Are you putting the rotary engine in the truck?
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| New member, swapping slant six into a 2004 Mazda RX8 https://www.slantsix.org/forum/viewtopic.php?t=66262 |
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| Author: | MazdaRX8/6 [ Thu Oct 28, 2021 8:23 pm ] |
| Post subject: | New member, swapping slant six into a 2004 Mazda RX8 |
Hi, this is my first post as a member. I am swapping a slant six from a 1985 Dodge pickup into a 2004 Mazda RX8. I got my inspiration from Uncle Tony with his Miata swap. I am 60 years old with a lifetime of wrenching, welding, and tinkering. I have plenty of tools, a drive-on lift, welder, torch, milling machine, etc. My goal is to make a reliable every day driver to take to the local car shows to meet people and have fun. I am coming out of a divorce after 31 years of marriage and I need something to occupy me. My adult son has recently bought an old Corvette and this will be something we can have in common. My goals are these in this order: 1) Reliable. Must be able to take on trips without concern of breakdown. 2) Smooth and quiet. I am planning on keeping the RX8 exhaust and installing a cutout right behind the engine in case I need to let it talk. I will be keeping the hydraulic lifters 3) Reasonbly fuel efficient 4) Higher than average revving for a slant 5) I want the swap to look like it came from the factory. I plan on painting the engine red. And I want to see people's reaction when the see it. If I can get 200-230 HP I will be happy. The car weighs 3,000 lb. The rotary was 232 HP at 8500 rpm and around 158 lb-ft of torque. I also plan on keeping most, if not all of the engine electronics. The rotary and slant are similar in output. I want to keep the drive by wire, throttle body, oil pressure and water temp, crank position sensor, etc. It seems the older RX8 ECU's lend themselves to tuning. I plan to change the 6 speed OD trans to a 5 speed OD trans because (1) I won't need 6 speeds, and (2) The 5 speed has a .71 OD vs a .80 on the 6 speed. I also read that the 5 speed is a little stronger. I will also install a numerically lower rear end gear to reduce RPM. I have a local friend who modifies Miatas and he has a local friend who is a genius with EFI and ignitions. I will have a custom intake made. I am keeping the cast iron exhaust for noise reduction and accessory clearance. I am using the Mazda alternator and moving it to the driver's side with the AC compressor and maybe a PS pump. I plan on using v belts for simplicity and to have two belts on the water pump for safety. I will make all of the mods to the car then send the engine away to have the head ported, install slightly larger valves, and be built. I do not feel comfortable building an engine. I am wide open to learn from you guys. I have read several hundred engine posts, a hundred EFI posts, bought Doug's book, and just attended the Slanted Nationals in Missouri. I think I have the basic knowledge, now I need help with the specifics. |
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| Author: | Dart270 [ Fri Oct 29, 2021 3:03 am ] |
| Post subject: | Re: New member, swapping slant six into a 2004 Mazda RX8 |
Sounds like a great project. Welcome! Best to ask questions as they come about the design, engine buildup, etc. It appears you have a great set of resources at your disposal too. You can achieve what you want, but it will take some work to make it reliable. You probably have thought of this, but I assume your place of residence has lenient emissions laws? Your project would be sticky in many places in the US. The 1985 engine is nice because it is about 35 lbs lighter than earlier versions so will be good for that chassis. Your HP goal is quite realistic, assuming you have larger valves in the head and some decent porting. I would shoot for around 9.5:1 static compression for this kind of buildup, but there are many ways to skin the cat... Best wishes for your project and we look forward to having you on this site. Lou |
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| Author: | MazdaRX8/6 [ Fri Oct 29, 2021 4:30 am ] |
| Post subject: | Re: New member, swapping slant six into a 2004 Mazda RX8 |
Thanks for the reply. I am in Tennessee and they just did away with the last few counties emissions testing. However, I plan on leaving the cat intact and I hope with the electronic engine controls and a mild build that the car might pass the 2004 standards. They only did a railpipe check here. I had purposely searched for the 1985 engine becausecI had read on the forum here that was the lightest year. I wanted the lighter crank to help it rev quickly. I plan on using the RX8 flywheel and clutch. |
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| Author: | Exner Geek [ Fri Oct 29, 2021 6:55 am ] |
| Post subject: | Re: New member, swapping slant six into a 2004 Mazda RX8 |
I seem to remember another board member who was going to try to swap a Mazda Rotary for a slant 6. I don't remember if he every finished it, but you might find some information by searching for Mazda, rotary, or RX-7. Maybe someone else remembers the same thing and the member's name. |
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| Author: | Greg Ondayko [ Fri Oct 29, 2021 7:57 am ] |
| Post subject: | Re: New member, swapping slant six into a 2004 Mazda RX8 |
Good Luck with the project. When you get the project done you are invited to AutoX and Corner carve with a small contingent of us in the VA / PA /KY /NC areas! I believe I spoke to you at sikeston Mo Dragstrip when UTG was there. Welcome aboard mate! Greg |
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| Author: | ProCycle [ Fri Oct 29, 2021 7:58 am ] |
| Post subject: | Re: New member, swapping slant six into a 2004 Mazda RX8 |
I love these Frankenstein builds. Post pictures! |
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| Author: | Badvert65 [ Fri Oct 29, 2021 8:53 am ] |
