Thread: Flow numbers Stainless PLOG and ported front exhaust manifold

Of course they flow well. They're bigger. Still cheap chinese crap that rusts in 3 days.

SD rust now.. That's news to me!

Originally Posted by usetaboost

How is what I am doing any different than comparing two different heads? If those of you that think I'm doing it wrong maybe YOU should spend your time and money doing this and share the results. All these tests are for is for manifold flow numbers and if a ported manifold is worth doing in terms of flow. I'm not hardcore into these cars. If this was for my grand national I probably wouldn't even bother getting flow numbers. I'd get dyno or track numbers. If it's only a 5hp gain in the end, so be it. I'll open my toolbox before I open my wallet.

And what's it matter if I use a head? Every single person on here thinks the downpipe and the front manifold is the major cork and what do all you guys think you have to do? Buy headers. All I ever read on this forum is that headers are the first mod that should ever be done because GM deliberately built these cars to explode if you put a cold air intake on them.

Settle down man. I'm just trying to help bring some relevance to your test.

Look at an exhaust port on a head. It's in the shape of a D. Which roughly matches the port on a stock exhaust manifold. The powerlog is a circle, and by it diameter alone, it will easily outflow the stock manifold. Or a ported manifold. If you don't use a head, you are completely removing the portion of exhaust that initiates the speed, direction, and other flow characteristics while the exhaust gasses are in their most expanded state. Your test would be valid if you were deciding which to use for an underground sprinkler distribution manifold, but it means very little on an operating motor.

Also, I hate headers. From all the cars I've had, they've been huge headaches for the little gain (if any) they offer. I never recommend then anymore unless you are trying to run faster than 12's. The last car I built, the 04 in my sig, made 320whp all day long through stock manifolds, E85, 3.4 pulley, and a very conservative tune. It could have easily made more, but the fuel pump couldn't keep up.

Yeah I was thinking about that port design when I found out that the head has a D port. If I end up getting more timing at wot that will tell if the ported manifold really has any effect. I'm not a fan of headers and I think the plogs are built just as poorly. I'm probably not going to get a chance to make another run with a scan tool hooked up til next week. Hopefully I can get it on a day where at least the temp is close to where it was when I made the first runs. Never know, a ported front manifold might actually end up making the knock retard worse.

Originally Posted by REDCOMPG

SD rust now.. That's news to me!

Mine are rusty under the car, good ole MN winters. Manifold parts still shine somewhat.

2 years on my sd's, no rust.....

Originally Posted by GTPpower

Settle down man. I'm just trying to help bring some relevance to your test.

Look at an exhaust port on a head. It's in the shape of a D. Which roughly matches the port on a stock exhaust manifold. The powerlog is a circle, and by it diameter alone, it will easily outflow the stock manifold. Or a ported manifold. If you don't use a head, you are completely removing the portion of exhaust that initiates the speed, direction, and other flow characteristics while the exhaust gasses are in their most expanded state. Your test would be valid if you were deciding which to use for an underground sprinkler distribution manifold, but it means very little on an operating motor.

Also, I hate headers. From all the cars I've had, they've been huge headaches for the little gain (if any) they offer. I never recommend then anymore unless you are trying to run faster than 12's. The last car I built, the 04 in my sig, made 320whp all day long through stock manifolds, E85, 3.4 pulley, and a very conservative tune. It could have easily made more, but the fuel pump couldn't keep up.

I was about to respond to this exactly what you said, but you made the point very well. Without bolting it to the head I think the numbers are useless. I'll go unbolt my gto headers and get those numbers too, that should correlate well to the 3800 engine. If I want more flow I'll go get some 4" PVC pipe, that should flow a lot more. I'm not trying to be mean but that seems to be the testing method. Even when flowing heads you put a pipe to simulate the cylinder or exhaust. It's not "which one flows more air" but which one will flow more air out if the head. GTPower was just trying to show you why doing it that way is a waste of time and why the results couldn't be used much less weren't even close to scientific.

does it really matter? The plog is bigger. It flows more obviously. Isn't that the point of putting on headers, to get more flow to reduce the knock retard? That's fine i can keep all the changes I make to the car and scan readings to myself. I have no problem with that. I'm not wasting my time as far as I'm concerned. If I did want to waste time and money I'd try to make this car fast.