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how many of you had your motors street ported and exhaust ported,and how long did you run the stock ecu until you had the car tuned, did the car react fine with the stock ecu, last who built your motors.thanks john.
Look what I found, in the brilliantly named "newbie's guide to modding the rx8"
Guideline: The relative "high power" limitations to the Renesis are largely due to the exhaust ports. They can not be increased in size by much since they are run through the side plates, between the oil and coolant passages, and the studs, etc... Prior RX-7s had the entire end of the rotor housing to work with for exhaust dumping. Adding exhaust ports to the housing is viable, though imperfect and makes the engine no longer a Renesis, rendering this point moot. Any high power goals will have to take this fact into account with some serious consideration. There are some methods of increased exhaust porting, though none known have performed flawlessly, usually introducing different issues that have to be addressed. There are also other points that produce capping effects on power, but the exhaust port size is the the one that people run into first and is the hardest to get around.
^ wtf didnt ask how rotarys work, ive been working on them for 17 years, was just doing a process of elimination with reply's for my own research, if i needed more technical detailed answers i just search for it duh!
the cow is still out to pasture on this one.. those who port and gain power, keep the fact that they dont increase timing very much to them selves. or at least there isnt' an abudance of sharing street ported rx8 information on this forum.
most will tell you it can't be ported much. i think they're right.
im an FC guy like you.. i've been rebuilding and porting the fc motor for some time.
the problem is around 230-250hp is the limit for the (1300cc)engine and mazda did everything they could to get power out, not leaving many options on the table..
yes there is bridgeporting, havent seen much info since bdc tried it. did that ever go anywhere?
and then peri ports, but neither of those are a street engine. they don't cruise. period. no thanks.. im a fan of cruise control.. then again i want my racecar with a/c and a nice stereo/heated seats/remote start.
you know what it takes to get 200hp out of an N/a FC engine... right? you already have that with the rx8, asking for more, is like getting the biggest cake in the store, and demanding you want it bigger.
EDIT:
so did some digging and you can get 30 more hp on the rene with a bridge... with gas milage cut in half or worse. enjoy.
Last edited by lastphaseofthis; 02-06-2016 at 06:58 AM.
To whatever extent you can port the Renesis, the factory PCM and tune can handle it.
This was my assumption, but it's nice to have someone knowledgeable also share that view.
Racing Beat tends to be conservative and realistic with their performance claims, but their street port dyno looks almost too good to be true. It shows gains across the entire rev range, with no loss at low RPM and large gains on the top end.
Has anyone else confirmed these claims? I have no reason to doubt RB, but again it almost seems too good to be true (unless your emissions and mpgs take a large hit?)
My own opinion of bridge porting is that I have never seen a BP Renesis actually last any longer than a couple trips to the grocery store. I could be wrong, but that is my own knowledge and information on the matter.
I agree with everything Charles said.
I would like to also add that the guys in UK are doing some serious bridgeporting that is apparently lasting.
Last edited by yomomspimp06; 06-22-2016 at 11:10 AM.
My own opinion of bridge porting is that I have never seen a BP Renesis actually last any longer than a couple trips to the grocery store. I could be wrong, but that is my own knowledge and information on the matter.
Mine is still running with over 70k miles on it... Power gains are negligible, and mid range is a little more peppy, but overall, not worth the potential reliability issues for nominal gains (5~15Hp at most). None have lasted as long as mine that I'm aware of either as you ave mentioned.
You will also have an issue with a pulse surge up the secondaries do to the introduced overlap. This causes the SSV to rattle like it's bad, and deposits oil / fuel on the valve. I have to pull it and clean it at least once a year. It's a maintenance nightmare, and I constantly feel like I'm walking on egg shells. I would recommend FI, NOS, or a motor swap before I would recommend a Renesis bridge to anyone.
Mine is still running with over 70k miles on it... Power gains are negligible, and mid range is a little more peppy, but overall, not worth the potential reliability issues for nominal gains (5~15Hp at most). None have lasted as long as mine that I'm aware of either as you ave mentioned.
You will also have an issue with a pulse surge up the secondaries do to the introduced overlap. This causes the SSV to rattle like it's bad, and deposits oil / fuel on the valve. I have to pull it and clean it at least once a year. It's a maintenance nightmare, and I constantly feel like I'm walking on egg shells. I would recommend FI, NOS, or a motor swap before I would recommend a Renesis bridge to anyone.
Am considering a bridgeport on my next turbo build so was very interested to read this .
Wonder what we could do to minimise these issues ...
Water injection ?
Bridge only 1/2 of the secondary port so it has less overlap ?
Some modification to the SSV ?
were all your ports bridged Red , or just the secondaries ?
