Tales from the Batcave (RX-7, rallycross, misc. stuff content)

bruceman said:

You said somewhere in this thread that bridge porting was the best thing you did to your current engine.  What did you mean by this?

I have an old 12A IT7 car that I drive to track days.  I've installed an EFI Hardware IDA type throttle body on a RB IDA intake manifold, light flywheel, 4.777 FD, and am running Microsquirt. This is good but I want more giddy up.   I could BP a spare 12A or I could rebuild/port a renesis that came out of my Rx8 (low compression) and install it.  Also have S4 6 port in the basement.  What would you do?

you still have the old rx8 motor? I thought you rebuilt that one...

More catching up.

Last week, I was able to borrow a rotary compression tester so I could quantify my engine.  Friend who owned it warned me that the test is only valid hot.  I pointed out that it doesn't want to start hot or cold, so why bother trying to get it running, so I can go put fuel in it, so I can pray that it restarts at the gas station, and then warm it up?

Anyway, results of compression test.  Front rotor.

Rear rotor.

Great!  Except... this is the 13B in my '81, that I bought four years ago and hasn't actually run in at LEAST that long.  With a nearly dead battery, not how slow it is cranking!  Cranking speed really needs to be 200rpm or so.

Here's the compression on the front rotor of the engine that I just rebuilt, like, a month ago, after having been in the car since 2012.

Rear.

The dust that I saw on top of the throttle body.  (I had wiped some of it off to verify that it was dust and not staining)

And... the REASON for the dust!  The air filter disintegrated.

So I did a probably $1500-2k in damage because I wanted to run a $30 Spectre filter instead of a $60 K&N....

Started pulling the engine at 8pm tonight, because it got silly hot again and I wanted to work very late in the evening.

Primary ports had fresh, clean oil in them.  I use Brad Penn/Penngrade 20W50, which is green in color.

Secondary ports were full of nasty black oil.

Engine is currently held in by one bellhousing bolt, and is dripping itself out overnight.  Will pull and disassemble tomorrow after work if I'm not blasted by the heat.  Seems like I just did this a couple months ago.

Engine is apart, and I found the worst thing possible: nothing that screams "This is why compression fell away!".

Front side housing has a good delta wear effect going on from dust, but it is no worse than the rear rotor.  There is evidence on the front side housing that the rotor kissed it a little from the overrev event, but none of the seals are pinched in the rotor.  None of the apex seals for corner seal springs appear to have flattened.  Side seals seem kinda soft to push in, but they all measure even for wear.

I am stumped.  It started like it had low compression, it TESTED as having low compression, and I ain't finding a smoking gun that says "This is why compression is low, dumbass!".

I am thinking I should grit my teeth, send the side housings out to that shop in Michigan to have them ground and re-Nitrided (at horrific expense), replace the side seals and side seal springs, and pop it back together.

This will, in fact, cost as much as I can buy a used series 2 6-port RX-8 engine.  I am pretty sure my Megasquirt will be able to control it without drama, and I already have an RX-8 header, and I recently acquired a complete single-pipe Racing Beat exhaust system.  If I had an automatic counterweight, I can throw my lightweight flywheel on it and keep on using smoothcase transmissions.

Arg.  What to do.  The RX-8 engine has future-proofing involved.  But the bridge port engine makes everyone, including me, smile.

Okay.  So.  Options.

After inspecting everything in the 4 port 13B more closely, I have no berking clue what is wrong.  All the seals look decent.

The rotor housings are still kinda warped looking even though I resurfaced them.  And they are both cracked at the leading plug holes.

The side housings don't look "awful" but the oil control rings have significantly more wear than they had when I put the engine in the car 1500 miles ago, and oil ring wear is the canary in the coal mine of side housing wear.

So.  Wat do.

I have three good untouched GSL-SE side housings and one good untouched GSL-SE rotor housing.

I have, I assume, a complete engine set of good unported S4 6-port housings.

All those, and some hoarded oil rings in good nick, will get me an engine that will make maybe 200hp on a good day, with my existing throttle body and the 6 port Holley manifold I have, that needs a little bit of work to be usable.

I won't be happy with 200hp.  And I don't want to assume that my existing seals are okay.

I COULD send my side housings out to that one place, and $700 plus shipping later, I get back ground, lapped, and re-Nitrided side housings.  That $700, plus new seals and springs and stuff, will get me back my horsepower.

