camaro1992

I don't know much about what numbers mean when looking at something. I am interested in getting 250-300hp out of my 305 without going into the motor. It is weak and needs a lot of help. What would I need to look at doing to try and achieve this? If 250-300 is too much without going internal I will take what I can get. Any suggestions?
Thanks

Jproz1167

iTrader: (3)

Get a set of headers and better exhaust system. An edelbrock intake manifold wouldn't hurt either & some lower gears. .... Aside from that Don't expect much out of the LO-3, the heads and cam suck

robertfrank

iTrader: (27)

Exhaust, 463 aluminum heads, ZZ4 cam and any matching intake, 3.42 or 3.73gears and with tuning should get you close if not there.

Jproz1167

iTrader: (3)

I'de go no lower then 3.42's mine has never done very good with 3.73's but then again maybe a automatic would run a bit different. Forgot to mention a better flowing air cleaner setup would help. I've read the stock air cleaner chokes a V-8 pretty good. But exhaust is the first thing I would do since the LO-3 is choked badly by the stock system. Even if you put a TPI exhaust on the car it would help.

Without doing the exhaust, gears, intake ... going into the motor would be pointless. I think with just a good exhaust and TBI mods and an edelbrock manifold and a better ecm chip you'de see at least 210hp.

FreeLoader

actually it's sort of in the middle, the cam and the exhaust manifolds need to be changed first to make any real gains, then from there everything starts making real power.

and you pretty much can't make 250 hp without digging into the motor, you could probably get to 210-220 though.

fabricate a cold air/ram air intake, or just go open element, change out your ENTIRE exhaust(specifically the headers and y-pipe, they'll give the most gains) and start prom tuning.

everything else is fluff, those 3 things will make you all your power...outside of the motor.

oh, and while changing the rear gears won't make you any horsepower, if you're just looking for trap speed reduction or seat-of-your-pants power, that's the best first step you can make if you have a 2.73. just make sure whatever it is, is limited slip.

golden

By the way if u change your rear gear just make sure of the size you have : 7 1/2 or 7 5/8 ... I made a mistake on this one .

ShiftyCapone

iTrader: (7)

I will also reiterate the importance of a new exhaust system. You want to replace everything from the manifolds back and replace them with aftermarket components tailored to post 1986 TPI systems (Everything will come 3" without reducers). This should be the first power mod (gears/posi and SFC's should be your first suspension and drive train mods). Without nitrous you won't hit 250hp without going internal. However, you can hit that with a cam swap and tuning only (assuming you have the exhaust mods). The stock heads are fine and will easily support your power goals in stock untouched form. Those who say otherwise are just regurgitating hearsay. Although a cam swap is going internal, it is relatively mild and a used LT1 cam (when tuned will hit your power goal of 250+hp) can be had for less than $50. Without the cam I will agree with FreeLoader that 200 to 220 will be your limit with bolt ons only (even at that an intake manifold is considered internal by some).

FreeLoader

I agree with the entire above statement, except for two things(assuming you were to change the cam, that is):

1. you're gonna need more fuel. more than your stock pump/injectors could give you, more than likely. regardless of tuning.(again, this only really assumes the cam change, you can get away with the external stuff on the stock fuel setup)

2. while you can get an lt1 cam for $50(assuming one is for sale on ebay), shifty's own sticky mentions several other parts that also should be changed, such as valve springs, timing chain(if needed), and various new seals to close the engine back up. while you can get away with a cam change fairly cheap, you're still talking about around $150 for a cam change, and thats with you doing the work and changing the minimum parts neccessary.

otherwise, assuming you're not changing the cam, then yes. I agree with everything above .

BMmonteSS

Just like to add that Fast355 has made big power on stock injectors with higher than stock FP. Of course the stock pump will have to be changed in order to run more pressure.

Being able to tune the chip will open the door to a lot of options.

FreeLoader

that's actually what I meant, the pump would be the first and most important change, a good long while before injectors. although you could get away with bigger injectors and keep the same pump, I'd much prefer to do it the other way around.

camaro1992

Well it sounds like I just need to do any exhaust system, and maybe intake. I am going to start looking after I do this for another 305 to build. I will cam it, and use other internal suggestions. Why build a 305? I want to keep my vin number true as much as possible. So shorties or long tubes, what brand, what is a fairly priced cat-back system that sounds good? Sorry so many questions guys.

AssCloud

300 will be very difficult out of the 305. definately easier to drop something else in there. cheaper also.

FreeLoader

if you're handy with tools, building a secondary 305 can be fun. you'd be suprised what you'll get away with on close to stock parts.

but, before you go running for exhaust and other parts, get setup for tuning, seriously.

if you do your homework, and look around everywhere, you can get setup for it fairly cheap, but you're sorely regret not doing it if you sink any real money into that motor.

that being said, long tubes are generally understood to be the better power makers(considerably, actually), but are far more of a hassle to install. I'd stick with the shorty type that most companies sell specifically for thirdgens. also, make absolutely sure they're ceramic coated at least, or they'll discolor, rust, and not flow as well, not to mention not retain their heat as effectively as the stock cast ironer's(which can cause various annoying and misleading issues). if you can get one that comes with a y-pipe, go for it. looking for a completely seperate aftermarket y-pipe that lines up with whatever headers you got can be a pain. also, some y-pipes that come packaged with headers also have the ceramic coating, which is nice.

for the catback, that's all personal opinion, do some searches, find an exhaust note you like, and buy that one. in the end no matter what catback you choose(assuming its performance aftermarket), the power differences will be negligable.

