Do any of you know if it is possible to cut some of the material off the collector to make the 2.25" opening into a 2.5" opening, and thus fit into a 2.5" downtube? The only thing I can think of that wouldn't make this work is that there wouldn't be enough curve left in the collector's sides to make a tight seal with the downtubes.
Making Header Collectors Larger
- Thread starter pablon2
- Start date
Mike8675309
Registered User
Stock opening is 1-7/8". I know Tbird88 ports them open to 2". I feel that more than that would be tough to seal. I also come to understand there is an issue with going above 2" too deep into the port.
If you search on the phrase port and user Tbird88 you'll see pictures of the outlets.
Ported 2" to 2.25" down tubes is going to pretty much be the limit until you start looking at going to some headers that are setup differently.
If you search on the phrase port and user Tbird88 you'll see pictures of the outlets.
Ported 2" to 2.25" down tubes is going to pretty much be the limit until you start looking at going to some headers that are setup differently.
Well if I'm not mistaken pablon2 has a set of Kooks mid lenght headers. Should that be the case then no you really do not have enough material there to just grind them out. None of the collectors that Summit sells would work in this instance because those collectors are more or less for full lenght headers and are usualy under the car(so there much longer in lenght) rather than in the run pointing downward to the downpipes. The only thing you could do in this instance is to fabricate custom collectors, remove the old ones and weld the new ones inplace. I dont think Summit has any 3-1 collectors which is what is needed for V6 headers, all of them I see are 4-1 collectors which could be used on V8's or inline 4 cylinder engines.
Could I ask why you are determined to use 2.5" collectors? You do understand that 2.5" collectors and downtubes will kill off some of your lowend punch and power dont you?
Could I ask why you are determined to use 2.5" collectors? You do understand that 2.5" collectors and downtubes will kill off some of your lowend punch and power dont you?
Collectors
What I saw that Summit sells is
A Ball type flange that is able to welded onto The end of a header collector
Thsi turns the old 3 bolt type header gasket into a ball flange
What I thought of doing is Grind the Opening to 2 1/2 inches or larger which would basically remove the flange But But the new Flange and weld it onto the end of the manifold I belive these come in 2 1/2 and 3 inch size
What I saw that Summit sells is
A Ball type flange that is able to welded onto The end of a header collector
Thsi turns the old 3 bolt type header gasket into a ball flange
What I thought of doing is Grind the Opening to 2 1/2 inches or larger which would basically remove the flange But But the new Flange and weld it onto the end of the manifold I belive these come in 2 1/2 and 3 inch size
To answer the question...why the 2.5" headers/downtubes...I had planned to do the SCP 2.5/3/2.5 exhaust system with headers and 2.5 " downtubes. The headers SCP sells have 2.5" openings, not 2.25" so I figured I needed the larger opening especially to mate to 2.5" downtubes. I currently have a 2.25/2.5/2.25 flowmaster system. Bill E told me that would be a restriction with the HP I plan on generating (300+ rwhp) so then began my search for headers/downtubes. Would I lose power if I mated the 2.25" collectors to my current Flowmaster system? It'd be cheaper and easier to just do this, but I don't wanna lose hp or a HG seal. Also, regarding low end torque, how much would I lose? I'm forcing a bit more air into the engine than b4 so I can afford to have it flow easier on the way out (less back pressure), thus hopefully not hurting the low end torque. At least this was my thinking.
I really wish I knew what to do at this point to get the best performing system. Any ideas are greatly appreciated. Thanks!!
I really wish I knew what to do at this point to get the best performing system. Any ideas are greatly appreciated. Thanks!!
MIKE 38sc said:
Well 2.5" collectors and downtubes slow down the exhaust gas velocity which kills low end torque. How much? Well I cant exactly say because I have no idea what else you've done to the motor, nor what you actualy expect from it.
What RPM range would you like your powerband to in?
Just to be honest with you the mid lenght Kooks headers are dismal performers. There primary tube diameters and lenght are set more closely to an engine with a usable powerband of 4000-9000 RPM and thats where they would work best. 2.5" collectors on primaries of that size would go pretty much hand in hand with that range as well.
Here's a general rull of thumb when looking for headers.
