Building a Twin-Turbo Isuzu V6 for a Mazda RX-8

Mazda RX-8 with a twin-turbo Isuzu 6VD1 V6

A reader contacted us to share their unique project. They are building a 3.2 L 6VD1 V6 from an Isuzu Rodeo to power a Mazda RX-8. They will boost the engine with two Garrett T25 turbochargers from a Nissan 300ZX with a goal of 400-450 horsepower. The engine will be mated to a Pontiac Solstice transmission with an Isuzu Trooper bellhousing, tail-shaft from a 1994 Rodeo transfer case, and Chevy Colorado slave cylinder. The driveshaft is from a 2000 2WD Rodeo with a rear u-joint from a 1990 Dakota and RX-7 driveshaft flange which connects to the RX-8 differential. All told the project will use parts from 15 different vehicles. We will continue to follow the project’s progress and publish updates as we receive them.

Mazda RX-8 with a twin-turbo Isuzu 6VD1 V6

Mazda RX-8 with a twin-turbo Isuzu 6VD1 V6

Mazda RX-8 with a twin-turbo Isuzu 6VD1 V6

Mazda RX-8 with a twin-turbo Isuzu 6VD1 V6

Mazda RX-8 with a twin-turbo Isuzu 6VD1 V6

Mazda RX-8 with a twin-turbo Isuzu 6VD1 V6

3 Comments

  1. Callum

    Hi guys, I’ve done heaps of reading about this and followed the build thread accross a couple forums but the author and forums just went dead and we never heard if it got completed. If there is any chance you may have a way to contact the owner (email will even do) I would love to be able to talk to him and get some info as I will be building the same motor just in a soft vehicle and for a higher power goal. Cheers

    • Charles Brittain

      I don’t know where he went but did you see what one of the Australian Enginemasters sent him? “Hi Jeff, we do have a lot of experience with these engines, with a safe tune up you will have no problems with your engine at 450 flywheel horsepower
      (400 at the wheels) If you have the engine apart to replace the crankshaft I would pull the pistons out and “open” the rings gaps on the first and
      second rings to .005” per Inch or .018”-.020” top ring gap. The stock crankshaft is strong enough for about 700-800 hp (we have run them over 1200hp
      for short bursts). While you have it apart you might also look at the main bearing oil feed, the oil is fed through the Alum cradle that bolts to the
      main caps, the rear main gets the least amount of oil, we modify the feed to come in the centre and feed out from there, we also modify the oil pump
      for more pressure and “port and polish” the oil pump for better flow. All these things are easy while you have the engine apart. We have run stock
      engines to 600hp for short bursts. To make 450hp you need at least a GT3582R running 10 psi boost through an air to air intercooler, the valve springs
      will hold up to 10psi boost at 6500rpm it should make 450hp at 6200rpm. I recommend shimming the oil pump 5mm or 3/16” never had an oil pump failure,
      never seen rod bearing failure, yes drill all main oil feeds, the good thing with turbo engines is you don’t need to rev them hard, like I said earlier
      we have run many of these stock at 450hp and 10psi boost, creep the boost or rpm up and that’s when things get scary. I hope this helps”

      “I have not seen a s.o.h.c 6vd1 however, I have a lot of experience with the dohc version (would be the same bottom end) I have one here at the moment
      running 1680hp, the stock rods fail at around 600hp and the stock pistons fail at around 450hp. I can’t comment on the flow of the heads, because I haven’t
      seen s.o.h.c. but for the twin cam we run larger valves and custom porting, 80mm throttle body and big cams. Even on the mild engine with a gt3582r turbo
      (700hp capacity) we see around 520 rwhp”

      When these motors spin a bearing it’s always #1 and no one knows why. I think the idle oil pressure is around 7psi. eek. Adding two turbos is only going to
      lower that pressure. This other pump might help. The non-vvt non-gdi engines, like mine, use a different pump then the vvt gdi version, like the ’04 Axiom.
      The blocks are the same except for one difference I just noticed. In my ’99 block, the oil feed to the cylinder heads is taken off the #1 main bearing. In
      the front of the engine is a port with a steel ball capping it. In the ’04 block, this plugged passage is open and the oil pump has a hole to feed oil
      directly into that passage. I’d assume they cap the hole off the #1 main. The ’04 pump looks like it may also have a poppet valve to regulate the pressure
      into that hole as well as the main poppet to control pressure to the rest of the engine. I’m sure this is done due to the vvt oil requirement. The rear of
      the pump has a different cover as well which may indicate a change in the gerotor set. If that’s the case, I’ll use the ’04 pump but leave the front of the
      block plugged. If that pump has extra volume, the whole engine gets it. The earlier non-vvt engine doesn’t have any oil issues with the heads so the mod
      would only be for the extra volume the whole engine can benefit from.

  2. Maninder Singh

    Is this project Done please tell me any of your social media page or account where I can get the update on this project

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