sinfestboy

whats better about the FD engine than a TII? If I had a TII with a broken engine, would it be worth it to swap an FD instead of fixing the TII engine?

rico05

Not really. A 13BT will perform the exaxt same as an equally prepared 13BT-REW. It has basically the same "block" if you will. The biggest difference is that the REW came with twin sequential turbos, as apposed to the 13BT's single TO4 unit. But, mabye I am wrong. I own a n/a for God's sake!!!!!!

TPDNRX7

An FD engine has stronger dowels, stiffer apex seal springs and better internal bearings. Ask BOOSTED7 why his rear housing cracked on his 13BT. Thats why FD engines can handle more boost with the proper tuning.

vaughnc

sinfestboy,

The series VI engine has lighter rotors and slightly tweeked exhaust & intake ports. It's designed for higher boost levels from the twin turbos.

You'd want to swap in the twin turbos, ECU, FMIC, injectors, etc..

Truth is the Series IV and V engines in the 2nd gens will give you similar HP numbers with a few mods. The TII's powerband is almost as flat as the twin setup.

The Series VI engine has better low end torque and more volume from the turbos. It also has a more complicated turbo setup that can get funky if you don't keep it well maintained.

-- vaughnc

sinfestboy

alright, I am currently in the midst of reading "maximum boost" by corky bell, so I am totally redefining what I know about turbos.... so here goes yes, ANOTHER question

In a sequential twin turbo, the setup is like this: intake---compressor 1---compressor 2---manifold---Enging---manifold---turbine 2---turbine 1---exhaust. correct?
now on a normal TT setup (not sequential) the 2 turbos are totally seperated, and therefore, you can have smaller turbos, that can pump just as much CFM, but have very little lag.... correct also? on a sequential, it has 1 small turbo, that pumps air at low rpm, and at higher rpm, the larger turbo takes care of things.

Is all of this correct? the reason i am asking is because in that case, it might be better to take a TII, and make it a TTII. That way, much better throttle response, low boost threshhold, and you can pump just as much air. while in the FD engine, you are limited by the amount of air that the smaller compressor can pump before it gets into trouble.

I am sure that none of this makes sense, since I am writing this at 11:30, while watching TV. and I am also sure that its hard to decipher the question... I will be back tomorrow after school to make more sense out of it. But I wanted to post it now just incase I forgot.

wow, nothing I just said made ANY sense.

vaughnc

not as well read as you, but I would like to mention the 2nd gen has a twin scroll turbo which as I understand gives similar advantages as a TT.

Mazda designed the 2nd gen's turbo to be effecient at lower rpms. That's why it has more torque at lower rpms than the NAs. Spool time is fast as turbos go.

The turbo also makes more HP at lower PSI than similar cars from what I've read.

The 2nd gen yamagoochi book has a good writeup on the turbo setup of the 2nd gens.

-- vaughnc

NZConvertible

Everyone's talking like the twin turbos are welded to the FD engines! The FD engine is superior in many respects to the FC one. It's slightly larger ports will allow a little more power, but it's main advantages the changes that improved strength and reliability. So it's a better base for a worked engine. It can then be matched with any turbo you like, even the FC turbo if you're working in stages, or a custom twin-parallel turbo system.

HWO

ERP WRONG

the reason you crack end plates is from detonation, until you hit around 650RWHP and even then its still debatable if its really is the sheer force or from detonation again

Node

iTrader: (1)

wow this is misinformation heaven, lemme try n fix **** up. First off, READ THIS LINK!
http://www.mindspring.com/~pko/13BTvs13BREW.html
It compares bt and brew

S5 and S6 are more alike than S4 is to S5.

The 13BT did not come w/ a T04.
It came w/ a Hitachi something or other. Well S4 at least, I don't know what S5 came with.

I just tried to explain how twin scroll works but its quite difficult how I was doing it.
Ok, lets try again, the ehxuast side is divided into two passageways, only the lower passageway works at lower RPMs, spinning the "wider" half of the exhaust turbine. The wider half will spin up easier at lower RPM because there is more surface area. Once it gets to a certain point both passageways open and it spins the entire turbine.
OK now that wasn't so hard

Now lemme try sequentials. there is a solenoid that closes off the exhaust passage (not really sure how it shuts off the secondary turbo, but this is my best guess) to the secondary turbo so the primary turbo gets ALL of the exhaust gas to spin up, at I think about 4000RPM the solenoid closes and bother turbos get exhaust gas, but now there is more exhaust on account of the higher RPM.
both turbos are pretty much the same size (small as ****) there are no small primaries and gigantic secondaries, well on the cosmo TT systems they have slightly different sized turbos but theyre not very different.
non-sequential is when you yank almost all of the solenoids and vacuum lines and i think you have to weld something, and then both turbo get exhaust gas. No problems with vacuum lines popping off, and no more rats nest. The FDs sequential system is rather complicated and can fail easier than others.

Supras have very nice and somewhat simplistic sequential systems compared to FDs

ReZ311

iTrader: (4)

The 13BT (82-92) lasts longer than the 13BREW(93+) I think. Prove to me that an FD motor has reached 150,000 with hard driven miles. My FC T2 motor died at 155,000 miles HARD DRIVING TOO.

NZConvertible

That's pure speculation, not fact. Your one isolated example means nothing. Prove to me an FD can't do 155,000 miles. Just like the FC, most FD failures are due to improper tuning/modifying.

rxrotary2_7

i would have to disagree with something you said. the ports are actualy larger on a turboII, the design of them is different on and fd. they are angled down


rez311- that was just an ignorant statement. sorry to be so blunt.

another difference is in rotors themselfs. if you cant get an fd block, use your turboII block and just get a set of rotors. it will be much more cost effective for you also. intake ports dont line up, hence you need a new intake.....ect, ect

Salguod

Hey NZConvertible,

ReZ311 is somewhat right.

