12a CarTech drawthrough HELP!!
 

OK… So, I haven’t been able to find what I’m looking for by searching the forums. I’m just gonna ask everything at once.

I have an 85 RX with a 12a motor with remote (pre-79?) front mounted oil cooler and no beehive cooler. I was told the engine was street ported when I bought it. It currently has a Racing Beat intake/header and free-flowing exhaust with a Carter 500 cfm carb. The engine pulls very good… way better than my stocker before this one. I’m not sure on mileage on engine. It will hit 65 psi oil pressure by 2500 rpm (aftermarket gauge). I’m still using the stock fuel pump.

I will be installing a Cartech DRAWTHROUGH turbo setup… the model which does NOT retain the original intake manifold. The carb sits on a perch just above the turbo intake and flows out the turbo into a Cartech intake manifold. The turbo is a T25 and carb will be a 465 cfm Holley.

I had some questions and was hoping to get these answered. Thanks so much.

Is there a way to tell if a motor has been ported without completely disassembling the irons?

Distributor – Remove vacuum advance lines and retard total advance by 2 degrees?

Can I plumb the turbo’s oil drain line to the oil filler neck or does it have to flow DOWN to the oil pan or front cover?

What kind of max boost (psi) should I dare to play with? .. Resulting hp (I’m asking this because I read everything from 6-13psi on a stock 12a)

When should I be getting max boost (rpm)?

How hard to start are drawthrough setups?

When people say they are VERY hard to start in cold weather, what is considered COLD? (I live in Oregon and it was 28 degrees Fahrenheit this morning)

Should I try to monitor intake charge temp?

PLEASE… any help would be appreciated

Do you have the instructions for this kit? If not pm me and I will send them to you. I think most of your questions are answered there.

yeah.. I have the instructions.

https://www.rx7club.com/1st-generation-specific-1979-1985-18/cartech-bae-12a-drawthrough-turbo-install-instructions-780358/

These are "baseline" instructions. I was just curious if anyone out there has experimented with drawthrough boost in the way I listed.

The plumbing of the turbo oil line out im also interested in.

Is there a way to tell if a motor has been ported without completely disassembling the irons?
take off the intake manifold and look in the runner with a flashlight and stick your finger in it and feel around. lol

Distributor – Remove vacuum advance lines and retard total advance by 2 degrees?
remove advance and set timming to 10*btdc at full advance. lock the distributer as soon as possible.

Can I plumb the turbo’s oil drain line to the oil filler neck or does it have to flow DOWN to the oil pan or front cover?
oil drain has to flow down hill, no if and's or buts

What kind of max boost (psi) should I dare to play with? .. Resulting hp (I’m asking this because I read everything from 6-13psi on a stock 12a)
i wouldn't push it past 10 psi on pump gas without an intercooler. Yes you can use an intercooler, but you have to run richer to make up for the fuel puddleing in the intercooler, and it makes for some crappy throttle response.

When should I be getting max boost (rpm)?
t25 is tiny turbo max boost by say 3k rpm

How hard to start are drawthrough setups?
the hardest way to start a car, but if you get it tuned it should be okay

When people say they are VERY hard to start in cold weather, what is considered COLD? (I live in Oregon and it was 28 degrees Fahrenheit this morning)
it'll take at least three tries to get it started and you've got to warm it up for atleast 2 minutes before it'll be driveable.

Should I try to monitor intake charge temp?
sure why wouldn't you if you have the ability to.

If a were to go blowthrough.... Would i need a one-way valve for the brake booster vacuum line? Im assuming a brake booster cant take positive pressure.
With a blow through setup, how much psi would i dare??
Seems locking out distrituber and getting a boost referance FBR would work with blowthrough
Thoughts?

:stickpoke
Bump

Locking Distributer
 

I've been doing some searching on locking my distributer and found testomonials for welding weights or just removing springs.
If i remove springs and disconnected vacuum advance, would I just rev the engine and set total advance to 10 degrees advance?
Man... I really need to get a dial advance timing light.. ugh!!

Guys.. I really appreciate your input

if you lock no need to rev. Welding is a personal preference. If you don't and just remove springs, as soon as the car cranks the weights inside swing out due to centrifugal force. So when the car is running whatever you set it at is where it will be all the time. Lock that bitch and set the leading to 10 advance and the trailing to 0.

Keep your ten degree split. I know it sounds crazy and hard but it is not. I went threw all this last year on my turbo car.

If you went blow through you would need a check valve. Just ge3t a pcv valve for 8 bucks. Draw through is so out dated and in my "opinion" JUNK. Who the hell want's gas and air mixing inside a turbo right next to a 1800 degree hot side. Sounds like a bomb waiting to happen.

