KYLE MOHAN on Why my BRIDGEPORT HYBRID RX8 only Made 100HP 

Sooooo i dont want to go TOOO deep into the rabbit hole, but welding cast iron is very tricky. Because of the higher than normal carbon in the iron vs steel, there is a higher percent of carbon that is drawn up into the weld metal and to the heat affected zone. This causes the weld spot, calling HAZ for future reference, to become more brittle and can be even easier to crack. The best way to weld cast iron is to clean the haz spot by grinding the cast skin off and cleaning with mineral spirits, then slowly bring the cast iron up to a suitable temp which depending on the type of cast iron can be between 100-400C, shielded metal arc welding would be the best route for making the weld with nickel based electrode to help reduce the pre-heating and HAZ cracking. Then you have to let the weld cool gradually, not rapidly. you can accomplish this by placing it into dry sand after the weld is complete. Like i said, its tricky, but can be done. I just worry that welding creating a heat affected zone right at the spot you are trying to prevent cracks from forming is gonna coerce the iron to crack vs prevent the crack. Just my 10 cents. would say 2, but we are waaaaay past 2 pennies at this point XD

I am currently rebuilding my Renesis and this series is teaching me a lot! I hope you guys learn a lot from this series so that maybe I can follow in your footsteps.

Thank you for this video and information. So much bs and misinformation behind the hybrid and the rotary community. Keep it up and flowing.

I'll get that video uploaded as soon as I can tonight, I'm actually working on my hybrid right now. Fun fact, somebody already sells an RX7 intake mani adapter for the Renesis

lap them housings together with valve grinding compound. You wouldn't put a piston engine together without honing the sealing surfaces. People will mention nitride coating but lapping the plates together removes .001 or less of the .003 of coating. Even Kyle Mohan takes off .002 on some is his housings with a lapping table.

I was hoping that the hybrid was the cure for my rotary disease, but clearly is not the panacea I was seeking. So it will have to be a pp for my track car and perhaps a small turbo for the rx8. I saw that blackstar motorsport had the front housing issue you are talking about with the lug.😊

I wonder why there are so many dislikes when this video answered a bunch of questions people had

Doesn't properly studding the block solve the iron Cracking issues ?

It's exhaust port timing. The gsl exhaust ports have different timing to the msp ports

I would be interested to review the Mass Airflow sensor values in ECU datalogs, if you have that. I think it would be useful to know if the flow sensor says the hybrid engine flows significantly less CFM (or grams/second or whatever) compared to the stock setup. The MAF sensor is basically a little flow bench inside the engine bay.

Kyle is 100% correct. The exhaust isn't gonna be much of an issue. The rotary moves too fast for exhaust pulses to come back through tubing. The reason everyone seems to notice power changes is because 10hp is such a large percentage of the available power it seems like a big impact, and it is. And you can easily see fluctuations of more than that just from temperature changes and fuel quality. The restriction in a rotary is always fuel first, then air. The reason the 12a is so easy to run is carburetor goodness. It allows for self balancing for the available air. Once a computer is introduced, it is looking for specific volume of air and fuel and strictly controls that. Rotary engines have nearly unlimited capability from their lack of valve train and ability to process fuel and air quickly. The cross sectional area being similar doesn't equate to equal volume. As you expand a circle, the area grows logarithmically, so the carbs flow essentially the same air as the throttle body that's only marginally smaller. But they can provide twice as much fuel. Your restriction is fuel. Rotary will eat all the air you can force in, why it is so happy under boost. Cram more fuel into it, fuel makes the power.

Try using lower compression rotors. The Renesis block isn't the problem, it was already proof with the Landspeed Renesis engine pushing 600whp on a stock block just with rx7 rotors, meth, and a huge turbo. You will save some machining too :)

Man this was awesome content! You are on fire the pass couple months! Definitely on RAD time!

Try TIG brazing around the boss area, less heat, but preheat is necessary.

How about using individual throttle bodies or a carb?

More talking with kyle would be super cool

Like I said in a couple of the last videos - use the peripheral exhaust ports for a turbo, and the center and side ports for a wastegate. I’m sure in THIS case it would work better than that Brett guy on the forums from like 10+ years ago. If this doesn’t get any traction here, I’ll stop suggesting it. Thanks for looking!

LETS GOOOO! KMR Baby!!!

This is the collab I've always wanted

Great stuff. Awesome video

i made a aluminum plenum for my rx8 turbo renesis and made 365hp294tq with 14psi and enjoyed for years

I had the pleasure of driving a low mileage, well cared for Mazdaspeed RX8 (very rare). The stock renesis definitely makes over 200HP. I'm really hoping that if I watch enough RU-vidrs working on Renesis motors, I might be able to convince myself to pull the trigger on an RX8. I'm really loving your channel dude.

