Sometime in the (hopefully not-to-distant) future i want to go for the quickest/fastest LO3 3rd gen out there. By LO3 i mean LO3 aka bolt-on only...stock heads, stock cam. One question though; is an intake manifold considered a "bolt-on"? So anywho what kinda times are you all turning with an LO3 engine? and what kinda mods did you have? race weight?

why would you want to limit yourself with those crap heads and not much better cam?

because its the thrill of being challenged to go fast in the biggest pos v8 GM ever made

You're calling my motor a POS? I find that offensive. Figure out how do it on your own then. With a lame attitude you won't get any help, Rooks.

hmmmm, well, i will go faster than you with less money with my better heads, bigger cam and a carb.

plain and simple, faster wins races.

which is why my next motor will be a 4"+ bore motor.

Mine is not a P.O.S.

Heads and intake manifold are generally considered bolt-ons.

I'm trying to do the same thing for pretty much the same reason, and yes an intake manifold is considered a bolt on. Mine is geared for nitrous use though. Good luck on trying to beat me

I definitely don't consider heads a bolt on

but what about without the nitrous? or what if i use the same nitrous on my car? there are a ton of things you can do to make it go fast, but with a better set of heads, it will go faster. even if you port/polish your heads, well, that's really not a bolt on mod.

my 416's are bonestock....fresh valves, but stock size. 13.75@100mph. still has more in it. i think with this combo and more tuning i could reach mid/low 13's pretty easily.

i posted a best of 14.791 @ 91.11 MPH w/ 2.068 60' in the quarter with the mods in my sig minus the edelbrock intake manifold, probuilt tranny, and 2400 stall torque converter. The times were on a set of 215/65/15 goodyear GTII tires, so im hoping that the new 245/50/16 Kumho tires and iroc rims will help traction alittle, if not ill have to get a hold of some drag radials. This was all on stock heads, camshaft, intake, and 1 11/16 bore tbi

That's great that you run that, but it's not relevant. Too many opinions in this thread. It's cool to build up a bolt on LO3 and see what you can run. When you reach the limits then you can run a real motor, but at least you found out its limits and maybe showed some good times. I'm going to see what my tuned up bolt-on LO3 runs next spring.

Maybe I can join you guys in the race, but I won't be running nitrous so you got me there. Also, anyone that thinks their LO3 is not a POS from a performance viewpoint is crazy because it is. I drive one, they aren't fast. Next spring comes the LO3 bolt-on timeslip battle

edit: I posted this at the same time as Vjo it doesn't refer to his post at all. Those times are just impressive man, you should be able to knock down some great times next season.

well, i just think your wasting your time with those heads when you can find a set of 416's for less than $50 for the PAIR.(make sure you get them checked mind you) a little grinding action on the two middle bolt holes on the intake, and presto! much better flowing heads for not that much money.

one thing you guys got going for you though is better cold starting characteristics and and probably better city fuel mileage (i get 7-10 city/ 22+ highway).

this was not ment to start a flame war or anything, i just think that money is better spent on a better set of heads. heck, i like the 305, that's why i got one in my car still, but when i want to go really fast, i will be putting my 4" bore motor in (haven't started building it yet, so i don't know what crank i am going with, but the block is sitting on the stand in the shop right now.)

Well, see the best way to make easy cheap power is with a 4+" bore motor. So, building a bolt-on LO3 is not expensive and you doln't have to spend money on heads. Everything that you bolt on to this 305 can be moved over to a bigger inch motor later on. Get the exhaust, suspension, and intake to support a motor in the future too and see how the LO3 runs for now. That's what I'm doing.

alright, have fun

Ofcourse there are better motors, heads, etc out there. That's not the point. I started my goal years ago when I was told I could never be fast. I want to make them eat their words. I think it's fairly impressive what some have done to this motor and when I achieve my goals I can guarantee you I will be proud of my accomplishment, if it means anything to others or not.

