i know that alotta people say just junk the 305 and go with the 350....but im here to say a little different. It all depends on what ya wanna do. You can build a 305 relativly cheap that will run with an LT-1 or LS-1 easy and still get good gas mileage. Ive found a great link that ill list at the end of this page so everyone can check it out sometime. 305's have a higher redline than a 350 thus giving you more motor to work with. If you can get your 305 to breathe and exhale right (which they are terrible at doing stock) you can find a monster under your hood!! Anyways....just check out this website to find out what I mean..... good luck!!!! This guys (SR-71 Blackbird) is sure to be a showstopper!!www.newcovenant.com/firebird/engine.htm

Ps. prepare 4 alota reading but its just like a good novel and u can learn alot.

 

wrong wrong wrong wrong wrong wrong wrong...


The ONLY difference between a 305 and 350 is the bore size. 3.736 vs 4.00

The stroke and rod ratio are the same (3.48 stroke, 5.7 rod length = 1.64 rod ratio)

Therefore a 305 WILL NOT rev higher than a 350.

Again The ONLY difference between a 305 and 350 is the bore size. 3.736 vs 4.00

You can overbore the cylinders .090, and the 305 's would still be smaller (3.826)

Spend the same amount of money and the 350 will make more power. That's why people do it.

 

ya I just read that. That guy doesn't know what the hell he is talking about. Small bore long stroke engines are low reving torque truck engines. That's why there even is a 305. They put it in millions and millions of trucks.

 

Is this guy serious, he says u will gain like over 50 horsepower from just portin the heads, and make over 400 HP and still have a somewhat streetable 305. If it was that easy, wouldnt everyone do it?

 

well on the heads its doable. Pablo ported some l69 or lg4 heads and ended up at around 260 HP with a single plane intake, 454 TBI, and a cam.

 

260HP yes. 400HP? ...Only with money. I know someone with a real dyno tested 380HP 305. Its a carburated, cackling solid roller engine with $3000 heads. Its used exclusively for road racing.

Real-world 305 engines with half-way streetable manners are restricted to 300 to 320 HP, and then, only with lots of research & money. Us folks on a budget will be hard pressed to hit 300 horses. Probably 285 HP is about all the 305's grasp in the practical world, IMHO.

==Dan

 

the difference in bore is exactly waht makes it so it can breath at higher revs. it does nto actually make it rev higher, just allows for soem different physics(tiem for another air velocity lesson kids)
with a 305 you are looking at a narrower combustion area, this mneans that any spent gasses are already better positioned to be sent out through the exhaust port. with a wider bore going throught eh same sized valve you are asking the spent gasses to compress into a narrower area and then squeeze past the valve instead of just havign to get past the valve.
this is the exact reason that so many of the great turbo motors have a larger stroek than bore. since the gasses are positioned better already they maintain velocity with a lot less turbulance.
the problem boils down to, can you get a 305 to run reasonably on a cam that can take advantage of this? usually not, as it requires teh exhaust lobe to be much larger than the intake lobe and it must havfe a sharper ramp to prevent too much overlap. this means a cam that can have less idle vacuum than most people care to live with.

later
tim

 

Sorry NJ, I'm not buying it. You are using intuition to solve the mystery of airflow, not science.

What you need to study is the concept of valve shrouding. You can more effectively utilize a valve if its moved away from the cylinder wall. The 305 moves the cylinder wall closer to the valve relative to a 350 with the same sized valve.

If you want to build yourself a killer turbo motor, get a really big bore and put in a small stroke. You can then put in a bigger exhaust valve and work the exhaust port. I always thought that a 4.125 inch bore with 3 inch stroke would make a good turbo motor.

 

are we talking abotu at the crank or at the wheels where it counts? i was mathematically pushiing around 220-225 to the wheels from the stock cam, that is about 275-280 at the crank. my combo was not terribly pricey either, edelbrock heads($1100), edelbrock intake($215), ultimate tbi mods($10), aluminum tb spacer($50), 350 injectors($20 from salvage yard), 1.6 roller tipped rockers($190). i had a stock chip in the car and a stock pressure regulator too. so for under 1600 in mods i have as much power ads many of you are saying eht limits of a 305 are.
with the addition of the cam, a bigger tb, swapping to a hlley intake(roughly the same price) and a custom chip i expect to see 300 at the wheels(abotu 375 at crank) adn i have still spent under $2500. the 305 can go much much further if i took time to do more development. a rebuild woudl be nice, my motor has 107k on it, raise the compression up over10:1 and i coudl see another 20-25 at teh crank, swap in an LT4 cam instead of the LT1 cam and there is prolly another 15-20. does aroudn 420 at teh crank sound liek a lot fo $3000-3500 crate motors to you guys too? it sure does to me.
i have a block, if i can find a willing and funded victim errr, ummm subject, i woudl be willing to try to put this all in practice next winter when my motor coems out of my car. i say for under well $3000 you can have a perfectly tame idle, drive anywhere motor, that will put 335+ to the wheels(420ish at crank) with a TBI on top. that is a complete motor for the price of a good performance long block.

later
tim

 

I think we pulled 260 out of our butt by comparing his ET to similarly sized a type of vehicles. I don't remember exactly.

