What is the stock boost at on a turbo II motor? and how high can you push it up to safely? with everthing stock. thanks for the help.

 

i have been told 9 is stock, i have a manual boost controller and set at 12 when i feel like having fun, but my motor needs a rebuild anyways...

 

S4 (6.56psi boost)

S5 (8.25psi boost)

 

Well, racing beat claims 59hp w/ their rev TII exhaust w/ no other mods than an FCD (fuel cut defender). I'd have a hard time believing you could pick up that much power @ anything less than 10psi. Then again I'm sure they tested a car with injectors that were known to be flowing properly.

For that reason, and because I've seen a few people do it, I'd say 10psi is the upper limit of what you can run on a PROPERLY FUNCTIONING stock fuel system.

Its 20+ years old, I'd check all the lines, and replace various components just for peace of mind regardless.

 

So this is what the stock wastegate opens at when you connect it straight to the turbo?

 

with boost spikes up to 10+ with the open exhaust I wouldnt be surprised if it makes more then 59hp

 

^^ ditto.

 

An open up exhaust and or intake with stock boost levels results in MORE power. i run 6 psi all day long... and its way faster then stock.

 

http://fc3spro.com/TECH/FM2W/power.htm

The wastegate begins to open before that. Mechanical wastegates usually open gradually as the boost increases rather than suddenly popping open at a set boost level. Highly-modified cars often have an electronic actuator which can pop the wastegate open very quickly if desired.

The stock wastegate is an integral part of the turbocharger unit, so it is always connected straight to the turbo. This is called an "internal wastegate".
http://en.wikipedia.org/wiki/Wastegate

 

I don't doubt that you're faster because you're getting to 6 psi quicker, but you are not making more (peak) power. Especially when you consider the trade off between the increased air flow and increased air temperature that come w/ placing a free flowing filter in a hot engine bay.

Staying at 6 psi is pretty impressive, how do you combat boost creep? stock air box? external wg?

 

There you go making noobish assumptions about my setup. it's a 34mm ported internal wastegate, and boost creep solution i tried to explain in another post but no one paid attention. without this secondary mod my 34mm wastegate still hit fuel cut at 5000RPM IN 2ND GEAR.
and it's a fender intake if you must know.
i guess it's my noob asses fault for not going and getting it dyno'd.

 

I'm sorry, didn't happen to see that thread. Got a link? or perhaps you could post your solution here because a lot of people seem to have that problem.

 

I read in another post you feather the throttle to keep the boost down, lol.. i remember doin that... a few years back, what a pita!
just get some carb springs from autozone and hook them from the wastegate arm to were the firewall meets the frame, there's a little hole there you can use... i am using 3 of them, they are throttle return springs and come in a pack of like 6 of diffrent sizes.

basicly you take about 4 pounds of load off the 5 pound spring and the waste gate cracks at about 3 psi, and is fully open by 6-7, and you get a rock solid boost pressure. i have pics but there on the work pc i'll upload them tuesday if you havent figured it out.

if i take the springs off and add a FCD i get a rock solid 11 psi, so 11 minus 4=7? seems simple enough right?

even after the springs i have hit fuel cut in 5th before, but only once and it was about 20 degrees outside.

 

I used to run 14lbs for two years before the ol girl gave in.

 

Awesome! That makes perfect sense, pics are always helpful though.

Which sizes are you using?

I'm currently running open 3" downpipe (waiting for my borla xr-1 to arrive) which means I hit fuel cut backing out of my driveway funny because I didn't hit fuel cut running open stock downpipe, guess that cat is REALLY restrictive.

Once I get my mid pipe made and bolt up the rest of my exhaust I'll have to try this out. I need to find someone selling an Rtek....

 

my car stays a solid 7.5-8psi. full 80mm exhaust, s5 turbo, profec b?, haltech. its much quicker than my buddies car at 10psi with basically the same setup so im happy. ive also gone through my fuel system, and upgraded to a 255walbro.

 

Here you go, the springs are maybe 3-4 inches long, you have to stretch them on and they'll b in the 6-8 inch range.

 

^^ what other mods are you running? seems like it would be running super lean before you reach full boost? your set up is intriguing though. i (accidentally) ran straight pipe and it would be full boost at like 3k rpm but was prob spiking out to like 15? but it was dam crazy

 

460cc primary( shhh! ) 750cc on the 2's.
34mm ported waste gate, back plate ground down.
3in tid, fender intake, 3inch back exhaust. 9.4 s4 N/a rotors. you know all those dangers things they say not to do. oh yeah and a wide band and a keen eye.
i get 23 mpg avrg, and well my power is unknown.. maybe 240 on 6-7 psi?
i'm sure i left out something.. i have about $280 in this motor..
steady 7 psi on 460cc doesn't lean out but it's in the 13's when it's cold..
i too am waiting on an 7 rtek so my 750 injectors aren't even plugged in. well one isn't. i dont rev over 3800. kinda want the afm delete.

i also only run 87 oct, lmfao.

 

how do you do an afm delete? and why? i was under impression stock s5 injectors were 550cc already. you're not running any engine management now?

 

rtek doesnt support the AFm delete but they're working on it. no i am on the stock ecu and i am running the 460cc N/a injectors... too lean them out during idle and cruise and well anything under 3800. i get no problems under 3800 with 87 octance and N/a ROTORs.

However, if i chose to redline the engine would surely blow.. i have to put 93 octane to redline, that's why i need to get an rtek and take the advanced timing back a few points and then i could continue to run 87 octance as i wish. that's why my secondary injectors are unplugged, so i dont rev to the DANGAh ZONE.

 

hmm now i get it. sounds sketchy as is, but will be sweet after you get an rtek. thats the route i would like to go but don't know enough and i don't live near a tuner. i may just get a wide band, 720 secondaries and a vafc to see how far i could get on my own. i'm running an se pump. know of a brand that makes 720 cc that will use stock wiring plugs?

 

http://www.rceng.com/

 

WOW!

That, my friend, is one scary setup. I'll let the next Rtek go to you lol

Interesting that you mention running 87 octane, I always wondered why everyone feels it necessary to run 93 as soon as they do even the most basic mods.

Now that "23mpg" you mentioned is that highway or city? The former I would understand, (I get 25) but if thats city, thats gotta be a record. But w/ now secondaries and 460's....

oh, and I hate to be a bubble burster, but theres no way a stock turbo (assumption) is putting down 240 @ 7 psi. I'm sure you'll get there quick once you have some fuel control though

 

it was 15.1 gallons for 334 miles. tank average.

i think that if i redline 4th gear on a dyno, it would creep to fuel cut, or maybe hit 10 psi if the FCD was installed.

we'll see i'm going to try to get it dyno'd in the next week. some 93 octane hopefully will save the motor and not blow it before deals gap... but we'll see.