AHOY. Im new to the forum and have several interesting questions. I am looking to buy an 3rd gen 93 FD from a friend of mine. i work for a car parts store and hes a mechanic. ANYWAYS..he owns the car, and its to say the least SEVERELY mod'd..in a good way.

i am some what unfamiliar with rotary but, not with cars in general. heres the kick.

Jim, who owns the car got an engine from a guy that worked at Mazda testing FD's and the b13. the engine has no records of where it came from and the contact that he got it from is back in japan. Either the engine is from japan and privately built or its a Cosmo (cosworth?) engine. Also, the ports on this car from my understanding are ENORMOUS (i have a templet, i will take a pic and upload it). the 2 outside ports and huge.

anyways...the mod list goes as follows....the random engine...electromotive CPU, new radiator, new fuel system (injectors, lines ect..), garret 70 turbo, BOV, apex i inter cooler, the reserve plastic pump has been replaced...new ACT clutch, flywheel, full exhaust..and a few other things i cant remember.

BUT anyways..before he converted the car to a single turbo the car ran great...but it has been sitting for a year now, untuned and not moving. everything under the hood is looking good and as far as i know, nothings clogged and slugged.


what i want to know is where would you recommend that i get it tuned. (IM in Michigan so anywhere close is fine by me) and where in gods name the engine is from.

also, the top head was dropped, so it was semi-repaired and welded. but meh.
and where could i find one of those if i could get an accurate measurement, and gaskets too.

so..ya what would you pay? and ill get that picture up.

 

WTF is the "top head"? Are you referring to the upper intake manifold (UIM)?

The closest place that does tuning is Aspec in Chicago, but I don't know if they are familiar with the Electromotive, which is not a common standalone for FDs. There are two tuning gurus, Steve Kan and Brian Cain that fly around the country to perform tuning. The third option would be to find someone local (using your regional forum) who really knows what they are doing.

Do NOT go to a "regular" performance shop for tuning, as they will not know how to properly tune a rotary.

You will also need to verify that the car is in perfect running order before tuning.

 

+1 listen to the man. An inexperienced tuner will blow your motor in 3..2..1.. especially if your car has single in it.

 

Man the first time I came on this forum just to ask how much hp my FD would make. I got similar resonses. Basically that some people believe only two humans on Earth are worthy of tuning an RX-7. Don't take everyone's advice and especially not mine. But while I sure that Steve and Brian are the best, it may not be practical for you. It wasn't for me but 465rwhp with a TO4r turbo on pump gas under 12:1 afr is good enough for me. Admittedly they wouldn't tune for timing. But I hope to one day get my car tuned by Steve.

 

mybad.. yes i am referring to the UIM..(im a bit tired) but i do understand that steve and brian are the best but im not trying to get fulled out tuned..i would just like a base tune. and then i can take the car from there, get down to specifics and the timing.

as for the engine..do you have any clues?

 

it could be a Cosmo 13b, they are known for having larger intake runners.

As far as tuning, these motors are very temperamental, and can definitely blow up in the hands of the wrong 'tuner.' Proceed with caution.

 

mmm..are the cosmos nice? the port is huge, im talking drag race ready.

 

The motor mount design does not lend itself to installation in a FD. It would take some custom fabrication to actually install it. Take a picture of it and we would easily be able to tell you what it is 13b-rew or 13b-re. The -RE has very nice intake ports but the exhaust sleeves are extremely restrictive.

 

sure thing.. ill get those pictures here tonite.

also, the engine came from a man at mazda who tested prototypes? is it possible that the engine is extremely rare?

 

here are some of the pics... the last one is of the busted manifold. =(

i am worried that if i cant even find out what kind of engine it has, if i can even find the correct parts. and i dont want to drop some cash on something i cant use.

i have some body pics i will post

 

eh, messed up on image sizes. here you go. as you can see the manifold is all fk'd =(

and its missing the inter cooler and the other half of the piping. to say the least, its a good project.

 

some more

 

last.

 

Well that is not a 13B-re and it is also not you standard -REW, it looks like you do have something rare.

 

what would u suggest it is? that manifold thats all busted, is the one that came off and replaced with a stock i believe. if u look closely u can see that the gasket were the manifold connects is really big.. in fact i think its a custom? but the guy cant find one anywhere....

this also en-lies a problem.. if i cant figure out what engine it is...how the hell am i gonna ever find the correct parts



could it be a 20b?
http://www.turborx7.com/20bbasics.htm

"20B Racing Engine specifications
Origin Possibly same as 13G race engine, but not certain.
Capacity 654cc x 3 rotors = 1962cc"

 

Here are pics of a cosmo engine, with some modifications obviously. The intake runners on the cracked UIM look like the cosmo, however it is missing the casting and is completely different in exterior design. The FD intake runners are not all the same size, the primary (inner) are much smaller than the secondary(outer). It looks like th cosmo UIM gasket might work.

