WheelmanWS6

Hey yo,

So I've been giving myself an ulcer thinking about next year's project. I know I'm gonna be shooting for some big power (650+ RWHP) but I'm not exactly on the "How" I wanna get there

I guess it boils down to two categories: Big cubes or small (maybe even stock) cubes with FI.

There are pro's and con's with each obviously. Personally, I have always wanted to do a Procharger setup on maybe a stock cube, built motor. But then I look at it, and I could probably get near the numbers for a bit less money stay with an N/A setup on maybe a 427 or 454.

How about power efficiency? I'm guessing I would be safer on a big cube setup since I would be making a lower HP/CI number. I know both big cubes and FI are both gonna build good torque throughout the curve, but which curve is gonna be better for a street/strip car?

Reliability? I supposed you can make a case for both with proper tuning, fuel system, etc. I'm guessing long term and FI would be a bit more maintenance.

Risk? More could go wrong with FI I would assume, given boost adjustment, detonation, octane issues, etc.

Just thinking a bit out loud here. I would appreciate the insight and experiences of people who have hammered out this issue themselves. I didn't make a poll because this is more of brainstorm session that a cut-and-dry decision right now.

Thanks guys

InchUp

iTrader: (2)

So if I understand this right, your question is, "At the 650+ rwhp mark, which motor will be more reliable making that 650+ rwhp; a small cube motor with forced induction or a big cube N/A motor?"

First of all my question to you would be which two motors are you considering? What is your definition of a small cube motor and a big cube motor?

The simple answer is; forced induction.

jason02Z

iTrader: (10)

650 is a lot easier and prob cost a lil less than big ci n/a.. stock crank 364-370 6.0 sand 76mm turbo pump gas.. reliable and make more tq and hp through its power curve.. especially if its gonna be a street car. big n/a will need the lightest and and biggest head and intake to make 650whp..very loud and radical unless thats what u like and not a daily driver with 10mpg compared to 20+ boosted. And a D1 will do it no prob too..u get that real aggressive blower sound a can get away with a more lumpy cam. https://ls1tech.com/forums/dynamometer-results-comparisons/940027-late-model-racecraft-lsx-454-a.html check out LMR big N/A motor bad ***

WheelmanWS6

Good point, I should have been more specific.

I guess the main options would be "Big Cube" of 427-454 range, big cam, aftermarket cast heads, etc.

vs.

"small cube + FI" would be a forged stock cube motor, low compression, blower cam, etc. on a D1-SC pushing 12-15 PSI.

stevied916

iTrader: (30)

370ci with pt70 or similar turbo would be the ticket

99blancoSS

iTrader: (115)

FI is always cheaper, but not always more reliable. Hoses bursting, belts slipping. It can be done reliable but its not cheaper and the qaulity of gas effects how good it runs. Honestly it seems the FI boys are always having to ding on something or control deotonation on hot days on long rides.

A N/a Big cube what ever you want to call it doesnt have those issues. It cost more to build but n/a is old school and true bragging rights. Anyone can make power with FI , look at all the shitboxes with home made ebay turbos.
Turbo's are more efficient to answer that question as well.

This is about budget and personal taste.


I like N/a so I went with the biggest ls I could stuff onto my Camaro and have it make 600+ reliably. Its not a cheap build at all, but to be perfectly honest we're hoping for 650 at the wheels. This is on pump gas 91 octane. 457 cid

WheelmanWS6

Some good points in there, but what really has the most power for the buck? Keep in mind, supporting mods as well.

I can't say which I prefer, since both are intruiging options. I suppose just want to makes the most reliable power I can.

99blancoSS

iTrader: (115)

fi power is cheaper to hit 600 rwhp but not always better

Diesel_29

First off, I would address the question of "What do you want to do with the car?" Is it going to be a street demon? Race car? DD? Or all three?

Secondly, don't get too caught up in dyno numbers. You want power that is useable. No need for 1500 RWHP if it run's 10's. (I've seen it happen several times. )

Also, I wouldn't say a FI set-up is cheaper than a N/A set-up making the same power. A well built, reliable FI motor can run you 8-9K+ just for the turbo, and another 8K+ easy for the motor set-up. Not that you should be worrying about money when making 600+ HP anyways...but a N/A motor in that power range is going to take more engineering and research than anything. So, in conclusion...I say go N/A. It might cost you the same, might not. Might cost you more, IDK, it's all in the set-up. But you'll have bragging rights over the FI people, not to mention...if somebody pulls up next to you and hears a turbo spooling, they might think twice. So, you'll have more of a sleeper type thing going on.

But...BIG CI+FI=

camarols1

iTrader: (17)

A 600rwp N/A car is not going to idle like stock, that's for sure.
If someone does not think twice about the sound of the idle, then they deserve to get smoked...
It is all about personal preference, build what YOU want because YOU are paying for it.
I personally ditched the old school SBC/Procharger setup because the local cops gave me a bunch of crap about the noise, even though it was not that loud at all.
The new turbo setup will be half as loud and twice as powerful.
A no brainer for MY needs. What the cops don't hear, won't hurt ME...

