I Want 500 Hp Out Of A Chevy 305, NOT A 350, I Want An Answer Not You Should Get Something Else.

Posted in Air Intakes System

I asked this once and didn’t get an answer I know it is possible to get 500 out of a 5.0 v8 hell jaguar has a 4.7 supercharged engine that is in the 400’s . I want to know how NOT GET A 350. I don’t have one I don’t want one. I know boring it out is a bad idea. So Forced induction what ever. I wanna know.

There are 9 Answers for "I Want 500 Hp Out Of A Chevy 305, NOT A 350, I Want An Answer Not You Should Get Something Else."

    1. not pmsmbc says:


    2. ken k says:

      easier to get more horses out of the 350-400 engines than the 305/bigger is better in cu in/engine size in the 305 is like running with your mouth closed /cant get enough air/after that the pistons and cam and valve train needs to be dialed in

    3. apoorapothecary says:

      You run into a plethora of problems with the 305 architecture, trying to push 500 hp.

      First off, you cannot consider the 4.7 Jag to be a benchmark – different animal. Look at Chevy’s 302 – it can put out a lot more hp than your 305. Ever thought why? Well, its a larger bore and smaller stroke – that combination allows better breathing, less valve shrouding and a higher rpm potential – all necessary for high horsepower.

      The 305 is detonation prone at high compression ratios, and cannot flow with tiny valves and tiny bore size relative to the stroke. It also won’t run well past 6000rpm. If you supercharge it, it is equally likely to detonate there, so your potential is limited. Also, the stock bottom end is good to maybe 350-375 horsepower, without mods to strengthen the caps and rods.

      If its a dare-to-be-different and money-be-damned, here’s how I would consider getting there:

      Take the stock 305 block and blueprint it with an 030 bore out. Find a strong rotating assembly and throw out the stock stuff. Get a 4 bolt conversion done with ARP fasteners all around while in the machine shop. Get a good set of blower-capable pistons and thermal coat them to reduce detonation potential. Search around for the discontinued AFR 305 heads they used to make and port match. Get a blower carb set up for E85 ethanol, the best Cometic or Fel Pro gaskets I could source for a 305 blower application, and run about 12-15 psi of boost on ethanol and tune from there. Oh yeah, and I’d source a custom ground cam, since its unlikely you’ll find something to match the combo off the shelf.

      With that, I’d probably be lucky to get just past 400hp, and I’d tune the snot out of it to try to get 450. And I probably would spend about a minimum of 15k getting there.

      305’s are decent motors, but better for mild-to-mid hp applications in light vehicles, and best designed for torque, not horsepower.

    4. nemocamaro says:

      im sorry to say, it is not very likely, but go with some forged internals, port and polish, super charger and some nitrous, and you should get a good amount. if you blow it up, then you can get whatever you want. maybe even a big block. ( they’re actually pretty easy to stuff into some elkys)

      i just got a 85 el camino with the lq4 in it. i was just gonna throw a cam in it and a full exhaust. it should be around 200 then. you have to remember, the 305 only came with 165 atmost from the factory, it will be hard to bump it up that high,

      good luck with the build

    5. Jimbo says:

      Forced induction doesent solve your problems. Unfortunately, unless you have an unlimited supply of money and an extremely talented engine builder to coach you, it just isnt in the cards. The only stock part you could use is the block. 305’s are excellent family vehicle and light truck/van motors, and despite being identical to the 350, just arent cut to fit the bill man. Sorry

    6. eric says:

      well rollers instead of springs in the heads will add some, dual carbs, quaility spark plugs and a turbo charger. theres several things that you can use to get more horse power. i would get a jegs magazine and look at some of the engines they have and what they put on their motors jegs is a very good place to look and if you have questions you can call and they are very helpful

    7. AsYLum dRiVeR says:

      Arawhatever had a good answer, to a point. Get some 1996 or newer Vortec 305 heads. Better yet get a set of 350 Vortec heads with small valves, and run a flat top piston. This will result in a good quench, reducing detonation, while allowing for a low enough compression ratio to run a supercharger. Vortec heads flow better than any previous iron head, and flow better than many aftermarket heads below 500 lift, not to mention a good chamber design that increases efficiency while reducing detonation and other issues. Rods and crank are standard 350 stuff so get a good enough crank and rods pretty much anywhere. (even stock forged will work) It may be hard to find the perfect cam, but something with a bit of overlap will give you a bit of cross-flow, reducing cylinder temps (and therefore detonation), but also reducing efficiency and losing some boost pressure. Careful not to deck the block or heads at all because the stock 305 block will not have thick enough deck surfaces stock to put up with much more than 7-8 pounds of boost. If you do a half-fill of the block you may be able to push that a bit, but not much. I would go to 12-ish at the very most. Even then I would expect to run an expensive head gasket, and make every effort to keep it between the decks, just to replace them relatively often when they squeeze out.

