I want to put on some ported exhaust manifolds, but the heads I have arn't port matched. Will this be a issue for them to perform right? I could clear out the exhaust ports on the heads, but I only have a dremel, would this be ok you think?
thanks

You can just throw on the ported manifolds without doing anything to the heads and still see gains. The internal welds on the stock V6 manfolds are restrictive; removing these welds from the inside and welding the outside portion of the joint will bring you a small performance and economy gain. The performance in probably in the range of 1 to 3 hp but in overall "bang for the buck" the manfils are the cheapest hp to a stock V6 in my mind. You costs are generally about $40 to $50 or so ($20 for manifold gaskets, $20 for Rodney's exhaust stud kit [I didn't see these on his site now looking quickly--does anyone know if he still carries them?], and maybe $10 for a six pack of beer for a friend to weld the manifolds if you don't know how to weld) .

do you think a dremel would be adequate to open up the exhaust ports on the heads, its alot of material. So, if I match the exhaust manifold gasket to the heads, and open them up to that spec, I should be ok? I'm just double checking so I don't screw my heads over.

[This message has been edited by NickD3.4 (edited 03-05-2008).]

Um, i'm not sure you want to try porting the heads with a dremel while they are still connected to the block.

I ported the stock manifolds with a dremel, and hooked them up to the 3.4, they are like night and day.

there not on the block, they are off, and getting ready to go to the machine shop. I want to do the work before I send them off for the machining. When you say manifolds, are talking intake, or exhaust?

[This message has been edited by NickD3.4 (edited 03-05-2008).]

I've used both a dremel tool in the past and the die grinder the last few years. I eventually burned up the dremel on my second set of exhaust manifolds. Its not designed for that amount of work like a die grinder is. I'd get yourself a diegrinder. It goes a lot faster when porting the manifolds.

the manifolds I am having someone do, I only care about the exhaust ports on the heads them self at this point. If I match the exhaust manifold gasket to the head ports, and mark it. then grind it to match the gasket, am I ok doing this? or is there something I should know about before hand, so I dont jack up my heads.

The dremal can be used if you invest in a top quality cutter you use the old gasket if the gasket is in good enough shape(optimist )to mark the port the exhaust should be a bit smaller than the manifold port,, you have to guestimate where the gasket will "fall" where it will match both head and manifold.. the head port should be a bit smaller than the manifold port so none of the hot speeding gas flatens against the flange of the manifold,, a new or in great shape drill used with the dremel will be O K,, I also use round files course,a small bevel file is outstanding for this,,how far you go into the port is up to you.. the gain is in the exhaust manifold you must cut away the stainless steel that protrudes into the opening, this acts as a damn and causes the manifolds to glow,, the weld must be cut out to the pipe open the inlet remove all weld inside the pipe only a small amount is left at the entrance where pipe is welded to the flange there should be a bevel at the very entrance,the bevel will be sort of like the head valve seat,, some of the stainless that protrudes into the pipe at the joints is difficult to get to use a file get rid of it ..push a piece of cardboard(like a cerial box) into the pipe to prevent dammage to the walls, coiled up ,the cardboard will fit tight.. 1 inch into the pipe at the connection this stainless steel should be grinded smooth smoooooth for flow.. dyno testing has shown a good exhaust manifold port job to bring 5 h p!! together with a ported Y pipe 5 to 8 hp the manifold & Y pipe seem to compliment each other..Ive lost my files on this will look it up , think it was michigan fiero club about 2000
Dyno test showed ported pipe out performed some custom headers..
It take 2 hours per manifold port to do a good job unless you have full power air tools,or quality electric hi speed. 8 hours for the mid and end port,1 hour each for the front ports 10 hours to port,of course I am thourough and precise when I port
weld flange to pipes so as it is not noticible
I purchased a set of ported pipes but only the inner stainless had been done.. this is time consumming work, do not speed or hurry along the results of a good meticulous port job are more H.P, more efficient, engine cooler running.,better mpg I can not ost photos mayby some one will post what a completed port looks like ,, read my post on port match about 2 weeks ago can not remember the original post name
most people do not do a good job because of tedious work involved.listen to radio,stop and let tools cool use always better to alter Y pipe to fit manifold, rather than alter manifold to fit Y pipe a smooth no bind fit and there is less change of crack pipe
wd 40 good to cool bit ,and keep metal from binding to bit and port
fins inside port are to be left alone you can sharpen a small amount

Go to fiero focus .com/ this is northern ill. site there are interesting test here..check out the what works and what does not !! dyno test show an 8 hp increase from just porting
headers or exhaust porting is the single most beneficial change to a V 6

[This message has been edited by uhlanstan (edited 03-06-2008).]

thanks, I appreciate it!

