FubarI33t

About to start a V6 swap. Some may hate my engine choice, but hell I already own the engine. I am also not planing to boost at this point. So engine choice is a Audi 2.8 30V V6, Iron block(yuck) alloy heads(5 valves per cylinder) 90 degree V. Yes it's wide. Wiki says it's only 190HP/210TQ, but those who have dyno'ed there cars it actually comes in around 210HP(crank). This adapted to the stock RX8 exhaust(flows allot better then audi stock, and keeps swap cost a bit lower), new intake plumbing, and standalone(spitronics from south. africa) will net more then stock HP/TQ. This stock power will already be pushing the limits of the RX8 Trans. Speaking of it's a 04 RX8 GT Auto(4 port 4 speed). So main questions are: those who kept the rx* ECU, what did you do to keep this functional? I assume you may have used RX8 sensors on the new engine.

BigBadChris

iTrader: (4)

Good luck!

As I understand it, in these swaps you basically have two ECUs. A standalone controlling the engine, and the Mazda one controls everything else: locks, AC, radio, check engine lights. You will have to flash the Mazda ECU to not throw codes, using Cobb or MazdaEdit.

FubarI33t

Thanks. Yup I already assumed the Cobb tuner, and since my 4 port(remanned in 07) still has compression it will be a decent rebuild donor that I'll sale to help offset a fraction of the swap cost. Luckily, the radiator will work, I'll adapt and keep the oem trans, and exhaust. And the engine should still fit behind the cross member thus oem electric ps gets to stay. Those alone help bring down swap cost. And since I can fab up(got a full machine shop at work) the adapters and mounts, swap costs are even lower. Paid 1800$ for a near perfect rx8( low compression) and already owned the 30k mile Audi engine. Costs are a bit lower. We'll see how it goes.

BigBadChris

iTrader: (4)

I am curious to see how the automatic transmission computer will react. It's shift points are based on the unique power band and rev limits of the four port renesis engine. Most swaps I have seen are manual trans. Have you considered that?

FubarI33t

Yes, to a point. For cooling do to extra tq, I will install a good cooler. Rev limits are close to the same. And from what I gather, windows software tuning for Cobb, and I can change some things in trans. Correct me if I'm wrong though. I can/will also adapt any and all sensors/pickups needed for proper ecu/tcu functions.

BigBadChris

iTrader: (4)

It was my understanding that the TCM is independent of the ECU. Several 4AT owners have had their transmissions rebuilt, but they were disappointed to find that the shift limitations were the same. A rebuilt trans can handle a higher rpm, but the TCM would lock out shifts beyond 7500. This was on a supercharged car with an ECU flash to raise the engine redline.

FubarI33t

I do see what your saying. For now I'll probably leave it alone. But Spitronics has a matching TCU for that ECU, they also talk to each other similar to a OEM setup. So if push comes to shove, a standalone TCU won't be an issue.

FubarI33t

Some pics of some 2.8 30V engines. Not mine but same engine. 6 bolt mains the Izuzu engine lighter, But I already own this 30K mile motor.

Prescription 8

iTrader: (2)

The VR6 looked just as strong, 7 mains in that sucker. I just got in over my head with their trans crap.

If you run into problems with the rx trans I recall seeing build threads where people have taken the quattro trans and modified part of it to work only as a RWD setup. I'm certain that trans fits your engine.

Boy does that look wide! I'm curious to see how it'll sit in the engine bay.

Good luck with your build. I wish I could shed more light on the ECU and keeping things functional, but that's far from my goal with my RX-8...

FubarI33t

I've been getting good info from other swappers Via PM, and will soon begin the removal of the rotary. then it's test fitting of the V6, that's when the pics will start hitting this thread.

9krpmrx8

iTrader: (46)

Artsvetkov

Wow that's a tough project, I'm doing 4 cyl swap and it is fairly challenging.

FubarI33t

I thought of a 4 cylinder swap. Torn between sr20 and QR25. Qr25, was good choice due to sweet torque and loves boost. Loved it in my spec v. But I had this V6 sitting out back, and it does have some smidge of aftermarket from it's other version the 2.7TT.

Artsvetkov

Boosted v6 has a sweet power curve, I love my boosted KLZE, but DOHC V6 will be a very tight package in there, I wish you best of luck and ability to tackle problems as they come!

FubarI33t

Boosted may be in future plans, but not at this moment. I've seen the 1UZFE mounted in the RX8 chassis. I don't see why I can not shoehorn this in. Also the B5.5 chassis this engine came out of had a narrower tower spread then the RX8. May have to trim the lip up around the rails. Good thing is good clearance, the engine is not as tall as the 13b MSP with its intake fitted. As well as a shallow oil pan. Oil filter will have clearance issues, it sticks out the front like a wort, but this can be relocated and it's coolant style oil cooler deleted.

lsrx8

5vz-fe?

Spirograph

Interesting project. What's your estimation on how much this will shift the nearly perfect 50/50 weight distribution with the Renesis?

FubarI33t

Lsrx- Not a bad choice, but if I were to choose another engine for this project then what I already have, it would probably be a J-Series V6.

Spiro- Don't know to much, this engine should sit down where the Renesis sits, and crank pulley flush with that cross-member like the Renesis. Weight will be more. But total weight is unknown at this point. I do plan on bringing the engine to work one day and tossing it on our crane load test scale(gota wait for boss to be out

kickerfox

The issue I find when using a FWD engine longitudinally is the starter. Most of them mount on the transmission. I believe the J series was this way. Also, keep an eye out for the plumbing on the backs of FWD heads. They wind up in the firewall. Next is the intake manifold. Can it be flipped 180deg or are there accessories or timing belts/chains in the way if you flip it?

Have a look at this if you haven't seen it yet.
http://www.superfastmiatas.com/JV6%20Miata%20Kit.html

FubarI33t

Good thing with these engines (Audi 2.8 pic'ed above), there fwd, but still mounted longitudinal. So everything is as if it's rwd. Including starter, rear coolant tubes etc.... Coolant input/output is in front, as well as heater core connections. Although at the moment I will pull the renesis and teardown, then chose to swap or rebuild biased on condition. A low boosted 4 port is appealing to me.

FubarI33t

Choose another engine. thread done.

BigCajun

iTrader: (1)

What happened? It won't fit?

FubarI33t

it may fit, If i were to play with installed height. but where I wanted it to sit, it was 29" wide. rail to rail was 27". I've since choose another engine that's lighter(lighter then renesis too) and has major potential for output. I hate to say just what engine, but I've started ordering the ECU already and engine comes next month.

9krpmrx8

iTrader: (46)

Well we won't hold our breath.

BigCajun

iTrader: (1)

Props for updating your thread and not just fading into oblivion like a lot of swap threads.

Why don't you want to disclose your choice?