SSpeeDEMONSS

I'm looking to start picking up some parts for this winters engine build. I was originally just going to go with a stock bottom engine LQ4 with some 317s and a turbo cam. goal was start around 600hp and work up to north of 800. Now I'm thinking that I will go with a stock iron block with all new rotating assembly to the tune of 408ci and some aftermarket aluminum heads. probably be in the mid to high 9:1cr. I figure the engine alone should be around 600hp so with a little boost should be easy 800, then by the end of the season if all goes well looking to turn it up and go for closer to 1000. Ultimately 1200 would probably be the absolute max and even at that I don't see myself going there for a long while. With that, what turbo or turbos would you recommend? From an idle on the hit the engine should flash to 4-5000 easily and looking to spin a max of 65-6800. Thanks for the help.

Garrett

Fbodyjunkie06

iTrader: (10)

I have had customers utilize the BW S366's on 408" engines with great success. At your power level you won't be pushing them very hard which will help keep IAT's low and tuning window wider.

They are not very expensive, as Forced Inductions sells them for 750 a pop with a cast compressor wheel.

Have had good luck with the 73mm turbine wheels and .88 and .91 housings.

SSpeeDEMONSS

Thanks. When I was still planning on a sbe 6.0 I was thinking about ebay GT45s so I guess the BW 66s are along the same lines, just much better.

Garrett

Blazeracer

iTrader: (2)

Got one running twins in a Cheyenne. I just built and iron block 5.7 liter running GT-35's on E85 with a blow thru QFT 750. I wouldn't run a stroker in a boat. Too much RPM and the piston's gonna rock at the bottom of the stroke.

Saw a vid from Nelson Racing Engines where the guy said in boosted applications, the gains don't outweigh the risk. It may just be me, but I listen to them guys at Nelson.

Blazeracer

iTrader: (2)

Check out this vid.... turning a stainless detailed B/C 7,200. I plan on using a 50-75 shot of nitrous for the hit once the turbos are dialed in. I had shitty home depot clamps on my cold side and it kept blowing the cold side off. The good boosted run is about 3 seconds of the first pass. Second pass is zero boost, one of the cold side pipes was completely off and didn't know it other than it was turning N/A rpms.

SSpeeDEMONSS

I want the added displacement to help get on the chargers as quick as possible. Any racing that may happen goes from idle and is over in 600'. Not going to take much lag to let the nitrous big blocks get out front and stay there. The top guys in our little group just ran yesterday at the lake and did 118mph in that 600'. A 468" and a 496" BBC with pretty good size shots.

Garrett

rpm-inc

iTrader: (2)

What kind of cam does a turbo ls jet boat get? Looking at swapping a boat with a 4.8 and 2 70mm on3 .68's that I have laying around. Also, what bellhousing and starter? The boat I am looking at originally had a 403 olds. Would I need a different impeller?

SSpeeDEMONSS

I was thinking of going with a stage 3 or 4 LJMS cam unless someone recommended something else.

The bellhousing for a jetboat is specific for a boat. it just covers the flexplate and if designed can hold the starter at the top, which is nice for access.

Whether or not you will need a different impeller depends on a few things. What cut is it now? What HP and rpm will you be spinning the new engine? Also, what pump?

Garrett

rpm-inc

iTrader: (2)

Its a berkeley 12je. B impeller i think. Would that work with the stock 4.8 cam spinning to 5200ish?? I would think with 15-18 psi it would make 525ish? I am going to pm you some other questions since I already threadjacked enough if that is ok?

SSpeeDEMONSS

You're going to want to spin it faster for a B cut. 525hp should be able to spin 55-5800 depening on where you are making the power. also, 5200 is really low for a 4.8 with twin 70s, even considering they are the little on3 units. I don't mind the hijack, it's turbo LS jet boat related.

Garrett

rpm-inc

iTrader: (2)

I just pulled 5200 out of the air. A little googling and it looks like 4.8 stock cam and will make power at 5800. What kind of speed would I be looking at? Its an 18' taylor ss.

SSpeeDEMONSS

I hope you don't plan on using the stock 4.8 cam with the turbos. But either way, 5800rpm with a B cut should put you low 70s for sure.

The AB/B cut in my tahiti behind my olds that only spins it 5k is in the mid 60s, just for reference.

Garrett

Martin Smallwood

iTrader: (2)

That would depend on the combo of parts aside from it being a 4.8 with twin 70mm on3 turbos.

Twin 70's on a 4.8 is a good bit of turbo, even though they are the china jobbies.

What intake manifold are you using?

If you go with a camshaft in your 4.8, you'll want to set the impeller up to allow the engine to see at least 6000-6500rpm to utilize the power the engine can make.

I would be glad to spec you a cam, as I have done many turbo LS jet boats before.

Speeddemon, I wasn't a sponsor at the time so I didn't mention it, but I can also sell you those turbochargers as well for 750 a piece.

rpm-inc

iTrader: (2)

I was thinking about the stock cam only because I have nothing invested in the 4.8, and the boat was a pretty good deal as well. Have the turbos laying around collecting dust, have a fuel pump, have some chinese head studs.......

So if were to cam it, what impeller would I need then? Yes, I understand the 70mm turbos are overkill, but I have them....They were originally going on an lq4 in a car before that project got changed up.

I was planning on just using the truck intake, although I have an ls1 intake as well.

If you could spec me a cam and springs that would be great.
Stock 05 4.8

Martin Smallwood

iTrader: (2)

I can't be certain which exact impeller you need, but you need to be in that power band IMO to come close to utilizing those turbochargers.

The truck intake would work just fine. I feel it gets discarded too quickly, as that manifold actually works really well.

For that set-up, this is what I would do for the camshaft:

218/218 .603/.595 114+4

I grind my cams on Cam Motion 8620 billet steel cores which are hand polished and cam doctored for accuracy. I would use a BTR spring kit with this camshaft and you'll also need hardened chromoly push rods as well. I can supply all of these parts, and if you need things like trunion upgrades, oil pump, timing chain, gaskets to swap the cam, head studs or lifters I can also get those parts as well.

rpm-inc

iTrader: (2)

OK, so 6500 rpm....What kind of speed is that????? Sounds dangerous LOL....

Martin Smallwood

iTrader: (2)

You could always back it off to 6000rpm if you felt the MPH was getting too dangerous for the impeller being used.

Or the cam could be made smaller and the RPM kept down even more, but the turbochargers will leave a lot on the table by doing so.

SSpeeDEMONSS

6000 to 6500rpm can be a really big swing in power. You can make 3-400 in that range with a D or go all the way up to 800-1000hp with a AA. Build your engine, dyno it if possible, then take the dyno graph to your pump guy and he will be able to get you set up. Build it for 6500, if that proves to be too fast for you then just limit it to 6000.

Martin- I'll probably be in contact with you about parts and setup this winter,

Garrett

Martin Smallwood

iTrader: (2)

Garrett,

Agreed, there could be a 100-150hp difference from 6000-6500. The cam I spec'd for him should peak around 6000rpm which should negate some of that variance, but not all variables can be accounted for. I like your approach the best, and it makes the most sense. Anytime you can have more data to build your combination the better.

Just give me a call or shoot me an email Garrett when you're ready. I can spec out a cam for you that will match those turbo's well. Number and email are in my signature.

Thanks!

SSpeeDEMONSS

Thanks. Once I get into a new house and my current boat sells I will get serious with the engine build. Unless I find a good hull for the right price.

Garrett