 

No it is not a 20B, they have 3 rotors and 6 intake runners.

 

so.. as for the UIM on there now, what would u suggest? should i replace it with a comso one? should i leave it? and what about the internals? should i perhaps take it apart figure it out?
b/c if this engine is so rare, how will i get parts =(

 

ok.. bed time.. heres some good reading material for sleeping
i can give only a few more details..i know the motor mounts underneath like a REW i also know that the top where the UIM is, 2 bolts had to be bored out for the new one to fit. but here goes

but first...i think its either a 13 rew. or 20 rew, but i dunno.


There are two types of 13BT blocks, one from the 87-88 Turbo RX7 (FC3S GTR) and one from the 89-91 Turbo RX7 (FC3S GTX). While the older 13BT GTR block differs a lot from the 13B-REW block, the GTX block is some what a compromise in between. Most of the changes made by Mazda engineers are refinements to address the problem areas of the previous designs. For comparision purposes, the 13B-REW motor described in this article is the one from the FD3S, not one from the Japan-only Mazda Cosmo.

One significant difference on the 13B-REW is the areas around the dowel pins on the side housings. They are reinforced and ribbed with thicker castings. This is a major problem area on high output 13BT engines, as they tend to crack at high power levels and is the main reason that the 13BT blocks are not reliable beyond 400HP. Most competent rotary rebuilders will look for this before rebuilding a 13BT motor. The 13BT GTX blocks are said to be more reinforced than the earlier motors but not as significantly as the newer 13B-REW designs. Before the introduction of the 13B-REW motors, some engine builders experimented with brazing extra metal around the dowel pins area on the side housings of the 13BT motors.

The port sizes on the 13B-REW are extremely larger than the 13BT's, especially the primary ports on the intermediate housings. This is accomplished by increasing the height of the side and intermediate housing where the ports are located and relocating some of the coolant passages inside the housings. The larger ports increase the duration and "lift" of the intake stroke, allowing more air to be ingested into the combustion chamber. While the intake ports are larger, the intake runners of these motors are still about the same size. The 13BT intake manifold has a surge tank plenum which is found to create too much pumping losses because of its large volume. The 13B-REW intake manifold is a "Dynamic Pressure Intake System" which eliminated the surge plenum tank and has opposed-facing secondary intake runners. This new design enhances intake flow by taking advantage of the strong pressure waves inherant in rotary engines. The throttle bodies on the 13BT are 3x45mm, while the 13B-REW are 1x45mm + 2x50mm.

* Intake Runners: Upper, Lower
* Plenum: 1, 2
* Runners: 1, 2

Contrary to popular beliefs, the 13BT's and 13B-REW share many internal components. The 13B-REW rotors are interchangable with the 13BT GTX rotors, although they don't have the same part number and thus are not the same part. But they do have the same compression ratios of 9.0:1 and they weigh the same. The CR of the 13BT GTR rotors are 8.5:1. I believe the later model rotors are manufactured from a more accurate milling technique while the older ones are left partly casted. This is evident in the bathtub faces of the rotors.

Almost all the internal seals and springs are the same parts in the 13BT and 13B-REW. This includes the 3-piece cast-iron 2mm apex seals which are found on all post '86 rotary motors, both turbo and non-turbo. With the exception of the side seals and corner seal springs, all the other rotor parts of the two motors such as oil seals, rings, springs, side seal springs, and corner seals, are the same parts. The newer design corner seal springs are reccommended for use in all rotary rebuilds.

The eccentric shafts for these motor seem to all look the same, but the 13B-REW shaft has a larger oil bypass/crank pulley bolt. The newer motor surprisingly maintains the same warm-up oil-bypass pellet as the older motors. The 13B-REW motors does have larger front-end thrust bearings than the 13BT motors. These larger bearing components require the use of a different front counterweight. The larger thrust bearings allow better loading and thus a tighter torque setting of the pulley bolt. This design will reduce the chance of the eccentric shaft bending at the front section, which is sometimes a problem on high-output 13BT motors. The large thrust bearing is probably also designed for use with the pull type clutch assemblies found in the FD3S.

