mustangdmurder

iTrader: (3)

Does anyone know how much horsepower a 305 block can take without dieing on you? The rotating assembly doesn't concern me because I could just buy a forged one for a 350 that would handle anything I could throw at it. I want to build a 600-800HP 305 just to do it, but would the block even be able to handle it? I know I would have to have it made into a 4 bolt with the outer bolts splayed, but even then would it be able to handle 600-800HP?

carattini

I'm no expert but a 305 and a 350 is the same thing just diferent bore size and the 305 have more meet because smaller size so I'll think that it can handle whatever a 350 can handle. Since you said that what you boaght is for a 350 I asume that it can handle it.

NemeSS-TyranT

iTrader: (1)

makes more sense to build the 350 if you want that much hp.
why risk it with a 305. giving up ci and heads and intake selection and potential.
a regular ole 350 will need some prep to live at those levels. dont waste it on a 305.
dont make $en$e with 305. the 350 will make same or more hp with less effort.

Z28ricer

iTrader: (2)

517.8 RWHP

Any more than that, explosions, outside the cylinder walls.

mustangdmurder

iTrader: (3)

Thanks, but curious though where did you get that number?

Orr89RocZ

iTrader: (20)

Block I dont believe is any different than a 350 block, but I have heard the 1 pc rear main blocks are abit weaker in the lifter valley area than the old 2pc blocks.

You should have 4 bolt main caps installed, but I'm not sure if GM ever made a 4 bolt 305 block. The 3rd gen ones arent but you can install splayed mains. It should hold that because the mains arent considered the weak spot. The webbing of the block above the mains is the problem. A few engine builders I talked to say they have seen entire crank with mains dropped out of the block, with the main caps still bolted on! Broke above the mains in the webbing area.

600 is more doable than 800. 800 is asking alot out of a factory block and is why I went Dart SHP and even that is getting high for a dart shp block although some have pushed 1000-1200 in the SHP.

RPMs will hurt it too, 600 hp at 7000 rpm may be more painful to the block than 700 at 5500 rpm, even tho cylinder pressure is very high on high hp low rpm motors. Pressure and then rpms will all distort the block

mustangdmurder

iTrader: (3)

With twin turbos what RPMs would it have to push to achieve around 700HP? I am sorry I am not too familiar with power adders. If a stock block couldn't handle that kind of power does Dart make an engine that could be made into a 305?

Orr89RocZ

iTrader: (20)

That would depend on heads cam used and ultimately boost level. Motor set to 5500 rpm peaks may need 20 psi lets say. Motor with more cam and heads that makes peak hp at 6500 may only need 15 psi. Those are just made up figures, i'd have to run few calcs to make an accurate estimate

If you went aftermarket dart you would build a 400" motor. Block is same price for 350 bore or 400 bore. Cranks being forged are all same price whether its 3" stroke or 3.75" or 4". No sense in doin a small crank large bore motor just to achieve 305 cubes. They dont make a 3.7xxx" bore that the gm 305 uses

A guy by the name of Preston did however build a short stroke 350 that spec'd 305 cubes and made 600-ish hp. He went 10's but not sure if he ever got into the 9's. if he did he probably was closer to 750 hp.

But imo its not worth running small cubes and more boost when at same cost you can do large cubes with low boost to make same power. Its a better mannered motor and less air intake heat from compression at high boost

TurboedTPI

Preston did get into the nines with his 305

Street Lethal

iTrader: (16)

... with Preston it was a 4" bore 305 with a turbo that went into the nines, not a production 305 with anemic bores, as the latter 305 from the magazines allegedly hit tens with 16-psi from a Vortech Supercharger, small injectors, and 3800 pounds of weight, which I always called bull on because there were no slips or videos to prove it. That was back in the early 90's when people still believed word of mouth.

