last_

Just thought i would share some initial thoughts on how i am going to do a mild build on my 305. All you pros out there should let me know what you think. I don't want to hear any of this just swap in a 350 crap either, so take those responses elsewhere. I am working with what I have and will be building it piece by piece. Besides that I have a soft spot for the 305, seeing as it is the underdog... In my opinion a wolf guised in sheeps clothing.

My goal would be a stage 1 or 2 build so that I have the power to beat these f'in ricers. And how embarrassing would it be to beat by some honda minivan or something... ouch.

Of course I will have a custom chip to take advantage of the finished engine...

165 degree thermostat too replace the 195 degree one.

k&n open filter top of air case with ram air hood and funnel

underdrive accessory pullies

stroker kit will bump the displacement up too 340ci.
http://www.speedomotive.com/ps-26-8-...crank-kit.aspx

Holley ProJection 670cfm TBI
http://www.jegs.com/i/Holley/510/502-9/10002/-1

the Edelbrock Performer Air-Gap
with a turbocity adapter bored to 2" instead of the 1-11/16th" as well as a possible spacer to encourage even fuel distribution.

cylinder heads:
Patriot
http://www.jegs.com/i/Patriot+Perfor.../2180/10002/-1

cam i have been thinking about:
Lunati 218/218 duration, .458/.458 lift
this is an area that i am truly lost in, as well as the valvetrain in general. there are just so many choices and different combos that after about an hour i said f it and stopped doing research.

And I will be going with either an accel or msd ignition.. not sure which one yet.

And that would be my initial thoughts on the project, let me know what you think. Thanks in advance for your help and or thoughts.

blyth18md

I think its probably a waste of cash. But I wont fight you.

I want to stab that in a 305 for some fun...but at 340 cubes, id consider going even a hair bigger.

http://www.iskycams.com/timingchart....g_chart_id=132

igotta355z28

iTrader: (1)

you dont want to hear just swap in a 350 but your willing to stroke your 305 to almost the same displacement?
yes its been beat to death but a 350 is a much better starting point, the thing that sucks about 305 is the small bore, the bigger 4inch bore of the 350 alows for alot more power potential and larger valves with less valve shrouding.
but ill stop there on that note. next item, do you know the purpose of a thermostat? its to force the engine to get warm. id stick with about a 180-195 degree one....heat is our friend heat makes power to a point, an engine running around 210 is going to be happier, have less wear and be more efficient then one running 160-180.....
and K&N lets in alot of air....and alot of dirt....i wouldnt waste my time with them just get a good paper filter for driving and when u want to race might as well just take off the filter and run filterless cause thats bout what its like with the k&n.....
ill post more opinions shortly........

last_

yeah, i dont know about a hair bigger. i am not very confident in going over 340 seeing as this will be a daily driver and at some point past 340 you start to run out of cylinder wall to bore. not sure how much crank you can jam in there.

thanks for the thought though. and at some point down the line i will want to do a 305 turbo build. this is years from now though when i can truly afford to spoil my camaro. for now she will be a daily driver with some serious scoot.

blp226

Don't let anybody try and talk you outta the 305. It's a good engine! with the right heads and valve train those guys will run hard! Now obviously a 350 has more displacement which in turn makes horsepower easier to get, but the ford guys have been gettin power from the 302 for years, and the 302 chevy in the 69 Z/28 was a awesome screamer. I wouldn't stroke it. Take a page from the 302 69 camaro, put a forged rotating assymbly in it, order a valvetrain made for seriously high RPM power. When you want horsepower there are only a few tried and true ways to do it.

1. displacement= you don't wanna do that because your keeping the 305.
Why stroke it. If you want bigger displacement go for a 350.That doesn't make since.

2. forced induction= turbos, superchargers. Your gonna do that later so
thats out.

