cast vs tubular manifolds
02-05-2009, 09:02 AM
#22
I just posted this in another thread, but it is applicable here as well:
I have heard about Stainless Steel exhaust systems cracking, but I have also heard about cast manifolds cracking. Also, many of the cheap stainless steel exhaust manifolds use medium grade stainless steel.
I spoke with Speed Force Racing yesterday, and they have their exhaust manifolds/headers available in 321 Stainless Steel. 321 will withstand very high temperatures, something like 2000 degrees. Also, you can ceramic coat the inside of them to help them run cooler. So I would not expect to see any problems with them. I am not sure what grade stainless steel sound performance racing is running, but it would be worth a call into them.
Using a header style exhaust manifold will lower your exhaust back pressure (Speed Force Racing indicates it is a significant reduction), which provides a number of advantages:
1. Less back pressure means your engine will breath better. The velocity of your exhaust gases will be higher, which will increase the scavanging effect that helps to draw in your intake charge. You should also be able to run a little more overlap between the intake valve opening and exhaust valve closing, which will help even more. This would be an ideal setup for some of the JWT cams. E.g., my C2 cams have 26 degrees of overlap.
2. Less back pressure should help the turbos spool up faster.
3. The turbos sit lower, so they are easier to get to if you ever need to perform maintenence on them.
You will probably need to run and external oil pump since you will not be able to rely on gravity to move the oil through the turbos. That's an added expense, but I think it would improve oil flow, which is good. You also will probably need an oil sump. Again, another added expense, but from my perspective, the more oil in the system the better.
I have been looking into this as I want to design a custom turbo system. But right now that is on hold until my Greddy kit sells.
If anybody wants a Greddy kit with a bunch of upgrades (ceramic coating inside and out on exhaust manifolds and turbo housings, turbo blankets, 750 cc injectors) for a very good price, PM me, because I really would like to get started on my custom setup! In other words, I'm a motivated seller.
I have heard about Stainless Steel exhaust systems cracking, but I have also heard about cast manifolds cracking. Also, many of the cheap stainless steel exhaust manifolds use medium grade stainless steel.
I spoke with Speed Force Racing yesterday, and they have their exhaust manifolds/headers available in 321 Stainless Steel. 321 will withstand very high temperatures, something like 2000 degrees. Also, you can ceramic coat the inside of them to help them run cooler. So I would not expect to see any problems with them. I am not sure what grade stainless steel sound performance racing is running, but it would be worth a call into them.
Using a header style exhaust manifold will lower your exhaust back pressure (Speed Force Racing indicates it is a significant reduction), which provides a number of advantages:
1. Less back pressure means your engine will breath better. The velocity of your exhaust gases will be higher, which will increase the scavanging effect that helps to draw in your intake charge. You should also be able to run a little more overlap between the intake valve opening and exhaust valve closing, which will help even more. This would be an ideal setup for some of the JWT cams. E.g., my C2 cams have 26 degrees of overlap.
2. Less back pressure should help the turbos spool up faster.
3. The turbos sit lower, so they are easier to get to if you ever need to perform maintenence on them.
You will probably need to run and external oil pump since you will not be able to rely on gravity to move the oil through the turbos. That's an added expense, but I think it would improve oil flow, which is good. You also will probably need an oil sump. Again, another added expense, but from my perspective, the more oil in the system the better.
I have been looking into this as I want to design a custom turbo system. But right now that is on hold until my Greddy kit sells.
If anybody wants a Greddy kit with a bunch of upgrades (ceramic coating inside and out on exhaust manifolds and turbo housings, turbo blankets, 750 cc injectors) for a very good price, PM me, because I really would like to get started on my custom setup! In other words, I'm a motivated seller.
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