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Old 05-09-2014, 06:46 PM   #1
turbotankshane
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Default Dyno sheets. What next?




Made a trip to the dyno today. The red graph is from about a year ago, car was at 300K with just 2.5" exhaust. Blue graph is from today with same exhaust, gutted airbox/k&n with extra cold air pipe routed to front bumper, 15g @ 12psi, IPD cam @ +2.5, TLAO chips.
It was nice to verify a decent gain by other means than butt dyno. Made a few pulls, in 2nd and 3rd, 2nd gear was used for the graph shown.
I noticed on the dyno I seemed to get a backfire right as boost peaks, but AFRs were perfect the entire time, so it leads me to think timing may be too advanced? I have no way to mess with the tune right now, just looking for input.
I'm looking to get a 250+hp setup from this car. I don't really like the way the power is falling after 5k, so I may run the cam straight up soon and see if it helps. I'm sure the stock downpipe is choking flow as well, so I plan to get a new 2.5" dp made to match diameter of the rest of the exhaust.
So current plans include 2.5" dp, bigger intercooler, and I have a 4bar fpr ready to go in and plan to run 15psi. Think this should reach my goals?
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Old 05-09-2014, 07:08 PM   #2
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What it looks like to me,

Your wastgate allowed a little over boost notice the spike at the start then a drop. Notice a spike in the a/f ratio at the same time? You caused a momentary lean condition at that point. Not major, what boost controler are you using?

Always start tuning a car with stock cam timing. With the amount of smoothing and the choppiness of the graph, you may be have some issue in the cam set up or spark plugs getting blown out. A good a/f ratio does not always dictate no knock. Check the plugs for signs of pinging. Small pepper specks on the plugs.

Something else to add, if I remember right, the distributor on the 740 is attached to the back of the cam. When you changed the cam timing, did you reset the ignition timing? This is over looked often on these time of set ups. You advance the cam timing and advance the ignition as well(correct me if I am wrong on this could be retarding it)

You have a good set up. A little fine tuning will do wonders before throwing more parts at it.
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Old 05-09-2014, 07:16 PM   #3
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Do not waste your time with a 2.5" exhaust.

Go 3" on the downpipe and cat (if you ar egoing to run a cat) from there you can stay 2.5" exhaust but 3" is recommended.

An intercooler will help a ton also over the entire powerband.

No need for more fuel just yet as you are still plenty rich under load.

3" downpipe, NPR or Ebay IC and turn the boost up to 16psi. Those alone should put you near 200whp.
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Old 05-09-2014, 07:31 PM   #4
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Did you port the exhaust manifold outlet when you swapped turbos?

Looks kind of like my dyno "curves" when I had a bad head gasket- check compression lately at 300+K?
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Old 05-10-2014, 09:57 AM   #5
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Originally Posted by thelostartof View Post
Do not waste your time with a 2.5" exhaust.

Go 3" on the downpipe and cat (if you ar egoing to run a cat) from there you can stay 2.5" exhaust but 3" is recommended.

An intercooler will help a ton also over the entire powerband.

No need for more fuel just yet as you are still plenty rich under load.

3" downpipe, NPR or Ebay IC and turn the boost up to 16psi. Those alone should put you near 200whp.
+1

The down pipe is where the exhaust is still extremely hot so the extra volume will allow for better evacuation.
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Old 05-10-2014, 12:07 PM   #6
turbotankshane
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Originally Posted by midnightsaint View Post
What it looks like to me,

Your wastgate allowed a little over boost notice the spike at the start then a drop. Notice a spike in the a/f ratio at the same time? You caused a momentary lean condition at that point. Not major, what boost controler are you using?

Always start tuning a car with stock cam timing. With the amount of smoothing and the choppiness of the graph, you may be have some issue in the cam set up or spark plugs getting blown out. A good a/f ratio does not always dictate no knock. Check the plugs for signs of pinging. Small pepper specks on the plugs.

Something else to add, if I remember right, the distributor on the 740 is attached to the back of the cam. When you changed the cam timing, did you reset the ignition timing? This is over looked often on these time of set ups. You advance the cam timing and advance the ignition as well(correct me if I am wrong on this could be retarding it)

You have a good set up. A little fine tuning will do wonders before throwing more parts at it.
Hmm. I see that spike on the curve now. I think I'm going to run the cam straight up and see if it helps. I think the cam being advanced, paired with the advanced timing of the chips, may be causing spark blow out. I'm using bpr7es plugs set to factory gap, with fairly new wires, rotor/cap and coil, so I know plugs are up to the task. If that doesn't help I may just try a little bigger gap on the plugs.
I was under the impression that the EZK controlled ignition timing advance, so I don't believe I advanced ignition timing when I advanced cam timing.
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Old 05-10-2014, 12:14 PM   #7
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Did you port the exhaust manifold outlet when you swapped turbos?

