[BLOWN64]

I HAVE ONE PROBLEM AND I HOPE SOMEONE HAS AN ANSWER. I HAVE A P1-SC PROCHARGER BLOW THROUGH CARB. TYPE AND WHEN IT IS CONNECTED STRAIGHT TO THE CARB IT RUNS FINE BUT WHEN I CONNECT THE INTERCOOLER AND FLOOR IT . IT WANTS TO START TO BUCK, UNTIL I LET UP JUST BEARLY AND THEN ITS OK THEN FLOOR IT. BUCKING AGAIN, CAN ANYONE HELP IT IS FINE OFF THE LINE BUT WHEN IT STARTS TO BUCK I LOOK AT THE BOOST GAUGE AND IT READS 5 PSI AND WITH NON INTERCOOLED I GET 10 PSI NO PROBLEM.

[drlindz]

Turn off your CAPS.

I could be wrong, but it sounds like the intercooler is not allowing enough airflow.
What is the rated CFM of the intercooler?

[Magnum Rockwilder]

Check for boost leaks.

[BLOWN64]

Originally posted by drlindz
Turn off your CAPS.

I could be wrong, but it sounds like the intercooler is not allowing enough airflow.
What is the rated CFM of the intercooler?

I bought the intercooler off ebay and they told me that it was pressure tested to 25 lbs. Dont know the cfm but it is 29" long 12" wide and 4" thick could it be to big for my set up or just a bad intercooler.

Originally posted by Magnum Rockwilder
Check for boost leaks.

Dont know how to check for leaks do you need a certain tool to check.

[drlindz]

There are many considerations to take into account when choosing and setting up an inter-cooler.

I am far from an expert on this so I will not make an attempt to try and explain.We have some members that are experts and I am sure that one will be along shortly.

It would also help if you gave some more details on your setup.I seem to have misunderstood what you meant when you said that it starts to "buck". Explaining this more clearly could also help.

I hope that you can work this problem out soon.

[BLOWN64]

Originally posted by drlindz
There are many considerations to take into account when choosing and setting up an inter-cooler.

I am far from an expert on this so I will not make an attempt to try and explain.We have some members that are experts and I am sure that one will be along shortly.

It would also help if you gave some more details on your setup.I seem to have misunderstood what you meant when you said that it starts to "buck". Explaining this more clearly could also help.

I hope that you can work this problem out soon.

Iam running the prochargerwith 10 lbs of boost on a 355 cid with a holley 650 double pumper. when I floor the throttle its like its hesitating but only when the carb is at full throttle if i let up just a little it runs fine Iam thinking it is the pump shot but then again procharger told me it was the ignition so i got an msd 6al and it didnt help.

[gt2betubbed]

I'm no expert either, but since you're loosing boost only with the intercooler on, it sounds like you got a bum cooler off ebay. I'd have the cooler tested for leaks.

[BLOWN64]

Originally posted by gt2betubbed
I'm no expert either, but since you're loosing boost only with the intercooler on, it sounds like you got a bum cooler off ebay. I'd have the cooler tested for leaks.

I dont know if its losing boost because it starts to hesitate or buck before I can get the rpm's up it reads 5 lbs when it starts to buck or hesitate. I dont know if its the carb or having to do with cooler air meaning more dense means more air in and needing more gas

[TurboS10]

One of the probems with using a carb and boost is that it cannot react to air temperature. It sounds to me like when you are without the cooler, your carb is about right. When you add the cooler, you are getting a cooler, denser air charge which will need to be tuned for. Usually a cough or stumble is a lean condition, which would make sense for what you are telling use here.

I would also add that that cooler is really way to small. It is not to say it will not work, but you will be trying to overcome the pressure drop of the cooler along with the air velocity being so high throught the cooler it is not going to work properly. You have to realize that a pressure rating is not jack crap on a cooler. It should definately hold pressure, but cfm is what really counts. The tubes of an intercooler are stuffed full of fins that restrict flow to cause "intimate contact" with the cooler walls to increase cooling capacity. Most coolers on an engine of that size would be at least double that size for air-air. I am curious what the flow area is on the cooler. If it is flowing through the 12x4 inch area, which I suspect, you are choking it badly. If you read Corky Bell has a chart in his book Maximum boost to address cooler sizing. He shows a need for about 40 sqaure inches for 700 cfm. Your cooler if using the above config. is at 48 in. total before subtracting out all the area between the tubes which is probably about 40 percent. This puts you around 30 or less inches. Keep in mind this is only for 700 cfm. At 10 psi on a 355 cid engine, 80 % VE, 5000 RPM this is roughly where you are. You can play with this calc. to see for sure. Remember VE which goes down after torque peak and is most always less than 100 at peak. I used 80, but that is just a guess. Point is that unless your cooler is flowing through the 29x4 area, it is way small even with proper tuning.