First off i apologize for the pos comment...how bout least performance oriented v8 ever made my gm. fair?

yea my main idea is to take the stock 305 tbi powered 3rd gen and get it to go as quick as posible...i want to see what i can do with a 305 tbi top-to-bottom motor...so im assuming so far the time to beat is a 14.7 at 91

my plans so far are going to be aluminum ds, nasty gears, complete aftmkt stock-style suspension, go super weight nazi, 6 cylinder powerglide, header-back exhaust, fiberglass cowl hood w/ k&n complete substack intake setup for carb/tbi, edelbrock intake manifold, holley 670 cfm tbi, custom tuning, underdrive pulleys, 160* t-stat, no emissions equipment....any comments?

are you planning to just make this thing a strip-only car??? You might want to just stick with the Th700r4 tranny or go with a th350.

that powerglide is going to hurt more than help.

Spoken like a true Hot-Rodder!

Don't ever expect to see 11's, or even 12's for that matter. Now, if you focus you're attention on you're naturally aspirated 305 TBI's heads, cam, intake, exhaust.... as well as GEARING (rear AND tranny), SUSPENSION and WEIGHT (weight meaning close to, or even under 3000 lbs), I think you'll be in for a very big shocker.

Trust me!

with ridiculous gearing, your going to have a hard time having a streetable car.

You're absolutely right. But if the focus is being kept on the gearing inside the tranny (along with the right stall, if it's an automatic), while keeping the rear cogs below 3.55... it should still be very streetable.

Some have seen 14.5 with the stock heads and cam. You are going to need chip work. You can do every bolt on under the sun but the heart and soul of these motors lies in the chip. If you do not burn your own, you will remain slow.

ok, given a 3.55 gear or lower (possible even a 3.73...i just like those gears ) and make sure you use no taller than a 26" tire (275/50/15 bfg drag radials would work really well...26.1x9").than a 700r4 built right with a good shift kit (something like the transgo would be GREAT) and no more than a 2800-3000 stall converter and the car would be really streetable with the ability to REALLY get the power down to the ground. just hit the suspension up and you'll be set.

reason i say 700r4 is the first gear, especially if you want to stay with a >3.55 gear. <3.73 gear and a th350 would be great. but streetability will be hurt.

I too think the powerglide is wrong for that car no matter what stall and gears you have. A powerglide works well with an engine that has a high powerband like built race preps and newer LS1s, anything that can rev. The powerglide 1st to 2nd gear isn't enough to have both a good torque multiplication launch AND trap at peak horsepower. The TH350 would be the best hands down.
I always like hearing of guys with unusual goals. Hitting 13's is like "bah, $350 for a nitrous kit and I'm there."
Here's my next question, is porting considered a bolt-on? Those heads are a killer and that cam is exually worthless, both of those things are your bottle necks. No matter how much airflow efficiency you bolt onto this motor you're not going to make a bit of difference. So here's the deal, find the horsepower curve and gear the car accordingly. The fastest car is the car that makes the most average horsepower. If you could have a CVT trans and neglected any friction/inertial losses, you would accelerate the fastest at by keeping the engine speed where it made peak horsepower.
Since we don't have a lot of CVT options (zero) we'll need as many gears as you can fit. So technically, if you COULD shift fast enough I'd say get a T56 and install like 8:1 gears in the rear .
Also keep in mind that with your power level and still heafty (3000lbs) you'll probably benifit by going with a more efficient drivetrain. This means a manual trans. Any car that's in the 13 and 14's will benifit more by having a more efficient power transmission than more launching torque. Never have I seen a 13 second car go faster with an auto trans no matter WHAT the stall and 60' compared to a manual transmission. If you could get a T5 setup that would be ideal. Might need a rebuild but you'll get more power to the ground and the shifting time will more than offset the efficiency.
You could get a powerglide with a high efficency tc but the only thing you'll have going for you is the weight reduction (again, 13 second cars respond better to 5% drivetrain efficiency than 1% weight reduction).
If you're still not convinced on the manual trans then look at the Fox body guys. Most of them don't change to an auto until they're in the low 11's and even then the results have been mixed. Fastest guys are the T5's and TKO's .
For the intake, a torque 2 would be good, or any Holley single plane that is low profile. Depending on your hood clearance, get the most plenum volume possible. Something like a 1" carb open spacer would work well. Some 350 injectors, long tube headers!!! True dual 2.25 or 2.5 exhaust with a balance pipe. Trust me, that is the exhaust to use to get the most horsepower out of a standard crank v8. Oh, and don't bother with primary sizes. 1 5/8 would be fine but 1 3/4 would be ideal. I'm sure I'll get guys tell me and you that you won't make as much "low end"... don't listen to it.
Here's my low end torque monster theory... it's just a way for people to feel better about an engine that can't make any horsepower. Now if you're set on using a powerglide and aren't going to be using a 4000+ stall converter then they might have an arguement but even still, with a high stall converter that whole "low end torque" is just wish wash .

