you mean like this:

http://www.boostedmiata.com/dynos/in...are_boost1.jpg

I question the idea that the TB is too small for a turbo app (unlike in a s/c app), given that the volume flow rate remains the same under boost (air passing through is compressed).
However IF the motor's VE is increased at the topend (such as with a mani or cams), then it IS possible the TB is too small.

then why is the torque dropping like a rock?

It's not that torque drops, it's that horsepower is constant. :-) A clear sign of flow restriction.

Well, there's an idea. Just put a small restrictor on the Mazda one. If you've got headroom, it won't make a difference. :-)


Several OEM's have done this. Technically it wasn't to get more top end, it was actually a boost hole at the torque peak to help the motor/tranny survive.

Of course, what you're really talking about doing is adding another axis to your dyno tune. You can sometimes get more power on 12 psi than 14, if you're heating the air less, can run more timing, etc. You would need to find that peak of boost, fuel, and timing for every RPM, and it would take a while. Because the question comes to mind, if you're going to add two psi up top, why not add it in the middle, too?


It depends where the restriction is. You could make the same argument about the valves, that it doesn't matter. It could easily be in the intercooler track as well. You really need to look at pressure all along the path. Certainly at turbo outlet, and at TB inlet (in charge piping) and in manifold. Without those three numbers you're building hardware based on a guess. And it's EASY to do. Turn off barometeric correction, run a line somewhere, and log it. :-)

If the TB was too small, you would have 15 PSI outside of it, 12 psi in the manifold. Or, think about it like this - the volume flow must be higher: the cylender has the same pressure, and the turbo outlet sees higher pressure. Flow is monotonically increasing function of pressure differential....

I can see the argument but I'm not convinced it holds. We could argue all week, but two boost gauges would tell us really quick.

Seems simple to test. I do know I have to add a lot of wastegate duty cycle to maintain boost (14psi) on the dyno. I never know what the MAP value is before the TB...hmmm.

I hate having 2.5 intercooler plumbing, and what, a 55mm (2.125") throttle body?

I think I'm going to put a pressure gauge T'd into my WG supply line (at the turbo compressors). I should have a boost gauge lying around. EDIT: Actually I could use my standard gauge for pre TB and the ECU's map sensor for Post TB...duh.

Awesomely flat torque curve :bigtu: Yeah, like that, except maybe without the midrange power loss. Even though they are making the same peak power, I prefer the 'blue' line of course.

I was thinking the same thing more or less. Keep the torque at a 'reasonable' amount, then make more power by keeping the torque flatter into the upper RPM ranges via ramping up the boost. You are right though, it adds yet another axis to the tune. I'll have to see if the tuner is up for that, or more importantly, my wallet.

Hell, I had ALL of this stuff figured out :jerkit: and was getting bored, so I was looking for a new challenge anyway :facepalm:

Yeah, shouldn't be too bad. And anything which will log a voltage will work. Also, a differential pressure gauge would work, I assume... Here was a simple thing I did before - moved my MBC wastegte signal. On the turbo outlet, I got 12 psi, dropping to 9 by redline. At the throttle body I held 12 the whole way. Conclusion: There was 3 psi of drop (increasing as a function of flow) across the IC and it's piping.

Nu-uh. The red one would be more fun to drive. :-) That feeling of the gift that keeps on giving. It wouldn't be as fast, but it would be more fun. Plus, pretty clearly, one of them has nothing but win if you remove the revlimiter.

It certainly adds another axis, and of course, they aren't independent. It means a lot of tuning. But, much like the blue-line car is faster even if less fun, there's no "reasonable" torque. You want to figure out where you get the most power at the onset of knock and back off 1*, 0.1 AFR, and 1 psi.... And be there everywhere. If that means the car has more midrange than top end, or visa versa, so be it. It'll be the fastest on the drag strip that way.

If you want to use it for more detailed work there may be tradeoffs. Even so, start with that "best" situation, then remove power where you want less.


oh yeah. me too. I'd love to be NA so I could just go "yeah, it's a fun car" and stop wondering how to squeeze 3 more hp or 5 fewer degrees intake temp out of it.

I'm extremely jealous, congrats on getting this setup going. Can't wait to see some track videos of it :)

ACS Roval video. 146mph on the banking.

That looks like a stoopid amount of fun!

Get some fucking gloves, man.

Now you know why I was so giddy when I finally got mine on the track...with another 200lb considering that I'm huge and shredded. Its like murder out there with this kind of power.

btw, I was just watching top gear and the Ascari went 0-100 in 8 seconds with a power launch. Apparently you and I are in Ascari territory...if we stuff enough rubber under it.

Fucking badass!!! What's it like raking in a Porsche like that and then spitting him out?
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god andrew! Buy a damn camera mount that doesn't shake like hustler's bed when you put in a quarter!

So is a 3.63 the next step after you bolt your turbo back together?

I think a good camera would be more beneficial

Win

Yeah, definitely. I never thought I'd need that much gear, but with 200whp I need about 135mph worth of gear at Calspeed. With 280, I needed 152-153mph worth (only had 146). With 350+? I hope 165 (7400 with 3.63s) will be enough.

bah!

awesome vid! i hate nascar, but i bet it was fun on the banking huh? TWS here in texas has a better infield course, but you only go out on the frt. straight on the banking. even so, i get to about 140mph with my car on low boost. my buddies evo hits 150mph. i bet you would top out here too. car sounded awesome. sounds alot like this little crx time attack car i'm working on. it's making the same horsepower as your car, but it weighs 1950lbs! i can't wait to test it out with the new suspension,aero,power (used to make 238whp) rear mounted rad.,and tires.

You hate NASCAR until you actually try driving on an oval. 145mph is nervous in my car. I doubt I could do much more than about 155. I cannot imagine doing 185-190mph around those banks.

Thank you, I hate people that think that's easy. I'm not a huge fan of Nascar but I have respect for what they do.
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