NemeSS-TyranT

iTrader: (1)

looking at a aftermarket block that is close if not over 2000$ after machine work.
for that price you could dig up a stock 4.8, bore it .060 over and get 303ci
(302.77) round off to 303.
use 243 heads, ls6 intake, and just bout any factory cam. ls9,ls6 even stock truck cam and make that hp. on stock block/crank/rods/pistons/rod bolts.
with a turbonetics tc78..
even with a upgraded springs and pushrods stock4.8 or 5.3 will handle that power no sweat on stock aluminum factory heads and plastic intake and stock throttle body.
prolly do whole physical swap and engine build. for what it cost for just a assembled dart shortblock.

Orr89RocZ

iTrader: (20)

Yup. Thats why i feel there are 2 levels of sbc boost or n2o builds. Stuff under 550-600 hp you use stock block, 4 bolt mains.
Aftermarket block, you shoot for 800-1000+ to make it worth the cost lol

Anything between 600-800 is possible on stock block but not great idea and much easier to do on a lsx truck swap lol. Aftermarket block for 600-800 isnt getting the full potential so you are like me and my first build, wasting money. Not everyone needs that big power but you spent the same money for parts either way you look at it. Still need forged internals, still need a turbo and a bigger one doesnt always cost more, most times they are same price. Same fuel system, need a big pump or twin pumps. Only thing you may spend abit more on is injectors. Lol So you spend X money on Y parts for 700 hp or spend X money for Z parts that make 1000. You can always detune boost and timing to keep power out but design for max output

Street Lethal

iTrader: (16)

Your worried about the block at 700-HP, or are you worried about the rolling assembly? Any block can be made into 305 cubic inches, you just need to tailor your stroke to the bore that you have. As for twin turbo's and RPM's, it depends on which turbo's and what cam and heads your running...

Drac0nic

There have been more than a few people hit 4 digits at the flywheel with an 010 350 block (69-79) and some splayed caps.

Hot Rod did a 302 build, I dunno if I'd replicate it (way over headed for the CID, and way under cammed) but it makes a good conversation piece and 550hp at 13 PSI at the flywheel.

http://www.hotrod.com/techarticles/3...yno_test_tune/

http://www.hotrod.com/techarticles/3..._engine_build/

T/Aperformance

How does your response answer the op question?
Why do you bad mouth the 305 so much in so many threads?
We understand your an ls person And good for you, But this isn't an ls question that needs an ls answer. Not everyone wants an ls , some people want to do things with other engine types and sizes than you do.

Street Lethal

iTrader: (16)

Agreed. Nobody spends this much time encouraging others to run LSX engines on websites with vehicles that don't even come with LSX engines without some hidden agenda. Maybe their goal is to sell something, possibly. Who knows. Any engine can be made fast, and why these members insist on embellishing what makes the LSX engine so great over everything else is beyond me. I wonder if they do this on GTR and Supra forums too. There is a reason for everything, and unless they formed some type of LSX Jehova's Witness and are wanting to spread the good news lol, I just can't see what that reason is without having dollar signs behind it...

krisner89

800 hp is bout the limit on a factory small block Chevy. Only problem is to make that power u have to have a 400+ ci engine.

To make a 305 get that kind of power your going to have a rpm at around 8,000+ rpm and a TON of boost. A factory block wont handle those revs. Reason for such high rpm needed is that its a 305. Small pistons will only fit small valves because bigger valves wont fit (they hit the sides of the cylinder wall due to small bore). To get high flow through small valve cylinder heads you'll need lots of rpm and boost to force it through the small passages. That is going to be the limiter.

krisner89

Just found this article for a 305 circle track engine from dart. Notice its a race engine so valves are big as they can be a measly 1.840'' intake 1.5 exhaust

http://www.onedirt.com/news/new-prod...t-track-racer/

Drac0nic

Actually you can put a 1.94 intake valve into a 305 bore without too much issue. There is a thread about heads with 2.02 valves and 305s as well. There are limits especially with aftermarket heads such as those that don't run standard valve spacing. 1.84 valves are likely a class limit of some kind. Several people have run stock L98 aluminum heads on a 305 and to my knowledge they never came with small valve heads.

