I'm building an FD/T2 hybrid motor going in a 1st gen. I have access to the stock twins and a T72 turbo from cxracing. I'm leaning to the T72 as we all know the stock twins kinda suck. And I think the rear is beginning to leak oil.

quickie turbo specs are P Trim .96 A/R Turbine, watercooled. More info can be found here http://cgi.ebay.com/ebaymotors/ws/eB...=STRK:MEWNX:IT

hybrid engine specs:
FD side plates
S4 T2 rotating assembly
rotors milled to 3mm
BIG streetports
FD intake manifolding and stock injectors for now (will do 720/1600 after break in)

Which turbo would you use? I like the T72. It's new. Gives me an excuse to use my Precision Turbo 46mm wastegate and build a tubular manifold and screamer pipe for them. 3" full exhaust.

The S4 T2 rotors are low comp, like 8.6:1 or there abouts so we plan to run really high boost and a big FMIC (lots of room in a 1st gen). Milled for 3mm apex seals which people have said gives a bigger margin. Competition outer oil springs should help seal combustion chambers from the crankase a little better. NF01 (20B/FD) corner springs are always a nice touch. Solid old school corner seals, not the newer atkins design. Why? Because I have a set sitting here.

I've got two sets of 3mm apex seals here. OEM and Atkins. Which would you use? OEM can shatter and take out a housing and rotor. Atkins can bend and break a little bit off possibly saving the housing. I've seen this and it encourages me to go atkins.

Is the T72 a good match for my planned engine? Thanks!

 

Man honestly I wouldnt try to spend time and money building a good engine and then using a knock off turbo. I would say look for a secondary turbo cartridge and use the twins

 

Well the guy I'm building it for has always had an interest in using a cheap chinese turbo and making 400hp on an FD-like engine in his 1st gen, kinda similar to what z-beater did a few years ago. So I began collecting parts to begin piecing this setup together. I have access to the stock twins as well so I figured I'd ask.

The twins have unknown mileage but it looks kinda high. A bit of shaft play on both. The rubber coolant lines were swollen(stretched out) and ready to burst. Glad they didn't. Heh.

I wonder if it would be easy to fab up a downpipe from the stock twins in a 1st gen? For that matter I wonder how much it costs to replace the rear?

I already have the cheap chinese turbo. Might as well use it, right? I was just wondering if it's the right size for my planned engine.

 

T72 is gonna be a bit laggy but come on HARD. If you want big power and are not worried about response it should work. (that is if the knock-off is similar in specs to the real deal, I'm too lazy to do any of your real research for you, I hope you go look at exducer/inducer blade sizes yourself). IIRC the real T72 is used for CONSIDERABLY more than 400whp

Little tip though, the turbo miata crowd (my other forum addiction) has been using CX-racing turbos and intercoolers for ages and making big power. Most the guys there recommend using a real turbo if you can swing it, but there are plenty of successful builds using the CX ones. The CX intercoolers are the industry standard though. EVERYONE uses them.

 

you realise that for the same absolute or final compression with the ~8.5:1 rotors vs 9:1 of FD is only 20psi vs 18psi, it really isn't as much of a difference as people make out.

That is a lot of compressor for that power, do they do a knock of with T04Z size compressor? would spool faster, you would just about streatch to that with T04B in T04S compressor housing wouldn't you, much lighter compressor to spin up.

 

now I don't know what your experience w/ the "older" solid atkins corner seal design is but I can tell you that my last engine used those and they definetly cause more wear than stockers. I will not be using them again. I was affirmed by quite a few people that stockers are perfectly fine (yes, even for hiboost apps). I'm pretty sure it was ErnieT who confirmed that fact.

 

I originally got this turbo for a 20B, but as I learned more about it, I determined it shouldn't be boosted. The 20B is a very early and has weak castings and a weak shaft apparently. Plus it's been ported so the power is in the ports. If I boost it I'm asking for trouble. If the ports were left stock, this turbo probably would have been perfect. I guess it could still be used on the 20B but should I tempt fate? I'd rather run it like gmonson and keep it simple NA. It's going in a 1st gen so I don't need 500HP.

tasty danish, were threw around the idea of going half bridge to spool the T72 up faster.

Do you think a half bridge would be worth the idle trouble and super rich tune required to make it streetable like a regular streetport? The guy already has a blow through DCOE on a streetported R5 13B and it isn't very pleasant to drive daily. It essentially runs like a half bridge already lol. He'd prefer to make an upgrade in drivablity when he upgrades to EFI. I don't blame him.

The other option is to sell the turbo and look for something smaller, or use the stock twins if they are even useable at this point. I'll go inspect them later today.

The guy is definitely getting a cx-racing intercooler. Already has one picked out. I'd like to think their turbos are at least half decent. There's just something about using a massive turbo on a rotary that makes my Levis swell, you know? We just need to make sure his engine will spool this beast at a useable RPM (below 3k or so?).

slides, we're using S4 T2 rotors because I don't have any FD rotors available, just the side plates and manifolding&twins. Plus these are already milled to 3mm and look to be dynamically balanced. Also have a rear auto counterweight.

I checked the side seals yesterday and swapped several to be closer to .003" like Judge Ito recommends on a boosted engine.

