Well I got it done. Finally after about a week and a half or more with a JBA header sitting in my bedroom I finally got it installed. I came home from work, pulled into the garage and opened the hood and let it cool off a bit and went to work.
It was surprisingly easy. I was going to replace all the bolts with APR bolts and use a copper gasket, but I couldnt get either one in time and I wasnt wainting any longer.
The only real problem I ran into was the header flange bolts on the top row for the #1 and #4 cylinders. The tubing for the stock header is smaller and I was able to easily get to these bolts. However, after installing the JBA header, with its larger tubes those bolts were a big pain to get tightened down. I was finally able to the #1 cylinder bolt torqued to spec, along with all the others but the #4 cylinder bolt I had to do by hand cause it just wasnt happening with a torque wrench and a socket so I had to use a wrench and just get it as close to spec as I could.
After I got everything back together I took the Focus up to around the Kansas border where they have a lot of hardly driven, nice roads that have plenty of straight run and a few twisties. I have to say, Im impressed. Putting the thing on there I kept getting this bit of skepticism that it was going to be all that. However, after a few launches, high speed runs and just general driving, I have to say I like it a lot.
What I like a lot is the low end. Noticeable low end punch, though I would love to put it on a dyno and see just how much. Maybe some more track time is in order? Normally if I put it in first and then punch it, I have a very noticeable, very annoying drop out that costs me plenty off the line. But with the JBA header that is nearly all gone. I get a much better launch to say the least instead of having to feather the throttle some so it can catch up with itself.
I notice much better mid to high end pull too. Usually around 5000 RPM I can notice it aint making much more power and usually just shift it out to the next gear. Now it seems to pull on through that which is really good. It also doesnt seem to bog down nearly as much when I shift, which Im gunna have fun with that.
Driving it with it in drive rather than manually shifting it still pulled well and recovered very well when the tranny shifted. Im going to take a HUGE ding in gas mileage on this tank I had so much fun.
All in all, I like it VERY much. I can hardly wait to get the rest of the exhaust done and then get started on some cam gears and stage 1 cams. After that Im going to have to finish the tranny project and go from there.
Ive heard some say you can pick up some mileage from going to a bigger diameter exhaust. It will be interesting to see if I get anything at all with the header. It will be on the next fill up though before I can see it cause I burnt some gas tonight playin'.
____________________ My car is a synner! It uses Amsoil Synthetic Lubricants.
2001 Pontiac Grand Prix GTP
It whines a lot, but I like it
Make sure you re-torque those bolts every couple of days for next week or two. It will help that gasket seat properly and is more likely to prevent leaks.
Thank you manninej, someone had told me that was a problem with the header bolts so I will be checking it. I used a new gasket at the header and at the collector just to be safe. I expected the bolts on the header flange to be all rusted and what have ya but there were actually all in really good shape. I would liked to have had the ARP bolts with the black oxide and some locking fastners but as good of shape the existing bolts were in I dont think it will be necessary.
____________________ My car is a synner! It uses Amsoil Synthetic Lubricants.
2001 Pontiac Grand Prix GTP
It whines a lot, but I like it
I noticed something new today. It seems the car performs better now when its warmed up fully now. It used to be that when it was cool that I got better acceleration and such and then when it was fully warmed up that slightly tapered off. Now, it seems like the Focus performs as it did before I installed the header when it is cold, then when the motor gets fully warmed up, it seems it accelerates and pulls better.
Anyone have or had a similar experience with JBA headers or other aftermarket header set up?
____________________ My car is a synner! It uses Amsoil Synthetic Lubricants.
2001 Pontiac Grand Prix GTP
It whines a lot, but I like it
leave your exhaust diameter the same. 2.25 is ideal for up to about 160hp. if you go too large you get a drop in delta pressure. basically, the air is stalling out in the tube and not exiting fast enough. its not building back pressure but its slowing the exit of the exhuast from the header. A muffler shop will tell you that you need "some" backpressure. they are wrong. they have the right idea but the wrong term.
I plan on getting a 2.25" cat back and flex pipe before long hopefully. My goal was to do all of the exhaust including the Cat., but Im not so sure Im going to mess with the cat right now, Ive heard some mixed reports of using a hi-flo cat and may just wait until the thing goes bad if it ever should.
TXFO, what are some of the ill effects of the delta pressure being wrong. In my analytical mind, everything about back pressure seems all wrong to me. I mean, I would think the idea is to get rid of the exhaust as fast as you can, so any constriction or such would slow that. Does not the cylinders have enough built up pressure to force the exhaust out on its own? Just asking cause thats an area I dont understand a lot of. The term 'backpressure' to me would indicate you have a force acting upon the release of the exhaust gases keeping them from completely flowing out which seems opposite of what you want.
Now, on the same hand it would seem that if you have the exhaust going from a small diameter tube, such as a header, into a larger tube or area such as the Cat or exhaust pipe you would set up a vacuum that would actually aid in pulling the exhaust gases out. Is this not correct then?
Just trying to educate myself on the process.
____________________ My car is a synner! It uses Amsoil Synthetic Lubricants.
2001 Pontiac Grand Prix GTP
It whines a lot, but I like it
ok. all backpressure is bad. you will hear all kinds of different things but the fact is there is no good amount of backpressure. backpressure is the flow of a medium against the current. watch the water in a tube shoot, there is always water flowing back up at the sides of the flume. same thing happens in the exhaust pipe and what this is doing is slowing down the delta. that is slowing the velocity of the exhaust. when you have a pipe that is too big, what you are doing is slowing the velocity by allowing the exhaust gasses to "pool". freeventing exhaust like having no header, dosent work because you need to create a current. now you need to create an efficient current. that is where size comes in to play. if you go too big, the gasses kind of stall in the pipe and while not creating backpressure because of the expanded volume, it lowers the overall efficiency of the system and is detrimental to the engine performance.
Yamaha has been making exhaust "throttlebodies" that open and close to maximize the efficiency of the pipes and keep the gases moving as quickly as possible.
going from small to large creates an eddy current at the junction and can create backpressure as well as air stall. maybe not extremely noticable in a light hp car but there IS a difference in performance.
Thank you TXFO for that very informative lesson there. I think I got it now. Great lesson. So is there anyway, other than just trying a series of different sized exhausts, to determine what the 'ideal' size of exhaust is?
I realize that modifications and such would probably change that, but taking say just a baseline motor, how would one go about determining that there exhaust is 'tuned' to their particular set up if possible?
Thanks again TXFO, very informative.
____________________ My car is a synner! It uses Amsoil Synthetic Lubricants.
2001 Pontiac Grand Prix GTP
It whines a lot, but I like it
our stock is 1 7/8" The best aftermarket choice for mild-medium modified engines is 2 1/4" beyond that the 2.5" is good for more aggresively tuned NA and low boost FI applications, for high boost FI 3" is optimal.
lol, silly rabbit... why do you think the aftermarket kits start at 2.25"? Trust me I've seen it happen, I know someone who is running an ebay turbo kit with the stock exhaust. Ok, so he isn't the brightest bulb on the tree, but he swears up and down that his exhaust is 2.25". Has he been talking to you?
i want to install a shorty header, can you use the factory cat with the 2.25 full exhaust (im new to ford, all this is diffrent from dodge) anyoneshelp would be greatly appreciated.thanks.
