I've done a lot of work to my TII. A lot of safety mods and what not. I was wondering if uping my boost to say 9 or 10lbs would make a big diffrence in HP. Here is a list of my mods.

Rebuilt s4 engine
S5 hotside and manifold with ported wastegate
TID w/ cone filter
Koyo rad
Full Racing beat exhaust
Upgraded oil pressure regulator
s5 pulsation dampner
blitz BOV
Removed emissions(cat,egr, acv, smog pump gone)


I guess what I'm asking is am I going to see a HUGE increase in power if I up the boost? Have I gained much HP over stock even though I haven't increased the boost?

The car runs great now and seems to have enough power but I'm wondering if I'm on the cusp of makeing a HUGE power increase. This is what I figure I would have to add.

Rtek 1.7
750 cc injectors
Boost controller
Fuel Pump

 

you'd be safe with all of the fuel mods

im thinking daily driving 10lbs on stock turbo cant be the best

but it can work

 

Right now I dont think you have increased your hp numbers but you may have decreased the turbo spool time which would still make the car faster. Although I haven't quite understood the differences between the s4 and s5 turbo's yet.

 

i made 255whp at 6psi, 285 at 9psi.. 3 psi increase made 30hp difference. this was with the same basic mods but with hybrid turbo. If i were you i would stick to stock boost though, until you upgrade your fuel setup

 

I think the difference between 5 and 10 psi is like night and day even on the stock turbo. It is very noticeable especially if you have an electronic boost controller so you can try the different boost levels a couple seconds apart! I would highly recommend the Rtek 1.7 and a pair of 720's, I ran this set up at 12+ psi for years with great results. You really can't beat the bang for the buck.

 

Good info guys. I'm running a very similar setup with a Rtek 2.1, 255lph pump, (4) 720cc's and BNR Stg 1 Hybrid w/ 30mm WG. Only running the stock 5psi now and looking to go to 10psi with a Profec B Spec 2 in the next couple of weeks. I believe my limiting factor is the TMIC at this point.

The fella I bought my turbo from had literally the same setup and was getting 295hp at 10-11psi....

 

The basic rule is 1psi of boost is equal to 15 Hp @ crank, or until something within the system becomes less efficent with more pressure..but 1 psi = 15 hp is normal..

 

OK, I was going to post this yesterday but wasnt totally sure of its accuracy so I kept tit o myself. AS far as ive seen and been told 1 psi of boost usually yields approx 10rwhp on the fc.

 

i generally run about 9lbs on the stock turbo thanks to having a great flowing exhaust. when my waste gate line was broken, i was seeing almost 14lbs. huge difference there. Plus it was a lot more lean...

 

Horsepower is directly proportional to air input, and air density is directly proportional to pressure. Atmospheric pressure is 14.7psi. So by going from 5psi on the gauge to 9psi on the gauge, your absolute pressure climbs from 19.7psi to 23.7psi. That's a 20% increase in power. But if you don't get rid of the extra heat (with a big enough intercooler), the compression increases the absolute temperature of the air by about 5%. Density is inversely proportional to absolute temperature. Overall you get a 14% boost in horsepower.

See http://en.wikipedia.org/wiki/Adiabatic_compression for finding the temperature increase in a gas during adiabatic compression ("adiabatic" = no heat removed nor added).

This assumes you don't richen the air-fuel mixture, which you need to prevent detonation (please, please tune rich and don't blow your motor later). The richer air-fuel mixture will decrease the engine efficiency which will make you lose a little of that power. Plus the turbo might generate heat from friction to increase the temperature even more. The numbers above assume a 100% efficient frictionless turbo.

So I'd say a 14-20% increase in horsepower tops, probably a little less. Assuming stock intercooler, I'm gonna guestimate 205wHP @ 5psi and 240wHP @ 9psi, for a net increase of 35wHP. That's pretty close to BklynRX7's estimate, so hopefully I did my math right. I'll bet that's half a second to a second on the 0-60. The stock FC NA is a second slower than the stock turbo, a "fast" modern sports car is a second faster than an "ok" sports car, etc. So ya, it's a major upgrade. But please tune properly, manage fuel properly, and control boost properly to avoid (possibly) instantly blowing your motor at some future point in time, often without warning. Engine rebuilds are $2,000-$3,000 or more.

 

well put eric =]

 

Hey guys,

After I hook up the turbo and the external wastegate to the manifold, how do I know that my boost level will be at the low or high by using a manual boost controller? Will there be any required adjusting on the bolts of the external wastegate, the ones that connect to the manifold? Or do I just control the boost with just the **** on the boost controller?

Thanks,

 

murgocurgo87, Your post seems off topic. You should use the search option, it works great. To answer your question though, external wastegates are set for different boost levels by changing an internal spring, not a boost controller.

 

I'm surprised you haven't don this yet if you're taking the "safe" road.
The stock fuel pump is being close to maxed out, and I bet it's not getting full voltage.

Don't be trying to make more power until that fuel pump upgrade is installed!


-Ted

 

So my next upgrade will be a walbrofuel pump! Thanks for letting me know Ted

 

I'd say $100 and 20 min to install is worth it. Plus another hour or two to rewire, and you are good to go.

 

The fuel pump rewire is needed in these cars.

 

also, an alternate route - drop an FD pump in.

 

^ thats what I did and I got great results for cheaper than a walbro pump. I believe my FD had 800cc primaries and 800cc secondaries stock. So lets say you're good all the way to 720 primaries and 720 secondaries on a FC with no problem on a FD fuel pump. I personally recommend a FD pump, Rtek 2.1, and a 720 primary and 720 secondary fuel setup. I have a EBC and can definately tell the difference between 5 and 10 psi when I change the boost. My FC with the FD pump in it Was a NA so I didn't have to rewire the pump but you may have to on a TII to get all it's potential...

 

The stock FD fuel pump doesn't flow that much more than a stock FC turbo fuel pump.
Hard numbers are here:
http://fc3spro.com/TECH/MODS/FUEL/fpump.htm

The "255lph" Walbro blows away the stock FD fuel pump, hands down.
Really, for $100, the Walbro significantly increases the fuel capacity, unlike the stock FD unit.


There is no reason to upgrade the fuel pump on a non-turbo FC unless you're running a really radical set-up.
A rewire is really all that is needed to ensure proper flow, as the stock FC non-turbo fuel pump can support 200hp at the wheels easily.


-Ted

 

Thats total BS. No stock turbo makes that much.

I ran that kind of setup, made 289rwhp

 

In his post he specifically said he has a hybrid turbo, check out the BNR hybrids, they are very capable of the power claim he made.

http://www.bnrturbos.com/2ndGen.htm

 

remember folks, CFM makes power, think of boost like the percentage of CFM that the turbo can put out. Just another reason why not all turbos are created equal, which would be the case if psi was psi regardless of turbo.

10 rwhp per 1 psi sounds about right.

 

All I'm saying is if a FD pump can reliably run 4 800cc injectors at 14 psi (like my FD) then a FD is just fine for 720's at 5-10 psi. I can pick a FD pump up for 30$ and a walbro for 90 so in the end I think the FD will work just fine and be cheaper if someone cares about price. But don't get me wrong, I have a walbro pump in one of my TII's.


I said WAS a NA. As in it came from factory with an NA engine. Since then it has been swaped to an incredible S5 13BT setup. the only thing NA about it now is most of the body but not the drivetrain.

 

whats stock psi for a T2?