Tips, Tricks and Performance Upgrades for engines with EFI
 

This thread will be for Performance Upgrades and or Tips and Tricks to adding more power to your Inline Six EFI engines. :-D

Sorry about some of the posts from the past that were lost but there was no way to go through them all and separate the carb tips from the EFI tips. Many people have asked that there be a sticky for both types of fuel delivery methods, so I have figured the easiest way is to start fresh.

Please post only Performance Upgrades or Tips and Tricks for the inline sixes. All other posts will be removed. We want to keep this informative, easy to look through and straight to the point. No questions, conversations or general talk will be allowed. If you see things you want to know more about then PM or Email the person whom posted. :-tap

Thanks for your help on this and together we should be able to make a great Performance Sticky. :-X22

Here is a good post on performance for the 4.9 EFI. Thanks "Motorhead351" for your tips. :-X22

Lets start with a few simple, cheap and realitivly easy mods. This section will cover the exhaust portion...

Exhaust:
Opening up the exhaust on a stock 300 is one of the better ways to increase performance. after choosing a muffler of ur choice (the exhaust sound will be covered later) u should decide how u want the exhaust done. weather it be duals out the back, right after the rear tires, lightning style or whatever keep in mind that exhaust size should not be more than 2 1/2 inches for a stock or near stock 300.

For a dual exhaust set up 2-2 1/4 inch set ups work fine. running true duals will not add any more power but will make for a terrible sounding exhaust. adding a crossover in the system allivates this to a degree but a single exhaust is best.

Next biggest question is if one can remove the cat(s). the answer in short is, no (see below). removing the second cat is acceptible because there is still one on the vehicle. this needs to remain there because it acts at the down pipe for both of the EFI manifolds.

U can remove if u replace them with a high flow unit, but one must remain on the vehicle. Walker offers a downpipe for the EFI manifolds (part number will be added soon) for a bolt on affair.

Next is should i purchase a set of headers...and who makes them for my truck. this is a good mod to add but is not nesseccary. the stock EFI manifolds are a cast manifold that mimic a shorty header. they flow very well for stock but are known to crack.

There are only a handful of shorty style headers that are an almost direct fit offered by clifford but the quality has been lacking lately. on the other hand there are a lot of long tube applications avaible. long tubes are better for the 300 because they help the low end torque and really flatten the torque curve. manufactors are, but not limited to Hooker, Hedmen, DynoMax, Pacesetter and a few others. dont be fooled if they do not offer a header for ur application, all 1987-1995 trucks are the same weather its 2wd or 4wd. the exhaust is on the passenger side and the 4wd hardware is on the right so that is not an issue. also crossmembers are close to identical on both so they will fit. there may be starter clearence issues on some vehicles and the need for a starter heat shield may be needed. also starter access will slightly more difficult.

As for the install, well this can be a little tricky. They do require some modifications to be made. one area that has been know to cause interference is the altenater bracket. is has been known that it needs to be trimmed slightly to clear the first header primary. in some applications it will also be needed to be spaced out a little from the block. other issues are the EGR valve, which will require a custom mount to hook it up or a jumper resistor from fordfuelinjection.com.

Muffler preference, this really depends on what u like. please remember the 300 will never sound like a v-8. i suggest checking out exhaustsoundclips.com and checking out the various 300 set ups. my personal suggestion is magnaflow...with some nice, big tips.

No problem optikal, I just wanted it to be clear you CAN remove the cat(s) or to be politically correct, not replace when they rot off or for offroad use only, if emissions are of no concern and you have an SD vehicle. With a mass air vehicle, potentially a stimulator could be put in place of the second O2, like other makes/models but that is speculation on my part.

When you state:






Being a technical thread of sorts, one might walk away with the impression, it can't be done for technical reasons involving engine function. Know what I mean? Nice write up on exhaust though.

If anyone wants to convert the pedastel mount head to adjustable rockers using 3/8" stud, bolt in deal, Crane part number 36655-16

This would allow the use of chevy inline six 250/292 rockers which have a 1.7 ratio vs the fords 1.6

For those wanting the ability to program their 4.9, heres a thought:

As found in this thread:

https://www.ford-trucks.com/forums/s...d.php?t=250890

would those still clear the factory valve cover? thanks

Actually, the poly lock would probably hit the valve cover.

