RX7 Specialties (rotaryengine.com) CNC exhaust porting
 

Looks much more precise than the die grinder porting I've seen.

Does this kind of porting actually advance exhaust timing though? It looks like the enlarged exhaust port (at the wide end) doesn't actually go all the way through, and "slopes" to avoid the water jacket so that the opening itself is not actually any larger (though perhaps flow is increased).

Doesn't address the issue with the port-runner transition. May even make it worse.

Also, his explanation of the carbon nugget from the exhaust port shelf doesn't seem likely to me. If exhaust gasses are flowing out through the exhaust port, how does the carbon fall back into the chamber against the gas flow.

Yeah we'll have to see if they ever post dyno results.
The rotary community is simply awful at information sharing. I'm super curious how Rotary Innovations closed off its side exhaust ports on their funky dual-intake allegedly 271 flywheel hp semi-PP Renesis.

A meticulous build and proper tune of an unported Renesis can get you to 260. Doesn't sound like all their extra work has gotten them much.

Looks like quality work on the machining, but without the bare minimum of dyno results before and after porting (same irons, same hard seals), it is hard to consider it anything other than BS.

I have watched a bunch of their videos. All of their work appears to be top notch. if I ever get a hankering for more porting, I would definitively let them do the rough ins on some brand new sideplates

Unported Renesis engine:


https://cimg4.ibsrv.net/gimg/www.rx8...5c441200c.jpeg

Just wanted to comment i live in calagry and have his exhaust and intake porting, initially ran on a n/a and felt no diffence on the butt dyno maf readings within 5 gpm before and after, will be turbo soon hopfully will help a little

It wont make much difference on a turbo setup either....... As with all modifications you can believe the people that want to sell you something ...... or you can believe the people who have been there done that.

Figued as much as have read your turbo thread, will be interesting to see what i can do with a top mount efr 8374 tho

That will be interesting. The efr9174 done by Turblown didn't produce anything like the spoolup it should have , 8374 should do better ...but will it do better than mine? Will follow with interest!

Not or to threadjack but I’m also looking forward to seeing the 8374 and what it does. I picked up a 7670 and getting a rebuild by goopy so I’ll be jumping in headfirst soon as well

I almost went 7670 will be interesting to compare look forward to your build, i just need a few more posts and will start a thread

This will be really cool ...been keen to see what both of those turbos will do on a Renesis.

i see no power gains from this exhaust porting, just better flow and cooler exhaust temps and almost no carbon build up, thats about it.

All you’ll see is a few hp and at the expense of side seal life/effectiveness ...

just to clarify, the overall issue is that there isn’t enough material thickness in the area around the exhaust port where it’s needed to result in anything useful. There is negative exhaust-intake port timing overlap that you can’t do anything about. This is what makes the Renesis unique among most combustion engines and tuning the exhaust mostly wasted work.

All you can do from an NA perspective is to make the exhaust as free flowing/restriction free as possible. For FI doing much more than clearancing the port opening to account for high temperature expansion on the entrance corners is going eventually result in excessive blowby imo due to side seal degradation.

The heat factor of FI alone is abusing them badly. Which they already have long term issues for NA. Taking support material away only exacerbates the situation. You instead need to focus more on proper design and execution of the overall package rather than trying to squeeze a fabled golden egg out the ugly Renesis duckling. See Slash128s build.

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I self ported my exhaust ports and runner transitions using Racing Beat's template ... incorporating RX7 Specialities theory. Yes, this porting does advance exhaust port timing b/c the side seal sweeps past, i.e. opens, the exhaust port leading edge allowing exhaust gas evacuation earlier in the cycle. I won't have a direct comparison b/c my engine wasn't ported pre-turbo, but expect to see better exhaust flow and cooler exhaust as Jorx7 indicated, both of which are advantageous in a turbo application. :yesnod:

As Team suggests... everything must be considered "systemically". So, I agree 100% one has to focus on "proper design and execution of overall package", which I believe can incorporate thoughtful porting. No?

Currently resolving radiator / coolant temp issues in our 90F May weather... Once temps are managed... I should be able to get good data on my currently ported vs. previously non-ported turbo system.

Edit: rebuilt engine with porting generates nearly identical HP/ Trq @ 9 psi as the previous non-ported engine @ 10+ psi.
- See build thread, post #380
https://www.rx8club.com/series-i-maj...268497/page16/

Couldn't agree more ............... FI porting does nothing useful . The only gain I've ever seen,from extensive experimentation, was to open the outer exhaust ports before the siamese . This improved my turbo spoolup by 1000rpm but it will only do this on a manifold that favors the outer ports.

