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Discussion Starter #1
Quick question for you guys/gals:

What would the approx rwhp level be with only a dp, bcc, and exhaust. Stock air intake, no boost controller, and with boost levels around 16psi.

Thanks!!!
 

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My car...

Intake (K&N on the end of the pipe picking up hot air), DP, exhaust, pulled about 327RWHP right off the street. Resetting the ECU yielded 338RWHP. Pulling the wastegate hose ended up at 389RWHP and 427ftlbs. The first two pulls were probably right around 14PSI or so. No boost controller on it but the clear exhaust appeared to let boost climb jut a little bit. Since the FFCD mod was done I could go over 14PSI but I believe it effected the 2nd turbo's spoolup - a dip in my curve would seem to indicate that as well. Come 4K though it pulled like a freight train :) I'll be removing the FFCD mod ASAP and awaiting an AEM ECU to go further...

Does that help at all? Your mods sound close to mine...
 
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Discussion Starter #4
376 @ 16-17PSI with check engine light and MAD humidity with junk clutch.
 

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SpooooL
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I searched around and I need some info. What exactly does the wastegate do? I have a pretty good Idea what it does but I dont like settling for knowing just a little. If you know where an article describing it is, please let me know.And what happends when the hose is pulled? I dont remember seeing that on MKIV.com.
Thanx
 

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Wastegate...

Wastegates act like the floodgates at Hoover dam. When the floodgates on the dam are closed the water is forced to go through turbines to produce electricity - like your turbos producing boost. However if the turbines begin to spin too quickly or too much water backs up behind the damn the floodgates must be opened to relieve some of the pressure - same thing with your turbos.

As your turbos approach the wastegate setting, 11PSI stock, a flap begins to open allowing exhaust gas to bypass the turbos. As you reach the preset boost limit the flap opens wider to hold the boost at the preset level. Sometimes the wastegate simply cannot flow enough exhaust around the turbo and boost will still rise - that's boost creep. T-bleeders like what you've got installed will weaken the pressure signal to the wastegate allowing boost to rise higher than the preset wastegate setting.

Pulling the wastegate hose will prevent the wastegate from seeing ANY signal and boost will climb a great deal. The turbos on the Supra are apparently small enough that the turbos simply don't produce enough boost to blow the motor, at least not real quickly. The downside is that when you do this the turbos spin VERY fast - out of their design range in fact. This is "bad" for them and can lead to an early failure (ahem). Long periods of high boost like this, say on the highway, would really stress them.

Also, when the turbos spin that fast they heat the air more than they would when operating within design spec - at some point you get diminishing power returns. This is also why single turbos at the same boost level will often make more power than the twins - the air temp is cooler because th ebigger turbo is more efficient.

Oh, electronic boost controllers are better because they will prevent the wastegate form seeing ANY pressure or opening at all until the desired boost is reached, they will then cycle a solenoid very quickly or open a valve to maintain the boost level you've selected. Some manual boost controllers can also do something like this using a check valve but I've yet to try one (built one, not had time). Fuzzy logic controllers work by learning just how close to the set limit they can get (without overshooting) before opening at all. This makes them "better" so far as response goes bu tthey don't always work well in all applications. Sometimes the solenoid in an electronic controller isn't strong enough to withstand the amoount of boost you run with out leaking air past - at this point you can no longer raise the boost further, something to keep in mind in high boost apps like some Supras.

Hope that helps! :D
 

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I have a BCC, RMM DP, HKS Super Dragger, and TurboXS boost controller. The first run right off the bat I pulled around 325hp and around 380lbs at 1.26 bar (I don't remember that well since I didn't print it out). Pissed off, I reset the ECU and removed the air filter. This time, I pulled around 340hp with around the same torque. Also, this time the technician there told me that I was detonating. After several more runs, with each time turning down the boost and reseting the ECU, I came to the final numbers: 350.5 hp and 329.1lbs at 1.16 bar. This is obviously disappointing to me. I was running on 91 octane so that could be the problem, but this is still pretty bad for a BPU car in my opinion. Can anyone offer me any advice on how to prevent the detonation? My car is a 93.5 w/ 38k miles. Any other feedback would be appreciated. Thanks
 

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SpooooL
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What kind of spark plugs are you using? Also, your probably running rich like I am. Try 93 octane and maybe some octane booster. A fuel controller on your next visit will help. Also, get your A/F ratio checked.
 

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BoostAddict said:
I have a BCC, RMM DP, HKS Super Dragger, and TurboXS boost controller. The first run right off the bat I pulled around 325hp and around 380lbs at 1.26 bar (I don't remember that well since I didn't print it out). Pissed off, I reset the ECU and removed the air filter. This time, I pulled around 340hp with around the same torque. Also, this time the technician there told me that I was detonating. After several more runs, with each time turning down the boost and reseting the ECU, I came to the final numbers: 350.5 hp and 329.1lbs at 1.16 bar. This is obviously disappointing to me. I was running on 91 octane so that could be the problem, but this is still pretty bad for a BPU car in my opinion. Can anyone offer me any advice on how to prevent the detonation? My car is a 93.5 w/ 38k miles. Any other feedback would be appreciated. Thanks
Run at least 93 octane and change your plugs. I never had a problem detonating with stock plugs, but change to some NGK 3330's. They are a heat range colder and a closer gap. Some people run a different NGK. I can't remember the # right off hand, but it's the same gap and heat range.
 

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I would use 93 octane if there were any available around here. Does anyone know where they sell higher than 91 octane around San Francisco? I am also using stock plugs, but I just bought some NGK 6097's to see if that'll help.
 
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