EVH-SETH

Trying to get my newly acquired v6 Camaro back up to factory running condition. It doesn't have redicilous high mileage, and I just want to know what my goal should be for trying to restore gas mileage.

Any helps appreciated
Thanks

//<86TA>\\

iTrader: (14)

the 3.1 i believe is factory rated for 19/27 i assume the 2.8 is similar

batsibf

when i had my 2.8 running it was around 17/25, it was stock at the time. the suppension was worn out and a few other things.

EVH-SETH

SERIOUSLY?? Im getting like 10-15.... i guess thats good news though. all things can be restored.... Dang.

coolrimsatleast

Depends on your driving. When I had a 2.8, I averaged 28-29mpg highway and city combined. 33 freeway.

now I'm getting 27 with a 3.4. I'm having issues at the moment so I'm getting probably 25. I can just barely squeek out 30 or 31 on the freeway.

Rain, cold wet weather, and winter gas hit me pretty hard though too, which is why I'm hovering around the 25 area. My cat is taking a dump too.

EVH-SETH

Yeah my cat is already shot. I need to get some exhaust work done but i don't know what. Ive done a 75% tune up, plugs, oil, o2 sensor, now i need to do rotor cap and plug wires. Think any of these would help a BUNCH?

KrisW

iTrader: (5)

My 216k 1988 2.8/5-speed Firebird gets nearly 30 highway, 20 in town.

A light foot and a good tune up will go a long way. My biggest pain with these V6 cars has been the ignition coil so far. I have had that coil actually corrode through and start partially shorting out to the coil bracket. I can only see the tracking in the dark, but running it at night with the hood up can be very revealing.

Coil, cap and rotor, and plug wires will have a big impact on gas mileage if they are not up to par.

For exhaust, I always run a cat back and converter designed for the single cat 88-90 350 V8 car. Then I have the y-pipe fitted to the new converter at the exhaust shop. I am thinking that the y-pipe could be improved greatly over the crap design that it is, too. All of that should help mileage.

coolrimsatleast

If they're worn out, yes. Have you cleaned the MAF, air filter, front end alignment, EGR ok, PCV ok, any bad vac lines, TPS ok, checked all the grounds, tire pressure, checked the timing, thermostat, and some others I can't think of at the moment? I'd get the cat done and see how it sounds from there.

I need to decide on a brand and part number and get my cat ordered tomorrow. I'm thinking Magnaflow, but need to figure out the number for a direct fit, and if I want to go with a 2.25 or 2.5. Just got a new muffler myself a month ago, and a couple weeks ago it seemed louder, mileage seemed to drop a tad, then the rattling started, and now it sounds horrible again when accelerating.

coolrimsatleast

I wish I had a 5 speed. I should have jumped on another 89 firbird a few months ago nearby with a knocking 2.8 and a 5 spd for $500.

My ignition component weak-spot seems to be my control module. I even added a seperate ground wire for it straight to the firewall instead of grounding through the distributor to see if it'll last longer.

The stock manifold and Y-pipe got me 28-29 avg. I've got the pacesetter headers now, and the Y-pipe has a much nicer merge if you haven't seen them.

zs&tas

Hi, my 5 speeder gets used very little but cruising does 25mpg, i had an auto with OD and that was much better figure 35mpg easy on 60 cruise.

EVH-SETH

Awesome guys! All things I'll check out. As for exhaust, can I just get rid of the cat? I don't want one, and I'm in a place where they arnt needed. Would that help the flow? Or hurt it?

Firebird_305

A high performance one would be better, but it's your choice if you don't want it. I put a magnaflow on mine along with a magnaflow cat back and I like the performance. I just suffer from terrible fuel mileage. Toooo many problems again!

EVH-SETH

My whole objective here is to maximize gas mileage Sooo... I won't do that

KrisW

iTrader: (5)

I don't think the cat and cat-back system are hurting his mileage, so don't be afraid to use them.

I prefer the V8 flowmaster system and the magnaflow cat seems to be the best direct fit upgrade I have found.

KrisW

iTrader: (5)

Don't forget to really drown the bottom of your ignition module in that heat transfer paste. make sure the bottom of the distributor where it screws down is clean and shiny bare metal, then put a ton of that paste on. The excess will squish out and you can clean it out after you bolt it in. Don't just reuse the old stuff.

coolrimsatleast

For a long time on my 2.8 I was using the stock manifolds, 2.5" Catco high-flow cat, 2.5" I-pipe, and a Dynomax 2.5" muffler. Combined with my other mods I was getting the 28-29mpg avg and low 30's on long freeway trips. It had a nice sound to it also.

Combined with the headers with my 3.4, it's always been too loud under acceleration.

I've been searching posts the last couple days on cats, and have read a few stories about these V6's becoming obnoxiously loud with less power when using a straight pipe. Seems to be a hit or miss modification.

Did that too. I was even trying to apply in a way so no air would be trapped when I squished it down.

EVH-SETH

Good tip. I might look into a cat after all. I just dont want to pay that much if its not needed.

Firebird_305

Yeah my problems are not the converter and exhaust. I believe I'm not running on all cylinders. Def do get a good cat and good cat back exhaust. Well worth the $ and besides a HP gain you will get improved MPG!

coolrimsatleast

Fuel pressure. Forgot that one. Make sure the fuel pressure is good. Bad regulator, leak, clogged fuel filter, or the dreaded weak or bad fuel pump will screw it up.

