My 2 cents is that a log style manifold (especially a cast one like the greddy) simply holds more heat and keeps it right up against the engine. Though it might be a necessity because of the limited space down there, especially with a low mount location.

A top mount turbo frees you from turbo sizing constraints and IMO a tubular manifold is better than a log.

FWIW, I noticed Racing Beat is now selling exhaust flanges that look to be the same ones they use on their header. Could be used to fab up a tubular manifold comparatively easily.

(Disclaimer: What I know is what I've read, and I haven't read a lot, so please, RG, MM etc., hop in and let me know if I'm right or wrong... we can see how much I've learned! )

 

Just a glance at the 'tortured' shape of the Greddy manifold shows the compromises that were made to fit it there.

S

 

I have something to say about all this negative manifold discussion. I have been doing bolt up turbochargers for around 10 years exclusivly for the RX7. People said for years and years, stock twins are garbage, go single. Our FD turbos made 426 RWHP with reliability. They pass visual and smog testing with flying colors. Same thing about FC turbos. 400RWHP out of a T2 turbo? was that a joke?? NOPE! 412 RWHP and averaged over 400 RW from 6-8K RPM. Old HKS cast short runner exhaust manifolds, I have 2 cars FD and FB. One made 435 RWHP on the restrictive racing beat cat back and the other made 440 RWHP.

All that Greddy turbo needs is altercations to be made right.

Bryan@BNR

 

^see listen to this man!

Good stuff Bryan.

 

All of you are missing the point of why this tangent was set upon. Practically no one here is running the GReddy kit as it was designed by GReddy. This tangent was started because GReddy released a horribly designed product that the end user needs to fix before they can run it. I paid 3k for my kit brand new four years ago and every single thing that was wrong with the kit then, is still wrong with it now, they fixed nothing. So not only did they make a shitty product but they are happy making a shitty product. The quote in RG signature sums it up perfectly:

"Why is there never enough time and money to do it right the first time but always enough to do it again?"

I wasted over $10,000 on the GReddy kit, that includes the $4,200 I had to pay to rebuild my motor. That 10 grand could have gotten me a pretty sweet set up. I've learned from my mistakes and I'm not doing them again. Just read my build thread, it sheds a lot of light on this subject.

 

In my opinion, when a big company like Greddy or HKS designs a bolt on turbo kit with a preprogrammed ECU, they have to be conservative. If they are not, and a large percentage are failing, it gives the kit a bad wrap. Small turbo and low boost levels make it more reliable most of the time, but a lot of people crave more than what the kit can put out so they up the boost and the engine fails. Plug and play is what most customers are all about. But if you go beyond the greddy perameters, you will have more of a chance blowing an engine b/c of bad tuning software.

The life of a turbocharged rotary relies 100% on its tune. If it is tuned perfect, it will have a long life. If it is tuned on the edge, your performance will be best but longevity will be effected. If it is tuned poorly, you may be pulling the engine every weekend until you get the tuning issue solved. You can have all the best go fast goodies on your car, but if your tuning is off, mods are pointless...

 

<threadjack>

You miss the point yet again.

Proper tuning is essential, yes, nobody ever said it wasn't. The Greddy turbo kit, from the box, is so plagued with issues even when run *exactly* as Greddy intended it, that it might as well be a paperweight.

Off the top of my head,

• Manifold is prone to cracking
• Lacks a BoV, frequent surges
• Turbo gets flooded with oil unless a restrictor is used

The greddy kit, as it comes from greddy, is poorly thought out and engineered. I have ridden in quite a few RX-8s with *UPGRADED* greddy kits that were perfectly fine, but the additional fixes and band-aids are ridiculous.

If you need more proof as to Greddy not putting enough work and R&D into the kit, consider that the original maps included with the kit were garbage and eventually wound up being replaced with maps identical to MazdaManiac's (I believe they WERE his maps, correct me if I'm wrong).

</threadjack>

 

/\ which is why this forum is such a great place . You can learn all that stuff before you buy your second hand kit at 50c in the dollar from someone who bought it off ebay and got fed up with it .
You can then set about turning that same pos kit into something really worthwhile for a fraction of the cost of the "good" kits .

 

We are all talking about style points... which is OT in my opinion.

There are two ways to shop... one is by location; IE the best compressor that can fit in XYZ location.

The other is the best compressor period - and then fab it into place.

Most of us have done a lot of piecemeal work; and as such we want to re-use what we can and fix what is lacking... for the one's who haven't started shopping yet - you have a lot more options for your build and can make a really nice set-up if you take your time.

