night ryder

iTrader: (20)

me and a buddy where talking tonight and he came up with a interesting question. lets say a stock ls1 can handle 550whp tops. lets say it takes 12psi to do that on stock head/cam on pump gas. now if you where to head or cam it you would not make any more power.

here is the theory im my mind. the cylinder can only handle X amount of air into it before parts start to fail. so if you where to add a head/cam you would have to lower the boost as you can only hold X amount of air correct? so really it is totally pointless to add a head/cam if the bottom end cant take it right? either way it would have the exact same stress on the bottom end right?


im sure its been brought up before, but i was lazy and felt like posting something for a change.

ShevrolayZ28

iTrader: (4)

That's where it should stay.

You want to get as much air in there as you can and then mix it with fuel, compress it, burn it, spit it out, etc. The right heads, headers, and cam will help make power regardless of FI or NA.

MadIceV8

iTrader: (12)

I think I get what you are getting at. On a stock bottom end motor you would be wasting you time to do H/C/FI. You can do FI + one of those, but both will put you in the danger zone. BUT if you add heads to lower your compression that will help the bottom end.

Now if you have a built bottom end and want all the power you can get... then go a head and do everything.

JosephIV

iTrader: (14)

When you add a heads/cam package you see an increase in power. Ask yourself why is that? You must have increased the amount of air that your engine is receiving, and combining that with more fuel and a proper tune resulted in more power.

I have seen cars make 10 lbs of boost supercharged through the stock heads and with the stock cam lay down some good RWHP numbers. After a good set of heads and a cam the boost decreased but the power increased. Why?

The heads and cam increased the amount of air that the engine could ingest and the lower impedence (read as lower boost) registered as a lower boost number while still making more power.

Your maxed out stock LS1 with a supercharger might make 550RWHP with 12 pounds of boost, but if you add heads and a cam you could possibly see those same numbers with a drop to 10 pounds of boost. Now imagine what happens when you spin the supercharger faster to make 12 pounds of boost again? Like magic, you make even more power!

night ryder

iTrader: (20)

your not understanding what i am saying, i understand that heads and cam will make more power by increasing the the air entering the cylinders. what i am trying to get at is you can only put so much air into the cylinders before parts start to fail.

what im trying to get at is the fact you can only have X amount of air in a cylinder at 550whp, weather it be forcing more air into it or having more time for air to enter (such as a cam and larger runners) you can only have so much before it will fail, but either way the amount of air in the cylinder will be equal no matter how you get it in there.

night ryder

iTrader: (20)

but when going FI the same rules do not apply as far as getting the air in there. if it takes X amount of air to get to that point on a head/cam car, on a FI car you could just turn up boost to match that amount of air and either way you would produce the same amount of stress on the motor while making the same amount of power. but when you already have X amount of air in there and cannot put anymore in, it would not make a bit of difference to add heads or cam. if you have the bottom end for it, then yeah getting a good head/cam combo with 20lbs of boost will make great power, but with a stock bottom end you air limited to how much air can go in before parts fail. exhaust is a whole different story. im just talking about the amount of air in the cylinders.

you get it. compression is a different story as that deals with timing. my example was with the same size combustion cambers (i should of mentioned that)

EPP

iTrader: (22)

If you added the heads and cam and dropped the boost to where the max rwhp was still in the 550 rwhp range (less typically on our Mustang Dyno) then the engine may live longer as there would be less chance of detonation due to cooler iat temp's. You would have to rev the engine higher for the boost to come in, and combined with the heads and cam possibly taking away some of the bottom end power, you could lose a lot of bottom end power. Bob

98Z28MASS

iTrader: (6)

I see what your saying, but you will have a more efficient setup with a good heads/cam package and will be able to make the same power with less boost. It wouldnt seem to matter but I would think that a 550 rwhp ls1 with a good FI heads/Cam package at say 8-9psi would last longer than a stock heads/cam Ls1 at 12 psi due to less stress on the engine components? I could be completely wrong but thats what id assume.

ShevrolayZ28

iTrader: (4)

It seems like you are still sort of saying that adding heads and cam won't make more power, but I think in all practical cases it will. The laws of physics always apply.

The discussion is beginning to go over our heads a bit but here's what I think. The root of the misunderstanding is in the underlying principles of FI and why FI makes more power. A key factor that you are overlooking is that gas(air) is very compressible. (Of course, air is not infinitely compressible, but we do not come close to reaching maximum level that air is compressible to when we are filling the cylinder on the intake stroke.) Therefor, the amount of air that can fill a fixed volume (your cylinder) is variable.

During the intake stroke and cylinder filling: With FI, before the compression stroke, the cylinder is filled with compressed air. With NA, the air is only drawn in. So there's more air filling the cylinder with FI.


