I know this has already been covered pretty much. In fact I have read over most of the posts that cover it, but the information is so scattered I don't know where to start. Anyway here's the dilemma: I am looking to match the HP rating of the stock 4th gen LT1s to cure my inferiority complex using my stock LO3. I have purchased some MAC headers and exhaust meant for a 350 (so the better flowing 3" version). According to my software's calculations that will add a suprising and seemingly optimistic 30 hp. That brings me up to around 210. I'll be adding an open element but I'll leave that out of the calculations since the results from that tend to vary greatly and will probably make up for some of the optimism of the software I'm using. So, that leaves about 65 hp to go. What would be the cheapest route to go to get this? How close do you guys think the ultimate TBI mods will get me? I'm trying to keep this build fairly simple since this is my only vehicle and I'll be working out of a buddy's garage. Anyway I have a laptop and I'll be making an ALDL cable and probably grabbing one of the moates programmers for a chip so that will open my options a bit. Am I correct in assuming 1st step ultimate TBI? If so, then where to go from there? Thanks guys this has to be one of the most helpful communites on the web by the way.

I suggest getting RBob's EBL system also, if you have the extra money.

Your best bet, is going to be to cam it up. With the right cam, and the right tune, you can make 275hp pretty easily. It might be pushing it a bit on the stock heads, if not, slap some slightly ported heads off a TPI car, or 416's.

Not much else needed, the key is all in tuning it for the larger cam.

Yeah I'm starting to see that on the software as well. Cams are fairly cheap and its a weekend job though the tuning might take a while to perfect. Might as well swap over the heads as well, since I'll have most everything else apart anyway. I'll have to start scavenging the JYs for something to send in for porting.

I guess I'm looking for specifics, like what would be the most cost effective cam to pair with say TPI junkyard ported heads to achieve my goal? I was considering an LT1 cam but I dont see how TPI heads and an LT1 cam will outpower the 350s on a 305 or maybe I'm missing something.

275 crank or wheel horsepower?Cheapest route or the most assured route of success with a low budget?I'd get a set of Summit's Vortec's, and use a 4 inch bore headgasket. Get GM's TBI vortec EGR intake, and a cam in the 208/218 - 218/228 area. Then tune away. You -WILL- have 275 crank HP without a problem. You might be close to scratching off 275RWHP actually. With a bigger cam, you would be above those numbers pretty easily.I know getting a set of LB9 heads is cheaper, but if you screw up the porting job, that could really... well.... SUCK! Personally, I just assume leave the porting to others, and buy a good out-of-the-box set of heads. That's just me, you might not feel the same, and I know a lot of guys here have done excellent at home jobs. If you use non-vortec heads, and I would run a Performer, or Perf. RPM intake and an adapator - but I know Edel's aren't too popular around here either It's jsut what I would do if in your shoes.

I have done it.

I used 416 heads, mildly ported, cam is a 206/216 .447 .447 112, wieand single plane intake, stock TBI unit, with a TDS fuel pressure spring, so I can get 22psi. Then just tune it.

You can see, the cam I used is pretty mild. You don't want to go too radical on the cam, otherwise you will move the powerband into an RPM range, you probably won't want to be spinning. Keep the intake duration down below about 215, and you you should be set.

Really any cam you can pick up, that fits that range, should get you there.

Well, I'm just trying to match or exceed the LT1s rating so that would be 275 bhp not rwhp.

The vortec heads from summit are alot cheaper than I expected. The intake is fairly pricey though. Looks like it would end up being about $600 before hardware and shipping which really isnt all that bad. Add in the rest of the mods and the programmer and I can keep it under $1000 so looks like a good route.

I am not prepared to take on garage porting by any means but I have a buddy whos uncle builds racing motors so he does them for us for cheap. So, having something ported is still an option to save a buck. It looks like the vortec route would be a bit more pricey but I'm sure would yield better results. I am still looking for a bit cheaper than that though. Basically I am not all that much of a cheapskate but I am challenging myself and you guys to find the cheapest route to match the LT1s power rating on an LO3. Partially this is to prove myself in an argument I had a while back about cost efficiency in building an LO3 or swapping to a stock LT1. Also I cant stand driving my friends 4th gen and feeling like mine is so wimpy.