Looks kind of like my dyno "curves" when I had a bad head gasket- check compression lately at 300+K?
I did no porting when I swapped the turbos. I'm thinking I will soon because my manifold has developed a small crack.
I checked compression around the time the first curve was made. Cyl #3 was a little weaker than the rest but still within spec. Other three were great. The car now has 311k and hasn't been beat on daily so I think compression should still be good.
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Old 05-10-2014, 12:15 PM   #8
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Originally Posted by thelostartof View Post
Do not waste your time with a 2.5" exhaust.

Go 3" on the downpipe and cat (if you ar egoing to run a cat) from there you can stay 2.5" exhaust but 3" is recommended.

An intercooler will help a ton also over the entire powerband.

No need for more fuel just yet as you are still plenty rich under load.

3" downpipe, NPR or Ebay IC and turn the boost up to 16psi. Those alone should put you near 200whp.
3" pipes and intercooler are next on the to do list.
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Old 05-10-2014, 01:11 PM   #9
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You may want to check everything make sure its not off a tooth or leaking boost or anything. This is my dyno pull lh2.4 no chips +3 ignition mod with stock downpipe, ebay ic, and 2.5 side exhaust. 15g on 16lbs. So no chips or cam but I made more power still blowing black smoke Cause it was so dang rich. That was done with a blown head gasket
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Old 05-10-2014, 02:52 PM   #10
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What condition is the aw71 in?
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Old 05-10-2014, 03:35 PM   #11
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What condition is the aw71 in?
Good condition. It doesn't get launched a lot, gets maintained religiously and shifts perfectly with no modifications.
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Old 05-10-2014, 07:49 PM   #12
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You may want to check everything make sure its not off a tooth or leaking boost or anything. This is my dyno pull lh2.4 no chips +3 ignition mod with stock downpipe, ebay ic, and 2.5 side exhaust. 15g on 16lbs. So no chips or cam but I made more power still blowing black smoke Cause it was so dang rich. That was done with a blown head gasket
What cam was that with?
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Old 05-10-2014, 09:47 PM   #13
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3" pipes and intercooler are next on the to do list.
Why 3" intercooler piping? Its over kill to say the least. The thing is the turbo has to fill the volume of the intercooler and the piping and larger diameter piping with a small compressor hurts the air velocity. Use 2.5" piping to keep the velocity up. I have seen cars with over 500awhp do just fine with 2.5" tubing. The only advantage of 3" over 2.5" is if there is a bunch of tight radius bends.


My other car is 1999 A4 with a gt3071r and I run 2.25" hotside of Intercooler and 2.5" coldside. Never an issue.

Last edited by zandrew; 05-10-2014 at 09:54 PM..
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Old 05-10-2014, 10:33 PM   #14
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The 3" intercooler plumbing isn't going to hurt anything, it will only help. You won't feel a difference in the time it takes to pressurize that volume, and it's not going to hurt velocity.
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Old 05-10-2014, 10:44 PM   #15
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Why 3" intercooler piping? Its over kill to say the least. The thing is the turbo has to fill the volume of the intercooler and the piping and larger diameter piping with a small compressor hurts the air velocity. Use 2.5" piping to keep the velocity up. I have seen cars with over 500awhp do just fine with 2.5" tubing. The only advantage of 3" over 2.5" is if there is a bunch of tight radius bends.


My other car is 1999 A4 with a gt3071r and I run 2.25" hotside of Intercooler and 2.5" coldside. Never an issue.
My communication skills are getting worse. I meant 3" exhaust, or at least 3" downpipe, and an upgraded intercooler are next on the list.
However, since you planted the idea, I guess upgrading the tubing should be in order as well. Where's the best place to order bigger intercooler piping?
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Old 05-11-2014, 10:10 AM   #16
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My communication skills are getting worse. I meant 3" exhaust, or at least 3" downpipe, and an upgraded intercooler are next on the list.
However, since you planted the idea, I guess upgrading the tubing should be in order as well. Where's the best place to order bigger intercooler piping?
http://www.siliconeintakes.com/
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Old 05-11-2014, 11:15 AM   #17
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What cam was that with?
Stock t cam and stock cam gear. Ported manifold and exh housing but im not sure its worth that much power.
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Old 05-11-2014, 01:48 PM   #18
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The 3" intercooler plumbing isn't going to hurt anything, it will only help. You won't feel a difference in the time it takes to pressurize that volume, and it's not going to hurt velocity.
Have you actually tried this? I have and the first thing I will tell you is my gt3071r spools faster then several gt2871r builds on the exact same engine. I am actually using the odd ball gt3071r wg version with .86 housing and 90 trim turbine and I am still doing better then others with the same tune and I am using 2.5" exhaust to their 3" exhaust.

