I knew I would catch some flak from writing about performance and the 300I6. It's a great motor and I really like it in my van for what it does. I guess what I am trying to get across is there really are better motors for set you back in the seat acceleration and over all performance, if that is what you are after. If you do not go along with that statment, you are lieing to yourself. It's fine to want to get more performance out of any motor, but to say the 300 I6 is the best place to start?........ Want to see a movie about a under dog engine builder? See "The Worlds Fastest Indian". It came out last year.

 

yeah i understand completely. i too suffer from the same dilemma as you. i wish you the best of luck, lemme now how it goes. i could use the help.
jjsimms

 

Gee, 7 SEVEN main bearings easy to get 8,000 rpm. Smooth running, strong enough to be boosted to 500 HP TONS of torque. What do you want for performance a Saturn 5 Moon rocket booster?

 

You aren't going to spin a 300 to 8000 rpm without a ton of cash outlay. Custom crank, rods, pistons, etc. Even with all of that the block will probably come apart. How are you going to feed this thing at 8000 rpm?

 

The best performance mod that I have done with my truck was removing the brokeback grill guard and fake hood scoops and doing the lift, gears, and tires

 

For valve train there is crane/compcams/isky/clifford, others but i cant remember and you can always go with a custom grind. For the people that say that you can not get high HP out of a 300 you are wrong!!!!!!!. In terms of the efi 300 the 5L and 5.8L efi throttle bodies bolt up but to the intake but you have to port the intake, the v8 throttle bodies ports are 10mm bigger than the 300 tb (if i mesured correctly). In terms of tuning the efi I would look for the 96 mass air computer and wireing because it is OBD 2 and the SCT tuner will tune it for bigger injectors, cam, mass air and even for boost and nitrous. For headers there is hooker/headman/cliff/and others but i cant remember.The hooker super comp headers are a higher rpm header because they have large primery tubes, the headnam headers have very small primery tubes making them a good low rpm header, the cliff headers primery tubes are in the middle of both of these headers. I own all three of these and they are all long tube headers with dual outs. I suggest that you go with the headman or clifford headers if you are not planing on climbing the rpm range to high, and dual 2 1/4 inch exhaust or if you want higher rpm's go with dual 2 1/2inch or dual 2 1/2 inch off the headers into a big single 3 inch, muffler and exhaust. Thats what I am runing.(but you loose low rpm power if you do not have the stuff to fill that big exhaust!!!!)

 

Kind of off topic but does anyone know of any shorty type headers for the 4.9 that bolt up to the stock exhaust? And if I get a salvaged intake and TB and mess around with porting it and such, then put it on and the computer freaks out, can I put the stock stuff back on and everything be ok?

 

clifford part number 53-0016 street rod headers efi, but they don't bolt up to the stock exhaust and they look like they might not fit trucks.
Yes every thing will be ok, the computer should not FREAK OUT by changing the TB, but you have to make sure the TPS(throttle position sensor) is at the wright voltage, 0.88-0.93 must not go over.I would also swap over the IAC(idle air control valve) to the bigger TB. Make sure the TB has the same TPS plug on it and some V8 TB'S have coolant runing threw them, not a big deal!

 

Are the IAC and TPS the same on both TB's? Or did they use different ones for V8s?

 

Sorry I forgot to say that some of the newer TB's don't even have a IAC on them and the TPS plug will also be different. You have to find out if your TB has a IAC on it and what kind of TPS it has so you can match it with a V8 TB. If your TB has a IAC on it you can put it on a V8 TB that came with an IAC. You can also swap the TPS as well. You mite have to swap the throttle linkage off the v8 TB with the linkage off your TB if it is different. (it is easy to swap all this stuff, the harder part is to port the intake)

 

Unless you've gotten the head to flow better, a larger throttlebody won't gain you anything. The big air restriction is the efi head not the TB. Even then you won't get a power gain, without going to larger injectors and a longer duration cam, but might get an improved throttle response. Not saying to not do it, just be aware of when it's needed.

Swapping from EEC-IV SD/MFI to EEC-V MAF/SFI is not a simple matter. It requires some sensors that aren't present in the speed density system. Like misfire sensor (IIRC a different harmonic balancer is required for this), Mass Air Flow sensor and supporting air ducting, and a total of 3 HEGO's for starters. Not to mention the OBD-II port that is needed in the cab. While your at it better get the complete engine harness from the donor because the EEC-IV and ECC-V computer plugs are not compatable. (60 pin vs 104 pin) Again, not saying don't do it, but be aware of what it's going to take.

Another option is to swap from the EEC-IV SD/MFI to EEC-IV MAF/SFI that was available in California (and New York?) in 95. Just need the MAF Sensor and wiring, Overlay for additional injector wiring, and 2 HEGO's configured for front/back bank sensing. Custom tuning should still be available for performance changes. Not easy, due to few computers being available since it was only offered one year, but possible.

Another one is to use a V8 computer and custom tuning to let it run a 300/4.9.

Overall though getting some performance gains can be done a lot less expensively. A freeflowing single 2 1/2" exaust with a clean HEGO, freeflowing filter in the stock airbox, and a hotter coil with a TFI the extends the charge dwell and plugs gapped to take advantage of the hotter spark. These things will net measurable hp and torque gains. At the vary least match the hp rating of the 88 EFI 302 but with superior torque. If you have a friendly exaust shop and are willing to stick with galvanized pipes instead of stainless you should be able to keep your costs under $500 and still be able to use 87 octane. You spend that much on the SCT w/custom programming put need 91 octane or better because of the timing advance.

Something to think about.

 

The stock TB on my 96 MAF/EFI was a flow restriction. With the stock TB, there was vac in the plenum chamber above 4000 rpm at wot.The Larger TB (96 5.0) helped my truck Quite a bit. I removed the intake plenum and bored out in the area from the TB mounting boss into the plenum chamber in a bridgeport machine to 1.900" inside dia. I then taper bored the area from the TB exit into the plenun from 2.060" at the opening to the 1.900 diameter of the plenum bores. An adapter was bolted to the MAF at the same time to add a K&N filter and the IAT sensor. After the mods, My truck would now pull my enclosed 20 foot trailer better. Before the mods It had a top speed of around 65 mph on flat ground in 5th gear, after mods 75 MPH is easy with less throttle imput. I later installed 2 1/4 duals with an X pipe and 3 chamber flowmasters. The exaust seemed to help the power some, with a gain in MPG while towing.

 

As Dr. Evil would say, "riiiiiiiight...."

Seriously though, how do you figure?

 

8,000rpm does seem a little ridiculous. anyway i think that might kill dependability. what good is a performance motor if you have to rebuild it after every run.

 

Hmmm. Let's think this one out. The power peaks at 3400 rpm, so let's concern ourselves with what's happening in the intake at over 4000. IIRC, I got 2"Hg vacuum in my intake at 4200 rpm. Hardly enough to make any difference.