Yes, i know you have no idea if i can, or cant make fiberglass valve covers… Will the cured material be viable for such a part. Considerations im thinking of are, contact with petroleum products, heat, vibration etc…Thoughts?
Ps, poly resin.And i want to used woven heavy mat. Can i Dye the resin or mat black?
I should check, but I think some vinylesters will be able to cope with 100 degrees C oil
Polyester isnt very good stuff not to mention it likes to skrink when curing. Yes you can dye resin
How bad is not very good? Its brand new stuff that i bought to make my bumper. Marine grade(if that means squat) Polyester laminating resin. Is Poly, Poly and thats that?
I’m not sure that the HDT/Tg of polyester resin is high enough for a valve cover. I’d think that vinyl ester might be too close as well. I’d make them from a high temp epoxy.
Ole Dutch (ranchero.us) said there is a post curing bake required for some epoxies…I think, does that apply to your statement?
What happens if it gets too hot? Sag, droop, soften and deform? I dont imagine itll liquify…but thats why im here asking you fine people;)
To raise the Tg of an epoxy resin one must post-cure the resin at the appropriate temps. The Tg will also go up with PE and VE with an elevated temperature cure. The max. Tg is determined by the chemistry of the resin.
If the Tg is exceeded the resin become soft and rubbery. If the temps become too high the molecular bonds within the resin can be damaged and the resin will become very weak.
Most of the VE resins have high temperature resistance and usually have most chemical resistance. DION9100 which I use, has HDT 105C and does not require posture. We have successfully made exhausts with it and carbon fiber and laminate easily resists 150C.
Note that the HDT manufacturers give for the resin is based on the lab sample reingoced with fiberglass mat. The measurments they do for determining this are based on resisting the load-force during the temperature increase. If you use wowen fiberglas the laminate will resist more and if you use carbon even more, so the reinforcement also affect when your part will start losing shape… Now, you basically have no forces acting on the valve cover and temperature will probably not go over 120C so a quality VE will do.
HDT samples are usually done on cast resin bars without reinforcement.
I thought so as well but then a technician from Reichhold told me how it is done after discussing about how some laminate that I used on a race bake withstands silly temperatures…
Maybe some one can dig out some info from an institute that does this? And i believe there are different methods as well.
The documentation for DION 9100 states that the samples used for HDT testing are clear castings that have been fully post-cured. They don’t list any HDT results under the laminate properties.
Adding fiber will increase the HDT over a raw resin sample. If you have two samples with the same amount of fiber, but different resins, the sample that has the resin with the highest HDT will yield an FRP with the highest HDT. This happens all the time with high temp resins. Many high temp resins can handle 300F with fiber even though the Tg of the resin is only around 250F. I can testify that many of these 300*F high temp resin are still prone to distortion around bolt holes and high pressure clamping points when the Tg of the resin is exceeded. For this reason I like to make sure that the Tg of the resin exceeds the planned operating temperature.
Maybe a vinyl ester is sufficient. I’d have to do some long term testing before I would commit to production.
And besides bolt point distorsion you get the fiber print on the surfice with resin which is not comepletly cured-or postcured (if that’s the corect term?) Which can be a problem for parts of aesthetic purpose…
How hot do the valve covers get? 100C tops, I guess. oil is seldomly hotter. My concern is more in the chemical resistance.
What if i use a VE resin with some twil weave carbon fiber? Does the reinforcement material change the temp resistance a noteable amount, or just the strength? I can afford enough carbon mat to do a set of v-8 valve covers…i think…
Edit; I was thinking of using furniture grade plywood for the gasket/mating surface. Where as, i would cut out the shape of the valve cover gasket but make it about 1/2 " thick so i could have a nice stable mounting surface, and not have to build it up so much with the resins or mats.
You might look into basalt fabric. It will take high temperatures.
I honestly think it would be an expensive project for you. Is it possible? Sure! Will resin hold up to oil… I think so… Especially since there are many paints and sealers that offer a chemical barrier that will work great. In that respect you need a resin that will hold up to high temps.
General purpose pe boat resin will probably fail quickly…
But there are plenty of options out there…
If your planning on winging a one off set… Maybe for cost intensive purposes it might be well advised to start smaller and work your way up to that sort of project. No doubt carbon vc would be sweet but… It’s not gonna be cheap to make a solid well built set.
This is my two cents.
There’s a build thread by twodollarDoug you might wanna read and he did a fantastic job his first go around with infusion. He made some carbon carb hats for his Porsche that turned out nice. The thread might give you an idea what even a simple part might require.
Good luck!