I think.  I am kinda having doubts.

I honestly dunno.  I made an offer on a certain rear drive Mazda B-engine and Miata trans swap, that plus a turbo might get me 200hp as well.  The same as using parts I already have lying around.  But somehow it is more enticing, even though it means less real power since turbo engines need to make around 50% more power to be equal speed-wise to naturally aspirated engines.

I also still have that LS2 oil pan/pickup, and aluminum Envoy 5.3 engines are VERY cheap since they aren't swappable due to the oil pan, and they have crap cylinder heads.    But for all that expense (engine: 500, trans: 500, HPTuners: $650, driveshaft: $500, and still need radiator and exhaust) I could save effort and get an NC 5-speed, a 2.0 Ecoboost, and a Motorsport controls pack for said Ecoboost.  This would give almost as much horsepower as the rotary I just hurt, but would grind up transmissions even faster.

Knurled. said:

I honestly dunno.  I made an offer on a certain rear drive Mazda B-engine and Miata trans swap, that plus a turbo might get me 200hp as well.  The same as using parts I already have lying around.  But somehow it is more enticing, even though it means less real power since turbo engines need to make around 50% more power to be equal speed-wise to naturally aspirated engines.

 

Huh?  I'm pretty sure wae's Neon when it was running a 2.0 turbo setup didn't have 50% more power than me, but he'd usually have 1.5-2 seconds a run on me.  I know he's a better driver than me, but I'm not sure it was by that much.  I'd think, properly sized, a turbo doesn't need to make more power, as you can broaden the powerband with it, so you're less likely to be in a bad place RPM-wise.

In reply to eastsideTim :

The 50% figure is one I have seen bandied around when considering horsepower versus actual time/mile on actual roads that have curves and such.

I have driven Evan's Miata extensively, and it's a hell of a lot of fun, but it feels like the powerband is about 2000rpm wide, and I'm not good enough a driver to properly exploit it.  The engine I just hurt made good power from 2000-3000rpm to over 9000.  <insert meme.h>   Naturally aspirated rotary is a very addictive drug.

While researching/lamenting SR20DETs (WOW they have gone up in price), I remembered an engine option that I'd clean forgot about.  And it's technically a Mazda.  Need to have a think.  (FE3 engine, which is an 86x86 2-liter that looks like a 5/4 scale Miata B6 engine, with internals stouter than the SR20DET)

While thinking, i need to get that damn '81 on the road.  Which will involve, amongst other things, removing the fan to install an FB fan, since the FC fan has negative clearance to the fan shroud.  Removing the fan involves pulling the studs out of the water pump pulley flange, since there isn't enough room to get the fan clutch past the studs.  And I am pretty sure I boogered the threads when I installed it.  Ugh.  On a brighter note, I discovered that Racing Beat actually lists a air filter for their Dell'Orto air cleaner assembly as of their 2016 catalog, so I will be giving them a call on Monday to make sure it is still valid.

Not really remembering what the stock 2.4 pushes, I did a quick google search which brought me right back to Tim's thread on neons.org from 6 years ago asking the same question!  Based on someone else making 147hp/151ftlbs on a 2.4 on the Dynojet, let's assume that's a good number.  Based on the amount of horses that Jamal found in my self-tuning mess, we can safely assume that I was leaving plenty on the table so 150% of Tim's 147hp would be 220 at the wheels.  I would guesstimate that I was only making about 160-170hp at the wheels based on a stock 2.0 DOHC putting 115 to the front wheels.  Being generous, I'd put that at about 15% more power than his car.  It was enough of a power boost that I was a second or slow slower in his chassis and I actually thought I had broken his car because it wasn't accelerating fast enough.  So that 50% number might be less applicable to small turbos that spin up fast on short rallycross courses.  Maybe?

On a rotary note, what about a Renesis engine?  Are those in ample supply still that you could run one of those?

In reply to wae :

I have been looking into 4 port engines from automatic cars.  They are more or less worthless on the used market because they aren't 6 port, and the automaticness means I can bolt my 225mm clutch SR aluminum flywheel to the counterweight so I can mate it up to my N/A smoothcase transmissions.  (Manual trans RX-8 have large diameter flywheels like Turbo II and FD)

I do have an RX-8 header. I do have a complete single-outlet Racing Beat exhaust system.   I am pretty sure my existing Megasquirt can natively read an RX-8's 36-2-2-2 crank sensor and output properly to the four coils.  The problem I have is a philosophical one:  I can't see spending money to make less power.  Even a built 6 port RX-8 engine makes less power than I used to have, and a whole lot less midrange torque.