30-40 HP is not a stretch with a FULL exhaust system, using good components. Trucks came with a little hotter cam, bigger exhaust, better flowing induction, and horrible computer tunes, but were still 15-20 HP up on the car version. It is not a stretch to pull 25 FWHP out of an otherwise stock engine by tuning it.

Very true. I might just start with tuning it stock with the new exhaust and open element and dyno it to see where it stands. Other option would be to take it to the track and embarass myself. Anyway I definitely want some kind of hard data after the exhaust to base any future mods off of anyway.

I put a stock 1990ish roller L03 from a Cadillac into a 1987 chevy truck, flowtech 11500 headers, duals, H-pipe, stock intake, ultimate TBI mods, 15 psi fuel pressure, stock accessories, stock 7 bladed clutch fan, etc. With computer tuning it pulled 181 RWHP and 268 RWTQ.

I'm really curious as to what a set of Vortecs(like the ones in summit) a GM performance vortec manifold, a mild cam(LT1 specs, one w/out much lift), and full exhaust and tuning would net. I'm guessing some pretty good numbers.

To the original poster, I think that would be one of the most painless and cheapest ways to meet your goal. And no, my suggestion isn't driven by my curiosity at all

Just in case any LO3 owners are quickly flipping through this thread:

An LT1 (or similar) cam, Ultimate TBI mods, stock 601, 416 or 081 heads, 1.5" headers and 3" exhaust with high-flow (or no) cat should produce approximately 275 fwhp on an otherwise "healthy" L03 305, and assuming that the PROM is properly tuned.

The 187s will make just as much HP. The best head in the group listed above for power is the 601. The best for "bolt-on" capability is the 081.

The 305 Vortec heads flow very well too.

http://www.chevyhiperformance.com/te...on/index1.html

Per "Mission 305" that combination with a warmer cam (.510/0.520-inch lift, 210/214 duration), and ported vortec's made 257.06 hp at 5,150 rpm, 294.96 lb-ft at 3,500 rpm at the wheels... with 280ft/lbs at 1800RPM all the way up to 4600 RPM, there's no reason to go with a smaller (LT1) cam. They estimated 330 Crank HP, and 378 Crank ft/lbs. Here's the dyno chart.


Personally, I think they would have found at least another 20HP and 10 peak ft/lbs with a 3.5 or 4 inch exhaust, but I've always found the 3 inch systems for anything bigger than 3.4L to be a joke while others consider it the "Sabbath Size" for all thirdgen exhausts, so too each his own.

how much horsepower can you gain out of just tuning the L03? Stock?

Thanks GodOverYou, that's interesting, and impressive for budget parts. I picked the LT1 Cam cause it's cheap as hell and there are many of them, plus without upgraded springs vortecs can't handle much lift. That is a very nice flat torque curve indeed.

Good question

I'm interested as well. In one of the articles there is a part where is says that the stock tune can barely support a stock LO3.

do u mean thats how detuned the car is?

For reference, I added a complete exhaust(for a 350) to my otherwise stock Lo3, and picked up about 1/2 second in the 1/4mile. I also added an ignition(crane cams fireball), and homemade cold air(still not finished, so it isnt to effective) and overall I went from a 16.80 best last year, to a 16.28 this year. The car is stock weight, and needs a tune bad, so I think it will go 16.1xx soon. Not bad for just an exhaust, and ignition. Dont know what kinda hp increase that is though.

Was that with or without headers?

Seems like it shouldnt be too difficult to meet my goal really, its just a matter of selecting which route to go. The vortec is starting to look like a very good option.

Thanks for the suggestions guys this thread has been really helpful.

wuuuuuuul.

