BrandonSB

so, here goes. Ive got an 87 Z28 With a 305 right now, i wanna swap in a big block. i talked to a guy at work, whos been in the industry for about 35+years and hes telling me to go small block, he says big blocks dont rev high enough, and you can get the same amount of HP out of a small block for the same price (about 6200$), and the "sound" is all in the gearing, i dont want a strung out small block that i hav to rev to hell to get power and runs hot.., i like torque.. but i also like speed. is there a balance and which ones more street friendly? i like the big blocks cause of the sound and the power they make at low RPM's but i want something that sounds nice, but is powerful when it has to be.. now i know our cars are fairly heavy, about 3200lbs.. so would big block be the way to go by throwing the torque at it quick generally will be a street car.. enough to put the rice burners in there place. i was thinking a 496. or would a strung out small block be a better option? looking to put TOPS 6200$ in the motor(only) for now ( power adders later on) whats required in order to put this kind of power behind the wheel? what would be my better option? whats more fun? whats your experiences? help me out guys! i basically want a big block (496 preferabbly) that i can rev high enough to produce power.. any options? suggestions?

somewhere around 500-600HP? with gobs of torque.

torque_is_good

Honestly, if you really have $6200 to toss at it, go buy a 4th gen Z28 and put on long tubes and a cam. I don't know pricing in your area but you can pick up 98 and 99 Z's For $4k-$5k around here and that gets you the LS1. Sure, the engines and tranny probably haven't been rebuilt and will need to be soon but you'll get bang for your buck

Air_Adam

Mod for mod, a big block will always make more power than a small block - more cubic inches = more power. Once you get up to about 400hp, it gets alot cheaper to make more power than that with the big block than the small block.

An engine's ability to rev is all in the strength of the bottom end to withstand the rpms, and the camshaft being able to let the engine breathe at those high rpms. In short, you can make a big block rev like crazy with the right camshaft, whether its a little 396 or 427, or a big 502 or 540. With the right cam and heads, it will rev if you want it to.

Sound has nothing to do with gearing. It has everything to do with heads, cam, compression ratio, and exhaust system.

camaronewbie

If I had that kind of cash lying around, I'd be all about a LSx swap - small block motor size with very high power potential.

MassD

iTrader: (1)

thirdgens were not designed for big block chevys. If they were they would have big blocks. The extra weight would upset the balance of the car. For the power numbers you are looking at you can easily get those out of a small block with nothing to radical. Especially if your looking into power adders. A big cam in a small block sounds just as good as one in a big block and you will have enough torque to turn your car into a pretzel. I vote small block all the way because all the extra money you would have to spend to put that big block in a car that it wasn't designed for could be put into making a stouter small block.

Irockz

iTrader: (1)

All of the talk about a BB being too heavy for these cars is pure wivestale.The only way that the handling difference would be noticable would be in an extreme situation,such as autocross.

As far as a cost difference putting a big block in vs. a smallblock,there is little to none.The only component that is significantly different are the headers,and the hooker swap headers really aren't any higher than a good quality set of small block headers.

Dollar for dollar,the big block will give better performance and more driveabilty at a given power level than a small block.That said,I would also agree that given the budget stated,I would also lean towards an LS swap.

BrandonSB

LSX Bowtie, 496 bowtie? power potential and High Rpm's Correct?

it would obviously still produce the same sound as a big block.

but the aftermarket block would be quite pricey wouldnt it? i would probably exceed my 6200$ budget correct?

id also like to keep it TT safe for the future.

BrandonSB

bump, any ideas?

what price range am i looking at for a LSX454.

open to FI in the future.

cuisinartvette

Check into Pace Performance, GMPP, Scoggin Dickey. They do sell the LSx454, nice piece. Cubes+lightweight.

No Lt1 with headers cam etc will come anywhere close to a BB no way to compensate for lack of cubes.

I went the high strung sbc route and while they can be fun you are way better off throwing cubes at it in the first place.

Get yourself a real good cyl head dont cheap out there, 2 or 4 bolt main 454 block up to you. 2 bolts can be found for $100 on CL if you look (I found 2 this week). Use the truck rods, source a good dual plane from the local CL or swap meet, a NEW carb, and away you go. A healthy hydraulic flat tappet or solid will keep the budget down and youll still make plenty of power. Only thing that will cost a few bux is a good alum head if your concerned about weight. If not a set of iron 781s can be ported to make some very respectable power. However youll pay through the nose to have that done, professional quality porting (especially iron) isnt cheap. Oval; ports are the ticket by the way.

I say do it, should be a blast. Forget whats trendy, gas costs what it does, so what. You wanna have thrills with it or go smaller and wish you went bigger because of whats more common to build?

torque_is_good

You keep tossing out models of engines.

You also keep insisting upon forced induction and 600 HP

May we assume that you don't want to run with only 4 pounds of boost? With that said, then you need to build to handle perhaps 10 pounds or maybe more. It does not mean that you will run with that much boost but you must build for it.

So, let's just look at the engine that you need to handle the boost, and to benefit from it. Rememeber, you must do it right from the get go. it makes no sense to tear it all down when you get your supercharger.

What does that mean? it means that every single component inside the engine must be touched and ...................replaced. You can't go get one of those $500 van engines and think you can slap on FI. You will also be springing for good heads. You aren't talking $2k, or $3k, or $4k or $5k to build an engine for 600 RWHP. You'll also be replacing your tranny and rear end and doing suspension work because you must support the power.

I suggest that since this project is probably still in the "formative stages" that when the weather is nice, you drive to the local 1/4 mile track, find some guys that run flat 10's or high 9's (without nitrous) and ask how much they have into their setup. Chances are they can't even remember. You see, those vehicles will be stripped down in weight so those are the guys that you want to speak with for a few minutes.

