SuzukiSavage.com /cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Epoxy Test for Port Mods /cgi-bin/YaBB.pl?num=1557210973 Message started by DragBikeMike on 05/06/19 at 23:36:12

Title: Epoxy Test for Port Mods Post by DragBikeMike on 05/06/19 at 23:36:12 To prepare for port modifications, I tested two epoxies and one filler paste to see if they are appropriate for modifying the intake port and exhaust port.   Based on readings that I took on the exterior of the head, and information Dave has provided from his installed cylinder head temperature meter, the anticipated intake port temperature should be around 300°F to 350°F.  The interior of the port is continuously cooled by the flow of intake air, along with the fuel droplets that are vaporizing as they pass through the port.  I don’t know exactly what the highest anticipated port surface temperature is, but I think using an assumed 350°F is a conservative approach.   The exhaust port is another story.  It’s hotter than the devil’s den in there (well over 1000°F).  No epoxy that I could find will withstand the extremely hot exhaust gas.  I think it will require some sort of ceramic paste.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/06/19 at 23:38:59 I started with products that are readily available at the local auto parts stores.  JB Weld is my go-to epoxy, so I stuck with their brand.   For the intake port, I looked at original JB Weld epoxy paste and an epoxy putty called JB Weld High Heat.  Original JB Weld is a two-part paste while the High Heat product is a two-part putty.  The original JB Weld is rated at 500°F continuous while the High Heat product is rated at 450°F continuous. Here’s a shot of the original JB Weld.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/06/19 at 23:40:05 Here’s a shot of the High Heat.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/06/19 at 23:41:05 For the exhaust port, I looked at a JB Weld product called “Extreme Heat”.  It’s a one-part paste.  It’s water base and contains steel fines, silicic acid, and sodium salt.  It’s rated at 2400°F continuous.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/06/19 at 23:42:48 I tested the epoxy products for temperature resistance, fuel resistance, adhesion, and tensile strength.  I will be using an epoxy in the intake port where the temperature should not exceed 350°F. I tested the Extreme Heat product for adhesion, temperature resistance, and tensile strength.  If it holds up to the tests, it will be used in the exhaust port. Each product was applied on a section of aluminum angle in accordance with the manufacturer’s instructions.  Prior to application of a product, the test surface was thoroughly degreased with Brake-clean, and an anchor profile was ground into the test surface.   This is what the test surface looked like prior to application of a product.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/06/19 at 23:44:58 I allowed the products to cure for at least 48 hours after the initial application.  Then I blended the products into the adjacent aluminum to get a feel for the bond line.  I used abrasive porting rolls to do the blending. Here is the original JB Weld after blending.  Pretty good edges but note the small holes.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/06/19 at 23:46:17 Here is the High Heat after blending.  Pretty good edges, no holes.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/06/19 at 23:47:28 Here’s a look at the Extreme Heat after blending.  Lots of holes but the edges look OK.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/06/19 at 23:49:17 I washed the specimens in the sink and right off I could tell the extreme heat product seemed to be dissolving.  Not a good sign.  The two epoxies weren’t affected by the water. I sawed each specimen in half using a chop-saw with a carbide blade.  I mounted the specimen in the saw such that blade rotation would tend to pull the epoxy/filler-paste off the aluminum angle.  I believe the shearing action from the blade along with the heat generated by the dry cut subjected the bond to quite a bit of stress.  After the saw cut, I examined the bond line. Here’s a look at the bond line on the original JB Weld.  It looks pretty good except for one small area where I could detect what appeared to be slight separation between the epoxy and substrate.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/06/19 at 23:50:11 This shows how the High Heat held up to the saw.  It showed a very tight joint with no evidence of separation.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/06/19 at 23:51:27 The Extreme Heat handled the saw just fine, but you can see this stuff is very porous.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/06/19 at 23:56:14 Because I was concerned about water solubility with the Extreme Heat product, I placed half of the specimen in a jar of water.  Within 15 minutes the entire layer of cured paste was gone.  It totally dissolved. While there is little concern over water in the exhaust port, I am a BIG fan of a nice hot, soapy, water bath prior to assembly.  I want ALL the grit out before I put it together.  Port mods require grinding, and this cured product is like rock.  Clean-up after the port work will be mandatory and a filler that dissolves in water just won’t cut it.  Things were looking bleak for the Extreme Heat filler. Just for info, I submerged the two epoxy specimens in water and left them over-night.  It didn’t affect the epoxy.  Time to lite-off the BBQ. I baked all the specimens in my BBQ at 450°F for four hours, then I removed the two epoxy specimens and left the Extreme Heat specimen in the cooker.  I raised the temp to maximum and monitored the surface temperature of the specimen every hour.   My BBQ maxes out at around 575°F but I figured the specimen would be significantly hotter since it was directly above the burner.  I would shoot the specimen with my infrared thermometer each hour.  I measured temps around 600°F.  Its sort of a moving target because as soon as you lift the cover the specimen is exposed to ambient air and the temp immediately starts to plunge.  I got it as hot as I could without putting a flame directly on it. The specimens looked pretty good after the bake-off, but the slight separation line was starting to become a bit more evident on the original JB Weld specimen.  Otherwise it looked solid.  None of the specimens showed any sign of imminent failure.  They were all hard as rock and seemed to be holding up well.  The only significant visual change was the epoxies were getting darker in color. To see how the heat affected the water solubility, I threw them back in a jar for another soak.  