when your polishing the intake ports are you assuming that the plastic diffusers under the injectors are mixing the fuel and air well enough? or did you leave the port a little rough for a good mixture?

i ask because i've heard since we have the diffusers we can polish the crap out of the intake ports but i've also heard it the other way around. i wanted your opinion on it since you seen like you've ported one or two times before

 

There are arguments either way. Some say to leave the runner surface rough to cause disturbance around the walls, which encourages laminar flow (think about golf ball dimples). Others say that smooth is bet for airflow. I've done either way in the past and honestly, have not been able to tell the difference. Then again, all the engines were different so a direct comparison isn't possible.

You are correct that the diffusers are instrumental in getting low load fuel mixtures. Mazda has continually worked to improve the diffusers and in the RX-8, they are actually little pipes that extend into the manifold and blow on the injectors. They are VERY important. So when porting the runners, don't mess up the diffuser holes.

At this point I don't totally smooth the runners, I just remove the casting flash with a quick hit on the grinding stone and then a few seconds with a sand paper roll.

 

wow! 24 000 posts... Keep the good work!

 

any updates??

 

I have the next episode almost ready to go. I won't, however, be in my shop for a while because of the stupid holidays. Which sucks, because not only do I want to work on the Cosmo, but I also just built a small 12V air compressor on which I need to rework the check valve in the cylinder head before I can use it.

I hate Christmas.

 

Me too Christmas is getting in the way of my car being completed..

 

+1

It's even worse that we don't have extra days off and it's too cold here to work on my 7

 

It's a Festivus miracle that I now present Episode 8 of my Cosmo restoration. Now that the engine is fully ported, episode 8 deals with the final prep of those engine parts before engine assembly. In this episode the rear iron and water pump housing are tapped for sensors and fittings, and then all the engine parts are glass bead blasted and then painted with POR-15's engine enamel. Also included: adapting S4 water pump housing to older 13B, tapping rear iron for turbo coolant feed, masking the parts for blasting and painting, final soap and water wash, watching paint dry.

http://www.youtube.com/watch?v=v-0Yl_Jlx1w

 

"what the hell would i do with an 18" *****?"

LOL

♥i love you man♥

 

Nice video man

Is there a reason why people always paint their Iron and rotor housings a different color?

 

Contrast. Otherwise there is a solid lump of single colour under the hood. I might do a single colour engine one day. This one I just wanted to look good, not rust, and be easy to clean. the engine in my RX-7 is more flamboyant in colour but it is harder to keep clean. The manifolds are going to be silver as well.

 

Great job man! I had a question a couple of builders I know told me they don't like painting the housings Because it holds heat . What is your theory in that .? I don't got mine painted because of that reason .

 

It stands to reason that any coating applied to the outside of the housings would decrease heat dissipation a little bit. However, compared to the surface area of the radiator and oil cooler, the housings are minuscule very little heat is lost through them. So really, it doesn't matter at all whether they are painted or not.

I'm surprised that engine builders would be fooled by this myth.

 

personally..i dont like to paint housings due to the fact that the paint chips off over time...aside from that paint everything!

 

Powder coat them like I did and you don't have to worry about chipping.

 

Wow that's nice

 

Not sure why they think this is true but they never paint them and they feel like the cooler the engine the better it is .They said if Mazda thought it can be painted it would of been. I learn not to argue since I don't build rotary engines ( I'm dying to build one doe )

 

I think Mazda didn't paint them because of the cost savings.

 

It really depends on the prep and the paint you use. Housings and irons should really be blasted first to remove every bit of surface dirt and rust. The blasting would also etch the surface and provide the proper "tooth" for paint to grip. If blasting isn't available, then things can be sanded with 80 grit but that is far more time consuming. Or the parts can be acid etched with phosphorus acid. The next key is that all the parts must be absolutely and perfectly clean.

Remember that the parts store engine enamels are pretty crappy as far as paint quality. They contain a high percentage of solvents so that they spray easily and dry quickly. High solvent paints require a lot of coats to get coverage and don't tend to adhere very well. Solvent evaporation also leaves pores which allow outside contaminants to penetrate down to the bare metal.

A high quality two part paint eliminates most of this. I used POR-15s engine enamel which is a premium paint with a very high solid percentage. Because it contains far less solvent, it also takes a very long time to dry. There is a 24 hour period needed between recoats and it is fully dry after 5-7 days. But when dry, it looks and feels like powder coat. POR-15 also makes a 2 part topcoat called "Hardnose" paint which is basically indestructible. It will almost blast off but really can only be removed with a grinder. My wheels are painted with black Hardnose and nothing short of a curbing has damaged them.

I've powder coated before but am always nervous about letting my stuff out of my sight. For example, what if the person doing the blasting didn't bother to totally mask a machined surface and accidentally tagged it with the blaster? I can get the same results "in house" with POR-15 paints.

Mazda didn't paint the engine because these days, no major manufacturer is painting engines. Painting an engine translates into time and money which doesn't benefit the manufacturer at all. You'll notice nothing in the engine bay is painted. Steel parts are generally plated and aluminum parts are left bare. The labor associated with painting each rotor housing and iron would be significant.

 

great Now I know .. I may just leave bare aluminum and just try to shine it up ,if it dont look so good is getting some paint,,

Thanks guys,

 

Nice work Aaron. Are you doing this in your spare time like after hours at your shop? How do you find the time to be so detail oriented?? I know you said you don't have a life, but with all the hours you put in, plus 8 hr work days, I'm questioning if you even sleep! lol. Again, great work... the video logs are very entertaining as well.

 

Yes, I'm working on the car basically evenings and weekends. Note that the shop with the car is different from my day job shop, which is as a computer tech. I usually try to alternate days between working on the car and doing other stuff like my website. Being detail oriented is in my opinion the only way to tackle a project like this. Get the big picture of the overall scope, then micromanage each task and concentrate on the details of that task. Step back and go big picture every once and a while to make sure you aren't detailing yourself into a corner (for example, painting the engine bay before drilling all the holes for cabling). Also remember that I'm editing the footage to make the process smoother than it it may appear in real life. None of my blasting footage included the 30 minutes I spent unclogging the blaster after some moisture bound up all the blast media.

 

Aaron your attention to detail has helped me out in my own resto, being that this is the first time I have taken on a project like this. I need to sit down when the car gets back and start micromanaging all the little things.

 

actually the pre 78 engines, like the original engine from this cosmo did have had black painted irons. the early non nitrided engines got black painted irons. they stopped painting em because the nitride coating gives enough rust protection.

the aluminum parts never get painted in an OEM application, as aluminum doesn't rust.

Aaron; i can't believe i just watched a video of you watching paint dry, quentin tarentino you are

 

yeah I figured the footage was edited, but I didn't realize your occupation was in an unrelated field. I have learned to be a bit more detail oriented over the years and various projects and it is only through watching builds like this that get me to disregard my old ways of "ugly, but works good" . Again...great job, and looking forward to seeing footage of that engine being assembled. Best of luck moving forward.