Maybe have the injectors flow tested too.

EVH-SETH

What would you think if I just put a stick replacement system back on? One from Maremont or similiar? Including a converter of course. I think that should do the trick because I want it quiet but I don't want to lose power or MPGs. Opinions

KrisW

iTrader: (5)

This is just my advice, but I don't see any problem with running stock stuff, as long as its stock TPI V8 stuff.

The V8 stuff is restrictive enough in stock form as it is. I always get rid of all the horrible V6 exhaust crap. Even stock V8 TPI stuff flows well enough to let your V6 breathe a bit better. I bet it will even let you pick up a hair of gas mileage too.

I'd buy a 2.5 replacement cat, pipe, muffler, and tailpipes for an 88 IROC with single cat and a vin code 8 (350) TPI V8. You'll need the muffler shop to hook your y-pipe to the new bigger cat, but other than that its a straight bolt on. That was my first mod to my 90 3.1 Firebird. I got a salvaged complete rust free used 89 Trans Am TPI exhaust. Later I used a flowmaster cat-back, but all the stock stuff went right on. The shop enlarged the y-pipe and put a new flange on the pipe to bolt to the cat. Worked great.

EVH-SETH

Called a local shop or a quote, told him I wanted a similar stock system for a 1987 V8 Camaro, and he said WITH a converter would be $290! I think that's pretty reasonable. Without the converter it would be $140, but I think I should probably get the cat for originality and sound sake.

KrisW

iTrader: (5)

Let us know how it turns out

EVH-SETH

Will do!

coolrimsatleast

With the stock manifolds and Ypipe, 2.5 catco cat, 2.5 I pipe, and 2.5 Dynomax single in, dual out muffler, I had a nice sound and great mileage.

My 3.4 with headers sounded good at idle and cruising, but like a gutless ***** with a fart pipe accelerating. I haven't been happy with the mileage either, and for the last month I've been running a 2.25 I pipe, and 2.25 muffler, and as of yesterday, a magnaflow direct replacement cat. The sound is better, still a little loud if I get on it hard, but better. I can't think what brand the muffler is, but it's pretty raspy if I really get on it.

I have a clicking sound behind the guages that is rpm/load related. I wonder if there's a bad wire and it's somehow screwing up my power and mileage. My car also despises winter gas and cold, wet weather, so who knows.

EVH-SETH

What do you guys mean by Y pipe? I know what it is, but where dies it go?

KrisW

iTrader: (5)

This is the pipe that hooks from both exhaust manifolds, combines into one pipe, then hooks to the catalytic converter.

If that pipe is just a piece of crap, like one pipe with the other just welded to it at a 90 degree angle, then it doesn't flow at all. That makes it more of a "T" really, and not a "Y" pipe.

The evidence for this difference is on the TBI and TPI V8 cars. Believe it or not, if you take a VIN code F or 8 car (305 TPI or 350 TPI) y-pipe and put it on the 305 TBI V8 car (VIN code E) you will see real gains in performance. The manifolds are also better from the other engines. Obviously for your V6, you are stuck with the manifolds that you have until you save up to buy the pace setter brand headers. BUT, you can have the exhaust shop build you a better y-pipe (using a flowmaster Y-transistion, for example) and you will get an efficiency and performance gain. By itself its not much, but combined with a better flowing cat-back you can start to get a little bit here and there.

EVH-SETH

Dude thanks for that great tip, I really appreciate it. I'll be sure to have the shop I'm going to do that while I'm there. Now how does this all sound.

Y-pipe conversion

High flow cat

2.5" piping single pipe

Stock quiet muffler (or an SS type muffler that gets a deep rumble not sure yet)

And then two pipes out

Will this give me a considerable difference to the stick pipe cut off right after the converter?
Let me know if I should do anything else before I take her in. I have till next week. Thanks guys

KrisW

iTrader: (5)

You're looking for gas mileage according to the post, so you are looking at efficiency.

As for the exhaust, order the stock 2.5" cat converter, mid pipe, muffler and tail pipes for an 88 IROC-Z. If its me, I would also either have them fit an IROC Y-pipe to the V6 engine or just have them make the y-pipe. As exhaust goes, that will get you the best mileage.

As for the "rumble," the engine has much more to do with that than the muffler does. I don't care what muffler you put on that 2.8, its not ever going to sound like a 350. I think your best bet is the stock 350 muffler, because it fits perfect and flows better than your original piece did.

Your last mod will be headers, when you can afford them. Then, you'll be on to cylinder heads, intake manifolds, and ECM tuning.

EVH-SETH

Alright sounds good. But what's the difference between what the shop would put on and the Iroc parts? It's such a small exhaust length, is the that much that can change? Like between a 2.5" cat and one from and Iroc? I just don't get the difference. I told the guy to do a stock v8 setup for my v6 plus the y-pipe conversion. I don't get how ordering the exact Iroc parts would make a difference.

KrisW

iTrader: (5)

I was using the IROC as an example. There should be no difference if the guy is giving you 2.5" parts.

The info I was adding was how I would do it if I were buying the parts myself.

EVH-SETH

Ohhhh ok. Sorry dude. I get so confused with this stuff sometimes. It's all very simple but I think complicated. Thanks for the tip on the Y pipe and cheers my friend.

project89

iTrader: (1)

the only way to gfet the v6 to sound good is with tons of mods lol
http://youtu.be/wQJ_EB9LBck