3. Nitrous= You could just spray the hell out of it.

4. High RPMs= Your only other option is high RPMs, but you'll need top
internals for it to hold together.

I just want you to go for high rpms cause I've always wondered how a 305 would do with that kind of build. LOL

I did see an article in either Carcraft or Engine Builders where they built 3 "unwanted" engines to see how much horsepower could be made streetable out of a 305, a 318, and I don't remember the ford engine. I do remember they all made over 400hp, and that was with standard no more than a 30 over bore, no strokers! I you can hunt down that article it could give you a lot of info.
I just did a search on yahoo, I punched in "chevy small block 305" and tons of tech articles popped up. I would look up an engine that one of the magazine atricles builds that fits what your looking for. That way you won't mess up with your combo. I always like to benifit from the experience of others. LOL

igotta355z28

iTrader: (1)

will not compare to a 302 chevy, 302 uses the large bore small stroke, where as the 305 stock is large stroke small bore. large bores help with more airflow wich is simply how u make power, since the stroke is the same as a 350 the 305 will rev alot like the 350, but with not as much power. IMO 305 are great stock motors for moving around vehichles dependably, they make good torque for their size and they are just great but for all out performance its a bad choice to start with....ever wonder why the ford 302 can make so much more power then the chevy 305 even though its smaller, its all in the bore stroke combo................

sap

I'd be curious to see how that worked out.

The 302 had a really short stroke though (4" bore x 3" stroke according to wikipedia).

basiccamaro

I've got a Camaro with a 305 that I want to warm over as well. It makes MUCH better sense to run a 350, but this engine runs great, is low mileage and is already in the car. So it's tough to get around all of that.

That said, let me go over the 305 disadvantages.

1. The bore is smaller than EVEN A 283! The 305 displacent comes from the 350- length stroke. So you have to have smaller valves, and you are going to have valve shrouding that hurts airflow around the valve. There is just simply not enough room in the bore for normal high performance valves and flow.
2. The stock 305 (head) combustion chamber size is 58 cc's. And that does not give you all that much of a compression ratio at that. Most of the common Chevy and aftermarket performance heads have 64 cc or even bigger chambers. So trying to put any common high performance head on a 305 will KILL the compression, unless you heavily mill the heads, and thus the intake manifold, which will be cumbersome and expensive. And the valves will still be too close to the bore edges, so close you will need to check for interferance depending on your valve size.
3. There's no replacement for displacement. Not even boost, boosting more displacement would still be better.

So about all you can hope for is about 300- 325 hp on the motor unless you want to spend some BIG money. You could do this with 305 specific aftermarket heads, better cam, headers, intake- etc. etc., all the usual suspects. But somebody doing this to a 350, or heck even a 327 will have you COVERED!
So I understand, I want to use my 305 too. But if I have to do anything that even comes close to pulling the engine out (I prefer to do cam changes that way. It ensures a good re- seal on the timing chain cover/oil pan gaskets, and I can replace the old oil pump and screen and install a pinned sleeve intermediate oil pump shaft at the same time), it just makes better sense to put a 350 back in. Even if you have to go buy a basic GM crate 350. It will be a better base to work with and you will have a new engine to put all of that other stuff on. Just being able to run Vortec heads on a mild build (without modifying the Vortecs) will probably save enough money over aftermarket heads to help offset the crate motor cost. And you might find somebody to sell the 305 to that just needs a decent transportation motor.

I'm still undecided about if I will tweak my 305 or not. In my case I have an old 350 sitting in my garage. And some Vortec heads that I don't want to cut down. So I guess a lot will depend on what it looks like when I pull it part way down and check it's bearings and stuff. It might find itself in a new third generation home.

blp226

here are a couple of articles on hopping up the 305. one thing I have come across is that it may be counterproductive to put a big cam in a 305. it is very possible to get 350hp from one.

http://www.popularhotrodding.com/eng...cks/index.html

http://www.popularhotrodding.com/eng...cks/index.html

blp226

heres the other

http://www.goingfaster.com/spo/343hp305.html

89_RS

That Holley TBI isn't very tuner friendly and the custom chips are generally a rip. Also, go down to 334ci (which are .030" over pistons and 3.75" stroke) because many here don't recommend going to .060" over stock bore. Get a EBL and tune it yourself, a little less radical heads, and a much more aggressive cam and you'll make some good power out of a bored and stroked 305. I'm planning a bored and stroked 305 (334ci) myself and Desktop Dyno 2003 says 427fwhp and 408fwtq. I've attached my list for price and part info.