as for companies specifically....well for the headers, I hear hooker is the best price/performance ratio around. hedman is cheaper, but from what I read, you get what you pay for. oh, and don't go less then 1 5/8's of course, in fact you may want to go bigger. I'd go 1 3/4's personally.

and for catback companies, personally I really like dynomax. they don't make the biggest pipes, but they flow very well, they're dead quiet until you romp on it(reducing the amount of tickets your liable to get by a lot, honestly) and they're extremely affordable. they're also stock replacement, so it should be an easy install. some other options would obviously be flowmaster, cheap easy and big(though personally i don't like the exhaust note), mufflex has a 4" diameter catback, it's the biggest I'm aware of. random tech and borla both have really really good sounding catbacks, but they're both very expensive, especially borla, at something like $800 for just the catback.

as for digging into the engine, an extremely sneaky move you could do would be to port/rebuild the stock heads(with better parts, SS valves and whatnot), port the stock intake, switch to the LT1 cam, and do a basic rebuild otherwise. I would upgrade to hypereutectic pistons(which come with 90% of the rebuild kits out there that include pistons) and a better than stock crank(preferrably forged), if you have the dough. it's not neccessary, but the long crank undergoes a lot of stress in 305's, and the stock ones are cast iron, so cutting weight and strengthening that perticular part wouldn't hurt at all. also, that build is actually a decent candidate for the holley 670 tbi, if you'd be interested. anyway...all of that together would make for a very mean, utterly stock looking engine. with headers.

oh, and ALLLL of that aside, if you want to make 250hp on that car, you WILL want subframe connectors FIRST! very important, you'll thank shifty later for mentioning it initially.

sorry this was so long.

camaro1992

Thanks will definably print that out. I don't think that I want to mess with the motor I am scared that things will start leaking. I just want a good sound and little bit more power for now. Another reason I am going to build another 305 I can use the headers and exhaust for it. What kinda homework do I need to do know? Just look at headers and find what sound I want? Sorry for so many questions, I know what I want just don't know how to get there.

Fionnla

Being an old baby boomer with a 85 camaro with 89 L03 with 3.42 posi, I took advice from Techs on this web site and my Hillbilly mechanic who races. I went to the junk yard and got a set of TPI exhaust manifolds, (don't like after market headers becauses of leaks if you drive in the weather much). I had 3" pipes installed, along with a new good fuel pump. an open element air cleaner, and a performance chip. I also did a tuneup on the Ignition System, and rebuilt the TBI.
The car went from a dog to perky a little raskel that looks good, sounds good, runs great, and is a joy to drive.
I don't have a clue of how much HP it gained, but it gives my buddie's 89 TPI bird all it wants for breakfast now where before he would clean my clock pretty bad. The word I get from Nerds in the know is that the money I would have to spend to get the L03 to run much better, I would be better off going the 350 route.
Good Luck Bud...

FreeLoader

actually, your pipe size and choice of muffler will give you most of your exhaust note...a simple catback change can make a large difference in the way your exhuast sounds.

most exhaust companies websites have recordings of their various products on various cars...listen to all of them to get an idea of what sounds their products produce, and stick to the car engines with similar dimensions (specificially v-8, cube size and bore/stroke ratio) to get a more specfic idea of what yours would sound like with their parts on your car.

borla, flowmaster, magnaflow, and mufflex all have them I believe, I think dynomax does too.

another good idea would actually be to go to the exhaust board of these forums, they can get into the real specfics of this and even give you links to whatever exhaust they used on their specific cars, many of which are 305's.

the stock tpi manifolds are considerably less abysmal than the tbi ones, but I wouldn't say they'll make you much more power. the good news is they're a much simpler change, assuming none of the exhaust manifold bolts are broken or stripped.

which reminds me, regardless of what you do, if you do remove the stock manifolds, do yourself a favor and replace the bolts on them with at least new ones, possibly even with grade 8 bolts. the old ones will assuredly be used, warped, possibly even break on removal. also, exhaust bolts are known to come loose over time(causing an obvious exhuast leak), wheras grade 8 bolts from what i hear greatly reduce this chance. it's a worthwhile investment.

as for intake, spark, even fuel...most intake setups(as long as they aren't the stock one) will flow so much more air that you'll notice a difference. spark is the same story(in that whatever one you choose, it'll be an "improvement"), though most people by default go with MSD or accel, I went with MSD myself, though I can't say it made much more difference than the car running a bit smoother and having a nicer pedal response. fuel...we've pretty much covered fuel. nothing too crazy there.

another thing you may want to look into drivetrain improvement, and suspension/frame improvement. both can actually make your car go faster, turn better, as far as actually driving the car, those two things can be as effective(in some cases more) as anything you can do outside the motor to improve performance. the biggest improvement I've ever had with my car was rebuilding the front suspension with polygraphite bushings and the spohn strut mounts, while the car didn't neccessarily accelerate faster, it turned so much better and held speed so much better, that it just...it was like owning a whole new, better car.

ShiftyCapone

iTrader: (7)

Agreed



No need for grade 8. They seal no better or no worse than any other bolt for this application. If you break a grade 8 bolt in a manifold you have greater problems to worry about than the exhaust (shear strength of a single 3/8" grade 8 bolt can be up to and over 10,000lbs). Stock replacement exhaust manifold studs and bolts are more than strong enough with a little dab of thread lock-tite to keep them anchored. Same goes for headers and a set of quality aftermarket stainless header bolts (Breslins and stage 8 are pretty good). When it comes to header bolts you pay for material and mechanical locking features. Strength isn't really main criteria.