4CN Air

iTrader: (7)

I've plugged the EGT probe hole with a brass pipe plug, will this melt in it's location shown in the pic?

Also is it alright to have a divided manifold with only one pipe going to the wastegate? The pipe vents gas from both sides, right near the turbo flange. So I guess it wouldn't be fully divided, there would be a little area right before the divided turbo flange where the gasses could mix. Would the benefits still be seen?

The manifold is currently undivided and I've foudn a good deal on a divided 1.15a/r hosuing. Which would be perfect. My turbo is BB so it'll make up a little for the lag, as will the street port, and the manifold is tubular with decent length runners which will help. And if I could have it divided lag would all but go away while the large size would prevent me from choking at high RPM's.

BTW this is a BB 62-1 with a 3" DP with no cats through N1 duals

saxyman990

Melting temperature of pure brass is ~1700deg F. The upper end of exhaust temps for rotaries is quite a bit above that. I would recommend using a Steel npt plug instead of the brass one. You can easily find one at mcmaster

-Rob

4CN Air

iTrader: (7)

yeah, I'll go with a steel one. i can get one at Ace. What about making the manifold divided?

pistonsuk

Depends on how well the air can flow from the main runners to the wg runner. I have a similar setup (racegate, 60-1, full exh, similar manifold) and due to creep the minimum boost I can run is about 12psi at WOT. I think the creep is wg related (42mm) not manifold design though.

I had to once modify a manifold due to too steep of an angle between the main and wg runners after installing a full exh. Just changing this angle alone nearly eliminated creep on that setup. The wg runners should be "Y'd" off of the main runners. In my experince if you have doubts it will not flow enough, then it probably wont.

This is hard to say. I guess the only truley divided manifold would have twin wgs and a separate runner for each.

4CN Air

iTrader: (7)

but yet Even HKS's uber expensive SS piece has one wastegate. I think long wastegate runners in the trick. Seems nothing ever works out for me. I find a good deal on a turbine housing, but it's divided and my manifold is not. So now do I save money on the turbine and put the extra money into modifying the manifold and have it possibly not work as well? Or just buy a more expensive but less efficeint housing?

RacerXtreme7

iTrader: (2)

Your mixing and matching for saving a few dollars is biting you in the ***. If you'd just make a plan and a budget and stick to it instead of constant compromising to save a buck here and there you'd have a set up by now.

It’s a non-divided manifold. Trying to make it fully divided is silly for several reasons. ONE you’re adding to the cost of the manifold, when your done modding it you could of bought a proper manifold from the get go. TWO putting in a divider will SUCK for a couple reasons. You wont be able to weld it fully in because you can't weld but so deep through the little hole on the flange (trying to fit a tig in a tiny hole isn't going to work), even if you cut the flange off, you still wont be able to get it fully welded in. Even if you got parts of it tacked in, it'll eventually fail and it will still leak from one runner to the other. Even after cutting the thing into a ga-zillion pieces to be able to fully weld it up, you still have the crappy waste gate placement were you'll only be bleeding boost off of one runner / rotor {BAD IDEA}. Well, then you'll need to tap in another waste gate runner and merge both of those together to one waste gate or run two waste gates (you already have one, so toss it and buy two tials 38mm, ohh wait.. but you already bought a gate). get the idea here?? It’s a major waste of money and time.

Your wanting quick spool, I've read your post before. Running that manifold with a divided 1.15 A/R turbine with a 62-1 will be a lazy spooler. You want better spool??? Buy the right manifold and right turbine (both divided, long tubular runners and .84 A/R which is still good for well over 400 whp).

Your half ball bearing (yes half, turbonetics only uses thrust ball bearings and there’s still standard sleeve bearings in the CHRA) turbo will speed spool MAYBE 300~800 RPM. So don't use this as a factor when determining turbine trim and A/R.

My advice.... Keep the manifold, keep the wastegate, get a .96 A/R turbine housing (using a divided turbine on a non divided manifold KILLS spool and eventually will crack the turbine housing), bolt the stuff on and be happy. It should still spool and see 10~14 psi before 4000 RPM with a medium to large street port and good tuning on a healthy engine. You want quicker spool, get a .81 A/R turbine and you still will be able to squeeze 400+ whp through it. Want quicker spool yet??? You should have bought a smaller compressor.

Don't concentrate on numbers and being an internet hero, if you'd ever been in a 350+ whp Rx-7 you wouldn’t been shooting for an arbitrary number like 400~450. A 350 hp Rx-7 is FREAKIN FAST and trying to keep your wheels from spinning requires discipline and WIDE STICKY and expensive rear meats.