The larger the primary tubes are the higher in RPM range they move the powerband.
The shorter the Primary tubes are the higher in RPM the powerband moves to.
Do you see a trend here?
I've never seen a street driven car that needed primary tubes shorter than 36". Tubes of this lenght will make good usable power in the 800-5500 RPM range provided that they are not too large in diameter. The ideal diameter for this range is 1 5/8" however 1 3/4" that are at least 36" long will shift power from the 800-5500 range to 1500-6300 range.
What RPM range would you like your powerband to in?
Just to be honest with you the mid lenght Kooks headers are dismal performers. There primary tube diameters and lenght are set more closely to an engine with a usable powerband of 4000-9000 RPM and thats where they would work best. 2.5" collectors on primaries of that size would go pretty much hand in hand with that range as well.
Here's a general rull of thumb when looking for headers.
The larger the primary tubes are the higher in RPM range they move the powerband.
The shorter the Primary tubes are the higher in RPM the powerband moves to.
Do you see a trend here?
I've never seen a street driven car that needed primary tubes shorter than 36". Tubes of this lenght will make good usable power in the 800-5500 RPM range provided that they are not too large in diameter. The ideal diameter for this range is 1 5/8" however 1 3/4" that are at least 36" long will shift power from the 800-5500 range to 1500-6300 range.
85mm throttlebody eh? whew thats a MONSTER! Hope you got enough cam(much bigger than a mild cam which is bigger than stock) and set of good flowing heads, sounds like your engine is mostly stock however.
Should that be the case I hate to break it to you but you're not gonna get any benefit from that huge throttle body, infact it may hurt things even worse.
Sounds like you would be better off with a 70mm or 75mm throttlebody at the most. Use a set of full lenght headers for best results on a street engine.
Here's a chart I found showing the various tube diameters there flow area and the HP levels they support. This should be helpfull to you in designing your exhaust. Just remember to be honest with yourself about what your use of the engine(street or race) and match your tube diameters to meet your goals. Now when I said the use of your engine I mean just that. Just because you may take your street driven car to the track occasionaly that does not mean you want a race setup, because the engines performance will suffer badly if you stray too far towards a race setup and be a pig on the street.
Should that be the case I hate to break it to you but you're not gonna get any benefit from that huge throttle body, infact it may hurt things even worse.
Sounds like you would be better off with a 70mm or 75mm throttlebody at the most. Use a set of full lenght headers for best results on a street engine.
Here's a chart I found showing the various tube diameters there flow area and the HP levels they support. This should be helpfull to you in designing your exhaust. Just remember to be honest with yourself about what your use of the engine(street or race) and match your tube diameters to meet your goals. Now when I said the use of your engine I mean just that. Just because you may take your street driven car to the track occasionaly that does not mean you want a race setup, because the engines performance will suffer badly if you stray too far towards a race setup and be a pig on the street.
Attachments
The 85mm TB is b/c I don't wanna have to buy another one if/when I have engine work done. At worst I figured it'd be overkill for the time being as I know others with it and it doesn't kill performance on a stock block. What I am wondering is if I'd be okay hooking my current 2.25/2.5/2.25 flowmaster system up to the midlength headers I have. I don't wanna restrict HP nor risk blowing a HG. Seems like I get a different answer from nearly everyone that responds. But, looking at the chart you included I should be okay with the current setup. I have to think though that the chart doesn't factor in the HG issue with our engines and therefore we MAY wish to error on the side of caution and pick a pipe slightly larger in diameter, again, this discussion opens another can of worms. I don't think full length headers are an option b/c I need to have carbs and I "heard" that they leave no room for a resonator when installed with cats. I could remove the resonator but then I've "heard" that the sound is compromised. I'm getting a headache now. 
MIKE 38sc said:
pablon2 one of the biggest perpetuated myths about the SC is that the exhaust causes the HG's to blow. This is simply NOT TRUE!
The HG's blow because Ford only put 4 small diameter headbolts per cylinder on this engine and skimped on the heads deck thickness.
The most common reason for HG failure on engines that are not modified to the hilt and running over17 psi or so of boost is electrolysis. Electrolysis eats away at the gasket material from the water jacket openings until it reach's the fire ring of the gasket. Once it gets to the firering it only takes one good romp off boot and poof, blown HG!