| Post subject: | Re: New member, swapping slant six into a 2004 Mazda RX8 |
Welcome to the site. Looks like you are jumping into the deep end with this project, and a manual transmission to boot. Awesome. |
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| Author: | MazdaRX8/6 [ Fri Oct 29, 2021 3:37 pm ] |
| Post subject: | Re: New member, swapping slant six into a 2004 Mazda RX8 |
Hi Greg. Indeed I admired your very fine-and very fast car at Sikeston. I was there with my son and his two friends. They had a great time with old school speed. |
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| Author: | Joshie225 [ Fri Oct 29, 2021 4:01 pm ] |
| Post subject: | Re: New member, swapping slant six into a 2004 Mazda RX8 |
Welcome! Several questions come up for me so I'll just throw them out. How's the engine bay length? Does the truck oil pan fit? Will the hood close? Is the bellhousing to engine adapter something you can design and build? The RX8 flywheel is counter-weighted, has a tapered bore and is held on with one nut. What's the plan for adapting that? The rotary engine has the same firing intervals as a 4 cylinder. How are you going to get the Mazda ECU to provide 50% more correctly timed ignition and fuel injector outputs? |
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| Author: | MazdaRX8/6 [ Fri Oct 29, 2021 5:37 pm ] |
| Post subject: | Re: New member, swapping slant six into a 2004 Mazda RX8 |
Hi Greg. Indeed I admired your very fine-and very fast car at Sikeston. I was there with my son and his two friends. They had a great time with old school speed. |
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| Author: | MazdaRX8/6 [ Fri Oct 29, 2021 8:54 pm ] |
| Post subject: | Re: New member, swapping slant six into a 2004 Mazda RX8 |
Quote: Welcome! Several questions come up for me so I'll just throw them out. How's the engine bay length? Does the truck oil pan fit? Will the hood close? Is the bellhousing to engine adapter something you can design and build? The RX8 flywheel is counter-weighted, has a tapered bore and is held on with one nut. What's the plan for adapting that? The rotary engine has the same firing intervals as a 4 cylinder. How are you going to get the Mazda ECU to provide 50% more correctly timed ignition and fuel injector outputs?
Good questions. The slant is 29" from rear to front of two groove pulley. About 10" longer than the rotary. But, the battery and air cleaner box are between the engine and radiator core support. The swap community regularly swaps the Toyota 2JZ into the RX8, and that engine is 2" longer than the slant because of the timing belt. The best I can figure, the rear sump truck oil pan will fit just fine. There are several companies out there making engine to transmission adspters for popular swaps. Obviously the slant is not one. I contacted one of the adapter companies and they said they would be glad to make me a custom adapter. I bought a used aluminum bell housing and I plan to send it and my flex plate for them to use to make the adapter. They can put it in a CNC mill and locate the holes. I will tell them how thick to make the adapter, and they will make a hub to adapt the Mazda flywheel if possible. If not, I can have a 10" clutch flywheel turned down to the Mazda dimensions, using the Mazda the ring gear. The Mazda clutch is almost the dame exact diameter as the 9 1/4 slant clutch. The Mazda starter comes in from behind, so the slant starter will be deleted. I am pretty sure the Mazda stock flywheel is steel. The clutch, flywheel, and adapter are the least of my worries. As far as the engine electronics go, yes the 2 rotor engine sparks like a 4 cylinder. But I can use the slant distributor. I have already installed an HEI on the truck engine. I might gave to let the Mazda computer manage fuel only until I find a work around. I hope to find some help here with EFI and the ECU. |
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| Author: | plymouthcranbrook [ Sat Oct 30, 2021 8:21 pm ] |
| Post subject: | Re: New member, swapping slant six into a 2004 Mazda RX8 |
Sounds like a fun project. I would suggest being sure to plan on modifying the front suspension as I am sure the 6 is much heavier that the rotary. Not like putting an 8 in but enough to cause some understeer if not compensated for. |
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| Author: | MazdaRX8/6 [ Sat Oct 30, 2021 8:40 pm ] |
| Post subject: | Re: New member, swapping slant six into a 2004 Mazda RX8 |
Quote: Sounds like a fun project. I would suggest being sure to plan on modifying the front suspension as I am sure the 6 is much heavier that the rotary. Not like putting an 8 in but enough to cause some understeer if not compensated for.
I am sure the slant is heavier, not sure how much yet. I'm going to weigh both engines. The slant also will be about 12 inches forward. But, I am moving the battery to the trunk, which will transfer some weight, and I am removing two oil coolers and related parts that are way up front.
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| Author: | emsvitil [ Sat Oct 30, 2021 10:57 pm ] |
| Post subject: | Re: New member, swapping slant six into a 2004 Mazda RX8 |
Are you putting the rotary engine in the truck?
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| Author: | MazdaRX8/6 [ Sun Oct 31, 2021 7:02 am ] |
| Post subject: | Re: New member, swapping slant six into a 2004 Mazda RX8 |
Quote: Are you putting the rotary engine in the truck?
Believe it or not, the rotary is made of cast iron and it has a fair amount of weight. I have not weighed it yet, but the internet says the rotary weighs 375#. I think my 1985 engine weighs 450. But the battery weighs 40# and it is going to the trunk. I don't think weight will be a problem. My car has heavier springs as *part of the package. Lots of people are swapping Toyota 2JZ's with a similar weight. I hope to look to those guys to figure out the electronics.
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