With the right set of heads and cam, one can better manage events throughout the combustion process, and make even more power.

Of course, as the power output increases, regardless of FI or NA, there is more risk of breaking parts. It seems that HC is pretty safe on stock lower end LS1s, and FI, if well tuned, is fairly safe, too, but all three bring us to a power level where we break stuff with more frequency.

Am I making any sense? I have a feeling I am still misunderstanding your post lol.

night ryder

iTrader: (20)

that makes since, but im my scenario detonation is not a issue. i know that with less boost you can run higher timing, but the bang in the cylinders can only be so much before rings start to fail. so you can still accomplish the same hp with less boost but there would still be the exact amount of stress on the motor making 550whp correct? im thinking it does not matter how you get the air in there (head/cam) its the same amount of air.

but you are right about the AIT. the air would be cooler with less boost and there is less chance for detonation.


but there is the same amount of air in the cylinders no matter how it got there.


still a misunderstanding . i know that heads and cam will add power as the air will have more room, more time and better flow to get in the cylinder, but the cylinder can only hold so much before the the rings give out. like i stated on bobs post, about the only difference would be the AIT.

let me put numbers on it, and it will make since. lets say air could be messured in grams (i know it cant be, but just to put a number on it). to make 500whp it takes 58 grams. ok now with 12psi 58 grams will make its way into the cylinder with stock heads and cam to make 550whp. now if you where to put heads and cam in there, the air would get in there more efficiently, but could only hold 58 grams before it is to much. so at 8psi you can fit 58 grams in the cylinder, but it would be the exact same amount of stress on the motor no matter how the air got in there because both scenario's put 58 grams of air in the cylinder. the only difference would be the AIT. is that more understandable?

crf538

iTrader: (3)

im pretty sure i agree with you on this one, at least thats the route ive taken with my car, i figure theres no need to do a head or cam swap if your limited by rods or rod bolts to begin with.

with that said a friend of mine (1a-play) made 9.70-10.0 passes in a full weight c5 on a stock short block for a long time before it finially came apart, and he had some heads that flowed really well and a pretty big cam. Im pretty sure he was only running 9 pounds of boost, so would the increased boost that was needed to get that power output with stock heads have made the motor break more quickly? i wouldn't think so but maybe.

OUTLAWZ RACING

iTrader: (9)

You can push a ls1 past 550 hp, Here is how, Lets say boost is a mesure of restriction the better flowing equipment and the proper set up will net you gains over the entire powerband. Why? Simple the cylinders can hold so much air right but it boils down to how fast the air and how well the motor use it. Lets just say for example a guy buys a fast 92, Trick flows heads the best ones for a stock bore, a D1sc , 1 7/8 headers and a highlift cam around 600 lift and 230's in duration. This all goes on a ls1 stock, oh and the proper fuel set up also. Max boost is 12 psi, That car will see well over 550 hp to the ground and may not even need the full 12 psi. Due to the fact that NA alone that will push it past 450 hp. It also boil down to how the motor use the incoming air and expells it. The faster you feed it the volume wont be as critical. Bottom line is I really dont know what the hell im talking about but its common sense the more efficent you make the motor the higher hp it will have hell look at ford 4v motor alittle 281 with a huge blower and they surpass 550 hp easy. 4v per cylinder and how the motor use it comes into play.

night ryder

iTrader: (20)

read post #10. im not saying a ls1 is limited to 550hp, im just using that as a number to go off of. i am well aware that heads and cam make more power on the same boost level, but you are limited on a stock botom end. if you where to have a forged bottom end then hell yeah, push as much air in those cylinders as posible, but im talking stock wise.

night ryder

iTrader: (20)

that is the question i am asking. im sure it would cause more of a chance for detonation, but i think there would be the same amount of stress on the motor either way.

davidadavila

i fully understand the what he is saying, if i am correct what he is saying is that no matter how you get to 550 there is no point in adding more power because the parts in the cylinders are going to fail after that.........what everybody is trying to tell you is that its posible to take it beyond that level if you make the power more efficientlly...the answer that everybody is tring to convey is that a motor is a pump and by helping the intake side or the exhaust side of the motor you are creating more power with less stress on your motor, yes wyou will make the same power either way but helping the intake side and the exhaust side of things you actually reduce the stress in the cylinder... hot rod magazine had a stock 5.3 engine with a mp turbo making 550 horses they put in a ls6 cam and made 100 more horsepower..and ran the power tour day and night......now that proves you can take it beyond that point safely ......in the same sense if the motor had a blower cam and some heads it would of made more power with probably less boost and lasted longer.....