Discussion in 'Forced Induction' started by Ractive78, Mar 15, 2003.
HOw much psi do you think a stock gsr motor could take safely, and still be a daily driver?
-12 to 23213123123 psi
it all depends on the turbo size, the tune, who tuned it, and so on and so forth.....
my typical example.
10 psi on a 14g = 100 whp gain
10 psi on a t88 = 500 whp gain
BUT IN ONLY RUNNING 10 PSI, why did i blow up? cuz your turbo pushes more air than a jet engine's exhaust!!!!
I didnt know you could run ngative boost. Does running negative boost take away power?
negative boost is also known as vacuum, or whatever everyone else calls it- lag
5 or 6 psi would be alright without any serious tuning. Just make sure you retard your timing a little, and get a good fuel management system.
The most ANY size of turbo will increase the horsepower of an engine at 10 psi is about 70 percent, and for a GSR thats about a 120 hp gain
we'll see about that.
i'm looking for about a 200-220% gain at 10psi.
dyno coming soon
ask calesta to explain the math if you dont believe me.
10psi is where your BOV goes off keeping anymore air from going into the engine. 10 psi is about 70 percent more pressure than the ambient air pressure of 14.7 psi at sea level. It is the difference in air pressure that forces more air into the engine which creates more torque.
If you have 70 percent more going into the engine, you will make approximately 70 percent more torque. If you have a 14g and a t88 on a gsr running 3 psi you will be making the exact same horsepower (as long as the 14g is able to push the full 3 psi at the gsr's redline). Infact the GSR with the 14g would actually be faster because it causes less drag on the exhaust system, and is in boost for a larger portion of the rev range.
But if you were to put both of those turbos at 21 psi, the 14g would not have a chance in hell of pushing that, and the t88 would still be blowing air out of the BOV. So in that case the GSR with the t88 would be pushing 250 percent more torque, and the 14g be screwed.
hahahahaha, that's the most retarded thing i've ever herd. i'm sure you misinterpeted that from calesta, cuz i'm pretty sure he wouldn't say something that dumb. and the wastegate is what opens up at a set psi, not the bov. the bov is what opens the the throttle body closes to release the pressure in the charge pipes.
alrighty ignore that link to calesta. I still want to see that dyno at 10 psi , and the dyno of it running without the turbo. If it is a 200 percent increase I'll apologize.
Here are dynos from 2 different 10 psi gsr's
I DOUBT Calesta told you that, if he did,
here's the deal.
a BOV only opens when you set it to open. on top of that, it doesn't operate off the wastegate or the vacuum system's boost/vacuum lines. it detects pressure in the charge pipe. IE, when your throttle body closes, there is immediately tons of air/pressure waiting to go in, since it has no where to go, it back logs to the turbo. doing that causes damage to the turbo, as it tries to spin in backwards. The bov is designed to release this extra pressure- which is MUCH MUCH MUCH higher than your actual boost setting.
10-11 psi is all you can run on your stock map sensor. That's only because its a 2 bar sensor. ambient air pressure is about 1 bar. so, come 10-11 psi, you are reaching the limits of the stock map sensor. the map sends a voltage to the ecu based on this pressure.
not true. psi means jack and shit. and Jack left town. its all about CFM's.
10 psi on a 14g flows, say, 200 cfm's.
10psi on a t88 flows, say 500 cfm's.
its more than twice the air flow. air + combustion = power.
at 21 psi, the 14g would only be pushing in heat. correct. its simply out of its range. however, the air blowing out of the BOV is, again, bullshit.
I was under the impression that both the BOV and the waste gate opened at a given psi
Im not ripping on anyone, or even claiming to know everything. I am just saying that if the MAP sensor is reading 10 psi at full throttle from a 14g the horsepower gain will be exactly the same as if the MAP sensor is reading 10 psi from a t88
while THAT particular setup may only be a 70% gain, those numbers are VERY VERY weak. thats a typical drag turbo setup. AKA lame dick. t3/t4 on a pretty much unbuilt motor (at least it doesn't say) with low compression. compression has a LOT to do with power, esp. torque.
I will be running a t3/t61 on my 2L gsr/b16 head motor.
goal: 400 whp at 10 psi
once its in and tuned, i will post the dynos
It appears I had a misunderstanding of the bov/waste gate. However, like I said, an engine with a t88 reading 10 psi at the MAP sensor full throttle at a given rpm will make the exact same HP as the same engine running a 14g at full throttle reading 10 psi at the MAP sensor.
psi does NOT equal air flow
Okay I read it. Thats one more variable I've got to consider. However 10psi of air at a given temperature at the map sensor on a given engine at given RPM at full throttle from a 14g and a t88 will make the same amount of horsepower.
Just a note though, mecury is not the heaviest element. Uranium 235 is almost twice as dense as mercury. The engine may be partially heated by compression(but its also cooled almost as much when the air is released), but its mostly heated by the fact that its burning gasoline
this is the last time im going to say this.
who ever told you that, or hwo ever you are derriving it is just utterly wrong.
PSI has ZERO relation to the amount of air going into a motor. that is cfm's. cubic feet per min of air.
at 10 psi, a 14g flows 200 cfms
at 10 psi a t88 flows 500 cfms
500 cfms, mated with proper fuel STILL at 10psi will make MUCH more power.
there is no arguing it dude.
yeah you are right, there is no point in arguing about this. however, full throttle and 10 psi means that the engine cannot take in anymore cf/m
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