ericjon262

all you do with forced induction is add displacement, yes, you add compression too, but ssentailly all you are doing is adding cubes,

high rpms? I don't think you'd be able to feed enough air to a 305 to run high rpms, if you really want to increase rpms, shorten the stroke and increase the bore. oversquare motor are known for haveing better high rpm reliablility. the increased bore allows for largers valves, that aren't hugging the cylinder walls, and the short stroke means the piston won't have to traval as far to turn the crank. remember, you have to pick your cam wisely, high rpm motors need more overlap. sounds cool as hell, but not as streetable.

even if you go to the trouble of throwing boost to the motor, do you think it'll be worth it? me, I'd rather have a bad to the bone naturaly aspirated motor.

whats the point of stroking a 305? esp if your going to use a 400 crank. why not a 383 or a 400. A 350 block would prob only cost you a couple hundred bucks more, and have a way better torque curve, also, I have always heard that the small bore of a 305 promotes detonation, I have never had problems with a 350 detonating, bu I have with both of the 305's I have owned. detonation can destroy any motor(except a diesel which run via detonation)

if you can find a 283 (there is one on craigslist here in pensacola for $200) in your area, pull the crank, it's a 3 inch stroke, get the apropriate bearing spacer and drop it in a 350 block... wa-la, a 302 is born.

please, take it from someone who has already tried to make a hot 305, it's not worth the trouble. go for a 4 inch bore, 302, 327, 350, 383 ect. you'll be way more satisfied.

89_RS

FI adds zero displacement to a motor. All FI does is increase the amount of air the engine receives for combustion.

Secondly, 350's don't have a better torque curve than 305's. My friend has a mildly modded 350 and under 2300rpm he has no bottom end. He can take his foot off the break, and the car will barely move forward at idle. My 305 has so much torque at idle, I can take my foot off the break and idle up a 45 degree incline and make it to 10mph before the car shifts and I need to give it gas. Will a 350 make more torque than a 305? Hell yes, any day of the week. But the 305 has more torque under the curve than a 350 and thats why a 305 has a better torque curve than a 350. Just because you have a really high peak torque doesn't mean that you have a better torque curve.

Problems with detonation? Are you kidding? Unless your 305 was drastically out of tune, there should be zero problems with detonation. I've never had a problem with detonation in my 305 in the 6 years I've had it. And that engine is still going strong at almost 200k miles and 20 years plus in age.

Timothayyy

iTrader: (2)

Well Forced Induction is a way of "adding cubes" in the sense that once you reach a certain point, in order to make more power you NEED to either get more cu in or add boost.
Its pretty much the replacement for displacement.

Also saying a 305 has a better torque curve is pretty ignorant..... There are limitless cam/head choices that can shift the torque range around any way youd like. Unless your friend had the exact same cam/heads/intake etc etc then there is NO way that you can compare them.

And you make these claims, but I dont see any dyno charts. I dont care how much your car lurches foward in gear

ericjon262

and what does adding displacemant do?

I'm not saying that it phsically increases the size of the bore and stroke, I'm saying that by forcing air into the motor, you are adding cubic inches to the motors dynamic displacement.

you add FI when you can't add more cubes, or at least thats the way I'd do it, because it costs alot less to make a big inch smallblock than a FI motor esp if you go turbo.

your buddy's mildly modded 350, what kind of mods? if he put big tube headers and single plane intake, on a stock 350 than of corse he'll has less low end torque,

as for the detonation part, I read that somewhere, I had problems with my 1986 K5 blazer's 305 detonating, but it was at about 225000 miles when it left me.

I'm not saying that a 305 is a bad motor, I'm just saying that if your going to spend that kind of money on a stroker crank whats the point.

89_RS

I'm refering to area under the curve. I've done the math enough to know that a curve with a bunch of peaks in it has less area under it than a smooth curve. This is simple Calc I stuff from college, Integrals of Differential equations. We want to know the area under a particular curve going from X2 to X1 in relation to the function of the curve f(x) with respect to dy. I'll post 3 dyno charts. The first one is from a stock 305, the other is from a modded 350, and the last one is what Desktop Dyno 2003 says my mods will net me on my modded 305 (334ci) which should make 427fwhp and 408fwtq. Now if you did those same mods from the 350 on the 305, the 305 would have more torque under the curve than that 350.