Good luck man!

InchUp

iTrader: (2)

One of the many benefits of running a turbo or two is that you can use the motor you already have, rather than going out and buying an LSx block and going to town on that. If you have an LS1, running premium gasoline at the pump gives you a range of about 12psi or less, maybe more with a great tune, safely. 12 psi on an LS1 gets you a minimum horsepower output of about 480, and a whopping max of about 710hp. The variance is all up to how well you build the system, the efficiency of the turbo and intercooler, the cam, how high you rev the motor and lastly how the LS1 reacts to boost...which it does well. At 12psi I'd expect no less than 550hp, probably 600 or so after tuning issues are worked out. That alone will create all sorts of traction problems for you.

You wont need anything but .010" over hypereutectic pistons to clean up the block and prep it for boost and considering the stock LS1 sits at 10:1 compression I'd look to ported and polished up 317 heads from a 6.0L, mill them down to 9:1 or so compression. Finding a junkyard set of 317's is fairly common and cheap compared to the well known 243's that seem to go for no less than $300. Put $300 into a set of 317's for head work and milling and they'll outflow stock 243's all across the entire rev range, except make gobs more low end torque and improved throttle response thanks to the smaller intake and exhaust runners. Another bennefit to the 317's is that they have enormous 71cc+ chambers so you have a lot of material to work with to mill them down to 9:1, once you figure out the cc's of your hypereutectic pistons. I'd only tap the forged market if you plan to rev really high above 6000 all the time.

Other than a small camshaft swap for a 1200-6200 rev range (mid 220's duration and .550" lift on a 114-116 LSA) and a good tune I'd be very happy with the motor. It'll have a very flat torque curve after the boost hits, rather than a peaky torque curve a bigger N/A motor will see. If you DID want a little more displacement, I know 4" cranks are fairly common for the LS1 and that'll sit you at a 382 I believe. I know you'll be up and over the 600hp mark then, with additional torque down low to help spin the tires off the line.

Just suggestions...that's all.

Reject

iTrader: (24)

you can do a ls7 engine and alittle bolt ons and get you close to your set number for a na block..... oooor be smart and get a turbo setup built right... wanna cruise at 400 hp thats fine wanna race that car thats punking you out at the light... hit the up button on the EBC that 400 just turned into a 500 right there, want more? hit the button up higher hehehe power increase right then and there, no pullies to swap no new heads to port.... you control the power level in your cabin

lets see a na car do that as quick as a turbo car

now... what looks like a smarter choice?

WheelmanWS6

More intresting stuff, thanks guys.

Originally, I was planning a D1-SC at 12-15 PSI (depending on CR, octane, etc.) I was gonna do an entirely forged 347, blower cam, aftermarket-cast heads, etc.


However,


If the LS1 reacts as well to boost as you all say, I could probably get away with .010 over with some forged pistons (maybe rods too) on a stock crank/stock block. Maybe mill my Patriot Stage II LS6 heads, expand the combustion chamber and go bigger valves with a blower cam, fuel system, etc?

Would this kind of work get me into my horsepower range AND maintain driveability? I don't mind spending the money where I need to, but if this the best bang for the buck, why go overboard for minimal gains? Like Diesel_29 said, why makes excessive horsepower if you're not setup for it?

More thoughts? Thanks for keeping this going guys, I like where this is headed.

styoung

iTrader: (4)

you dont want to mill the heads, that will make the cumbstion chamber smaller, raising the compression and you dont want that with a fi motor. you want lower compression.

InchUp

iTrader: (2)

Yes and no. No, one does not want to simply lower the engine's compression. Instead one should be after the right compression ratio matched with the turbo, camshaft, exhaust, boost pressure, octane availability, intercooler efficiency and tune. A turbo engine must never be reduced to a low-compression slug just to have the boost turned up. One should shoot for the highest compression ratio allowed without pre-detonation or pinging, at the desired boost level.

Since the stock crank is easily good for up to, and past 600rwhp, I'd leave the crank alone unless you plan to spin past 6500 rpms all day long, every day with hopes of 1000hp. The rods are the weak link in these motors and it would be wise to just replace those, along with the pistons. Select the pistons based on your compression ratio needs after you know which heads and head gasket you're going to use. I would not be so hurried to run to the forged rotating assembly store every time a turbo engine needs building. T6 hypereutectic alloy pistons have similar strength properties to forged pistons, but T6 pistons have the advantage in ring land area where great strength is most important. The T6 pistons also have a high percentage of silicon, making them great for minimizing thermal expansion and heat transfer. Though forged pistons will do the trick, T6 pistons at least merit some investigation before purchasing a set.

