Spoiler:
460 HP!

 

I guess I'm the 305 crowd. The large increase in compression with the domed pistons in the previous video produced a big gain in HP. Now this video's addition of the solid roller cam and Trick Flow 175 heads added another 100 HP, up to 460, from 350+. It's a huge cam, larger than most people would consider putting in their 350s, so the result is a testimonial to those heads.

Unfortunately, searching Summit and Trick Flow websites, it looks like those heads aren't available anymore for a 305. They appear to only be available with 350 valve sizes (2.02/1.6) and combustion chambers. I searched sometime last year for them too, and they weren't available then either, so EP/PN must've gotten those 1.94/1.6 heads a while ago, which takes the airflow out of the sails of 305 owners today.

 

There's you and a few others around here. I've been part of the 305 discussions and once you get past the detractors, there's some decent information exchanged.
That said, yeah, I'm a little surprised that the Trick Flow offering has disappeared. I poked around a little this morning and about the only (but not the only) manufacturer that came up was World Products S/R 58 cc head. Directed at the circle track crowd (which explains it's iron casting), at 225 CFM, it looks to have some potential.

https://billmitchellproducts.com/pro...3fXJUmuoA0oNSW

I think that CFM is comparable to the L30 Vortec head. Speaking of which, they are still out there too.

Edelbrock has their Performer RPM series but there's a caveat to using them on a small bore engine.

https://www.edelbrock.com/performer-...YniGDx2nkixwAT

As for the cam, it's the linchpin in any build. For any small displacement engine to make top shelf HP, RPM is involved though. 7000 isn't that much really although Engine Power going there with a stock bottom end is a recipe for disaster. Even they acknowledged that.
But it shows what can be done. 400 HP out of 305 is a simple formula. An L30 head with a .500" cam, along with the requisite induction and exhaust would do it. And I found 400 HP to be plenty of fun, and 12 second capable as well.
FWIW, my former stock bottom end 350 (albeit with ARP rod bolts), went tens of thousands of miles and saw 6500 regularly.

 

I couldn't believe it. I think they went to 7200 RPM on the 305....I was CRINGING! I thought it was going to blow. When engine masters did "how much boost can a stock bottom end take", on an L31 Vortec, I believe, I was cringing when it got above 500hp....I think it went all the way to 700. But THIS...this was high RPM for stock parts and especially stock rod bolts. Man....I can't believe the thing held.

 

I can kind of hoping for a rapid escape of those stock bits...It would make for great YT content.
Fully agreed on the 7k and stock parts. No thanks.
That said, throw in some relatively cheap Eagle rotating components and if the circle track guys have any input here, the SIR rods I have in the 357 with the less than premium ARP fasteners are proven to be higher HP and higher RPM stalwarts. I'm betting on that being true because my lump is going to see 6500 at least twice on every pass. Maybe three times if I have to step up the gearing!

 

That whole series has been interesting to watch, I think. By series, I mean all the 302 Vs. 305 videos they have done.

 

:shrug:

Same crank as a 350. Why not?

My money says the EXACT SAME $$$$$, whatever they were, would have made 528 HP in a 350; or over 600 in a 400. Meaning, spending that whole SHIPLOAD on a 305, is a WASTE OF MONEY, unless you're in some sanctioned racing class that has a 5.1 liter hard upper limit. If all you want is to go fast, that's not how to do it the best way.

 

Because there is NO WAY in hell I'd go 7200 RPM on a 350, either! Not one that I wanted to drive home, with.

 

Well, yeah, butt if all you were doing was looking for 460 HP on a dyno so you could write a magazine article that would please all the 305 nut huggers and leg humpers, and tempt them into impulse-purchasing a copy at the AZ counter, why not?

