I've been reading over on the 3.0 FI forum and it seems that the whipple upgrade doesn't care for the jba's. However, I believe that possibly changes if you get a bamatune. I don't recall that being confirmed though. So the issue comes up here as to whether the 4.0 will benefit from headers once you are blown. I guess what I'm wondering is if anyone has bothered to be the guinea pig for this? My 4.0 is an '02 so I'm not certain just how different it is from the 98-00's/'01's.

From all my discussions from jba (i've been considering the headers for a while now despite not yet being blown), they don't seem too high on the headers for basic street driving. This is not to say you won't benefit, but from what I was able to get from them, the headers to be best if you do a fair amoung of towing. I didn't get the feeling that for running around there would be too much improvement and from what I've been told/read the stock manifolds actually flow very well.

So are there any opinions on this? Anyone tried them? I've also read that the ceramic coated headers are a bigger benefit over the chrome due to getting rid of more heat and not releasing it into the bay. Don't know how accurate this is but can't hurt to get more info on this perspective as well.

Not much help, but I put them on my 4.0 and it was night and day sound and performance. That was with the blower and I think if I would have had the truck tuned with the headers and exhaust I would have put it into the high 260's or low 270's at the wheels.
Jesse

Thanks Orion. It's a starting point. Short of actually trying it we'll never know. I've already done full exhaust short of the headers and since the headers are a decent investment, picking other peoples brains helps with the decision. Unless someone else has done it, I know brian was talking about adding the headers, maybe I'll be the guinea pig and do a before and after dyno.

Even if you're not blown some more input on the headers would be nice.

Centrifugal and Roots type blowers build boost differently. What works well for a centrifugal, like Orions, doesn't always work well for a roots type blower.

I have the headers and will be doing a before and after dyno for the M90 in my plans. Maybe over the next month or so.

Centrifugal and Roots type blowers build boost differently. What works well for a centrifugal, like Orions, doesn't always work well for a roots type blower.

I have heard about this as well. For example, a lot of guys who mod their Ford Lightnings found that with the roots type blower, airflow mods made in front of the blower (i.e., larger intake tube, larger TB, MAF, Filter) made more HP gains for their money than things like heads or headers. Those mods in front of the blower plus upping the boost with a different pulley gave them bigger gains....and were also cheaper.

I am also using an m90. I'll be very interested in the dyno results. I spoke to JBA again, and despite what has been discussed on other boards their dyno results show a 7-8% (hp and torque) increase with use of the headers and exhaust on a 2004 ranger SOHC. In speaking with tech support he indicated that the power was increased throughout the rpm range (which is also shown in the dyno results (http://www.jbaheaders.com/images/dyno/04rangerdyno.jpg)). I guess my main point in bringing this up is the fact that header benefits on the sohc still seem to be elusive. I only know of two SOHC's with the headers, one guy I don't know at all and won't take his word for anything until I meet him, thought he does like them. The other got a pre-production EE s/c which was nothing but trouble. He wasn't/isn't really a car guy so I'm not really sure how accurate his assesment would be.

Enough rambling, with any luck at the end of some of our testing we'll have some more definitive answers regarding headers with or without a blower.

I have heard about this as well. For example, a lot of guys who mod their Ford Lightnings found that with the roots type blower, airflow mods made in front of the blower (i.e., larger intake tube, larger TB, MAF, Filter) made more HP gains for their money than things like heads or headers. Those mods in front of the blower plus upping the boost with a different pulley gave them bigger gains....and were also cheaper.

The L's already have a pretty decent exhaust designed for that particular application so headers on a stock block don't really do much for them. When anything is done to increase the breathing (cams, porting, etc), then the long tube headers do help considerably. When bigger pulleys are added, the boost does go up, but adding headers then does drop the boost down a bit - shows that the headers do help breathing efficiency.

The 4.0 SOHC does breathe pretty well as it is and the stock exh. manifolds are pretty good on the flow bench. I've ported some exhaust ports and checked the flow with and without the manifolds and really didn't see much difference (disclaimer: your results may vary......lol). For a n/a engine, I'd stay with the manifolds, but every engine that I've seen boost added to has benefitted from headers - the more exhaust you can get out of the cylinder, the more air/fuel you can get into it.

Bird

The L's already have a pretty decent exhaust designed for that particular application so headers on a stock block don't really do much for them. When anything is done to increase the breathing (cams, porting, etc), then the long tube headers do help considerably. When bigger pulleys are added, the boost does go up, but adding headers then does drop the boost down a bit - shows that the headers do help breathing efficiency.

Good point Bird. I guess comparing the L motor and the 4.0 is definitely like comparing apples and oranges in this case. Still, since you're a L owner, you might find this page interesting.

http://www.timskelton.com/lightning/race_prep/powertrain/dyno_data.htm

Good point Bird. I guess comparing the L motor and the 4.0 is definitely like comparing apples and oranges in this case. Still, since you're a L owner, you might find this page interesting.

http://www.timskelton.com/lightning/race_prep/powertrain/dyno_data.htm


Yep, already been there......................

