Forced Induction Question's

[Koz-04Mach]

Few questions I am hoping yall can answer.

Why is it recommended to stay between 6-8 lbs of boost. Is that the max boost that can safely be ran, or is that due to the HP range that amount of boost puts you in? For example is a car running N/A at 300 hp + 6-8 lbs of boost just as safe as a car running N/A 400 +6-8 lbs of boost? Also, how do different cams take a play into it? Do cams made specifically for forced induction allow you to make more boost or hp safely, or what exactly are the cams doing that are made for different applications rather then using stock cams. An easier way to ask it is, do our motors have a cap level of hp that is safe to run overall no matter how you get there?

[Lonestar 7]

Its your lower end that keeps safe boost max at 8 psi. So you go forged and you can up the boost.

[Koz-04Mach]

But is it the boost, or the hp that boost creates that is the problem? If bob has a bone stock Mach-1 and slaps on an 8 lb blower, and I have 430 hp and slap on a 8lb blower. Will my bottom end hold up just as well? I agree with you the lower end is the weak link, I just dont grasp what about the blower hurts the lower end, boost or total hp.

[ITS BACK]

Step up .

To simply answer your question, yes, the boost is the problem.

If you want a more in depth answer read on.

The problem is how much pressure that is being applied to the piston, which as you know gets transfered through the rod to the crank. The type of pistons that are used in our cars are work really well with a N/A motor but with the extra heat and pressure from boost or nitrous they are not the best choice. The real trouble maker is our rods though. The powdered rods are designed for N/A motors too and will break if any thing goes wrong under the higher boost.

The amount boost that is safe for a given rod is detemined buy the way that the rods are made ie. powered metal (like ours), forged, or billet. The design of the rod also plays a role in the equation too. The forged H beams are stronger than a forged I beam rod. However the billet rods which use the I beam design are stronger than the forged H beams. Did that make any sense?

The design of the piston also has a major role. The stock pistons are a "flat top" piston meaning exactly what it says the tops are flat. A dished piston has a portion of the top of the piston cut away in order to lower the compression ratio to a safe level for boost.

Example:

My near stock Mach makes about 305 rwhp at stock 10.1:1 compression. The guy I bought me turbos from has bullit rods and 17cc dished pistons. These pistons lowered his compression to 8.5:1. Last December I had ran him on the highway and we ran pretty much even. *NOTE* he was N/A at the time. So because of the lighter weight bottom end he had the same power N/A as I do. The difference comes in the amount of boost we can run. Right now with the stock bottom I would only feel "safe" running 6 psi, which would be about 450(ish) rwhp. He on the other hand had been able to run 28 psi with over 1000 rwhp, while he had the turbos on.

If you understood that great because I confused myself and had to re-read it! LOL

IMHO there is no "safe" amount of boost that can be ran on the stock Mach engine. If anything is off on the tune that will cause a problem eventually.

step down .

If anyone sees something wrong in this post, please post what is incorrect so it does not cause even more confusion.

[loathe]

thanx for the info ITS BACK

[340.29m/s]

I would have to say HP. If you are already pushing 400 RWHP and then put a blower on to take you to 575 or more... it's gonna break. Even if you are only at 6PSI.

The boost is not the problem, HP/Heat/Wear is what will get you.

(Remember, boost is just a measure of resistence.... not how much air is actually flowing)

[Koz-04Mach]

Thanks for all the replys. I think 340 got what I was shooting for question wise.