 

It's not the crank that concerned so much as it was the stock rod bolts. I'd be willing to wager that after a few of those passes there would be obvious signs of distress upon a teardown inspection.
As for the waste of money. Yeah. Sure. Kinda. But the racing classes aside (I'm suuuuure you're aware how fast a 305 3rd gen Stock class drag racer can go). Yes, FAR more to it than engine, but still. Those guys buzz those things to the moon. Not entirely sure of the reinforcements allowed though. But stock does mean something.
But yes, if all you want to do is go fast, as I did in my late 1970's tech college years, I followed my engine course professor's advice. "If you want to go fast on the street, then put the largest engine you can between the fenders!" So I built a 400. Pretty quick too for the day.

 

I just want to take my 305 and run down my buddy with the 1990 5.0 Mustang GT. We are playing the 90s OBD1 HP games. LOL

 

Waaay back in the day, (before I had that aforementioned 400 SBC), a racer once told me that they'd have their junkyard 350, race and rev the living **** out of it. When, not if, it blew up, back to the junkyard for round 2. Or round 3, 4. Nothing new I guess.
But that's not my deal. Blowing stuff up is hard on the wallet! The 400 eventually let go. That though was the result of a sustained 6000+ RPM open road blast that, judging by the result (a persistent misfire that I couldn't diagnose) floated a valve, bent it then that valve head eventually snapped off. I was left with one cylinder head, an intake manifold/carb and that was it. Everything else was totalled. That's what happens with stock parts (as in valve springs) and the valve head makes the piston disintegrate and the rod enters the block at an acute angle. That was the end of hot rodding for the better part of twenty years.
Yes, I like to drive home.

 

I think the key there is not to be afraid of RPM!

 

Those games are fun. Back in the day, I had my '83 LG4...it went low 15's w/a cam. Meh.
My bud had an '86 Z28, LG4/5 speed. He had a mild compu-cam, Edelbrock headers and Performer intake, it went pretty damn good. He and I were driving home one night from somewhere, going south on 495 (A couple of Mass-holes) and a late '80's/early '90's 5.0 comes up on us, I knew immediately, that I was "out". But my bud down shifted his Z28 and he and the 5.0 went for it. I tried to keep up as best I could to watch/see, and it was a dead heat. Totally cool! Everyone slowed and the Mustang guy hollers out his wondow to my bud, "305 or 350?!" My bud replies, "305!". He got the nod of respect and we all parted ways. Fun times. Fun cars.

 

With the factory LO3 heads and cam, I'm not afraid of 4500 RPM. LOL. I'm trying to find A set of LB9 heads (still not amazing I know) and a L31/LT4 cam. I have a L98 on the engine stand that I've considered swapping in but I kinda wanna stick with the 305 just because....

We've been to the track a couple times screwing around. We were playing with his and put on a belt just turning the water pump, pulled the air filter (his engine is already pretty hashed), pumped the front tires WAY up and even iced the intake down in the staging lanes for 15min before his last pass of the night. We'd have smashed his fuel pressure regulator a little with a hammer if we could have found a socket the right size for a little extra fuel on top end during WOT Open Loop.

It was a really fun night and I'm sure everyone else thought we were nuts.

 

Actually, for quite a few years, the homologated SCCA Trans Am series kept their 5 liter limit, the one that generated the 302 Z28 back in the 60s; and the 305 was the engine they used later on, if memory serves. So, not drag racing maybe, butt other types of sanctioned racing.

My point about the crank wasn't so much about the "crank" itself, as, the stroke is the same. The WHOLE bottom end is the same. Crank, rods, bearings, everything. The L69 even came with "X" rods. So, in all respects where "RPM" is concerned, there's no material difference between a 305 and a 350. Anything a 350 can endure in that dept, a 305 can as well. The 305 will just make about 15% less power, overall, while costing EXACTLY the same, if not MORE (350 pistons are usually the cheeeeeeepest there are, if there's any difference). Kinda like going to the grocery store, and you see T-bone for a price and you have exactly enough money for a pound of that, and you see chuck steak for 15% less; would you walk up to the butcher and say, "I just want to be different, so give me a pound of chuck, butt charge me for the T-bone"? Same thing. If you're paying for something, might as well get as much for your $$$ as you can.