I do not know who told you that you had to run carbs to use full lenght headers but I'll say it right here in public that there an idiot and do not know what there talking about. You should stop listening to them as there doing you a disservice.
Now back to your qeustion about your Flowmaster exhaust.
Hook it up! you will be just fine! Truth is it will probably meet your needs much better than what you were contemplating doing in the first place.
The HG's blow because Ford only put 4 small diameter headbolts per cylinder on this engine and skimped on the heads deck thickness.
The most common reason for HG failure on engines that are not modified to the hilt and running over17 psi or so of boost is electrolysis. Electrolysis eats away at the gasket material from the water jacket openings until it reach's the fire ring of the gasket. Once it gets to the firering it only takes one good romp off boot and poof, blown HG!
I do not know who told you that you had to run carbs to use full lenght headers but I'll say it right here in public that there an idiot and do not know what there talking about. You should stop listening to them as there doing you a disservice.
Now back to your qeustion about your Flowmaster exhaust.
Hook it up! you will be just fine! Truth is it will probably meet your needs much better than what you were contemplating doing in the first place.
XxSlowpokexX
Registered User
Yes..
Head gaskets in our cars blow for a multitude opf reasons...Electrolysis and lack of good head sealing are the two major ones....
That with a bad tuneup and detonation..WHAMMO Instant failure.
ARP headbolts and stock gaskets usually hold up good.
One thing peopel fail to realize is you are dealing with an old car.....with boost..That probably never had a good tuneup done..You have no idea how many SC;'s Ive seen with different plugs or some that had never been changed at all.
An 85mmTB.....I have one..Never used it..Looks nice on my shelf.
Persoannly exhaust wise Id perfer 2.5/3/2.5 or 2.5 all teh way back dual although not needed.. And flowmasters dont flow very well...
However on your car they should be just fine.
Teh Kooks midlenghts have a soft crappy collector area..One thing I would hav edone if I kept mine was weld on an 2.5 inch steel exhaust donut to teh flange and cut out excess material..They you would hav ea leak free 2.5 inch opening which is what it shoudl be....The factory Kooks headers squeeze the collector size down to 2.25 from what looks like 2.5 inch..And it always leaks after awhile..Otherwise the headers are nice..
Anyway how does true three inch duals with a resonator and cats sound:O)
Head gaskets in our cars blow for a multitude opf reasons...Electrolysis and lack of good head sealing are the two major ones....
That with a bad tuneup and detonation..WHAMMO Instant failure.
ARP headbolts and stock gaskets usually hold up good.
One thing peopel fail to realize is you are dealing with an old car.....with boost..That probably never had a good tuneup done..You have no idea how many SC;'s Ive seen with different plugs or some that had never been changed at all.
An 85mmTB.....I have one..Never used it..Looks nice on my shelf.
Persoannly exhaust wise Id perfer 2.5/3/2.5 or 2.5 all teh way back dual although not needed.. And flowmasters dont flow very well...
However on your car they should be just fine.
Teh Kooks midlenghts have a soft crappy collector area..One thing I would hav edone if I kept mine was weld on an 2.5 inch steel exhaust donut to teh flange and cut out excess material..They you would hav ea leak free 2.5 inch opening which is what it shoudl be....The factory Kooks headers squeeze the collector size down to 2.25 from what looks like 2.5 inch..And it always leaks after awhile..Otherwise the headers are nice..
Anyway how does true three inch duals with a resonator and cats sound:O)
David Neibert
SCCoA Admin
Mike,
I think he meant to write cats instead of carbs. It used to happen to me all the time when I was on that damn Atkins diet.
Pablon,
I've got the same SCP exhaust system you first mentioned consisting of Kooks headers, with 2.5 downtubes, hi flow cats, Magnaflow resonator with dual 2.5" inlet and single 3" outlet, 3" center pipe, then it splits back to dual 2.5" pipes and into a pair of Dynomax mufflers.
It works fine. The exhaust system was my very first mod and while it didn't feel like it added much if any power, I didn't feel like it made less power either.
