just wanted to know if I did almost everything possible to my 305 LG4 besides nos or supercharger, could I possibly get 400 hp, or close to 400 hp?

 

its possible, but your going to be spending a FORTUNE to pull it off, best of everything parts wise going 350 you could get the 400 mark ALOT easyer and alot cheaper.

 

You can get there for about $4000.
325hp is easier on the wallet, about $1700.
Needs cam, intake, headers, exhaust, heads, carb, and that's about it.
This motor in the article was an LG4 155hp V8 from an 82 Camaro.
My 86 LG4 Trans Am motor is now almost an LB9. I expect the peak HP of mine to be right at or under 300hp.

 

ok well....im getting hedman headers with their y-pipe, then im either goign to gut my cat or put a striahgt pipe through the cat, then the hooker cat-back, as fo rthe engine, im getting a comp cam 262h grind, edelbrock 7107 rpm manifold, crane aluminum energizer 1.6 ratio roller rockers, and new rods and springs. How much hp do you think I would have then? And after I tweak my carb becasue Im, not sure if Im getting a new one, if I would itwould be a remanufactured edelbrock. What do you think?

 

Id say you would be right around 250 horsepower or so, maybe 270.

I did basically the same stuff to my 89, xcept my cam has a little bit less lift, the engine is a 350, and the manifold is not the rpm, just the performer, and it is pretty quick, I think its around 300hp, I can beat the TPI cars with it, and mine is carbuerated.

If I were you, I wouldnt put the 1.6 rollers on, just the 1.5s, that cam is already pretty large duration wise on the 305, and the 1.6s will just make it even more so. Also, if you have a stock hood, the Perfomer RPM will not fit under the hood, at least with an air cleaner on it, I know, I tried it.
Just go with the Perfomer manifold, its still tons better than the stock qjet. It also mathes the rpm range of your cam and engine.
Wouldnt you rather make power from idle to 5500rpm(the max I would run a stock motor) than from 1500-6500? The rpm is just wasted rpm.
I would rather have a slightly less powerful motor that is perfectly mathced to the rest of the car(gearing, rpm range, weight) than a motor that makes more power wear you dont need it.

 

If you want good off the line performance I'd change that lazy gearing.

 

one word,,, nitrous, second word blower

 

The Performer RPM intake will fit under the hood, but requires
a drop base air cleaner like the '65, '72 Z28, Corvette assembly.
Mad MAX: Thanks for the info on Edelbrock QC. If I go to buy an Edelbrock product, new in the future I'll be sure to inspect it carfully in the store, before buying it.

 

I guess that would depend on your definition of "everything possible"...

The heads that are on it will certainly not support that kind of flow. Some other heads will be required, with far larger ports. It will have to turn up to some major RPMs to get to that power level; I would seriously doubt that it's possible to reach the required RPMs with anything but a solid roller cam. 305 rods won't stand up to that, nor will a 442 casting crank, nor stock cast pistons; so it would require an all-forged bottom end.

So by the time you do all those things to it, and put an intake and an exhaust on it to match, it's no longer a LG4. It has become a 305 CID race motor instead. Just because the only piece left that came from the factory (the block) happened to have started out in a LG4 doesn't mean that you now have a 400 HP LG4; a block is a block is a block, and that's all that's left.

Magazine article buildups don't ever tell the whole story, nor do they necessarily mean that they're something you can do to your own street car. I seem to recall one of the mags doing a "400 HP 305" article once; yeah, it did 400 HP, .... once. It blew up on the dyno. Not exactly my idea of a successful build, ifyou know what I mean.

I would not put a "drop-base" air cleaner on anything. If you think about what you're really doing, what's happening is that the intake lid is staying at the same spot as it came from the factory (basically slammed up against the bottom of the hood); all you are accomplishing by putting the taller intake on there is moving the top of the carb up closer to the lid. So you replace a restriction in the intake manifold with a different restriction, this time between the carb air horn and the lid. Zero net gain.

The only solution to this problem is to replace the hood with something taller, especially if your car is a Pontiac, which has an even worse clearance situation than the Chevy version of these cars..

 

This wouldn't comply with emmissions for an '87 Bird.

For the first steps go up to a 3" system, perferably with the late Z dual cat. You will need good headers too. Then build a 350 up from scratch. Like this beast-



I think they made 450-500 horse with that 396. If your wallet isn't to thick, I would look for a 400 shortblock and build from there. To make that kind of power you have to sweat the details, and that can be moocho expensive. Wait till you spend more on the porting and polishing than the actual heads!!!

For power like that start with cubes.

 

Im not sure how reliable it is, but the mods in the sig to my 305TPI comes out to 288hp on DeskTop Dyno.