Am considering a bridgeport on my next turbo build so was very interested to read this .
Wonder what we could do to minimise these issues ...
Water injection ?
Bridge only 1/2 of the secondary port so it has less overlap ?
Some modification to the SSV ?
were all your ports bridged Red , or just the secondaries ?
Just the Secondaries are bridged, so I guess you could call it a "half bridge." My other ports have just been shaped a little. I'm sure you could get a bit more gains by doing the primary and secondaries, but you're going to loose out on the low end and idle for another (I think) minimal gain.
Only thing I could think of with the SSV was to make like a duralin or polyurethane spacer and space it out a little. It's the dashpot arm that technically chatters. If you touch it with your finger, then it stops making noise. I never got around to doing it, and I'm really bored with the engine. It's going 20b as soon as the new adaptronics ECUs are out that are full standalone with OBD2 support (I was given the estimate of next year by the NA rep). So I'm not going to mess with it anymore than I have to right now.
Waste of time and money. Our local buddy that paid big bucks for a Darryl Drummond (Google him) rebuild that made 263HP at the flywheel (engine dyno) @8200RPM and 181 ft/lb and it is not ported. Of course no one knows his rebuild secrets, which is why his builds ae so sought after in the racing community. But from what I know he rebuilds them in the same manner that any high end race engine builder does.
My engine is ported but I don't feel it added anything. A street port is kind of a "why not" thing as long as you are conservative but a bridgeport is just as pointless with the added benefit of reducing reliability.
Waste of time and money. Our local buddy that paid big bucks for a Darryl Drummond (Google him) rebuild that made 263HP at the flywheel (engine dyno) @8200RPM and 181 ft/lb and it is not ported. Of course no one knows his rebuild secrets, which is why his builds ae so sought after in the racing community. But from what I know he rebuilds them in the same manner that any high end race engine builder does.
My engine is ported but I don't feel it added anything. A street port is kind of a "why not" thing as long as you are conservative but a bridgeport is just as pointless with the added benefit of reducing reliability.
I would honestly have to agree. I'm done with the Renesis outside of a consistent daily driver. Modifying them is almost pointless without some kind of XTREEM!!!11 build that in and of itself is completely experimental (Like the build on the semi pport that died several months ago).
I was considering a multi piece eshaft with the center bearing, and full pports for an "8 port" setup capping out at around 13k RPM, but it's not worth the cost, and part availability just isn't there. I can get the same or better performance specs out of a 20b with less risk, more reliability, and less cost.
Yeah it really comes down to how much time and money you want to waste. For some it's fun to experiment and that is cool but we know what is possible already in terms of a rebuild without porting so why bother?
Plenty have tried bridge porting and most who claim any gains from it never back up those claims. Of course you have the guys (the guys on the Aussie forum come to mind) who dyno after are build and bridgeport/tune and make 220WHP and then claim it's all do to the bridgeport but those are pretty rare and rarely heard of ever again. There is a shop in the UK that claims it is the thing to do, but of course they never prove anything, you just have to take their word for it.
reddozen, I have always appreciated your honesty about it. It's hard for many to be real about something and admit it may have not been the best route after spending the money. We always want to justify it to ourselves I think,
I was butt-hurt about it for a little while, then I got over it. It's the price you pay to be a test mule. You pay more because it's not very "standard", and the results are unknown going in.
I will say that some that have driven my car claim that it feels a lot different and that "it should have come from the factory this way". I've also ridden in close to stock 8's that feel much faster... either way, the gains are so small that they leave room for guesses. That alone should tell you that it's not really contributing to anything if it's not significantly noticeable.
It doesn't even Brap ... not enough overlap on my setup sadly.
So no one has dyno numbers on a 'properly'done street port or bridgeport?
Lets consider the fact that freshly rebuilt engines with stock ports will dyno between 190-220HP. That's a 30 HP swing... that being the case, it will prove nothing about the 5~10hp that the porting may have helped you with. So to answer your question from a bridge port owner, it's not worth wasting the money on the dyno sheets for a power increase that you cannot feel the difference in. Plus the bridge porting create more maintenance problems that go along with the lack of power increase. It's just not recommended.
It's just like Charles said, it will help out your torque curve a little in the mid range, but it's not a "major HP" improvement. If this a route you choose to take, be very cautious of the quality and who does them, but if you're wanting actual power gains, look into a turbo, supercharger or NOS, and not porting.
Thank you for all your thoughts! I probably will be going with a street porting/cleaning/polishing route due to instability of a Bridgeport. Its one of those, "if I'm getting it rebuilt why not?"
Did some reading on the forum...good info. Thanks.
02-04-2016, 05:10 PM
street port exhaust port owners n/a
... not enough overlap on my setup sadly.