Not true Nick.

Essentially the ported manifolds are required to let the heads breath. The ported heads are the next step and will give you more added power than the ported manifolds exponentially. Ported heads by themselves will be constipated with unported manifolds.

For hogging out the big bump in the exhaust port, it is handy to pick up a cross cut carbide burr at your local tool supply place. They are worth not alot and they work with an electric drill.

The dremel bits are better for the finer cut work. The dremel extension will get down into the manifold to do the job, but, it will take longer. This isn't bad if you are new to porting. It works slower with less chance of catastrophic error.

Good luck

Arn

Arns85GT is correct they compliment each other ,, what I am saying is the the exhaust manifolds are so choked, they are like a clogged artery in a body,, you only have to look at them ,,no expertise is required they are such a disaster,,,it is the manifolds on the V6 that keep the 2.8 from breathing enough to perform at hi rpm,,


The single best modification you can make to the 2.8 V6 is to open up the exhaust manifold this is more important than porting the intake manifold or the head.. I presently have 2 sets of exhaust manifolds I am porting. I said "crap" out loud the first time I eyeballed the manifolds ports I could not imagine a worse looking exhaust port untill I looked in the 2nd set,, The fiero head ports are like a raging river with the fins adding push compared to the damed up manifold..

Im money mad ,never had any, it makes me mad

It seems a electric drill would have enough power to cut out the ports, that works huh. I'll look into it. Is the "hump" in the exhaust ports you talk about way down in the heads?

If you are going to use the STOCK exaust logs do not port match the exaust. you MUST have a smaller hole in the heads than the pipes to reduce backflow. Because of the crappy log design you will get pressure pulses and having an exaust shockwave go back int othe heads are a bad thing. If you are going to throw away the exaust manfiolds and buy real ones (not sprint, but they are better) then the backflow shockwave is minimal.

I know it's not called a backflow shockwave, but it's late, I've been driving all day (600miles today) and dont have the brains left to use the right term.

It's more important to smooth out the exaust ports, finish with a flap wheel and fine grit or a Scotchbrite Cross pad to make it super smooth. that is far more important. If you hog them out only to it a little bit. There is a far larger restriction in the intake side. That's where you need to focus, specifically in the bowl area. Just making changes there and not touching anything else in the heads will make most of the gains. Port matching deliver minimal gains compared to bowl work.

I worked over the intakes on the heads, and My exhaust manifolds are being ported, bead blasted, smoothed over, and re welded by Scott Black on this forum.

quote Originally posted by NickD3.4: It seems a electric drill would have enough power to cut out the ports, that works huh. I'll look into it. Is the "hump" in the exhaust ports you talk about way down in the heads?

right by the spark plug well



You hog it out



And, yes the 3/8 corded drill will operate a 1/4" X 3/8" burr very well and works slower than a die grinder which is safer for an amateur.

Hope this helps

Arn

I don't know if this is too obvious, but I remember exhaust manifolds are larger than the exhaust port to prevent exhaust gases from getting back into the cylinder head (isn't this called revision?). I'm pretty sure you want the header to be larger in diameter than the head. Now, intakes should be as smoooth as possible....

------------------
John DuRette
Custom 85 SE/86 GT
"Kinda makes you nostalgic for a Members Only jacket"

quote Originally posted by NickD3.4: there not on the block, they are off, and getting ready to go to the machine shop. I want to do the work before I send them off for the machining. When you say manifolds, are talking intake, or exhaust?

Exhaust manifolds. Are you porting the Y pipe as well?

Yes the exhaust manifold port should be larger.. than the head port flowing into it. I have learn from reading reports from different flow bench gurus who learn from the flow bench that port matching is a good thing, do not underestimate port match as a horse power producer, flow is the biggest producer of horse power.. flow works like a hose,, you have a large hose and a small hose ,blow thru a garden hose then blow thru a 5/8 fuel line hose feel the pressure from both!!! this is a lesson in port work?? the fin in the intake port is there for a reason.. use care do not open up the ports to much ,do not hog out the bowl to large unless you are looking for 250 horsepower
I have much experience porting but have never ported a fiero V 6..
port matching produces more efficient engine performance and horse power
porting listed in order of importance #1 exhaust manifold & Y pipe or headers
#2 intake manifold upper plenum smooth as a babies bottom
#3 head porting bigger is not better, precision ,uniform ,measured ports all equal
#4 port matching , precise

This post is based on my experience as a shop mechanic,factory trained scooter wrench, paid race tuner ,extensive reading on the subject and years of reading MAD magazine A woman drove me to drink ,,Im remembering her in my will as an expression of gratitude