If your looking for LT1 power, then the graph posted up above is it. Sure, the peak numbers are a little lower than LT1 rwhp numbers, but the power under the curve(or lack thereof) is great. Plus your thirdgen is lighter.

Actually the 275 rating on the LT1s is fwhp so that graph should put it above a stock LT1 by a bit. The thing is it looks like they replaced the TBI if I'm not mistaken and I was planning on just modding mine to the "ultimate" TBI with bigger injectors and pump, so my numbers will probably end up a bit lower.

Either way I'm going to have to look at something better than my factory 2.73 rear end to really see much of this power anyway, so thats another $3-500.

You would have to do that anyways..... 2.73's do make good coffee table conversation pieces though.

whats wrong with your car man? 16.80s? most people can get there 305 in the 15's stock

I haven't seen a stock L03 RS break 16's.... and I see a lot of them at Norwalk. Maybe 20 different RS's a year or so.

16.1-16.7 seems to be about the norm for a stock 2.73 LO3 RS around my area.

Actually stock LT1's are underrated, and produce more whp and torque than you would expect.

It does seem commonplace for tbi cars on this forum to run in the 15's stock, but in the non-computer world I've never heard of anyone running in the 15's w/ their tbi car. I live at sea level BTW. Must be bad drivers, then again tbi rs's around here are very ragged out.

I was a stock L03 auto, running 2.73s, at 1400+ feet. 16.8 is actually good. At sea level it would be a little better. Its not uncommon for LS1 powered f-bodies to run 14.0s here. With a little work a few have broke into the 13s, with the 6 speed.
With. 1-5/8", into 3", hooker headers. I also got the 3" y-pipe, but dont waste your money. Have a local shop fab one up for you.

Yeah i think most who run in the 15s have swapped rears at least with the V6one or better, or at least done some other minor mods. Then again I was reading on another page about LO3 caprices getting about 16.5-16.9 or so stock so we should be down around 16 or high 15s with the exhaust I would think. Then again I don't know how the caprices were geared.

Anyway I'm starting to think my 1st step will actually be to get rid of the garbage I've got turning my rear wheels before I even touch the motor. Would be a good chance to get some rear wheel disc brakes on too.

You need to know that you probably won't see much improvement from the exhaust UNLESS you also tune. I did SLP 1 3/4" headers, dual cats, mandrel-bent 3" intermediate pipe and a Flowmaster 40 series and only picked up 7 RWHP. I'm sure there's another 20 hp in there, but it'll take tuning to unlock it.

Yeah, Thats very true. Tuning is certainly going to be one of the 1st things I will do as I said earlier on in the thread

The thing to remember about that combination, however, is the "ported heads" That was a SERIOUS port job, not just a mild bowl cleanup. Look at the flow numbers, they're better than AFR 190s or even Etec 170s. I called the shop that did the work after the article was published. The guy that did the work wouldn't go into detail concerning exactly what he did, but he did offer to duplicate the porting for me .... for a thousand bucks (labor only)(plus shipping) (two ways).

Once again, a magazine goes to outrageous, megabuck extremes to post an impressive horsepower number.

Oh, and there's no way a 3.5" or 4" exhaust will yield another 20hp from a 305. A single 3" pipe already flows slightly more air than the dual 2 1/2" pipes of the Y-pipe (2 1'4" stock y-pipe). You might as well go with a 6" cat-back for all the difference it would make. Even if you fabbed up a bigger y-pipe, you don't begin to see any additional power with exhaust that big until you get above 383-400 ci.

First of all, a 3 inch pipe DOES NOT flow more air that dual 2.5's. A 3.5 inch pipe does, but that really doesn't matter because the airfow dynamics of moving 8 pulses through one pipe are MUCH different than flowing 4 pulses through one pipe. Secondly, the Y pipe should be smaller to move the gases while they are still hot! Once the gases cool - THEY EXPAND! That means that they require more space. And the expansion is not just from "X" Volume to "Y" volume. They will continue to expand the entire length of the exhaust. The most ideal exhaust would be a pipe that taper's in an ever larger fashion to provide enough space for adequate air speed AND space!

