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I am trying to get my 92 RS power to as close to 400 horsepower as possible. I have looked into putting a turbo kit on it or a 142 weiland super charger. Does anybody have any suggestions or cheaper alternatives?
I am trying to get my 92 RS power to as close to 400 horsepower as possible. I have looked into putting a turbo kit on it or a 142 weiland super charger. Does anybody have any suggestions or cheaper alternatives?
Cheaper? Nope; that word doesn't apply when it comes to building reliable high horsepower.
Putting a power adder on a 30-year-old 305 with high enough boost to produce that much horsepower is akin to tossing a hand grenade under the hood and shutting it. In order to more than double the engine's horsepower reliably, it'll have to come out in order to replace all the internals with much stronger parts, so it only makes sense to simply replace it with something bigger and much stronger. A crate 383 sound like a much better plan.
Cheaper? Nope; that word doesn't apply when it comes to building reliable high horsepower.
Putting a power adder on a 30-year-old 305 with high enough boost to produce that much horsepower is akin to tossing a hand grenade under the hood and shutting it. In order to more than double the engine's horsepower reliably, it'll have to come out in order to replace all the internals with much stronger parts, so it only makes sense to simply replace it with something bigger and much stronger. A crate 383 sound like a much better plan.
Looks like u won't reach 400hp then. What are some things i can do to boost at least a little of the performance?
Looks like u won't reach 400hp then. What are some things i can do to boost at least a little of the performance?
There isn't much that can be inexpensively done to that engine that will produce more horsepower; Chevy pretty much maxed it out, compliant with EPA regs, with the then-current technology. For that matter, even throwing a pile of $$$ at a 305 just isn't practical based on the ROI from that engine configuration.
Seriously, if you're looking for more performance---that you can feel in the seat of your pants and see on a time slip---you're going to have to go to a built 350 or 383.
If I absolutely had to keep the 305-2V in my Nova--and I don't--I'd be looking first and foremost at aluminum cylinder heads and new pistons. The block gets whatever it needs to repair wear. Hopefully nothing more than bearings, gaskets, cam/lifters, and a dingleberry brush through the cylinders. If it's gotta be bored...it's gotta be bored. But the top-end has got to VANISH in favor of aftermarket parts. My actual plan is aluminum heads, ZZ4-style intake manifold--Q-Jet on top of a 350 Caprice TBI-roller cam block, I already have the heads, manifold, and several core carbs and engines to pick from--I'm just too lazy to do the work.
If you really have your heart set on keeping the 305, there's aftermarket heads specifically for 305. (small valves to clear the bore, small chambers to maintain compression.) That, and a camshaft/lifters would be a good start IF (big IF) the cylinder walls are still pristine. If the cylinders are worn...you're going to pull it out and rebuild it. And at that point, you're barking insane if you don't swap to a 350 or 383.
As far as tuning the computer, that's way out of my league. Someone else will have to help you with that.
It's a SBC Bobby. It responds to most of the aftermarket upgrades that any SBC will.
Aside from the obvious C.I.D. disadvantage Vs. a 350, the inherent disadvantage of a 305 is it's smaller bore. This limits the maximum size of the intake valve to about 1.94". And with a 1.94" intake valve, it has worse shrouding of the intake valve than other SBCs with larger bores and 1.94 valves.
What some of the members above are delicately trying to point out is, if you start with a 305 and X number of dollars, and a 350 and the same number of dollars...all else being equal (short block assemblies in equally good shape), your dollars will buy you MORE horsepower with the 350. You can't beat the better breathing, and the larger displacement.
That said, all is NOT lost.
You're L03 has a very limiting factory exhaust system. Headers, a better y-pipe, and 3" cat back will open things up considerably.
The heads...they are a high swirl head designed for low speed torque (torque peak is at 2400, just above converter stall really), good fuel atomization (runs cleaner), and low spark advance (more fuel efficient as the engine is not fighting itself with high BTDC timing). They did everything GM wanted them to do, and did it well. But they are NOT a performance head. If you envision looking into the port from the back side / intake manifold side, rather than seeing an open port that flows all around the valve guide and stem, you would see HALF a port, as all the flow is forced to one side of the guide and stem, then down a ramp toward the back of the valve....like a spiral staircase. Builds a great spiral, but is limiting in flow. A few people have had luck building an engine with these heads and massaging 300 horse out of them, but most everyone else has found it easier to build horsepower with non-swirl heads.