There "can" be advantages to them in certain circumstances such as less valvetrain weight and if you're using a smaller bore such as a 305 shrouding becomes a concern. I will even go as far to point out that pretty much every production Ford head and I believe a variety of their FMS heads used 1.84 intake valves. This includes on engines such as 351s, not just 5.0s.

A GN can run single digits with smaller valves, 25% less displacement and a very similar bore size of 3.8 inches and do it in a Regal that weighs probably 3500 lbs. I'd bet that's pretty darn close to 800hp at the flywheel. Why can't a 305 do it at that point?

GenX'Motorsport

LOL. I also just read his response in this thread. Im sure that about every thread he posts in. He just bashes SBC's and talks about the obvious advantages of the LS platform. Come on man. Just answer questions and help out fellow Thirdgen Enthusiasts. Thats what this place is about. Every post you make is just negative. Thirdgens came with the Gen1 SBC. Like it, or hate it. If you are actually are a fan of these cars. This is what they are. Lets help members here make informed decisions. And help keep these cars on the road and in the best shape possible.

NemeSS-TyranT

iTrader: (1)

i stated facts. the op is looking to make a huge amount of hp. he is worried about the reliability and structure of the engine at that level.
the ls even the smallest 4.8 has superior heads and structure over any factory 305.
the response was to his question of a dart block. my response was that of a ls alternative.
if anything to save him funds over a aftermrket block build.
it cost me about 100$ to purchase mounts to physically set the ls motor in my rs in place of the 383 the car came with. so its not something that is unusual or hard to accomplish.
i resused the factory motor mounts/clamshells in the car with the ls motor.
looks like it could have came stock that way.
why not direct him to look into a proven platform?
i have sufficient experience with the ls motors, i built them from the ground up for a living even for a while. still build em on the side
the 4.8/ls is alredy way ahead.of the 305 for what he wants to accomplish.
how much money would he have to invest to purchase aluminum cylinder heads to keep up or match even 706?

NemeSS-TyranT

iTrader: (1)

i do actually make and sell parts to use sbc parts on ls motors. not denying that. not at all.
however. i do not sell,offer or pimp any of my products on this forum.
there is no agenda. i made the parts to be functional and actually aid in the swap process of the ls motor. i have no hidden agenda. whatis the problem if i direct someone as i always have to ls motors?. everything i have stated is a fact.
a ls motor is more than capable of handling what the op wants without much prep.
the 305 will require a much more significant leve of prep to accomplish the same task. no doubt about it. why not look into running the ls?
i dont see how trying to help someone go faster is wrong? lol.
if i could run a 2jz in my car for the same amount i have in my ls stuff i would.
however there would be the obstacle of the mounts and transmission.
seeing as how the ls drops in place with 100$ worth of parts and resuses the 3rd gen mounts and will mate equally the same to a gm transmission. i dont see the problem with it. the amount one decides to spend on his project is of his own designation.
but if an alternative is available why not look into it?

NemeSS-TyranT

iTrader: (1)

you are.incorrect about your assumptions about me. i do not bash sbc's. i have a 400+hp full march dressed. iron hump heads 383 sbc in my 68 c10 swb truck. and its gonna stay that way for a very long time.
if you re read my previous post in this thread. i gave my 0.02$ on the matter of the ops goal.
it is an informed decision. the ls alternative is a legitimate response to achieve his goal.
the ls will and can be fitted with minimal amount and effort. parts are available. it is not neccessarily complicated.
i understand that the 350 sbc will require a certain level of prep to handle 700hp.
prolly not as much as the 305 to live at those levels.
700hp is some serious territory. i think we are in agreement that hi hp production here is the goal. if it was a rebuild or re fresh.of the motor, the stock

Street Lethal

iTrader: (16)

"so u think this setup is gonna hold up to at least 550rwhp? thats prolly bout what its gonna take minimum on a full weight 3rd gen that has proper susp setup. i think you should go with the tnetics right off the bat, and not saying that just cuz i sell em"...