Ken

 

a more realistic goal that alot of people do and is somewhat a challange outside of power adders is getting a HP per cubic inch, 305 HP is a much more realistic goal, if you want to try and get over that go with a bigger engine.

 

Well, I don't know. But I would probly guess.
1. Full exhaust
2. Heads
3. Cam
4. Intake
5. Valvetrain
6. Supercharger
7. NOS

I think that would create a nice little power making engine. I would love to do that if it was even worth it in my car.
If anyone wants to donate these items listed above to me, I would appriciate it.
Thanks anyway.

Oh, I forgot to add the suspencion mods. I'm probly still missing others though.

 

With carefully chosen quality parts you could probably get close. N/A you can easily get a good 350+ horses out of a 305 while maintaining streetability.

 

Um, I had an Edelbrock 1406 carb and a Performer RPM 7101 Dual Plane Hi-Rise intake Manifold on my LG4 with a 3" drop base Air cleaner and it fit fine.


With this setup, I ran a 14.94@91.67mph in the 1/4mile.

This is the way it looks now,

I haven't started it yet so I don't know how it runs yet.

 

Zepher's carbed pic is a classic example of what's wrong with a "drop-base" air cleaner. It shows in perfect visual form what the difference between "It fits!!" and "It's right!!" really is.

Look at the base of the carb, then imagine where the carb is inside the air cleaner. Think about where the top of the carb is. There is about 1", maybe a little less, of clearance between the top of the carb and the bottom of the air cleaner lid. It's glaringly obvious in the pic.

These cars come from the factory with the breather lid already all but slammed into the bottom of the hood. By putting on a taller manifold and a "drop-base" breather base, what you are in effect doing is leaving the lid in the same place (slammed against the bottom of the hood) but moving the carb up an inch or whatever, the height difference between the manifolds. That means you have just added a new restriction to air flow, in the form of a little slit between the air horn and the breather lid. It doesn't matter how much chrome and filter medium there is around the outside, where you can see how sexy it looks; if the air has to squeek through a narrow slit and then make a sudden 90° to go into the carb, it isn't going to flow.

A L69 5-speed in 83 ran almost a 15 flat off the showroom floor. Zepher's motor has headers, a high-HP manifold, probably a cam, and who knows what else; yet, Zepher's time slip says his car would lose to a bone-stock L69 with the timing bumped up.

I'd bet his car would have been a good ½ second faster if he had put a non-"drop-base" air cleaner on it; faster in fact than what he has in it now.

Unfortunately, the only real solution is an aftermarket hood, which really bites.

 

Most cars will actually perform better with the "drop base" air cleaner in place. It was designed over 30 yrs ago for corvettes
with big blocks and low hood lines. It's shape actually helps smooth out flow as it enters the carb. Works fine with a 2.5" filter element.
On my car there is no difference with the air cleaner in place
or removed 13.44@104.58.

 

When I had the Edelbrock setup on my car, I still had the stock exaust and no headers and I ran a 14.94.

I do have headers and full exhaust now.

Oh, and the open element air cleaner made a huge difference in power, I could feel the power.

 

That may very well be true. However, you went from a LG4 breather to the other, not from a better one to that one; so you have no basis to judge whether that one was the best choice as far as power output or not. Also, as I've seen happen quite often, the "feeling" of power results from the extra noise that comes out of the breather, regardless of whether the car actually went faster or not; all that sound sort of recalibrates the "butt dyno". Maybe you have time slips or dyno numbers to back it up, I don't know. I'd still guess the car would have been a good bit faster with a better air cleaner. I've seen it happen too many times.

Even taking a flat-based air cleaner with a tall element and putting in one of those K&N stub stacks makes a surprising amount of difference. One of our old "budget racer" tricks was to take a stock air cleaner bottom that would fit a convenient sized element, cut it out to where it was hidden by the element, and get a chrome top. Then we'd let the people with the flat-based and the drop-based air cleaners try to figure out why they were getting beat.

On the other hand, a properly designed one for optimal flow wouldn't have fit under the hood. So, you did what you could, but it is far from the best-running choice of parts.