The cam....your L03 has a very, very small cam, deridingly called the peanut cam. Again, this is great for torque (like an RV cam), saves on fuel, etc. But it doesn't make much power. So a better cam will help. With better heads, you can really take advantage of a better cam.
Improve the TBI and fuel system, intake, rockers, etc. Typical speed tricks will all get you some horsepower. But if you want 400, or an easy over-300 horsepower, the 350 is a lot easier path.
Also remember, your L03 equipped Camaro is further handicapped (from a performance point of view) with either 2.73 rear axle ratio with an automatic trans, or a 3.08 with a 5-speed. A gear upgrade to a 3.27 or 3.42 will make things feel a lot stronger. Torque converter too if it's an automatic.
If you read a lot on this forum, you will find many users that will say that stock for stock, they have found a High Output 305 (L69 or hotter L98 cammed LB9) with a 5-speed to be more enjoyable to drive than a 350 with an automatic. This just means that given a better cam, heads and exhaust, the 305 can be an enjoyable little powerplant. But it has limitations. If you think you can be happy with a warmed up 305 with say 230-250 h.p., then go for it. But if you think you need 300-400 horsepower to meet your needs, you need to seriously consider other options.
Last edited by DynoDave43; 06-09-2019 at 05:01 PM.
the inherent disadvantage of a 305 is it's smaller bore. This limits the maximum size of the intake valve
Originally Posted by chazman
This is SO important. THIS is why even a Chevy-design 307 has more potential than a 305. The two cubic inches mean almost nothing. The larger bore size of the 307 means everything.
The biggest intake valves GM stuffed into a 305 were 1.85s. Anything bigger than that is wasted due to shrouding. Small valves means small ports. Small valves and small ports means very limited RPM potential. Limited RPM = limited power, although low-end torque may be adequate for the displacement. But "adequate for the displacement" is still going to be something like 60 ft/lbs and 40 horsepower short of a similarly-equipped 350. 60 ft/lbs is going to be VERY noticeable. THAT is why nobody with an option chooses to dick with the 305--the small bore CRIPPLES the engine's horsepower potential.
There IS a cylinder head design that will put 2.02 intake, 1.60 exhaust valves into the hopelessly small 305 bore. I own three sets of these heads, two pair installed on engines (a 400 and a 350) and one pair, "new in the box" that will go onto the Nova I mentioned previously. These heads have been out-of-production for about twenty-five years. They pop up on eBay now and then. One of the big hot-roddy magazines did an installation of these heads on a 305 short-block decades ago, when the heads were still being made. I have it in print--somewhere--but I haven't been able to find the article on-line. There were some lift restrictions as well as duration restrictions, but for a stock-or-mild cam they'd clear the bore and improve power. 63 cc chambers, so getting adequate compression is a problem with a little 305. And, yes, valve shrouding was also an issue. Is it worth tracking down a pair of Trick Flow Twisted Wedge Gen 1 heads to put them on a 305? Maybe. At least, they'd fit and work on the 305, and when you came to your senses, they'd fit and work better on the 350 or 383 or 400 you install later. Be aware that you'll need big-bore (4.12 bore minimum) head gaskets to seal the large combustion chamber, and you'll need special Comp Cams roller intake rocker arms due to some goofy valvetrain geometry problems. Overall, not cheap, not optimum, hard-to-find, better than stock.
I have no experience with aftermarket "305" heads, except to know that they exist. They'll have smaller combustion chambers to keep compression up, and small valves to clear the little bore. You could bolt them to a 350 later, but you're stuck with little valves and little ports. A 350 with "305" heads is going to be handicapped.
Honestly, you'd be better-off with a supercharger or nitrous. Choose wisely, and either one would also transfer to the 350+ engine you should be building.
I agree that the 305 is a waste of time. But if you "HAVE" to keep it...
Originally Posted by dangitbobby93
Does anybody have any suggestions or cheaper alternatives?
Dyno Dave laid it all out, very well for you....
Originally Posted by DynoDave43
You're L03 has a very limiting factory exhaust system. Headers, a better y-pipe, and 3" cat back will open things up considerably.
