95 SW2 intake / exhaust questions

Hey guys,

I have a 95 SW2 with the DOHC and auto transmission (no room for CAI). I'm waiting for my Short Ram Intake to arrive in the mail, and while waiting, I've been doing some thinking and reading in the forums here.

First off, I'm thinking about some sort of hood scoop/ram air action on the hood on the driver's side near the front. Something low-profile, just above the cone filter of the SRI.

My idea here is that the air will rush in and get ducted right down over the filter element. I don't plan on merely cutting a hole in the hood under the scoop, but also add a curved metal or plastic sheet between the battery cover and filter to help direct the air once it goes into the scoop. If this setup will work out, where is the best place to relocate the Intake Air Temp sensor?

Any thoughts/ideas/warnings about this? I plan to get a spare junkyard hood to modify, rather than risk botching my nice matching-colored one. Once I have finally decided whether to do any kind of body accents, I'll be doing a full body graphics wrap on the car, including all the windows rear of the front doors. Therefore a mismatched hood won't matter, but at least I'll have the original just in case.

I would also like to know what will work well to insulate the aluminum SRI pipe against the heat of the engine and radiator hose. Gotta keep that intake air cool, right?

Second, I guess I need to think about exhaust since I have the intake covered. I have read that the exh. manifold from a 91 or 92 DOHC will bolt right up to my engine, but that the downpipe must be welded to the cat. Can't I just use the 91/92 manifold but keep the 95 downpipe? Will it match up?

If it can be a straight bolt-on, I'll do it gladly. However, if welding is involved because I'm required to use the 91-92 downpipe with the 91-92 manifold, I might just hold off and stay stock 95 till I can do the entire exhuast system, including the 91-92 manifold, downpipe, a new 'universal' cat and full catback exhaust with 2.25" stainless and a nice muffler.

What solutions have you post-92 S-Series DOHC guys come up with? I honestly don't see the point of aftermarket headers when the cost differential is so big with only minimal gains over the 91-92 manifold, especially if I'm going to have spring for a full exhaust.

Once I get this all straightened out and wrap the car, I'll put up some pics. I sure am lucky to work in digital printing!

Thanks all, can't wait to hear your thoughts.

______
ilxebius

dont mess with trying to do a hood scoop, it just wont work out. the best way for anything to work is to remove the headlight, which isnt a possibility. other then that, you have to make a custom set up from the fog light hole or front opening on bumper and up to the filter, which still isnt worth it. you will get very minimal if any gain. like i said the best way is just to pull the headlight off.

intake wrap, you can buy exhaust wrap and that should keep radiant heat out but that stuff can get expensive.

now the 91-92 exhaust manifold is a 4-2-1 style, yours is a 4-1, so you must use the 91-92 downpipe. and yes it will work out fine, but will need to weld. getting your hands on a 91-92 manifold is best because itll be cheap, otherwise like me you will have to spend quite a bit more to get something similar.

Just an FYI update:

I installed the Short Ram Intake this weekend, and opted to zip-tie the IAT sensor to the bracket next to the filter rather than buy a tap-and-die set and go that route.

Keep in mind I have the automatic transmission, which I would drive with the NORMal setting. I noticed with the new intake that the car was slower to pull up the revs, unless I mashed on the gas and forced a downshift.

I remembered reading a post that said the PERFormance mode does more than just rev each gear higher before shifting, including adjusting gas flow, spark, etc. by the computer.

Well, I switched over to PERF and the car 'drives right' again. My theory is that under NORM mode, the engine was getting more air than it should expect, and not compensating with more gas. Switching to PERF gave the engine more gas to match the added air, thus balancing things out.

Am I on the right track here, or way off in left field? I'll continue to drive in PERF and wait to see if my fuel economy takes a nosedive. I certainly hope not, since one of the advantages of a cone filter in open space is supposed to be increased fuel efficiency. That's how they market them, anyways.

