OVTune 3.5L Tacoma Supercharger and Twin Turbo Systems

No kidding! And more off road potential to, I don't have a Tacoma yes Meao but I did grab a 99 4runner, I already got weld yourself sliders and a lift kit waiting to be ordered, 4runner isnt even legal yet, gear heads cant leave nothing alone! TT kit for 99 4runner OV? Rofl

 

Can anyone provide a link to research on exhaust diameter? My internet searches have turned up nothing but general recommendations like "n inches is good for m horsepower" but no reference on where that information came from.

 

There isn't really a general rule... More so based off individual engine setups, back pressure, and what works best on that particular engine.

Having said that, I have ran 5in downpipe and exhaust on 5.9 Cummins engines, while running 2.5in downpipes and 3in exhaust on a 600hp/650tq twin turbo Audi V8, while running 4in on a 1000hp 4.6L 2 valve mustang. It really just depends.

Typically less back pressure on turbos is good, but that's not always due to running huge exhaust. Just look at Audi and BMW running turbos on V6s and V8s, most if not all come from the factory with 2.5in downpipes and exhaust. Hell I am almost 100% positive that ecoboost F150s are stock 2.5in, which is what I would stick with on a turbo Tacoma.

 

Biggest issue in most stock exhaust setups on FI engines is the down pipe. I’ve taken a few off and they’re always highly restrictive and sometimes have a giant bend / clamp / pinch of some sort to restrict flow. A lot of folks switch to straight (labeled as test) pipes, but a high flow is still plenty good as it takes all of the factory restrictions (and emissions) out of place.

NA engines need back pressure. When you install turbo on this, it won’t be an issue. Exhaust diameter will largely be how loud / annoying you want your truck to be. Larger diameter doesn’t always mean better sound, it can sound like a rumbling coffee can on the outside and a drone machine when lugging the engine on little to no boost.

 

2.5” exhaust wouldn’t be ideal then huh? Really close to getting a Borla but don’t want to limit the turbos later on.

 

I wouldn’t buy anything until you have a turbo in hand. It may be even cheaper to go to a shop and have them make a short pipe to dump over your rear axle.

 

Yep. It's more about the bends and shape than the diameter. I mean, .5in is not a lot of difference, especially on a stock setup with not a lot of boost, and removing cats and having proper bends is going to help the most.

Also, pretty much all the stock turbos used as twins on ecoboosts, and what would be used on a Tacoma are all going to have a 2.5in outlet on the exhaust housing anyway.

Like I said, it depends on your setup. What turbo? If its along the lines of a ko3 then your 2.5in exhaust isn't going to be the limiting factor. Either way, don't buy any exhaust until you can see how dual downpipes are going to tie into it.

 

For OEM applications, is the restriction on the exhaust so that when not in boost, the backpressure is as close as possible to when in boost? Makes it easier to have a consistent tune? Thinking out loud here.

 

Backpressure doesn't provide benefit. Scavenging does. Exhaust that is too large has too much volume and the gasses slow down and cool. You want that hot gas to travel quickly and create a vacuum behind the pulses drawing out exhaust from the next cylinder to promote better filling of unburnt air for the following cycle. Word of mouth has turned that into "see, it needs backpressure because obviously a smaller pipe has more backpressure". Take a 2.5 inch pipe compared to a 4" pipe crimped on the end to provide the same backpressure and the 2.5 inch will win because it flows better.

With turbos the biggest benefit is a pressure differential between the engine side and exhaust side to the turbine. This doesn't mean you want to choke down the engine side to artificially raise the differential. Instead you want the least possible restricting piping (if any) after the turbo. This provides the quickest acceleration of the turbine that equates to quicker spool/response.

 

Not really. The restriction on the exhaust is due to cats and all the emissions BS that is mandatory, and also due to fitting everything into a compact area.

 

Ah, I was getting the impression that OEM turbo setups had a little more restriction than NA

 

So many people on here keep complaining about cats. No one here is building a trophy truck out of their 3.5 Tacoma. We're asking an engine that was designed for 3.5L N/A to put out a lot of extra power. Performance cats can flow well and vehicles without them smell like ass to the people behind you and occasionally the passengers in your vehicle.

 

I'm not complaining at all, fyi. Stock turbo setups are designed to perform at optimal outputs with cats and all emissions on the car. The moment you try to go beyond stock and raise the boost is when the factory setup and cats need changed and/or removed.

I will always run cats on my road cars. And if/when I do a turbo setup on my truck I'm keeping the cats and emissions as close to stock as possible. I'm not trying to make 500hp. I only want more pep and torque.

 

What would it take to get a "Forced Induction" sub forum on tacomaworld?

 

From @soggyBottom.

Any irony there?

 

Irony? How so?

 

You mean like the Turbo B.S. thread, in the performance section?

 

Smog check stations are privately owned and they get only so many customers a day, if they get the chance to charge you 3-4 times the normal price for a smog check i doubt they would pass it up.
The chance of actually getting caught means an undercover cop is working the station just to give some unlucky guy a $150-1000 fine.

 

From my understanding according to a mix of LivePD and the Internet, a cop patrolling the street can pull you over for suspecting “illegal” modifications and can visually inspect your vehicle for any CARB stickers and such. No carb stickers usually means he can impound your vehicle if he wants to be a dick or he can let you go with a warning

 

Can't argue on him fining/impounding since its true. But you seriously have to have the loudest, most riced out car for the cop to be like, i need to see under your hood.