https://www.thirdgen.org/forums/post...55-post63.html

A decent amount of people view my thread, so I would say that your post is essentially pimping your products, or using my turbo 305 thread to make it known to those who are reading along that your a turbo dealer. Personally, it does not matter to me. I know guys that are die hard Buick fans, die hard Mopar fans, and freaking die hard AMG fans, and every single one of them thinks their setup is the best. This is what makes for healthy competition. But there is no reason to put an engine down, any engine for that matter, just because someone is electing to build it and you don't agree. If it were me, I would either lend a helping hand, or keep my mouth shut about deterring someone from an engine that they want to build... unless they ask me, personally, for my opinion.

TwinTurboROC

Ok lets set this straight. We (the guys who actually have 305s and are building them to be fire breathing monsters) do not know. The highest HP level I have seen was a 500 FWHP supercharged 305.

As with any motor, The rotating assy, and RPM will be the judge of that. My 200k mile 305 turbo motor has sustained many 20psi short spin ups (not a full pass). Mind you stock untouched from the factory engine.

T/Aperformance

And again you have not answered the OP's question. How much can a 305 block handle. And there is no ls 305 block, Then the op asked about if dart had a block, Again not an LS question. They didn't ask about motor mounts you used for your ls, The OP did not say anything about there budget,
Why don't you stop pushing your ls agenda. Like I said not everyone wants to do an LS build, and if the LS is such a great engine why is GM ditching it And going back to the SBC platform in the LT motor for 2014.
If you can not answer the op's direct questions , if you do not know, then just don't chime in, I'm tired and I know other are also when you jump in and start talking about LS stuff when we are all talking about SBC, If we want to know about LS we can read that in the section about LS.

NemeSS-TyranT

iTrader: (1)

are they gonna go back to an opti spark too?
gen 5 is a evolution of the ls motor. fyi
lt.is just recycled gm speak for motors. no need to get worked up.
im sure there is a few guys out there who have had success and will continue to with a 305. guess ive just gotten spoiled with the ls series. i guess 13+ years.of messing with em. will do that.
i will never know from first hand exp what a 305 will handle.
carry on

NemeSS-TyranT

iTrader: (1)

i did state that i sell them as i do. the reference was in relation to the turbo being used. the intention was not to sell any products. i dont believe you replied to my question in ur thread.i thought you just ignored it, but i guess not cuz you sure did bring it up here. regardless, i hope you hit your goal with your build. would be cool see it break off some 9s. i guess ive decided to take on an easier path at least for me. carry on and good luck.

Orr89RocZ

iTrader: (20)

Is it me or does every 305 thread just turn sour? Lol

rdsxfn524

the water u dump it in Lmao but are how many main bolts are there

UnstableAviator

I believe the OP's question is unanswerable. Nobody really builds or pushes 305's and like any engine there's no magic number in which parts always fail.

The real question is what are you gonna do with all that power? Spend money first on rearend, suspension, safety equipment, and other drive line components. The engine combo ideas can and will change, but the other good parts you can use for years.

Street Lethal

iTrader: (16)

It can be answered, and the answer is... that it depends on many variables. Detonation kills engines, so the hotter the exhaust gases, the hotter the air temps, and this includes engine timing, as many things effect how hot the engine runs. Another factor is vehicle weight, the lighter the vehicle, the less load the engine needs to pull, and that equates to less heat being generated during vehicle motion. This is why we run methanol and Intercoolers. Air/fuel is another thing to monitor, keeping an Open Loop idle set to 14.7, then making sure your fueling is there during your rate of acceleration under Closed Loop monitoring, then returning to Open Loop again when Wide Open Throttle is applied. More fuel cools things off, which is why we target a richer air/fuel ratio when using boosted applications. But getting down to it, the better question would have been not how much can a 305 block handle, but how much has a 305 been able and known to handle through various builds...

