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Hey guys,

I've been reading threads on this website related to supercharging engines for the past year or so and just wanted to straighten a few things out as I start to think more seriously about supercharging my baby (aiming for 450hp with sqidd's gt500 set-up).

First of all, I've come to understand that adding a supercharger will put more strain on my stock engine, and eventually cause it to fail sooner that it would otherwise, all things considered. I understand that 8-10psi is the "safe" zone and the tune is very important to prevent detonation and engine failure. I've heard extremes in both directions, where somebody will say that their engine blew the first time they started it up after installing a charger, and other times people will say they have 150k miles on their mustang, all while having the supercharger. I understand that a lot of how much wear and tear your engine gets is related to how you drive it and how often, and I'm not concerned with blowing my engine anytime soon since I drive like a grandma 95% of the time. However, there are a few things I'd like to ask.

What exactly gets fatigued in the engine over time due to supercharger use?

What is likely to fail due to aggressive driving with a supercharger (I've heard the connecting rods are guilty here)?

I understand that forging the engine is the way to prevent it from blowing when using a charger, what components need to be forged?


Also, I'd like to share this link with you all and get your opinions on it. I was browsing the Brenspeed website and came across this:

Brenspeed Stage 2 B302 Rotating Assembly

They say these are the components they use in their built motors. Are they forged components that would be safe to use with a charger? Is this a kit I could buy and put into my stock 4.6L engine or are they specific to another type of block?

Finally, what mods would need to be done to accommodate a supercharger? I've heard long tube headers are important.

Thanks for all the help guys, I love the community here at AFM and check the website like 10 times a day!
 

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Here is something I found on the thread about the blower... page 27 to be exact.

Sqidd does a fantastic job explaining this. Hope this helps.

Copied and pasted from the blower thread page 27
quote from Sqidd!!!!


I don’t think “boost” has been advertised or explained correctly by the industry. And then the common “base knowledge” that we have is lacking in scope or detail.

I’ll try to keep this short, I tent to ramble.

A blower is only an air pump. When you pick a pulley size you are picking how much air it will pump through out the RPM range. At the end of the day it takes “X” amount of air (plus a little fuel of course) to make “X” amount of HP. Of course engine size, compression ratio, engine efficiency, etc have a factor in this but on a basic level if you jam 1000cfm of air into a 4.6L V-8 motor it will make almost the same HP as if you were to jam 1000cfm into a 2.5L 4cyl. Granted the 4cyl with have more boost (see next paragraph).

Boost is only a representation of the restriction that the motor represents. For example, if you put heads/cams on a blown car and don’t change the pulley it will “loose boost” because it has less of a restriction. This doesn’t mean the blower is not operating efficiently or there is something wrong. It just means it’s easier for the air to get through the motor. In the above example it will make more HP and have less boost.

Boost is not the only factor when the term “safe” comes up (in regards to the combustion chamber). Boost is coupled directly to timing, air/fuel (A/F) and intake air temps (IAT’s) when it comes to keeping things safe. They all work together. For example, you can run a high boost numbers and not lean on the timing real hard (were going to assume good IAT’s and A/F) and have a perfectly safe combustion chamber. On the other end of the spectrum you can run low boost with a lot of timing and put holes in pistons. A/F has a lot to do with what is safe in the combustion chamber also. If you run leanish numbers (12.0-12.5:1) it doesn’t matter what your boost or timing is, you will start hurting parts. And lastly if you have high IAT’s they will hurt the combustion chamber almost in the exact same way running lean does. The good thing about our ECU’s is that they automatically start pulling timing as the IAT’s go up as a “safety net” in case the car is heat soaked or the IC pump stops working. So by itself boost does not hurt parts, only boost in combination with aggressive timing, high IAT’s or lean A/F ratios hurts stuff.

An example of “Shaky Science” and a contributor to some of the disinformation out there is Kenne Bell (I have one on my car…..junk). They will tell you that their kit will make “X” hp at lets say 8.5psi. If you read carefully though you will see that they always run all of their “tests” at 11.5:1 A/F ratio with……..wait for it……25deg of timing! That’s a LOT of timing and they are only getting away with that by using 100+ octane fuel. They say for consistence sake. So if you back the timing down to even “aggressive” (16-18deg) you are looking at a considerable HP loss. When I was at 450hp-ish the base KB kit was supposed to make 450+ at 8.5psi. I put the supplied pulley on my car and had it tuned it made 438rwhp at 10.2psi. Yeah, their “8.5psi” pulley made a touch over 10psi on a stock motor and it didn’t make as much power as it should have with less boost. We ended up running 16deg of timing to keep things nice and safe. And to poke another hole in KB’s “Science”/claims you could only get 1-2 runs before their crappy IC system heat soaked and it pulled enough timing to chop 50-60hp out of it. All of their published numbers are with a constant IAT that is not pulling timing. That is not at all representative of real life unless you are making a pass, cooling the car down for an hour, making another pass, etc. Just driving around town has the IAT’s up near the point where it will start chopping out timing.