Butt yeah, the 305 itself is a perfectly good motor in a vacuum of alternatives, and can make decent enough power and all that; after all, it's a SBC, same as a 262.5, 265, 267, 283, 302, 327, 350 or 400 in that regard. Has the same benefits, capabilities, and limitations of any of em. If the larger-bore ones DIDN'T exist then we'd all be building 305s and doing whatever they do with them. Butt large bores DO exist, so, that kinda flips the economics a bit. So, just like taking the pile of money we have in our pocket and choosing whichever kind of steak and spending that money on inferior steak, sure you can maybe make 460 HP at 7200 RPM out of some 305; butt for the same money, you can make about 528 out of a 350 at 7200 RPM, with the same level of reliability etc. A 400 will cost a bit more, especially if you want it to make that power at that RPM many times. It's ECONOMICS - "this much money, 305 this much power, 350 more power"; not "305 bad 350 good".

 

Im in a similar position w a bronco w a 500-700 mile atk reman 302. It has flat top hyper pistons and runs great. But its a 302! It has a small cam in it. Maybe some heads? Maybe pull it? IDK, its a little engine. Ive never had a little V8.

 

I've often considered, if I were in that position that forced induction would be the way to go. I'm not a real turbo fan as the appearance just doesn't sit well with me (although a rear mounted turbo is an option) so in that regard a blower I think would be an interesting move.
$$$ for sure. But compact and at moderate boost, say 15 PSI, the little 302 could easily see well north of 500 HP. Closer to 600 maybe if the original engine had some reasonable beans to begin with.

That said, in today's engine world, my 357 is "little" by comparison. I would have really preferred to go the 400 CID, 4.125" bore route but it wasn't in the cards. Had I known what the build direction was going to be once the engine was at the machine shop, at least a stroker crank would have been a better move. But I wasn't expecting new rods to enter the picture. And those, along with the planned for forged pistons, meant a rebalancing and all of that drove up the cost. A 3.75" crank looks like a no-brainer in hindsight (although the heads are much better suited to a 357 at 6200-6500 RPM.)

EDIT: I see you have a centrifugal supercharger already (in your 82 TA) so you're fully familiar with that game.

 

Yeah, i thought about a blower but it needs better heads. It has 8.6:1 comp so it perfect for a little boost but the heads flow like crap so id be 400ish. A 400ish hp blueprint 347 would be about the same price(ish) as a blower! So to sofas point, it doesn't make a ton of sense. Maybe I should just control myself and not mess w it!?! Life is full of these really difficult decisions.

maybe a 347 w a blower!

 

While this isn't of interest to most people, it's still a reasonably fresh thread and video, so I did a new search tonight for the Trick Flow heads for this 305 build, and... they're available again. They haven't been listed for over a year, so I'd guess they've been getting some inquiries because of this EP build. Here they are, and the record stands corrected, at least, for now.

CHEVROLET 5.0L/305 Chevy small block Gen I Cylinder Heads Cylinder Heads Cylinder Heads - Trick Flow Makes Serious Horsepower

And now back to your regularly scheduled discussions.

 

For $1,049.99 per cylinder head they can turn them sideways and see how far they can shove them up their backside.

They got plenty of useless Double Humps for one foot in the grave and the other foot dragging over the side Boomers to buy. LoL

 

The 305 SBC was a small bore and long stroke under-square V8 designed for good low rpm torque without sacrificing mpg. It wasn’t designed as a performance engine. It was designed to pull around, at low rpms, the relatively heavy cars GM made at the time and to increase CAFE numbers.

TPI was designed for the 305 to increase torque for even better performance. When the C4 was being developed in the mid to late ‘70’s, the Corvette was going to have nothing larger than a 305 displacement. When it was decided at the last hour that it would have the 350 instead of the 305, they simply slapped on the 305 based TPI induction system. That gave the 350 almost big block like torque, but choked it up above 4400 rpms. It didn’t matter because the competition at the time didn’t demand it. The Corvette was competitive even with rpm limited TPI 350.

