Header bungs, how many?

I have a set of raw headers that I plan to have coated but first I must decide how many bungs I will want to add. As well as if I want to do a evac setup.

The engine will be strip / highway driven, 10:1 comp. I'm not sure if I should do the evac or just run breathers on the valve covers. I figure at least one afr bung on each collector but EGT is where I'm really unsure. How valuable is EGT on this type of engine that might possibly use nitrous at some point.

The o2 stuff is the most useful IMO.

I wouldn't waste the time with EGTs on your application

Crank case evac won't hurt and it's cheap power.

dfree383 wrote:The o2 stuff is the most useful IMO.

I wouldn't waste the time with EGTs on your application

Crank case evac won't hurt and it's cheap power.

evac don't work well mufflers if its street used IMO just run 4 breather with wrist bands... Or use a elec vac. pump just when racing

the evac does work ok with mufflers if you put the evac tube in behind the mufflers, I've done a couple like this with good results.

It's apples to oranges as my application is different......I put two O2 bungs and two egt bungs.  I have an O2 bung in a corner cylinder primary tube and the other one is in a middle cylinder.  The bungs are halfway between the head and collector.   I like them in the primary so they don't get contaminated by air from the collector due to low rpm or reversion.

I can swap the O2 sensor from corner to inside tube in just a minute.  Can check to make sure that the corners/inside or not too lean or rich vs the others.  

EGT bungs are the same way, corner and inside.  Just they are 2" from the head instead of middle of the tube length.

Thanks fellas,
My plan is to run a large diesel 4" straight flow muffler on each header and then a 3" pipe out the muffler (turn down most likely). Do you think I should just do a 4" or 5" out? I can get a large diesel muffler that is 4" in and 5" out for $65.00 each. I figure since most folks around here run 3" exhaust on small block and mod motor Mustang's I would be fine running 4" for a 533cu.

I was advised not to run a strong vacuum system on a street drive engine as it would harm the engine. I just want the engine to be sealed yet be able to breath.

David Cole wrote:It's apples to oranges as my application is different......I put two O2 bungs and two egt bungs.  I have an O2 bung in a corner cylinder primary tube and the other one is in a middle cylinder.  The bungs are halfway between the head and collector.   I like them in the primary so they don't get contaminated by air from the collector due to low rpm or reversion.

I can swap the O2 sensor from corner to inside tube in just a minute.  Can check to make sure that the corners/inside or not too lean or rich vs the others.  

EGT bungs are the same way, corner and inside.  Just they are 2" from the head instead of middle of the tube length.

Mr Cole. Those look like pretty short and unequal length headers.... Or do my eyes deceive me?

windsor wrote:

David Cole wrote:It's apples to oranges as my application is different......I put two O2 bungs and two egt bungs.  I have an O2 bung in a corner cylinder primary tube and the other one is in a middle cylinder.  The bungs are halfway between the head and collector.   I like them in the primary so they don't get contaminated by air from the collector due to low rpm or reversion.

I can swap the O2 sensor from corner to inside tube in just a minute.  Can check to make sure that the corners/inside or not too lean or rich vs the others.  

EGT bungs are the same way, corner and inside.  Just they are 2" from the head instead of middle of the tube length.

Mr Cole.  Those look like pretty short and unequal length headers.... Or do my eyes deceive me?

Yes they are short and unequal. Didn't have much of a choice. They are 2 3/8" with a 4.5" collector. Fenderwell type kinda sorta. If I would have put the collector under the car I would have only had about 1.25-1.50" ground clearance. No room to put put front fender exit headers due to fuel cell in corner at front. No room for rear fender exit without cutting half the A pillar away. On my Bird the A pillar is directly behind the fender behind the front wheel.

I might be leaving some on the table, but it seems to work ok. Last time out was a month ago. At 2960 lbs on motor it went 5.210@ 132 with a 1.120 60'. Best 60' ever and tied for best ET ever. Leave at 4400, shift at 7000.

very nice numbers, a 1.120 60' is crazy fast for a door car, how good is 60' on the jug?

David Cole wrote:

Yes they are short and unequal.  Didn't have much of a choice.  They are 2 3/8" with a 4.5" collector.  Fenderwell type kinda sorta.  If I would have put the collector under the car I would have only had about 1.25-1.50" ground clearance.  No room to put put front fender exit headers due to fuel cell in corner at front.  No room for rear fender exit without cutting half the A pillar away.  On my Bird the A pillar is directly behind the fender behind the front wheel.  

I might be leaving some on the table, but it seems to work ok.  Last time out was a month ago.  At 2960 lbs on motor it went 5.210@ 132 with a 1.120 60'.  Best 60' ever and tied for best ET ever.  Leave at 4400, shift at 7000.

Good info and they seem to work ok indeed... Thanks much.

butterbean wrote:very nice numbers, a 1.120 60' is crazy fast for a door car, how good is 60' on the jug?

I don't really know.  Converter is all wrong for the jug.  Way too loose at 6100 flash NA.  On spray had a slower 60', slower 1/8 ET, but more mph.  The last time I tried it was at the US43 Ford Thunder race.  It zinged the engine on a 200 shot plate so quick it hit the shift point and was in in high gear at .40 sec. (as per my data logger)  Made for a long ride in high.  But it ran about 137.  Haven't tried it since.  The converter I have works great for 5.30 heads up index, so I didn't want to mess with it.  

I had a very nice 10" FTI nitrous converter built for it but sold it to Ward (Dr's Wife Racing) before I ever installed it.