dwb87

iTrader: (22)

I removed my emissions a while back and was wondering - since I removed all of those solenoids (sp?), including the twin scroll solenoid, then should I remove that actuator down by the exhaust manifold? or what do I do with that??

NZConvertible

Connect it back so it works and you have less turbo lag. Remove the solenoid valve with the green sticker and the little green and white check valve from the vac rack, and connect them back up using vac line as per the schematic on page 4B-53 of the FSM and the attached vac diagram. It's important to make sure the solenoid valve and check valve are oriented the correct way or it won't work. Verify it works by following the FSM check procedures.

HAILERS

Another picture. Jpg attached

Richter12x2

iTrader: (1)

Along the same lines - if you're using higher compression rotors, would it benefit you much to keep the twin scroll, or would it be better to remove the flap and let the higher compression rotors compensate for it?

The shorter question is, would it be worth the additional money and hassle to setup and install the twin-scroll system for a car that didn't have it, or would it be better just to remove it entirely and weld the hole on the manifold shut?

NZConvertible

What makes you think higher CR would have the same effect? Why not have the benefits of both? And if you already have it, what money and hassle is required?

Richter12x2

iTrader: (1)

I'm sure I'm wrong, but bear with me because I'm new to turbo'd cars in general. With that said, it is my understanding the object of the twin scroll system is to block off essentially half of the exhaust stream at low RPMs, which would cause the exhaust velocity to increase, so that the turbine spins up faster, getting you into boost faster, which would compensate for a lack of power down low due to lower compression rotors. By using higher compression (NA) rotors, theoretically your baseline hp would be roughly the same baseline hp as an NA Rx7. The higher compression increases the exhaust velocity which also gets you into boost faster. From what I hear, in a turbo NA, the boost comes on pretty early already compared to a stock TII.

From my original post, I asked if it was worth it for car that DIDN'T have it. I'm running a turbo'd NA, so I've got an NA harness, which doesn't provide for the twinscroll, I've piecemealed parts together, so I don't have a twinscroll solenoid and whatever it presumably mounts to, unless it's the side of the exhaust manifold, and my stock NA computer probably doesn't have a provision for activating the twinscroll solenoid. So additional cost would the be the twin scroll solenoid, rewiring the connector that Hailers mentioned, and a turbo computer.

If the exhaust is going to be open 98% of the time anyway, then it probably wouldn't be worth it to me to spend another $300 to get the twinscroll system working correctly. If I'm not going to use it at all, I need to make provisions to remove the flap completely from the manifold. If it IS worth adding later, then I'll need to find a way to wire it open while I collect the parts.

dwb87

iTrader: (22)

Alright, I forgot to add in... I am using an N/A harness. I DO have the twin scroll solenoid though. Which solenoid "plug" or whatever, from the N/A harness would I be able to use?? Can I just remove it? I mean I would like to have it because of what NZConvertible said.

Richter12x2

iTrader: (1)

I did a search on twin scroll removal, and one of the results on the first page had a bit from Hailers on what needed to be changed from an NA harness to a TII for the s4's. It was within the first 10 results, I think.

NZConvertible

This is true, but I doubt the compression increase is as effective as the twin-scroll system. Having both is obviously best.

You mentioned removing the system implying you already had it, and never mentioned you've turbo'd an NA. That should've been mentioned up front. We're not mind readers, so the more info you put in your posts, the better the answers will be that you get.

IMO you should already have a Turbo ECU, but all you need to activate the solenoid valve is an rpm switch. You can use one of your redundant vac rack solenoid valves, and just switch the little filter to the other end. It can be mounted anywhere/anyhow you want. You need a check valve which you also have from pulling the double-thorottle system. Then all you need is the actuator which should be easy to find by looking and/or posting in the For Sale section. The whole thing could be done very cheaply.

Nobody spends 98% of their street driving above 2700rpm, or even 90%. Nobody.

If you think less lag is worth the effort, then do it. If you don't, then don't.

Richter12x2

iTrader: (1)

Got it, I'm beginning to understand this a lot better now. I think part of our misunderstanding is that I kinda jumped in on someone else's thread - the original poster I think is talking about removing it from a car that has it - I was asking about adding it to a car that didn't. Didn't mean to make things confusing!