The Extreme Heat product now showed no evidence of dissolving, but it swelled up.  It was lookin worse and worse for Extreme Heat.  It’s just doesn’t look like a good product to use in any sort of uncaptured application.  I think it would be OK in a threaded hole, or as a sort of filler/sealant between say my special exhaust insert and the face of the port.  But anywhere it isn’t captured, I don’t trust it. I did another test on the Extreme Heat to see if it becomes insoluble at lower temps.  I baked a specimen at 250°F for two hours, then placed it in a jar of water.  It didn’t dissolve, and it was still hard as rock after the soak, but when I pressed on it with my thump it popped right off the test angle.  I’m not likin that.  Here’s how the stuff looked.  I’m not likin the gas pockets.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/06/19 at 23:58:56 Now it was time for the gasoline soak.  I soaked the epoxy specimens in E10 for twelve hours.  No visible change.  They held up fine.  Still hard as rock. At this point, I was pretty much convinced that I would not be putting the Extreme Heat product in the exhaust port.  It is just too sketchy.  But both epoxies seemed suitable for the intake.  They could take the anticipated heat in stride, and they showed little inclination to separate from the substrate or swell when subjected to shear, heat, or E10.  It was now time to test for adhesion.  I included the Extreme Heat just to collect the info. My adhesion test uses two eye bolts with flange nuts.  The flange nuts were prepped with an abrasive cut-off wheel to provide a good anchor profile, then I cemented the two assemblies together and let the product cure for two days.  Then I baked the specimen in the BBQ at the appropriate temperature (450°F for the epoxies and 600+°F for the Extreme Heat). Here is an example of the anchor prep.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/07/19 at 00:00:23 Here is an example of an adhesion/tensile test specimen.  I want to see the bond between the nut and the epoxy hold up and the epoxy fail in the center of the joint.  That way I know the adhesion between the epoxy and the port wall should be good enough to keep the filler material in place.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/07/19 at 00:01:52 I used the High Heat product and started with a specimen that had no anchor profile, just the plated surface and serrations on the flange nut.  I suspended weight from the test specimen in five-pound increments.  The bond line failed at 50 lbs.  The flange nuts have a surface area of .26 square inches so that works out to 192 psi.   I did this test to demonstrate what I don’t want.  I want the epoxy material to fail, not the bond.  You can clearly see that the epoxy pulled completely away from the serrated nut.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/07/19 at 00:03:06 Now I started testing the adhesion using a proper anchor profile.  The original JB Weld had less than satisfactory adhesion, it failed partially in the epoxy but also pulled away from the nut in some areas.  It handled a weight of 60 lbs. and held it for 28 minutes before it let go.  That works out to about 231 psi.  I’d say this is pretty good stuff, but I would prefer better adhesion.  The epoxy will only be used as a filler material, it won’t carry any appreciable load.  I want to be sure it sticks to the port, so I am more concerned with bond than I am with tensile strength.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/07/19 at 00:03:58 The High Heat product failed exactly where I want it to fail, in the middle of the epoxy.  It also handled 60 lbs. (231 psi) but only for 14 minutes.  Note that you can’t see any part of the nuts, you can only see epoxy.  The bond was stronger than the epoxy material.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/07/19 at 00:05:14 The Extreme Heat product also failed exactly where I want it to fail, in the middle of the cement.  Unfortunately, it failed at a load of only 10 lbs (39 psi).  That’s just way too low.  I’m thinkin that the substrate and filler will constantly be expanding and contracting at different rates.  That will subject the bond line to cyclic shear stress.  This stuff is so weak that I think the brittle filler will start breaking up.  I won’t be using it in this uncaptured application.  Also note all the gas holes.  This is crazy stuff.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/07/19 at 00:07:24 Based on the results of my tests, I decided to use the JB Wed High Heat product for my intake port modifications.  Not only does it appear to have better adhesion, the fact that it’s a putty rather than a paste makes it much easier to apply and form into the shape you want inside the port.  It’s in my head right now, and it’s runnin good.  I have 94 miles on the epoxy mod and all seems well.  I pulled the carb and manifold off to get a look at how the epoxy is holding up.  Here’s how it looked after 94 miles.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/07/19 at 00:08:15 Here’s a shot from another angle.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 05/07/19 at 00:14:21 I know that 94 miles isn't much of a test but I figured it was prudent to make sure it wasn't falling apart before something ugly happened.  It looks good to me. Aside from some discoloration, it looks solid.  I will probably do another inspection around 500 miles.  I’ll let you know the results. For now, filling in the Dipsy-Doodle (DD) in the exhaust port will be on hold.  Flow tests showed decent improvements when the DD was filled in, but If I can’t come up with a suitable filler, I will never find out how well it works in the real world. I have looked at some literature on a couple of possibilities.  Blue Magic 8024 Thermo Steel is billed as “suitable for aluminum application”.  There’s another product, Pyro Putty 2400.  Do any of you have any experience with either of these products? Manley used to sell a product called 40180 Miracle Epoxy.  It was intended for exhaust ports.  I called Manley to inquire about it and the rep said they discontinued it.  I imagine because it can’t hack the heat.  I can find some venders that say they have the 40180, but when I try to order I always get “out-of-stock”.  Any of you have any experience with this Manley product? If any of you have experience (good or bad) with filling in exhaust ports with some sort of ceramic paste or possibly even epoxy, please let us all know the specifics. I hope some of you find this information useful.  My stage II head with epoxy modified intake port feels really good.  I am hoping to get it on a dyno soon, then I will have some hard data. Knowledge is power. Mike

