Here is a back to back of my old H/C/I 302 vs my 347. Both engines have the exact same heads and same intake manifold exept with the 347 it was ported and same exhaust set up . This side by side was made up couresy of the Magic man Grady! Thanks again.
5 spd, you are the only person I have ever heard that gained nothing from long tubes. The gain from long tubes wil l be in low end to mid range though. It will not show up in track e.t.'s. Are you saying you got no seat of pants or torque gain? Grady's dyno chart show significant low-mid grunt improvement and at least 10 rwtq over most non-long tube dynos that I have seen. This equates to much better street driveability and enjoyment. I have learned that peak HP and TQ and track times have nothing to do with fun and driveability around town. I never go to the track so that is where my goals are now.
For example, I want more low end tq so when I hit the gas in any gear, it goes. Not just upper RPMS. I hate redlining my car anyway and would definitely not be a candidate for a 7000rpm stang.
If you look around you will see similar results. Some on the corral have posted this as well as other sites.
I think there are cases where gains will be seen, no doubt. Unfortunately in most cases the hp/per dollar isn't to good, especially with some of the cons it has by having longtubes.
I do like the sound better though, but I think many get fooled by it and think they gained something significant...and some actually gain something. On a h/c/i car, any quality 1 5/8 inch header will do, shortie or longtube in my opinion.
The 1 5/8 inch opening is bigger than your exhaust valve on the head which is even restricted more with the actual valve and sealing lip on the head. So the headers will flow plenty...
I think this is the first time I've ever agreed 100 percent with you!
The common 302 based 6000 rpm windsor does not move enough air to reap the benefits of long tubes. A 10 rwtrq gain in 320 rwtrq car is about 3 percent... you're not gonna feel that! And is it worth shelling out the loot for new headers and mid pipe? I don't think so.
If you want to feel "low end grunt" then build the motor for horse power then gear it up appropriately. You'll feel it plenty then.
Adam
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