Show me your dyno chart to back up that a larger exhaust made no more power?

I never understood why everyone thinks just because "This guy" makes "This power" with a 3 inch exhaust that those 3 inches somehow are the magical measurement. If you look on the exhaust board, you will find that a 3 inch exhaust was "JUST ENOUGH" for a slightly modified 3.4L V6. But I suppose since 3 inches is the sabbath number, that it should be "Enough" for an engine that's much larger operating at similar speeds .... because you know, so-and-so made "X" power with it. Just because an engine is strong enough to make "Insert some number that impresses you" power despite a shortcoming (exhaust), doesn't meant that the shortcoming is good, or an ideal part of the system. Have those people tried anything else, and if so, where are the dyno charts to back up the claim that a single 3 inch pipe is enough? I could put a big block in front of a 3 inch exhuast and still make 600HP, but I might make 680HP with dual 3's... but that 600HP figure is what everyone will hold onto and be impressed by despite the exhaust holding me back. The tag-line will then be "3 inches was enough for Godoveryou to make 600HP!" but they will never look at the power I could have been making bcause that big 600 just impressed the **** out of them.

There are a lot more McDonald's hamburgers out there than there are TGIFriday's burgers, but which is the better burger? (In other words, just because there are more 3 inch setups, doesn't make them better by virtue of number.) Like I said above, too each his own. I'm just not willing to "Accept" being told 3 inches is enough for any application, without those applications being tested with larger exhausts. If you are, that's your choice. To each his own.



http://www.thirdgen.org/techboard/exhaust/300497-3in-exhaust-3-4-a.html?highlight=v6+3+inch (3in Exhaust on a 3.4....We were so right!!!! :P)
3 inch on a 3.4 made the same power as with the cutout open

http://www.thirdgen.org/techboard/2503822-post21.html
Single 3 inch exhausts cost this guy 10 MPH with just a 350. 10MPH - or about 100 horsepower LOST WITH A 3 INCH EXHAUST!

Compare the two! The 3 inch was ALMOST as efficient as a cutout on a V6 - making it the best exhaust for that engine, but on a larger engine, that 3 inch exhaust choking it. The car still ran 12's with it, which is why you always here "So and so ran 12's or 11's with a 3 inch exhaust, so it's fine for anything in the 12's." But in reality they could have gone a lot faster without it.

I think you need to retake that jr high science class. As a gas cools, it gets MORE dense.

and i am going to point out, there is a LOT more to an exaust system than the diam. of the pipe.

The 3" exaust that you can get from any cat-back manufacture out there, will support the HP we are talking about it in this thread, it will support more too. Yes, you may be able to pick up more HP with a cut-out, but part of that, is that you just shortened the run of the exaust, you also eleminated several bends in the system, and you got rid of that velocity killing device known as a muffler.

Could you gain by going larger, likely. Is 3" enough for most people, yup. Because honestly, you are always going to loose some potential power with an exaust system, its that simple.

Ha... okay, you would be right, but the pipe isn't capped. Okay Dewey, you are treated like god on the TBI board because you have done many great things... so going head to head with you on this point would be like suicide based on reputations, not facts... but hey, I'll give it a shot anyway ... maybe my education is worthless and I should go back to high school, who knows? Maybe that would be easier than saying you might be mistaken once, huh, what the hell?



- Because we are talking about an object of unrestricted *total* space (due to the exit to the atmosphere at the rear), the volume of the air grows, because it takes more energy to increase density than it does volume. As all things in nature do, whatever requires the least amount of energy is what will occur, which is why hot air rises instead of just cooling and becoming more dense. *IF* Mr. Dewey, we were talking about two boxes, of finite volume, than the cooler air would be more dense you are correct, because the volume is restricted. In the situation of an exhaust, there is an exit removing the limit of volume. Secondly, the gases are MOVING. This "energy lost in movement" encourages an increase in volume over density as well.