I know adding displacement increases airflow, but saying a FI add displacement isn't technically correct.

My friends mildly modded 350 IIRC: 1-5/8" headers with dual exhaust, heads, cam, intake and carb. It wasn't anything wild and he hadn't had time or money to get it all dialed in. I think the intake was single plane. I'm pretty sure he was using a Quadrajet.

I know what you're saying about the 305. But for those of us who are already considering stroking a 305, its kinda insulting when people start acting like we don't have clue as to how much its going to cost us or what our performance returns will be. Some people like to do different things because they find them interesting, not because they are cheap and easy. I guarantee you that if boring and stroking a 305 were cheap, easy, and yielded a really good return on the investment, everyone would do it.

Timothayyy

iTrader: (2)

Desktop dyno isent accurate..... It tends to inflate your numbers. It also does it based on crank horsepower. I dont really care how much power a motor makes, im much more interested in how much actually gets to the wheels. Youre also comparing completely different motors, on different dynos, thats not going to give accurate comparable results. As I said the only way to compare would be everything the same, only difference being 305 vs 350.

If the 305 made such great low end torque...... It would be much more highly regarded. The 305 does tend to make its power a couple hundred rpm lower then a 350. But it makes no difference in the real world and the 350 is better in every way. Also try at least showing dyno numbers in the same range, that 350 makes well over 100tq and horsepower more then the 305. Try adding a cam/heads to a 305, unless you get VERY mild stuff, it will show a curve, it will make more power at certain rpms, and it wont be flat.

ericjon262

I just made two desktop dyno models, one is a 3.735 bore (305) one is a 4 inch bore(350) the 350 outperforms eveywhere, the only variable I changed was the bore.

I tried to attach the files, but It said something about the file being invalid.

a 305 is fine for a dd, but if you want something extra, go with a 4 inch bore. be it a 302 as I described in a earlier post, or a 383, bigger bore bigger valves, more power.

igotta355z28

iTrader: (1)

its all about air flow, biger bore aloys for more air flow!!!!!!!!! the die hard 305ers will never listen . hell if u want the chevy 5.0 badge so bad just build the 302 youll get more power, and respect....

rough

Keep your 305
Get a set of 350 vortec heads, and manifold.
Mill the heads to keep the 58cc/new springs,valves, rollors ect.
Cam
do TBI mods/fuel pressure regulator or get the 454 TBI/FPR
TBI spacer/350 injectors
EBL/tunning
Wal 255lph fuel pump
Rear end, 3.4* - 3.7*
Trans kit
Plugs/wires/dist "MSD please, i used both, my MSD stuff has not broke yet "over a year" I first put accel on, 2 months later i was replacing the dist and wires again. The distributor prongs "the 9 of them on top" where pulling out and the wires, lol, i wont even go there.


With proper tunning, im sure 250-300 hp fairly easy.

A fraction of the price of what you are looking at, and a good amount of power.
_____________________________________

On a side note,

Your 305 + 4 grand good amount of power, high dependability.

350 "1000$" + 4 grand = slightly more power, higher cost budget, dependability not as good as 305

The expression of the 350 driver who just got his *** handed by a 305
PRICELESS.

______________________________________

Be Original, if you want help with your 305 message the 305 guys so these 350 flamers don't diss you every step.
I think people need to learn how to read, he said he didn't want a 350, he don't want a 350, give him 305 advice. Gets really old looking at the 305 posts just to see 350 guys say hey get a 350, LH2R

ericjon262

and you get to freak out the ford guys when you say you have a 302 in in it, because most of them don't know that chevy had a 302 also. I wish that they hadn't stopped building those, but oh well.

Timothayyy

iTrader: (2)

A 350 is just as reliable as a 305..... Their essentially the exact same engine and the same design, just different size bore. You do know that?
Also no 350 will cost you 1,000$. You can get a 350 is good condition for a few hundred and just reuse your 305 parts.