I for one am a location guy - because I want my car to be low profile unde rthe hood - and I know I'll lose some power because of it - but I am cool with that.

 

I see what you are saying. Bypass valves and restrictors aren't too hard to get ahold of. The cracking is an issue. Does it totally kill the manifold or is it hairline?

 

/\ just on the cracking issue ....
Mine cracked and i took to 3 diferent places . They all tried to weld it up and failed - the crack just grew each time . Given that i had had it ceramic coated and each time we had to take more and more of the coating off , I was getting concerned.
Then we tried just brazing it . Max operating temp on the packet was lower than the exhaust temps after the turbo so I thought it might just melt off .
It didn't

 

Aren't tubular manifolds prone to cracking as well? Would a tubular manifold made in place of this cast one be a better option?

 

Yeah, thats the only thing that worries me because I've replaced nearly every single piece of the GReddy setup for my kit, but I'm using a used manifold. *fingers crossed* I'm hoping it doesn't crack because if you can't weld it together, I have no idea how you would go about getting another one short of buying another used kit. So you are currently using your manifold that cracked previously? Where did it crack?

 

I'm going to give Jeff (MM) alot of credit for his work with that atrocity of a turbo system. He's found out what needs to be addressed and then told everyone how to address it. Before the accessport came out he did lots of research on the emanage and told people how to completely rewire it and tune it which is sad considering the company that made it didn't know how to hook it up properly! Greddy did absolutely nothing right with that kit. It's not even because it's conservatively done. It isn't. It's plain and simply poorly done.

They literally took a few parts they had lying around, threw them together into a kit, and put a price tag on it knowing that people would buy it because of the name brand. It worked. Lots of people bought them. Lots of people had failures too. I don't know of a single person who has used that kit who hasn't had at least some major issue at some point. It is in fact that bad! I don't bash the Greddy kit because I'm a turbo hater. I'm not. I like them. Granted I still feel that Hymee has the best option for FI on the Renesis. I have come to hate Greddy for a number of things over the years but this was the last straw. There was no excuse for this kit being done the way it was. They completely shot themselves in the foot with it and then wouldn't fix it. Their customer service is non existant too. In short, they've outlived their usefullness. If Greddy was a horse I'd have taken them out into a field and shot them by now. Off to the glue factory.

 

http://www.aptuning.net/Garrett_T04S...ing%2060-1.htm

You want something like that.

For some reason after about 10 minutes of searching I can't find a ball bearing T04S with a bigger undivided hotside than .70 , which is weird. I ran a .96 undivided but mine was journal bearing and oil cooled.

 

Mazsport even had better customer service than GReddy does....which is not saying much
oops...did I just type that? my bad.

 

Yes i'm using it and brazing worked for me . It cracked just above the lower rear most bolt .
Some members here have suggested you don't need the little support bracket on the down pipe . I think you should definately fit it because it should help to minimise potential cracking issues .

 

Any word on that Garrett OE ball bearing center housing? Cant be that knock off china stuff! It has been almost 3 weeks and I haven't heard from ya...

Bryan@BNR

 

^that seems to be the trend with him, if you haven't noticed from his AP calibrations thread

 

getting banned does not help .....

 

Bryan,

Quickly getting back to the subject of turbo manifolds, you have to remember that a Greddy manifold is not a Mazda manifold. For all the problems with OEM stuff, they still tend to last longer than aftermarket, especially poorly designed aftermarket. It seems these Greddy Rx-8 manifolds are lasting what, 20-30k? And an FD turbo manifold (not talking about the turbo assembly that bolts to it) is good for 2 or 3 times that life, with the FC turbo manifold usually good for 100k+ .

 

where are you getting your information on the greddy manifolds lasting 20-30K?
I'm not being a jackass, I would really like to know. Thx.

 

i was under the impression that those people who had experienced cracking had it occur in that range. But I can't vouch for that exact number and some other people can speak up to clarify. I know lots of people have had their turbos fail in a mileage range similar to that.

The point was not that Greddy manifolds last a specific amount of miles, but that they are not OEM grade in terms of durability. That must be kept in mind when comparing them to stock FC and FD manifolds.

 

^I see what your saying about the longevity of aftermarket vs. the oem manifolds...but I guess I really hadn't heard too much about the manifolds cracking, maybe a few instances.

As far as the greddy turbo, you are lucky if you get 15K out of it. That's about where mine started to fail.

 

What happened? Actually PM me to keep this thread on topic