Chris

[BLOWN64]

Originally posted by TurboS10
One of the probems with using a carb and boost is that it cannot react to air temperature. It sounds to me like when you are without the cooler, your carb is about right. When you add the cooler, you are getting a cooler, denser air charge which will need to be tuned for. Usually a cough or stumble is a lean condition, which would make sense for what you are telling use here.

I would also add that that cooler is really way to small. It is not to say it will not work, but you will be trying to overcome the pressure drop of the cooler along with the air velocity being so high throught the cooler it is not going to work properly. You have to realize that a pressure rating is not jack crap on a cooler. It should definately hold pressure, but cfm is what really counts. The tubes of an intercooler are stuffed full of fins that restrict flow to cause "intimate contact" with the cooler walls to increase cooling capacity. Most coolers on an engine of that size would be at least double that size for air-air. I am curious what the flow area is on the cooler. If it is flowing through the 12x4 inch area, which I suspect, you are choking it badly. If you read Corky Bell has a chart in his book Maximum boost to address cooler sizing. He shows a need for about 40 sqaure inches for 700 cfm. Your cooler if using the above config. is at 48 in. total before subtracting out all the area between the tubes which is probably about 40 percent. This puts you around 30 or less inches. Keep in mind this is only for 700 cfm. At 10 psi on a 355 cid engine, 80 % VE, 5000 RPM this is roughly where you are. You can play with this calc. to see for sure. Remember VE which goes down after torque peak and is most always less than 100 at peak. I used 80, but that is just a guess. Point is that unless your cooler is flowing through the 29x4 area, it is way small even with proper tuning.

Chris

The inter cooler is actually 29" long 6 1/2" tall and 4" thick. do you think it is still to small and should I try to change the secondary pump shot.

[TurboS10]

Well, that is even smaller than mentioned earlier. What is important is how the flow is through the cooler. Does air flow through the 6x4 section or through the 29x4 section? Easy way to tell is tank location and size. Are the tanks are 29 inches long or 6 inches long? If it is the normal I have seen on ebay, it is flowing through the 6x4 section with a little tank on each end. These are meant for small 1-3 liter import applications. If it has the big tanks, you should be okay.

Chris

[BLOWN64]

Originally posted by TurboS10
Well, that is even smaller than mentioned earlier. What is important is how the flow is through the cooler. Does air flow through the 6x4 section or through the 29x4 section? Easy way to tell is tank location and size. Are the tanks are 29 inches long or 6 inches long? If it is the normal I have seen on ebay, it is flowing through the 6x4 section with a little tank on each end. These are meant for small 1-3 liter import applications. If it has the big tanks, you should be okay.

Chris

the core is 18" long 6 1/2" tall and 4" thick. then with 5 1/2" long tanks

[TurboS10]

Yep, you definately have a severly undersized intercooler. I would be willing to bet you are making 10 psi or more on the compressor side of that cooler and it is only getting 5 to the engine. You really need 2 or 3 times that size for a V8. There is a rule of thumb for intercoolers to keep in mind: It can not be to big! Another option would be water/air cooler if you are limited by size. If it was me, I would put that sucker back on ebay and get some of your money back. It will never work properly.

Chris

[BLOWN64]

Originally posted by TurboS10
Yep, you definately have a severly undersized intercooler. I would be willing to bet you are making 10 psi or more on the compressor side of that cooler and it is only getting 5 to the engine. You really need 2 or 3 times that size for a V8. There is a rule of thumb for intercoolers to keep in mind: It can not be to big! Another option would be water/air cooler if you are limited by size. If it was me, I would put that sucker back on ebay and get some of your money back. It will never work properly.

Chris

You think this is what is making it stumble, buck remember its fine until I floor it.

[87442lover]

Originally posted by BLOWN64
Iam running the prochargerwith 10 lbs of boost on a 355 cid with a holley 650 double pumper. when I floor the throttle its like its hesitating but only when the carb is at full throttle if i let up just a little it runs fine Iam thinking it is the pump shot but then again procharger told me it was the ignition so i got an msd 6al and it didnt help.

Starting to buck at high RPM? Did you check for proper fuel/air mixture? cold dense air will throw off your mixture and make it run lean. This is only a guess I'm throwing out there. Do you have an O2 sensor? You could check it that way real easily with a volt meter.

Could also be running rich becuase of the obstruction in the airflow. Just a thought.