Rx8 supercharging vs supercharging 370Z or gt86

[Kellytm272]

I’ve been thinking of supercharging my 8 for a while, which I’m guessing to do right is going to cost in the region of £10k. But obviously getting hold of a supercharger isn’t easy. Does the performance increase justify the cost? Would it out perform a stock rx7?
Never seem to see anything in terms of stats on the net.
Or is it better to go with something like a gt86 or 370Z and supercharge one of them in the future. Kits for those cars seem easy to get hold of, obviously because they are still current. The Cosworth setup for gt86 looks good.
Whilst the performance of a stock rx8 231 is nice, I miss the sort of raw acceleration that my old mr2 turbo had.

[tayfun]

If I had spare £10k to invest into supercharging rx8 and spare 1 year, I'd go with something like making a 13b-rew swap which would make rx8 more reliable and had more performance potential than any of the cars from your list, but easiest way to get more power is use another car...

Also I heard that gt86 with super(turbo)charger isn't something more reliable than boosted renesis

[Kellytm272]

Interesting and good point with the engine swap. Only seen it mentioned once before, but wasn’t sure it was now possible

[SeriousSam]

It's not about it 'now' being possible, it's just nobody bothers because you've got to invest ten to fifteen grand in a car that's worth a fraction of that. Puts people off somewhat. If my engine chooses to let go at some future point, I'll be going with an FD swap, but there's plenty of other stuff I need to sort before then. This would bring you up to a solid and reliable 300-350 BHP, in a package that's not too far removed from what Mazda were aiming at with the RX-8 in terms of handling and balance.

If power is your aim, then the RX-8 isn't an easy car to hit the numbers with, so your ideas of a 370Z or GT-86 are sound enough. Neither of those engines was built for boost from the factory, so may require further engine mods to support bigger power, but if a modest lift is enough then that's probably the easiest and cheapest way. I'm still tempted by the idea of a 200SX for the same reason - easy modification to release more horsepower.

[tayfun]

Also there is one shop in Russia that sells some parts that you'll require to have for 13b-rew swap and the prices aren't too expensive

https://nicon-rotary.com/en/product-category/rx8_swap/

They do rew swaps themselves too, so can help with everything you need, but most expensive part of this swap is obviously engine with rebuild and then goes turbo, exhaust and ECU (depending of what are your goals, but if you want basic swap you can leave 2 ECUs) and other small fabrications and relocations

That's so far what I heard from other people who done rew-swap in Russia

[GreySilver Beast]

I wouldn't advise a Turbo or Supercharger for a GT86/BRZ unless you are prepared to pay out at least 10k to do it probably and then you might as well buy a car that has this already as most new cars have Turbo's

Mercedes have dropped Superchargers in preference for Turbo's instead on their new cars

[Dr. FrankenRex]

GT86 'charging is a reliability issue. There's a fair few instances where people have just bolted on a cosworth kit and then they blow up in a few months/ miles.

[350matt]

GT86 'charging is a reliability issue. There's a fair few instances where people have just bolted on a cosworth kit and then they blow up in a few months/ miles.

Sorry but that's simply not true

not one Cosworth equipped GT86 has gone pop thats running on the Cosworth tune and setup

the only one that has failed was running a custom setup to greatly increase boost over the stock kit

other people have failed big-end shells due to oil starvation but thats down to sticky tyres and a poor sump design and happens with any of these

the standard bottom end on these engines is good for about 105 Bar of cylinder pressure and the Cosworth charger kit is set to achieve 100bar

this kit was then tested on the dyno for 600hours including a 50 hour Wide open throttle test
at the end it was stripped, crack tested and all parts measured - all was within limits and no cracks.

the dev car was also driven 20K + miles to calibrate and check the kit and was still going strong when we later sold the car

how do i know? Well I was was the one who did all this work.

other charger / turbo kits are available and yes folks do go bang with these but often you'll find they have been a bit keen with the boost and chasing 300whp figures etc etc

if you want this sort of figure then you need some steel rods

[Dr. FrankenRex]

Fair play, apologies for repeating what I'd heard on the internet!

[Ryan Rotary Performance]

I’ve been thinking of supercharging my 8 for a while, which I’m guessing to do right is going to cost in the region of £10k. But obviously getting hold of a supercharger isn’t easy. Does the performance increase justify the cost? Would it out perform a stock rx7?
Never seem to see anything in terms of stats on the net.
Or is it better to go with something like a gt86 or 370Z and supercharge one of them in the future. Kits for those cars seem easy to get hold of, obviously because they are still current. The Cosworth setup for gt86 looks good.
Whilst the performance of a stock rx8 231 is nice, I miss the sort of raw acceleration that my old mr2 turbo had.

If you're serious I'll make you a kit!

[Eddie_r32]

Fair play, apologies for repeating what I'd heard on the internet!

I think it's the hks or greddy kits that keep going pop, cosworth makes a good kit

[GreySilver Beast]

I don't know of one Cosworth Kit that has gone bang since it was released

[Kellytm272]

From what I could see on the gt86, the cossie kit was the best one. Think it was good for 280 Bhopal before the con rods need replacing or there abouts.

