i want to build a 390fe with nitrous, i want to have around 400hp naturally aspirated and about 550hp on the spray. any ideas on what kind of parts id need to keep from blowing the intake through the hood?

 

The key to horse power is compression, compression, compression. Any well built 390 GT engine will be able to handle more horse power than you are talking about. First you should start out with a '68 Mustang or Fairlane GT engine as they will have as good con rods as you need, the pistons will be satisfactory. If you have the buck$ you could go for a set of 428 or 427 rods and a set of forged pistons and full circle rings and a good balance job. Forged pistons will require more piston to wall clearance than the hypertecs. Just be sure you have the crank and rods and rod bolts Magnafluxed before you do any work on the rods. Make sure the rods are sized correctly at both ends and are the same length plus or minus .0005 inch ( just because someone says they are new or remanned dosen't make them, the parts, correct). Check everything at least twice.
If you want to get fancy you could polish the beams of the rods which will help stress relieve them. The sanding and polishing has to be done lengthwise only. If you build it like that you will have a 8,000 rpm engine with the correct cam, lifters and valve springs. Also, for a street engine I would keep the compression at or below 11.5 to 1 unless you are going to run a MSD type of tunable ignition.

 

Just build your basic Edelbrock & forged piston engine. RPM heads & intake, a small solid cam - Comp 282S would be good, forged flat tops for around 9.75:1. Scat rods are cheap insurance - stock crank is fine. You'll be real close to your target - keep top ring gaps up around .020 or better.

Don't polish stock rods - just makes weak parts shiny and adds no strength. Ask how I know this....

 

Thanks. i already have a 390gt block and crank to use. what kind of heads should i use? i dont want to spend the money for aluminum heads or ruin rare 428cj stuff with porting. whats the best alternative?

 

The GT crank, and block are identical to those of any other 390 - no difference at all in any way. But they'll do the job. Pretty much any FE casting will handle your needs modified with a 2.09 intake, a very good valve job and some hand porting. The odds are very much against fining any valuable castings in the core pile these days - the CJ heads are C8OE-N.

 

If your going to run a nitrous system...I would suggest useing a RPM window switch..& a good air fuel gauge.....As long as you dont spray below 3000 RPM or run lean you should be OK....so they say...Lew

 

what are the best ways to know (gauge or signs) if the engine is running lean and endanger of melting pistons?

 

Its allways good to pull the plugs after a run to take a look ...We use a dash mount fuel pressure gauge to moniter the fuel press..& a LC1 wideband gauge to moniter the air fuel ...So you can see if you have a lean condition,,,..Lew

 

thanks im gonna use my currently stock 390( will have cam, intake, headers) as the test to see how everything works out before i build a motor so i dont ruin a good motor that has a lot of money in it with experimenting..