I'll continue to drive my usual way for the next couple tanks of gas to find out. I know I'm only gaining 0.75-1.5 HP with the SRI, but honestly I just did it for the allegedly better mileage...and the throaty sound!

Next up will be a full exhaust, including the '92 exhaust manifold, downpipe, new 'high flow' cat and new pipes and muffler (cat-back). Obviously I'm not getting a turbo on an auto, and I won't give up my power steering or A/C for a supercharger. So keep in mind NA for exhaust. Any recommendations on piping size, brands, etc?

I know Borla is good, but a bit pricey. I'd also like a muffler that growls but isn't obnoxious. And I absolutely want to avoid the gay sound of a fart can with a 6 inch wide tip (ie. those horrible bombz cans on ebay)! As far as looks go, I think a 2.5 inch exit pipe will do nicely.

Thanks
______
ilxebius

ok the performance mode is supposedly suppose to raise the shift points, which i never noticed when i drove one, and increase line pressure so you will probably feel a harsher shift. it does nothing to the engine, its all for the trans.

now exhaust size, i would definitely keep it below 2 1/4". im running a 2" high flow cat, n1 muffler, and a short glasspack resonator. this combo is pretty good but it does get the "ricy" sound when cold and under hard throttle or high rpms (when i hit 5K and above you start to hear a whistle almost like a turbo spooling). i would suggest putting the longest resonator on it as possible and use a magnaflow muffler to be it sounding good. this all means, no catback. there arent very many choices anyways, and going custom can be alot cheaper. also to cut down on some raspy sounds, maybe even pick up a resonated tip.

also the reason for the longer resonator typical cuts down on the raspy sound. it doesnt affect flow much at all because its a straight through design and its main reason is to cut down on noise, so longer the better.

true about performance mode, no change in the fuel trim(maybe a hair due to change in engine load, but regardless...)

your block learn will take a couple of days to adjust for the intake. if your normally drive in NORM not PERF, then stay in NORM. the PCM relies on the MAP sensor to measure air flow not the little switch by the shifter.

before adding the exhaust, fix the IAT, or the improper A/F raito will make everything else worthless.

go with 2.25 mandrel or 2.5 crushed

Ok, so the IAT sensor is sitting between the cone filter and the battery, away from the radiator hose. How much different would that air temp be than if the sniffer was poking into the pipe behind the filter? I'll eventually tap a hole, but in the meantime is it really going to be way off?

Can anyone tell me the thread dimensions for the IAT as well? I could just maybe stop by a machine shop and have them tap the hole for me on a lunch hour or something. Any particular location preferred, or just somewhere behind the filter?

Also, I got useless instructions with my SRI. It was an ebay special and the brackets that it came with are a mystery at best. The reducer it came with wasn't small enough for the TB, so I had to go to Autozone to get a 3"-2.5". It seemed a little big, but smaller than the one I got with the SRI and it clamps down tight all the way around.

Could any of you with an SRI post some pics/instructions for bracket locations? I have improvised them for now to prop the filter up by its metal lip to avoid contact with the radiator hose, but I'd like to do it the right way (aside from the right way being to buy an AEM kit, heh).

As for the exhaust, what material are the manifold and downpipe from an '02 DOHC? I was thinking of an aluminum exhaust for weight and no corrosion, but I imagine all elements of the exhaust have to be the same metal in order to weld properly.

As for the resonator, I think I need to do some more reading. I always thought the resonator was to insure silent exhaust coming out of the muffler (like a pre-muffler muffler)...something I don't want. Guess I had that wrong, heh.

I totally get the catback thing now...just another term for bolt-on. Guess I'm going custom! Is the stock pipe routing good enough, or is there a better way to go? I guess I mean to ask if the bends and turns have any effect on performance. I can only assume mandrel bent is the way to go, assuring smooth inner surfaces for better exhaust flow. The term crushed implies crinkly areas inside the pipe. Please correct me if I'm wrong.

