I noticed a few of you guys have built up your own 300. I've wanted to for a while now, but I have noticed that everyone has built a carburated engine. I have an '89 EFI and was curious if anyone has built an EFI to get some more horse out of it. I'm not looking to get 500 hp out of it (although that would be cool) but i need a rebuild soon and figured I would put in some performance parts as I build it. Anyone build an EFI that can help me out?

 

check out my thread "what have u done to ur BB6" and read the stickey at the top of the forum...

 

If I could look at the sticky I would, but there isn't one on my computer. If someone could give me the link that might work. And also I guess my main question was has anyone built up an EFI like your carburated I6's and if not is there a reason you guys haven't done so?

 

well ill be damned, there gone!

 

They're not gone, just cycled through with the rest of the threads. Do a search and you'll eventually find them. It's been about 2 weeks since they started on the normal cycle.

 

Hey thanks for posting those threads again, they have some good info. I guess my main question was: is there a reason why most people on this site seem to have built the carburated I6's rather than the EFI's?

 

Main reason most go with carburated 300's is because there is no aftermarket support for the EFI 300's. The limiting factor in the EFI is the computer. You can't do alot of modifications without the computer acting up. Almost all EFI 300's came with speed density which isn't all that friendly to changes. Also there is a little more in the aftermarket in terms of carbed 300's. There are a few different choices on intakes. You can run a bigger cam without having a computer in the mix too. Those are the main reasons. I also have a fairly mild built up carbed 300 in my 82 F100.

 

So if I decided to build a carbed 300 and drop it into my '89 how would I get around the ECU for the EFI?

Would it be do-able if I did a mild build on an EFI and put on headers, new exhaust, a cam, maybe a chip, and other various parts that go along with using performance parts? About how much hp would I gain by using these parts?

Thanks for the tips guys, it helps me out a lot. I'm a newbie when it comes to this stuff.

 

Don't let EFI stop your build. You can do plenty with the stock computer. As long as you keep the cam within reason it will react fine.

 

If I may be so bold, You might want to concider just tweeking things. The I6 isent about high horse power. It is the torque at low rpm's ware the 300 shines. Things like mild cam Balenced rotating asemblys free flowing exaust will all help. Lighter rocker's to free up a few ponies is also a good choice. Cehck out cliffrod 6=8.com thees guys have some cool things for I6's.

jbot

 

There are some simple things that can be done without rebuilding to free some power.

• Replace the dual cats with a single high flow cat.
• make sure that the HEGO is clean (replace if unsure and high miles)
• Pull the combination manifold and clean all casting flash from inside the runners and polish.
• Upgrade to a hotter coil (45K or better) with matching TFI module and open spark gap to .055
• Improve intake airflow. At a minimum replace restrictive paper element with a higher flowing element, something like the K&N direct replacement is a start.
• Basic tuneup items like fixing vacuum leaks, clean the EGR.

Some of these things are more expensive than others, but together should net 5-10% gains on a dyno.

Once your into a rebuild then your limiter is budget and availability of someone knowledgable in tweeking the computers control tables. Even our speed density engines can be modified to handle hotter cams, it's a matter of knowhow. Granted the MAF systems are easier, just rare in the 300/4.9 EFI's.

 

ok since no one is really giving hard core answers ill chime in.

i chat with my two buddies who have significantly built EFI 300s (cam, head work, larger injectors, etc...) but neither run headers. anyway, they say driveability suffers a little with the larger injectors/adjustable fuel pressure regulator and the stock computer program. so i would say a piggyback chip would clean up that. other wise they said the headwork and cam havent hindered the computer at all.

remember, the speed density system relies on MAP (essentually manifold vacuum) instead of the mass air flows incoming amount of air. so if u choose a cam that is realitivly close to stock duration and lobe seperation u should be ok. i and one of my friends chose the Crane powermax cam (see sig) while the other chose a cam almost identical. neither of us have experience any issues with the ECU. they also did/had mild headwork done (no extensive port work, just a mild clean up of the bowls and gasket matching) and the computer has adjusted to the mods fine.

both of the cams used were a dual pattern, and that seems to be key with the 300. since the exhaust flows so poorly, the dual pattern cam can be taylored to help the ehxuast side out without getting to radical on the intake. also on DD2K, the cams we used showed the best power increase in the 300s natural power band, while extending it several hundred rpm but keeping the same basic curves.

now im just running the crane cam but i chose headers instead of getting into the headwork right now, and i do not have larger injectors. still no ill effects besides a dam CEL for the EGR (may or may not be header related, i did essentially remove the EGR LOL).

what i would honestly do, is get the truck on a dyno and check the A/F ratios to make sure they are running close to Stochiometric, that would warrent the use of larger injectors or not. but the ECU doesnt seem to mind mild head work, mild cam or headers.

the bottem line though, is that there are aftermarket intakes and such for the carbs and it is easier to tune than EFI. but if u keep things within reason, there is no reason u cant build an EFI 300. now if u get into radical grind cams, hog out the ports and all the computer will go FUBAR LOL...

 

I have been told that the stock EFI workd great with a Megasquirt controller. Thats what I plan on using. Plus they won't break the bank.