Thumpy turbo cam?
A cam I really like for 5.3's for best overall power, fastest spool and a 6000-6200 shift point is 217/225 114lsa.
The biggest cam I like to use in a turbo 5.3 in an application such as this is a 223/223 114lsa. Both cams have 3-5 degrees of advance ground in.
Both cams will be noticeable in terms of idle sound, but they won't sound like N/A cams that are 230+ duration and ground on tighter center lines.
When you have exhaust pressure that is 1.5-2.0 times higher than intake pressure the motor cannot scavenge effectively. When the motor cannot use the exhaust/exhaust port to scavenge effectively, adding overlap is not going to benefit power production. It will negatively impact it. While it may sound cool at idle, that's about the only cool thing it will accomplish versus a smaller cam like I have suggested.
I will try and get to your email soon for a more in depth and personal conversation.
Hope this helps.
The biggest cam I like to use in a turbo 5.3 in an application such as this is a 223/223 114lsa. Both cams have 3-5 degrees of advance ground in.
Both cams will be noticeable in terms of idle sound, but they won't sound like N/A cams that are 230+ duration and ground on tighter center lines.
When you have exhaust pressure that is 1.5-2.0 times higher than intake pressure the motor cannot scavenge effectively. When the motor cannot use the exhaust/exhaust port to scavenge effectively, adding overlap is not going to benefit power production. It will negatively impact it. While it may sound cool at idle, that's about the only cool thing it will accomplish versus a smaller cam like I have suggested.
I will try and get to your email soon for a more in depth and personal conversation.
Hope this helps.
Thank you Martin. I've been doing some PM'ing with a few others and it seems that the smaller cams are just going to perform so much better.
I look forward to your email when you get the chance.
I look forward to your email when you get the chance.
Not to hijack this thread, but people mentioned that the thumpiness of a cam can also comes from tuning. What are some things you can modify in the tune to make a car have a choppy idle?
when i first got my car it had a cam and a choppy idle that sounded good, now after i have tuned it the idle is smooth.... makes me miss it. tried a few things but haven't gotten the idle back to how it was.
when i first got my car it had a cam and a choppy idle that sounded good, now after i have tuned it the idle is smooth.... makes me miss it. tried a few things but haven't gotten the idle back to how it was.
Not to hijack this thread, but people mentioned that the thumpiness of a cam can also comes from tuning. What are some things you can modify in the tune to make a car have a choppy idle?
when i first got my car it had a cam and a choppy idle that sounded good, now after i have tuned it the idle is smooth.... makes me miss it. tried a few things but haven't gotten the idle back to how it was.
when i first got my car it had a cam and a choppy idle that sounded good, now after i have tuned it the idle is smooth.... makes me miss it. tried a few things but haven't gotten the idle back to how it was.
Not to hijack this thread, but people mentioned that the thumpiness of a cam can also comes from tuning. What are some things you can modify in the tune to make a car have a choppy idle?
when i first got my car it had a cam and a choppy idle that sounded good, now after i have tuned it the idle is smooth.... makes me miss it. tried a few things but haven't gotten the idle back to how it was.
when i first got my car it had a cam and a choppy idle that sounded good, now after i have tuned it the idle is smooth.... makes me miss it. tried a few things but haven't gotten the idle back to how it was.
I meant to post this for you so you can see how this cam will idle if you want sound. To me this sounds pretty badass can't get much choppier than this. 
Last edited by Camaro9969; Feb 19, 2014 at 07:12 PM.
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My buddies car with a TU2 in it. 402 with an LS3 top end, GT88 turbo. Probably switching to a Tick cam here soon.
2000 SS Turbo Camaro - YouTube
2000 SS Turbo Camaro - YouTube
Thanks man!!! 
I had a tu2 like I said before made it idle like that drove awesome on the street and performed well at the track. You can have that idle just tell your tuner.
I had a tu2 like I said before made it idle like that drove awesome on the street and performed well at the track. You can have that idle just tell your tuner.