Title: Re: Epoxy Test for Port Mods Post by verslagen1 on 08/06/19 at 09:36:38 It would be interesting to see if applying a vacuum would remove the porosity. That's certainly why you're getting low strength values as the porosity reduces the cross section.

Title: Re: Epoxy Test for Port Mods Post by justin_o_guy2 on 08/06/19 at 11:07:43 Stirring creates tiny bubbles Maybe spreading it thin on your mixing pallet and let it exhale, stick your palm sander in a vise and hold your pallet on it, shake the crap outta the epoxy, and of course, using anything from bondo to JB Weld, the first swipe has to wet the surface by pressing the adhesive tight into the surface. A vacuum would be a great idea. I've used compressors from dead refrigerators, and they are good enough to pull the A.C. system down on the car. I've used a retired breathing treatment nebulizer to bleed brakes, Be creative,, I tapped into the vacuum on the bike to suck a storage bag down to make some clothes smaller to fit in my saddlebags..

Title: Re: Epoxy Test for Port Mods Post by Armen on 08/06/19 at 16:36:26 Hey DBM, Thanks for all your hard work and sharing the info with us! FWIW, I used JB weld on the intake port of our 250 Bultaco 2 stroke racer in the late 80's/early 90's. The ports were crap, and the port to cylinder liner alignment was comical. Many races, and an AHRMA national championship in the 250GP class with never a problem with the goop.

Title: Re: Epoxy Test for Port Mods Post by DragBikeMike on 08/06/19 at 23:33:09 Armen, thanks for the info regarding the Bultaco epoxy job.  It's always reassuring to get input based on personal experience.  Sounds like your Taco was major fast and the JB Weld held up good.   Versy & JOG, the epoxy product did not have a porosity issue.  It's a two-part epoxy and it had ample strength and adhesion.  I used it in the intake port and it is holding up well.  The product with low strength and major pososity is a water base paste.  It's strange stuff.  I'm thinkin if I subjected it to a vacuum it might not cure.  I guess it's possible that if I pulled enough vacuum it would cause the water to flash off.  Not sure how it would set up like that. The interesting thing about the gas holes and porosity is that it didn't seem to develop those issues until I cooked it.  When I initially applied the Extreme Heat paste and let it cure for several days, I blended it into the substrate with a die grinder and porting roll.  Although it exhibited a sand-like porosity (sort of like sandstone), it didn't have craters and gas holes.  The big craters and gas holes don't seem to show up until I cook it.

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