Boosted LS 408 or 364 in my chevelle?
 

Boosted LS 364 or 408
Hello,
Not not sure if I am posting this correctly. If not then point me in the direction.
I have 1970 chevelle that I decided a few years ago during my restoation to pitch the 454 and go LS twin turbo. From there the fun began. I have read so many forums that I am more confused than ever. It all come down to $$ at the end of the day. I have a plan but the cost has risen during this build and I want to make sure the $$ are used in the best way. My plan was to buy a LSX375-B15 but I am not able to get enough info on it or comfortable with the warranty. If you have any input that would be great. I have a motor and trans in the car that I have been using for a mockup. It's a 1999 5.7 LS motor. I have a turbo mockup mounted using the 2010 camaro manifolds, BeCool radiator, Treadstone 1400HP IC, Truck belt assembly and the Holley LS2 dominator ECM and wiring with control for the 4L80E and the boost control.
My question is Can I buy an LY6 remove the VVT and put ARP head studs on it with a holley EFi intake and a cam to make the power I need for the goal below or would I be better to buy a 408 long block? Ref: Kyle Thompson motor sports motor.

Goals:
HP.....
92 octane fuel
I want the car to be quick and run 10:40s in the qtr on street tires.
Mostly street and little strip.
Full body car 3800lbs
3:31 12 bolt
4L80E mild build
3000 stall convertor
twin precision turbos 6766 (haven't bought)
44MM Tial wastegates
Fuel tank/system (confused)

yes go with the ly6 ,, i made 520 to wheels on low boost with a turbo too small for it actually .. .. i would get rods and pistons for the ly6 , keep the stock crank in it .. then never look back .. sounds like you have it all well planned out .,, those turbos are huge .. plan on making big power with them . i would go a lil smaller me personally , twin 60"s 62mm turbine .. fuel tank m i would just use the stock one , add a sump, and do a big external pump.. new holley 1800 i belaive they are.. twin pump setup,, $430 pump. .. 8an fittings and hoses ... with a return style fpr .. there are some cheap short blocks forged on ebay from some reputable shops,, asking like $2500-3500 for fully forged shortblock,, if i had the money i would going that route ..Just go forged and never look back . ..you surprass your et goal easily ... but your current et goal is attainable with stock ly6 ,,

pics of the setup?

10.40s is easily attainable on virtually any stock LS long block with either single or twins, even at 3800 lbs.

Here are some pics of my project

Those turbos are very efficient at moving a lot of airflow for their size.

A 408 or 364 will both do what you want them to do IMO.

I prefer the smallest motor I can build that still achieves good transient response and builds boost quickly. Normally a smaller motor will be more efficient throughout the operating range than a larger engine, but the turbos used will have the ultimate say in that. Which is why I say "normally". Every scenario can be different.

If it were mine, I'd build the 364 with a smaller cam and a cylinder head with a 215-225cc intake port and 2.04-2.08 intake valve. This will help the smaller engine build boost quickly and keep compressor efficiency high throughout the operating range.

I'd build a 408.

364 with twin 62s should get you well into the 9s at 3800lbs. The 62s would spool quicker also.

https://cimg4.ibsrv.net/gimg/ls1tech...f01b8b9da4.jpg
Well I went with a 402 ci ls with 317 ported heads, with twin 6766 .81 ar precision turbos with v band housing. I have the 4l80e and using a pro torque 3400 stall converter. I have 3:31 gears with a 26.6 my drag radial tire. Should I change my gear to a 3:73. I want it to be a very quick street car with some track time.

https://cimg5.ibsrv.net/gimg/ls1tech...320a434c0a.jpg

Keep the taller rear gear.

You will blow the tires off every time with a 3.73. Keep the taller gear and let the turbos work down low

....and the 6.0 vs. 408 discussion continues....

My vote 408 without questions.