I've decided so far on a 2" system with the tip at the end being 2.5" for looks. But the exhaust won't happen until the summer anyhow.

Thanks guys for all the great info!

i don't know how for off the IAT reading will be. but trust me, when it come to performance, cutting corners just doesn't cut it. not to say i haven't cut a corner here or there, but i always paided for it later. i cut a corner installing my intake, i drilled a hole for the IAT but didn't tap it. instead i got wrench and jammed it in there. result: in stayed in there, but the threads are trashed. if i ever remove it it will need replaced, plus it might have leaked a little bit of air. and place the hole where it won't hit anything(i almost place mine to high where it would have hit the hood).

those brackets are most likey designed for use on a muitsubushi eclipse. the designs are so simular, some manufactiors just list the eclipse intake for saturns. you may want to custom fab some brackets. spswebpage.com also sells a bracket

i beleave the manifold is steel, but you are doing a cat back right?if you are worryed about the welds use flanges and bolts.

both the resonator and muffer reduce exhaust noise, they just reduce different types of noise.

and unless you want a side or dual exhaust(i don't think you do) the bends are fine, just make sure the exhaust goes OVER the rear suspention. mandrel is more expencive and harder to find.

there is no such thing as an aluminum exhaust. to make it *work* it would weight ALOT more then aluminized steel or stainless. if you have the money go stainless, if not aluminized is what is normally used. now if you can really get the money, have the pipe ceramic coated. also aluminum is what corrodes.

yes the resonator quiets the exhaust, so the bigger the better and saturns can get pretty raspy with and opened exhaust, so get a pretty good size resonator. have the exhaust routed the same way as factory. the stock manifold on all saturns, but the 91-92, is cast steel.

now about the bracket, if its like mine, it will bolt up to the bell housing to engine stud (one closest to the coils with grounds attached). i dont have a picture, nore can get one since its dark.

now the iat. get a bit or hole saw the size of the threads on the iat, just a hair bigger. now drill a hole in the intake, a spot where it wont interfere with anything else. now you will need a rubber grommet to go around the hole that will make the iat fit in snug to the intake. thats what i did.

First off, thanks for the great info so far...

the stock manifold on all saturns, but the 91-92, is cast steel.



Well, I am looking for a 91-92 DOHC exhaust manifold to put on my car. If all but 91-92 is cast steel, what are the 91-92 manifolds made of?

I like the idea of using flanges and bolts, which I assume will require some type of gaskets. This method would allow me to change exhaust pieces if needed without having to cut and reweld. I guess everything will come to light when I actually go to an exhaust shop this summer and have someone evaluate the car.

I went to spswebpage.com and looked at the powerstack bracket. Should be able to make one of those for a lot less than 49 bucks, heh. Looks like it bolts to the two holes by the battery where the stock airbox bolted and supports the tube just behind the filter.

I also saw those crankcase breather filters, which would keep oily warm air from getting into my intake tube. Would you guys recommend them? Or will they fill with oil and dribble all over the place? I know they are nice on V8s, but many of those breather hose nipples are pointed up instead of sideways like the Saturn. If it turns out these are good to get, I can probably just cap the nipple on the intake tube with a vacuum plug.

Back to the IAT, where would be a good place to find out the thread dimensions?

Again, many thanks guys. After I get the car inhaling and exhaling right, I think the next step will be one of those bored throttle bodies. They seem like a good deal at $129.