Srsly, my current eBay watch list is hilarious.   I have a 4 port RX-8 drivetrain with manual trans, a set of new '71-73 12A rotor housings (for teh RX-3), a complete set of NOS 6mm apex seals, two listings for stock exhaust manifold for an S2000, some more 12A end housings, an NC 5 speed transmission, quite a few '99-01 NB 1.6l/5 speed JDM drivetrains, some 4AGE 20v engines, a '09-up RX-8 6-port that is either blown or the guy has no idea what he is selling, a couple BEAMS 3S-GE drivetrain swaps, an early WRX drivetrain swap (probably should delete that one...), some NC intake manifolds.... and a complete Evo IV drivetrain with front crossmember.  I don't own the S40 anymore, I should probably remove that one too.  Or buy another S40.

In reply to Knurled. :

Im not sure what size EvanB’s turbo is, but I wonder if it is maxed out or not.  If it’s got some overhead, you could run a smaller turbo and get your wide powerband.  Also, how about an F2T?

In reply to eastsideTim :

He has whatever the stock Mazdaspeed turbo was.

The FE3 is an F2T on steroids.  Diesel block and crank with a DOHC head.

eastsideTim said:

In reply to Knurled. :

Im not sure what size EvanB’s turbo is, but I wonder if it is maxed out or not.  If it’s got some overhead, you could run a smaller turbo and get your wide powerband.  Also, how about an F2T?

It is at 10psi. It feels better at 13-14 psi but i had some problems last time i tried that...

In reply to EvanB :

By my recollection, it worked out okay for just long enough.

Also:

I have lost interest in making the black car's engine Perfect, and gained intentful interest in just getting SOMETHING in there that runs, as quickly as possible.

Oh yeah, I should mention.  Teh R decided to start puking the trans fluid out from somewhere in the bellhousing, at a phenomenally fast rate.  R is currently at Evan's place, and I am driving teh Montero for the time being.  (Thanks Evan)

Talked with our trans guy.  (He's so good, he only does bench jobs because he has no time anymore to do R&R himself)  He said that it is really common for all Aisin-Warner transmissions to grab the converter support bushing and twist it out of the pump, which will also destroy the seal.  He said, worst case, I need a converter and a pump.  Best case, a bushing and a seal.  He said there isn't any real rhyme or reason why it happens, the wonky solenoid pack (I have a pre-Fix TF80SC.  Fix was done mid 2007 model year, I have a 2005 build '06) will have no effect on it.  I mentioned that it occasionally slipped/shuddered at high power in 2nd and 3rd, he said nah, completely unrelated.

So, great.  I may not have exploded the trans.  But on the other hand, the trans kinda needed rebuilt ANYWAY.  I am feeling pangs of While We're In There happening.  The problem is, the amount of money I had to put on my credit card to cover fuel and other expenses related to the transplosion neatly cancelled out the extra payment I made this month to try to bring the balance down to sub-$2k. (I think I actually owe less on teh R's loan than my credit card, at this point) And the black RX-7's engine still needs to get rebuilt.  So I am not exactly thrilled about the idea of flushing a ton of money at the Volvo if I don't HAVE to, but trans R&R is a daunting enough task that I may bite the bullet and Do It anyway, so I only have to go in there once.

Yes, I will be resealing the angle drive.  The axle output seal has been leaking since I got the car, about 2 ounces of gear oil every 3000mi.  You bet your ass I have been checking and refilling it at every opportunity!

Of course, Level 10 makes a high stall converter for the AW55 ('04-05) but NOT the TF80.  And what this car desperately needs is a high stall converter.  The S40 had a 3000rpm stall converter and a tiny turbo, kind of ridiculous actually.  It would flash up to full boost instantly.  This car... is the opposite.  Huge turbo and I think the stall speed is under 2000rpm.  I'd love a 3k stall speed converter like the S40 had, it would really wake this car up.

