I like how you pick apart my statement then add other vairables to strengthen yours.

Her never said anything about a cam, or any other motor work. He simply said dropping compression with 6.0L heads which should actually put him closer to 8.6-8.7:1 depending on the gaskets used and running 16psi (on an otherwise stock motor with it's normal efficiency). In that instance how am I wrong saying that unless he has the tune spot on that he isn't going to break something? Everyone knows that the tune is key and with crappy gas like 91 octane you don't have much of a cushion.

Yes, it can be done, Parish did it, I've done it for awhile on my VERY similar set up to what this guy wants to run. But rather than lead him to believe it's all peaches and he'll suffer no pitfalls I'd rather err on the side of caution and tell it like it is... On a stock 5.3L with only dropped compression you could very easily break something with that much boost (if all things are done right and he is making the power he should be for that amount of boost) and low octane.. Period.

 

Then why don't you run 30#s on pump gas then?

 

i realize that by changing the valve timing with a special cam i can lower the dynamic compression ratio that way, but wouldnt i be pushing fuel out the exhaust that way? or maybe you mean the intake valve timing...

the 5.3L motor is already at 9.5:1 compression so im starting to like what youre saying...heh.

i think im beginning to understand what youre saying about how you can leave the intake valve open longer (i think), but wouldnt that kill throttle response, because at idle, when its not under boost, it should kill the volumetric efficiency of the engine as the piston is coming up, it will push some of the charge out of the intake valve back into the intake. now when its under boost or at higher rpms, where there will be boost anyways, i can see where it would help.

i guess i dont understand the dynamics of cams and timing that well...but id like to hear more of your suggestions.

 

so your motor will make the same power at 16#s as it would at 30#s? and would make the same power on 93 octane as 110? if so why not run 0 boost on 87 octane?

 

hes saying that if you had a motor that moved the same amount of air at 16#s as another, less efficient motor at 30#s then they would both make the same power even though one is running twice the boost.

the octane of a fuel basically means how fast it burns as it is a measure of the amount of unbranched alkanes to branched alkanes in the fuel. 87 burns quickest, 116 burns slowest, having the most complicated chemical structure (more branches). so i think hes saying that you could make the same power using low octane as high octane if you controlled the timing right. i.e. less advance for low octane and more advance for higher octane....i think.

what hes saying about the boost is this:
imagine blowing a gallon of air through a 2" diameter straw in 1 second, then
imagine blowing a gallon of air through a 1" diameter straw in 1 second.
the pressure in the small straw will be higher than the large straw, but they will both move the same amount of air.

i think the 0 lbs of boost thing was the wrong way to put it though because youll never have 0 lbs of boost if you expect to have more than 0 lbs of boost in the chamber. it will at least have to equal the pressure in the chamber, and if there are restrictions before the chamber (heads, intake, throttle body etc..) then your boost guage will read higher than the pressure in the cylinder.

 

"what hes saying about the boost is this:
imagine blowing a gallon of air through a 2" diameter straw in 1 second, then
imagine blowing a gallon of air through a 1" diameter straw in 1 second.
the pressure in the small straw will be higher than the large straw, but they will both move the same amount of air."
ok but im saying if you have the same turbo (not a little stock vs. a huge race turbo) at 16 pounds then up the boost to 30 the one with 30 is going to be alot more powerful.

 

What he is saying is perfectly correct in the ways that i understand boost. What I don't like is the way he comes across when saying it.

The problem is that you didn't mention changing anything else about the natural efficiency of your motor via cam swaps or head design so I gave my opinion on the info you gave since I was running a similar setup.

My new motor is all about getting the air in and out as efficiently as possible using much the same ways Bryan described and some of it is almost exactly how my engine builder described it which makes me even angrier that I can't agrue anything with Bryan... LOL

I don't even talk about PSI on my new setup because I honestly don't care what it is. We are going to build the motor for a turbo and just add boost.

 

well thats a given, but wasnt what he meant. say both engines are making the same power, one at 16# and one at 30#. the one making the power at 16# has a far less restrictive path from the turbo to the cylinder, and is better at getting the fuel and air into the chamber, which is what makes power.

 

i am curious though...why do stock turbo motors (grand nationals, turbo supras) come from the factory with low compression, like 8:1. why didnt they just adjust for this with tuning? do you know something that the car manufacturers dont know?

 

I can say the same about a 427 c5r with an f1 at 16psi making only 822

Get off your high horse, your talking to people like a pompus *** as usual

 

Well your info was very good, hell I learned something, just work on the delivery

 

Your very right Brian, people who come to me with wanting to make power, would also like to be able to drive their cars without hassle. I know I like my car that way also. I also care about gas milage and smog because my shop is in the good old california with crap *** 91 octane.

