Where is my top end power?
#42
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Have you posted up the pics of your downpipe in this thread or only the other one? The downpipe could easily be the limiting factor,
With the wastegate fully open I can imagine the flow right behind the turbine to be pretty turbulent and crappy. Build that new 3 inch exhaust and I bet your power will show up.
With the wastegate fully open I can imagine the flow right behind the turbine to be pretty turbulent and crappy. Build that new 3 inch exhaust and I bet your power will show up.
#43
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Just a quick comment. Notice that your car is making more power sooner compared to the other car with the similar setup. Are you sure your turbos are EXACTLY the same? Same turbine housing? If you had a smaller turbine housing than the comparison car, with everything else exactly the same, this is what you would see. The smaller A/R spools a bit sooner, but the larger makes more power at the top end. For example the GT2560R can be ordered with either a .48 or a .64 A/R turbine housing from ATP.
Also +1 on where you are picking up your wastegate signal line. You should move it to post-intercooler if you have not already done so.
Also +1 on where you are picking up your wastegate signal line. You should move it to post-intercooler if you have not already done so.
#45
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I mentioned from the begining of the thread that there are some differences between these 2 cars and I shall list it out again:
- different design turbo outlet pipes (me: seems like it is more restrictive)
- different exhaust manifold (me: Flyin Miata, him: ebay tubular)
- i am running AEM water injection with starting psi at 4psi and ending at 14psi with the smallest nozzle that came with the kit
- I am running COPS but he is not
- wastegate signal is post intercooler from the intake manifold
We are both running the same turbo, both bought new from the same bendor, Nissan Silvia S15 turbo part number 14411-91F00, same exhause(-turbo outlet), same injectors, same intercooler. Both ran on the dyno on the same gear and same dyno settings.
Perhaps, the differences in bhp is because of the difference listed above?
Here's the ignition map, we are running 98 octane petrol here.
- different design turbo outlet pipes (me: seems like it is more restrictive)
- different exhaust manifold (me: Flyin Miata, him: ebay tubular)
- i am running AEM water injection with starting psi at 4psi and ending at 14psi with the smallest nozzle that came with the kit
- I am running COPS but he is not
- wastegate signal is post intercooler from the intake manifold
We are both running the same turbo, both bought new from the same bendor, Nissan Silvia S15 turbo part number 14411-91F00, same exhause(-turbo outlet), same injectors, same intercooler. Both ran on the dyno on the same gear and same dyno settings.
Perhaps, the differences in bhp is because of the difference listed above?
Here's the ignition map, we are running 98 octane petrol here.
![](https://www.miataturbo.net/attachments/engine-performance-56/25072-where-my-top-end-power-667105e3.jpg?dateline=1316504225)
#51
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I started off with a GT2560 on a stock 1999 engine. When I ditched my factory exhaust and moved up to something larger and more free-flowing, the turbo spooled much sooner and made more power everywhere, including at low RPM. The improvement was dramatic.
#55
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I run ALL OF IT.
Here ya go. OP's timing map with part of mine. Yes, my timing is pretty darn conservative up there because I only dyno tuned for 24psi. With WI though, I am running 3-5* more timing everywhere except for 4500-5500RPM.
![](https://www.miataturbo.net/attachments/engine-performance-56/25199-where-my-top-end-power-k3qub.jpg?dateline=1316550129)
#57
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That is the wrong location. Never take the wastegate signal from the intake manifold. Take it somewhere after the intercooler but before the throttle body. You will make much more heat in your inlet air taking the signal from that location. You will also keep the wastegate closed much more often which could restrict flow at higher rpms.
What diameter exhaust are you using? Are you using a cat? What muffler are you using?
What diameter exhaust are you using? Are you using a cat? What muffler are you using?
#58
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That is the wrong location. Never take the wastegate signal from the intake manifold. Take it somewhere after the intercooler but before the throttle body. You will make much more heat in your inlet air taking the signal from that location. You will also keep the wastegate closed much more often which could restrict flow at higher rpms.
What diameter exhaust are you using? Are you using a cat? What muffler are you using?
What diameter exhaust are you using? Are you using a cat? What muffler are you using?