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what to do to upgrade the 300 straight six

34K views 19 replies 15 participants last post by  HarryGnuts 
#1 ·
what would be the best decicsion as far as intake,carb,cam, and lifters. im looking for better performance and hp. also whats a good sounding exhaust to pair with the 300?
 
#2 ·
The best option i would have to go with very first i mean top on the list would be going to the top of the page and putting in "straight 6 upgrades" or " 300 upgrades" or how ever you want to in the box next to search ,then click on search, and BAM!! A wonderful world full of answers...just sayin...
 
#8 ·
...just lookin for advice
Maintain it - nothing else. Mine has about half a million miles on it (really), and I'm putting it into its 3rd chassis so I can keep flogging it. The first was wrecked so hard the engine ripped off the mounts & broke every accessory off the block; the 2nd got rolled, then driven for over a decade at ludicrous speeds on- & off-road. This time, I'm not gonna go easy on it. ;)
 
#7 ·
#12 ·
For the EFI 4.9L 300's, there's really not a whole lot you can add to it that it doesn't already have. Crane and 1 other company(can't recall now) makes a computer compatible cam for it. Other than that, you're pretty much done. You can put in a 2.5" exhaust which is a minor upgrade from the 2.25 that's in it already. I did the 6Litre tune up and noticed nothing different. I replaced the rusted out factory exhaust with a full header back 2.5" unit and noticed no difference either. Mine is a '92 EFI engine that was very well maintained by the previous owner so if there was going to be any changes from what I've read that would gained me anything, so far they haven't worked.

Over on Ford six, you can find people who put in $1000's of dollars in order to get serious HP/Tq. It's only worth it if you truly love the 300's like some of us do. You could easily spend much less on a V8 to get more power.
 
#13 ·
Over on Ford six, you can find people who put in $1000's of dollars in order to get serious HP/Tq. It's only worth it if you truly love the 300's like some of us do. You could easily spend much less on a V8 to get more power.
i love my 300, but for that amount of cash, why not go from a inline six gas to a diesel 5.9?
 
#16 · (Edited)
The 300 is a great engine in stock form, but there ARE performance parts for it.

However, 90% of them are for the carb'd engine. The fuel injected computer doesn't take too well to mods.

The 300's biggest issue is its inability to breath. The carb'd model especially. The carb, intake, head, and exhaust manifold was simply too restrictive for the amount of cubic inches the engine is.

For my 300, I have exhaust manifolds from a fuel injected 4.9, which is a great upgrade and flow way better than stock. There are also headers available, but they're significantly more expensive, and come with problems of their own. For a mildly built 300, the EFI manifolds are where it's at. Pair that with a 2.5" exhaust out the back. I have a turbo muffler on mine and really like it.

The 1bbl carb is also much too small. It's only about 190cfm, which doesn't let the engine rev much above 3000 RPMs. Clifford performance and offenhauser both make 4bbl intakes for the 300 that'll let you put on a nearly infinite range of carbs. A well tuned 4bbl should be able to get you way more power, plus nearly the same gas mileage as the stock 1bbl. Mine has WAAAY more power than stock, and I get 17 - 19 on the interstate and around 14 around town.


Just an intake/carb and exhaust is going to really wake that motor right up. But, if you want to take it further, port and polish the head to really let it breath. Then, you can pick a cam of your choice (a 260h is a common choice). Installing larger valves into the head will do a lot for it as well.
 
#17 ·
Since none of these dang idiots seem to be getting the clue that you want to upgrade your engine I will tell you a few parts that I know of personally that work. I would put a 4 barrel carburetor and an intake manifold that can hold the carburator. Then I would put a new exhaust system that would be a little bit bigger than the original. If I was you I would also look into getting a performance intake system like a cone cloth filter and maybe some piping that goes farther out to make the air filter go toward the wheel well. If you really want to you can put a turbo on it but I wouldn't because that way you can wear parts out fast, but if you're going to go the turbo route then you probably would want to add an oil cooler, a new more advanced radiator, and you are going to have to redo the timing. There are a lot of things that you can do to the 300 but it depends on if you have the money, time, and are willing to take a risk. I would probably do everything but the turbo. Also if you are going for hp and not torque then adding a bigger exhaust pipe or going straight pipe will help, but I would personally go for more torque.
 
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