As far as the actual method of forced induction, credentials will show how many supercharged users covert to turbo. Assuming you use an intercooler the way a proper setup should be built, factoring in a 2psi loss for all the tubing and intercooler blockage sits you right around needing a turbo that can produce 12-14psi of boost up to 6200 rpms on an LS1. That will equate to about 10-12psi of already chilled boost at the throttle body intake. Doing the simple math, assuming a volumetric efficiency of 85%, you'll need a turbo that can operate a 1.82 pressure ratio at 964.4cfm or a 1.95 pressure ratio at 1033.5cfm. If you can imagine then, you're doubling the capacity for the motor to inhale air, and depending on how well you manage thermal expansion you will see a good percentage of that doubling in horsepower as well. 12psi of boost, properly cooled and with the necessary bolt-ons, 600rwhp is easily obtainable. With a built bottom end (forged rods, T6 or forged pistons), supporting valvetrain and good heads, I'd think 700 flywheel horsepower is a good goal to set that will live an easy 50k miles without troubles, where the valve springs will probably have to be changed first.

Now to find the right turbo. That I leave to you because only you know how you want the motor to run.

silverbandit0996

iTrader: (2)

More cubes plus the jug. but thats just my opinion.

WheelmanWS6

Good information, Thanks InchUp.

I guess I'm just having trouble finding a starting point. Do I pick a targeted CR? a max boost range? match a heads/cam? So i know my goal is 650 RWHP. Is there anyway to calculate the octane-to-boost-to-compression-ratio? How do I know when I'm running all those things appropriately without pushing the limits in terms of detonation?

As you said, I don't want a limp motor just to have to crank up the boost. I'm very detail oriented to matching my setups.



That was a thought as well, since a good CR + nitrous coincide well together. Since a big cube motor would be built well and balanced, it would be an easy add on.


However, I think, I really wanna do a supercharged motor at some point. I think next season will be the time, so I'm gonna start getting ready now.

randomnine7

iTrader: (23)

454+gt45r+150 DP !!!!

InchUp

iTrader: (2)

That is a very good question actually...where to start. As you pointed out you have many options of heads, pistons, camshafts and target compression ratios but you're leaving out three important topics of discussion: Compressor efficiency (how much heat will be put into the boosted charge), intercooler efficiency (how much heat will be taken out of the boosted charge) and finally (but not only) availability of high grade gasoline around you.

So...first question, since it's as easy as driving to the gas station to find the answer, what's the middle grade or highest grade octane level of gas around your area? Depending on what you're willing to pay for will determine what ideal compression ratio to run, but after a butt load of calculations.

I'll leave the calculations to later after you've found these 2 points of interest that I (we) will need to calculate things.

1. Figure out which turbo best suits your build, at least by using the two points I gave you above with the pressure ratios and the CFM flow rates and graphing them on various turbo's compressor maps. Call up Garret and have them recommend a turbo if need be. Figure out the efficiency of the turbo at, say, 13-14.5psi of boost.

2. Measure your car and put your thinking cap on and think about where to put the turbocharger (which side mostly), and figure out where you'd like the intercooler to go along with all it's piping. Find an intercooler that fits, and one that is mass produced so that if you need a replacement down the line you don't have to wait weeks or months for a custom one-off to be made for you. Then ask for it's efficiency, which should be in a percentage, same with the turbo's efficiency rating...it too should be a percentage rating.

After those figures are sorted out, the real fun begins...

WheelmanWS6

lol InchUp you are the man dude, lemme know if you're ever in Chicago cuz I owe you a beer or two or ten.


I also notice you keep replacing my word "supercharger" with "turbo" But I see what you're saying. The efficiency of the boost is absolutely as important as octane when affecting hazardous situations like detonation.

Personally, I'm more interested in a D1-SC or possibly an F1-SC setup. The only turbo setup that has really turned me on so far is the APS setup, but even that I don't think is for me. The plug-and-play capability and good torque benefits of a supercharger are appealing to me.


Around here, best gas for daily driving (which is still my aim for this car) would be 93 octane. Now, whether I trust this as actual "93" octane, dead on spot, 110% of the time, is questionable.... To play it safe, lets call it 91-92 octane.... I had some issues with my gas before when I had my LT1 and all the tuning and diagnostic software for it. If i make a track visit, I would likely fill up a tank of 100 octane race gas.


Back to your valuable points: Compressor and intercooler efficiency.... do these things have any impact on CR? So, would lower compression ratio be proportional/more forgiving to less compressor/intercooler efficiency? Or is this where octane comes more into play?


I feel 12-15 PSI on a built shortblock with a moderate blower cam, a stage III, high CC, 243 head with good-sized valves would be my most realistic build.... And its under those elements that I need to pin down a CR, which should hopefully tie everything together, no?


Thanks again InchUp, you've been a big help.