Seems like most of the guys with the 305s just like to dream....... Ive already done all the stuff you guys talk about to my 305 [except the stroker kit and forged stuff, which is a HUGE waste of money] and the 350 is just better, in no way is the 305 better. Just get over it.

ericjon262

how do you figure this better durability, almost all of the parts betweena 305 and a 350 are the same, minus the pistons. and you can make the same power with a 350 with less radical of a cam, less compression ect because you have more to work with.

and if the 305 needs to be rebuilt, a 350 block will cost you next to nothing, I've seen several of them on craiglist for less than $300.

I understand it's cool to do more with less, but a big bore allows for more. if you really want to step outside the norm, don't build a 305, everyone and there gradma has done it, build a 302. you will enjoy it more. I have said this over and over, I'm not saying build a 350, just use a 4" bore, there is more room to go.

89_RS

You know what, I give up. I've tried explaining this in terms that you guys could follow, but it seems I'll have to resort to more primitive forms of communication:

350 is better than 305 cause its bigger and can produce more peak power.

305 is better than a 350 because more of its power is under the curve.

If you guys think I can't understand that a 350 can produce more power because it has better airflow, or that I don't know that Desktop Dyno isn't exactly accurate and rates numbers at the flywheel, you're all dead wrong.

What I have been trying to explain is that if you have more power under the curve, you will have a better motor. I could care less if a 350 produced 600hp at 6500rpm if it had a power curve that has more peaks and valleys than the rocky mtns. I wouldn't want to drive a car with a motor that crappy in it. Now if that 350 produced 600hp at 6500rpm and has really smooth, very nice parabolic power curve to it, then I'd be interested.

And that is why I think the 305 is a better motor than a 350. It doesn't have a power curve that resembles the rocky mtns, it has a really nice and smooth parabolic curve, which means that throughout the rpm band the engine will be producing near max power at all rpms till that curve peaks.

The reason power under the curve matters can be found at the drag strip. You line up two identical cars that both make the same power (regardless of displacement), the one one with more power under the curve will win all the time everyday. Why? Because the car that has more power under the curve has more power available to send to the rear wheels longer than a car that makes all its power at its peak. The car that makes all its power at the peak will only be there for a really short time whereas the car that has all it power under the curve has nearly all its power available nearly all the time.

Timothayyy

iTrader: (2)

All you do is talk theoretical. Try building it. The 350 IS better.
As I said there IS NOT much of a difference between there torque curves. Try examining a 305 and a 350 with the same parts, its the ONLY way you can compare. I bet the 305 will make less power, curves will be almost identical except the 305 will have its power come in a couple hundred rpms less.
The 305 cam from the factory with a mild cam and crappy heads, of course its going to make lots of low end torque..... its common sense.

Dont talk to me like youre trying to explain something to me, im the one trying to explain to you that you have everything completely wrong about the 305.

Jeeze if the 305 had such a great torque curve and this and that. Then why is it garbage? Everyone says its not as good as a 350, and its not. You pull all this crap out your rear end about it being better. What on earth are you smoking?

Mod for mod a 350 WILL beat a 305, that alone proves your thinking is completely wrong. A modded 305 WILL NOT give you a flat power curve like the factory. A larger cam WILL cause peaks to be shown.

89_RS

Your problem is that you are unwilling to think outside the box when it comes to working on a 305. I've seen people with your exact same setup on here making over 500rwhp (thats including your SC). And I've seen people with less than what you have in a 305 make over 400rwhp. I've even read a few guys having made 600rwhp (N/A IIRC) out of a 305. Are these guys the standard to expect when working on a 305? No. But they have proven beyond a shadow of a doubt that the 305 can be made to run with the big dogs.