 

The 350 has more torque than the 305. The whole bore/stroke thing is MASSIVELY overblown; torque is the product of cylinder pressure (pounds per square inch) resulting from combustion, pushing on the area (sq in) of the piston, multiplied by the lever arm of the crank (stroke, in inches). Note carefully that this simplifies to pressure × bore area × stroke; which simplifies further to pressure × CID. Torque therefore stays relatively the same for any given CID regardless of their ratio. The only thing that changes, and that not even all that much over a typical range, is the RPM range where peak torque occurs.

The ONLY thing the 305 was designed for, was CAFE; the loss of power, at the time (mid 70s), was considered acceptable. The "improvement" in mileage, however slight, was accomplished by reducing the CID.

As far as "low RPMs", they used the same transmission (Turbo 350) and the same gears (3.08 mostly) in 70s 305 and 350 cars. RPMs were the same between the 2 except to the extent that the lesser CID's lower torque stalled the converter very slightly lower.

AFAIK the only reason the 305 is the same stroke as the 350 is that they only had to change the block to get the smaller displacement, which apparently was real eeeeeezy and cheeeeeeep. They didn't have to make a new crank design as well. In fact the cranks in most 350s and most 305s of the 70s era (the 442 casting) is the same, just machined very slightly differently for balancing. The same one was used in the 267 and the 262.5 also if memory serves.

TPI was introduced on the Vette 350 at the same time (85 model year) as it was on the 305 in our cars. There were NO 305s ever used in Vettes except for a very short time in California cars; no "last minute decided to use a 350" kind of crap. There have always been few enough Vettes that CAFE has never been too much of an issue with them anyway, only emissions in the case of the carbed 305s for CA in the early 80s, which must be met individually and not as a corporate average. AFAIK TPI wasn't "designed" for one and "repurposed" for the other. No doubt they chose the 305 for our cars because they were expecting to sell about 15 times as many at least, therefore ours got CAFE'd. TPI isn't optimum, or even "adequate", for a 305, let alone a 350; it merely seems that for whatever reason, at the time, they considered it "good enough". Of course when superior competitive EFI systems were introduced by other mfrs starting just acoupla years later, GM could, and should, have responded more quickly; butt they stuck with TPI long after it had become hopelessly outclassed and obsolete. Instead of that whole design team keeping going on The Next Big Thing like they should have, they ... didn't, and apparently discontinued the whole stream of development; so, when it became obvious soon enough that they needed to do SOMETHING, they were already YEARS behind.

The TPI Vettes were indeed incredibly fast, relatively speaking, when they were introduced with TPI. I don't know about "big block torque"; maybe equal to a 366 or something, butt nowhere close to even a 396 let alone a 454 (I had some of them at the time, so I KNOW); butt they were AHELLUVALOT faster than most 60s and early 70s muscle cars. People tend to over-romanticize those older cars.

 

I've never read anything from a credible source that states there would be no 350 in the 80's or in '85, or that the 350 was some kind of last minute decision. Anecdotally, the C4 already had a 350 in '84 (and prior)...they (somehow) passed CAFE and emissions with the '84 CFI -while they were developing the TPI....and they didn't think they could do it in '85 with the TPI w/o going to a 305? That doesn't make sense.


Big time. HERE is a funny read, supporting that exact notion.

 

You have to remember the time. In the mid ‘70’s, when development for the C4 began, the consensus was that any V8 larger than a 305 would not exist due to projected CAFE requirements in the future. That’s why when TPI was developed, it was designed for the smaller 305, not the 350. When GM slapped it on the 350, it starved the engine of air at higher rpms because it was designed for the smaller airflow requirements of the 305, not the larger 350.. Yes, it is true. You have to do more research on the subject.

The C3 already had the 350, but that was a carry over design that dated back to 1968. In the mid ‘70’s, GM knew it had to start thinking about a successor to the long running C3 so that’s when development for the C4 began. In those initial stages, it was thought that the 305 would be the maximum displacement for a V8 engine in the Corvette so TPI was conceived. The long tube runner design brought torque levels on the 305 to match the larger displacement 350 of that time.

