Non-Sequential Turbo Conversion

Last updated: September 13, 2002

• Non-sequential How-to (Trev's Non-Sequential Conversion)
• Non-Sequential Simplification
• Non-Sequential Boost Control
• Wastegate Porting
• Non-Sequential Kit

Non-Sequential Conversion

• Why would I want to convert my sequential twin turbo over to a non-sequential twin turbo?
  • If your car is bone stock you probably do not want to convert it.
  • If you have replaced your pre-cat with a downpipe and your main cat with a mid pipe, the pre-spool timing of the stock system will be off due to faster turbo spool up.
  • If you are running an aftermarket boost controller it will most likely not be designed to also control the turbo pre-control gate which can and will quickly cause excessive wear to your transmission and drivetrain.
  • Add an aftermarket intake and a larger intercooler and the prespool timing problems will increase.
  • With the above mods you will need to enlarge your wastegate anyway which is trivial to do while the turbos are apart for the NS conversion.
• Some say there will be excessive turbo lag with a NS system...Is this true?
  • If the exhaust is otherwise bone stock, then yes there will be considerable turbo lag.
  • If the main cat is in place and the pre-cat is replaced with a downpipe, and the engine is *mildly* street ported, stock IC (or upgraded IC) and upgraded intake, stock cat back (or upgraded), the lag will not be a major concern except for the hard core Auto-X racer (who should have a fully open exhaust at this point anyway)
  • With a fully open exhaust it is not a concern.
  • With a fully open exhaust and an upgraded intake and IC it is even less of a concern than above.
• What are the major benefits besides correcting the pre-spool timing problems with an open exhaust
  • There will be considerably less vacuum lines to worry about, and you will no longer need the 2 black vacuum and pressure tanks which will provide larger paths for air to flow around the engine cooling it more and helping to prevent the baking of underhood vacuum lines and components.
  • A smooth consistant, predictable boost curve that will come on strong and stay there through redline unlike the stock 10-8-10 PSI mess. This smooth boost curve means you no longer have to worry about the transition point occuring during a corner (which could and sometimes does send the car into a tailspin)
  • Less restrictive exhaust path, which ultimately results in less backpressure being seen by the engine (IE more power, and less internal heat)
  • It will become trivial instead of impossible to troubleshoot problems with the turbo system (if you have any :)
• What are the drawbacks?
  • The dealer service department will not know how to work on the car with all the vacuum lines ripped out...wait they can't normally work on the stock system anyway :)
  • You will have to work on the car yourself due to the above reason...wait thats good because of the above reason.
  • Will knock you out of the showroom stock class (not a big concern if you are racing only for fun and not trying to go for nationals)
  • Excessive, but livable turbo lag when you are driving the car that one day a year with the stock exhaust system on it :)
• Okay, shut up and tell me how to perform the NS conversion
  • Basic Parts List
  • Disassembly
  • More information from an email I sent to help someone with some extra questions
• Leave me alone, I like troubleshooting all the boost problems I have had with the car since I bought it new.
  • Go Back

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Parts:

Disassembly:

email:

You will *need* to open up your wastegate from the on paper 1" diameter to
1.24". Use a mill to do this, don't waste your time with a die grinder as
some people who obviously have more time on their hands than common sense,
or money to pay a machinist have done :)

The mill has the added benefit of allowing you to align the hole with the
flapper, which is something the stock hole is not. (IE off center some
whgich is not a problem with a 1" hole, but 1.24" would be)

The Turbo Pre-control gate should be welded open. The weld goes at the
base of the outside control arm, and should be welded good, not just
tacked. (preferably TIG welded, but a good wire feed is acceptable for
this)

The turbo control gate in the manifold has got to be removed and the hole
tapped for pipe threads, and a cast iron pipe plug installed.

To remove, take a cut off wheel, or a 4" disc grinder and cut the control
arm off at the base, then grind the welds off and remove the outside
washer, then from the inside tap out the sleave the flapper shaft rides
in, then the flapper valve and shaft will come out from the inside.
DO not even think about welding this one...do not leave it in there...it
absolutely has to come out!

The solenoid valves will all stay in place. If you have a CA car leave the
EGR vacuum line attached, or run a new one. All other lines should be
removed.

