This is something I’ve been curious about, and I’m sure there are many different answers, which is why I put it in IMHO instead of GQ.
From the early-70s to the mid-80s (or later, even) Detroit produced a lot of cars with big V-8 engines, which didn’t make very much power due to the new emissions standards, etc. This meant some cars with appealing styling (tastes vary…), but not the performance to backup the promise. Because of this, they’re not generally as desirable as 60s cars, and can be had reasonably cheap.
Are there any fairly straightforward things that can be done to boost the power?
Price is a factor, so the most bang for the buck is ideal. Is it as simple as getting a well sorted carburetor? I’m thinking of answers in a few different ranges, from “tack on this bit, and replace this other thing” level of complexity, up to full rebuilds.
It looks like reasonable crate engines can be had for $5000 or so, which puts a limit on the rebuild price. There may be advantages to keeping the original engine, but at some price a complete swap would probably be better.
I know upping the engine power might require a new transmission, rear end, etc., but for now I’m just curious about engine modifications.
First you need to make sure that your area isn’t under emissions testing. If it’s not, you have some latitude even though it’s probably still illegal to make many mods. Also some areas only test vehicles which are 1996 or newer with OBDII connectors.
I’d probably start with the exhaust system. Many were very restrictive back in those days. Something as simple as replacing the catalytic converter with a piece of pipe can work wonders. Of course you may have trouble finding someone to do this as it’s technically illegal. Headers might be an option also.
Next if the engine has a mechanical air pump, removing the belt to it might be worth a good 5 hp.
Plugging the vacuum hose to the EGR valve might also help; however, plug it back in if the engine starts pinging.
Maybe a better timing curve in the distributor.
A better carb couldn’t hurt especially if the carb is original. Probably worn out.
However a lot of things inside the engine can be the problem. For example low compression ratios and very mild camshaft lobes. You’d have to get inside the engine to do things like put in new pistons or shave the heads or replace the cam.
You could start by opening up the air flow. An internal combustion engine can be viewed as an air pump powered by gasoline.
Put a larger, unrestricted exhaust on it for outflow, and headers. A friend has a little Datsun 510 with headers and it does make a difference. A little one, but hey, it’s a little car. Put a cold air induction on the intake for more air coming in.
Then you need more fuel, so you probably want to change to heads with larger valves, and follow up with a better carburetor. And you might want to install a new cam shaft that will take advantage of these mods.
Of course, practical advice would depend upon the actual make and model of car you are thinking of.
I used to build VW bugs in my younger days and we would replace the heads with ones that had over sized valves, replace the vacuum assisted distributor with a centrifugal advance one, a hotter coil for more spark. And of course the beauty of the boxer engine is that we could just buy a complete set of larger pistons and cylinders and swap them out. Turn a 1300cc into a 1800cc.
Where to start. Those old motors had low compression, emissions designed cams and carbs, and restrictive intake/exhaust. You can bolt on all kinds of stuff, it will still be a dog. If you can afford a crate motor thats your best option. If you want to build, you need specialised tools and experience and even with that to duplicate a crate motor will take a lot of time and will have no guarantee. With a crate motor you should recieve just about everything needed with the exception of a set of headers, motor mounts, and some with or without air cleaners. Then you will start blowing transmissions, rear ends, u-joints, etc. A hot rod can be fun, but they are all money pits, and require daily maintenance. (Mine-79 Z-28 )
Thanks for the comments. I’d guessed it wasn’t simple, otherwise ads for those types of cars would all say, “already installed the better carb and muffler.”
BTW, I’m not looking to buy anything, just idle day dreaming about the cars from my youth.
I do the same thing with old bikes. Some of them have great styling, and can be bought running for small amounts of money. Then I start to wonder if it’s possible to put real brakes on them. I’m sure it can be done, but unless there’s a $500 off the shelf kit, it’s probably much better to just buy something modern.
Old bikes need it much less, really. I currently ride a 78 CB400T, which is the exact same bike I started out on back in the day, and I’ve owned more modern bikes. While I’m itching to try an ABS-equipped bike, there’s little I’ve found wanting on the CB400T compared to modern bikes with similar power, aside from the lack of EFI. Perhaps most telling is the Yamaha SR400 runs similar hardware to this day (5 speeds, front disc, drum rear, etc).