Then, when you discover that you will be spending well north of $10,000 and I mean well north of $10,000 to correctly(operative word is correctly because you want it to be on the street and reliable) do your project you can make your decision.


good luck

BrandonSB

again as i stated previously that i have about 7000$ to throw at the engine right now. not concerned about how much i actually throw at it, thats engine ONLY. ( like i mentioned, not transmission and suspension)im notconcerned about boost right now. but may be later.

cuisinartvette

Would build the boosted motor now or build one to remain NA


To do a boosted engine right youll need a lower cr blower quality piston/cam.

It will drive but it will be a bit of a dog until you put the F.I. on so if you ARE for sure going to boost it build it once. Should you decide the blower is too much youre stuck with a soggy motor.

You could probably do a motor for 7k without a problem if youre careful meaning longblock only, "little stuff" (injectors tune exhaust valvetrain pieces etc whatever other things you run into) can make the cost creep up though.

five7kid

iTrader: (14)

The bare LSX454 longblock is $10k. Turnkey is $17k. 700 HP.

$7K will get you the 480 HP LS376 crate. http://sdparts.com/details/gm-perfor...parts/19171224

Even 480 HP is a HUGE step up in power over a 305.

Frankly, I'm concerned with liability giving you advice. I don't think you're ready for more than 250 HP. Maybe 300 HP on the track with strict adult supervision.

torque_is_good

that is an excellent point and it's as good of time as any to bring it up. At the risk of PO'ing the OP, I believe this to be a hypothetical discussion and not serious at all. If anyone honestly had $7,000 cash on hand to spend then they aren't seeking help from an on-line forum. They are out talking to shops. However if others are following along, they can learn.

My take on this hypothetical topic is building a 600 RWHP normally aspirated engine. Also, that engine must be capable of being driven on the street with decent characteristics. So, that rules out any small block and brings you into a very large displacement engine.

The discussion also brings into light that hypothetically, the engine may also get FI later on. In order to get an engine to 600 RWHP (about 700 FWHP) then you are running a very radical lift cam, very expensive heads or are using a 600 CID block. Again, it must behave on the street. However, you are building it normally aspirated so it will be spinning high rpm's to make that power. That means a specific type of cam/heads and high compression

If you are going to use forced induction, that stuffs the air in at low rpms and you can't be running an 11:1 compression ratio (well you can but you'll be injecting alcohol or running race gas). It should be more around 9:1 with a different cam and heads.

So, for this hypothetical scenario, it's best to move forward from the get go and set your goals/objectives and build for that.

If it's to be able to reach 600 RWHP then you could get there with a 383 and FI. If it's to have 600 streetable RWHP normally aspirated then it's big block time.

If it's to build a 1000 RWHP then it's forged everything with a ton of boost or big block with boost (again, streetable)

I think too many people are watching fast and furious or playing video games. The posts are made so cavalier with no comprehension whatsoever what it takes to reliably make 400HP out of an OHV engine, let alone 600.


FWIW, on the Honda Accord 2.4 liter they make 1.3HP per cubic inch. If you translate that to 350 CID you get 455 HP. But, go look at the technology that Honda uses to get there. Ford did and that's how they came up with the new 5.0 that makes over 400 HP. Those are what one would call modern engines and cost a lot of money.

BrandonSB

dont think i need a longlock do i?

http://paceperformance.com/i-6255536...tie-block.html

Max. 4.250" reccomended stroke


Capable of 364 to 482 + C.I.D.

this will fit will it not?

i was also thinking about checking out the local scrap yard aswell. i know im going big block for sure, and keeping it streetable (5-600hp) i beleive i can get that out of a mild 454, nothing to extreme (beats the hell out of a strung out small black) the lsx blocks can apparently rev to 7100RPM redline.

maybe what another 1000$ in machining?

1000$ rotating assembly (cheap)

1500$ aluminum heads. (AFR,PATRIOT)

ive never owned an lsx454, but do they sound like a big block, being a small block.

BrandonSB

dont worry i wont get mad, but this is a serious topic. i just like to hear what everyone thinks, because i know there are some guys on here that have done this, then go to a local shop who doesnt have much experience. ill go to both, and what i find satisfying ill build. im just a really good saver, i work hard and alot of overtime for what i have. i understand maj of people are bsing on forums and dont have crap.

pretty decided on the 454 LSX bowtie Swap. sounds good (like a big block) and gets nice power.

yes i understand it might be a big step from a 305, but you also have to assume responsibilty for your driving. dont be an idiot. it will be street driven, but i have respect for other peoples lives to not do anything stupid with the power, it is a mere street car, track ocasionlly (spelt that wrong lol)

BrandonSB

liability? you wont be held accountable for anything, your simply giving mere advice, and im the one who decides whether to take it or not. how could u be held liable?

BrandonSB

i really appreciate your help vette. youve posted a TON of good information for me to decide on. i love the sound of big blocks, and the spool of turbos. im pretty decided!

cuisinartvette

Cool! Hey, if you can swing the lsx454 then go for it, that will keep you busy for a long time think youll be happy with it. Once you experience the power you wont care what size it is how high it revs (you wont have time to look at the tach anyway) or anything else youll just have a big chit eatin grin on your face.

Just get yourself a sticky tire, decent brakes at that level a street tire is an accident waiting to happen;take your time getting a feel for it so you dont get bitten
Youll find when you get something with real power you wont want to squrrel on the street as the roads to "get narrow real fast". Youll see lol.

BrandonSB

hahaha sounds like a lot of fun! so i can build off of that bowtie block? it will be able to handle turbos? what would u suggest i get for parts?!