Leave the powerglide in the 60's! I think they should be called slip'n'slides unless you want to dump some big money into them. I'm a fan of running the biges exhaust you can past the headers and using the primary header tubes for tunning, 1 5/8 would be fine for a lo3. 1.6 rockers to try and give the sorry cam some lift. I would go nuts on the heads port all you want, they flow so bad I don't think you could make them worse.A good single plain intake. I too think a T-5 would work the best. dump all extra weight insualtion under the hood seats interor plastic in the wheel wells take off the front sway bar and find some blown out six cylinder struts for the front. Not good for driving but good for the track. oh and ajust the drums for zero drag befor you run. I sure there are alot of other tricks out there too.

ok i like your reasoning prevost(2fastforyou?) and when i get around to this project i'll look for a t-5

look up 90RS305... he has a STOCK LO3, only mods is a flowmaster 40 series and he ran 15.3... LO3/T5 and a lead foot... probably beats my LO5/700R4 combo...

Powerglide is a bad idea.....iirc 305's usually had bad gearing to piss-poor gearing....that would need changed, and a more agressive cam would be in order. Stroker kit perhaps?

I think all the TBI cars came with pretty tall gearing. Not that a stock L03 really needs steep gears, but something a little steeper wouldn't hurt. Your gear selection has to be matched to your powerband (mainly your cam). Going with 3.73s, or 4.10s on a stock L03 will just make you slower than stock.

As far as the stroker kit for a 305, its been thoroughly discussed in old posts. It is generally considered to be a total waste of money.

Cam is a good idea, just keep it mild.

Also, do yourself a favor and throw those heads in the trash. Pick up a set of 416s, or a set of 081s. They are 10x better than the stupid swirl port heads you have now.

Sorry, I just noticed you want to keep the stock heads and cam.

I don't think you know what you are doing to yourself, and I sure hope you don't throw 2 grand at your car trying to make the car faster. Whats going to happen is that you'll be pretty damn dissappointed.

I read a post about two years back where someone bought a blower kit made for the L03 specifically. Stock heads, stock cam, stock everything. Want to know how much they picked up? I think it was about 30 hp. So they spent like 3 or 4 grand to get up to 200 flywheel hp. Want to know something....that blower is no longer sold. It was a waste for someone to just slap it on a completely stock engine, especially with L03 heads and cam.

???
That isnt true at all, just look at my sig.

I agree with vjo, and no matter what people say it's been proven time and time again. If you actually do some math you'll figure out why, but I'm not going to explain it AGAIN.

Yeah, the math is there, it's basic calc2 integral stuff. You'll here people talk about "area under the curve", yeah, it's an integral . The simplest way is to just gear the car to cross the 1/4 mark in whichever gear is 1:1 (usually 3rd in autos, 4th in manuals) at the engines redline. This corresponds 99% of the time with the advanced math.
More of a reason to get my website finished and up and running. I've got a page of explaining how to gear a race car.

I've seen quite a few stock L03s slow down after a steep gear swap. Mine was one of them.

I had stock heads, cam, intake, T56 transmission, and factory 2.73 gears.

I had 3.73s installed to better mate with the tranny and the upcoming engine swap. Car felt 10x better on the street, and especially right off the line, but it was actually slower than with the 2.73s though. Quite a bit slower.

