My 351 is getting old and I was thinking of boring it out and adding a supercharger to the next rebuild/new engine.

Is it worth it to bore it out to 392? What kind of performance can I get out of this?

I'm going to super charge it, chip it and run performance cams/pistons and valves.

Anyone have any suggestions/comments to an engine this size?

Thanks,

Pete

 

You can't bore it to 392, that takes a stroker crank (3.90" stroke vs. the stock 3.50" or a 3.85" stroke plus a .030" overbore)

How much power? How many pounds of boost are you going to run?

Is it worth it? Only you can answer that question.

 

If your gonna put a blower on it, build a 357 (standard crank with a .030 overbore.) The stock crank is fine as well as the rods. But forged pistons are a must.
If your is mass-air equipped any cam will work, just chosing a good blower cam a bit of a trick. If its speed density your rather limited on cam selection. Your best bet is to call Terry at cam Motion. He can grind a custom cam for you that will work great for your application.

As far as the blower, it all depends on how fast you want to go or what kind of power your looking to make. If you want lots of low end torque a Kenne bell is the ticket. For all around performance a Vortech, Powerdyne, or Paxton Novi 2000. Im a big fan of the Novi, but the Powerdyne is a good blower to get you running better.

 

cool thanks for the help. Yeah it is a speed density and I want to run as much boost as the engine can safly handle (can you tell I don't know much about this, but I am learning) I was looking at the powerdyne kit. That one looked good to me. I'll look into the Novi though.

Why do you suggest a 357?

Thanks,

Pete

 

I want my truck to sound like american muscle if you know what I mean. I want aggressive cams.

Pete

 

if you are going to put on a suprecharger, you will need to lower your compression ratio a little, otherwise you will get detnation. If you are serious about it, I would also convert to a mass air set up. Ford motorsport maker a kit for it that works really well. what you want is going to be expensive to build and expensive to maintain. Another route that you could go is a stroked engine with higher compression and just forget supercharging. Again I would reccomend a mass air conversion.

 

Agressive cams and superchargers are not compatible technologies, at least not on the street. High duration cams have a lot of overlap. superchargers hate big overlaps. A lot of your boost gets blown straight out the exhaust without making much increase in power untill you start to turn mega RPM. At low to medium revs it will be a stone and have major drivability issues. What you need is a fairly mild cam with lots of lift and not much increase in duration with wide lobe center angles. A dual pattern cam with increased exhaust lift/duration is probably a good idea. It won't sould real radical but it will run like the proverbial raped ape. Do you want to sound fast or be fast?

 

I want to be both. I can't decided between building a larger performance engine, or doing the supercharger. Either way it costs a lot, but I think maybe doing something like a stroked engine may be better.

Why is mass air flow better?


Pete

 

It's not "better" it's different. Speed density systems look at manifold absolute pressure (MAP) intake air temperature (IAT), engine RPM, throttle position and some other parameters and look up correct values for EFI pulse rate and spark advance in built-in tables and adjust asccordingly with the feedback from the O2 sensors used to fine-tune the settings. If you modify the engine to the point where the values are too far outside the expected ranges, the PCM gets confused and drivability problems result.

MAF systems measue the aiflow directly and compensate accordingly. They are inherently more flexible and more tolerant of modifications. On a dead stock engine a S/D system will frequently produce more power than MAF because they can be tuned more tightly to the known parameters.

With the level of modification you are looking at, you're probably going to be getting into re-programming your PCM anyway so the conversion to MAF may not be necessary.

Remember the Gen I Lightnings were all S/D. A lot of them have had blowers added without any great disruption in control.

 

I would just stroke it out to 408. With good heads, cam and high compression pistons you can get up over 500hp. The heads will make the biggest difference.

-Jon

 

First and foremost, you MUST determine a baseline for this engine. Were do you want to go with this thing? Budget? Emission legal or not? Time? Used for towing? Is this meant for a drag strip or just some hot street action?

A 393/408 windsor can produce power levels above 500HP and 500 ft/lbs at 5500rpm all naturally aspirated and in a daily driven setup running off of pump gas! The same goes for a stock 351 with a supercharger. Really though, the sky is the limit. If you want 800 HP and still want it to start when its 40 below zero just to drive down to the office, it can be done, but all in terms of $$$$.

 

I say forget drivability, go for 1500hp and rebuild it every couple weeks

-Jon

 

At what HP point does the asphalt separate and fly through the air like loose mud?

 

go with a 357 and run a Pro-charger or turbo with an intercooler. I have a SN2000 and I am getting ready to add an intercooler for the hot days of towing

 

I second the turbo...I'm not sure if someone makes a kit for these trucks, but you could make one yourself for less than it would cost you to buy a supercharger. If you have any welding skills, or know someone who does, this is the way to go.