Just because you can't figure out how to do it, doesn't mean no else can. And for proof, heres a 305 that ran high 11's N/A with 423fwhp and 415fwtq: https://www.thirdgen.org/forums/tbi/...ferrerid=35855

ericjon262

my desktop dyno showed a power improvemnt across the ENTIRE rpm band. not just high not just low the only thing I changed was the size of the cylinder bore. it has nothing to do with airflow, it has to do with displacement, more air more fuel more power period, thats all there is to it. dragstrip times are a whole nother story. if you have a car that launches really well, but has no top end, and a car that dosn't launch as well, but has a killer top end, they can be pretty close. if you want I will email you the desktop dyno files so that you can see them yourself. I like 305's they are a nice little motor for a dd, but if you want to make more power you need bigger valves, and in the 305's small bore big valves get shrouded. thats why I've been saying build a 302, the piston surface area makes up for any torque loss due to the short stroke.

89_RS

I'M NOT DISPUTTING THAT MOD FOR MOD A 350 WILL OUT PERFORM A 305. I'M TRYING TO POINT OUT THAT THE 305 WILL MAKE MORE OF ITS POWER UNDER THE CURVE THAN A 350. A 350 WITH MORE POWER THAN A 305 WILL BEAT THE 305 ANY DAY. BUT IF THE 350 AND 305 HAVE THE SAME POWER AND THE 305 HAS MORE OF ITS POWER UNDER THE CURVE, THE 305 WILL WIN!!!!

AS FOR YOU THINKING THAT THIS IS THEORETICAL, ITS NOT. IT HAS BEEN PROVE TIME AND TIME AGAIN IN THE REAL WORLD. START READING TECH ARTICLES ABOUT THE NEWER LS SERIES ENGINES AND YOU WILL SEE THAT THEY ALL PRODUCE VERY NICE AND SMOOTH PARABOLIC POWER CURVES AND THAT THEY ALL HAVE FAR MORE POWER UNDER THE CURVE THAN THERE PREDECESSORS WHILE NOT HAVING SUBSTANCIALLY INCREASED HP. AND THEY LAY DOWN FASTER TRACK TIMES WITH THESE NEWER LS ENGINES THAN THERE PREDECESSORS DID IN THE EXACT SAME CAR (C6 CORVETTE). ALSO, START READING INTO HOW ACTUAL AUTOCROSS CARS ARE SETUP, YOU'LL SEE THAT THEY SET THE ENGINE UP TO HAVE MORE POWER UNDER THE CURVE.

OPEN YOUR EYES AND BEGIN TO TRY AND SCIENTIFICALLY UNDERSTAND SOMETHING BEFORE SAYING IT WON'T WORK!!!!

ericjon262

not trying to argue, but gen I and gen II to motors don't fit in c-6 vettes, and ls motors are a whole different ballgame, and this is 305V350, ls motors have don't have either.

Timothayyy

iTrader: (2)

Oh yeh, youre a bright one. Comparing a Generation 3 small block to a generation 1. That makes a lot of sense.........

If you want to have more power UNDER the curve, just get a different cam for the 350. Simple as that, you get a cam that makes power off idle, sure itll probably be a mild cam, and you wont make as much peak power but it will be flat. There isent much difference between the 305 and 350 as far as there power curves though, how is that so hard for you to understand?

The 350s are better, there is NO major difference in there torque curves compared to a 305. You open your eyes and just stop making stuff up about the 305 being better then a 350, ITS NOT, as is well established the 350s are better in EVERY way.

And if the 305 was such an awesome displacement, why was is done away with in the newer chevy V8s? hmm I wonder.

rough

Never said the 305 was better tim. and yes a fresh 350 will run you 1k$. Sure you can chum it up and get a yard motor, who knows it could be bored over to much, cracked, sitting for 10 years, who knows.

I wouldnt go cheap on the base of your power plant.

You wont swap heads, exhaust, ecm, injectors, fuel pump, the crap intake manifold, ect onto the 350 thus increasing cost drasticly.
If you live in a emissions state like myself you will have even more to think about when swapping over.

Some of us got the crappy 305 tbi motors and are trying to make the best of it.

89_RS

I understand that bigger displacement will equal more power. I'm not disputing the fact that a 350 will beat a 305. All I have been saying is that if both a 350 and 305 make the same power, then it comes down to which engine has more of its power under the curve. If the 350 has more power under the curve, the 350 will beat the 305. If the 305 has more power under the curve, the 305 will beat the 350. Thats been what I've been saying all along.