There are fixes for this, clifford performance sells a spacer for the upper and lower intake, along with their taller valve cover.

Some had success with shorter poly locks but I don't have the part number.

You could also do what silver streak has done:

https://www.ford-trucks.com/forums/s...hlight=rockers

I think many get to this point and say screw it and get a cam with the lift they are after, utilizing the stock rocker arms.

These are the entries that I had to change on the BIO0 351W computer to run a 6 cylinder.

Scalars
Engine displacement - change to 0.172389
Number of crank degrees per pip - change to 120
Number of cylinders - change to 6
Number of cyl/2 - change to 3

Table
Firing order - change to 1 5 3 6 2 4 0 0

There will, of course, be other things that need changing like the fuel maps, timing maps, mass air transfer, etc. The things I listed above should get it running. Mike Glover, the creator of Tweecer, gave me the info.

The BIO0 computer is supported by TwEECer so it can be tuned. The other option is a '96 eec system that is tuned by the SCT tuner.

If you like an auto tranny and don't mind the lack of an Overdrive, then keep the C6.

The 300 can make plenty HP/TQ, whats your target HP/TQ and at what rpms?

FWIW

Arias and Ross do custom pistons, expect to pay for their services. :)

Port/polish allows any cylinder heads to flow better, if done correctly, the stock head is no where near ideal.

The only consideration, in regards to the efi head, is the combustion chamber shape and valve size. In stock form its pretty tight or shrouded as compared to a carbed head, due to the heart shape. With that in mind, most would recommend that you stay with a stock valve size, for a small cc port on a street engine, this isn't a bad idea anyway, larger valves aren't always ideal or required, just an easy way to increase the cfm flow (in many cases).

Heres the kicker, the effects of larger valves on an efi head is pure theory, as even the resident experts on this and the other inline forum have not to my knowledge, actually flowed the head to be able to say with certainty the effects, be it positive or negative as compared to larger valves in a carb head. You'll get the usual don't do it, its shrouded in stock form, then get another that says he installed larger valves and it pulls like a freight train to 6000 rpm, which a dirt track racer, did make this comment, on the other "inline forum". :) Another will tell you not to lay back the combustion chamber because this will effect the swirl of the incoming fuel/air mixture and negatively affect the efficiency of the combustion, as with the swirl you can get away with less timing. Again, honestly the effects are unknown and this is again, theory. If it did effect the "swirl" negatively and your modifying the engine anyway, then I am sure timing would be added via a piggyback chip once the engine were dyno tuned, so does it really matter?

You be the judge. :)

You have a few options with the efi head.

Go with a 1.94 valve and try and move the combustion chamber wall back, as to unshroud as much as possible, yet retain the "swirl" effect of the design.

Take a 1.94 valve and have it turned down to something between 1.94 and 1.78 (stock) to try and get a little more flow, while keeping the shrouding down.

Last, have a porter thats worth a darn, try and get as much flow as possibly using the stock valves.



Honestly, if your still considering the megasquirt, you may wanna go ahead and get a carb head, then you can add the larger valves for "maximum" flow potential and add timing as needed. If your gonna keep the stock computer then the carb head may not be a good idea, as the carb head likes more timing than the stock computer is designed to give.


Its really your call, theres no "right" answer, other than to say, port work to the stock head be it efi or carb, if done right, is a good idea.

This weekend I cut one of the cats out of my exhaust (the one farthest back) and replaced the stock muffler with a high flowing glasspack. You really can tell a difference guys. Not as far as lowend tourqe though. But now I can hold gears going up hills and I can pass alot better. So more like higher RPM stuff. As far as mpg I can't really tell yet, but it seems the same. My exhaust runs out the right side behind the cab into a big 4" tip I added. It's also a little louder now with this muffler, yet not open pipe loud. I would RECOMEND this to anyone looking for a lil more guts for their ride.