Now for the other “safe”. The safe threshold for the stock motor is 450-500rwhp. Assuming everything that is going on in the combustion chamber is okey dokey the safe HP is based solely on the mechanical strength of the motor (Rods, pistons, crank, block, bolts, etc). In actuality it’s the rods that give up first. It doesn’t matter how you are making HP, be it with supercharger boost, turbo boost, nitrous, or naturally aspirated (as long as it is not being spun to the moon) the lower end will only take so much force before it breaks. It doesn’t care how that force is being made. Be it 5psi, 25psi, a bucket of nitrous, etc. the bottom end does not know where the power is “coming from”.

So at the end of the day to keep the motor safe you want to exert only 450-500rwhp on the mechanicals of the motor. And you want what is going on in the combustion chamber to be safe. For the first tune on the test car we went REAL SAFE with the tune. We could have easily thrown more timing at it and leaned it out slightly and made close to 500rwhp without changing the boost. So there is your sliding scale. Do you want 450rwhp with 12psi and super safe timing or 450wrhp with 10psi and timing with a little attitude? We went with the safe route. We could probably run 89 octane with this tune and not hurt a thing. We won’t be doing that, but we could.

One last point:
I’m taking this on the end because I didn’t see where to fit it in exactly above.

I think a lot of the reason that higher boost numbers are considered “scary” by the masses is because of what high boost numbers generally represent. And that is high IAT’s. The more you compress the air (boost) the hotter it gets. But that is not a constant. For example, a 3.0L blower making 18lb of boost is going to have MUCH lower IAT’s than a 2.0L blower making 18psi. The smaller blower has to spin the rotors faster to make the same boost on the same motor. Spinning the rotors faster creates more heat because it is less efficient. In the stock GT500 blower/4.6 3v combo we are actually spinning the blower SLOWER than the GT500 does stock. The GT500 blower is actually a more efficient blower on the 4.6L than it is on the 5.4L. So where the GT500 5.4L is making about 450rwhp stock at 10psi the 4.6L with the same blower is making 450rwhp at 12psi (more restriction, smaller motor) and the blower is being spun slightly slower on the 4.6L. The GT500 blower is actually a better “match” for the 4.6L than the 5.4L in regards to it is not “working as hard”. And less the less work the blower puts in the lower the IAT’s will be.
 

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and my $.02

the rods are the weakest point inside of the engine and will fail first. You need to run a good tune or you will have detonation inside your cylinder and its as bad as the word sounds for your engine.
 
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Also, I'd like to share this link with you all and get your opinions on it. I was browsing the Brenspeed website and came across this:

Brenspeed Stage 2 B302 Rotating Assembly

They say these are the components they use in their built motors. Are they forged components that would be safe to use with a charger? Is this a kit I could buy and put into my stock 4.6L engine or are they specific to another type of block?

Finally, what mods would need to be done to accommodate a supercharger? I've heard long tube headers are important.
Headers are nice in that they reduce boost and actually add some hp/tq. I went from 9.5 lbs to 8lbs when I added them, but gained about 25 rwhp. Important does not equal necessary though.

I've used Brenspeed several times for parts/advice. Give them a call. They've suggested things when advisable, and discouraged me from others that they considered a waste. That's uncommon in these economic times.
 

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Definitely feel free to give us a call at 574.549.9559 if you have any questions. We are certainly here to help and arent going to sell you something you dont need.

On a side note, this rotating assembly will hold a LOT of power and is certainly hard to beat for the price vs. quality of parts.
 

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Definitely feel free to give us a call at 574.549.9559 if you have any questions. We are certainly here to help and arent going to sell you something you dont need.

On a side note, this rotating assembly will hold a LOT of power and is certainly hard to beat for the price vs. quality of parts.

Hello Brenspeed,,


Not to thread jack ,, but it is related,, How many RPM's can you turn your stroker ?? I'm starting to look for one that'll stay together at 7000+ rpms with 12-14lbs of boost ...
 

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Hello Brenspeed,,


Not to thread jack ,, but it is related,, How many RPM's can you turn your stroker ?? I'm starting to look for one that'll stay together at 7000+ rpms with 12-14lbs of boost ...
That shouldnt be a problem at all. We ran this same engine for atleast 3-4 years in our race car shifting at 7k+ each shift.
 
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