shiny_lux

Hey fellas, am in the market for a new turbo, and taking a thread format that Ive seen stickied on other boards which has been a great help for sizing turbos to different aims/setups - thought Id start something similar...

So what rpm do you see first spool, and then full boost? Any other relevant info on setup etc. post that up as well (what turbo, boost pressure, displacement/compression, cam, manual/auto etc.)

Yes I know there are many variables but aim is to get a fair guestimate of anticipated spool characteristics for a given turbo and setup

Cheers!

VTC_WS6

iTrader: (9)

Stock bottom 4.8, TSP heads and a Tick cam, Turbonetics 78/76BB, 3800-4k on a T56.

Beanslsxnova

iTrader: (1)

My old set up was a
Gen 3 4.8
228/230 112 cam
Ls9 gaskets and arp studs
2 1/4 hot side
3" open down pipe
38mm wastegates
3" charge pipes eBay intercooler
3500 stall th400
3:25 gears 28" tall tires
3600lb nova

With a 69mm gt45 full spool at 4-4200 rpm
Everything the same but with a turbonetics 78/68 I would see full boost 3800-4000rpm

shiny_lux

Thanks guys, when do you see some positive pressure ie first spool?

Some more context, have bought a LY2 to build up for an engine swap. I bought the little V8 on purpose as wanna put together a setup that has a turbo sized such that I can roll around underneath boost for good gas mileage, but with crazy mid range not far away if I step on the gas (ie best of both worlds). So suppose looking for a turbo that starts building boost about 2-2.5k-ish rpm...

Keen on recommendations if anyone has any, though started this thread calling on all 4.8 setups as thought it might end up being useful to others with other spool targets...

Thanks
Matt

irrational

76mm on3 turbo stock 4.8 bottom end with stock 317 heads and 4l80e tranny stock converter with 3.73 gears.

I see full spool around 3600-3800 and beginning of spool around 3300ish engine is like a dead fish under 3k however it sure does climb the rpms quick enough.

shiny_lux

OK dead fish is not what Im after haha! Useful though is that with the factory truck cam?

Keep em coming folks, any setups out there built for lower rpm/mid range?

yenkomike

iTrader: (2)

I'm building one now with a stock 4.8 with ls6 valve springs and a on3 76 mm should be running in a couple weeks.

I have done a stock 6.0 with on3 78/75 and it was a stock engine with springs only and it spooled very fast.

rotary1307cc

iTrader: (5)

You realize rpm for full spool iis tied directly to the converter right? The converter will stall higher and higher as more tq is made, so you cant make a ton of boost at low rpm. RPM automatically rises even if the car hasn't moved

2000WS6TA

iTrader: (5)

thompson 370
PT88
Huron Speed non a/c kit
44mm wastegate
Tick stg II LS3 cam
Stock LS3 Heads
9.0 CR
T56
Stock 10 bolt. Stock 3.42s
Boost at around 3200 full boost by 4K maybe.

kingtal0n

iTrader: (1)

I can't live with too much lag. My favorite setup for stock 5.XL engines is twin T04E 50 trim compressors with 48 area/radius exhaust housings. It has a max of around 600rwhp~ to 650 if you have a manual trans and small rear, and spools so fast the engine almost feels N/A. Each turbo supports about 380rwhp if installed by itself on a 2L engine for reference (they flow about 44lb/min each iirc) I tuned a 2.6L with the same twin setup and it also made 650rwhp fwiw around 22psi of boost. (but thats just 2.6Liters!)

shiny_lux

Thanks for that, have been wondering about the twins route. Engine is going in a jap pickup that currently has an N/A LT1 and with that configuration at least there's a lot of height in the engine bay so a twin high mount setup could work. Something like a pair of TD05/6s should also spool pretty well on a 4.8 and shoe-horn in there OK. The reason I want early spool is the truck is a lump at ~2000kg, and big cam big runner big plenum current setup pisses me off as powerband is all top end

irrational

Well i am running around 8.5 CR with the 317 heads going for maximum power output on the top end. Just swapped in an ls1 cam in place of the stock 4.8 cam and it significantly helped out the spool times, also welded up a couple of leaks in the exhaust and adjusted my timing a little to help spool.

Now the low end is better, begins spool around 2800 rpm and full spool around 3200. One big thing that is holding back my low end is this massive stock torque converter at stock stall. Power braking stalls at 3k and spools the turbo over about 5 seconds to full spool. a 3500+ stall converter would really make this setup come alive.