Boostage

Is the GSR's intake system with the Butterflies, better for low and mid range than the b16/ITR/skunk2/aebs/etc etc style intake?

Motor will be a b16 with a gt28r with OEM b16 cams, not trying to make any power past stock redline, however looking to have the longest, flattest TQ curve with this motor.

TheShodan

iTrader: (14)

Somewhat. either of those will do fine.

90ED6LSV

i'd remove the butterflies if you stick with the stock manifold.

typically, the larger intake manifolds will loose a little torque, but with boost, it's mainly the turbo spool-up response that will make the biggest difference... a gt28 should spool pretty fast so you're powerband should have decent torque numbers.

I've heard that the longer runners increase mid-range, and short runners with a larger plenum increase high-rpm power.

Spawne32

iTrader: (3)

edelbrock performer x

0VRoomdeal

Well if you going to go under under 15psi of boost I would just run a ITR Manifold but if you going to go over that go with the Victor X

TheShodan

iTrader: (14)

Even with higher boost levels, a victor X wouldn't be ideal as the GT28R is only rated at about 35lbs/min. Even the stock intake has the capability of keeping a good lower to midrange torqueband regardless of boost pressure level.

Tony the Tiger

There are upgrades that improve VE and make more power @ same PSI of boost with a given turbo, but sometimes these upgrades end up focusing the power at a certain RPM band.

For example, a larger intake plenum with relatively the same runner lengths as a stock'ish IM will generally achieve better power per PSI of boost, but focuses that power gain at a certain RPM range. e.g. The engine makes more power from 4000-7000RPM, but 7000-8500 it doesn't gain anything. This nets you a falling torque curve at the same PSI of boost. The more you increase boost, the more exaggerated this torque falls off. Next example, by getting a bigger intake manifold like an ITR IM or a Skunk2 IM, will now yield better power from 6000-8000RPM, but take a loss from 2000-4000RPM. Generally, you want to make the power as early as possible, so a bigger IM is not a good choice.

You want to choose parts that will offer a broad power increase and with the widest useable range. You have to mix and match some parts that may "seem" to be a bad idea when combined, but the goal is to flatten out the curve. You may need to run more boost to achieve the same power though due to some parts working against each other by theory, but it can result in a nice flat torque curve and earliest possible spool, and maintains this flatter curve as you increase boost.

If you chose a smaller GT28R turbo and a smaller A/R housing, you would want to use a ramhorn or a nice long-runner exhaust manifold with a decently sized wastegate. The smaller turbo will spool up quick, but will naturally choke at higher RPM's. The long exhaust manifold will help relieve that exhaust pressure, and the larger wastegate will reduce exhaust turbulence once it opens. Bigger gate and small turbine housing will eliminate any spiking, or sudden variations of engine VE during spool up and such, so the turbo will also respond and recover faster between shifts.

With a smaller GT28R + long runner exhaust manifold, will allow a larger window for tuning and extracting power. You can bump up the compression ratio (11.5+:1) if you have the choice to do so. Bumping up the compression lowers BSFC, which also makes more power with lesser airflow from the turbo.. i.e. The same 30 lbs/min of airflow can make more HP with higher compression, therefore, it also puts out less exhaust gases for the same given power. This in turn, helps keep torque flat at higher RPM's with a small turbo because it reduces the liklihood of it choking.

For intake manifold, it is a critical part in determining HP/TQ before the turbo spools. To get a turbo spooling faster, the goal is to cram the engine with the most air and fuel into the cylinders before the turbo gets moving. So you are kind of improving the VE of the motor while it is still in 0-vac. So I would stick with an AEBS, or a stock B16A intake manifold and throttlebody. The sooner your engine can deliver torque, it also means more exhaust gases and energy gets sent to the turbo, thus, spool up sooner.

For the intercooler, the worse enemy for a small turbo is heat... You would want a tube/fin intercooler, or a Precision w/ Garrett core that boasts excellent core efficiency. You can take a bit of a hit on pressure drop... For a small turbo, you'd want to make sure the air is cool. It's no coicidence that Japanese tuners, like HKS, Greddy, Blitz, etc.. are all tube and fin cores, yet all the drag racers here in North America or in Australia are all about bar/plate. Drag racers means big turbo. JDM tuners are always about spool and recovery on rather smaller turbos.

For cams, the B16A cams will be the best choice... You don't want anything bigger with a GT28R turbo because overlap will become an issue. Rather install a set of adjustable cam gears, and phase them in a fashion which you can manipulate the torque curve. You can retard the exhaust cam only (but leave intake at 0), and if the combination of parts is good, it will not affect spool time but allow a higher powerband. At one point, I had my cam gears at IN 0, EX -7 on my Integra w/ ITR cams and it allowed my torque to keep flat for another 500RPM.

For the exhaust system, you should use a 2.5" downpipe, and then flare it up to a 3.0" further downstream of the exhaust. The smaller downpipe will allow quicker exhaust velocity at lower RPM's so the car will make torque sooner, but flaring it out to 3" further down makes sure it doesn't choke as you get into higher RPM's.

It's funny how when we begin to shape the torque curve of a turbo setup, it all brings back to the whole N/A all motor approach and making parts work together as a combination

Boostage

Tony thanks, You know I was going to PM you this on Supraforums, but some how figured you got out of Hondas. thanks for all the info sir.

TheShodan

iTrader: (14)

Nah, Tony just gets involved with as many platforms as possible. People like him don't "get out" of any platform. It's kinda like an urban gang. Once you're in, you stay in

Bseriescivic5

Very informative post tony, Thanks for chiming in.... Its really nice to read into the theory a bit more, and understand exactly whats going on

civic_si81

Tony:

Good write up learned a couple of new things I didn't know.