The ‘84 CFI Corvette was simply a stop gap effort to get ready for TPI in ‘85. However, CFI was similar to what TPI was on the 350. Cross-Fire injection was based on the old cross-ram setup originally designed for the 302 back in the mid to late ‘60’s. Just like TPI was in ‘85, the cross-ram based CFI choked the larger displacement 350. When it was decided late in development that the C4 would retain the 350, it was already too late to redesign TPI. It had to go as is for the larger engine.

That’s why it all makes sense. TPI choked the 350 because it was never designed for that engine. It was designed for the smaller 305 to bring up low rpm torque levels without the fuel penalty of what a larger engine would require improving CAFE standards for GM. When Reagan got in office, he changed CAFE standards by rolling back the fuel efficiency requirements and the 350 was allowed to continue in the Corvette. It wasn’t a last minute decision per se, but it was made late in the game in regards to C4 development which began in the mid ‘70’s.

 

I remember the time. The development of the C4 had nothing to do with TPI. Sorry, TPI wasn't being developed in the '70's, either. Nope, that didn't happen until the '80's. I've done plenty of reading and "research"....instead of me randomly doing "more research", how about you cite your sources that say TPI was specific to the 305 and being developed in the '70's. If that literature exists from a reliable source....I want to see this.

If the TPI was designed specifically for the 305, what was the CFI specifically for? The 265? B/c it also choked the **** out of the 305, too. Look a my screen name. I know some things about the CFI.

 

???

I was there at the time. Not at GM, and not designing TPI, butt still. No research required. Sounds kinda like my kids coming home from school and telling me I need to "research" events that I lived through. Ummmmm... sure, there's things that aren't generally known at the time butt later come to light; butt rewriting history by INVENTING stuff out of thin air, is a whole other matter.

That all sounds like typical Corvette forum monkey-spank to me. I don't recall any "rollback" of CAFE or emissions requirements in that era. In fact those things were tightening year by year; which was the reason for the introduction of computer-controlled carbs, transmissions with TCCs, etc. in those years. And of course, the Vette never was a CAFE (Corporate Average Fuel Economy) issue, since there always so few, that they could get a tenth the gas mileage of any other car and not affect GM's CAFE out to at least the 3rd decimal place. Those guys always like to preen their ego about how important "the Vette" and all the "GM wouldn't allow" crap was. The Firebird people are particularly bad about the flip side of that: "Pontiac couldn't have [xxx] because then it would be faster than the Vette and GM wouldn't allow it". Horse plop, all of it.

GM is, was, and always has been, in business to MAKE MONEY, not to protect the Vette somehow.

 

To improve CAFE, you have to reduce overall displacement. TPI was a way to bring up torque in a smaller displacement engine to move a relatively heavy car (3000lbs) with high (numerically low) rear gears for improved fuel economy..

True, and they could realize better results by more using gears to take advantage of torque multiplication, but this was the mid ‘70’s. Most automatic transmissions at the time only had 3 forward gears and manuals only 4 gears. The 4sp auto overdrive and 5sp manual transmisssion were not introduced until the early ‘80’s. This was still the mid ‘70’s when they thinking about a successor to the C3.

The 305 was designed for CAFE. It was small bore/long stroke engine designed for good low rpm torque and good fuel economy. It was not designed with performance in mind. When TPI came along, it provided the 305 with better performance by increasing torque throughout the rpm range, similar to what a larger displacement engine like the 350 would provide, without the fuel penalty of a larger displacement.

The only reason why the 350 was introduced for our cars in ‘87 was because it was a cheap and easy way for GM to compete with the Mustang. The Corvette already had the 350 which was decided late during C4 development. The 350 gave us an edge in performance over the Mustang. It was cheap and easy for GM, simple as that.