      Try not to compare engines in the future to other manufacturers. Especially those of Jaguire etc. A european lux car, or itallian rolling penis have very different considerations in the engineering and construction of their motors than Chevy’s absolute lowest class of V-8 passenger motors.

    8. chevyraceman_383 says:

      All I know to do is laugh at this question

      I’m a real engine builder, working with circle track and drag racing teams.

      You can listen to me or not. That’s up to you, but I’m gonna tell you right now, they ONLY way your gonna get 500 HP out of a 305 and it live is gonna run very high $$$ and by the time you are done with it, you could have had a 900-1100 HP 350 or 383 for the same price.

      The 305 is limited due to the small 3.735″ bore. You can’t say X brand’s 4.7 or 5.0 L makes this so I know a 305 can too. Buddy, it don’t work that away.

      Bore, stroke, valve size, valve shrouding, quench, etc all plays a part. Look someone already mentioned the 302 chevy. It made 486.4 HP in trans am race trim with cross ram intake, 180* headers, etc. That out powered every small block in it’s time and alot of big blocks. You think thats common?

      The 305’s small bore limits valve size to 1.94″ intake, and you MIGHT be able to fit 1.60 exhaust valves but they will be shrouded BAD. 1.50’s would probbly make more power. With the larger valves, the valves will hit the deck of engine, side of cyl bore because the bore is so small. (Very big diff in 3.735″ and 4.000″)

      That means you are now limited to what heads you can run. Most good flowing heads are setup with 2.02/1.60″ or larger valves. You need heads that flows AT LEAST 255 cfm on intake side and 165 cfm on exhaust side

      Yes forced indcution is a must but still you run into flow probs from the tiny bore, small valve sizes, and lower flowing heads.

      You will have to focus on making power between idle and 4500 RPM cause again the small bore size hurts air flow and power really above 4500 rpm. This runs you into another prob, easiest way to make power is to step up and set engine to run in the 3500-7000 rpm range and make its peak around 6500-7000 rpm.. A 305 CAN NOT do that

      Turbos are out of the question. They take RPM to spool up. You can’t waste RPM waiting on spool times.

      Roots blowers are not eff. enough and heats the air too much.

      Your only option is a Centrifugal supercharger like vortech, paxton, procharger, etc.. Running about 15 psi boost

      Then running a very good intercooler. I would use a water to air cooler

      Also your NOT going to get even close to this with the stock 3.48″ stroke. Look at a 3.75″ stroke and boring the block .030″, making a 334 cid engine

      Ok, now back to the build.. Forged 3.75″ stroke crank (lightened), lighter weight 6″ I beam forged rods, billet splayed 4 bolt main caps, machine work to add the splayed mains

      Forged pistons. Most likly will need to be a custom order so around $800 or so. You need around 8.5:1 compression

      To keep port speed up, and power band where you need it, you will need a 175-185 cc intake runner head
      AFR use to make a 305 head, not sure if they still do, but thats about the only option on a build like this

      Top it off with an edelbrock RPM air gap intake thats been port matched, de burred, etc.

      Use a custom built holley 4150 HP style carb setup for blow through use.. 700-750 cfm

      Cam will need to be a hyd. roller in the 228-230/238-240 @.050″ range and lift as close to the heads peak flow lift (.600″), with a wider 114 LSA

      Oh don’t forget to pull all the tricks out.. 7/8 qt oil pan, trap door baffles, windage screen, alum under drive pulleys, elec water pump, ARP studs through out engine, MLS head gaskets, .038 to .040″ quench height, etc etc. Its gonna take everything you can throw at it to pull this off

      That should get you 500-510 HP @ 5000 RPM from your over worked, 305

    9. david says:

      bore out 4in use block cement fill up block above freze plogs use flat top pistons get stroker kit use elebock alu heads 220runners 64cc or dart heads uses over 500lift hyd cam 780 bubble pump carb victor jr intake shud have 450 to 500hp (best to use 350 4 bolt main block for 383 30 over 388 60 over) 305 block would get to then may bust cylinder