Quote (FMX_89 @ Oct 8 2013 05:33pm)

I should have explained that point a little further.


When the turbo(s) is undersized for the engine power will fall off early.  If you want it to pull to your desired shift points based on your gearing you HAVE to size the turbo correctly.  The only thing you can do then is turn the boost down to keep it at the power level you want.  If you do that then you really could have went with a lesser setup altogether unless you plan on making more power later.

You can have your 1100whp on a 440ci motor with 6 bolt heads that flow 350CFM but it will likely be at 5500rpm.  After that it will flatline and your backpressure will double or triple by your rev limit.  That causes ridiculous amounts of heat because the turbo is trying to overspin it's efficient range in the compressor map.  It's a trickle down effect.

With a procharger setup unless you fab up a wastegate on the intake charge pipe you cannot control boost on the fly.  It is based on pulley size just like your Cobra was.  At max impeller RPM it will only flow so much air.  The curve will look better than an undersized turbo setup.  The only problem you will run in to is blower life at max RPM and the heat caused by that RPM.


Suffice to say if you are going to undersize a setup both will give you high IAT's and low efficiency but the turbo engine will actually fall on it's face.  The supercharged engine won't.


My suggestion would be 72's if you are really considering twins and a 440ci setup.  Honestly though, that many cubes isn't necessary until you start getting into outlaw drag radial type of power.  It actually makes it harder to choose the proper turbos for the job.  You are better off with slightly less cubes (and backpressure) with a higher pressure ratio (boost) from an efficiency standpoint.  The outlaw guys are running 422-45xci engines and twin 80-91's.  By using the same size engine and much smaller turbos you are effectively limiting your available RPM.  You will have a low RPM stump puller type curve and your gearing would have to reflect that. If it is a highway car that is not what you want.  If you are trying to build it to run the number at the track too you will want to see what gear and RPM you need to cross the stripe in the right gear at a given mph.  1100whp in that vette should be in the 160's.

Quote (TeaRs- @ Oct 8 2013 06:02pm)

would my lq4 with 3:23 gears and the bw s9000 be enough to not hit the rev limiter? while keeping decent IAT?

Quote (FMX_89 @ Oct 8 2013 06:12pm)

I'm not familiar with that turbo.  Link me to it somewhere. 3.23's are a good place to start with an auto.  Which trans are you going to be running?  I need the 3rd gear ratio to figure it out.  I also need to know what kind of tires you plan on running.  Generally speaking the higher power a turbo car makes the lower (numeric) gear you are going to need.


This is actual racer math.  I enjoy doing this sort of shit.  It's not bench racing, it's physics.  Read my edit above on engine combos.  You can get into really long discussions with people that have doing this shit since my parents were born about what the optimum rod/stroke ratio is for a turbo car.  Most small block guys are running well under 400ci until they get to 2000hp.  There are many, many reasons why.  Building an efficient and reliable turbo setup is a lot more difficult than it seems at first.  You HAVE to start with a power goal, then pick your turbine, then compressor size needed to achieve than power, then you build the engine and select heads that land right in the sweet spot of the turbo's compressor map.

Unfortunately most people go about it in the exact opposite manner when building a street car.  They build a bottom end, buy some heads, and try to pick a turbo to match what they already have.  Obviously in the low power stuff (3 digit power) you are using what you already have most of the time with stock bottom ends.

Quote (justin_618 @ Oct 8 2013 06:38pm)

I'm actually rather glad k posted this now. I might not go 444lsx and just keep the little ls2 and run either 66s or 72s. I may just forge the internals and build the trans  bwcuase if the 444 is not needed then Fuck spending all that extra money on it lol. I don't have plans on going super gnarly for a really like time.

Quote (TeaRs- @ Oct 8 2013 06:18pm)

sorry its the s400 sx idk what i was thinking lol.

the goal still hasnt changed. 650-700 hp to the wheels. i figured the 3:23's  i figure would be plenty. and not make driving on the highway much easier on the engine.

http://www.full-race.com/store/borgwarner-airwerks/turbos/borgwarner-s400sx3-turbo.html

Quote (FMX_89 @ Oct 8 2013 06:59pm)

My best suggestion is to look around on LS1tech (not corvetteforum, they buy the most expensive thing on the list no matter what) and see what works.  Really spend some time reading in the Forced induction section.  It's where all of the smart, fast, and successful people hang out.  It is about the only section left that hasn't died.  There is still good tech in there.  Reason being Forced induction is the only area that is still growing and we are learning new things and getting new products.




Trans and tire?

The S400 is a size range of BW turbos.  They have everything from a 65mm compressor to an 82. Power ranges from 700 max to 1200.  I see a lot of guys using the S476 in T4 with the ETT wheels from ForcedInductions.  If you went with an S480 (S400sx-80) you could run it now and keep it for later on when you want to forge your LQ4 if you stay stock stroke.  It would make between 900 and 1000.  It's a real nice turbo for the money.

Call Jose at Forced Inductions.  He is a little hard to get ahold of but he knows his shit. They are the ones that are designing and machining all of these custom wheels.  They sell Garret, Precision, Turbonetics, BW, and their own custom setups.  Since he sells them all he is much less likely to have brand bias and sell you the wrong turbo.  I will buy my Garret T6 GT91 from him eventually.

Quote (FMX_89 @ Oct 7 2013 11:52pm)

7 stations within 25 miles and 25 stations within 50 miles of 62220.


There are 6 around O'Fallon which is where I bought my Formula.

You have to be honest with yourself about how much you will really drive a 1000hp car.  At first I thought 3-4 days a week.  Truly its more like 3-5 days a month for most people.  And thats if they dont break.

Quote (Culaza @ Oct 8 2013 09:29pm)

http://www.altfuelprices.com/index.php?bounds=38.19046+-90.28654+38.81046+-89.66654&fuel%5Ftype=2

I live a little over an hour away from 62220 ;o

Don't see many people from da midwest