I have been for my base dyno. I actually went to two places since the first guy seemed to be having problems and came up with a horsepower rating of 132. :rolleyes: I think the guy just stole a hundred bucks from me.
The second place I went the guy had no problems and over three pulls we got a consistent 174 horsepower and 210 torque. This was on a dynojet.
With the torque program from Doug I hit the 210 right away and then slowly dropped off over the rest of the rpm range. Not to bad for a 4x4. My sig has all my mods. Now to finish my gauge pod and get the M90 on.

I have the JBA headers on my truck and they definately gained on the dyno.

--Sean

i have a pair of borla headers on my 94 4.0. i know that its not a 98+ or a sohc motor, but i also have a vortech blower on it too.

i installed the blower and ran it for a while with the stock exhaust manifold/system and it ran descently, but i installed a set of borla headers after the blower was installed for a bit and i noticed a slight difference with the way the truck ran. altho i havent really driven the truck in over a year now, i still start it up and run it weekly, but i havent had a chance to take it to the track and see what kind of times i get with the blower/header setup compared to just the blower/stock exhaust setup.

but from a "feels like" point of view i felt like the headers helped out the setup. (im sure if i would do more engine work to it then the benefits of the current setup would be even greater)

but adding headers then does drop the boost down a bit

This subject is very interesting to me. In any case helping an engine breathe better should improve power. So, who here has headers that are designed to scavenge exhaust? I think all the JBA's are designed to scavenge. I'm a little rusty but I'm pretty sure that exhaust scavenging means that the headers flow so that they will actually suck out the exhaust on the exhaust stroke. There was a debate about this (a couple of years ago on the 2.3T forums) about how scavenging headers are bad for turbo aplications. If this is the case, then boost could actually be going straight out the exhaust. Also, since most supercharger aplications come with tuners, the engine's ignition timing and fuel timing are tunned for this extra air in the combustion chamber. But if the extra air is not there, I would think a lean condition would also be experinced. Could retarding the cam timing fix this? I think it may if indeed boost is going right out the exhaust.

Found this at popularhotroding.com/enginemasters under exhaust science.

Assuming for a moment no flow losses, the piston traveling down the bore will pull in one-eighth of 350 cubic inches. That's 43.75 cubic-inch, or in metric, 717cc. If the compression ratio is say 11:1, the total combustion chamber volume above this 717cc will be 71.7cc. If a negative pressure wave sucks out the residual exhaust gases remaining in the combustion chamber at TDC, then the cylinder, when the piston reached BDC, will contain not just 717 cc but 717 + 71.7 cc = 788.7 cc. The result is that this engine now runs like a 385 cubic-inch motor instead of a 350. That scavenging process is, in effect, a fifth cycle contributing to total output.

So it appears that exhaust scavenging actually does suck air out of the combustion chamber. So what do you guys think about it??? I know there are some guys here that are about to go to the dyno with a supercharger on. If anyone can provide before and after dyno results this could greatly help figure out if there is a large power loss (rather a relatively small power gain). Let me know what ya'll think :thumbsup:

I will post a follow up when I get my M90 on.

groovy :popcorn:

I picked up 14 peak HP and 14 peak TQ from my headers and exhaust. It smoothed out my HP curve and gave me a little more torque up high too.

Outstanding! Were those the JBA headers???

I've been watching this thread for a long time now - waiting for someone to actually come along with real facts and reasons - MV has shown the facts - here's the reasons.

I've been building engines of all kinds before a lot of the guys here on RPS were even born and I've NEVER seen headers hurt power in a 'properly set up system'. On any engine, you want as much of the exhaust as possible out of the cylinder before the intake charge starts coming in there - otherwise, you have a diluted charge that will make less power. Where you get into problems on a forced induction engine is a cam with too much overlap that allows some of the incoming charge to go right out the exhaust valve before it closes. Fortunately, we don't have cams for either the OHV and the SOHC that have that much overlap - even the 422 is a fairly mild cam in comparison to offerings for other engines. Headers and porting/polishing will very much ENHANCE power output with forced induction street engine as long as a decent cam with mild overlap and high lift is used (hmmmm, sounds just like the cams we have in our 4.0's).

I will say that if you're running a cam with a lot of overlap but have a restrictive exhaust keeping the exhaust velocity down to where the intake charge isn't being pulled out, then opening up the exhaust with headers and/or free flowing exhaust will drop power, but that's the fault of the cam. Some engine builders/tuners will actually shoot for the biggest cam they can with a lot of overlap, jetting appropriately to guarantee the most cylinder filling even though they're still wasting fuel out the exhaust, but those aren't street vehicles running at 14.7:1 a/f ratio controlled by a computer.

Bird

Yep they are indeed JBA's....here are my last 2 dyno sessions. The only difference between the two sessions is that in the first graph I have stock exhaust manifolds and exhaust/mufflers and the second is my recent one with the headers, 3" exhaust, and a flowmaster with 3" inlet dual 2 1/2 outlet. In both cases we did two pulls, one with the FMU connected and one without it. The FMU caused me to run WAY rich and killed a lot of power.

http://www.explorerforum.com/data/500/16158dyno_2b.jpg

http://www.explorerforum.com/data/500/16158dyno_3.jpg