 

But isn't the conversion from 1/4 mile distance to HP more accurate when using trap speed than ET?

I mean applying HP to the rear wheels is important, but if I have a 400 HP 350, and someone else has a 170 BHP stock SAE (aka 226 gross flywheel HP), I could run a 18 second ET due to ****ty traction but cross the lights at ~100 MPH. The stock 305 could run a 16.5 ET (just using round figures so no flames!!!) at ~85 MPH and I would still be making more HP, just not getting it to the ground, right?

So NJ, if you're gonna use 1/4 mile distance to calculate your HP, then you should use the trap speed, not your ET, right? Oh, and your weight because I know you've shed a few lbs. lately.

AJ

BTW :lala: *** :lala:

Now I'm dancing around my '***' HEHE. :sillylol:

Or...
***


My thumb up ma '***'

Ok. I'll stop now.

 

You may call me a skeptic, but until you actually put it on a dyno, its just bench racing.

 

If only you lived in Cali, I would take you up on it right now!!!
Iplan on using an LT4 cam with some afr heads exhaling through
two cats.

 

i did use my trap speed. mph is a mathematical function of your pwoer to weight ratio, et is just whether or not you hook and what gears you have.

later
tim

 

why does everybody ride the AFR heads? they are such a rip off. for $300 less you can get a set of TFS heads tah actually flow better. the edelbrocks only flow a little less and they cost $400 less, and are great for a 305(i think i proved that)
i am nopt saying that AFR doesn't make a good product, they make a very good product. it's just he price that i question.

later
tim

 

I'd love to see someone build a massive 305...but almost no one does it. I was on that road, but like a loser...I gave up. Sorry.

 

i was on the TPI board one day and they had a video of a guy running a 305 TPI and he was running 9s...he either had a vortech supercharger or a turbo i cant remember which

 

I'd say there's no reason why a 305 with forced induction couldn't make 9's, assuming tthat you spend the thousands of dollars needed: The engine uses the same size crankshaft and rod bearing journals as a 350, and even has the same stroke. So you could very well buy some oliver rods and a steel crank, and build yourself a super bullet resistant 305. Just splay the mains, fill the block with Hardblock, and have some custom pistons machined up.

However, the cost will be nigh-identical to a motor with 45 more cubic inches, and the bigger bore motor *will* have a bigger exhaust valve and more exhaust flow potential.

 

Flowrate is your only concern? Boy am I glad you arent working on my cylinder heads.

 

Well, us diehard thirdgenners know how to strike a balance between performance and style...

Actually, this is my very last post to this thread. I am glad that some of you guys have such a loyalty to the GM305 engine. However, I would like to politely suggest that "school spirit" is best left to supporting the team and not a specific team player. The GM305, while a great and reliable engine, is not the star performance motor in the GM lineup. Physics and fluid dynamics dictate that it is not the most optimized configuration of the smallblock lineup. Other smallblocks weigh the same, and offer more performance potential for less cost. What the GM305 does best is this: Mid-level performance with modest fuel consumption. As long as you retain focus on "Mid-level" performance and "Modest" fuel consumption, you will find the 305 to be a great little performer. If, however, you have illusions of grandeur and try to build a stellar monster motor from your 305, you will be deeply disappointed when another GM motor, of much less cost and better road manners, hands you your hat as it walks past you.

Its like this:

A rippin' cacklin' cam stutterin' 305 equals one muscular 350 equals one tourquey 383 equals one smooth idling 406. That, my friends, is the *real* world.

 

wow....didnt think id get this much of a response!! I'm not downing any other motors or setups...alls im sayin is that the 305 can be a contender and also be a daily driver too. Im not wealthy by no means, so i cant go out and get the big crate engines and beef em up like some can. I gotta make due with what i got and i know that my 305 is the best runnin engine ive ever had....even with as much hell as ive put it through!! In my younger day of owning my camaro i ran it extremly hot several times and not some much as a tiny loss of power or a hint of smoke or oil burningl. Im just gonna stick with whats been good to me and make the best off it. Besides new tranny, paint, 4thgen leather seats and everything else takes my money too. Thanks alot guys and gals!!