Street Lethal

iTrader: (16)

This is something I can't stress enough. Many people will tell you that it takes approximately 10-15 horsepower to gain a tenth in your ET, but adding that horsepower will only increase the possibility of detonation because horsepower is heat. So what do you do when your 305 makes 550-HP with a power adder, but you need to make 600-HP to reach your goals and you don't want to stress the engine any more than that? This is where lightening the load comes into play, as every 100 pounds normally equates to that same tenth for every ten horsepower being added, so rather than add fifty more horsepower to your 550-HP to reach that 600-HP goal while adding more heat and stress on the engine, why not go the other direction and lighten the load, and try to take off a couple of hundred pounds. Horsepower obviously stays the same at 550-HP, but your ET changes, and your temps get lowered. Again, so many variables...

GenX'Motorsport

I think member (NUFF NUFF) with the blue blown 355 IROC car made 700-800RWHP when previous owner, also a member here (Z-DADDY) owned the car. Did it with stock bottom end 305 to about 600+RWHP. Then rebuilt the 305 and went way higher. Current owner built the TPI 355 with AFR heads. Car was also recently featured in GMHT. I think just about all of us know his car

Orr89RocZ

iTrader: (20)

Didnt know the history of that car. 305 to 600? Awesome.
On a side note, i am buying a 305 drop out. Hehe and i have a turbo setup, and sunoco 110 available

Street Lethal

iTrader: (16)

I don't think it made that much with the 305, pretty sure it was close to 500 though with the supercharger, but no more than that. Maybe someone can invite him into this thread for some clarification though...

Do it mon... do it. I would love to see more and more turbo 305 builds...

GenX'Motorsport

^ Nope. It was over 600.. I idolized that car. lol

Street Lethal

iTrader: (16)

^ Hard to say, as even the owner couldn't confirm it for sure. Justin brings out a very good point too in this particular thread (see attached), as his bigger engine made less with twin turbo's at essentially the same boost level. I mean, YSI Superchargers flow very well, but at 15-psi, I doubt it made as much as the owner was stating with a 305, ESPECIALLY at that RPM (4800???). The math just doesn't add up, but I could always be wrong though, which is why I need to see a dynograph, or a track run to see what it trapped...

https://www.thirdgen.org/forums/tpi/...p-numbers.html

Orr89RocZ

iTrader: (20)

My first combo being afr 195 heads on 400" and a 233 deg hyd roller might only have made 640 on 12-12.5 psi but that was a conservative tune and on a local mustang dyno thats been known to be stingy... I know everyone states that but a cam head ls1 car made 70whp more on a dynojet same day vs this mustang dyno. Plus i was feeding thru a th400 and high stall. Not a hp favoring setup

Regardless it went 9.86 at 141 at probably 3550-3600 lbs raceweight. Definately 800-850 crank hp imo.

I dont see any smaller motor making those numbers on similar boost. Just my experience and i hope to find out what a stock 305 longblock but maybe with cam and intake will do with twins or a single 70 off my current setup. We shall see

Street Lethal

iTrader: (16)

Gonna have to ask Joe to make a turbo 305 database as a sticky soon and track all of our results. Other than a T78, I also have access to a T88 turbo that is just dying to find its' way onto my turbo 305 setup right after the T72 does its' thing at the track. Just as a test, with spark reference set to 14* BTDC in a chip I was toying with, with the throttle blipped it SHOOTS up to 6000-RPM instantaneously. Gotta get the EBL-P4 here and start tuning this thing asap...

NemeSS-TyranT

iTrader: (1)

op never came back.

project89

iTrader: (1)

compressor size has alot to do with it as well .
just for example last year v6 member fasteddi was running a 56mm compressor on his engine and at 18 psi it went 13.30's
this year hes running an 61mm compressor and its running 13.0x @ 9 psi and with a bunch less ignition timing


so its hard to compare once setup to another unless things like turbo sizing intercooler efficiancy and other factors are the same


gn heads flow 124cfm and those guys can make 5-600 hp with 20-24psi of boost with only 3.8L of displacement , i dont see why a 305 with a bunch more displacement and heads that flow better cant do it as well

project89

iTrader: (1)

hell 305's are a dime a dozen , get a motor pull the heads and pan , open the top ring gap up , tq the mains an additional 15ftlbs , tq the heads to 80ftlbs (cheapo felpro blue head gaskets ort a set of victor rienz black head gaskets ) and let it eat , who cares if it blows up a replacement engine is only 50-200 bucks away


same thing we do with the 2.8-3.1-3.4 engines push them to a boosted 350-450hp if it blows go get a replacement motor for 50-100 bucks