91-92 are tubular steel, just like you find on aftermarket headers.

the breather is a toss up, i think on the saturns there havent been issues with it dripping oil because there is a baffle on the bottom side of the valve cover to keep oil down on the cams. ive had cars where they leak like crazy, so i just dont use them, of course you can always add a catch can before the filter.

the iat, you can go into a hardware store with it and do like i did and find a holesaw (circular looking saw) that fits perfectly over the iat. then find a grommet that fits tight against the iat threads and will fit within the hole, and do it that way. otherwise you get to deal with finding the right thread pitch tap, and at that size i bet it will be a bit expensive. ive dealt with taps and dies, and the little tap i used on my friends valve cover cost about $8 for a 1/4" in size. then had to buy the tool to cut the threads. i use taps, but in this case just go with the grommet.

my breather leaked oil...IMHO the PCV system is one not to be taken likey. many people do buy the beathers to "keep oily warm air from getting into my intake" well on a properly running engine the only time air will flow from the crankcase to the intake tube is at WOT, the rest of the time air is flowing from the intake to the crankcase. i could keep going on but trust me, its not worth it.

for the throttle body - http://www.qksltwo.com/tb.html

The DIY throttle body boring in that link makes me a little nervous. Aside from my paranoia about errant metal shavings in a nook or cranny despite thorough cleaning, dremelling around the opening doesn't seem very precise.

Does it matter if the hole is not perfectly round? If not, I'd consider picking up a spare TB from a junkyard and working it out, all the while having my original TB just in case.

If your breather leaked oil, I'm guessing that means your gas pedal spent a lot of time mashed into the floor? LOL Thanks for sharing your experience. It'll keep me from having to go through it. :)

Today was a slooooow day at work, so I got to do my homework on exhaust components. I think I'm going all Magnaflow for everything, since their product line seems to be the most complete I've found that will work with my Saturn and at reasonable prices.

After doing some research, I have deduced that the 91-92 exhaust manifold and downpipe end up with a 2.25" outlet for the CAT. From that point, I decided all components will be 2.25" to remain consistent throughout. No problem, since Magnaflow has 2.25" everything from CAT to tip!

I did notice, however, that my stock 95 exhaust has a long downpipe and flex section, leading to the CAT, which is a bit under the passenger compartment. There is a direct-fit replacement for it (2"), with a diagram showing this. Well, I next looked up the direct-fit CAT for a 92 SL (2.25") and the diagram merely shows the cat with flange, but no big ol' pipe and flex section.

If I were to put the 92 exhaust manifold and downpipe on my 95 SW2, would the CAT be in the same location, or would I need the shop to recreate the extra piping and flex section? I actually plan on getting Magnaflow Part #91005 universal high-flow CAT, not the direct-fit since it is cheaper.

Next question: Does the 95 SW2 have an o2 sensor on the CAT, or is it unmonitored? I can't get that far under the car to see. I did notice the o2 sensor right in the middle of the 95 exhaust manifold, though. There is another universal CAT, Magnaflow Part #91035 that has an o2 sensor bung, if I need it.

Once I have that figured out, I have narrowed down my resonator choices to an 18" (Magnaflow #10425) or a 22" (Magnaflow #10435). I just don't know how the length of the resonator affects sound. I want to eliminate raspiness, but I don't want the lower pitched growl to suffer. If I go through all this and end up with a car that is quiet as stock, I'll be upset...unless I still get the power gains...then I guess I'll be on my way to tuning a sleeper! Oh and yes I do realize noise does not equal power. hehehe

The muffler I think I want is the Magnaflow XL 4x9 offset/center satin stainless muffler, part #13215. The body length is 14" and overall is 20".

Forgive my verboseness, but I figure the part numbers will help you all to see what I'm looking at and tell me if I'm making the right choices. Plus, anyone searching through the forums may be able to benefit from this info as well.

Thanks

You know, this all started when I bought an SRI on ebay to get myself a K&N filter for little more than the price of a paper replacement filter. My wife is going to have fun when I buy myself a 5-speed and she gets this car!

well boring out your throttle body normally means boring both sides and have it taper to the throttle plate, otherwise if its not perfect on the throttle plate seat, then it will cause issues. its easy to bore it, you just stop at the throttle plate on both sides. sure its not as great as getting a full port with a new plate, but it ensures you wont have an issue.

now the 95 is ob1, so only 1 o2 sensor. but go with the 22" resonator. you should be happy with that exhaust, but having that smaller tip might cause some raspy noises during certain throttle.