Of course, if I rebuilt/beefed the trans, then I'd have no excuse not to pull the cylinder head and shim the block so that I could safely get up over 400hp at the crank with a tune and some mild turbo upgrades.  Because why not.

https://www.youtube.com/watch?v=qhzjKWaRf4k

We HAD one of these CNC mills.  This, $1000 to Darton, and a lot of work, could have got me this for teh R.

In this thread:  "My trans broke.  How can I reliably make the engine make more power?"

(says the guy whose RX-7 goes through more transmissions than oil filters, and whines that he wants more power...)

Not sure if it helps...

I have 1 known good 12A that was rebuilt by mazda a number of years ago.  It was in a racecar and I have no plans for it at the moment.

I also have an unknown condition 12A that supposedly ran, but I have not verified that.

I also have a good running 13B 6 port (87).

Let me know if you have interest in any of these.  I would LOVE to trade for a GSL SE gas tank....

I want one of those 12As regardless!  I do not have a -SE tank but i do have lots other stuff.  Maybe even money.

Well, come back out to my garage.  

You still have that 13b I sold you, or maybe it was going to Evan?  I didn't even realize it had a racing beat flywheel on it until you pointed it out!

Seven 2 fore 858 o six 75

In reply to wvumtnbkr :

There was one that he picked up for me in the Quantum that went on to Chris for the Rally RX7.

And I recall it was a 12A that had the lightweight flywheel, because you tried to sell it to me and I didn't have enough money, and as it turned out that car was very sketchy with as much weight as there was in the back, anyway, so the rainstorms I had to drive through would have went from white knuckle, to possibly waiting to get extracted from a ditch.

Also, it was a flat faced steel flywheel, and therefore for a 215mm clutch, which is kinda unusual nowadays.

Ah gotcha.  I had only really played with s4 engines at that time and didn't know anything about 12as. 

Let's get this transmission out on a tray.

Nice.

There’s a showroom fresh looking rx7(the body style you have) up the street from me for sale with some gold mesh wheels.  Just south of my house on same side of street if you’re out and about and want to be tempted 

In reply to Patrick :

I have more debt (both pending AND current) than I care to think about at this point, and six cars that do not run.  I am staunchly ignoring all temptation.

I find it interesting that I have two Mazda rotaries with no engines, two AWD heavily turbocharged low compression five cylinder cars with no transmissions, and two complete cars that would run if only their fuel systems were not full of vile goo.  The Quantum is inop mostly because of lack of inertia.  I COULD put a trans in it, but I kind of want to put one of those keen spiffy 60-1 rear main seal slash crank sensors in it before I do, but those cost a lot of money, and I don't want to spend that much money, so I don't buy the sensor package, but I don't put the trans in because I want one of those sensor packages...

I mean, okay, it also needs me to cut up the intake manifold and make a new plenum (which also requires me learning/becoming able to weld aluminum) and it needs an intercooler and it needs some form of odd cylinder capable engine controls, but other than that...

Good news!  My trans guy said that the Volvo's trans looked excellent inside.  Practically no wear on any clutches or bands he saw, no sediment in the case, the filter was clean, etc.  The pump, however, is completely shot, he said the gears were actually broken.

I, er, MAY have bounced the rev limiter a bit shortly before the transplosion.  Not that this should have been a problem, the trans is rated to something silly like 325ft-lb when upshifts are made at 7000rpm, and teh R's redline is around 6500 or so I think.  Well inside the manufacturer's rating.

Anyway, since the shift issues are rather sporadic and can be addressed at a later date without trans R&R, and the rising realization that replacing the angle drive and collar are not going to be cheap, I opted to just replace the pump and some seals.  I am, however, having the converter rebuilt just to be safe.  There's a shop we deal with not too far from here that does excellent work and has a no-BS warranty ("if you break it, we will fix it") and the converter is now languishing at their place.  Hopefully all is OK in there, but there's no way to know without cutting it open, and once you cut it open, you might as well just rebuild the thing.

Oh yeah.  The splines on the angle drive and the drive collar are worn most of the way through.  If this didn't happen, it probably would have failed in a few thousand miles, probably in a situation where rear torque was needed in an emergency so it would go to 100% right away.  In other words, perfect storm for failing in the winter.  Ugh.  So, I'm sucking it up and fixing it now while it's all apart.  Better now, than when it is 10 degrees out.