Creating Density requires more energy than Creating Volume. Simply law to understand, and it's shown every day, as I said above, in that hot air rises instead of just cooling and becoming more dense at the sea level.

Now what happens is when the volume of gases exceeds the IMMEDIATE area provided by the pipe (remember, I'm talking about local area, not total volume), the air will indeed as you so accurately stated, become more dense. However, because of the energy taken to increase density - energy that the gas is rapidly losing as it is due to the decrease in temperature - the gases slow tremendously. The gas is losing energy right from the start, between cooling and movement. When the gases slow, you create pressure, pressure that is not useful 4 feet away from the engine! Therefore by allowing that air to increase density, you are ROBBING POWER from the engine, because you are requiring more energy to be spent on movement than on the creation of volume.

Audio designers use these very basic principles every day in determining port diameter, length and taper for fixed atmospheric conditions. This is why an audio system can sound completely differently in the same room, just be increasing or decreasing the air temperature by 30 degree's. The air has more energy to move in the warmer room, creating a high toned sound.

Forget fluid dynamics - we are talking about air and water, and if you think you are going to build the perfect exhaust with a Jr. highschool education, you would be sadly mistaken.

Next topic - would you not agree that the best exhaust would be the exhaust that allows for the most power to be made? Of course you would, you're a smart kid. Well, for a 3.4L like in the thread below, it happened to be that 3 inch catback. If power can be gained by removing an exhaust, than it is not the most efficient exhaust out there. I think all of us could gain power by removing our exhausts, so obviously, the 3 inch unit is not ideal! It does not provide the space required for that 100% efficiency. If 3 inches was just enough for a 3.4L v6, what FACTUAL evidence can you provide to suggest it will be just as efficient (100%) for a larger engine? I have proven that it is not enough with the thread of the guy losing 10 MPH in a 12 second car. Simply put - there is none other than the blanket statement of "It's enough." Sorry Dewey, just because you say it's enough doesn't convince me, I'd like some data with my Here-Say please.

Sorry - that statement alone does not provide evidence. Logic does however provide reason that if an engine is expelling more air, it will require a larger space in which to expel it in to obtain that efficiency.

I can reqord all that again if you don't catch it this time!

Suicide, nope. In fact, discussion is good. I am the first to admit that I don't know everything, and that I am not always right. Thank you first off, for the well worded response.

Now, this is where i will honestly admit to not knowing everything. My question (and I do mean question). How does your first statement, fit the ideal gas equation? We have temp getting lower (we all admit there is a cooling effect).

Especialy with statement.
So what you are telling me, is that with less energy in the gas, and with less temp, you are going to have a greater volume? (you are saying, a fixed amount of molicules, are going to take up MORE space?)

Now I know that is very much simplifing things.

Its not my goal to convince you. I have sat thru enough dyno sensions, on enough diffrent cars, with exuast systems ranging form single 2 1/4" to dual 3". I have ran my car thru the exaust, and thru a cut-out. I have seen 12 second cars run thru single exaust, cut-outs, and true dual 3".

And I am going to say this. any exaust system is a bottle neck. period. end of story. Your example of a V6, is freakin' Redraif, talk about an unreliable technical source. I have NEVER seen a car that didn't pick up power from a PROPERLY placed cut-out.

I have also seen 3 diffrent 12 second f-bodys, with single 3" exuast systems dyno. EVERY one of them picked up between 5hp-7hp with a cut-out. No more, no less. I have also seen several 200hp cars, pick up that same 5hp-7hp increase, with 3" exaust, and cut-outs.

Again, I am not saying the 3" is ideal. I am not saying it is the best. I am saying, that for most poeple, the 7hp diffrence between that, and a cut-out, is pretty minimal. Especialy considering, you have 4 or 5 almost 90* bends after the cut-out location, even at 3.5" or 4", just having those bends, and a muffler you are going to lose some power.

In case any one was wondering, air expands when heated, and condenses when cooled. I've got the high school physics book to prove it.

