Ok so I was just wondering what some of you guys would do to this car? I am shooting for about 350 - 400 hp without NOS. The engine looks stock but very well maintained. Havn't had a chance to take it apart to look at it in depth. At this point money isn't really a problem I just need to get some ideas. Anyway thanks for the info in advance.

 

Your power goals are pretty much unattainable with a 305. I like the 305 but it's just not a realistic goal. The L03 can be worked into a decent performer though and hold its own on the street. I recommend starting out with the exhaust. Headers, high flow cat to a aftermarket cat back.

 

hmm I wouldn't think that it would be totally impossible to do. But I havn't spent a lot of time researching it. Are there very many good supercharging or turbo kits for this engine?

 

One of the main reasons that 400hp is out of reach for the 305 is the fact that it is a 2 bolt main. It just won't withstand that much. 300-325 hp is possible though I believe with the right speed parts and lots of tuning. Basically, you are going to have to re-work the entire top end of the motor. Heads, cam, intake, throttle body, injectors... all of it wil have to come out. You might as well junk the heads and find some nice ones to go on there. If you are going to run boost then you could find some with 64cc combustion chambers to lower your compression a little. Vortechs are nice, but require some work for anything over .48 lift. You are also going to have to put a full exhaust on there. Either the Hooker LTs with duels or the SLP shorties with 1 3/4 primaries and a 3" catback would be good choices. Turndowns after the LTs would be great, but I dunno if you are keeping this thing street legal or not.

I used to hate the "just get a 350" argument, but in all honesty there are a lot of reasons to go with more cubes. A 350H.O. crate motor can be had for $2200 which is not a bad deal at all, and it will be in the 330hp range already without forced induction. You will spend more than that just getting a blower on the 305, not including all the work you'd have to do to the top end AND you have to consider how many miles you've got on the short block. You wouldn't want to do all that to a 305 just to have a piston, rod, or rings fail 6 months down the line.

Damn, I'm depressing aren't I
Harry

 

Read my sig. and you will know what to do

 

Hmm interesting, I had thought about buying a new short block for the car then building that up slowly. It is probably a good idea to do it anyway. The main reason why I didn't want to get a crate motor is because of the amount of initial cost for it. I would rather spend 300 - 500 here and there rather then try and come up with 2k - 3k all at once Guess I can start checking out summit for some parts. Thanks for the help.

 

a two bolt main has NOTHING to do with horsepower capabilities up to around 400hp regardless of the motor you're running. I've seen 450hp 400's with 2-bolt mains. Period.

TRP

 

Are you kidding?

 

Really? Hmmm, I've never heard of anyone running 400 or more horses on a 2-bolt main, esp. if it's a screamer high-winding small block. I'm not doubting you guys, that's just what I heard growing up. I'm 23 and I still learn something new about these machines every day. Guess that just goes to show how far a false assumption from your childhood can carry.

Later,
Harry

 

for power anything near that, you need to swap in a motor with a larger bore.

a 350 could get you there, and a 383 or 400 block could get you there even easier.


fact is, currently your car is like this:

the air is sucked in thru a thin snorkle where the restrictive neck is even more restrictive by a small butterfly valve... the air must then flow up thru the thin aircleaner where after passing thru it, it must make a sharp 90* turn down the throttlebody... the throttle body, even with out this aircleaner restriction, only flows 450 somthing CFM.... the air/fuel mixture then goes thru the flattest cast iron manifold that ive ever seen.. this manifold is so low that the air must make a sharp turn just to get to the port on the head. once there, it must pass thru the ****ty intake ports and around the tiny valves..... but the valves are halfway shrouded anyway by the small bore of the 305.... the 305 then uses its TINY amount of compression to try to extract some power from the raw fuel dripping in it, but alas, the stock timing is set at 0*, no where near where it needs to be to make any power. the exhaust now must flow out the ports, still shrouded by the bore and restricted not only by the valves and ****ty exhaust port, but by the small cast iron exhaust maniflolds... after passing thry the manifolds, it has to flow thru this TINY y pipe where it comes together in to a pipe that is still far too small for even the measly 305... it then pours into a cat... and after all these years of running like ****, of course the cat is partially clogged.... from there it goes thru the rest of the exhaust.

the power coming off the crank of course, well, it gets dropped a good bit just by the old struggling 700r4 behind it.... and the 2.32s in the pegleg rear really dont help it off the line. and lets not forget the other end of the crank... where it seems like about half of the meager less then a honda 4cyl power that it does make is sucked away turning the waterpump, alt, PS pump and ofcourse..... the smog pump.





dont you just love owning a l03 3rdgen?

 

1Mean92RS - (Or Thundercat as I shall now refer to you) - the mains of a motor have only a limited influence on its capabilities. I was taught at the machine shop I worked at that up to around 500hp you're ok with a 2-bolt block as long as you build a stout bottom end (ARP studs/bolts and a good balancing job). Above that the 4-bolt does help out, though some have made the argument that the 4-bolt arrangement weakens the block's main webbing and therefore, a 2 bolt is actually stronger. If you want a definitive answer - read Smokey Yunick's book "Power Secrets" - he's a pro and doesn't give any bad advice. Everyone on the boards is well intentioned, but not always well informed. Happy driving.

Tyguy

 

heres a list of what i got on my car

headmann headers
2 flowmasters 40 series
high performance coil, cap and rotor from accel
open elemnet with k&n filter


and trust me this made so much diffrence in my car, and your looking at 560 dollars only good deal

 

hey guys

On the subject about 2 bolt mains. how about a buick GN they have 2 bolt mains and they cna survive alot lot more thatn 350 hp
without a problem.


On a 305 making that kind of power. i don't think the block or crank will be a problem. If it bothers you can get a griddle on the bottom end that bolts the entire bottom end together so it can't move. aith some arp studs nah it's good for 400hp if the top-end can flow that much air for that hp.

 

If you want peace of mind ,just replace the main and rod bolts with ARP bolts, or change to studs.

 

hmm ok, so the 2 bolt main should not be a problem to make 400 hp out of the engine. The big problem is the air flow? atleast that is how I understand it. So I think for the first mod I will try and get rid of that crappy snorckle thing and replace it with an open element K&N air filter. I am sure they make kits to do this right?

Also does anyone know if the throttle body for a carburated 350 will work on the TBI 305?

 

To make 400hp out of a 305 TBI you are going to need a helluva lot more than bolt ons like that. An open element is like a given. It's going to cost you Huge money to come up with that kind of power out of that 305, and not to mention that 400hp is really yet to be achieved with TBI. It will take a Lot of prom tuning and trying to figure out which injectors to use and at what pressure to run them. For all the time, work, and money it will take you to achieve this goal with that engine it just isn't a wise choice.