GT35+3500

[timg]

I don't have a flex in my Y, but do in my down pipe. No problems so far.

I agree that boost and WBO2 sensors are the first sensors to consider. I wouldn't waste money on a narrowband O2, especially since wideband O2 sensors with displays are now under $200. A wideband O2 should be pre-cat but at the bottom of the down pipe. I wouldn't worry about EGT.

With the vacuum ports, it depends on what they go to. Many may be much better off with check valves or run to their original source than plugged off.

Tim

[ericjon262]

I started thinking about it, and the only vacuum, port I can think of that isn't a sensor is my brake booster, which I think I will plumb to a canister with a check valve.

I'll have to see if a buddy has a copy of maximum boost I can borrow.

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My brake booster doesn't have a check valve. If I try to use brakes under boost, there's no assist, but as long as I'm not WOT and trying to brake, it's not an issue.

Tim

[ericjon262]

I'm going to go obd2 for engine management, where should I put my MAF? pre or post turbo?

[Z26-T]

For the brake booster, most systems come stock with a check valve in it. That is so there is always a reserve inside the booster, which increases the life of the diaphragm. It's also so the booster doesn't empty when the engine is shut off. The booster should also retain enough reserve for 3 assisted brakes before it's depleted.

Think about the question. The computer needs to know what's going into the engine.. So would it be better for it to know what's going into the turbo or the throttle body?

[3400-95-Modified]

things to remember on maf placement is how with the compressed air temp will affect the reading, as well as if pre you will have a BOV and vent to atmosphere so you will get pops on shifts from it registering air going in but never making it to the engine so it will be a little extra rich.

Blow through MAF's are not a bad idea, but I think they are a bit more difficult to scale... I've never messed with one like that and my legacy is a suck through so with my 50/50 BOV I will get some pops on shifts if I'm a bit aggressive with it, but overall its not bad.

My brake booster doesn't have a check valve. If I try to use brakes under boost, there's no assist, but as long as I'm not WOT and trying to brake, it's not an issue.

Tim

A brake booster has a check valve from the factory stock for the same reason, a N/A engine you loose Vac at WOT so they put a check valve on it so there is always vac in the booster to assist you. Why would you remove that?

[ericjon262]

I think I will go ahead and put the maf right ahead of the TB, that way it will read exactly whats going into the engine. would it be a bad idea to run my oil feed through a oil cooler pre turbo? also, I got my turbo in today!

[timg]

Why cool it pre turbo? If you run an oil cooler, let it benefit the entire engine.

I didn't remove any valves built into the brake booster, but I didn't add any either.

I've had my MAF pre-turbo and post turbo. Pre-turbo meant huge fireballs out of exhaust every shift with a loud boom to go with. It also meant occasional stalls when the engine ran so rich it killed itself after the BOV released pressure. MAF post BOV has been very stable and easy to tune without any of the drivability problems I had with it pre-turbo.

Tim

[ericjon262]

well, I'm not too worried about how easy/hard it is to tune I'm outsourcing that. I re-thought the oil cooler thought... I don't know what I was thinking...

I'll try to post a few update pics soon!

[TGP37]

A fiero, yeah that will pull freaking hard man with that much boost. My heavy ass 96 GP with 8psi is a beast. But a Fiero 5-speed with 15psi.....lol. gonna be nice.


You can have the BOV after the MAF. But the MAF would need to be pre-turbo and the BOV redirects the discharge back into the intake between the turbo and the MAF. This will provide the best respool after shifting. As the discharged air circulates and keeps the turbo spooled up a bit longer. Though, I haven't actually worked that setup yet so I could be misinformed.

[ericjon262]

A fiero, yeah that will pull freaking hard man with that much boost. My heavy ass 96 GP with 8psi is a beast. But a Fiero 5-speed with 15psi.....lol. gonna be nice.


You can have the BOV after the MAF. But the MAF would need to be pre-turbo and the BOV redirects the discharge back into the intake between the turbo and the MAF. This will provide the best respool after shifting. As the discharged air circulates and keeps the turbo spooled up a bit longer. Though, I haven't actually worked that setup yet so I could be misinformed.

I'm going to run a 5 wire MAF, so it would be best to have the MAF close to the TB so the IAT reading is more accurate.

[95SleeperAcheiva]

stock lower end can handle 15-18 lbs of boost?

I got a turbo sitting here for my DOHC and I was worring about pushing 8.

[3400-95-Modified]

A fiero, yeah that will pull freaking hard man with that much boost. My heavy ass 96 GP with 8psi is a beast. But a Fiero 5-speed with 15psi.....lol. gonna be nice.


You can have the BOV after the MAF. But the MAF would need to be pre-turbo and the BOV redirects the discharge back into the intake between the turbo and the MAF. This will provide the best respool after shifting. As the discharged air circulates and keeps the turbo spooled up a bit longer. Though, I haven't actually worked that setup yet so I could be misinformed.

The BOV on my Legacy is after the MAF on my TMIC, and the MAF is pre turbo, Stock this car had a 100% recirc valve that would release the excess pressure back into the intake post MAF sensor, so yes that method works just fine, but way too many people out there want that BOV sound so in that case yes if your running 100% VTA then you will get fireballs and backfires and rich conditions on shifts. Thats why I have mine setup at 50/50, you still get a decent amount of BOV sound, but most of the air is also recirculated so you get less of a pop or fireball.

My Legacy's MAF is also a 5-wire so the IAT is pre Intercooler and it runs fine, many keep it that way and don't convert to a blown through MAF, just a fyi.

A lot of the discussion that I see online on running a draw through vs blow through is mostly due to turbulence, they say there is much more after the turbo than before it. However I do not know how much a FMIC and piping will change that story if your Maf is almost the last thing on the system before the TB.

[bearbear3_4]

I'm going to run a 5 wire MAF, so it would be best to have the MAF close to the TB so the IAT reading is more accurate.

On my 3900 I run the stock 5 wire maf between the BOV and TB that way it only reads the air that will be entering the engine.

[ericjon262]

stock lower end can handle 15-18 lbs of boost?

I got a turbo sitting here for my DOHC and I was worring about pushing 8.

maybe, we'll find out!