I guess I'll have to do some thinking on it - probably the easiest for me to do at this point in time is to wire it open, then I can add it later - it's going to be more difficult for me because I removed the emissions from my car, then later remade the wiring harness from scratch, and didn't run wires for the things I'd removed to make it cleaner, so I'd at least have to run new wires from one of the vacuum rack solenoids. All that stuff is still around, so it'd just be some more time. On the Turbo ECU, my eventual intent is to go standalone, so for now I've got a piggyback unit, a SAFC that I'll be tuning with my UEGO to keep everything under control. Sure I don't get the really cool timing retard, but I'll get that eventually when I go standalone. I'm not looking for crazy numbers - 250hp would be nice, and 276hp would be just awesome in my book.

dwb87

iTrader: (22)

I am somewhat confused on this whole ordeal. I would like to KEEP the twin-scroll system. I just don't have the twin-scroll solenoid plug on my harness because it's an N/A harness. I thought maybe you could use another solenoid plug for the twin-scroll solenoid...

Richter12x2

iTrader: (1)

Yes, hit the little searchy button and type in 'twin scroll removal' - one of the first handful of posts has a detailed post from Hailers telling what solenoid plug to use for your twin scroll, when you use an NA harness. I SO promise, it tells you exactly what you need to know.

HAILERS

Remember your non turbo engine had a ACV?? Say yes.

On the ACV there are two solenoids that screw into the ACV. Remember?????

Each solenoid had a *pigtail* harness as a part of the solenoid and it was about a foot long. On the end of that pigtail was a connector.

That connector attached to the main EM harness. The color of the two wires on the EM half of that plug are colored Black/White and the other is Blue with a Black stripe on it.

So, go look at your n/a harness and look in the area of the water filler neck area of the harness. You should find a two socket plug there with a Black/White wire and the Blue/Black wire in the sockets.

THAT plug will power your twin scroll solenoid. Where you locate that solenoid is your business. When I did my swap I used the twin scroll solenoid that came with the turbo engine. All I had to do is run two new wires from the plug I just described from the water filler neck area over to the Twin Scroll Solenoid and attach the two wires to the solenod. It matters not which wire goes on which blade of the solenoid

I don't know your story, but even if every solenoid is off the engine, you just go find a solenoid out of the trash and use it.

This is just about the ONLY change that needs to be made to a n/a harness in order to use the n/a harness on a turbo engine. It beats the living hell out of using a turbo EM harness on a n/a car. That is rock dumb if you can avoid that.

HAILERS

Attached is a jpg of a ACV and shows which of the two screw in solenoids is the Split air solenoid. This ACV is SIMILAR to the n/a one. It's a turbo ACV.

HAILERS

I'd suggest finding a solenoid that is useless. Say the EGR solenoid and using it as the Twin Scroll Solenoid. Just make or configure the new solenoid like the one in the attached jpg. That means the solenoids filter will be located near the electrical connector.

IF you find a solenoid with the filter not near the electrical connector.....just pull hard on the filter and it'll come off the solenoid. Now attach it to the metal nipple near the electrical connector.

A jpg is attached of a vacuum rack, a spare vacuum rack and showing how it looks in life. You run your two NEW wires mentioned in the thread above, to the electrical tangs on the solenoid.

Mankdrake 2661

iTrader: (8)

2700 RPM in 5th gear only gets you to 60mph. I drive the interstate everyday to and from work 70-75mph(somtimes 80 if I'm running late!). That's an hour more each day. So I'm cruising at 3200-3300RPM. BUT at that rpm you'll hit your boost pretty quick anyway. Especially with an N/A block.

dwb87

iTrader: (22)

HAILERS, thank you SOOO much. This helps me out a lot. I do have the twin-scroll solenoid that came with it, with the check valve. I know where the vacuum lines go and you pretty much finished the other part for me. Thanks again!

Richter12x2

iTrader: (1)

Like NZ said, it's probably helpful if it's no added trouble, so for now I'm just going to wire it open to get the car running, and keep my eyes open for someone local parting a TII out or one to pop up in a junkyard so I can get the parts to make the twinscroll fully functional again.

NZConvertible

I said street driving, as in driving around suburban streets, not speeding along highways. Constant high-speed is obviously irrelevant to the the discussion.