RX8 Honda V6 Engine Swap
 

Hello everyone, Just here to give you all a glimpse of my project RX8 until i can post the entire project in the correct topic location.

First things first the car is completed 100% and has been daily driven for the entire summer. I did not want to be another guy that post's his build and never finished.

So the project car is a 2004 RX8 6 speed. Recently swapped to an Acura 3.5L V6 engine!:yelrotflm

This was a project that took over 2 years to build on/off on the weekends when i had time to work on it. 100% of the swap was completed by myself. The project was to challenge myself and not just swap another engine into a car but to engineer the whole project, as well as to demonstrate to everyone that anything can be done regardless of what people think.

Here are a few pics

LOL as to be expected!!!

Props for being different. :icon_tup:

Nice work
 

Though it's not a rotary swap I still give it two thumbs up!

You can't post a swap thread without including all the details. Have some decorum, man!

It looks to be very well executed, if sacreligous. Why'd you choose that engine? How's handling now?

Which J series engine is this exactly?

Thanks for the comments.

It is a J35a3 (orginally started out with the j32a2 260hp)

Power: 248 hp (185 kW) @ 5800 rpm
Torque: 242 lb·ft (328 N·m) @ 4500 rpm
Not sure of power right now haven't dyno'ed it yet

Heads and intake PNP
Type S Cams
80mm Throttle Body
Ebay headers modded for 2inch downpipes to a 3 inch to stock exhaust with electronic cutout.
Chromoly Rx8 flywheel
Spec stage 2 clutch
Tuned with Mega squirt
Stock Rx8 transmission
Stock drive shaft, PPF, Diff

Chose this motor because of Power/Price/Weight/Size

Motor fully dressed with adapter plate and flywheel adapter, engine mounts, and headers weighed in at approx 320lbs. If i remember correctly i weighed the rotary engine at 280lbs.

Engine sits approx 1.5inches closer to the steering rack than the rotary.

Also to mention i bought this car 4yrs back for next to nothing, previous owner wrecked the car blew the gaskets on the rotary. I had fixed it all and driven it for a year as well as tracked it a few times. thought about boosting it and other rotary swaps but ended up doing this.

My goals with the build was to do it as if the car came with this motor. so everything else had to still function properly.

To be honest on the street I don't really notice the difference in handling the car still feels well balanced and controllable. 1st, 2nd is a bit touchy due to wheel spin even with good tires. I have not tracked it yet to really tell. I think the only way to know for sure is to drive a rotary and mine back to back. I believe an experienced driver will be able to note the change in handling. I've done my best during the install to minimize the impact to handling.

Cool deal man. +1 for a well constructed build.

This is something I will look at after my second engine.
Could you share with us more details and pics as:
engine mount
exhaust
transmission adapter plate
Flywheel adapter
What work and what doesn't
etc....
That would be very kind of you
Regards

What did it take to adapt the stock RX-8 transmission to that Honda engine?

An adapter..............

Hahaha, so direct, lol. Of course he used an adapter but he didn't state if he made it or if it was purchased.

Awesome build man! Nice to see a different engine option to swap. Not to mention thats a wicked motor. Interested to see how it drives, post a vid for us!

In tour first post, you wrote :
until i can post the entire project in the correct topic location.

Can you tell us about when you think of doing it ?.......please ?
I realy want to know more about it,
Regards

How has this swap held up over time?
 

How has this swap held up over time?
 

You said you have the flywheel adapter drawn up. Would you be able to email it to me? I know the guys that make the j miata kit. And while it's a nice kit I don't like convertibles. What did you do for an engine computer? Thanks, Mike

Different engine
 

Pretty Awesome, One of the many Non Rotary Swaps in my head is a Mitsubishi V6 paired to the stock RX-8 Transmission.... They make some really good power with basic mods while staying Naturally Aspirated, and are extremely reliable and easy to maintain (Parts can get pricey sometimes) and the Engines themselves can be found for pennies.

I’m very interested in this swap. I’ve thought about this exact thing on and off for several years. I also love that you picked the j35a3, forged internals from the factory, very nice. From what I can see, you didn’t have to remove toooo much of the firewall? I’m hoping you didn’t need to remove the heater core, as you said the car must function as stock. Any extra information you can provide would be GREATLY appreciated. I’m picking up an RX8 this summer, and am trying to plan a possible piston swap for the future. I DO want to keep the rotary, ultimately, but the fuel economy will be a factor. The Honda v6 will be reliable, consume far less fuel, and have much more horsepower, AND torque. Rod bolts and cl type s cams and this should rev to 8k no problem. As long as it fits without having to reposition the steering rack, I really believe this is the best option available, in terms of a piston engine swap. These Honda j series are routinely turbocharged to over 800hp with stock internals. They’re light and strong. This man is onto something.

800 you say, I've always heard the j series tapped out at about 450 with rods being the weak link as usual.

Yeah, I have seen some people turbocharge the V6 Accords and they usually go for 450-ish. But obviously on a FWD car, traction will be a much bigger issue than making power.

J35 is an okay engine, I guess... If(and that's purely theoretical because I would never do it) I have to consider a piston swap, good'ld LS will be it. It makes much more reliable power stock and doesn't really burn much more gas than a J35. J35 also has a timing belt and in a long run, can be a bit of a headache and extra work. And it's SOHC... I can at least see OHV in the LS being compact and have low centre of gravity, but otherwise why not pick something DOHC?

And doesn’t require losing the HVAC chopping out the firewall ...