The front cover of the 13B-REW has one more attachment bolt which prevents the gasket from blowing out, which is a problem on the 13BT motors. These front covers are interchangable between the two motors as the bolt patterns are the same (except for the one extra bolt on the 13B-REW). The 13B-REW motors uses crank trigger sensors mounted on the crank instead of the crank angle sensor (CAS) on the 13BT. The crank trigger sensors allows a better accuracy resolution because of its wider teeth spacing. Also, torsional flex on the crank angle sensor shaft causes inaccurate readings. The two triggering systems has similarities in the numbers of triggering teeth. The 13B-REW's crank trigger has 12 syncro teeth and 1 home tooth, while the 13BT's CAS which spins at half speed, has 24 syncro teeths and 2 home teeth.

The rotor housings on the 13B-REW motors are refined for reliability. Since the motor is designed for higher standard output, the wear surface on these housings has a carbon-graphite coating which is said to exhibit 32% less friction than the 13BT motor's fluorocarbon resin coating. The new coating actually allows less oil to be injected into the combustion chambers, thus the 13B-REW requires only two oil injectors instead of four. In addition to this coating, these rotor housings has the water passage machined around the spark plug areas to increase cooling at the spark plug tips. This modification is similar to the ones done on race motors.

The stationary gears on the 13B-REW are factory hardened. They are interchangable with the 13BT's, provided that the 13B-REW's thrust bearings and front counter weight be used. Inside the stationary gears, the standard main bearings on the 13B-REW motors are the multi-holes type and are locked into place by an anti-rotation set screw. This design, similar to the "3 window-type" bearing is pioneered in the earlier LeMans and IMSA motors. The holes allow extra oil to flow around the oil groove thus providing a thicker oil film for the eccentric shaft to ride on. The 13BT has standard bearings with no oil holes. Oil pump capacity and pressure are also increased in the 13B-REW motors. The oil pumps are not interchangable. The 13B-REW oil pressure regulator is interchangable with the 13BT motors and is a reccommended upgrade when power output is increased. Also, a new oil pan design on the 13B-REW motors helps to minimize air induction into the oil strainger. A thinner pan with a inner bulge maintains oil level to keep the oil strainer submerged in oil. The 13BT GTR blocks use mechanical oil metering pumps, while the 13BT GTX and 13B-REW blocks use electronic oil metering pumps.

The water pump of the 13B-REW is probably the only reverse rotation water pump assembly found on any Mazda rotary engine. It is driven by the back of the serpentine belt. The water pump housing assembly on all the rotary engines are interchangable, but the appropriate front cover/pulleys/etc... must be used.

Fuel injectors used in the 13BT motors are 4 standard Nippondenso top feed rail injectors rated at 550cc. Depending on production dates, the 13BT motors had both low and high impendance ratings. The 13B-REW motors has 2x550cc injectors for primary and 2x850cc injectors for secondaries. This higher fuel capacity is for higher power levels. These injectors are side-feed rail types with high impedance so it can operate cooler. They are not interchangable with the 13BT injectors.

The engine mounts locations of the 13B-REW are under the rear side housing, while the mounts on the 13BT are located on the intermediate housing. Because of this, interchanging the motors between the FC3S and FD3S chassis is a very involved project.

The tranny bellhousing bolt patterns are the same on the 13B-REW and 13BT motors, thus the trannies are interchangable with the appropriate clutch/flywheel assemblies.

In summary, because of these and many other refinements, the 13B-REW is a much more potent powerplant which can easily handle high HP output beyond for which it is originally designed for. Many of these refinements are shared in the designs of the 20B-REW and 13B-REW of the Mazda Cosmo.

 

weird looking.

 

If the engine has good compression you do not need to tear it apart, chances are that it has the same internals as the other 13b's Mazda produced. They did not change much with exception to the compression ratio of the rotors.

You have an engine management system so there is no reason you cannot get it running, as long as the engine is healthy. It appears that you have the stock FD secondary rail with stock sidefeed injectors, those will need to be upgraded if you want to push any real boost with that big turbo.

Most of the parts you would have to worry about buying for it appear to be FD, waterpump, alternator etc. None of the sensors are Mazda they are part of the engine management. The turbo is aftermarket, the clutch is an ACT. The UIM is an issue, but you could either port match it to mate to the LIM evenly, change the LIM out for an FD and port match it or continue searching for one that matches your cracked one.

In the mean time you can be putting the car back together, there are vacuum line running everywhere that need to be removed/connected and nipples that need to be capped. Looks like there is wiring that needs to be done inside the car, and a ton of cleaning up to do.

 

the injectors are not stock, as far i as i know the primary's are 750? i think.. and the secondary are around 1600..they maybe on the stock rail..but i really havent looked at the car VERY VERY close yet..i just want to know if its worth buying and making a little project out of it.