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Boost Junkie
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Discussion Starter · #1 · (Edited)
I took my car to the local dyno yesterday to get final numbers with the MAF in place before I convert it to speed density via the MAPECU. My set up is as follows:

SP67GTQ complete kit
4 in. DP/MP
BL Exhaust
Greddy 3-Row
264 intake/256 exhaust
BL Trans
PI/MW 3800 stall converter
Twin walbros w/780cc injectors
SAFC
29PSI

I am still running the very restrictive MAF, which I believe is holding me back as I added 6 psi of boost and only picked up 55 or so whp. Next time out I will have the MAP ECU and we’ll actually be able to see what the gains are. A/F’s were in the 11.9-12.1 range-a little leaner then I would like, but still pretty safe on a turbo this size and running straight C16.

I do like the flat hp/torque curves and it should be good for some mid/low 10s considering the weight of my car.

Let me know your thoughts.

Steve K.

 

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turbo....................
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1,057 Posts
nice numbers. how much does ur car weigh?
and this run was at 6psi?

thanks
 

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Administrator
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17,259 Posts
Looks like crazy MAF restriction based on that amazing "leveling off" of your graph! ;)

Steve T.
 

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Boost Junkie
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12,692 Posts
Discussion Starter · #4 ·
I'd agree, but I think the leveling off is more from the torque converter slipping on the top end. Here is a comparison of my 23psi vs 29psi pulls. I still think I am sacrificing some nice power though with the MAF. Once I get the MAP ECU on I will head back and post a direct comparison for everyone's benefit.

Steve K.

 

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Hey Steve,

Sorry I couldn't go to the dyno to see your car un. I'm still in San Antonio this week for work. Looks like your car is coming along well. I'd be very interested in seeing the new dyno graph when you get the MAP ECU installed and tuned. Anyway, looking good so far.
 

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Steve,
Thanks for posting that. Thae 23lb pull is really of interest to me. I
am hoping to be able to run 23lbs with my setup with the meth and
wondered what type of power through the PI3800 and stock maf I
could expect. Great info.
Wayne
 

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Inline for the win
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4,770 Posts
Talked about consistent and smooth. Nicely done. Now get that MAP ECU so you can make the engine fully shine with all your bling....

J/K....

DP
 

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Administrator
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Good call! I'm not accustomed to thinking about automatic transmission stuff, but I suppose it's akin to a slipping clutch! :lol:

Steve T.

Evill Supra said:
I'd agree, but I think the leveling off is more from the torque converter slipping on the top end. Here is a comparison of my 23psi vs 29psi pulls. I still think I am sacrificing some nice power though with the MAF. Once I get the MAP ECU on I will head back and post a direct comparison for everyone's benefit.

Steve K.

 

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Boost Junkie
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12,692 Posts
Discussion Starter · #10 ·
Wow,

Thanks for that information. I guess the 400 eats up more power than the Toyo trans so that makes sense. Overall I am very pleased with the power and driveability of this set up. High stall vs. stock stall, my car is making over 100whp more at 95mph with this set up.

Steve K.
 

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Toyotally Awesome
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647 Posts
Evill Supra said:
Wow,

Thanks for that information. I guess the 400 eats up more power than the Toyo trans so that makes sense. Overall I am very pleased with the power and driveability of this set up. High stall vs. stock stall, my car is making over 100whp more at 95mph with this set up.

Steve K.
I have a mildly loose converter so one would expect.... ~ 4500 rpms. The third gear in the TH400 is 1:1 and that's what I dynoed on.

I forgot to mention, I have an N/A-T which is somewhat apples to oranges, but not in the sense of a smaller turbo. I have the 3mm hg (so dang near static compression as a TT) and a bigger fuel system than you.
 

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Shawn Davis
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Is it just me misreading this or is there something wrong with the charts? With flat torque like that you should have increasing hp.
 

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Boost Junkie
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12,692 Posts
Discussion Starter · #13 ·
Not with a high stall converter and you are reading mph, not RPM. I learned a lot by comparing my old graphs to this set up. With the stock stall my car made peak power at 120mph and the graph got there gradually, just like with a manual clutch car.

With the high stall you make almost instant boost and the converter brings the power online. It then slips from 5500-7000rpms creating the flat power curve you see above. I am going to post my other graphs later tonight and you'll see the difference. This is another reason that autos are so much better for drag racing. You use more average power through the 1/4 mile when compared to 6-speed cars that have more of a ramping power curve and more gear changes.

Another interesting tid bit is I lost 10mph in 3rd gear at the same rpms because of the slipping converter. This is completely normal and I will gladly sacrifice this if it means bettering my ET.

