Quote:
Originally Posted by DarkSunrise
The odd thing is, it appears based on a few independent dynos that "the other" catted UEL header seems to eliminate the torque dip completely. Wonder what the secret behind their design is.
|
Different runner length & collector style. There is a lot involved with how scavenging affects work. The car I tuned this week made something like 10-15% WHP gain at peak from just the header. FT86speed factory posted a dyno of theirs making less than 10% iirc. I dyno tuned before and after the header install (no other changes)and if anything the tune was more conservative with the header...
The engine load in the torque dip was fairly low so I am going to guess the scavenging was not so efficient in the torque dip with the catted header. Mind you this was a prototype... I was pretty disappointed at first until we pulled up the finished results and i was actually surprised at the fact it made a fairly consistent torque increase at nearly every RPM and it really didn't fall off much up top. I think if I would have played with the VVT a tad more up top i might be able to hold and extend the power to a higher RPM than I usually tune for. possibly usable power upwards of 7,800-8,000RPM even on pump gas. However I obviously don't recommend revving to 8,000 as it hasn't been thoroughly tested in extreme conditions.