Example (will use simple math):

A 305 makes 300rwhp at 5000rpm and a 350 also makes 300rwhp at 5000rpm. Ok, should be a fair race.

Both cars launch at 2000rpm:
The 305 is making 150rwhp at 2000rpm
The 350 is making 140rwhp at 2000rpm
At launch the 305 has the advantage.

At 2500rpm:
The 305 is making 175rwhp at 2500rpm
The 350 is making 175rwhp at 2500rpm
It should be neck and neck, but the 305 still has a small lead.


At 3000rpm:
The 305 is making 200rwhp at 3000rpm
The 350 is making 195rwhp at 3000rpm
Small advantage to the 305 and still a small lead and pulls out a bit


At 3500rpm:
The 305 is making 225rwhp at 3500rpm
The 350 is making 230rwhp at 3500rpm
Small advantage to the 350 and it pulls closer to the 305

At 4000rpm:
The 305 is making 250rwhp at 4000rpm
The 350 is making 250rwhp at 4000rpm
Its neck and neck and the 305 has a small lead


At 4500rpm:
The 305 is making 275rwhp at 4500rpm
The 350 is making 285rwhp at 2500rpm
The 350 is starting to peak and make that final push and pull really close to the 305


At 5000rpm:
The 305 is making 300rwhp at 5000rpm
The 350 is making 300rwhp at 5000rpm
Too close to call, my money is on the 305 though.

Thats why power under the curve is important.

ericjon262

Here in pensacola, I had a cammed running 350, minus a distributor and a carb with a built TH-350 that I couldn't give away for $500. so I ended up having to use it for other projects. it's alot easier to swap to a 350 when it's a carb motor. do they check casting numbers or something? I don't see how you could tell a difference.

Timothayyy

iTrader: (2)

Ive got a crappy 305TBI motor with comp cams camshaft, 113 corvette heads, edelbrock intake, aeromotive/walbro for fueling, EBL ECM, hooker headers and exhaust. LS1 rear end, aluminum driveshaft. Also have a Whipple supercharger that I plan on installing next month.
My parts are MORE then good enough for a 350 when my 305 takes a dump on me, I wouldent bother spending money on rebuilding a 305 or getting forged internals on it.


89_RS, im not even going to bother responding to you anymore. Youre so full of BS, all you can do is pull numbers out your butt, and none of its true.
A 350 making 300whp is considered mild, and a 305 making 300whp is almost extreme. You can use all the math in the world, it doesent mean **** in the real world.
Like ive said...... try building it before you start talking ****. Stop making stuff up, seriously dude. All your doing is misleading people. Go build it, then come talk, with real dyno numbers, not math.

rough

Id rather beef up my 305 and be original, then beef up a 350 and be like everyone else

BTW the fuking 350 board is that way ----------------------->

ericjon262

thats true with any motor, but what I'm saying is that a 305 V a 350 only thing changed between the two motors is the bore, the 350 will have more power under the curve as well as up top, it's simple I don't really know how to explain it any simpler.

Stekman

You all argue like you're married. Or 16 yr old schoolgirls.

ericjon262

sorry to burst you bubble, but it's not that original to mod a 305 I've done it, I know several people around pensacola who have. if you built a 302 that would be original.
----------
I disagree with you, 300 hp out of a 305 isn't extreme, by that reasoning, 350 hp out of a 350 is extreme.

Timothayyy

iTrader: (2)

300hp is rather extreme for a 305...... 200-220whp out of a 305 would be a mild build. Im shooting for around 300hp with cam, heads, intake and supercharger on a 305.
Getting 300hp all motor on a 305 is not easy at all, you need good cam and head choice and a good tune.

400whp on a 350 is about as difficult as 300whp is on a 305.
I think its 1cu in equals about 1hp? Not sure, but 305 vs identical 350 the 350 will make a % more horsepower. So to make up the difference in displacement you need a more aggressive cam, or boost on the 305 to make up the difference.

89_RS

I know. I was trying to point out that the newer generation LS motors had more power under the curve than the older generation LS motors and thats what made them better than the older generation LS motors even thought there was little difference in the peak numbers. I wasn't trying to compare a Gen I SBC to a Gen III LS motor.