Any amount of air forced through a smaller pipe compared to a bigger pipe will have a greater velocity as long as the pipe is not to small to cause a restriction. The tircks with intercooler piping is to use the shortest amount possible and the smallest size possible without causing a restriction.

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Old 05-11-2014, 01:59 PM   #19
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My communication skills are getting worse. I meant 3" exhaust, or at least 3" downpipe, and an upgraded intercooler are next on the list.
However, since you planted the idea, I guess upgrading the tubing should be in order as well. Where's the best place to order bigger intercooler piping?
On DP and exhaust you want either the same size dp and exhaust or a larger dp then exhaust. The exhaust gas at the DP is extremely hot and will need area to expand back too post turbine. It cools considerable from the DP to exhaust.
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Old 05-11-2014, 02:07 PM   #20
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Stock t cam and stock cam gear. Ported manifold and exh housing but im not sure its worth that much power.
I'm sure it's worth a little bit on the top end. And I see the same spike on your curve as boost comes on, maybe it's the hallman boost controller i'm using.
I think running the cam straight up and with the extra flow/reduced pressure drop from a better intercooler, I should see a lot better performance.
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Old 05-17-2014, 09:41 AM   #21
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Forcing air through smaller piping raises the temperature of the whole turbo system...that's why bigger pipes are beneficial they don't create more heat and they shed more heats thanks the fact the larger pipes having more area to displace heat.

Yes you can run smaller pipes and get same results....the real difference is cost....smaller pipes cost less so that's why most pay less for them......but those that understand what's happening pay more fore biggest pipes they can get cuz the benefits of the bigger pipes outweighs the small diameter pipe
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Old 05-17-2014, 05:34 PM   #22
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Finally got around to taking the IPD gear off and timing the cam straight up. Reset LH and only got to put 30 miles on it so far, but I can tell a huge difference already. The lean patch has setlled down on me, power curve is much more linear. The butt dyno can't tell any loss in low end torque, but power on the high end is much better. Overall feels much smoother and is definitely an improvement for the current setup.
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Old 05-17-2014, 07:32 PM   #23
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Sweet now sell me your cam gear lol
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Old 05-17-2014, 07:50 PM   #24
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Sweet now sell me your cam gear lol
Just posted it for sale today!
http://forums.turbobricks.com/showthread.php?t=295396
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Old 05-17-2014, 08:44 PM   #25
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Forcing air through smaller piping raises the temperature of the whole turbo system...that's why bigger pipes are beneficial they don't create more heat and they shed more heats thanks the fact the larger pipes having more area to displace heat.

Yes you can run smaller pipes and get same results....the real difference is cost....smaller pipes cost less so that's why most pay less for them......but those that understand what's happening pay more fore biggest pipes they can get cuz the benefits of the bigger pipes outweighs the small diameter pipe
You have lost your mind. I did an exact test on difference of small intercooler piping and large intercooler piping with IAT and there is absolutely no difference in temp if the piping will support the flow as I already told you. Yes if you are trying to force 40lb min of flow through 1.5" intercooler piping its going to heat it up. However 2.5" has been proven to be more then ample for over 500AWHP and 3" is OVER KILL!!! (hell I know a car that is running close to 700AWHP with 2.5" but I guess he cut cost right?) I did this test back about 8 years ago and I will try to find it for you.

These cars run small compressor with tiny exducer which is what accelerates the air outward from the compressor housing. Since the compressor exducer is so small you have to spin the absolute **** out of them to make boost. The accelration will be reduced significantly when going into an oversized pipe and the acceleration is needed to carry through the intercooler and into intake system. Slowing down the flow will result in loss of spool and performance.

The piping does not wick away heat as you are suggesting. The intercooler does. The point is to get the charged air into the intercooler as quickly as possible. Why is it that aluminum is used anyway for intercooler piping? For the exact same reason it is used in Soda can.

Honestly if we followed your example all I would have to do is run 20 feet 4" intercooler piping and no intercooler since that would have the same surface area right?

Use the smallest intercooler piping that does not choke flow of the compressor. If you don't believe me take a straw blow into it. Then take a radiator hose and do the same. Then think of how fast the piston is moving up and down and you will see why it is important to have proper inlet velocity which also atomizes the fuel better.

The difference between 3" and 2" or 2.5" is that if I run 2" the next fool always wants to be bigger since they think its better. Has nothing to do with cost. Honestly I have $7,000 in my engine alone. Do you really think I would skimp on intercooler piping to save maybe $20 at the most?
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