Locking Distributer at 10 degrees advance
 

So, on a 12a the leading timing mark is 0 degrees advance and the trailing timing mark is 20 degrees advance.

Would it be safe to assume setting timing at 10 degrees advance would be right between these marks? :wallbash:

Or, should I just buy a dial advance timing light, hook it on L1 plug wire, set it to 10 degrees advanced and turn distributer until pointing at 0 degree mark. :scratch:

Thanks guys

1st mark leading is at o 20 degrees behind that is trailing. Bump the dizzy clockwise till you get to 10 advanced. then do trailing 10 behind that. DOnt fuck with dial lights work for shit on a rotary. gonna have to remove the front pulley mark it 10mm from 0 for your leading mark.

which direction from the L1 0 degree mark am I measuring 10mm from? towards the trailing mark or away?

Is setting the 10 degree SPLIT necessary? Im sure I can find it through searching, but, do you do this adjustment via the vacuum pots?

It should not be hard to start if the carb is tuned properly and if you have a working choke. I have a draw-through supercharged setup and it starts right up and stays running easily in the mornings at similar temps to yours. However, once I start driving, my dumb electric choke sometimes kicks off too early and I have to keep it running with the gas pedal until it can idle on its own. Not a big deal, just a minor annoyance.

Read this and all your timing questions will be answered. http://www.yawpower.com/pultime.html Don't think about advance and retard as it just gets confusing... Just set timing at 10*before top dead center for leading and 20* before top dead center trailing.

Awesome!!
 

I remember reading that info a while back, but, couldnt find it again. THANKS

This will make setting my LEADING timing very easy.

But, for the TRAILING 10* split, do I use the same marks or mark my pulley to the LEFT of the 20* trailing mark?

Give me a V8 and I'm fine.. substitute 2 rotors and two spark plugs per rotor.. and it takes me a bit to grasp the concept.

This is a very simple concept. The trailing and leading are two completely seperate working ignition systems. The leading are the most important and the trailing fires after the leading just to clean things up... So when you are setting the trailing you're setting when it fires after the leading, so if you set the leading to fire at 10*btdc and you want 10* of split then you set the trailing to fire at 20*btdc... All split the split is measuring is the degrees that the trailing is firing after the leading.

I KNOW im prob over thinking this.
Im looking to do the weight spring removel dizzy lock, so, even at idle it will be full advanced.

Looks like I will be marking the pully to the right of the TDC mark (seen from front of car), making marks every 0.196" = 5* for the leading. Set LEADING timing to 10* than lock the dizzy adjusting nut. Than adjust the TRAILING advance pot until timing mark back on 20* TRAILING OEM mark???

Yes even at idle it will be at full advance. And yes. And no. Put the trailing so it lines up 10* behind your leading, so if you set leading at 10* BTDC you set trailing at TDC.
https://www.rx7club.com/attachment.p...1&d=1232746446

Hyper4mance2k... your awesome. Thats all I wanted, an easy way to visualize the timing.
I wonder why Mazda decided on a 20* split stock?
Seems most of the dyno numbers show 8-12* split is best for performance.

As an odd twist of fate, the circumference of the timing pulley is 360 mm, ergo, 1 mm=1* of timing. Skip trying to use an inch/foot tape measure and find metric tape that you can wrap around the pulley. Makes life soooo much simpler. Iirc, Yaw recommends a 24/16* advance at 3-4k rpm, which equates to an 8* split, not 10*, which is what most all rotarys have stock.

If you want accuracy, RB sells a replacement timing pulley that has much better marking.

Ok, my target boost will be 7 psi running 10* advance LEADING and TDC TRAILING (locked dizzy). I will be running a 72gph 6psi fuel pump through a summit canister filter to a 465cfm holley carb. exhaust will be 2.5" through inline and tailpipe magnaflow mufflers.

Any recommendations on fuel grade? 87, 89, 92?

I know this is not a rotor motor bt it is a draw through setup. I can say from experince that the intake charge is ICE COLD on a cold start up. I am in Midland GA about miffle of the state and you could not touch the intake between the carb and Turbo and this is even after drivinig it for a while... Here is a pic of my turbo beetle.. Made 471 rwhp when it broke the right rear axle in a 3rd gear dyno pull at 5500 rpms.. Could have made 500.. And as far as putting an Intercooler on a draw through... No way in hell I would do that.. It is a bomb waiting to explode with fuel sitting there.

http://i17.photobucket.com/albums/b9...06004Large.jpg

dont listen to Scott about timing he has no clue on a turbo motor. Although he will say he does just listen to turbo people.

No shit 24* btdc = blown up car if you're turbo

lock it at 10 degrees total advance and your all good
p.s. that bug is sick!!!

