I’m sending this to you because of your experience with the 4.6l engines. I am building a replacement engine for my truck and already have a complete short block and some PI heads. After long thought, I have come to the conclusion I just won’t be happy until I bolt a blower on this thing so I may as well plan and build the engine accordingly.
My question is this:
I am going to put forged pistons and rods into the short block to get it ready for the blower. I don’t think I will need a crank since the stock one is pretty strong and I doubt this engine will ever end up in the HP or RPM range beyond the capability of the stock crank (insert your opinion here).
What should my CR (compression ratio) be for use with the blower? I have followed some other post of people bolting blowers onto stock engines and needing to add water injection to cure detonation. I don’t want to have to do this. I will pretty much have my choice of pistons so can order the correct ones for just about any CR.

It will be a while before I am finished but will probably contact you since I want a complete blower system and some tuning. I am in the Maryland area but have family in Houston so perhaps I can combine pleasure with pleasure when I am ready for the install and tune.

I appreciate any advice you can give me since this is the next step in the build.

Thanks

WLF

 

I know you can't discuss pricing here but if you can e-mail me the price of the internal kit and what is included with the kit I would appreciate it. Perhaps we will be doing business sooner then I expected.

 

I think 8.0:1 is good for gasoline supercharged applications. I think Lightnings are 8.4:1. In my opinion, the higher you go in compression with any type of boost, the harder it is to not detonate. I hear the Kenne Bell's are have detonation problems. I think part of the problem is starting with a higher static compression. I really wanted to buy a Kenne Bell, but I did not like the idea of detonation problems. Now, this is only what I hear. I do not actually know anyone with a Kenne Bell. I think a lower compression would tremendously help this. I feel that with a lower compression and a little more supercharger overdrive you could actually make more overall torque and power. I just looked in a '03 F 150 brochure, but I could not find anything but torque and power numbers for normally asperated engines. I am curious about another thing. Having built a "new" shortblock, is there a reason you stuck with 4.6 for displacement. Was it a cost factor? This is not intended as a slam, I am just wondering your reasons. I personally am a fan of larger displacements. But often there are many other factors influencing ones decisions. For example I recently bought a Lightning crate engine for my F150. But I did not do my homework and am only now finding out how much more there is to this "simple" engien swap. Maybe htere is more than meets the eye doing a simple 4.6/5.4 swap. The things I can think of are intake, front cover, throttle body, and cam drive (chains). Add this all up and I know it is not cheap. But on the other hand, a blower is not cheap either. And obviously gas milage is not a concern. Again these are just my opinions.
Darin

 

Lower static compression will, of course, reduce the tendancy for detonation but there is a tradeoff.

Lower static complession substantially reduces off idle power and response.

IMHO 8.5:1 would probably be the best choice for a street application, just make sure you buy a kit with an intercooler.

 

Just my .02......

Blowers change the volumetric efficiecy of an engine, obviously. In effect by putting a blower on you are creating an engine with a variable compression ratio. Though the actual ratio in technical terms stays the same, the amount of mixture you are compressing varies greatly.

If you never plan to bump to higher boost levels, you can get away with a higher static compression ratio. The more boost you plan to see the better off you are lowering the static compression ratio.

 

I am not interested in track racing. Also, I pull a trailer during camping season.
I will probably be installing the Magnacharger kit just because of its drivability and low-end torque. I also will probably use the stock pulleys. Should I stay at the 8.5:1 CR or can I get away with higher like Crash's 9.1:1? I don't think it will be modded up enough to worry about having to drop to 8.0:1. Also, drivability is an issue with me.
I am having a stage 1 port and polish done to the heads with good stainless valves. I will also use shorty headers, high flow cats and probably convert to duel exhaust.
The only other changes I am planning are the modifications to the fuel delivery system needed to keep up with the charger and Superchip re-burn to coincide with the charger install.

 

WLF,

I hope you keep us updated on this process. It will make for a very informative thread!

The stock Magna 5 lb. boost pulley will work great with your set-up. If you plan on eventually going to higher boost (and you will), it will also work fine with the 9 lb. boost pulley. However, my prototype Magna "bazooka boost pulley" (11-12 lbs. of boost) is still in the testing phase. I do plan on building a forged internal engine soon and am very interested in the results of your stage 1 head job work.

 

iron horse,
We were both following the PI Head debate. As you can see I decided to keep mine. That also works into the use of the Magnacharger given I still need an intake. I want this engine to be strong and last so I guess I better consider the 8.5:1 since knowing how I am, I probably will want a 9 lb pully later.
Are you using your charger on a stock block? If so, any detonation problems?
I will keep you informed but expect this to be a long process. I am allowing myself the amount of a truck payment each month since I am now not making payments but it will still be a while before it is done.

 

Yes, currently, my 99' 4.6 engine is totally stock with 75,000 miles.

At stock 5 lbs of boost, no detonation or any concerns. Very reliable. Then I put the bazooka pulley on the first time. Up to 9 lbs of boost, no detonation (I also had no stock or tuned chip). With no chip and stock parts I had detonation around 9.5 to 11 lbs of boost depending on how hard I "got on it.

I am waiting on a tuned black diablo two program chip. Then I will re-install the bazooka boost pulley (11-12 lbs of boost) and install 42lb. injectors and a 90 MAF.

Then, I plan on AT LEAST having forged internals. My goal is to somehow get 500 hp/tq. of reliable power at the wheels. I too, would prefer to have lower compression like signmaster discusses. I think the higher the boost the lower the compression level needed.

If I remember, you have installed lower gears than 4:10? You will be roasting your tires !!!!

 

Thanks Crash. I now have direction...