This is on my 89GXLN/A Runs are pretty much side by side. First run is with bonez race pipe to single cat-back
The top run ( that I filled in) is base with headers that I converted speed to RPM. It was 154.4 rwp without s-afc tuning and timing advance. The middle run or red line is 148 rwp that was the second header pre-silencer run that we messed up on...

Misconception

1). You will lose low end?? I gained low end with headers compared to streight pipe stock manifold.
2).You wont gain much if any withuot a street port especialy??? I gained 8 rwp up to 12 rwp on the 2 runs with heade pre-silencer combo. Most people said it wouldnt be much of a difference. I didnt feel much a difference but thats because it gave me that extra power so smoothly and evenly not just top end..One person said I might actually lose power if I wasnt running a street port.
3). You lose torque??? Torque was greatly increased by 9 or 10 ft lbs.

After my base header run 154.4 rwp I decided to put the afc to -12 across the board. To my surprise I gained an even 4 rwp throu out the entire band but the sensors werent picking up the signal so we stoped at 6k rpm but if you connect all the dots on the graph it makes a streight even 4rwp gain up to 6k were we stoped. If this continued we would have seen 158 rwp or more. Stock port stock ecu. Not bad at all.

The reason I think I saw so much gain with heads is because I have fully ported manifolds to engine block and custom short ram intake with forced cool air hose on a 9 inch filter.

 

Yes, their are to many preconceived notions, In regards to having a Header. My RB Header, straight pipe, presilencer with S.S Bruleen Exhaust System Is smoking!!! I didn't feel any loss of torque, If any.

 

Hmmmm... I guess it's time to get rid of my straight pipe and get a header then. My straight pipe has no cats at all though, so I wonder how much difference that would make? Now if I only had a couple hundred bucks lying around........

 

That's good information. I've always believed headers would make the most power.

The only issue I may have a problem with when I get headers is noise. Some people say they're loud as hell, some people say it's louder, but not that bad. While we're kind of on the subject, what are your thoughts, von?

 

if your concerned about noise plain and simple don't get headers, mind you von has fully ported manifolds, and a street port, man that's gotta sound so nice!, WhAAAAAAAAAAAAAAAAAAAAAA

 

If you are worried about noise, Summit Racing sell a baffle or I don't know what they call it. You tack weld it in the collector of the header. It is to reduce the noise and they claim no power or torque loss. They are only about $30 or so. I have considered it myself on my headers.

 

SR,
I thought you were toting a TII. You mean downpipe then right?

 

Im running a RB single out header (i found it in the j yard attached to a motor i pulled for 120 bucks ) Anyways, it resonates like a MOTHER ****** from about 4500-6500. Anyone know how to ditch this honda sounding deal? I have straight pipes with a rice shop muffler and some sort of pre silencer, someone told me if i ditched the presilencer it'll get rid of it, is that true? thanks

 

STREET PORT??? I have no street port what so ever. I do have ported manifolds to engine block...

Rattan??? Dood thats what a streight pipe exaust is. Its no cats. Thats what I have and thats what I compared it to. Bonez race pipe to single cat back streight through comprende?

Noise??? haha. If someone wants to come down and listen to it go hit me up. Its just as quiet as the streight pipe. Just make sure theirs no exaust leaks. I think it also depends on your muffler. Brand names are for show like apexi bomex exc. I have a cheap 100 doller 16 inch billit muffler. Seems to quiet everything down better than the others.

ITS NOT TO LOUD> HONDAS WITH GUTTED CATS AND CAT BACK ARE LOUDER.

Thats mosconception number 4 now that I think of it. from 0-4k its as quiet as the race pipe. After that its buzzy and pretty loud but not loud enoughf to get pulled over unless you were gunning it next to a cop. Seriously. I was worried about sound to but after I put them on idle , cruze and 0-4k is quiet. Ask anymore ? you like.

 

When I put headers on my '88 I noticed a very definite increase in power. Enough so that I was impressed. After that setup I dualled it out and gained low end but lost top end compared to the collected header.

 

Von,
Are these results with the aux port actuation? If so, stock sleeves or pineapple ones?

 

LOL, that's pretty much what I was looking for. I know it's going to be louder when you're on the gas, I was curious about idle, cruise, and half throttle up to about 4k RPM.

 

Sorry, I'm a moron. I read single cat-back as a single cat-convertor. . OK, I'm all better now.

 

Oh that explains it.

JerryLH3: Yeah definatly dont worry about cruze , idle and 0-4k.

RXseven: I dont have a fully functioning 6th port, however I do have the pineapple sleeves BUT thier cut , shaved and J/B welded inside the engine block ((( dont try this unless you know what your doing))) I did this to eliminate the rods and Sleeve rods that actually hurt low end. My mod I believe gained me HP. Compare my low end ( 0-3800rpm) to a stock 7 if you have to. I could be wrong though. Torque is evident with the headers. It seems a little easier to take off from a stop than the streight pipe. That graph does show more power and torque at 2k...

NOtice how smooth the power curve is. This is probly because I got rid of the obstructions in the intake manifolds like the 6h port rods.. My VDI is wired open so im sure my torque will rise drastically when I put my airpump back on. Im dynoing it again within a couple of weeks with better clutch , light steel flywheel, ported TB , VDI closed - open, and S-AFC tuned. and timing advance. It will be interesting to see if I hit 160rwp without street port. Thats a 35 rwp gain over stock. Well see.

 

when i had it on my car before you got it someone told me if i got the rb presilencer that noise would go away..take off that 'silencer' and put that rb presilencer on there that should do it

 

Hmm piece of junk just give it to me charles

 

Ill think about it. LoL, man, i dont even know why im worried about a ******* exhaust noise when i dont even have a ******* motor, ****, ill never have a motor. Maybe ill go up to Nates house and gank his motor, ****. Thanks guys

 

You answered your own question.

 

Um, no i didnt, i did not know that a rice muffler, that like everyone runs, would cause just my car to resonate. And it seems that it was the presilencer bc its the same one that "Presetlimits" ran and he said he had the same problem. He has "nice mufflers"

 

von, I think we have the same setup except mine does not have a ported manifold but I got mine dynoed at 153.1 without S-AFC tuning too. And the same as you, the computer did not pick up my RPM. Oh yeah, 6-ports wasn't working either

 

Well your ports were obviously open then to make about the same hp. The only difference is I dont have the rods that your has otherwise their both open.

Dont worry after tuning i will be making lots of HP. Your S4 should not gain as much with the S-AFC as mine because it already leans out a good amount. Are you going to dyno it soon?

About the RPMs I have many RPM runs but decided not to show those ones because their was no overlay to compare them to. ALso I dont have an IGnition box but plan on new coils and MSD 6a. But yeah your making good power.

 

Von, what pipe size are you running into the single, 2.5" in/out or 2.25"? Do you have the part# to that Billet muffler, I might consider it since it nice and quiet.

 

Umm its all 2.5 inches. Should be Inside diameter.

Yeah the custom cat-back only costed 250 even including everything and the muffler. They dont do mandrel bends for that price but its still a nice job... I got the billit at express hitch and muffler but im sure they sell them in other shops as well.