** For combustion engine, exhaust gas only require 65 to 70% of the intake airflow to ensure efficient combustion, proper scavenging exhaust gas removal, and gas velocity to improve overall engine efficiency.

years ago i used 2 ford 5 liter throttle bodies on a home made intake with a street ported 13b 6 port we made between 160 to 180 HP.. I think you guys are being stingy with the air intake volume ..I would use a lot more intake air(BIGGER ) I have a 12a I built with a Total Needle bearing e shaft and rotors the intake is a h Racing Beat Holly with an adapter to use 2 - sequential 44mm Down draft Webers..these Engine need Air..in and out.

I had two thoughts in regards to the exhaust manifold. 1, could a "manifold" that vaguely looks like the plenum section of an R32 GTR intake manifold (especially the aftermarket ones), with the plenum right against the flange with maybe some small tabs welded in to direct the flow? Kind of like a log manifold, but a bit "gentler?" 2, how hard, within the confines of the RX-8 body, would it be to make two cone shaped "runners" that get all of R1's ports separated from R2's ports, but all related ports are within the same cone, and then do a 2-1 header from there?

You guys are silly. You added back in the exhaust overlap while adding so much exhaust port/runner area the exhaust exit velocity dropped in half and you are wondering why the engine suffered from exhaust contamination.

Mr. RAD, you’ve outdone yourself with this video! In the name of all the passionate people about the spinning dorito I would like to thank you very much for sharing all the facts and all the info. You did what many of us just imagined maybe in our wildest moments, and you’ve managed to have the discussion with KMR basically the one of the fathers of the hybrid. Mad respect!

Too much port timing in the 5-6 ports on the closing and the middle exhaust port communicating. In the s4-5 na motors we see that the ports already close too late the rx8 closes even later which works without overlap but once you add it

Always love a good rotary tech talk. I just built a half bridge old school 13B NA and I'm still slowly wrapping my head around the effects that port overlap introduce and what actually causes the oscillation we call the brap. 6:05 Mr. Rad mentions unburned air/ fuel mixture being wasted into the exhaust area via the path that the port overlap introduces - would this be the case for a N/A setup? I always thought of it as the exhaust charge sneaking upwards from the exhaust stroke area to the intake stroke area, since (I think) it's got more pressure due to exhaust gases still leaving - polluting the intake charge a bit which is what causes the brap (again I think). Turbocharged and in boost I could definitely see it going the other direction.

Videos like this are the reason this is one of the best automotive channels in RU-vid 👍 As far as reasons for low power, BP and stock intake probably weren't doing you any favors. Stock ports world be a better match for stock intake run by a stock ecu. ITB's/carb would probably be a better match for a BP.

HI there fellow rotor men I have to ask can you help me ? First i have to say that renesis bridge port hybrid that rad was experimenting with was never going to have power gaind when running half a stock exhaust and running a std intake manifold.. true ? If pp exhaust is introduced to the engine dont we need to introduce pp to the intake aswell as run esentually 2 raceing intake manifolds 1 for renesis' 1 for pp and 2 racing exhausts 1 for renesis and 1 for pp and huge amounts of modified fuel supply ? . 13b kangaroo..

Speaking of intake. Kyle pretty much is saying the same thing I did weeks back. Did you ever happen to disable the VDI on the intake on the butt dyno runs on the hybrid? Remember that I explained that since you now had over lap on the exhaust, that the over lap would effect the bounce back pulses of the intake. Disabling the VDI may have helped gain some power because now the front and rear intake runners stay separate throughout the full rpm band. The vdi of the Rx8 intake was designed to work with a non overlap exhaust.

hell yes! im super pumped about this video. some blanks finally filled in

You might want to rethink using rx8 high comp rotors, there known to be a failure point. Use rx7 rotors and dowel err up.

Must of been ace having kyle for a chat would be wild to ignore his thoughts and input mazdatrix would of spent some money on there hybrid haha! All the best on the next iteration man stay rad!

I got a Renesis hybrid I'm trying to get running got an 48ida tb on a gslse intake with a adapter from jdlmfg. I Designed a upper intake manifold and 3d printed it to turbo the engine. Haven't ran it on this setup with a standalone. But my engine does run on stock intake

*Would it have been easier to merge the end ports and the housing ports for each rotor, and then have center be separate, like the stock RX-8 headers?* That way you have it still running 3 to 1. 2 to one, right off the block, for each rotor, then 3 to 1 like normal.