I went from 278 RWHP to 301 RWHP with my 312 by using a cut-out. The runs were made back to back, only flipping the switch between. I was already running dual 3" exhaust, dual high flow 3" cats, dual 3" turbo mufflers, and 1 7/8 x 3.5" headers.

Fast, I would blame that on the cats myself. I should have stated that all the cars I dyno'ed had no cats.
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Yes PV=nRT, I am sure his point has to do with the pressure created as you pump more hot gas into the pipe, and you have cool slow gasses exiting the pipe, and how the slowing of the flow creates pressure inside the pipe, and that to move the same amount "volume" off gasses thru a given lenght at the lower velocity, would require more "volume" inside the pipe, to releave pressure at the entrance. (or at least that is what I got from it).

The cats are the likely source, but so are the mufflers. Then again the headers work so much more effeciently when they are open.

On a side note the way I have the cut-outs hooked up now is awsome. I am using RBob's EBL to open them. Connected them through a relay to the nitrous output. Flip on a switch, launch like normal, 10 MPH @ WOT cutouts open, bye-bye *****. Anything under 98% TPS keeps them closed. Awesome for a sleeper.

Your last example was exactly correct.

Okay - let's say we have a jar of oxygen, sealed shut. Into this jar of oxygen, you inject "X" amount of hydrogen. Two minutes later you take a sample. You will not have JUST oxygen, or JUST hydrogen, you will have a mixture of the two.

In an exhaust pipe you have atmosphere and exhaust gases. As the exhaust gases cool, they have two choices, spread (expand) or condense. Spreading of the molecules (expanding) requires less energy. Now I'm going to go a little bit out of my realm, but in the audio design world, we often talk about dust and air pollutants affecting air movement, so I will make what I consider a reasonable assumption. Since we are now going down to a molecular level, there are heavier molecules and lighter molecules. As the gases move, the lighter molecules simply don't have the force to constantly move the heavier ones and eventually lose a lot kinetic energy, but by giving them more space to move, they will move out of the pipe more effectively without causing the impairment of the movement of heavier molecules. What you ultimately achieve is the faster movement of the gases as a whole by allowing them a greater space to exit through.

However, if you force them to condense - costing more energy than expanding into and through the atmosphere - they will exit more slowly than if let flow at a LESS restricted rate.

As far as the 3.4L V6 vs. CutOut comparison... I honestly don't care who it belonged, dyno charts don't typically lie. Remember - I trust facts and numbers, not "It's good enough because Jimmy Bob Dean made <insert impressive number> with it." The fact is, the cutout made almost no more power than the full exhaust - that's what I would consider a well functioning performance exhaust on anyone's car.

Maybe you can post some of the dyno charts through all those dyno runs you have sat through? That would be helpful in clearing up the factual picture

This is the problem I have. That part is not accurate. As the gases cool, it does not spread out.

Ideal Gas Laws say this is not the fact.

remeber PV=nRT

Charles law (v1/t1=v2/t2) states that if the temp is increased, then the volume is increased. per the equation above, if the temp is decresed (as in our example) then the volume also deceases.

Say we have 50ml of gas at 600K what is its volume going to be at 300K ? per Charles law, it will be LESS than 25ml.

50ml / 600K = (X)ml / 300K

The value of X becomes 25ml, this is LESS than 50ml, so our volume has decreased, since our temp did.

I'm curious. How is it that you come in here, make unsubstantiated statements, then prevail on everyone ELSE to post FACTS (which you apparently trust) to back up their assertions? Where are YOUR facts? Where are YOUR dyno charts?

Before you start demanding that people prove their positions, prove your own.

You said:

Where are YOUR facts and dyno sheets.

Here's a FACT for you: Those Vortecs have 64cc combustion chambers. If he takes your advice and puts 'em on there without milling, he'll drop his compression so low you can pretty much write off any power gains from the improved flow.

Then you said:

Where are YOUR facts? Show me ONE example of an L03 going from a 3" exhaust to a 3 1/2" or 4" exhaust and making 20 more hp. ONE.