The MOP lines should be saved, and the metal mass of metal lines which
they connected to should be removed, and seperated. You want to keep the T
arrangment that the MOP org. connected into as its perfect for this.
Connect the MOP nozzles to the T (just like stock) and tie-wrap the T to
the solenoid valves. Run a new vacuum line from the T down to the vacuum
orfice coming off the front turbos inlet elbow (there are 2 orfices
there...one for vacuum for the vent on the oil filler and one for the MOP
vacuum)

The only other vacuum line you will need is for the fuel pressure
regulator. Take a line that has a molded U shape in the end, and run it
from the fuel pressure regulator, around the inside of the lower intake
manifold, and connect it to the Vacuum nipple which is facing rearward at
an angle.

Vacuum cap all the other vacuum nipples, and you may even want to remove
and cap off the PCV valve as its not needed (95 RX7 comes stock with this
capped off on both ends where it used to connect which I was already
doing before I saw a 95 rx7 :)

The wastegate control actuator itself should be connected to an
aftermarket boost controller, or a manual bleed valve (like one the paint
guns use)

The butterfly in the turbo Y pipe has to come out, and a blocking plate
installed in its place. You should also remove the butterflies from the
upper intake manifold as they will not work with your new arrangment.

Both black canisters (vaccum and pressure chambers) should be tossed, as
well as the large turbo control actuator, and turbo precontrol.


Blocking Plates For Non-Sequential Conversions










These are 1/8" thick band saw cut aluminum. Just trace
the outside of the gaskets, then cut. The same for the gasket
material...that was made from the make your own gasket sheets you can buy
at any auto parts store.

One thing I was not clear on...leave the solenoids in place and electricly
connected. The same goes for the large solenoid array bolted to the back
side of the lower intake manifold...I make a large blocking plate for it,
and leave it in place (you will have to remove the one way circular valve,
to get the blocking plate in there)

All those sensors and solenoids stay connected electrically as well, but
all lose their vacuum lines.

The MAP sensor of course keeps its line.

The two Blow off valves should have their vacuum lines teed together and
tapped into a vacuum nipple on the passenger side of the upper intake
manifold. You now will have 2 BOVs working together instead of the 1 +
somthing alltogether different in function at least.

If you run into any questions feel free to email...just use common sense,
and if in doubt, remove it, and block off where it was...if its not
electrically connected, then its usually not needed.

Trev
FTL Racing

0000 - 2500 rpm, vacuum
2500 - 4000 rpm, boost building
4000 - 4500 rpm, 14 psi boost
4500 - 7500 rpm, about 12.5 psi boost

If anyone is interested I took some pix. I haven't added any information other than the pix themselves but will do so tomorrow night which will include; bolt sizes, welding, porting, basically what goes where. http://members.xoom.com/diepat_rx7/rx7/non_seq/turbo/Page.html

________________

Date: Wed, 14 Mar 2001 13:51:58 -0600
From: "Westbrook, Chuck E." (CWestbrook@tmh.tmc.edu)

For the experienced FD owner/mechanic here is some details of my conversion last year. A well done conversion is the key to success!

CONVERSION FROM SEQ TO NON-SEQ TURBOS, NON DETAILD

MINIMUM MODS REQUIRED FOR FAIR LOW END RESPONCE:

• Cold air induction.
• IC upgrade.
• Down pipe.
• High flow cat.
• Cat back straight through design exhaust.
• Upgraded ECU or Apexi PFC.

MODS THAT FURTHER INCREASE RESPONCE:

• Mid pipe.
• Balanced turbos with clipped turbine wheels.
• Lighter flywheel.
• Exhaust and/or intake porting.
• Port matching of intake and exhaust systems.
• Under drive pulleys.

CHANGES:

• Remove turbo assembly and exhaust manifold.
• You will no longer need the turbo control and precontrol actuators. Remove their control hoses from the metal control pipe group. Cap the ends of the no longer used pipes.
• Cut off the turbo control gate arm and remove the sleeve and gate from the exhaust manifold. You tap the resulting hole for 3/8" pipe thread, I think. Then inert a 3/8" "cast iron" pipe plug. Do not use a steel plug!
• Port match the manifold to the exhaust ports, and to the turbo assembly #1 turbo inlet. The #2 turbo inlet is very large due to room for the now removed turbo control gate. There isn't enough metal there to totally widen the #2 port in the turbo assembly. Instead round off the 90^ edges by grounding them back about 1/8".
• Have the precontrol gate control arm tack welded in the open position.
• Now is a good time to remove the turbo cartridges from the assembly and have them rebuilt/balanced and clipped. Also time for have the WG opened up.
• Remove the charge control actuator from the rear half of the "Y" pipe assembly and cover the opening with a cover plate. Place a cap over the charge relief valve pipe and secure with a clamp. Cap off the two small control pipes.
• Now is a good time to port match the ends of the "Y" pipe to the turbo's compressor outlets. Again use their metal gaskets as templates. Cap off the small pipe on the "Y" pipe outlet, it was for the pressure tank.
• The three now unused 3mm control hoses from the intake manifold can be pulled off.
• Since you no longer need the pressure and vacuum tanks, remove these.
• You can also simplify the control solenoid rack and hoses going to the intake extension as you wish.
• If you have the time, remove the intake extension and intake manifold now and port match the two pieces to each other using the metal gasket as the template.
• Unfortunately you can't port the intake and exhaust, or port match the intake manifold to the block now, will have to wait for your engine rebuild.
• If you are even more fanatical like me, you can also work on the IC and it's pipes, and the throttle body to improve air flow through them.