The corner seals are old school OEM such as those found on 74-75 engines. They're what I had on hand. I'd imagine they'd wear the side plates similar to 76-83 hollow corner seals, but then again they are slightly heavier and have more surface area.

Lastly I have Atkins and OEM apex seals in 3mm. I wonder which set to use?

 

Here are the FD parts I was talking about




Doesn't seem too cracked. I understand these little cracks are normal.


Front turbo looks a little dirty. Maybe because it's used all the time compared to the rear? Doesn't appear to be leaking oil as far as I can tell.


Rear might have some oil leakage. Could this be from sitting for a few years? Will it smoke on startup?


I've got two manifolds. If I use the twins, they'll be de-sequentialized or whatever it's called. So I'd grab the better of the two manifolds and remove the wastegate, block the hole with an iron NPT plug (as recommended) and also do the recommended mod to the Y pipe.

I'd still prefer the new T72 though, if it can be used.

 

You have nothing to lose by running the T72. I looked at the specs, and it uses the same size turbine wheel as a true P-Trim (so if lag is a concern, you can source a divided P-Trim T4 housing), and same with the 72mm compressor wheel. Even though this turbo is rated to over 600whp on a rotary, if you run it at ~15 psi and get 400whp, you should be right in the middle of the compressor map for efficiency. So basically, as long as lag doesn't become a concern, go with it. Just make sure you route the wastegate half-decently to control boost, especially for break-in with stock injectors. And also, realize that the difference between stock twins and this turbo are huge! So it will come down to what you want out of the car.

And hey, if you will be building your own manifold, I would recommend building it with a divided T4 flange now so that if you do decide to in the future, you can swap to a divided turbine housing. They pop up for pretty cheap on the net here and there for P-Trims.

 

Thanks for looking at the specs. I don't yet know enough about turbos to know what to look for. I'm very glad I can use this turbo. Makes my day. Thanks man!

This is the flange I got for it, but I chopped out the divider thinking it would go on the 20B. These are cheap so I'll get another. Oh and they're actually threaded for 10mm x 1.5, same as Mazda exhaust studs. http://cgi.ebay.com/ebaymotors/T4-DI...item518f7d5cee

This is the wastegate I got. http://cgi.ebay.com/ebaymotors/Preci...item1c1b5937c2

Question. What's it like to use a single wastegate on a divided manifold?

 

**EDIT** take this with a grain of salt, as I'm stuck in 13B land. 20B may be more reasonable. Just reread the thread after posting.

Whoa whoa wait a sec. Spool under 3k? NO WAY is a T72 going to get NEAR that. You're looking at 4500-ish (edit: maybe not on a 20b), regardless of port. Honestly, you will almost not read about a turbo that spools that low on this forum at all.

If you want spool that quick, stock is the only way to go, or like a stock s5 if you want single. A "fast spooling" single is spooled at 3500 on these engines, with some really optimized set ups getting closer to 3000-3200.

Single wastegate divided manifold shouldn't matter. Technically you are joining the pulses but you won't notice the difference.

And I wouldn't make the porting MORE aggressive and expect it to be more streetable. yeah bridges will spool faster, but what is a turbo engine before it spools? An N/A engine. meaning you still pull away from lights like ****.

 

Hey, this turbo is going on a 13B with some parts from FD/S4 engines (taken from first post) so you are on the money. However more aggressive porting can actually gain you some bottom end and spool the turbo faster, it just idles worse, gets worse fuel economy, etc.

I'm sure the flanges and wastegate will be fine, I would go with TiAl myself but that's personal preference. Single wastegate on a divided manifold is simple, you just join the two runners into a common v-band flange. If you want to go fancier, you can keep the two runners completely divided up into the flange seating against the wastegate valve. Turblown I believe has some pics floating around here of doing this.

As tasty danish said, you will not spool a T72 before 4000 RPM easily. Especially not with a 0.96 A/R un-divided. If increasing spool is more important then pure top-end flow, go with a divided 0.84 A/R T4 housing for that turbo, and a fully divided manifold. Going with a half-bridge could also help get your turbo spooling quicker, and higher compression FD rotors can help make your engine feel more responsive in lower RPM's. If you search around you might find some people's results from porting on spool time.

 

Coupla things:

the WG is located in the front section of the shared turbine housing. That flapper door in the exh mani does need to be removed however. Running both twins togther is called 'non-sequential.'

After seeing pics, I wouldnt use those twins, they're junk.

I think I mentioned this via PM, but that chinese turbo is best used as a paperweight. Expecting it to perform like a Garrett or Borg-Warner is just foolish, no offense Jeff

 

For the record, this setup is going in my FB.

Honestly that compressor is sounding way too big for my needs; at 400 WHP I'm going to be breaking drivetrains and I'd rather not go to a Ford rear end if I can avoid it. I don't care too much if I don't hit 15 PSI until 4K, but it must at least have a usable amount of low-end grunt. As it is now, do you think it would be annoyingly laggy, or just laggy? What about if I got a .84 divided T4 turbine housing?

And I don't have particularly high expectations for the longevity of this turbo. When it goes I'll replace it with a Holset or something. The point is that this one is available, and we're wondering if it would be a bad idea to use it.