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Old 11-14-2013, 04:01 PM   #251
Scargod
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Quote:
Originally Posted by kellygnsd View Post
If the scales for Hp and TQ aren't the same the graph will never cross at 5250. There is nothing wrong with the FAST plot.
WRONG! When measuring foot pounds of torque and standard horsepower, the unit conversion causes the two curves to intersect at 5250 rpm. Always.
If you are plotting relative to RPM, as is normal, it doesn't make a damn how you have the torque and horsepower scaled or which side they're on. If they are not typical they'll look a little odd, but they'll still cross at 5250 RPMs.
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Old 11-14-2013, 05:05 PM   #252
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Quote:
Originally Posted by kellygnsd View Post
The values of torque and HP should be the same at 5250 rpm but if both Y axis aren't scaled the same your physical lines won't intersect there. If you still think that it should I suggest you take a mid level math course.
Another interesting thing about that graph is the fact that only the Hp is SAE corrected and the TQ is not. Because of that the Hp is a tad higher than the TQ at that rpm proportional to the correction factor applied.

Look at the graphs again and you'll see @ 5250 TQ is ~400 ft-lb and Hp is about 412.5 Hp SAE corrected. I wish the actual correction factor was printed on the graph but I'm going to go out on a limb and say it was probably around 3.75% which is a totally believable SAE correction factor. 400Hp + 3.125% C.F. = ~412.5 Hp SAE corrected and is not too far fetched.
EDIT: changed correction factor

Last edited by kellygnsd; 11-15-2013 at 09:44 PM. Reason: Caluculated actual CR, changed values from 415 to 412.5
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Old 11-14-2013, 06:09 PM   #253
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They don't always cross at 5252 on all dynos, that's all I can really say.

Kelly's logic is sound, it must be the scaling at which the tq is converted to read hp.
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Old 11-14-2013, 06:17 PM   #254
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Quote:
Originally Posted by kellygnsd View Post
The values of torque and HP should be the same at 5250 rpm but if both Y axis aren't scaled the same your physical lines won't intersect there. If you still think that it should I suggest you take a mid level math course.
Another interesting thing about that graph is the fact that only the Hp is SAE corrected and the TQ is not. Because of that the Hp is a tad higher than the TQ at that rpm proportional to the correction factor applied.

Look at the graphs again and you'll see @ 5250 TQ is ~400 ft-lb and Hp is about 415 Hp SAE corrected. I wish the actual correction factor was printed on the graph but I'm going to go out on a limb and say it was probably around 3.75% which is a totally believable SAE correction factor. 400Hp + 3.75% C.F. = ~415 Hp SAE corrected and is not too far fetched.
You beat me to it. You're right on the money. Graphed lines will certainly not cross at 5250 RPM with the scale on both torque and HP being unequal. SAE correction is absolutely the reason for the numerical discrepancy. If you would like I can post the dyno data which shows torque, hp and SAE hp, but I think we've covered this in past threads enough times.

-Hill
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Old 11-15-2013, 01:27 AM   #255
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Quote:
Originally Posted by Full-Race Geoff View Post
thanks a lot - you make a good point that 79lb/min is a lot of airflow!! With twinscroll and gamma-ti, spool is rarely the issue - now its become more a matter of matching the right powerband/turbo to the driver/engine. I will say after 2 years on my 8374 2.0L evo i want to try 7670 or 7163 next



last thing to add - heres another 8374 subaru dyno chart: http://forums.nasioc.com/forums/showpost.php?p=40795401&postcount=73 in case you hadnt seen it
thanks Geoff for the link
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Old 11-15-2013, 07:12 PM   #256
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Quote:
Originally Posted by kellygnsd View Post
The values of torque and HP should be the same at 5250 rpm but if both Y axis aren't scaled the same your physical lines won't intersect there. If you still think that it should I suggest you take a mid level math course.
Another interesting thing about that graph is the fact that only the Hp is SAE corrected and the TQ is not. Because of that the Hp is a tad higher than the TQ and that rpm proportional to the correction factor applied.

Look at the graphs again and you'll see @ 5250 TQ is ~400 ft-lb and Hp is about 415 Hp SAE corrected. I wish the actual correction factor was printed on the graph but I'm going to go out on a limb and say it was probably around 3.75% which is a totally believable SAE correction factor.
I'm referring to only one graph; the one in post 235. I'm not suggesting hanky-panky, but it doesn't make sense. Some 600 RPMs off? Measurements on this graph are in common units (not metric, etc).
There are lots of articles out there like this.
You can insult me, but you can't change facts.
NOTE: Sorry if I caused a fuss about nothing. It's just that correcting HP on the chart isn't something you see everyday, and I've not seen it before. I accept kellygnsd explanation and apologize for being so thick about the scaling of HP related to torque. While I was composing this post (and unknown to me at the time), Hill came in and explained, which is what I wanted in the first place; for the tuner or Coop to explain.