The heads...they are a high swirl head designed for low speed torque (torque peak is at 2400, just above converter stall really), good fuel atomization (runs cleaner), and low spark advance (more fuel efficient as the engine is not fighting itself with high BTDC timing). They did everything GM wanted them to do, and did it well. But they are NOT a performance head. If you envision looking into the port from the back side / intake manifold side, rather than seeing an open port that flows all around the valve guide and stem, you would see HALF a port, as all the flow is forced to one side of the guide and stem, then down a ramp toward the back of the valve....like a spiral staircase. Builds a great spiral, but is limiting in flow. A few people have had luck building an engine with these heads and massaging 300 horse out of them, but most everyone else has found it easier to build horsepower with non-swirl heads.
The cam....your L03 has a very, very small cam, deridingly called the peanut cam. Again, this is great for torque (like an RV cam), saves on fuel, etc. But it doesn't make much power. So a better cam will help. With better heads, you can really take advantage of a better cam.
Improve the TBI and fuel system, intake, rockers, etc. Typical speed tricks will all get you some horsepower. But if you want 400, or an easy over-300 horsepower, the 350 is a lot easier path.
Also remember, your L03 equipped Camaro is further handicapped (from a performance point of view) with either 2.73 rear axle ratio with an automatic trans, or a 3.08 with a 5-speed. A gear upgrade to a 3.27 or 3.42 will make things feel a lot stronger. Torque converter too if it's an automatic.
If you think you can be happy with a warmed up 305 with say 230-250 h.p., then go for it. But if you think you need 300-400 horsepower to meet your needs, you need to seriously consider other options.
My advice for "a cheaper alternatives"?
Junk yard Vortec 305 heads,
*Performer RPM intake w/a 454 TBI throttle body,
*Nice roller cam in the low 2-teens duration
*Headers and a good exhaust.
(*)Parts are reusable on a bigger motor.
That should get you ~230-250 hp and be pretty fun...while you save up for more cubic inches. And you've only wasted about $100 on "305 specific" parts (the heads) at a u-pull-it yard.
I agree that the 305 is a waste of time. But if you "HAVE" to keep it...
Dyno Dave laid it all out, very well for you....
My advice for "a cheaper alternatives"?
Junk yard Vortec 305 heads,
*Performer RPM intake w/a 454 TBI throttle body,
*Nice roller cam in the low 2-teens duration
*Headers and a good exhaust.
(*)Parts are reusable on a bigger motor.
That should get you ~230-250 hp and be pretty fun...while you save up for more cubic inches. And you've only wasted about $100 on "305 specific" parts (the heads) at a u-pull-it yard.
If you cannot get over 350 hp out of that setup you have done something wrong.
I made over 300 hp with the peanut roller. 059 vortecs, thin head gasket, stock TBI dished pistons, 1.6:1 full roller rockers, performer RPM intake, 454 TBI and headers into a dual 2.5 to single 3" exhaust setup. I retarded the cam 4° from its 106 ICL to a 110 ICL. 218/218 flat tappet cam in the L30 in my 99 Tahoe made 280 rwhp. The factory 305 marine engines were net rated with the accessories installed (water circulating pump, feed water pump, alternator and power steering pump installed) at 260 hp with a 196/206 @ .050 cam and restrictive water cooled manifolds, risers and y-pipe. I rebuilt a Vortec 305 in a truck years ago with a Marine 305 Vortec cam amd flat top pistons. Kept the stock truck intake manifold but upgraded to JBA shorties and to the 3/4 ton dual 2.75" exhaust piping and cats. With no tuning it made 230 rwhp and 308 rwtq through a 4L60E. Electric fans and 1.6 rockers picked up another 20.
