Paxton with little boost???
- Thread starter Jsparks
- Start date
ILLSMOQ
Enthusiast
how would it give an indication of belt slippage? The belt does not squeal or make any type of noise when it slips....in fact the only way you can actually know that it is slipping is if you are data logging boost through the rpm range..split second box lets you do this. Even if you have a boost gauge, it would be hard to detect the typical belt slippage you get with the standard paxton setup...unless it was slipping really bad.
...........spraying it with belt dressing would make it slip even more
Hmm... something is wrong for sure. however, as others have pointed out, you need a concrete double check to get pointed in the right direction. Obviously, first, double check with some other type of boost gauge that there really is a problem, using a different tap-in point to elinimate the possibility of a vacuum leak issue on the Split-Sec, fittings, or anything associated.
After that, belt slippage would be the most common and easiest issue to check. Look for a polished belt, "VORTECH" lettering being burned off in a hurry, missing ribs, belt dust/shreds, bad tensioner/loose belt, etc. Something may be installed incorrectly, cant hurt to double check. Measure the pulleys, it is not impossible that something was built incorrectly.
If the belt checks out and slippage is not apparent, dig a little deeper. The next most likely causes would be some type of restriction/leak, either upsteam or downstream of the blower. Check everything, the intercooler would be especially suspect. If it has a damaged/plugged core inside, it could certainly cause this. The next suspect would be the Blow Off Valve- stuck open or connected/adjusted incorrecty?
After all the outer causes are ruled out, you have to look at the internal issues. Loose blower compressor wheel? damaged blower drive? Hub slipping on crank? Missing key on the blower pulley? There has to be a reason, and it is likely a very simple one.
After that, belt slippage would be the most common and easiest issue to check. Look for a polished belt, "VORTECH" lettering being burned off in a hurry, missing ribs, belt dust/shreds, bad tensioner/loose belt, etc. Something may be installed incorrectly, cant hurt to double check. Measure the pulleys, it is not impossible that something was built incorrectly.
If the belt checks out and slippage is not apparent, dig a little deeper. The next most likely causes would be some type of restriction/leak, either upsteam or downstream of the blower. Check everything, the intercooler would be especially suspect. If it has a damaged/plugged core inside, it could certainly cause this. The next suspect would be the Blow Off Valve- stuck open or connected/adjusted incorrecty?
After all the outer causes are ruled out, you have to look at the internal issues. Loose blower compressor wheel? damaged blower drive? Hub slipping on crank? Missing key on the blower pulley? There has to be a reason, and it is likely a very simple one.
Thanks VSpeciatly......I will email this to my tuner and see what he comes up with.
Just a thought,
Let's say you install the 12lb pulley and cap the rpm's at around 5,500. This would give you more boost through-out the entire curve and not let it get to high to hurt the motor.
Just a thought,
Let's say you install the 12lb pulley and cap the rpm's at around 5,500. This would give you more boost through-out the entire curve and not let it get to high to hurt the motor.
Why dont you just work to getting your car right. If its right and working as it should be, you will have more then enough boost and power thoughout the entire rpm range. These cars are a handfull stock and even more so, when you have 650+ at the wheels. Just get it working correctly and dont waste any money buying extra parts.
Was just a thought Mike....I do intend to fix the problem
some feedback from my tuner..
Hi Josh.
I will check. I can put an optical tachometer on the blower pulley and directly measure belt slip. It is a little more difficult to measure crank pulley slip, but I can investigate it if I don’t see any belt slip. This should tell me a lot.
I check all of the vacuum lines and fittings and everything looks ok. I even te into the power brake booster line to get a better signal and the reading was the same. The pressure transducer that I use in the shop is laboratory grade instrument and is calibrat and verifi. It is ok.
If I can’t find anything then I will start to dig further. I can log inlet pressure and temperature to the blower and blower outlet temperature. This will give me the blower efficiency. With that data I can plot the points on the performance chart and see if everything looks reasonable. This will also be a good measurement of any inlet pressure drop issues.
I fairly certain it is just belt slip on top end. Check out the data. This is not the final tune and the fuel is slightly rich. You can see the boost is falling off a bit on top end.
I attach a cobra file. One plot has a centrifugal blower and the other a roots blower. The tests are from 2 different Cobras, but you can see the torque shape from the higher boost at lower RPM. This is why I suggest to crank up the boost and limit the RPM. You will gain a pile of torque at the RPM in the mid range without a bunch of stress on the engine.
Again, our altitude is 1200ft. The boost will be lower than the cars at sea level.
Thanks for all of the input. I will see if I can get is straiten out.
Maybe it will stop snowing soon…..
Hi Josh.
I will check. I can put an optical tachometer on the blower pulley and directly measure belt slip. It is a little more difficult to measure crank pulley slip, but I can investigate it if I don’t see any belt slip. This should tell me a lot.
I check all of the vacuum lines and fittings and everything looks ok. I even te into the power brake booster line to get a better signal and the reading was the same. The pressure transducer that I use in the shop is laboratory grade instrument and is calibrat and verifi. It is ok.
If I can’t find anything then I will start to dig further. I can log inlet pressure and temperature to the blower and blower outlet temperature. This will give me the blower efficiency. With that data I can plot the points on the performance chart and see if everything looks reasonable. This will also be a good measurement of any inlet pressure drop issues.
I fairly certain it is just belt slip on top end. Check out the data. This is not the final tune and the fuel is slightly rich. You can see the boost is falling off a bit on top end.
I attach a cobra file. One plot has a centrifugal blower and the other a roots blower. The tests are from 2 different Cobras, but you can see the torque shape from the higher boost at lower RPM. This is why I suggest to crank up the boost and limit the RPM. You will gain a pile of torque at the RPM in the mid range without a bunch of stress on the engine.
Again, our altitude is 1200ft. The boost will be lower than the cars at sea level.
Thanks for all of the input. I will see if I can get is straiten out.
Maybe it will stop snowing soon…..