Orr89RocZ

iTrader: (20)

Regardless of compressor size a small motor would still have to pass the mass flow to produce the power. I dont see it happening. If flowing more air by compressor alone was a key factor then why not try an 88mm if you could spool it? Lol i know thats not how it works but just saying a mild small cube motor would have to magically transform a given cfm into much more hp than my motor did. Basically make more hp per psi. My setup was not special and for all i know maybe it was a turd for the parts. Regardless a 95 cube advantage comsidering AFR heads that do make good use of airflow and a custom grind by a cam guru Mike Jones, compared to a LTR 305? I think the big factor is th400 with high stall vs t5 trans. Bet theres 100 hp difference on the ground at that power level
But whatever, none of this matters to the question at hand. I believe those numbers can be done

My combo did not gain and actually lost power and or spool time with twin 70's over twin 60's in the same turbine housing and wheel and same brand/model turbo. No other changes. It was interesting to see as i considered a 60mm on smaller side for a 400" motor and 70 mm seemed to fit the compressor maps better. Go figure. I think the smallest turbo that can spool the fastest but still make the hp goal is the best bet, and finding that may take some trial n error

project89

iTrader: (1)

i wouldnt doubt that a trans swap would have made 100hp or better difference in ur old combo , thats why im going to a powerglide in my iroc no more th400 or 4l80 for me , the 4l80 will be reserved for the salt flats


i dont trust dynos to much to begin with , my car dynoed 270rwhp/370rwtq @ 9 psi and it runs bottom 12's @ 118 if u do the calcs on that with a 3522# race wieght it dont add up , granted we had some ignition system issues on the dyno but i dont see that making me magically lose 100+ hp on the dyno

Street Lethal

iTrader: (16)

Actually, it does. I don't doubt a smaller engines ability to make the numbers, the only thing I question with that particular 305 build was the 4800-RPM peak at that much horsepower and boost pressure. I would need to see the graph, would need to know peak torque (which would have been through the roof, which is why I doubt the claim), and then finally would need to see a trap speed to believe it made that much power at that much RPM. Incidently, compressor flow alone does in fact make for a tremendous difference. A good example of that is my buddy Scott's White T-Type, running a 3.8 V6 Buick engine, 76mm Turbo and XFI. Also runs a Turbo 400. I know what it traps, and where his RPM's are at the finish line, because I know the car very well...

750-RWHP/787-Foot Pounds @ 25-psi spinning it up to 6400-RPM...

... at 15-psi the engine made low 500-RWHP spinning it to 6000-RPM.

Orr89RocZ

iTrader: (20)

If larger compressors meant more power then how come my 70's didnt out run the 60's? I had to run 3-4 psi more just to match trap speeds and my 60 fts dropped because of delay in spool. Down 2-3 mph in the 1/8

There is a point where too big falls off the effiiciency range and hurts power just as too small you can choke turbo and limit power

mustangdmurder

iTrader: (3)

I have actually considered that because I have 3 010 350 blocks. haha

mustangdmurder

iTrader: (3)

I think they all do. haha And I have another question if I were to build a turbo charged 305 to say about 500HP how streetable would it be? Sorry like I said I am not very familiar with boosted engines.

Street Lethal

iTrader: (16)

This is where hanging around the Turbo Buick and Supra guys have really paid off for me. Lets just say that there is a reason I went with the camshaft that I did in conjunction with my valve size, port work, compression and RPM range. I can't give it all away ya know lol, but I will gladly spill the beans after I post my first dyno video. I am that sure how much my 305 is going to make...