More pics of the bug twisted one!

http://i17.photobucket.com/albums/b9...06002Large.jpg

http://i17.photobucket.com/albums/b9...06003Large.jpg

wicked bug. What year is it? That car would look awesome with a 13rew stuffed in it.

WTB Used Wideband
 

Hey guys.. I've realized if im gonna try to push anything past 6-7psi, it would be best if I was running a wideband AFR gauge.

Does anyone maybe have a used one they would sell? If so, please PM me with pics and info. Thanks

If I do get my hands on a wideband... seems installing about 3 feet behind turbo is the norm. Any installation suggestions?

If you're a DIY type, you may want to check this out:
http://www.14point7.com/JAW/JAW.htm

I bought a kit from there, but I haven't gotten around to assembling it yet. Seems those who've used it have mostly good things to say about it.

well, the idea of spending ANOTHER $300+ for a guage is leaving a sour taste in my mouth as I already have a narrowband afr gauge laying around.

I know a wideband afr will burn up if to hot... thus the 2-3' mounting after the turbo.

But, I remember reading a narrowband NEEDS heat. Where is the best place to mount a narrowband sensor? Just a few inches behind the turbo?

Any recommendations on narrowband sensor itself?

Thanks guys

no more than 14" from the turbo downpipe. also make sure to mount the sensor on the top side of the pipe. oh and $300 is much cheaper than a blown motor !

this is gonna be the shortest lived turbo ever. Spend the money or dont do it at all.

yeah... buying a wideband RIGHT now.

prob gonna go with the AEM for the "needle" and digital readout... cough and price cough

Any1 have bad things to say about the AEM Wideband UEGO Controller Air/Fuel Ratio Gauges P/N AEM 30-4100

http://store.summitracing.com/partde...5&autoview=sku

Mine works like a dream

The AEM is good, i am using it now

thats the best price for a quality unit, get it!

Widebands are great for WOT tuning, but they don't react to spikes like a narrow band will. Like in my application I used to get a lean spike on cruise and the wideband doesn't see it at all, but the narrow band does. I run the atuometer procomp ultralight wideband and narrowband.

I believe a seller on ebay sells the UEGO for $205 shipped.

I've got a suggestion or 2! Nice car BTW....

Anyway I don't agree with only 10* of advance for starters..... I also don't agree with trailing spark on turbo/N20 applications.... Or disabling the vac advance....But hey that’s just me.

I think 10* is working for everyone because they are splitting there combustion cycle time between the 2 (L&T) IGN phases. This does seems to work ok… It’s just not as efficient as one big bang IMO. Also this means that as your cruising your timing is at 10* all the time.... This results in crappy MPG and drivability. Why not make it work more like it should?

Heres what I'd do... ;)

"T" 2 new leads from the wires powering the leading coil. Remove the orig. wires powering your trailing coil. They aren't used anymore,set them aside. Connect the T'd wires from the leading coil to the secondary coil. Doing this will disable the trailing spark and gives you one simple timing number.

Set base timing to 15*. (I like around 18*, see meth injection below)

Then install 3 or so 1-way aquarium check valve bleeders inline with vac advance on the distrib. This will allow vacc and not allow boost into the advance diaphragm. So during idle and cruise conditions you will have your timing advance. As you go into boost all the press/vac will be lost out the check valves,bringing you back to your base 15* timing.

Similar to this pic. It's cheap (under $10) and works very well....

http://www.gotrice.com/turbopics/temp006.jpg

Then instead of an IC I'd run a simple DIY methanol kit. This way instead of farting with carb. jets all the time, you can just adjust the amount of methanol you spray. It will cool the charge and fight off detonation at the same time. You can easily run 18* total timing and 10lbs of boost w/ the methanol injection setup.

All my suggestions are cheap and easy.... and will make a night and day difference on the way the car performs.

That little t-25 is gonna spool up REALLY fast! :lol: IMO a t-25 is too small of a turbo. It will choke the exhaust pulses. Ever notice how huge a stock TII turbo is for a 1.3 litre? I suggest a .63 rear housing and a 50 trim turbo of some sort. Stock grand national turbos are close to perfect. Also TII turbos work very well.



Good luck!


Bring on the flamin' :lol:

I can see how the one way check valve might work... That is IF i wasnt using a drawthrough setup... I would have to install something on the pressure side for that to work. Although... Setting leading and trailing to fire together sounds like an idea. Has anyone tried this success?

turbo info
 

So I cleaned up the turbo and got some part numbers off it, but, I'm finding it fairly difficult to find information on them. I've searched this forum and google.

It's an Ishikawajima-Harima Heavy Industry RHB6, serial # B6017759, spec V C 8. On the exhaust housing I can make out:
...... PZ
20.. -R
(the periods are just for spacing to show arrangement of letters/numbers)

The carb is a Holley list - 8007 (with 1113 under that). I think thats a 390cfm carb. The vac secondary pot is disconnected and linkage modified to work as mech secondaries.

