Ok, i've noticed a lot of TII people don't have ECUs or upgraded turbos. Ideally speaking, and the general consensus, is not to run more than 10-12 on the factory turbo. So how to limit the flow going into the engine, so that the turbo never sees more than 10-12 psi. Setup something like this:

Full exhaust or DP, Hiflo cat, catback
Intake
FCD (debateable, not in this thread though please! )
Gauges out the wawa

Could it be possible by using a smaller piece of pipe in the TID or using a 90 degree bend or two, to keep the boost levels down? Crazy q I know...but i've been curious for some time now.


Joe

 

Keep boost down ? I'm still trying to bring it up...

 

Just an idea to keep the boost from spiking to 15 psi and killing something ....get the DP and you'll see it go up .

 

pop off valve!

 

But that'll just save the motor, it'd still kill the turbo.

 

^

 

i played with that with mine.
the intake duct has a big impact on the power curve.
a small diameter duct will give you tons of low end and throttle response, but you lose a bunch off the top.
a big duct will give you more top but it has less response. i only played with a 2" and a 3" duct i think 2.5 would give a good mix of both.
another thing to do to keep boost down is to leave the stock airbox and some sort of main cat in the car

mike

 

how about porting the wastegate? would it work on the s5 wastegate too? cause i heard the 89-91 wastegates are electronically controlled or something.

 

Erik has his S5 wastegate ported, so it can be done. I'm trying to think of a way to hehe clog the intake a bit to keep boost down...

 

why don't you try a manual boost controller,,buy one made out of brass fitting off of ebay for $12 and set it and forget it,,if the boost goes up the waste gate comes open,,pretty simple

 

I'm getting real sick of saying this:
NO BOOST CONTROLLER CAN LOWER BOOST!
It can only raise it!
Dunno about that. The TID I installed on my 12AT resulted in much quicker boosting (and hence more mid-range torque) and more top-end pull. How would a restiction in front of the turbo aid response?

 

i think it had something to do with the velocity of the air in the tube. i also didnt use the the stock tube and a 3". i have a 3" pipe and a 2" pipe.

mike

 

Velocity is really only an issue with intake runners and exhausts, not turbo inlets. Some compressor housings flare out to 4" for the TID connection!

 

i have to disagree with you about the boost controller,,,it works on a check ball and spring you could set it to release at 1 psi if you wanted by removing some of the tension on the spring thus letting the waste gate open much earlier

 

You have no clue how a turbocharger wastegate system works or how that boost controller works.&nbsp You need to do your homework before you start claiming things that are utterly false; it just makes you look really stupid.



-Ted

 

So Ted, now that we have your attention

How would you limit boost on a near stock setup with full exhaust. Could you do it via the intake?

 

damn .....such harsh words RETED !

 

The two easiest and most practical methods I've seen are...
1) Run a very small air filter cone, if you're running a cone filter.&nbsp I used to run a dinky cone filter (K&N part number RU-3120) that kept my boost down to 10psi with a full 3" exhaust; after throwing on an R.S. Akimoto rip-off FunnelRamII, my boost went up to 12psi.
2) I knew a guy who blew his 130k motor after installing the RB full 3" exhaust.&nbsp He rebuilt his motor and installed a 2" restrictor plate in the exhaust pipe between the downpipe and the pre-silencer.&nbsp He got consistent 10psi of boost afterwards.



-Ted

 

If you want to keep the boost down, don't put the 3" exhaust on.

as for the boost controller, if it can raise boost,it can lower it (back to where you'd be without the controller)

sorry... play on words.

With a boost controller on a stock TII, how high can you turn it up? I've got one on my near stock TII and I closed it all the way. I see boost earlier on, even the top end of first, but I still don't see any higher boost. It seems to just control the speed my turbo spools up.

 

Why don't you just leave the stock TID in place? It's quite a good restictor, and it's free! Any way you limit boost will hurt power, but there's no point in actually spending money to do it!

 

explain it then,,this is how it works on my friends awd turbo talon,,is there something about the rx7 that is special

 

the wastegate is much smaller on the FC so with those mods you are out-flowing the wastegate and boost is going to climb anyway.

 

I don’t know what you do know, so I’ll assume you know nothing (don’t be offended).
Boost pressure from the outlet of the turbo is applied to a diaphragm in the wastegate actuator. When this pressure overcomes the force of the spring behind this diaphragm, the actuator opens the wastegate, bypassing exhaust gases around the turbine instead of through it, thereby maintaining a constant compressor wheel speed and hence constant boost.
If you lower the pressure signal sent to the wastegate actuator, the actuator will open the wastegate later, resulting in higher boost. A boost controller does this by bleeding some of the pressure out of the wastegate actuator line. The same thing can also be achieved with an inline pressure reducing valve.
The only way to reduce the boost level would be to increase the pressure in the wastegate actuator line causing the wastegate to open earlier. Where are you going to get more pressure than the turbo is producing?
There is nothing special about the RX-7's turbo. I just think you may have misunderstood whatever your mate did to his Talon.

 

No, its just your friend's Talon has a crappy turbo...


-Ted

 

as I stand, I'm hitting about 9 psi with the RB exhaust and stock intake box and stock TID. I hit 11 with a k&N cone and stock TID.

I think this summer I'm going to add a 3" cat which I'm hoping will lower it a few psi. Then I can add a bigger TID and cone filter and still only creep to 10. (hopefully) I figure I'd have more power and better spool with a cat, k&N, and tid then with no cat and stock intake. but the boost creep would be about the same. plus with the cat I'd be legal

we'll see what happens, the best way would be to take the turbo off and port it though... but that takes more work