As for the 8, I’ve put a lot of time and money into it and if there’s a way to get decent power with reasonable reliability then I’m up for it - probably with a £10k upper limit (ish). Although that’s likely a month or two away.

I think after looking at the racing beat site, there were a fair few other mods required before supercharging or turbocharging the Renesis. Can’t remember what mind you, no doubt cooling etc.

If I can get something similar to the old 90s jap sport car performance out of the 8, by supercharging, engine swap...then that would be my preference though

[njkmr]

I have been looking on YouTube of late at some of the engine swaps done on an RX8 and LS1 conversions seem fairly popular in the states. I think its a Corvette engine and obviously they are putting out mega bhp with reliability.
Does get the mind thinking...! what if, if only..!

[tayfun]

I think that engine choice depends on what fast cars are produced/popular in your country, for example in our country people always choose some old beemers engines to swap anywhere, in russia they choose 2JZ/3UZ or the most stupidest engine swap - from Lada https://en.wikipedia.org/wiki/Lada_110#Lada_111

the cost for those swaps are something near 2-3 grands and after you get a car that accelerates fast, but lacks any handling on corners...

In US you can even buy some sort of full LS-swap kit for rx8, but getting LS itself will be an expensive part

[Kellytm272]

You’d imagine that a corvette engine would upset the cars balance - although I guess that’s not of paramount importance if shoving one of those in. Can only imagine it’s more for the drag strip or straight line speed.
I imagine that an rew swap or supercharger/ turbo on an rx8 wouldn’t mess the balance up too much

[njkmr]

Theres a reconditioned one on ebay now for £2850. From a reputable dealer.
410 bhp at your disposal in standard trim....
Ummmmm.....

[New Duke]

I’ve been thinking of supercharging my 8 for a while, which I’m guessing to do right is going to cost in the region of £10k. But obviously getting hold of a supercharger isn’t easy. Does the performance increase justify the cost? Would it out perform a stock rx7?
Never seem to see anything in terms of stats on the net.
Or is it better to go with something like a gt86 or 370Z and supercharge one of them in the future. Kits for those cars seem easy to get hold of, obviously because they are still current. The Cosworth setup for gt86 looks good.
Whilst the performance of a stock rx8 231 is nice, I miss the sort of raw acceleration that my old mr2 turbo had.

If you're serious I'll make you a kit!

I've started saving my work bonuses into a SC fund Carl. In the hope of getting you to do one for the R3 in the future.

Sticking a big lump under the bonnet just seems to undermine the main benefit of the RX8. If you want a faster car in a straight line that handles worse... that's pretty much every other sports/executive car!

[njkmr]

So in a nutshell ,what can a Supercharger offer in terms of bhp , reliably (so no silly pub talk numbers) and what is a ball park figure to have it done in the RX8?
All in fitted tuned ready to go.
I love my RX8 to be honest and it makes me smile every time I see it but oh for some extra oomph..!

[Kellytm272]

One thing I wondered, and I know that you don’t buy a rotary for this, but...fuel economy. How much does it suffer?! Can’t say I’ve looked into it, but I imagine that adding a supercharger to an 8 would have a dramatic effect on fuel economy. In this sense, would the rew conversion be better in terms of everything? Except possibly financial outlay, although I don’t see any options costing less than £10k all in...

[350matt]

I'd say a genuine 300+ bhp at the e shaft / crank should be doable on about 0.5bar of boost, and with a positive displacement blower you'll get an uplift from low speed too

as for the cost then it's well worth following Pensive's thread in the boost junkie bit of the site as he's trying to do it for about 3K in parts + mazda edit mapping
this is hard to do but not impossible
the biggest challenge is fitting it all in as the rexi bay is quite tight
I'm putting pieces together to have a go at a conversion myself but funds are tight , so I'm watching Mr pensive's efforts with interest

[warpc0il]

Tony [exiledviking] has a supercharged 8 and probably gets better fuel economy than any of the rest of us.

He's also your best source to determine how much it cost to create and run a SC 8, in the real world.

[350matt]

One thing I wondered, and I know that you don’t buy a rotary for this, but...fuel economy. How much does it suffer?! Can’t say I’ve looked into it, but I imagine that adding a supercharger to an 8 would have a dramatic effect on fuel economy. In this sense, would the rew conversion be better in terms of everything? Except possibly financial outlay, although I don’t see any options costing less than £10k all in...

you might be surprised, on the gt 86 kit fuel consumption dropped by about 10% in normal use. obviously its a lot worse if you're always on the gas


most modern blowers have a re circulation valve so the blower is unloaded when you're off throttle so the parasitic losses are greatly reduced when you're just tootling round town

[Kellytm272]

Ah okay, that’s pretty cool. I always thought of them as pretty much always on. Makes sense to do it the way you described :-)

[Ryan Rotary Performance]

If this is something that you guys want and are committed to I will restart my supercharger project.

I estimated £6K for a billet machined solution with a charge cooler, powered by a 2.L screw type blower.

The Pettit system was only a 1.7L and that can give over 300hp