Exhaust Porting

txsc

Registered User
Getting ready to port a pair of exhaust manifolds. What does everyone use to easily cut the cast iron; stones or cutters? I did my heads with a Dremel and HSS cutters. I doubt this will work efficiently on the iron manifolds.

Thanks,

JD
 
Jerry, I used a stone in a cordless drill, and it took quite a while to hog out those outlets.

Nick
 
I made a Jig that bolted onto the collector and used a 2" hole saw with Carbide tips, then smoothed out the transition with a dremel.

- Dan
 
How about a carbide cutter in a die grinder? I have a 1/4" shank diegrinder that would work, but where to get the carbide cutter?

Nick,

What size stone did you use? I found an assortment at Sears, but thought that a cutter would be better. Worst case, I can go get some stones. I'll use them in my die grinder, so it should go considerably faster than a drill. How many did you go through on a pair of manifolds?

Thanks,

JD
 
I ported mine while they were still on car. I started with a coarse stone, then a finer stone. It really did not take all that long, even on the car.
 
Jerry, the stone I used was 5/8 x 1 1/2", tapered. Only ended up using one out of the two I bought, only hogged out the outlets. Stone was as coarse as I could find in the local Ace Hardware.

Nick
 
Jerry, the stone I used was 5/8 x 1 1/2", tapered. Only ended up using one out of the two I bought, only hogged out the outlets. Stone was as coarse as I could find in the local Ace Hardware.

Nick

Thanks. I picked up a couple at Sears this afternoon. They're about 3/4" dia. x 1" long. Figured the larger the diameter, the higher the surface speed at a given RPM. I'm going to chuck this up in my die grinder tomorrow and have at it. Hope it goes quick.

JD
 
does this really make much of a difference?? anyone know how much?

According to XR7Dave, this makes the 94/95 manifolds flow nearly as well as mid-length headers. For a low-buck modification, it's a good "bang for the buck".

JD
 
94/95 manifolds EGR hook up is different than early model's hook up, I mean early model hook up is on the driver side and 94/95 model is on the passenger side, right?:confused:

Can I make 94/95 model manifolds fit to my '90?

Thanks!

Sami
 
94/95 manifolds EGR hook up is different than early model's hook up, I mean early model hook up is on the driver side and 94/95 model is on the passenger side, right?:confused:

Sami

early EGR is from the passenger side. my 89 hooks up from the pass. side manifold.



TXSC : How far are u openging them up ?
 
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According to XR7Dave, this makes the 94/95 manifolds flow nearly as well as mid-length headers. For a low-buck modification, it's a good "bang for the buck".

JD


so its the 94/95 manifolds.... so if i port out my 89 manifolds it wouldnt do much?

if i would have to swap the maifolds to a 94-95 why worry abolut the EGR.... just make an EGR delete... its easy and i saw a nice one for sale for lke 25 bucks!!!
 
so its the 94/95 manifolds.... so if i port out my 89 manifolds it wouldnt do much?

if i would have to swap the maifolds to a 94-95 why worry abolut the EGR.... just make an EGR delete... its easy and i saw a nice one for sale for lke 25 bucks!!!

Porting the 89-93's will also help; they're just not as good as the 94/95's. Actually, you only need the RH (pass side) 94/95. The LH (drivers side) is the same for all years.

Also, you will need the EGR tube from a 94/95 if your earlier car is equipped with it. They are both on the RH side, but due to the collector location difference, the 94/95 tube is slightly different.

If you want, you can delete the EGR, but there are mixed reviews on the benefit of having EGR intact. On the positive side, it helps cruising fuel economy (not active under accelleration). On the negative, you'll likely need to find a '90 engine computer to eliminate the CEL. Some get the light, others don't.

I just went through all the research, and elected to leave mine intact.

Good Luck,

JD
 
early EGR is from the passenger side. my 89 hooks up from the pass. side manifold.



TXSC : How far are u openging them up ?

All EGR tube connections are on the RH side, regardless of year. The attachment point is slightly different on the 94/95's. I'm not sure you couldn't modify the early tube to work with the later manifold if you wanted to cut and microweld it back together.

I opened up the manifolds enough to eliminate the "lip", and blend smoothly into the walls of the manifold. I'll measure one before I put it on to get a dimension. However, whey you start grinding, it will be apparent how much to take out. Others have opened them up to the point that the sealing flange was nearly gone. For this, I'd rather have CNC equipment, since that'd be a lot of grinding. Also, for my relatively stock engine, grinding out the flanges is good enough.

JD
 
hey txsc, do you have any pics of the head side of the manifolds, did you port each pipe where it bolts to the head or just the collector side?
 
FYI, the passenger side manifold has a different collector angle on the 94-95 cars. That means you need to modify your downtube (or get a new one) to fit it on an 89-93 car.
 
hey txsc, do you have any pics of the head side of the manifolds, did you port each pipe where it bolts to the head or just the collector side?

I only ported the collector side. Per advise from XR7Dave, I left the inlet side alone.

For the record, my outlets now measure 2" diameter.

Regarding RH manifold; That is correct, the collector angle is different. Since I'm having a new set of cat-less down tubes fabricated, it's not a problem for me. If you are going to leave the factory cats intact, you'd need to get the RH down tube assembly from a donor car, and splice it in. However, the best bet for those who want (or need) cats is to have a set of new down tubes fabricated with some good flowing aftermarket cats.

JD
 
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