And YES...... as I’ve said numerous times in many different threads.... ALL T4 P-trim turbines no matter the manufacture most likely will interchange (absolutely YES when going from a Turbonetics to Garrett, Innovative etc etc). Like I've also said, Turbonetics, Innovative and MANY other turbo companies basically sell GARRETT turbo components, or GARRETT component clones along with their own proprietary pieces (including those MASTER POWER and Turbo XS junkers), so every thing so as long as there in the same family and trim will interchange.

Sorry if I come across a little stern, but constantly asking for advice, then totally ignoring the advice given (even when its not mine, but from several people) gets my underwear in a knot.

Good luck with your project and keep us updated.

~Mike.........

4CN Air

iTrader: (7)

I appreciate your thorough post. However I don't understand the tone of it. If I've ignored any advice (which i don't see where I have) it's been due to financial reasons. Of course if I had set a plan and stuck to it I wouldn't be in this situation, but my funds are finite. My PLAN was to swap my new motor in. It turned into a never ending single turbo conversion. The saying goes: Hindsight is 20/20, and it's true. Hell if i would have known how much i was going to put into the car and how much of my life it would take up maybe I would have considered waiting to get it until i was out of college and could devote more time to it. I don't regret getting it though, I've learned a lot along the way. I do all the work myself because money IS an issue. I could have had this done long ago if I had bought new and paid soemone to install it.

No I haven't been in a 350whp rx7, but I have been in a 310 (mine) which I felt could use some more. I saw that 400 CAN BE a relatively "safe" area as far as HP goes. Not requiring drivetrain mods or motor pinning. THAT is why I went for that number. If I were a number junky I could have thrown a huge turbo on there and gotten 500. I have the supporting engine mods, but I wanted streetability.

I'm not exactly sure how I've angered you. Some of the things you say are true but as I've said there are other things you don't see. It's easy to look in from the outside and tell me how I could have done better from the start. I wasn't asking for an analysis of my prior planning, only for help with pursuing my project in the most cost effective way.

No where in my post do I ask "again" what turbines will work, I stated that I had found one I wanted to use. Also I know what the Turbonetics BB system consists of. Although some have questioned it here or more commonl have "heard" someone who once questioned it; I've heard many good things about them, and for the price it was worth trying out.

Finally yes I do ask for a lot of advice, I prefer this to blowing an engine. If you aren't willing to give the advice then ignore my questions. There was a time when you were on the other end . . .

Snook

iTrader: (12)

damn that's a sick *** manifold

leave the brass fitting in there it's fine

RETed

I've got brass NPT plugs (from Home Depot) on my stock exhaust manifold on my FC turbo.
They haven't failed yet.
I regularly see 900C according to my GReddy EGT gauge.

While the core EGT temps are high, I *DOUBT* the manifold exterior surface itself sees that kinda temps.
If you're getting the turbo exhaust manifold surface above 1700F, I'd think the motor would've killed itself a long time ago.


-Ted

saxyman990

900C is less than the melting temp of pure brass (~925C). Plus, the brass plugs from home depot are not usually pure brass (they usually have nickel as well), which will increase their melting point. But IMHO, that's still getting close to the edge. You can probably use a brass plug and get away with it, but really there's no reason NOT to use a steel plug. They're virtually identical in price (i.e. cheap) and just as easy to source.

Sorry 4CN Air, can't really help you with your manifold issues. Good luck

-Rob

BMike

Is this turbo brand new? If so, call whoever made it and see if you can work out a deal to swap your current turbine for a .96 undivided, it'll suit your needs much better and many places don't have much of an issue swapping out brand new housings for others for next to nothing. I'm running a 1.15 divided, but my manifold was built from scratch for the setup and has 2 seperate runners to a single WG and is divided all the way out.

4CN Air

iTrader: (7)

I also used studs wih brass nuts to attach the turbo to the manifold. I've always used brass on exhausts to prevent seizing, although this is my first rotary. Are we seriously to the point where we're melting metal off of contact with the manifold? Then even steel braided lines couldn't come in contact with the manifold because the steel would heat up and melt the inner rubber.

I think I've solved the manifold/ tubine housing issue. I'm gettign a lager non-divided from the guy whom I bought the manifold from.

RETed

Yeah, Home Depot usually also carries the steel ones, but I needed them that DAY, and the brass ones were the only ones that were available. :P


-Ted

Turbo23

iTrader: (4)

i used a brass plug in my old stock Fc manifold as well, no problems

4CN Air

iTrader: (7)

I'll be switching to steel just to be sure, because if it fails it could end up going through my turbo. I'll continue using brass nuts though, I highly doubt they fail. I don't believe they are 100% brass, def not soft enough.

4CN Air

iTrader: (7)

update:

brass plug: $0.89
steel plug: $0.09

lol