Strange loss of power after intercooler install - can't explain
12-05-2009, 08:12 PM
#1
Strange loss of power after intercooler install - can't explain I faced some unexplainable (for now) problem. I have 383ci with mild cam, 9.2:1 CR, and TC78 at 8psi. Before installing intercooler, I measured max of 410whp. Intake temperatures were at 160-180 after a single run ir 2nd or 3rd gear.
Now, I installed 4" intercooler, with 3" piping. Temps are only about 6-12 degrees above ambient, which I think is quite OK. The problem is, now I get only about 360whp, with 8psi (measured at the outlet of turbo).
AFR is at 12.4-12.6, timing wise - tried from 12 to 17 degrees with no measurable gains.
What could be the reason for such power loss??
Now, I installed 4" intercooler, with 3" piping. Temps are only about 6-12 degrees above ambient, which I think is quite OK. The problem is, now I get only about 360whp, with 8psi (measured at the outlet of turbo).
AFR is at 12.4-12.6, timing wise - tried from 12 to 17 degrees with no measurable gains.
What could be the reason for such power loss??
12-05-2009, 08:45 PM
#4
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I don't think your seeing a power loss, you need to measure boost at the intake manifold. With the intercooler restriction and the cooler air you are seeing less boost at the intake manifold. Turn the boost up so your seeing 8lbs at the motor.
12-05-2009, 09:05 PM
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That would be my guess. I had a 7 lb. loss at the intercooler when I first dyno'd my set up. pullied to about 21lbs but was only seeign 13.5 at the manifold.
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12-05-2009, 10:29 PM
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What kind of intercooler?
What kind of kit?
What kind of gas?
Where is your boost/vacuum source?
1. Your A/F is waaay to lean even for a badass bottom end.
2. 17 degrees is way too much timing unless youre running methanol, e85, or something comprable.
3. Who is your tuner? Because I would punch him.
What kind of kit?
What kind of gas?
Where is your boost/vacuum source?
1. Your A/F is waaay to lean even for a badass bottom end.
2. 17 degrees is way too much timing unless youre running methanol, e85, or something comprable.
3. Who is your tuner? Because I would punch him.
12-06-2009, 08:15 AM
#10
But where on the intake I can measure pressure? The only suitable spot I see is this thing after throttle body - what is this?
Last edited by Vetal; 12-06-2009 at 08:26 AM.
12-06-2009, 08:20 AM
#11
What kind of intercooler?
What kind of kit?
What kind of gas?
Where is your boost/vacuum source?
1. Your A/F is waaay to lean even for a badass bottom end.
2. 17 degrees is way too much timing unless youre running methanol, e85, or something comprable.
3. Who is your tuner? Because I would punch him.
What kind of kit?
What kind of gas?
Where is your boost/vacuum source?
1. Your A/F is waaay to lean even for a badass bottom end.
2. 17 degrees is way too much timing unless youre running methanol, e85, or something comprable.
3. Who is your tuner? Because I would punch him.
What kit?
Just your usual gas from the gas station
at the outlet of the turbo, like I said
AFR is OK
Timing - as I already wrote, I started from 11-12deg at the top. Can't see how even 17deg is way too much even at 8psi, minus the pressure drop
I am my tuner, I won't do that for now.
12-06-2009, 09:49 AM
#13
If you really think a middle 12 AFR at WOT with a boosted setup is "OK" then you should fire your tuner.
You always want to take your boost/vacuum readings from the intake manifold because that's what most closely represents the actual aircharge making it to the cylinders. You are flying blindfolded if you reference your boost from anywhere before that, especially at the turbo. Size of boost tubing, transitions in diameter, transitions in direction, how those size and direction transitions are made, faulty BOV, IC, MAFS, TB are all items that can possibly skew your boost reading depending on the situation. To eliminate these items becoming factors in what gives you a reliable boost reading it is best to pull your signal after all of these. Good luck with your issues.
12-06-2009, 10:22 AM
#14
As I said, at this point I just don't know where to get manifold pressure reading from. That port after throttle body attracts my attention, but I don't know what it is...
Those who think AFR of 12.5 is very lean for 6-7psi, care to explain how am I making 22psi for a few years now with this AFR? Thing is, you don't have to dump tons of fuel in a low-comp, low-boosted engine, as it is in this case
Those who think AFR of 12.5 is very lean for 6-7psi, care to explain how am I making 22psi for a few years now with this AFR? Thing is, you don't have to dump tons of fuel in a low-comp, low-boosted engine, as it is in this case
12-06-2009, 10:35 AM
#15
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Two places to tap into, there is a place on the back of the manifold by the map sensor that you can T into that line or get a T fitting and splice into the power brake booster line. Are you running a BOV?
Run your afr 10.5-11.5 bring your timing back to about 13 degrees while your troubleshooting. You might be able to run more depending on the quality of your gas. What octane gas can you get there?
So the bottom line is there probably isn't a actual power loss but you need to work on a few items.
Run your afr 10.5-11.5 bring your timing back to about 13 degrees while your troubleshooting. You might be able to run more depending on the quality of your gas. What octane gas can you get there?
So the bottom line is there probably isn't a actual power loss but you need to work on a few items.
Last edited by mike13; 12-06-2009 at 10:44 AM.
12-06-2009, 11:04 AM
#16
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I like keeping my turbo cars around 11.5-11.8 AFR. Anything richer and plugs foul quickly and dont usually see any gains from it. Most or all gains is associated with the timing majority of the time. I dont doubt your tuning skills since your making 360hp on a CA18 but maybe richen the AFR to just under 12.0 and adjust timing from there. Also post up a dynograph if you could. If its timing related, its usually shown in the tq curve.
12-06-2009, 12:37 PM
#18
Does brake booster see positive pressure too? Isn't there some one-way valve?
Run your afr 10.5-11.5 bring your timing back to about 13 degrees while your troubleshooting. You might be able to run more depending on the quality of your gas. What octane gas can you get there?
So the bottom line is there probably isn't a actual power loss but you need to work on a few items.
So the bottom line is there probably isn't a actual power loss but you need to work on a few items.
Yepp, need to know pressure in manifold, without that I'm basically blind now.
One more thing - torque peak is still at 3600rpm with about 400lb, like it was before the IC. It looks like something is choking flow at the top, and the only thing that could do this is IC, since nothing else changed. I don't think 3" pipes are at fault at this power level
12-06-2009, 01:25 PM
#19
For your boost reference, go to MC Master Carr and get a manifold log. You install it inline with your brake booster hose.
As far as your tune, I would think your timing is ok since you are only running low boost. I ran that much up to 20psi. Your A/F is a little leaner than I would like, BUT since you are low boost, I would think your fine there. Any more and you would need to add some fuel. Your intercooler is OK. Guys have gone 8's with that intercooler.
As far as your tune, I would think your timing is ok since you are only running low boost. I ran that much up to 20psi. Your A/F is a little leaner than I would like, BUT since you are low boost, I would think your fine there. Any more and you would need to add some fuel. Your intercooler is OK. Guys have gone 8's with that intercooler.
12-06-2009, 01:46 PM
#20
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Don't even worry about your horsepower until you are running 8lbs at the intake manifold. I think your horsepower numbers will be better than before the intercooler install.