If I remember correctly KingTal0n also tried 3.73s on a stock L03 auto when he first got the car, and he slowed down as well. I've seen quite a few similar posts.

Matching your gearing to your powerband isn't BS. Look in a parts catalog, and you'll often find in the cams section how they give you a nice little chart with cam categories and corresponding gear ratios to go with the cam specs.

JPrevost, I'm curious as to the math for calculating the ideal gear ratio. Can you post a link? I'll see what I can dig up right now, should be able to find something.

92blue, I'm having a hard time figureing out what exactly you have in your car. From the sounds of it your stuff is stock, but according to your profile you have an RS with a 350tpi and a BW 6 speed?

Bruce (90RS305)

Right now I have a 350 TPI and 6 speed. I did the tranny, then the rear end, then the engine in that order. So for a while, I had the stock 305 with the 6 speed, and 2.73s. Then I went to 3.73s with the 305. Thats what I was referring to.

its not a performance motor by any means.


so if you look at it from a purly performance perspective... its ****ty.


but its not all bad... it is still the same size bearings, it still has the excelent SBC oiling system..


my friend overheated his motor... blew the remaining coolent into the oilpan, blew both headgaskets, and (in a roadside attempt to "fix" it ) overfilled the oil by adding 3 quarts.


he drove it 65 miles back to his house.

its still running... it makes milkshake oil when you fill the coolent and start it... its full of crap from never changed pensoil oil.... but its still, SOMEHOW, running.

so its not all bad.





but from a performance perspective, it sucks.
the TBI sucks.
the intake sucks
the heads suck
the tiny bore sucks
the exhaust manifolds suck
the exhaust y pipe sucks
the fuel pump is too small (therefore it sucks)
the tinyest production cams put in SBCs are in there. and that sucks.
the timing maps in the ECM, suck.
the fact that if you cant fuel as much power as much of you want/claim to have.... sucks.

overall, i think that adds up to a sucky motor that needs to be replaced to have meaningful performance... sure you can pick your fav part to keep.. if its the 305 block or the heads or whatever...but fact is, take ANY one stock part from that motor, put it with a actual performance motor, and i can tell you what sucky part is holding that performance motor back.





anyone who feels the need to dispute this responce, promptly needs to do so basic research of how the motor works.... because the only intelligent reply is, "i concur"

i concur

The water pump and pistons aren't half bad .

my stock alternator works pretty well too... and them centerbolt valvecovers... same ones come on the 350!!! lol... Even swapping my 305 out for the same crappiness in a 350 made a difference like night and day... im running an LO5, in essence, an LO3 305cid with a larger bore... same stupid swirl design heads, same peanut cam, stock exhaust manifolds, stock exhaust Y pipe (or it more closely resembles a T on my car...) stock intake manifold, stock TBI (larger injectors of course), and it still made a crazy difference. But i know if i were to get some 081 cast heads, an LT1 (or bigger) cam and some headers/Ypipe... it would make almost the same difference... Bill (Azvolfan) has a 305 with 416's, new intake manifold, headers/y pipe and an LT1 cam and im sure he is running the same hp/tq numbers i am... and i have 45 more cubes... the moral of the story... Stock TBI ANYTHING, sucks...

oh, and I concur..

I dunno, I'm kinda fond of my 454

ok, SBC TBI sucks... lol... damn, you gotta be cool with your damn 454...

Its not TBI thats the problem with the L05 and L03. Its the heads and cam. Have you seen the specs of a TBI cam?!?!?!

What the hell were they thinking....

I've never seen smaller cam specs...

Its rumored that when the light hits a certain angle, you can almost see the cam lobes.

this is more on the subject of fast stock LO3's and less on TBI bagging, but... I raced 90RS305 down the freeway offramp last night and i got SPANKED... he is running LESS modifications than i am, and i have 45 more cubes.... Thank you swirl ports... peanut cam and swirl ports turn a 350cid SBC into a rather large and loud paperweight... you might be faster bruce, but i sound meaner lol