Long duration cams with a tight LSA (long overlap period) and stock exh manifolds do not mix. The reason is the that the overlap period allows for the exiting exhaust gasses to draw more a/f into the cylinder but this doesn't happen when the engines have the stock manifolds. The longtubes allow for scavenging while the stock manifolds (and shortys) do not.I know there are a lot of different contributing factors (different dynos, more aggressive tuning etc), but I cant imagine that headers will really make a 20hp+ increase on a T-bird. If that were true, I may say goodbye ported manifolds and get some kooks!
I'll make this quick as not to contribute to any hijacking of the thread. 42s would be enough for a stock 4v on e85. A single 340lph pump or two 255s will work.While we are on the subject of injectors would 42's or 60's be too much for my 4v? I want to experiment with E85 so I will be needing more injector, I think my dual 255 walbro's are up to the task and I'll be fabricating new filter to fuel rail lines and in tank lines / y-fitting.
THANK YOU! That's what I've been trying to cram into the skull of certain boneheaded people but nooooo, they won't hear of it!Long tubes are the best option for heavy, autmatic transmissioned cars as they produce more midrange hp/tq than manifolds, shortys and mid lengths. Mid lengths would be the next best option and IMO stock manifolds and shorty headers are not a viable option in any way
I've had many set of 4V and 2v headers but have never seen those for this body.The answer is:
You can get the KOOKS with 2.5" collectors or the bigger 3" collectors.
Some here have made their own by modifying other headers to fit the MN12.
I have killer software program that provides the header dia/length for any given combo and i've never seen it recommend a primry length shorter than 30".THANK YOU! That's what I've been trying to cram into the skull of certain boneheaded people but nooooo, they won't hear of it!
Thanks for the valuable input Nick. Headers are on my list of things to buy now that I better understand how cam profiles and scavenging complement one another, but I'm doubting they'll happen for at least 12-18 months. For the time being I'm focusing on cleaning up the rough edges in the tune and for the heck of it I'm putting a P&P'd plenum on it to go with the TB to see if it makes any noticeable difference in airflow.IMHO - it needs a good set of headers. Stock MN12 manifolds start off 0.25" smaller inside than Mustang ones and the bends are horrendous. Cheap crappy Mustang long tubes are worth 18-20RWHP over Mustang manifolds so you can estimate about a 20-25RWHP gain from just a header swap in this chassis.
Then the auto sucks about 5-10RWHP over a stick, electric water pump is another 5-10, elbow/TB/inlet pipe is another 5-10. It all adds up but its a lot of small expensive stuff here and there. The 300ftlbs shows the potential, usually the HP limit is about 10 less than the torque peak with that intake on similar combos when maxed out.
The tighter LSA will make the torque peak higher, but will kill the power after the HP peak faster all else being equal. Retarding the cams with those exhaust manifolds will probably just cost power everywhere.