The all-around best breather for a carb setup on one of these cars is the L69 one. It gives cold air and low restriction (better than a "drop-base" open element on both counts). But even with that, I was at the chassis dyno one day while I had a 400 in my 83 car; I had a Performer NOT RPM on it with a Holley 800, and the L69 breather. I had carefully calibrated the carb to give 12.6-12.7 A/F ratio with that setup. Just for the fun of it we decided to try a pull without the lid. To our complete amazement, the car would not even do a pull!! It bogged, sputtered, coughed, and slowed down when we opened the throttle, instead of speeding up. So afterwards I added a 1" spacer between the carb and the breather. I had to step the jets up 4 sizes (about 6%) to compensate. That means that I just got about a 6% HP increase out of nothing more than raising the air cleaner lid 1" on a non-drop-base breather. It went from about 1¾" of clearance to 2¾", and made that much difference. Think how much difference doing the same thing might have made on your setup (which is much worse off as your pic shows than mine was) if it had been possible for you to do so, which since you have a Firebird, you are even more screwed by hood clearance than I am with a Camaro.

Stock L69s did about 15.1-15.2 off the showroom floor, with the same intake that came on the LG4, and exhaust manifolds and stock exhaust too. 14.9s are a far cry from what a stock LG4 did, but don't seem all that impressive viewed in that light. I still think there was some power left on the table in your combo, and that a bunch of it was at the air cleaner lid.

 

Putting aside this argument between these guys about what's better a drop base or not. Just thought I'd let you (the original author) know that my friend put an RPM intake and edelbrock carb on his car and it cleared fine. He had a drop base air cleaner BUT he had a spacer between the carb and air cleaner so it basiclally wasn't even a drop base fit and it still cleared under the hood of his '89 Formula with a regular flat hood, not the cowl hood they came stock with.

Also, that 262H cam won't get you into the numbers you want. My friends '89 Formual has a 350 with that intake, carb, and 262H cam and he's only pushin about 325 rwhp. Get the 268H and you'll have a better duration and lift which will relate to more power in the end and you can still use the stock converter. Definitely use 1.6 roller rockers... they will help out alot. If you have the money for the stall I would even probably go with the 274H cam with a 2200 stall and 1.6 roller rockers.... or even a roller cam would be better than the 262H cam. I've learned from past expierence, at least for me, I take the cam that I originally picked out and go at least the next one up or even the 2nd one up to get what i really want.

Most importantly make sure you have a good set of good breathing heads. You won't get that engine to do anything w/out properly breathing parts.

 

I have the same problem with my new engine. I have an Air Gap RPM intake, a double pumper carb, and a drop base K&N 3" air cleaner. The top of each air horn is dead even with the top of the filter. The only clearance above the horns is the dome on the air cleaner lid. Holley recommends at least 3/4" of clearance.

Would buying a K&N filtered lid be a way of getting around this? Instead of the air making a 90* turn, it would be more like 45*.

Trimming the air horns down would be another way to accomplish this, although it would probably screw with the calibration of the carb. Although the airflow loss would only equate to about 20hp on my engine, I'd like to squeeze out as much power as possible.

 

The Air Gap RPM sits even higher than the RPM intake so I can see your problem. Personally, I would get a cowl induction hood and either use a spacer between the carb and that air cleaner or get a non-drop base air cleaner. You could try the K&N lid but I don't know much about them so I can't help you out with that one.

 

only word worth using....TURBO!

later
tim

 

3 words that negate the word Turbo.... at least for me. Mass Air Flow

 

I have an article from a CHP mag. that detailed a 387 hp 305 sbc that was a streetable engine . If you're really interested I'll e-mail you the details.

 

a more serious reply

i am making about 225 rwhp(calculated) with a stock cammed and stock chipped 305TBI. this has been a really trick deal. i am gunning for 300rwhp after a cam swap and a custom chip.
you can make huge horspower with a 305, the thing to watch out for is how drivable it will be when you are done. if you stab in some huge cam, like you are planning, you will have very little in the way of vacuum because of air flow disruption caused by the narrow bore of th e305. this will cause your off the line performance and around town driving.
to get any real big power numbers from a 305 and keep it drivable you have to use a different engine theory than most people tend to employ. by developing a system of air velocity over the traditional total air flow system, you cna create and engien that has a very high peak torque(this is important since we all know torque is what really moves cars), a realativly flat torque curve, gets great mileage, and is totally streetable.
to do this you will want to stick to lower lift cams(it is best to stay under about .465-.475 total lift in a 305) that have longer durations(something in the 215-218 range will work well) matched to a dual plain intake(a performer, performer rpm or street dominator are all good) intake and some good heads with small combustion chambers to help support your compression(world products torquer 305's have 1.96i/1.50e valves and a 58cc chamber, edelbrock performer centerbolt have 2.02i/1.60e with 60cc chamber, i run the edelbrocks). you will also want to stick with a fairly small carb(600 or 650, double pumper is not necessary but can't hurt if you get one cheap).
once tuned in this will net you some very strong off the line torque and a very respectable peak hp.

hope this helps

later
tim

 

what about a 262h comp cam, with 1.6 ratio rr. Would that improve lift?