I can also say I follow alot of the same theory that you do as well. One of our cars I am proud of is a little 370 CID iron block I builts, heads/cam, D1SC blower seeing about 12-13 psi on the gauge right now, long tubes, high flow cats, fuel system, ect.... Puts down almost 700RWHP and just under 600TQ. It passed smog the following weekend as well on the same tune. 9.1 static CR inthe motor, about 22-20* of timing in certain areas. So at this point we are pushing the limits of the stock MAF, or we could be making more if we awere not. 91 octane, no booster added. So not too shabby.

Its all in the heads and the cam. I think I could get more out of the cam though, it was my first cam choice to start on thie setup, 224/232 116LSA, .558/.568. Heads are almost at 90% intake to exhaust ratio. I had them hog the crap out of the exhaust, I didnt care about intake.

And the guy daily drives it every single day for the past year so far.

I would say though at 800 plus, ditching the maf is a good choice with boost because it just becomes a pain to work around.

Rick

 

Bryan, you going to the track soon? You really going to just run 93 and no alky or race gas?

 

You now have an F1R and are going to push that for more power with 93 pump gas and no alky?

 

yeah, 2 bar is next for that car as well. I cant stand the MAF at this point. the 2 bar will also be going on all our future turbo cars including mine.

Rick

 

This isn't true. Look up the combustion energy of different octane gasolines, they are virtually the same. Octane is a measure of detonation resistance, and THATS ALL. It does not necissarly mean the gas burns slower, or burns cooler (although it can, like ethanol and methanol).

Or people who want to make a lot of power without a lot of effort. Or people who want to make the most power possible. Or people who want a lot power power, but don't want the drivability compromises that come with a hot cam/head package. Which is easier, installing a better flowing motor or turning a **** clockwise? And then you get to the point where you can't make your engine flow much better, but you still need more power. Might as well turn up the boost. Some people don't give a **** if their car only runs well on race gas, since they don't want its full performance that often (ie dyno-queen Supras).

Remember Marko's Supra that put down 1500whp? They disabled the WG and maxed out the 6-bar MAP sensor in the process. Not effecient at all, but hey it worked for 2 dyno pulls (the 2nd pull cracked the block).

Cars with tough motors that operate on their knock limit on pump gas can see large gains with just a few points more octane. Supras, Evos, etc. on 93 octane generally gain 2-4 mph just by mixing in a few gallons of good gas, and letting the ECU figure out the timing. Is running sub-optimal timing at 19 psi as effecient as running full timing at 16 psi? No. Does it make more power? Yes. Unfortunately 2JZ and 4G63 pistons are crap, and don't really work with the quench on the head. So your car with flattop pistons and tons of quenc might be different. I am also told its easier to get swirl with a 2-valve head, but I don't have any experience with head design.

Power is about cylinder pressure at the right time in the compression and power strokes. To get more cylinder pressure, you need more air/fuel flow. You can get this with a poor flowing head/cam with more boost or a better flowing head and less boost. I agree the better flowing head is going to have more det resistance at the same power level, since there will be less heat (boost) in the intake charge, and less residual exhaust left over in the chamber (as it will probably have a better intake/exhaust presure ratio). But I don't think the difference is going to be dramatic. I am speaking from experience with my and my friends' Supras. Mine went from stock turbos with a horrible pressure ratio to a T66 with a pressure ratio of ~1:1 at most RPMs and 19 psi.

Sorry to be rude, but I think your completely incorrect.

 

Sadly, the Pump Gas Drags is not to me LS1 friendly. Any guy with a 540ci BBC and a turbo setup will put us on the trailer. John Cunningham (I have met him) went low 9's on just HP with a 540ci with I think Big Chief heads.

Going for 900rwhp with an F1R, 93 pump gas, 22 degrees of timing, with a 10:1 block and 75 lb injectors sounds like it's going to break at some point.

 

sorry bryan i think youre completely incorrect...

 

that wasnt completely horrible, your getting better

 

While I certainly don't subscribe to everything Brian W says, and I think PUREVL owns a do-nothing dyno queen and is a punk that runs his mouth with no real track times to back up his 1000 rwhp mean machine, but YOU SIR ARE TOTALLY INCORRECT! The effect of high octane is that it slows the flame propogation and cools the combustion event. That is the reason that low compression cars slow with too high an octane in the tank, and high compression, boosted and/or juiced cars speed up... because they can apply more of the same with no fear of detonation. They do so because octane controls the burn much more effectively. That is the end of the factual discussion.

PS-
While I know that my statements regarding MY OPINION of PUREVL and Brian W may instigate, I want them to know that I respect them because they are two of the few that are trying to advance the LS1 sport. Please don't take it personally that I don't share most of your views, I still respect the effort. Thanks!

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