You might check out Honda’s CB1100. For 2014, they’re adding a sixth gear. It hearkens back to the CBs of yore and it gives me a mild case of new-bike fever.
To the OP, it really boils down to the answer to the emissions question. If you’re required by law to maintain the OEM emissions equipment, you’re pretty much hamstrung. Otherwise, increase the airflow, increase the compression, and remember the old saying, “There’s no substitute for cubic inches.”
This. The very earliest smog engines had few internal changes and some crap hung on the outside. After that, though, manufacturers completely changed the internals. Without replacing the whole top of the engine, you aren’t going to get any significant power boost.
A carb and intake won’t add much because the heads are low-compression and low-flow. Add heads and you still have a low-compression pistons and a very mild cam with low lift and short duration.
By the time you’ve replaced pistons, cam, heads, intake and carb… you’re in pretty deep and will start running into problems with blocks of that era, and might need a new crankshaft if the original is intended only for a mild engine. Then you need a beefier oil pump and often a better water pump.
Frankly, as long as you are out from under smog checks, you are better off finding a more powerful drop-in engine than wasting money on a smog-era boat anchor. You can likely find a decently-built replacement for any common engine size by watching the auto traders - people build an engine, then pull it for another, or build one and never finish the car.
I had a 1975 Pontiac Grand Am with a 400 ci engine. I went to Norm Day’s Speed Shop, a place with a good reputation. I had them put on an Edelbrock manifold with a big Holley carb on top, and a pair of headers (Hooker? Hedman?) Then I rumbled off to a muffler shop to get the rest of the exhaust done. The power gained was somewhat disappointing.
What I learned: Staying with the 400, I should have gone on to get a new cam to actually use the better breathing.
I also learned that I would have been better served by swapping the 400 for a small block engine, which is simpler and cheaper to hop up. So many small blocks get hopped up that I might have been able to find headers and manifold in a junkyard.
I weep at the uncounted millions that have been spent in such fruitless endeavors.
Besides the cam, the heads were probably restrictive as hell, too. That’s one of the reason that just stripping smog stuff off and knocking out the catalytic converter didn’t add much if any power - the engines were optimized to run with low flow and high backpressure. After the very earliest days of draping crap over an unmodified engine, trying to “remove” smog gear was often counterproductive.
The killer is it can’t be avoided. It’s amazing how many people come on car forums planning to buy the cheapest, lowest-powered model of a car and want to know how to improve performance.
**“I’m buying a Fiat 500 for $15k - how do I get it to be as fast as an Abarth?”
**“Um, just save another five grand and buy an Abarth…”
**“Hey, I didn’t come here for this crap! Tell me what I need to know!!” **
“Okay, okay, sorry! Well, you’ll need an aftermarket turbo kit, professionally tuned, upgraded suspension and brakes, and an upgraded trans to deal with the torque. All that will cost you about $10k, void your warranty, and when you go to sell you’ll get maybe a hundred bucks more than what a stock 500 goes for and nowhere near the resale on a Abarth.” "Thank you! So, should I get the turbo first…?"
:smack:
Ah, yes, the $25,000 Civic. See them all the time, usually waiting for either their $10k paint job or $6k in wheels/tires.
I guess I can understand the process - Mom and Dad help you buy an itty, cheap commuter car and it’s easier to fantasize about turning it into a Fast&Furious contender $200 at a time than to save for something genuinely better. A lot of newer cars, though, do have some performance potential that can be tapped. The “malaise era” cars - and what a great term; I’ve heard it before but relearn it from time to time - are pretty much dead in the water as far a simple upgrades. You’re lucky if you can keep the block, crank and rods.
I remember the letters column in Popular Hot Rodding once had a letter that I paid special attention to, since I happened to own a car just like the letter-writer’s:
Q: What’s the most cost-efficient way to improve the performance of my Plymouth Duster with the 318 V-8 engine?
A: The most cost efficient thing to do is sell it and buy a Duster 340.