 

I think that everyone would be interested in that!

 

jesus, there's enough he said she said to make you puke around here. to top that off there's got to be a lot of rich people here or people who dont like to eat, with all the money flying around on the latest aftermarket goodies. ok first off , what do you want ? a fast quarter mile car or a great performance driving car? both are VERY different animals. if you just want to make a #on a dyno thats easy, a 400 hp 305? not too difficult (honestly) . now where you decide to make that power and what kind of sacrafices you are wiling to make to driveability are where the planning comes in. also if you want (or are willing ) to use power adders is something to ponder. a 400 hp 305 in a weekend is easy. comp nitrous cam, better springs , better coil, new timing chain, tweek the carb, (or new chip for a tpi car), 150-175 shot of juice, have a nice day. treat her nice and only hit it after around 3000 rpm and you should be ok for a wile. same with the blower and turbo basically. i've seen this from people who are tired of getting crapped on by mustangs. to make the #'s you want only on the motor, you need to get creative, and or throw a lot of money at it. now do you want a fast car (1/4 mi) or just a # to brag about? everyone wants a fast car since thats where the BS hits the road. first , find out where your wasting power . you can make your car a lot quicker by chasis tuning and putting the power your making to the ground efficently. body flex, wheel hop, spinning tires, chasis preload, how hard you hit the tires on the launch etc are all factors. next is weight, you either need to build more TQ/hp or lighten up the car or both. these are camaros and firebirds folks, heavy a$$ cars. were not driving vegas or light weight porsches. 34-3800 lbs isnt uncommon for f bodies. lighter components are better, and will go faster with the same power. there's a lot you can do here but, the sacrafices might be more than your willing to make. with all that said, look at the rear gears and a TQ converter, these are probably the 2 biggest things you can do to the car (not on the motor) to make it quicker, period. strength is also an issue here , and that needs to be addressed as well. next is a plan for the motor. with a cam,worked heads (not necessarily aftermarket) , worked intake (has anyone ever even looked down the intake to see if the ports match up with the heads? do it and let me know what you see?) carb or efi, and exhaust mods, 400 Hp is obtainable on a stock bottom end. you dont need a 4 bolt block (i know modified motors spinning 7000 rpm on a 2 bolt block and cast crank that have lasted all season!) or a forged crank, or forged rods, or even forged pistons to make 400 Hp. they might last longer, and give an extra margin of safety , but forged or other hi po super strength parts dont make power. they give you strength , thats what you pay for, strength not power (usually). on a SBC the exhaust needs the most work. cat back systems are great but why bother if the head is the biggest bottleneck? thats almost as bad as us laughing at the rice burners with the 5" exhaust tips. remember an engine is an air pump, you can cram all you want into it, if it dosent come out , it's less efficent and that will cost you power. sorry for going on a tyrade, i just needed to vent after reading so much of the you cant do that with this because the aftermarket gods didnt say so , or they dont make the special hi po unobtainum for that motor. oh and by the way, almost all of the motors i have built have had trouble with the drop base air cleaners they are very restrictive. sorry guys just had to vent a bit , i feel better now, dont hate me too much LOL

 

From CHP mag[Dec.93] 387 hp 305 sbc. I'm just going to print the major stats: 305 .030 os/310 cu. ins. TRW fft pistons, Edelbrock RPM intake,Holley 650 dp[jetted 60/62 still rich]. The cam used was a Air Flow Research with 218/223 duration @.050 and .460/.470 lift ,110 LC. The item that made the hp and I'm sure aren't cheap were the AFR 305 alum. heads with 58cc chambers and 1.99 ints/ 1.55 exhs. using 1.6 stamped steel rockers.With timing set at 36% adv. the engine made 387 hp @ 6000 rpm's and 367 lb. ft. torque @ 4000 rpm's. I think a similar setup using gm production alum. heads 58cc [ported] could produce 350 + hp at a much lower cost. The gm heads have 58cc chambers with 1.94/1.5 valves and have a very effcient intake/exhaust ratio which usally respond better to a single pattern cam. Also Hypereutectic pistons could cut cost on the 350+ hp version.

 

can I port my heads? Or should I get new ones. And Im guessing I shouldnt get a drop base air cleaner...

 

I want a car that gives me fast ETs, and a reasonable number to brag on.

 

I need to knwo the item # of the performer edelbrock intake that will fit my engine

 

vortec heads, performer intake, XE274H cam, 1 5/8" headers, 3" full exhaust, 650 DP, 4.11 9"....mid thirteens @ 104.
That should be around 280 RWHP.
If you want quicker, then you'll need to upgrade the heads.

 

Never mind