From what little I've found, it appears to be similar to a Hitachi IHI-T3 or IHI-RHB6 T3 turbo. Its looking like it will reach max boost fairly quickly.

Any experiences with these turbos?

Anyone know where to find some info on it?

Thanks Guys

OK... here are some pics of my project I will be starting tomorrow.

Dude myself and others have been doing this for awhile. 10 is the safest bet. Don't fuck this dudes engine with your lack of turbo carb setup knowledge.

hmmm... wastegate ISSUES!!!
 

Started by tearing into turbo to make sure everything turns/moves freely.
I found my exhaust/internal wastegate was almost seized. The vacuum pot moves freely with plenty of closing force. I removed the wastegate valve portion from the turbo and soaked it liberally with WD40.. see below.

I can get the valve to move, but, it's pretty stiff. I put in back on the turbo, connected the wastegate linkage, manually opened the valve and it wont close all the way or move much at all. GAH!!!!!

Looks like tearing apart this valve will be near impossible as valve/flap is welded to shaft and set pin for shaft has been center-punched to lock it into position.

Im looking for suggestions.

I would weld the valve closed, and run a tial 38mm valve with a 10 psi spring.. You could do a 15 psi spring and put a boost controller on it...

For a simple setup (which is what your doing) Just keep it simple. Get yourself some JB blaster and soak it in that for a while (day or so) and keep working it. It should eventually free up. I'd get a torch or heat gun and get it nice and hot while working it. Then if possible get a small container and let the whole assy. set in penetrating fluid. (JB blaster)

Worst case you can tap the rod out and install new bushings.

Your incorrect. That's all there is to it. Anyone with even a little common sense would see that.

But I may be incorrect. Me an every auto manufacturer since the 1940's that has found adjusting there timing nets better MPG and performance. Turbo and NA cars alike.

Leaving timing set at 10* is moronic. It's 1940's technology. But I'm glad there are still some old school tuners out there. I like to whoop up on them... ;)

any turbo setup, even the new fuel injected ones have an ignition curve under boost that retards timing -not advance. timing advance under boost= blown motor.
since he has a distributor unmodified it will advance up to 30 degrees . this is ok for n/a but death for a boosted application. lock the dist. set it at 10 and be done with it. the guru taught me as with a few others chiming in and you guys know who im talking abour cough 680 cough :)
meth injection is great idea for draw thru since you cant intercool it :)

Progress!!!
 

OK... I was able to free up the swing valve for the wastegate.... what a pain in the a$$.
I ended up having to soak it in WD40 for several hours while almost constantly working the swing arm (Initial efforts actually required a hammer or long wrench just to move the swing arm). I also heated it up with a torch several times to try and free it a bit. My initial messing around with it bent the shaft of the valve a bit, but, was easily fixed. She opens and closes quite nicely now.

I didn't get that all put together until around 5pm today, but, still managed to get the exhaust manifold, vacuum side and pressure side intake manifolds and the turbo itself mounted today. Pics below.

Tomorrow I plan on plumbing in the oil feed line and oil return line, putting carb on, installing the boost gauge and fire her up... once I'm confident it runs ok I will lock the dizzy (set leading to 10* and trailing to TDC with vacuum pots disconnected), swap in my new fuel pump and filter, fab up the downpipe and connect it to my existing exhaust and install my wideband.... sigh.. than take her for a drive (conservatively as it still have 3/4 a tank of regular gas).

Wish me luck.

I've recently been PMing someone who is reminding me the original CarTech installation instructions say "...Ignition timing should be set 2degrees retarded on the leading and trailing."
There is nothing about disconnecting the vacuum lines or locking the dizzy.
I just want to make it clear this is a DRAWTHROUGH setup... the carb will ALWAYS have vacuum, even when i'm running 17psi boost (just before the engine blows.. lol.. I will NOT be boosting that much).
Most of the AWESOME advice people are giving me seems to be coming from peeps with BLOWTHROUGH setups. LOL, just wants to make that clear.

I disagree....

Yes as said, he should remove the springs on the fly weights. So as soon as the car starts the fly weights will lock out at full max mech. adv.

Anyway all I'm saying is the more timing U have, without detonation, the more power U will make. Esp. with a low boost application. (like is being done here) 8lbs of boost @ 15* of timing is still conservative. But it will make more power than 10* of timing @ 8lbs. So why not run more timing?

Personally I run 25lbs through a t-68 @ 25* timing. This is all on 91 octane fuel with meth injection.


Keeping your timing locked @ 10* is a total waste. You lose max power and cruise MPG. Esp. when not running much boost.