Last edited by Scargod; 11-16-2013 at 09:07 AM. Reason: Added note
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Old 11-15-2013, 08:30 PM   #257
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Let's do an exercise.
1. Pick any rpm on that chart from post 235
2. Multiply that TQ by the rpm then divide by 5250. This = uncorrected Hp
3. Multiply that # by 1.03125 to get SAE corrected Hp
4. Compare that to the Hp on the chart and tell me where they are not equal.

What you're failing to understand is how by changing the scale of either Hp or TQ in relation to the other you can make the two plots cross at whatever rpm you want. Just because the lines don't cross at 5250 doesn't mean the value of TQ and Hp aren't the same at 5250. It's all about looking at the right scale.
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Old 11-16-2013, 03:30 AM   #258
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#1 do not be sorry for hijacking this thread (forget who it was) this is posted on here to educate all about this setup

#2 i think I would really like to test this thing on E85. Hill, can I get away w using the 1300cc injectors since everything else is preset to run E85?

Just thought id keep the updates coming. Trying to get to track in next few weeks to see how it does
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Old 11-16-2013, 05:30 AM   #259
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i read the last page and immediately knew it had to do with a dynapack dyno without even looking at the graphs. i personally hate how they do that but at least they give you a way to convert it to a standard style graph (ie. 5252 intersect with equal scaling.) i asked for my graph that way when i had my car tuned.
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Old 11-16-2013, 08:05 AM   #260
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Quote:
Originally Posted by Coop1103 View Post
I would really like to test this thing on E85. Hill, can I get away w using the 1300cc injectors since everything else is preset to run E85?
E85 works wonders, especially on these turbos. The increase in burned fuel mass and exhaust mass flow rates only helps the turbine. 1300cc injectors are not huge but should be OK for E85, however you will need (2) fuel pumps, just add a walbro E85 pump (walbro 416) next to whatever fp you have now and run it on a hobbs switchh
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Old 11-16-2013, 12:12 PM   #261
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After my sucking the oxygen out of the thread for a while I am asking, with humility, if the 1300 cc/min injectors are really enough for e85? I expressed concern about you running 25 PSI with pump gas and that was with 1000 cc injectors, correct? I was told to run 100 octane with my 24.2 PSI boost.
For my 8374 build I went with ID 2000s. I did some research on injectors and didn't find what I wanted after 1300s; thinking 1300cc/m a little marginal for a conservative <40 PSI fuel pressure (I am at 38 now). I tried to look at duty cycles at or below 80% while considering the GPM consumption for a 600 hp motor. I bought a Bosch 044 and various electrical pieces to give me the added fuel when I need it vs recirculating the fuel like mad. I think I will be OK if I choose to try E85. Not sure if I want to drag around a 55 gallon drum. But I digress...

Now, you are looking at using E85 which is a 30% boost in GPM. I defer to Geoff, but 1300s seem small.
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Old 11-16-2013, 12:43 PM   #262
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1300cc ID's would be on the small side for this application. There's no question what we would run out of injector before this setup would be maxed out. It's really all about how much fuel pressure (within reason) you can get away with given your fuel pump setup and how much boost you want to run. I like 2000cc ID's for high hp applications like this one.

-Hill
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Old 11-16-2013, 09:40 PM   #263
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The ID1300's should get Coop to 600-650+WHP on E85. Especially if he can bump the base pressure up and if the pump can keep pace as Hill stated. I don't think you would want to push those bored out jugs much beyond the 600 mark and only on e85 or race gas.

I'm just finishing some fortification on the fuel supply side with a KB BAP and wiring so that my Walbro 465 can better do its job with my ID1300's. I'm at 50psi base as I think that's all I need for now with my build.

~Allan

Last edited by manitou; 11-17-2013 at 11:49 AM.
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Old 08-15-2014, 02:14 AM   #264
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Any updates?
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Old 09-01-2014, 01:57 PM   #265
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Meth...sorry i just saw this post. It is still my daily driver on the 1300cc injectors. Still rips hard and it almost has 100k miles on it. Just coming to a point where I am bored and want a c5 z06 for something different to work on. Its been for sale for a while but no bites. Many do not understand whatbthis car is about! Ha. Ill keep it as my dd till it sells cause it sure is fun. It still turns heads and is very respected as the top sti in my area. You cant go wrong with this setup. Only downfall.....very loud. I feel bad for my neighbors. ��
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Old 09-01-2014, 02:05 PM   #266
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Thanks for the updates. We are about to install the fuel system, -8an PTFE feed lines, -6an return, dual in tank Walbro 465 lph pumps, 2nd activated by AEM series 2, flex fuel sensor. My 8374 efr build will be dual Tial 38mm external wastegates.


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Last edited by methaddict; 09-01-2014 at 02:36 PM.
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