frankenstein'ing my stock twins...
 

so i just picked up a 2nd set of used twins.

on my existing set, the rear turbo went bad and spits lots of oil/doesnt boost properly. the front turbo, however, boosts like a mad mofo and doesnt seem to leak any oil.

on the set i just picked up, the rear turbo was recently rebuilt by mazda under warranty, and the front turbo has some shaft play but seems to be OK.

now, would it be a good idea to take the rear turbo off of the news set, and put it on my existing set with the good front turbo?

i'm just looking for a temporary solution while i decided on if i want to go single or bnr stage 3.

32 views and nobody has any input?

I would just run the newer ones as is first. No sense in going through the motions of mix and matching the turbos unless you have to. ;)

Only thing I see if blancing and clearances.. I would say don't try it, save your time for something else.. Either go new 99s, BNR stage 3's or a single.

well i guess i can at least port the wastegate before i put the 2nd set on.

yes, you can combine the two and they will work perfectly fine. just make sure you're careful when removing the chra from the turbine housing.

Rebuilt by mazda? I thought mazda only sold the assembly. Not to mention rebuilding the stock twins is tedious at best... not something I'd trust a mazda mechanic to do.

As far as mixing and matching, I have some experience... alignment can be an issue unless you use certain methods like bolting the turbos to the manifold and then tightening them to the center (downpipe) housing. There is enough play in those holes to have the turbos at an angle relative to eachother, causing one not to seal against the manifold.

I'm not sure why you want to take the rebuilt set apart, unless you think you can do this while they're still in the car, which is impossible at best
I would just swap out the bad set for the good set
I also have experience with mixing and matching and as alexdimen stated, the alignment is the hardest part
Just throw in the rebuilt set and send your set to BNR, you'll be much happier in the end;)

so.....update



had the car up on the lift today to install a new clutch, flywheel, fuel filter, plugs, power fc, m2 airbox & hard pipes, etc.

also took the turbos out. think i found the problem with my existing turbos:

found a missing bolt:
http://tfrascone.net/myphotos/g2data...rbos_whole.jpg

this bolt was missing when i removed the turbo assembly:
http://tfrascone.net/myphotos/g2data...ssing-bolt.jpg

the "new" (60k miles total, rear turbo rebuilt recently) turbos i picked up:
http://tfrascone.net/myphotos/g2data...rbos_whole.jpg

taking the "new" set apart:
http://tfrascone.net/myphotos/g2data...sassembled.jpg

removing the rear turbo assembly:
http://tfrascone.net/myphotos/g2data...compressor.jpg

the recently rebuilt rear-turbo - will put this into my current set:
http://tfrascone.net/myphotos/g2data...or-removed.jpg

we should be finishing the swap tomorrow so i'll post more photos and results. pretty much, i'm going to take "the best" of each set to create one working set.


on a side note, i believe my turbos had some work done to them. notice the odd reddish color on the exhaust side manifolds? it looks like some sort of heat resistant type coating. i think the previous owner may have had turbo problems in the past (and failed to tell me about them). whoever was working on the turbos previously must have not tightened all of the bolts properly - hence once missing...

updates tomorrow...

This missing bolt is a very common problem. I lost like 3 or 4 of them over a period of a year. I ended up safety wiring the bolt head.

another update...

spent most of the day working on the car.

ported the wastegate (wow...45 mins of grinding with a shitty sears rotary grinder tip). now the wastegate port is almost as large as the flapper.

i reassembled the twins after finishing the porting. i ended up using 1/2 the parts from my stock twins, and 1/2 the parts from the "new" set. i'm guessing that my exhaust manifolds had more cracking in certain areas (with only 30k miles on them) because they were ceramic coated.

put the tranny back on the car...2 hours of pure hell. we couldn't get it to slide all the way up to the motor. ended up having to drop the engine 2 inches (lowered the sub frame) and then pulled the tranny to the motor by tightening the bolts from way out.

exhaust back on...removed my high-flow cat downpipe and put a straight through downpipe on.

engine side...removed my intercooler to drain the oil from when the rear turbo went bad...probably 1/4 of a cup in there. also installed the M2 carbon fiber airbox but had some problem using the stock hoses.

all that's left is to connect the intake hoses to the airbox, pop the intercooler back in, add tranny fluid and then bleed the clutch.

FINGERS CROSSED!!! results tomorrow!

:P now that you have a spare set , BNR those puppies ;)

He's just swapping out the turbo cartridges. not taking the turbo's themselves apart.

HELL YES!!!

total success. the car is running 200% better.

i was worried about the turbo assembly...i've never taken the stock twins apart before. also, considering the twins are now the mutation of two separate sets...

there were a few hic-ups along the way, but everything is working great now.

i turned down the manual boost controllers almost all the way and i currently have an 8-5-8 boost pattern. even still, the car pulls so much stronger and i no longer have a strange sounding secondary turbo. i can definitely feel the difference that porting the wastegate made. it helped make the sequential transition much smoother.

i'll post a better update, with pics, later.

ok more info on the previous update.

so it seems the frankenstein twins worked! i used the front turbo & manifold from my existing twins, and combined them with the rear turbo & manifold from the "new" set of twins.

while i had the turbos taken apart. i ported the wastegate. unfortunately i didn't have a carbine bit so it took FOREVER. the results still came out the same. now the primary wastegate port is almost as large as the flapper. i've noticed that i don't spike as bad now.

like i said before i'm currently getting a 8-(5 or 6)-8 boost pattern. that's with my manual boost & pre-spool control valves straight open. i'm going to turn up the boost sometime next week when my power fc comes. (thanks FDNewbie!)

the new clutch is awesome. perfect for a daily driver. grips tight and quick but still very easy for street driving. the sr motorsports flywheel is great too - the car definitely rev's up faster, but i've found that i really have to compensate with the heel-toe when downshifting, otherwise the rpm's drop pretty quick - a small price to pay.

the m2 airbox seems to really help as well. i'm only making 8lbs of boost right now but i swear the car pulls so much harder than before. this could be because my turbos were going bad before...but i'm sure the new additions helped too.

like i said, my Random Technology racing pre-cat was removed and i installed a straight downpipe. i've noticed it's a lot louder, and more rotary-sounding, but i like it. i'm trying to sell the random tech pre-cat, it's in the classifiedes. it only has several hundred miles on it so if you need a pre-cat upgrade make sure to check it out!

well, here's a pic of the engine bay...it's looking pretty empty now that the stock airbox is gone...

https://www.rx7club.com/attachment.p...1&d=1186214245

I wish I had a lift :(

Madslow has a nice polished Greddy stock mount IC for sale that would spruce that engine bay right up and help keep the fresh turbo charged air cool.

lift
 

ART racing in sarasota was nice enough to help him out with that:)

hell yes! if you guys need work done, and you live anywhere on the gulf coast of FL...make sure to go to ART! they kick ass!

I might just have to do something similar! This was a great idea.

Add to it some safety wire in the problem bolts and a ported wastegate and this could very well be an easy turbo fix. Plus, since both turbos are Hitachi HT-12's, then you could technically use the cartridge from either the primary or secondary in either of the positions... correct? Please inform.

yes, i believe i read on another rx7 site that some guy switched a front cartridge to the rear because he had two sets with good front turbos.

That is what I was hoping! Good to know I have 1.5 good sets of turbos.