wondering if just drawing air from the wheel wells (instead of the much warmer engine compartment) on our cars would make any noticeable difference.

My car certainly seems to have more jump in 50 degree ambient air than when it's 80.

Last edited by Sacto Mitch

I've wondered that as well, Mitch - and if the "all-for-looks" side intakes on Al's (and Emory's) outlaw wouldn't provide a lot of real-world functionality as air-boxes. I was serious above .

Cooler intake air would be the holy grail. I've even thought about (and began to explore) the feasibility of a methanol injection system in my turbo-hats.

But more total air into the engine bay is a great first step to start. It's also why I did all the stuff I did with regards to cooling (beehive springs, DTM with sled tins, tc.) on the 2234 I've yet to install. Mostly, I started down the rabbit-trail to see if I could definitively put to bed the notion that we'd EVER blow (rather than draw) air from the intake side of the engine compartment. There have been people proposing that for 10+ years here.

I'm dead serious about cutting out the rain tray.

Last edited by Stan Galat

The Outlaw duct work is functional. I will post pics when I get the body back from paint. A horizontal aluminum scoop mounted 1" or so below the trans would be a plus for cooler ambient air temps into the engine bay and adding additional cut out's in the underside of the deck lid and or removal of the deck lid rain tray plus an opening cut out behind the license plate as IM did would all contribute to hot air egress. I also did half a dozen deck lid 12v actuator installs that raised the lid a couple inches did wonders too.

Last edited by Alan Merklin

Yeah, Al - I know the intakes dump air into the engine compartment. I suppose the idea though is to use that air exclusively for the intake, rather than as "common" air for both intake and cooling.

Generally though - my contention is that both (intake and cooling air) are generally starved, and that just getting more fresh air to both would be a huge benefit to us. Holes in the bodywork are not going to be for hot air egress, though - all the hot air is going out the bottom or out the tailpipe (for all the reasons I listed above) - holes on the intake side are for supply air. It's no secret that popping the deck-lid an inch or two makes a pretty significant difference when losing control on temperature, and absolutely everybody knows how much better an engine runs on 50 deg morning rather than a 95 deg afternoon.

When it comes to cool air, both to the intake and the cooling fan - more really is a lot more.

Last edited by Stan Galat
@Stan Galat posted:

So - out of curiosity (and because I'm an engine math geek), I went down a wormhole tonight.





I love it when that happens!

I'm kinda amazed that anyone would assume extra holes or a popped deck-lid would let any air out. Both the fan and the engine are working overtime to remove air from the engine compartment, and the result would always be a negative air pressure there. I can't see the negative pressure created behind the car ever exceeding the negative pressure in the engine compartment. If it did the engine would stop running!

I remember seeing an article about a 356 G-production racer many many years ago. He had to follow SCCA rules about ducting, scoops and stock appearances and found a loophole. He used the right side headlight bucket and ran a straght tube all the way through the passenger compartment into the engine compartment to supply cold fresh air. I'm not sure how effective it was (duct size, length, friction) but it was clever!

I'm kinda amazed that anyone would assume extra holes or a popped deck-lid would let any air out. Both the fan and the engine are working overtime to remove air from the engine compartment, and the result would always be a negative air pressure there. I can't see the negative pressure created behind the car ever exceeding the negative pressure in the engine compartment. If it did the engine would stop running!

It’s a much more common misconception than you’re aware of Michael, even though it defies all logic.

Last edited by Stan Galat

.

Stan, i think we're on the same page. I posted that as an example of the many 'cold air intake' devices that have been around for years (and apparently selling very well, I guess).

The science and the folklore seem to agree that colder intake air is a good thing. It's just a question of how to get there.

There's been much debate in the Miata community over whether things like the pictured device actually get the job done. Here's a guy who found they don't, after running some tests and posting a video.

Which has me wondering about the turbo hats as a way to get there for our cars. Here's an off-the-shelf bolt on that easily gets half the job done. It isolates all intake air from the engine compartment and terminates in a fitting that connects easily to other ducting.

It would seem an easy thing to hook up some hose, drill some holes into the wheel well, and fabricate something to filter out dust, leaves, and tree limbs. But I've never seen anyone do that and I'm wondering why not.

Emory does something similar with his louvered panels (and he got the idea from some factory racing 356's back in the day. But I think those just bring air into the engine compartment and aren't plumbed directly to the carbs) :

356SideLouvers02

What am I missing here?

.

Attachments

Images (1)
  • 356SideLouvers02
Last edited by Sacto Mitch
Post Content
×
×
×
×
Link copied to your clipboard.
×
×