If your headers are only 2.25" they will still be okay and the 2.5 downtubes will probably still attach to that crappy ball and socket connection on the headers. If not just have the exhaust shop make a couple short adaptors.
BTW, Mike is correct about not needing larger than a 75mm TB unless your going for the better looks of the MP 85mm.
David
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I meant to say cats, not carbs. I was actually trying to work when I wrote this. Damn work can be so distracting sometimes. Anyhow, the SCP website doesn't recommend full length headers when using cats b/c it is a tight fit. That's all I was getting at. I'd rather not layout the money to get another exhaust system when mine has only 800 miles on it so....I think I'll put the 2.5" downtubes on the headers I have (Kooks emailed me today and said the 2.5" downtubes will fit) and then have an adaptor between the ends of the 2.5" downtubes and the 2.25" cats. SOUND LIKE A PLAN??? I assume this should work and will be cheaper too. I don't claim to know this stuff inside and out like some people do, just looking for some helpful information and if along the way I can save some time and money and not trash the SC in the process, then all the better. This is the first time I have actively tried to improve my SC in the 9 years I have owned it. Thanks for the input.
Anyhow, the SCP website doesn't recommend full length headers when using cats b/c it is a tight fit. That's all I was getting at. I'd rather not layout the money to get another exhaust system when mine has only 800 miles on it so....I think I'll put the 2.5" downtubes on the headers I have (Kooks emailed me today and said the 2.5" downtubes will fit) and then have an adaptor between the ends of the 2.5" downtubes and the 2.25" cats. SOUND LIKE A PLAN??? I assume this should work and will be cheaper too. I don't claim to know this stuff inside and out like some people do, just looking for some helpful information and if along the way I can save some time and money and not trash the SC in the process, then all the better. This is the first time I have actively tried to improve my SC in the 9 years I have owned it. Thanks for the input. MIKE 38sc said:
XxSlowpokexX
Registered User
Paul,
Seriously try to find teh steel 2.5 inch exhaust donuts..Old trucks and bigblock car sused to use them
They can be welded onto your collectors and will solve many of your problems.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7947513660&category=33634
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7948421200&category=6763
Just make sure they are 2.5 inch..Get the idea??
Seriously try to find teh steel 2.5 inch exhaust donuts..Old trucks and bigblock car sused to use them
They can be welded onto your collectors and will solve many of your problems.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7947513660&category=33634
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7948421200&category=6763
Just make sure they are 2.5 inch..Get the idea??
pablon2 said:I meant to say cats, not carbs. I was actually trying to work when I wrote this. Damn work can be so distracting sometimes.
LOL!!!!! Sorry I came across so gruff on the carb remark. That comment about needing carbs to use full lenght headers sounded like someone that use to hang around here and he was notorious about shoveling the BS.
I kinda get upset when people hand out some off the wall advice such as that to someone thats obviously only looking for help and possably they do not know that there being fed a line. Playing with cars costs enough money as it is by doing things right, and nothing is more discouraging than to spend your hard earned money on what you've been told is the greatest thing since sliced bread only to learn you would have gotten just as much satisfaction by setting that pile of money on fire.
Like David and Damon have said what you have now will be a good start for you and later on when you're ready to start doing some more things you can always make some changes.
From your first posts I got the impression that you were trying to build some killer setup and was basicly starting from scratch.
Go ahead and put your headers on and bolt up that exhaust and then enjoy your car for awhile.
Since you indicated that you intend to do some more tinkering on down the road, take some time and hang around here for awhile, use the search feature for topics that you're interested in and enjoy them. Once you come up with things you cannot find answers to come on and post your qeustions, theres several good guy's here that have real good running SC's that would be more than happy to help you in anyway they can. I see 2 of them have already responded to you, and I'm not talking about myself either!
Mine dont run yet!
But it used to........long story so I wont go into it now. LOL!!!!I'm gonna pull a fathead here but, I weld this donut to the collector ball and then weld the downtube to the other end of the donut? Why wouldn't I just mount the downtube to the collector ball? Or were you meaning to use this in place of the collector ball and thus would give me a true 2.5" ID measurement?
Paul
Paul
DamonSlowpokeBaumann said: