Ws6-dickie

hey guys so last year I bought a clean 58k mile 01 z28 roller to replace my 185k 00 z28 with a hci ls1 m6 , Ive got an entire budget of about 10-12k for everything . the ls1 in my 00 z made 412whp 419 tq through the t56 but I need a little more , so im stuck between rebuilding the current ls1 with a 383 stoker kit a new cam setup all bearings and seals. reusing my ported 243s and ls6 manifold ,or buying an atk408 shortblock and using my heads and intake etc . what im really looking for is something 100% streetable ac ps heat etc no crazy cam surge . Is it worth going 408 vs 383 or stay 346 id like to be close too 500 wheel but streetable the ls1 definitely needs a refresh regardless. how much more torque is the 408 going to produce compared to the others using the same heads and cam setup under 600 lift due to my pac 1218s , also need to rebuld my t56 plan on going with the tick level 2 and a mcloed rst clutch any input is appreciated thanks

Ws6-dickie

Ws6-dickie

anyone ???

Darth_V8r

iTrader: (4)

A 500 hp 346 will make about 430 lbs torque. A 500 hp 408 will make about 490 lbs torque.

The 408 will drive much easier

Ws6-dickie

gotcha I want as easy of a driving car possible my current car has so stupid cam surge between 1500-1800 rpm and its fairly small

Darth_V8r

iTrader: (4)

I would look at something like the 408, cam in the range of 232/240-114+2, great heads. Mamo 235 or TFS 245 type thing. Do not skimp on the heads. That is how a lot of 408s end up underperforming. Also do not skimp on the intake. Fast 102 likely your best bet.

That will get you there

Ws6-dickie

I can't really afford a new set of heads my current 243s are ported ,and I may be able to swing a manifold in the mic fast 102 or msd ?

Ws6-dickie

Specs on my heads

Ls7colorado

iTrader: (3)

If it were me I would sell the ls1 witch should get you around 1500-2000
Then keep your eye out in the classifieds and ebay untill a l76 from a G8 pops up ive seen them (and bought them) around 2500-3000 COMPLETE
That will get you a aluminum 6.0 block and the same heads and intake as a Ls3 (witch flow better than your current ported setup)
Then just have the bottom end rebuilt with your choice of a 408 rotating assembly and cam, if your going to be running pump 93 even the injectors that will come with the engine will support 500rwhp+
In fact 500rwhp has been done even with nothing more than cam and bolt ons many times.
You will easily get your 500 RWHP goal with less cam and the 4" stroke
If funds dont quite allow for now just run it as is and do the stroker kit later

With that being said there is NO WAY I would mess with the ls1

Darth_V8r

iTrader: (4)

If your heads are ported, and especially if the valve job is good, the displacement should get you there. If you compromise on the heads you may have to make it up on the cam a little bit (slightly bigger to compensate). Definitely don't want to suffocate the thing on the intake side though.

99 Black Bird T/A

iTrader: (4)

My dumbass is faced with exactly the same question! Send my old H&C 346 to Thompson Motorsports for refreshing and rebuilding as a 383 or finish the 408 I started buying parts for and planning two years ago. My quarter million mile 02 Z28 would be happy with either engine. So here's my .02 of opinion...


I think $12,000 to $14,000 is probably more realistic.

The stock fuel system is very good new and factory fresh. Less so in a 17 to 21 year old fbody car. New fuel pump like a Racetronix 255 kit and a set of ~42 to 48 pound injectors will likely be needed in this quest to 500+ whp

Depending on your exhaust you may want to upgrade to at least 1 7/8 headers if you don't have a set.

Likewise the cold air set up, lid (104 FTP) bigger 85mm to 100mm MAF, no MAF and SD tune, bigger TB and intake manifold upgrade, under drive pulley need to be considered.

Drive line/Rear end upgrades to consider?
New gears? Dana 60, Hawk's 8.8, MWC fabbed 9 inch, 12-bolt etc? Chrome - moly drive shaft? Carbon fiber DS?


The stock LS6 will strangle a good 383/408 or rev happy 346 LS1

Budget for a Fast 90/92 (used say $700) and sell the LS6 for $350-400 or send off the LS6 to TPIS/LPE for a 90mm snout upgrade for $350

While the 408 has much more potential and is the better choice for 98% of the driving and clowning a 383 will do just fine. The extra $500 to 1000 for the 408 (iron block 6.0 or aluminum 6.0) is really pretty minor vs cost of all the other parts for a stroker build.

The gripes with a LS1 383 are/will probably make 15 to 30 less hp, have low status with friends & Internet, get spanked by bigger bore LS engines and only cost $800 less than that aluminum 402/408 you really want

The plus for the 383 it's stupid simple and easy to pull your H&C LS1 and send it to Thompson Motorsports for refreshing & rebuilding YOUR LS1 as a turn-key 383 LS1 long block with your 243's refreshed too for a very reasonable price. There's a lot to be said for getting the car done, back together and running well on budget.

My 91 RS w/383 LS1 acts like a near stock LS1 with a mild H&C package getting 20 mpg normal and 24-26 mpg highway with 4.10 gears - the car is easy to live with day to day.

The 99 TA's 416 loves to visit the gas station Clowning 10mpg if that. Typically 14-17 mpg and rarely 21 mpg highway.

Unless your hardcore and race frequently, effectively the 383 = 408 for the "fun normal use in a daily driver type car" except for the ego "stroke", status and occasionally clowning.

Consider a refresh of the stock cube LS1 and go Procharger Small cam and drive very nice ? Can hit 525-550's pretty easy.

The RST can slip if it gets hot. Get the RXT instead. It costs a little more but is way better. I was going to do a RST with my Magnum and RPM Transmission strongly recommended going with the RXT with my 500+ whp engine build. I'm glad I listened to RPM Transmission.

Don't fool with a new short block or engine if you can't upgrade to better springs and go with more than .600 lift. Springs are cheap and going ~.625ish lift is free hp

Each extra cubic inch is worth ~ 1.25 foot pounds of rear wheel torque in a nice friendly streetable LS engine that drives close to stock with no cam surge and good manners when correctly tuned in my experience. You might get 1.35 foot pounds of torque or a little more in fully optimized set ups.

My old H&C LS1 346 - 404 rwtq drove almost stock
Current 383 LS1 makes 442 wtq and drives stock
My 416 is a very mild combo 471 wtq drives very well

Ws6-dickie

I have all the supporting stuff 255 pump 36lb injectors dts s60 4.10 gears arh 1 7/8 longtubes slip lm2 ls7 clutch

Ws6-dickie

Just some notes i

Ws6-dickie

This was the old forsale add from 2 owners ago on my black car no more engine or trans

99 Black Bird T/A

iTrader: (4)

Sounds like a sweet 01 Z28 in the build process
It's outstanding the car has an excellent rear end already. That helps a lot

Couple more comments...nice list...there's a lot of little stuff that will add up...like
New lifter trays $50
New lifters LS7 $100 or Morel / Johnson 's for $500+ depending on what you want
New timing set $65
New head bolts
Oil & filter
New plugs

I'd skip the eBay trunnion kit unless it's from BTR, Smith Brothers, WS6 Store, Summit, CHE or other well known reputable company. I picked up a nice set of stock rockers with the trunnion done by WS6 Store for just a little more than the eBay kit.

So which way are you leaning 383 or 408 etc?

Ws6-dickie

Honestly I have no idea I'm thinking 408 for more torque

Utinator

What is the ATK 408 LS you have listed? Is that a new short block?

Ws6-dickie

Yea new short block