With all of the above mods except MP and intake porting, and still running the air pump; low end response is better than a stock FD except in 4th or 5th between 2500 and 3000 rpms. Using the gears properly, nothing is lost, and much is gained. In day to day driving in Houston traffic, I normally do not go over 3000 rpm in 1st through 3rd and drivability does not suffer.

________________

Date: Wed, 14 Mar 2001 16:04:21 -0500
From: "Wade Lanham" (wadelanham@hotmail.com)

Excellent information! I would like to add a few comments, though I am certainly not a non-sequential expert.

All the unused nipples on the Ypipe and upper intake manifold should probably be removed and Tig welded over. It's a shame to remove all those hoses and then just put a cap over the nipples, since they can break/leak too. Some of the nipples (all?) are press-fit into the aluminum, so they will need cut/drilled or pulled out before Tig welding over the holes.

Also, more importantly, it should be mentioned that it is usual for people who have made this conversion who have no cats to have BOOST CREEP, even with a ported wastegate! This is highly important, since boost creep can be a bigger problem than a failing sequential system!

Most of these people end up installing RESTRICTIVE exhausts to keep the boost under control. All that work to improve efficiency is wasted if this is the case. This is probably the biggest reason I still have the sequential system.

Non-Sequential Boost Control

For non-sequential, I would think the Hallman controller would work well.

Good reports from 10 sec DSM users. Contact Marc Hallman, at website below. It should provide quicker spool up than the long hose method, that does progressively open a double springed WG. Yes, simple relief valve, but he has got it sized to work right.

(Your xtra parallel spring idea is much better than excessively increasing preload on existing spring...resulting in lost motion at the flapper valve)

Non-Sequential Simplification

I am in the process of converting to non-sequential with the help of Jim, Justin, and Trev. I slapped up a quick page with 10 pictures. This is part 1, where everything necessary is off the car (and on my garage floor). I hope these pictures are interesting to some of you who maybe haven't seen the turbos and exhaust manifold before.

________________

Date: Thu, 13 Jan 2000 11:14:20 -0800 (PST) From: Mark Valskis (mvalskis@yahoo.com) Subject: Re:(rx7)[3]sequential simplification? (emissions elimination)

> I have reason to believe the sequential control system can be
> simplified, but still function the same as far as boost pattern.
> Do any of the control system experts on this list know of a way to
> remove hoses and solenoids that aren't absolutely necessary for the
> operation of the sequential system?

Sequential simplification isn't really a valid title, since you are not talking about affecting any of the sequential control hardware.

That said, at least half of the solenoids and a lot of the rat's nest is due to emissions controls. If you don't have to deal with emissions at all, you could get rid of these things and reduce the bundle and clutter substantially. If you are still running the factory ECU, you would have to wire in resistors to the wires that used to connect to the solenoids so that the ECU didn't trigger an error code. The list of solenoids which control the emissions are as follows:

Purge Control Solenoid
Relief1 Solenoid
Relief2 Solenoid
Port Air Bypass Solenoid
Split Air Bypass Solenoid
Switching Solenoid

Additionally, you could disable the accelerated warmup system and eliminate the AWS Solenoid.

You would be left with:

Idle Speed Control Solenoid
Pressure Regulator Control Solenoid
Turbo Pre-Control Solenoid
Turbo Control Solenoid
Charge Relief Solenoid
Charge Control Solenoid
Wastegate Control Solenoid

_______________

From: Wade Lanham (walanham@mountaineergas.com)
Date: May 10, 2000

See the following diagram:

The parts are in their approximate position on my car.

