Small Turbo on stock L29 454?

[Supercharged111]

And the GenVI can still run the 049 heads.

 

[SNOMAN]

I'm really just going to build this engine for street and occasional towing. In my mind I figured it would be cheaper and easier to turbocharge the engine instead of bore and stroking it. It does need a rebuild however.

I really I just need to spend the time and budget to see what will work best for me.

 

[RDF1]

Figuring out the right turbo will be the most difficult part.
I vote small compressor to support the power you need and a large turbine to free up the back pressure.
I towed for years with a BW S475/83 which has a 75mm Compressor and 83mm Turbine on a LQ4.
It worked great on 6-8psi.
Towing heavy stuff it would only take a second to build boost with stock 4L80E torque converter if i wanted it to. But most the time id never make it get into boost unless merging with traffic or just to hear the turbo whistle.

I have plans for a turbo on my 2500HD tow truck once i finish the 408ci engine. Thinking about a Billet 72 mm with a 87mm Turbine. Something to lower the back pressure in the exhaust but the compressor wouldnt need alot of rpm to push the air flow to make boost.

Id size it for the rpm/boost your going to spend most the time at. For me, its going to be 2300 rpms and 8-10psi.
Time will tell if i picked the right turbo.

 

[yevgenievich]

My machinist talked me into ditching the genV and going with a MarkIV block (stronger) and 049 heads for better airflow in the higher RPMs, although my cam designer has shown in his software that the peanut port heads make great power and torque down low.

I'm going with a stroker 496 for simplicity, around 440hp and just under 600ft lbs of torque. Final cam design isn't done yet but we're close.

If you guys want cam advice, I know a guy.........

I need a gen 6 cam with ls firing order...(basically 8.1l cam).

 

[SNOMAN]

So I've decided I am going to rebuild the engine and stroke it to 489/496. I think I will go with the long tube JBA headers, high flow cats, and Carven Type TR straight through mufflers.

With that being said I'm looking at these camshafts.
XR276HR and XR270HR.
XR276 224/230 @ .050 276/282 duration .51 lift 113 LSA
XR270 218/224 @ .050 270/276 duration. 51 lift
113 LSA

I feel I could get away with the 276 but the 270 might be better for me. Occasionally tow my snowmobiles and a 22ft Sea Ray boat. 3.73 gears. I also have a 0411 PCM. Just need to pin it and tune. Thoughts?

 

[Christian Steffen]

So I've decided I am going to rebuild the engine and stroke it to 489/496. I think I will go with the long tube JBA headers, high flow cats, and Carven Type TR straight through mufflers.

With that being said I'm looking at these camshafts.
XR276HR and XR270HR.
XR276 224/230 @ .050 276/282 duration .51 lift 113 LSA
XR270 218/224 @ .050 270/276 duration. 51 lift
113 LSA

I feel I could get away with the 276 but the 270 might be better for me. Occasionally tow my snowmobiles and a 22ft Sea Ray boat. 3.73 gears. I also have a 0411 PCM. Just need to pin it and tune. Thoughts?

I have the 270 in my truck, it's plenty of cam imo, for stock heads at least. If you're towing a ton, you might even consider a little bit smaller.

 

[WV_Dave]

In my state, I can't swap from a gas engine to a diesel engine and still pass the yearly inspection. I can get around this by putting antique license on, which doesn't require the inspection, but then I'm only legally allowed to drive it on weekends/holidays and to "special events."

That's what keeps me from considering a duramax/cummins swap.

 

[rearmountvortec]

Turbo BB vs dmax just depends on what you want for efficiency. Dmax will get great mileage, but they're expensive and a lot of work to swap. Turbo BB will get OK mileage if you can stay out of the throttle lol The dmax will make more torque at lower rpm, and sustain it much longer, but if you're not towing a lot the BB will do fine.

My rear mount turbo is just a gt45, but it is definitely small for the application. I think the heat loss from the turbo being 10' from the engine helps out with back pressure though, and I'm also only running 5 psi. As is back pressure is around 2:1, which is obviously higher than ideal, but could be worse. The turbo I'm running was mostly to get the system up and going, I'll upgrade it to a s475 or s480 eventually, but I need more injector and a walbro 450 first.

Currently I have a walbro 255 and 36 lb injectors ( flow ~42 at 58 psi), the injectors are maxed out at 5 psi the 255 is keeping pressure up so far but I am probably close to the max.

If you aren't planning to go much above 500 hp a walbro 255 should be enough, and a set of 36 or 42 lb injectors should work.

Stock injectors won't support much, so don't plan to use those, and I wouldn't trust the factory fuel pump personally.

Sounds like you system is pretty close to what Im shooting for! How much different is it than when it wa na? How much cooler is a turbo sound?

 

[Christian Steffen]

Sounds like you system is pretty close to what Im shooting for! How much different is it than when it wa na? How much cooler is a turbo sound?

The turbo sound is awesome in my opinion. I'll have to see if it can get a video, but it's worth it.