I am debating weither or not to put headers on my 85 tpi trans am. I dont wanna have to buy a new y pipe, since mine is pretty huge already, i just wanna get rid of the ol' cast iron manifolds.
My concern is this : my stock manifolds have AIR, and i know my engine is set to run WITH the air system in place, and if it is removed it leans out my engine because it gets reading that it thinks is wrong without the AIR (and no, im not gunna retune my PROM to adjust this, because its an 85 and i dont have a programer. If anyone knows a guy who will tune 85's let me know...)
Will shorty headers help or hurt my engine performance?

 

I would do it. You won't get the gain that you would get from the long tube headers, but I put a set on my '91, and I noticed slightly better MPG, and it also made my 305 sound a heck of a lot better than it did with the stock manifolds. They're not terrible to put on, but I'll give you a piece of advise take the passenger side engine mount loose and jack the engine up, and it will make getting the passenger side header in much easier.

 

MPG's and sound, 2 things i dont really care about. (13.5 mpg cause of the lead foot, keep it quiet to stay low key to the police) I just wanna know if its gunna help or hurt my performance, im in it for the POWER!

 

Then you might consider headers and their accompanying Y-pipe. Though you may think your OE Y is big, in comparison to after market set-ups, it's not. Another consideration: If you purchase headers without the Y, you may spend more having one fabbed than the piece is worth in time, expense and performance.

JamesC

 

let's be even more clear

you aren't going to find headers which bolt right up to the stock y pipe

the newest 3rd gen is 20 years old. if there hasn't been demand for headers to stock y pipe when more 3rd gens were on the road then chances are nobody will create a set as demand decreases

 

BTW, Removing AIR system has zero effect on the program of the computer. Shorties with the corresponding y-pipe are a worth while investment. If you wish to keep the smog there are headers available with air tubes on them.

 

My engine computer is set to run with fresh air being pumped into the manifolds, when the 02 sensors give the computer the readings, my computer compinsates for the fresh oxygen being pumped in. When you remove your AIR on a TPI, your o2 sensors read ur exhaust without any fresh air, tells ur computer which thinks AIR is still hooked up, and it leans your fuel. All of the guys in DIY PROM have taught me this because of the discussions on how to program that out. BUT i have an 85, and it really isnt tunable without switching to an 86 ecm and harness, which i do not want to do because its a pain in the *** and expensive.

------- I just want to know if putting summit shorty headers (100 bucks) on my trans am will help or hurt the performance. ------------

Because they flow better, but then again it will make my engine run lean without tuning my prom.

 

PLEASE PLEASE PLEASE

research when AIR functions in comparison to what is "closed loop"

then, research when O2 sensors are active be that in closed or open loop


good luck

 

 

Yeah the AIR stuff will not affect you're engine's performance at all. The headers on my '91 do not have the air ports on the and the smog pump has been deleted as well, and there was not any performance issues after I did this. The O2 sensor reads what is coming to it and adjusts accordingly. If you want performance either get the complete kit with the new Y-Pipe, or go all out and put long tube headers on. Long tubes usually give you the best results.

 

okay, thanks for the answers everyone! definitely helped with my decision on the headers.

 

All the guys in DIY PROM were wrong. I have done alot of research into this as I have also deleted my AIR system.

When the ECM commands the AIR diverter solenoid ON, it offsets the minimum O2 voltage required to set a check engine light but does not offset the actual reading of the O2 itself.

You can tune an 85, it just takes patience and a long, empty road.