They were only fast in regards to the competition at the time. That’s why GM never redesigned TPI for the 350. It was good enough. The 305 designed TPI intake gave the 350 even more stump pulling torque, similar to what a smogger big block would provide, but at the expense of HP at higher rpms. That’s why low end torque was good, but HP relatively low. The torque peaked early in the rpm range due to the mismatched intake and then power fell off like a cliff past 4400rpms. It got the job done until the competition required a further improvement and that’s when they developed the GenII LT1.

 

CFI was based on the old cross-ram setup from the late ‘60’s. The cross-ram setup was originally designed for the over square 302, not the 350 or the under square 305. CFI was a stop gap until TPI was ready for the ‘85 models. Don’t you think GM would have liked TPI to be ready for the all new 1984 Corvette? Unfortunately, it wasn’t ready at the time.

Yes, TPI was originally designed for the 305, not the 350. That’s why it choked up the 350 past 4400 rpms. Everybody here know’s that

Why would you need it explicitly stated? If you read about these cars, C4 Corvette development, how these engines were designed, the state of the automotive industry at that time in the mid to late ‘70’s, you would derive from the information that is provided that larger displacement engines like the 350 were thought to be on borrowed time.

It wasn’t until Reagan got in office and relaxed the rules on CAFE that mid level displacement engines like the 350 could continue. When it was decided that the Corvette would keep the 350, TPI was already pretty much done at that point so they had to use it as is even though it was mismatched for the larger 350 displacement.

 

"Everybody knows that". Everybody. That's good stuff there, bud. Is that you, "citing your sources"?

Well....thanks for "trying". You must have missed the part where I mentioned that I know a thing or two about CFI. And the part where I mentioned that I HAVE read copious amounts of articles, books, etc. on these cars. I never ""derived" what you apparently think you have....because that was never stated by any reliable sources. You've told yourself your own "story"...and now you've convinced yourself that your story is fact.

Show me where Ron Sperry, Anil Kulkarni, Roy Midgley, or even Dave McLellan stated what you're claiming.

 

Yes. Clearly.

No. It was "designed" to be a smaller displacement engine that could be built on the same production lines using as many as possible of the same parts that were already there. IOW as cheeeeeeeeep as they could possibly make it. "Torque" has NOTHING to do with it, as has already been discussed, because it has basically 305/350 times as much torque as an otherwise identical 350. (given the same cam, same compression, same port flow ratio to CID, etc.)

Possibly true; I wasn't there when the decision was made. Personally I have my doubts though. I'd more likely suspect that some other engine/vehicle combo was discontinued in some other body style(s) somewhere in GM's portfolio of brands, and that whatever that was got terrible gas mileage, such that discontinuing that, cleared out some "space" so to speak, for F bodies to get a bit more "performance" at the inevitable expense of fuel mileage, without triggering the per-vehicle penalties that the CAFE rules demanded.

TPI had/has the same effect on the 305. It uses the "tuning" of the runner length to improve cylinder filling within a certain narrow RPM range, totally independent of CID.

Period, paragraph, end of story. It's not about "Vette"; not about "350"; not about "TPI"; not about "C4"; not about "performance". It's PURELY about MONEY. All those other things are just little details that affect, one way or another, how profitable the products were projected to be. (who knows whether reality matched projections...)

Indeed. That's what I said. Since all the part about Reagan and CAFE and emissions regulations is pure unmitigated unadulterated unvarnished unalloyed HORSE DOOKIE, TPI was built as a replacement for carburetors, that could deliver the incremental annual improvements in fuel mileage and lower emissions that CONGRESS HAD PASSED INTO LAW and Reagan was legally required to set up agencies to enforce, while also delivering an improvement in "performance" that the public was demanding WITH OPEN WALLETS.

Remember?

Don't have to. I WAS THERE. I remember the state of the auto industry. I traded in my 79 Z28 350 4-speed for my 83 L69 Z28, for example. One very close friend and one co-worker bought new 85 Vettes when they came out; one the 4+3, one auto. I remember. I WAS THERE. This feels about like my children trying to tell my parents what happened in World War 2; when they were IN IT.