ps im in it for the long run.....this car goes down to my kid. *** willin

 

im guessing you love your car like i do...take my advice and dont give your kid a fast car for at LEAST a year of driving something really slow...i know if the camaro would have been my first car i wouldnt be alive today. i cant believe i walked away after hitting a guard rail at 100mph in a 1994 hyundai excel GL. its a miracle:hail: in my eyes either that or im one tough ****. ill admit im still a nut in the camaro but i know my limits and i dont drive like i used to even tho i had a slow 4 banger...i used to hit 100 in that car is 25 zones and stupid **** like that. give the kid some time to get used to how to react and everything...i feel that if i were in the hyundai and came to the same situation now that i wouldnt have wrecked but i paniced when it happened and totalled the car beyond repair but somehow walked away...it was nutz:hail:


:::edit:::: been reading the post some more and i know a 350 makes alot more power but most of the guys on the board (like me) dont want a full blow 10 second car or anything like that. im shooting for a high 13 NA motor which is possible for less than the cost of a nice crate 350 your gonna have to have suspension mods anyways either way you go

 

you can make a 305 go just as fast as any 350 or 383 it just takes a lot of work. im in the middle of a 305 build up now and i made up a 305 combo that robertg put on his desk top dyno and it made 340 hp and 336 ft lbs torque. that should be good for low 13's high 12's with good traction. if you dont believe that ill send you the dyno chart

 

yeah, the 305 is a pretty bulletproof engine. I just like it because you can retain economy and still have something that can surprise alot of people. I myself aint into so much driving it super fast, i just like knowing that its there when i want it. Besides, it dosent matter if ya got a 350 with 500 horsepower; if ya cant get it too the ground effectively....yer outta there!! ex..... i hadda 91 grand am with the HO quad4 and the 5 speed....it would hang with most any v8...maybe not beat it, but it wouldnt get smoked either and thats sayin alot. Besides my camaro is gonna be about the WHOLE CAR not just the motor....dont want the fastest....just the cleanest!! But i guess with a tag that says V8POWR...i gotta be ready to at least be a contender and thats what its gonna be.... a TOTAL CAR CONTENDER. Even if i get beat in a race....im gonna look good crossing the finish line!!

 

DD is a good power estimate, butit makes up teh power at the crank. 340hp is only about 272 at the wheels. that is well into the 13's, prolly aroudn 13.5's or .4's, but i think 12's is really pushing it unl;ess the car is very light or very geared.
don't get me wrong, that is a very strong number for a 305, but you are gonna nned more to go for 12's.

later
tim

 

I don't think I have to say anything except maybe...well put.

 

Are you willing to back that statement up?

 

i did use science and intuition to solve the 350 air flow issue. i looked into how the air moves aroudn a valve and sort of figured how much space it needs(i am not a trained engineer) adn then i measured everything and figured out how far apart everything woudl be. that is how i came up with the ideas about cam sizes to use to develop velocity, since the shrouding itself prevents a total air flow theory to be used and still maintain good drivability.

later
tim

 

If you're so happy with your 4th gen then why are you still hanging around the 3rd gen boards? You know they have places for guys with 4th gens dont you?

 

what about ported aluminum L98 heads from a corvette?

 

I've got a set of ported aluminum L98 heads on my formerly TBI 305.

 

I finally road in a car that was BUILT...it was a 87 firebird with a 350 running 13:1 compression running off jet fuel he said...anyways he has tubs in the back, 10 point cage, beastly fuel pump and cell, just runs open headers and 26 inch slicks...damn thing pulled the front wheels up at least 3 feet with me and him in it and on a public road :hail: :hail: :hail: :hail: :hail: i was about to **** myself right there was not and i repeat NOT streetable tho...cam was so huge it barely idled not to mention it gets .5 to a gallon off 5$ a gallon jet fuel but it was completely crazy and i dont see a 305 doing that...well actually he has a sand drag car with a 305 that is pretty freakin fast runs a 11 in the quater on dirt so who knows maybe the potential is there somewhere

 

what do L98 heads do for the compression? Are they worth it?? I also read that if you port and polish the original heads and maybe put a bigger exhaust valve in it will do really good. Any info??

 

400 HP is "possible" but it would have to be carbed, aftermarket TBI, TPI or Accel DFI. It wouldn't be very streetable, the bore is too small to shove that much air in and be streetable. Now a supercharged 305 with 400 HP and DFI would be Very Streetable. Is there anyone who has done this?

 

Let me know when u get all of your tuning issues straightened out. I refuse to get those 305 world heads and am deciding between the corvette heads and some arf 190's.

 

unlocked after flame cleanup.

 

L98 heads keep your combustion chamber at 58cc's and flow much better than L03 heads, (like what doesn't )

 

I heard that porting these heads could
hurt low end torque.
If so could you counter this
by further milling of the heads?

 

torque? what torque? 255TQ? comeon now. Those heads wouldmake an L03 night and day better.

 

hope so