Go ask around in the 3rd gen forum.

FEDREX

From what I've read the FD does have stronger internals however there seem to be an awful lot of them with engine rebuilds/replacements for sale. I see a lot of 80K new/rebuilt engine cars on autotrader and so on.

vaughnc

That's what I don't get. FD TT engine need a minor rebuild around 85-120K, but the FC 13B Turbo engine with mods seems to need a rebuild around 120-140K right ?

What's up with that?

RETed

I doubt you could pull off an FD 13B-REW install into an FC.&nbsp One option requires you to fabricate a complicated set of engine mounts to make everything drop-in and/or a custom engine sub-frame.&nbsp Option #2 is to redrill the center housing of the 13B-REW and install the FC 13BT oil pan with some minor modification to the front of the oil pan due to it being too long.

Either options presents serious machining/fabrication skills, so I don't usually recommend such a swap.&nbsp A 13BT is good for 500hp at the flywheel, and most people cannot handle such a beast.&nbsp Worry about getting your 13BT up to 400hp, and then you can worry about the advantages of the FD 13B-REW engine swap.

If you want that cool look of the FD intake manifold in the engine bay, some folks found out that the FC intake manifold and throttle body fits on top of the FC 13BT engine with minor fitment issues...



-Ted

Barwick

a twin-scroll turbo is made to allow you to keep the exhaust runners separate. Look at it like this:

You've got two rotors. Each one makes an exhaust "putt" at its own time, which is (always?) different from the other rotor's time. Now, if you have a single scroll turbo, you have to take those two exhaust putts and combine them BEFORE the turbo, which could pose some turbulence or heat problems or whatever.. But if you've got a twin scroll turbocharger, then those exhaust "putts" can stay separate, and each one drives its own turbine on its own passageway through the turbo.

Here's an attempt at ASCII art to explain it. Hopefully the server doesn't screw with the spacing again..

Single Scroll
__________
| |
| engine |
----------------
| | | |
| | | |
\ \ / /
\ \ / /
\ /
| |
-------
| | <------ turbo
-------

Twin-scroll
__________
| |
| engine |
----------------
| | | |
| | | |
\ \ / /
\ \ / /
\ | /
| | |
-------
| | | <-------- turbo
-------

edit: No, it totally #*(@%ed with it.. oh well.. here's a picture I made of my art..

sinfestboy

Barwick: So double scroll is twin turbo? I am a little confused by in your ascii, you said "turbo" instead of turbos.

RETed: so, I'll have a professional do the custom fabrication. Its still possible, and it would be easier to make the big power with the FD engine than the FC. think about it, the ceiling being higher on the FD isnt the only reason.

Node: After reading that article, I thought of something... If you open up the 13bt, and upgrade some key parts, the only thing better about the REW would be that its a Twin turbo, and the ports have more room for enlargment.
So therefore, If you are gonna take the engine out and do internal work, wouldnt it be worth it to simply change the engine, since either way, the engine would be removed, and eventually out back in. and you have the (MASSIVE) advantage of having 2 turbos and bigger ports. So.... if someone did the fabrication for me at a reasonable price, it would be the better choice!

Yay, I figured something out for myself

Mazdarules

The two turbo's are not an advantage, you'll notice that every fd making big power is running a large single. The stock twins are pretty weak.

RETed

Either you have a lot of money, or you're really crazy.

I find the extra 100hp ceiling "not worth it" in my book.

I can dowel a 13BT engine and make the same amount of power...


-Ted

RETed

Actually, the design of the "twin-scroll" turbo on the 1986-1988 Zenki turbo FC is to increase bottom-end torque/power.

The turbo has two separate exhaust gas paths/runners.&nbsp There is a flapper that CLOSES one of these paths/runners.&nbsp This vents all the exhaust gases (from front and rear rotors) to just one path/runner.&nbsp At low engine RPMs, this allows the turbo to spool more efficiently.&nbsp At 2,800 RPM, the flapper opens and allows both paths/runners to vent the exhaust gases; at this point there's enough exhaust gas flowing to push the turbo efficiently...

The design was to, 1) increase low-end torque and power, and 2) to minimize turbo lag.



-Ted

rxrotary2_7

i am going to have to jump in a min ted. its not that hard. here is a picture of a current project underway...it is a little ghetto as of the pictures to date, but will be geat. it is a 91 vert with a turboII hood and mariah front end. has stock FC turbo to get it up and running, but will be made a t04 soon with a FMIC.
what was used
fd rotors, fd side housings, and n/a rotor housings. yu are correct in the motor mounts posinga problem, but like they say, where there is a will there is a way. again keep in mind, this was made out of many spare motor parts sittin around, and probobly not the BEST way to do it.
[IMG]
https://www.rx7club.com/forum/attach...&postid=462576
[/IMG]

RETed

I'm been in and around Paul Ko's FC/13B-REW conversion, and it's a lot of work!

I got into a beef with Greg Coe (is he still here?) on going with the drilled center, but he managed to pull it off too.


That's a super nice install!&nbsp Too bad the Turbo II hood has no practical use...unless you're going to use the hood scoop for something???




-Ted

NZConvertible

Like I said before, everyone's talking like the twins are welded on! You can put any turbo(s) you want onto the FD block, the stock turbos aren't a reason to not get one.
BTW, you'll notice that every FC making big power is running a large single also, no stock turbo in sight.

rxrotary2_7

hood is just becaue it was there, same goes for the mariah front cover. the vert was siting for about 3 years in need of a motor, and a friend finay got motivated enough to do it, project is going on its 3rd week this week (thats at about 4 hrs a day,not solid days so i dont scare anyone looking to do so)