So I dyno'd my GT4082 setup. I made 427rwhp at about 17 psi. the boost in this graph is innacurate and off by like 3-4 psi. It went up to 21 and trailed off down to like 16 up top... the turbo cannot flow this much air.. oh yeah, stock motor. s5 block

anyway heres the graph red is boost blue is horsepower

 

Not bad, nice dyno

 

Wonder if the motor is the flow issue as opposed to the turbo? assuming stock ports.

 

BTW, what dyno is that that, that will scale boost, and HP?

 

it was a clayton. there was an external map sensor hooked up to an auxillary input just so they'd believe my boost was actually dropping off =]

I'll be dynoing with a PT61 I am getting this week. expect numbers soon

 

and as for the flow problem, steve kan had the same problem with this turbo on a street ported motor

 

With all do respect, and he deserves plenty, Steve seems to have "boost stability problems" alot. For starters, he likes to read boost/control boost based on the psi at the compressor, not the motor. To me this does not make sense, you are not accounting for losses in the system, and really do not know what is going on. I could see using a second boost gauge to measure boost at the compressor as a reference, but I do not agree with plumbing the boost controller from the compressor. Did he have you change your hoses as I describe by any chance? Carl

 

I read boost from my intake manifold. the wastegate stays shut, no leaks... turbo is just out of breath.. if you look at the compressor map you see it runs out real fast....



.. so im upgrading to

 

Please... do your next dyno on a Dynojet if you can. I've never heard of a Clayton!




Brian

 

So you used a .58 hot side??? Pardon my ignorance, for the amount of time I spend on the forum, you would think I could read a simple compressor map. If you did not use a .58 that graph would not be accurate, yes?

 

Its 4am, so my brain could be fried, but I'm pretty sure NYT tunes his own car. I think his Steve Kan comments are referring to this thread https://www.rx7club.com/showthread.p...4&page=1&pp=15

 

this much horsepower on a stock s5 block? wow.

 

the .58 is the ar on the compressor housing, not the turbine.. turbine is a .96GTQ.

 

well said =]

 

Carl,
for an electonic boost control, the boost reading is always read from the intake manifold (the least harmonic point). However, the solenoid lines are tied as close to the turbo as possible to prevent any boost fluctuation. If the boost line and the boost reference line are at the intake manifold (where most people tied to the same reference point as the boost guage), you'll see a noticable boost fluctuation as the port opens and closes. This is the same concept why we have fuel pulsation damper to prevent fuel pressure stability. Generally, Boost reading should be tied as close to the stock map sensor pickup (by the throttle body) and the solenoids pickup point as close to the turbo as possible. If you're running a manual boost control, the pickup line is generally as close to the turbo as possible since it creates the least amount of harmonics in the system.

You have to remember that both the manual boost control and electronic boost control operates differently. Manual controller is a passive device/system where as the electronic boost controller is an active device/system.

manual boost control restricts the air flow (pressure) to the wastegate to allow the boost to come up based on the restriction.

Electronic boost controller reads the boost level at the manifold and then sends the correct duty cycle to the solenoid to restrict the wastegate flow accordingly.

Hope that makes sense?

 

Steve, that makes sense, but you had me move my boost control reference(avcr solenoid) to the compressor when you tuned my car, thus my question. I did move it back to the manifold since. I cannot believe a GT40 .96 GTQ is running out of breath so soon , I guess I really need to spend some time with compressor maps. Carl

 

Steve, I want to say, I understand that you are an accomplished tuner, just trying to learn the tricks of the trade. Regards, Carl

 

what do you have for an exhaust?
Did you try running it open?

 

Carl,
It's been awhile since I touched your car so I may have forgotten some details. If I remembered correctly, I think that we were experiencing boost oscillation with your car and couldn't find a good pick up point in your manifold after several try. So instead of wasting time on the dyno debugging, I think we went ahead and tied the boost controller to a less oscillated area so that we could actually get some tuning done and deal with the oscillation later. I think I remembered asking you to put a damper/filter in line with the boost controller to reduce the osciallation once the car is tuned? It's a little blury for me to remember what was actually happening in your case.

 

racing beat. i've run it open with same dropoff.

why doesnt anyone look at the compressor map? I posted it. look how fast it comes up on compressor choke.

 

This is the smallest GT-40 (compressor wise). The wheel is smaller than a GT35R wheel (which is in the PT61 that will arrive very shortly to me =])

 

Actually that was Dave's car, we switched mine before even trying to dyno do to the problem ewith dave's car...

 

That was my car.
I fixed my boost stability problem the next day as there was only so much we could do at the dyno with the time constraints.
Before the fix, my boost would fluctuate by almost 3 psi.

Before the fix, I was taking both my boost reading for the Profec B and the solenoid at the upper manifold right behind the tb.
Now I only have the the Profec source at the manifold and tapped a fitting into the comp housing to take a reading for the boost control solenoid. I also moved my solenoid closer to the turbo, therefore shortening the lines which may have helped additionally.
That is what Steve recommended.
Boost stability problem solved.

 

make sure your not pissing boost out the BOV.

 

My bad. I guess my memory gets worst with my old age. LOL