See the following photos:

I made this change because I wanted to keep the sequential system for now, but I wanted the car to be easier to work on and look cleaner under the hood. I envy the non-sequential look. :)

"Thanks" to Mark Valskis and Derek Vanditmars for answering questions, and Mike Putnam for putting together the "turbo control systems ONLY" colored diagram.

The ways I succeeded:

1. The system is very simple now - there are few enough hoses and solenoids that I know where they should connecte and what they do.
   
   
2. The engine looks marginally cleaner fully assembled, and much cleaner with the upper manifold removed (where the lack of solenoids/hoses really shows).
   
   
3. Almost every hose is easy to see and reach without removing ANY parts. I placed the solenoids and most hoses just behind the alternator but in front of the upper manifold. If a hose does pop off, it shouldn't be hard to fix.
   
   
4. I have a box that weights about 15 lbs that has nothing but stock "junk" hoses, tubes, valves, etc.

The ways I failed:

1. The engine looks only marginally cleaner when fully assembled.
   
   
2. There are still approximately 25 vacuum hoses.
   
   
3. My car runs poorly when cold (I think this is because of the fast idle cam removal - I'll know for certain soon).

Notes:

1. In the diagram, I show nothing for the fuel pressure regulator. I did some fuel system work at the same time as the vacuum system which included an aftermarket fuel pressure regulator that I attached to the nipple on the bottom of the lower intake manifold (same source location as stock but with only one hose.) You MUST leave the stock system intact OR add an aftermarket pressure regulator of some kind. For those not modifying their fuel system at this time, be SURE to have the FPR solenoid and lines attached well and correctly (failure of any of these parts could easily cause engine failure).
   
   
2. I left the colors the same as Mike Putnam's (?) colored flow diagram and system diagram. His diagrams were essential for me to make these changes to my system successfully. I recommend printing both of his diagrams and mine if you plan to perform this modification.
   
   
3. For the Charge Control Solenoid and Charge Relief Solenoid lines that T, and the oil metering vacuum line T, I used some plastic Ts from the local auto parts store. For the Vacuum Chamber connections I used 5-way that has a nipple on each end and three nipples coming off the side. I removed all other metal tubes and Ts except for the tubes running down to the intake elbow and the turbo actuators (it is left in the diagram) because it seemed like removing these would make the area cluttered with silicon hose instead.
   
   
4. I removed all the metal hoses for fuel/coolant. All the coolant lines were replaced with one that runs from the back of the block to the filler neck in a straight shot. All the fuel lines were removed because I tapped the injector rails and used braided stainless. Most people will probably be leaving all of these fuel and coolant lines stock.
   
   
5. I removed all of the solenoid "Rack." The rack was replaced with a small piece of aluminum that now holds the CC, CR, and the TC actuator (that is normally on the ACV). The new AL rack is attached to the upper tab on the coil box. There are two of these - I think they might have been attached to the original rack (?). The Pressure chamber is mounted upside down where the ACV used to be. You could put it wherever you want. The other TC black solenoid rack valve is located in between the new rack and the lower intake manifold in approximately the same position as in the diagram.
   
   
6. I removed the ACV, EGR, DT, AWS, and Fast Idle cam. I probably should have left the fast idle cam, because my car now runs like crap when it is cold. These parts were replaced with blockoff plates and any solenoids that would cause error codes were replaced with the appropriate resistors attached to connectors that would slide into the original harness (I didn't really want to cut the stock harness up at this point). You can get the resistance of the solenoids from the workshop manual. If anything, go a little on the high side.
   
   
7. I left the uncolored hose (in my diagram) on my car. I meant to remove it, but forgot until it was inconvenient.
   
   
8. I left the fuel evaporative system intact at this time, sans some of the unnecessary plumbling.
   
   
9. I rewrapped a lot of the main harness because the shrink wrap shattered when I moved the harness around.
   
   
10. I removed the nipple for the PVC from the manifold (capped the filler neck nipple), and the double throttle plates and related hardware. I tapped both manifold holes and plugged them.
    
    
11. The orange line that seems to go to nowhere goes to the upper intake manifold (it should be obvious, just thought I'd mention it before someone asked).
    
    
12. I used one of the nipples on the back of the intake manifold for my boost gauge.

I think that's it for now. As I think of more, I'll make adjustments to the diagram and this document. If you have any suggestions or question, just leave me a message. I'm not very busy this week at work (if you couldn't tell already from the length of this message).

Non-Sequential Kit

Trey Cobb                               trey@rx-7.com
Rotary Performance - Online!    http://www.rx-7.com
Garland, TX                             972-530-3335