I can't seem to find your email, can you direct me to it or give me your address?
Martin,
I have a 98 Firebird Formula I will be putting a L33 (5.3) in and adding a either a S475 or a PT7675 to. I will be using my current TSP stage 2.5 5.3L heads, and FAST 92mm intake. The car is an M6, and I'll be going with either 3.42 or 3.23 gears in it. Its mostly a street car but gets taken to the track maybe a half dozen times a year.
I would love a cam that is very aggressive sounding with a lot of chop. But I realize this is not usually a good combo for a turbo car (I don't want it too laggy down low). I have heard a CTS-V with a 78mm turbo on a 238/242 .609/.612 113+4 cam and it sounded AMAZING, but I can't help but feel it may not be the best performer, and overall performance is more important than sound. Please point me in the right direction.
Here's what the email said;
Martin,
I have a 98 Firebird Formula I will be putting a L33 (5.3) in and adding a either a S475 or a PT7675 to. I will be using my current TSP stage 2.5 5.3L heads, and FAST 92mm intake. The car is an M6, and I'll be going with either 3.42 or 3.23 gears in it. Its mostly a street car but gets taken to the track maybe a half dozen times a year.
I would love a cam that is very aggressive sounding with a lot of chop. But I realize this is not usually a good combo for a turbo car (I don't want it too laggy down low). I have heard a CTS-V with a 78mm turbo on a 238/242 .609/.612 113+4 cam and it sounded AMAZING, but I can't help but feel it may not be the best performer, and overall performance is more important than sound. Please point me in the right direction.
Martin,
I have a 98 Firebird Formula I will be putting a L33 (5.3) in and adding a either a S475 or a PT7675 to. I will be using my current TSP stage 2.5 5.3L heads, and FAST 92mm intake. The car is an M6, and I'll be going with either 3.42 or 3.23 gears in it. Its mostly a street car but gets taken to the track maybe a half dozen times a year.
I would love a cam that is very aggressive sounding with a lot of chop. But I realize this is not usually a good combo for a turbo car (I don't want it too laggy down low). I have heard a CTS-V with a 78mm turbo on a 238/242 .609/.612 113+4 cam and it sounded AMAZING, but I can't help but feel it may not be the best performer, and overall performance is more important than sound. Please point me in the right direction.
The smaller the turbine wheel the more exhaust pressure will be present at higher rpm and load. Scavenging and utilizing exhaust pulses whether reflective or positive are very important to clearing spent exhaust gas from the cylinder. If timed right they can even help pull intake charge into the cylinder.
Where we open the exhaust valve and where we close it will affect this the most as will where the intake valve opens.
Because of all this in s turbo motor it's even more paramount to match the cam to the back pressure the set up will produce, at least for me that's how I do it.
So I've found smaller cams with more lift can help extend the Power curve and make more power.
Not for every application but for most street cars with turbo engines this is true.
Yeah, in lesser detail, I have heard the same that the S475 will allow for greater overlap, and thus, greater potential to run a thumpier cam in the car successfully.
Ideally I would like to run the S475 because of this and it's price. However, it's sheer size over the PT7675 may not allow me to, as I want to run AC in the car, and don't like the idea of reducing the S475's massive 5" outlet into a 3" downpipe (and I don't really want to hack up my front bumper either to let the exhaust run out like many do).
So, I'm trying to find a workable solution to fitting and using the S475, but if I can't find a solution I like, I may end up going with the PT7675.
Any recommendations you can give me for each cam and the otherwise same setup would be much appreciated.
Ideally I would like to run the S475 because of this and it's price. However, it's sheer size over the PT7675 may not allow me to, as I want to run AC in the car, and don't like the idea of reducing the S475's massive 5" outlet into a 3" downpipe (and I don't really want to hack up my front bumper either to let the exhaust run out like many do).
So, I'm trying to find a workable solution to fitting and using the S475, but if I can't find a solution I like, I may end up going with the PT7675.
Any recommendations you can give me for each cam and the otherwise same setup would be much appreciated.