Steve K.
 

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Steve,

Have you ran your car down the 1/4 mile yet with your current setup? Just curious what you are running at this level.
 

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Boost Junkie
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Discussion Starter · #15 ·
Robby,

Not yet. I really need to convert it to speed density...either that or route my BOV(s) back to the turbo inlet because I can't do a burnout now with the atmospheric BOV(s) because of the MAF. The car just dies. It should do mid 10s pretty easily though once is all said and done. Prolly run it in the fall time.


Steve K.
 

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Hey there Steve K.

Could I ask you what brand your camshafts are and do they let you idle nicely?

Just curious,

Thanks
Marc
 

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Evill Supra said:
Not with a high stall converter and you are reading mph, not RPM. I learned a lot by comparing my old graphs to this set up. With the stock stall my car made peak power at 120mph and the graph got there gradually, just like with a manual clutch car.

With the high stall you make almost instant boost and the converter brings the power online. It then slips from 5500-7000rpms creating the flat power curve you see above. I am going to post my other graphs later tonight and you'll see the difference. This is another reason that autos are so much better for drag racing. You use more average power through the 1/4 mile when compared to 6-speed cars that have more of a ramping power curve and more gear changes.

Another interesting tid bit is I lost 10mph in 3rd gear at the same rpms because of the slipping converter. This is completely normal and I will gladly sacrifice this if it means bettering my ET.

Steve K.
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Yeah, that's why I think the mph graph is more infomative than rpm
for high stall cars. If you plot rpm everyone says "wow, look at all the
lag" not understanding the way a higher stall car behaves.
Wayne
 

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Shawn Davis
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1,662 Posts
Evill Supra said:
Not with a high stall converter and you are reading mph, not RPM. I learned a lot by comparing my old graphs to this set up. With the stock stall my car made peak power at 120mph and the graph got there gradually, just like with a manual clutch car.

With the high stall you make almost instant boost and the converter brings the power online. It then slips from 5500-7000rpms creating the flat power curve you see above. I am going to post my other graphs later tonight and you'll see the difference. This is another reason that autos are so much better for drag racing. You use more average power through the 1/4 mile when compared to 6-speed cars that have more of a ramping power curve and more gear changes.

Another interesting tid bit is I lost 10mph in 3rd gear at the same rpms because of the slipping converter. This is completely normal and I will gladly sacrifice this if it means bettering my ET.

Steve K.
Obviously there is a direct link between the speed and the rpm (just the gear ratio conversion) so I don't think that's a factor.

Your suggestion that its a function of the high stall torque convertor would explain the loss of overall speed, but doesn't really explain the flat horsepower band to me (I may just be dense). Since hp is a direct function of torque, and is calculated by the dyno from the torque measurement, a flat torque curve necessarily has to generate an increasing hp curve. So just for the sake of argument let's say you were making about 450 ft-lb at 5000 rpm and 400 ft-lb at 7000 rpm (looks rough right from your plot). That would suggest your power should ramp from 380 hp to 460 hp between those points. Instead it's flat at at 500 hp....

Just trying to understand here...

PS--Why would a flat hp curve be a benefit? A flat torque curve is a benefit in road racing for the sake of control and throttle modulation, but to me a flat hp curve just means you should shift earlier to get into a higher gear. If you're making the same hp at 5000 rpm as 7000 rpm, you may as well be getting the mechanical gearing advantage to increase your speed.
 

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Ubermensch
But the "direct" relationship between rpm and mph does
not really apply here. My car shifts from 2nd to drive at
about 75mph and is at 6200+ rpm immediately after the
shift. At 7k rpm(on tack) my speed is ~122mph. 800 rpm
in driv,e is not equal to 47 mph. The relationship between
rpm and mph is not close to linear. I am not sure about
the why's of this. Only that this is the way the car behaves.

Steve,
How were you not maxing out the maf signal well before 29lbs?
Are you sure that boost number is accurate?
Wayne
 

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Boost Junkie
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Discussion Starter · #20 ·
Of course it is. I have 2 boost gauges, one greddy and one blitz on the boost controller.

Keep in mind I have a fuel system and take out 22% of fuel on the top end. The MAF was seeing 5 volts, however, since I had 22% of the fuel removed from the factory MAF map, I am able to support well over what the stock fuel system is set up for. The cool thing is that I drove the car back and forth to Indy about 2 weeks ago and got over 25mpg on the highway at a steady 80-85mph. Pretty damn good for a car with a high stall converter. I was able to do this because the MAF meters the air so much better than you can with speed density.

Steve K.
 
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