Tim, I don't know what I have to say in order to convince you that I understand a 350 is better than a 305.

And yes, I know why GM dropped the 305 and it wasn't because of the displacement. GM used the 305 in light trucks and vans upto the 1995-96 model years. The 305 proved to be very good in that application. Problem was that it cost more to make a 305 than it did a 350 due to different bore sizes. GM needed to stream line its powertrain development to reduce cost. The 305 got the ax because they could destroke a 350 far cheaper than they could cast and ship a 305 block. That, coupled with GM's push for a modular engine design, which resulted in the LS engines, was the final nail in the 305's coffin.

In the end the 305 went away because of product cost rather than lack of displacement.

rough

[quote=ericjon262;3990182]sorry to burst you bubble, but it's not that original to mod a 305 I've done it, I know several people around pensacola who have. if you built a 302 that would be original.
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TO me its more original then a 350. First question i get asked about my car, it got a 350 ? Nope a 305, then they chuckle.
Be lovely to make them choke on that chuckle and i know its possible.

Never thought of the 302 idea, that is really original.

89_RS

I understand.

And Tim, even if I built it, got it to do what Desktop Dyno says it can do, you'd still think I'm full of it. If you read Fast355's thread on his 312TBI car running 11.8 @ 119 with 423fwhp & 415fwtq, you'd see that there is a general preconception on this forum that the 305 can't be made into a high hp car.

Stekman

Get over the whole proving a point thing. Run a search, believe it or not, you're not the first to raise this argument, and it's the same old tiresome argument each time. The point of the matter is, per dollar put into it, versus amount of power yielded, the 350 is the superior choice. Always. I've built plenty of each to know.

There is no perception about a 305 not being able to make power. There's a fact that it's both cheaper and easier in a 350.

89_RS

I wasn't debating the price/performance yield of modding a 305 vs a 350. I fully understand that $50/hp gained out of a 305 can be achieved for $13/hp out of a 350. And the 350 can make more power easier. All I was debating was power under the curve.

rough

how do you get 50/hp vs 13$/hp ?

89_RS

IIRC, that was what one of the forum members calculated when comparing mods on a 350 vs. a 305. If you spend $12000 on both engines, the 305 will cost $50/hp gained vs $13/hp gained out of the mods on the 350.

rough

damn man if i had 12 grand to spend on a motor.. *drools* Be one fast TBI, and but im still missing how this is possible. Ill look for that.

Still displacement is not the biggest matter.
I could put 12g's into my GSX's 2.0 4g63 and make more power then a 350.

Wouldnt the smaller bore of the 5.0 be better for FI "forced induction" compared to a bigger bore of the 5.7 ?

Smaller area = more psi sqaure inch with less work from the turbo's/supercharger

blp226

I agree with you that the 350 is a lot easier (and cheaper) to get power from and I love the idea about making a 302 screamer, BUT, building another 350 or 383 is kinda dull, it's been done to death! I'm saying this with a 383 stroker in the engine bay of my Z/28. I like any idea that tries something different. The 302 idea sounds brilliant, but getting a 305 to put down REAL power is an interesting and very challenging idea. Some people just wanna try something different. If we're gonna post on this thread then let's be constructive, and suportive. he has already stated that he's gonna do a 305, he doesn't wanna do a 350, so let's all give whatever advise we can towards helping him build a 305.

You have inspired me to look into building a 302 for myself. I'm gonna do some research on that.

rough

Wonder why i haven't ran into this 302 idea yet. Wonder what kinda numbers it lays down.

ericjon262

I always heard that a smaller bore would have better gas acceleration out of the exhaust ports, good for a turbo motor, but a larger bore would have more gas to force out (assuming same stroke.), also good for a turbo motor. the main reasoning I see for a small bore on a FI motor is wall thickness, thicker walls don't distort as bad. the downside is that there is less piston surface area, which means you have to run higher cylinder pressures to make the same power which is harder on the engines interenals.
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It really depends on how it's built, the nice thing is the big bore allows for big valves, and the short stroke means the piston won't have to go as far for a full rotation... can you say high rpm screamer?

-Eric