Try tig brazing with silicon bronze to reduce heat input to the cast on the iron or if you don't want to buy a tig I'd lend a hand for science

Can you confirm the auxiliary sleeves were opening?

Do you have a number i can ship you what I did to my hybrid rx8 s2

I think a standalone ecu would fix all of the issues with this engine. Control of the intake actuators, injection timing, and ignition timing is what you were missing with that setup.

The seals organizer at 7:25 is really cool, I haven't finished the video but I'd like to find where to buy one of those.

Hey, what about to use some type of leaf valve, like in some 2t engines

Ya need to get the rotors machined to fit fd apex seals rx8 seals ain't designed to run across a open port exhaust

Mr Rad, when do you think we will see the hybrid back together boosting?

All that matters to me is that you love it. But…. I do watch the Hallmark channel WAY too much.

Im excited for the off-season upgrades on the rotary colt

With solid dowels you will need to run external oil lines- pretty easy to do.

Me and my buddies building a rotaries down here in Joplin Missouri at The Rotary doctors for years

Can we get an updated videos on rotor assembly and engine build

ECU dueling sensors?

Loved to know how the cars will be going!

You can braze cast iron (hardbrazing)

19:01 aren't there N/A drag 13B's with full PP making a LOT more power than 270rwhp?

Throttle body makes little difference to power out put. The throttle body is only. A restriction if the engine needs more air . On the hybrid, I've used stock intake and made a missserable 150hp at wheels I used a 50mm ida throttle body ( we cast an ida intake for the renisis) and made whopping 157hp at wheels all tuning was with haltech elite 1500 ecu on pump fuel. I tried long tube headders short headders even tried bridge port with Semi pp and just the semi pp The results were always disappointing. Sometimes with in 1hp of the previous I welded up renisis side port and ran just the gsle exhaust port thinking I'll have to make the same power as a 4 or 6 port fc block would 220hp easily. Nope made 169hp at wheels. So I pulled the renisis rotors out and welded the intake ports so I could use fd rotors and there is where the power came back 205hp . My theory is the rx8 rotor is limited by the volumetric efficiency due to the compression ratio of the rotor Unlike a piston engine when you raise compression in a rotary engine you loose cylinder volume . After this I pulled the rotors out put them in an fc block with basic bridge port same throttle body same style ida intake and made 227hp As seen in my video. With this I then went back to the renisis block welded the ports up bridged the intake and used s4 turbo rotors in it And fed it 25psi boost with a g42 turbo on e85 fuel It made 630hp before it cracked the front plate down through the water inlet to the front gear. The long and short of it all the renisis is a highly tuned engine from mazda that is at peak power in the form released. And wasted time and money

Air speed ratio is out of whack

E85?

Awesome stuff as always man!

I'm surprised at how nonexistent flowbench data is for rotary engine parts, with piston engines that data is everywhere.

Honestly I think the renesis engine is way overrated for HP, my 85 gsl with the 1.1 with just a racing beat long tube header and exhaust would beat them easily in a race, that motor was rated around 100 HP and with the header I believe it was actually putting down about that to the wheels, with weight reduction the car was pretty fast and handles great.

nice!

I'd love to know if the SSV and VDI systems are necessary on the hybrid and if not, where to get a lower intake manifold that doesnt have that system

Love your videos man

HYPE

Maybe an idea... RacingBeat makes a Renesis to FC intake adapter. Use a FC 6 port lower intake with the REW upper intake and throttle body

The ports really need to be tuned intake and exhaust. The exhaust should have the center joiner either plugged or plumbed in at 2x length of the singles or else there will be lots of pulse issues. Same for the intake, the overlap issue will be excessive on a short runner. Run long tuned inakes on a 4 port should work ok up to 9k. Just my speculation. Had my 13b bug with 12 foot 3 inch exhaust and it was amazing. Wish I could had it dyno'd.

Rotaries are INCREDIBLY inefficient and there is a ton of inertia lost in the exhaust. That is why they need so much exhaust flow. Turbos recover lost or wasted inertia in the exhaust, which makes it a match made in heaven for a rotary.

@rad Potential. The holder you put the side seals on where did you get that?

Love the content man keep it up Needmore rotary family❤

I tried to tell you that couple of posts back 😢now we can make some power😊

The stock throttle body can provide enough air to achieve 600+ HP on a 2JZ. I don’t think it’s the problem

On angel motorsports channel they had an orange street port 13b some dude built and he had a trick intake setup on it and made 262whp, the video is called "ITB Track Rx7 Screaming To 9000RPMs (2nd Highest HP N/A Dyno Record)" if you want to check it out.