Hi,

I just bought a pair of stock twins cheap. I was wondering how I could check if they were in good condition. What should I look out for?

My observations so far are:

1. I meant slight crack on one of the inlet ports/manifold.
2. blades spin round but don't know how freely they should be.
3. theye is a very slight play when i push the centre hub of either turbo blades. is this normal?



I am hoping they are, or at least i can weld the crack because i want to have a go at polishing/flowing them . Any comments on modifying stock twis are also welcome.

Thanks guys.
rx7club.com is great!

Trevor Lam

 

Your findings seem to indicate that the Turbos are in decent shape. Assuming the Turbo Assembly/ Housings have not been cleaned, If they demonstrate very little, or no oil residue down the intake opening of the housing (snail) , then that would also indicate that they are in good mechanical shape.

Although, if you find slight (emphasis on slight) oily residue,.. this is normal and should be expected especially if the Turbos have more than 60K miles.

 

Some end and thrust play is to be expected, esp with used turbos. You may want to remove the rotating assys from the turbine housing (10mm bolts) to inspect the turbines and make sure they have no apex seal damage.

 

Thanks very much guys.

Great, sounds good so far.

Now onto modification....

I guess so far I can remove the rotating assy as mentioned above. What else can I safely take apart?

Would it actually make any difference if I get in and polish all surfaces I can reach in the 'snail' as well as the manif. I am hoping I can disassemble it and get to the hard to reach parts, but don't want to take it apart and spoil the turbo.

Trev

 

Don't bother. Not even close to being worth the effort.

 

i did a bit of "polishing" on the last set i took apart.... didnt notice a difference. if they are apart however you may want to conider porting the wastegate if yo uare going to be doing some more power mods down the line that would increase flow to the engine (intake, cat, etc). anyway, if you dont have to dont open them up... i think you should be able to visually inspect all 4 wheels (you just have to peak in exhaust side... well i think you can do this... i usually am looking at them disassembled rather than assembled).

anyway, if you do decide to take them apart here are a few warnings: soak the bolts for a couple days prior with a good amount of PB blaster, or (i like this valvoline stuff that smells like vanilla... i cant remember the name)... anyway, you WILL beak bolts and strip heads (especially those 10MM ones) if you just go at it how it is. secondly, make sure to mark the orientation of both the rotating assemblys BEFORE dissassembly. i didnt do this my first time out, and i ended up having to take the turbos in and out of the car like 4 times and adjust the various rotarions every time in order to get them to line back up.... lesson learned. thats pretty much all i can think of, short or rebuilding them. good luck, -heath

 

the valvoline vanilla stuff is a synthetic lubricant/penetrating spray that works pretty well.

 

thanks goodfella... yeah that was the one i was thinking of. for the twins, i highly recomend this stuff... ive tried many things to free those bolts and nothing beats this.

 

Yup. Smells great.....I can remember tearing up my left hand pretty badly trying to get the oil press reg off of a rear iron when it came loose very suddenly and ripping my hand open on the coolant passages. Blood streaming down my hands, but damn did they smell good

 

Not to hijack the thread but... This question is similar to the first and so I thought it might be relevant and useful here.

Rich, your BNR's are the earlier version (as opposed to the newest) correct? I believe I have the same set here, that are about a year old. Overall condition seems good, but I notice that there is radial shaft movement (but not necessarily play) AND they also seem to be a bit tight. There is no axial (end play) movement.

My question to you is what the normal condition of the BNR's should be. (I assume that this has dynamic seals--so the characteristics may be different than stock.) Anyway, I'm asking you as an experienced and impartial user of the product.

My own turbo experience goes back about 25 or so years when a few of us began to retrofit helo turbos to automotive applications. At the time I noticed that if shaft was tight, the turbine could stop while idling, allowing the seal to weep oil with the accompanying smoke, etc.. So how tight is too tight?