When I uncorked my intermediate pipe, I picked up only 4 more hp, with NO exhaust. None. ZERO. I guarantee you it was more free flowing than a 4" with a muffler. No exhaust at all is pretty much as free-flowing as you can get.

Then there was this jewel:

ummmm ... excuse me for mentioning this, but when I was in kindygarden, they taught us that things get bigger when they get hot, and get smaller when they get cold. If you don't believe me, get in the shower, turn on the cold water, look down, and see what happens.

You insisted that I post the dyno sheets from my before and after runs to PROVE my assertion that I only picked up 7hp, and I actually started to. But you know what? It's all there. I posted them when I did it. If you want your "proof", then get off your 30-post-butt and do a search for it.

Now, everyone who has been on this board for any length of time knows I am a peacemaker; oil on troubled waters; the nicest guy on thirdgen.org, they call me. But, in this case, I must speak out. Before you start demanding "proof" from people, show us something. Dewey and Fast, while certainly ugly and frequent viewers of Brokeback Mountain, have been DOING this stuff for a long time. They have been making L03s and TBIs go fast for years, and they know their sh*t (in more ways than one). If you're going to slam them, it's you that has the "proving" to do. All you have to do is use your search feature a bit to find out what they've done, and how much they've contributed to this board.

I, for one, would NEVER disagree with either one of them.
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My point, EXACTLY. Charles' Law is irrefutable, for crying out loud. WHO doesn't know THAT?.

Bravo!! Bravo!!!

Well, I have already bought the exhaust. So thats not going to change anyway, but the debate above was very informative nonetheless. So far it looks like my cheapest route after I transplant my rearend is gonna be ultimate TBI and the necessary fuel mods, a cam, some heads... That I already knew though .

I talked to a buddy of mine and he might sell me his heads which he just sent in like a month ago cuz he snapped his truck in half. Yeah I thought trucks were made to offroad too... but anyway. I don't know what casting they are yet but i think he had a decent port job on em. I think they may be 416s or 601s but I am not sure.

So, I think I have a pretty good idea now what I'm looking for.
I think I'm still missing something here because with a 206/216 cam and some mild head work it looks like I would reach my goal according to desktop dyno 2003. What I'm not understanding is how we can outpower a 350 with a 305 by adding some 350 parts with minor modifications. I guess I'm missing something or the minor changes I'm seeing are more drastic than I'm imagining.

How much work would actually need to be done to a stock set of 416s or 601s to reach the flow i need and support that size of cam?

Generally, a 350 setup that peaks horsepower at 5000 rpm will "allow" a 305 to peak at 5500 or so. The extra 500 rpms brings the 305 very close to the 350 with regards to horsepower (within 5-10 hp generally). Do some modifications to the parts (port the heads, etc) and you can outpower the 350 with its own parts.

It all comes down to the fact that parts that are somewhat "restrictive" on a 350 are not so restrictive on a 305. "Low output" 350 parts look a lot more like "high output" on a 305.

It isn't so much as how much flow you need to support the cam, but how much will allow the maximum output that the entire setup is capable of. For example, you might get 275 hp with stock 416 heads (maybe a bit more with 601s), you might get 300 hp with mild porting and you might get 330 hp with heavy porting and polishing. Head flow makes a HUGE difference ...even a few cfm.

Having said that, I don't think you'll get any benefit from more than 240 cfm intake and 180 cfm on the exhaust. 305s don't seem to be capable of "requiring" more than that unless the rpms are spun upwards of 6000 rpm (which is not what you want on an L03 bottom end and hydraulic rollers). That's why aftermarket heads really are not crucial for 305 performance. 601s, 416s and 081s can all be ported and polished to get a 305 (with the proper cam) close to 350 horsepower.

About their being ugly, or about their Brokeback Mountain fixation?

Am I missing something about the brokeback mountain thing?

seanof30306.......


and not about............. (while certainly ugly and frequent viewers of Brokeback Mountain) either.....LOL

You guys lost me......I was simply applauding the smackdown administered by Sean.....No brokebackness implied