Well, theory is well... theory, but won't argue with results of thoughtful experimentation... Team & Brettus. :icon_tup:

I thought it made sense to try exhaust porting since I had my engine apart. Time will tell... :dunno: but I'll expect my findings to be consistent w/ yours.

Btw...I did port my end irons slightly larger than the mid iron. We'll see...

well to open the thread again, I got their porting done, along with a street port on my 8, still within the break in period, but it definitely pops more so its flowing a bunch more air. I'm also running versatune, so ill be getting a dyno tune here shortly, so numbers will follow. As far as the craftsmanship, its top notch. everything is super clean and professionally done, and i got the rotating assembly balanced, i cant even feel this engine idle, if it weren't for the sound it would be hard to feel it running. 10K rpm here i come.

Don’t be too disappointed by the results

I'm not expecting miracles. Just slightly more flow, and maybe actually hit the claimed 230hp

I'd love to check out your set-up sometime; I'm in Sherwood Park.... I've been turbo'd on a GReddy kit since 2010 and I am starting to do my homework as far as rebuild and upgrading for more boost is concerned (planning to get turbo upgraded by BNR to hold more boost all the way to redline). I've chatted with Adam at Rx7 Specialties a little bit on the phone and via email. As far as I'm concerned, this is the shop I'll be using when rebuild time comes along, definitely interested in having some mild exhaust porting done while he's at it. Also considering studding.

Ya if you are down this way send me a pm and we can meet up. As far as adams concerned hes been great i had a odd oil seal failure after 1000km causing misfing he helped me diag and rebuilt the engine for free again with all new seals. As for studding he didnt recommned for these power levels.

so figured id add in,to my previous post. the port job feels significantly quicker, in fact i put buses on a 350z. The 350 driver also told me that there was also a 3 foot flame out the exhaust. so going from a 7 bar engine to a fresh rebuild I'm sure is a definite feel increase coupled with a lightweight flywheel and balanced rotating assembly allowing it to hit 10k rpms doesnt help any. i cant wait to see what it actually hits down to the ground, but so far im extremely happy and would give adam's porting two thumbs up. also with the huge exhaust port when the VDI opens, it SCREAMS. Significantly different rpm sounds along with idle sounds. Everything i was looking for without a bridgeport.

There is a reason why people that have been around a while are skeptical .
1/History shows that this kind of mod does little
2/History shows that people get all excited and want to justify their choices
3/History shows us that others also get excited and rush in to do the same mod cuz someone said it works
4/History shows that when tested properly on it's own with no other influences that nine times out of ten the mod did nothing in the first place.

So yeah , see what numbers you get as compared to a good stock engine and then and only then tell the world how great it is.

i had my engine built by them last year. bought a new oem engine from them, since they had one in stock, so saved me shipping and time instead of getting one from mazdamotorsport which was backorder. then got the cnc porting for intake and exhaust, rotating assembly balanced, rx7 apex seals mod, oil mod. the build took longer than i wanted, because he had to wait to send the rotors out to cut for rx7 seals in batch to reduce cost.

https://cimg4.ibsrv.net/gimg/www.rx8...483511951.jpeg

I was put on impound Dyno at the track last month and it made 210 whp on a slightly detuned map which got me a DQ, lol. It was a Dynojet

I’m sure the mini clutch helped

not sure how much hp gain you'd see on dyno from mini clutch, since the rpm ramp up is pretty slow on the dyno, unless it was done in 1st gear.

No, that’s just about what I’d have expected the difference to be. You not only reduced mass by over 50%, but also reduced the mass radius substantially for what remains. On a high rpm, low torque engine that matters.

There are some theoretical arguments on the web making your claim, but real dyno tests prove otherwise. The typical street ltw flywheel deal is lighter in mass, but not so much in inertia. What you have is substantially different.
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Awesome dude. That’s good to hear these little Renesis can compete with the good old vq engine in a straight. I have done all bolt on mods (bhr midpipe, rb headers and catback and RB ram air duct with k&n panel) have the 1.05 Versa tune flashed. Occasionally get flames. I need to find a tuner or a dyno place before I decide to destroy and rebuild. See what the stock engine can take before i do rebuild and port. In the meantime hopefully we can dyno and compare the results. I know the results would be unscientific and inconsistent based on engine life and care etc., but it will be something to at least look at for shits and giggles.