I like the 305. I generally write off anyone who immediately says to do a 350 swap. in this case though it seems fitting. if you really need 400hp a 350 is the way to go. a 305 can make that hp but at the expense of drivability. if you really just want to get more power and a fun driver with your 305 then there are a lot of things you can do. sure the 305 is a small bore motor but its a small block chevy and will respond well to the same upgrades you would do to a 350. I would start with rear end gears. going from a 2.73 that most 305 tbi cars have to a set of 3.23 or 3.42 gears will feel like adding 100hp easy. its also very easy to change rear ends on these cars. if that still isn't enough I would move forward and change the torque converter to something with a little more stall. a stall around 1800-2000 will help wake the car up. more than that is useless with a 305 anywhere near stock. if that isn't enough move forward again and put an exhaust on it. the stock manifolds are very restrictive and the factory Y-pipe is terrible. you can get shorty headers that will fit well on a thirgen with a matching Y-pipe. the aftermarket headers will flow so much better. they say a set of headers and decent y-pipe can gain you up to 20hp. you would have to make a decision on the cat. the factory cat is a power killer. im going to delete mine when I add the headers. its 20lbs of hp death. the next thing would be more on the "in depth" category. cam and heads. the factory cam is a joke. the heads are only slightly less sad. cams aren't very expensive but you need to get springs and rockers to match. installing a cam is a lot of work that most aren't ready for. heads are a lot easier to install but can get pricey. a decent set of 416s ported with 1.94 valves flow really well. the last thing and I would only do it if you do all the other things would be to put it on a dyno and have it tuned. a good tune can be worth 60hp or more and add great manors. im just saying its a sbc and there are a lot of things you can do to make very respectable power.tarting from the rear is the secret though. adding a lot of motor with a so-so rear end and a weak stall converter wont make you happy.
I am trying to get my 92 RS power to as close to 400 horsepower as possible. I have looked into putting a turbo kit on it or a 142 weiland super charger. Does anybody have any suggestions or cheaper alternatives?
I hate to say it, but what everyone is saying is true. If you want cheap horsepower, look at blueprint crate motors. They sell more crate motors than anyone in North America.
If you can't swap. I suggest a mild cam/heads, longtubes...
it won't be 400 hp but it will definitely pull harder and sound amazing which = fun
Having run both, not exactly true. 305 was 2-3 mpg better than the 350 in the same chassis when the 305 had adequate power to move it. My current 383 build is about the same as the 350 but the 350 was working overtime to move ~6,500 lbs. The 383 also has signifigant tweaks to make it more efficient than the old 350 Vortec. Mainly higher compression, aluminum heads and rhoads lifters.
Having run both, not exactly true. 305 was 2-3 mpg better than the 350 in the same chassis when the 305 had adequate power to move it. My current 383 build is about the same as the 350 but the 350 was working overtime to move ~6,500 lbs. The 383 also has signifigant tweaks to make it more efficient than the old 350 Vortec. Mainly higher compression, aluminum heads and rhoads lifters.
correct. I highly doubt he will be driving his 3rd gen long distances daily. Cruising from street light to street light, or short distances back and forth to work
Its essentially a wash. Its yet another reason people are so anti-305. There are no true benefits to running one these days unless you're looking for a free engine.
A mild cam/heads, with longtubes would probably cure his itch
This is correct. No significant difference. Significant. People will pick out examples to make a point, but the difference will be slight at best and the tune/build/gear etc. has more to do with the mileage than the ~1/4" of bore.
Originally Posted by Fast355
Having run both, not exactly true. 305 was 2-3 mpg better than the 350 in the same chassis when the 305 had adequate power to move it. My current 383 build is about the same as the 350 but the 350 was working overtime to move ~6,500 lbs. The 383 also has signifigant tweaks to make it more efficient than the old 350 Vortec. Mainly higher compression, aluminum heads and rhoads lifters.
I've had both too. In the same exact car, I got 24 mpg with the 305 that had headers/exhaust. I got 24 with the 350, using all of the 305's same components on it. I put in a 400 with ported intake, large TB's, 224/234 cam, same headers/exhaust...that got 24 and on one trip from PC, UT to LA, it got over 25.
That is the essence of "no significant difference". All those results were from many, many long road trips: Mass to U Maine and back many-a-time, road trips to Colorado from Mass, UT from Mass, UT-LA, UT to Denver...that car was driven all over carnation on the highway, and every tank was topped, and all tanks hand calc'd. It's "a thing" that I have always done and still do.
In May, I took my Corvette to Grand Jct, CO for a work trip. It has a 350 in it. On my way back, I topped off the tank in Wellington, got back on the road and decided to drive in "Maxi-economizer mode". Here's what the car said when I got to SLC;
Then I topped it off and hand calc'd it to check. I was crushed when the real, accurate number flashed on my phone calculator. The car had only returned a paltry 33.8 mpg. If only the car had a 305!
06-07-2019, 09:40 PM
On my way back, I topped off the tank in Wellington, got back on the road and decided to drive in "Maxi-economizer mode". Here's what the car said when I got to SLC;
