turbinesurgeon

I'm wanting to put 10 psi on a 70 mm turbo into a mostly stock 5.3L (cast block). My co-worker owns a Silverado that has VVT, and I really like the way his truck feels off the line. Besides another way to control boost, I figure VVT will give my set up some nice off the line performance before the boost kicks in.

The Mast guys say that lower Valve spring pressures are needed to run VVT, but boost guys say you need stronger ones to insure valve seating.

My questions are...

1. Would stiffer intake valve springs really hurt a VVT set-up that much?

2. Is anyone even trying VVT and Boost, what are they doing?

3. Is there a "Turbo Rule" that makes running VVT with it a bad idea?

CarsandWomen

iTrader: (19)

there is not yet a valid way to control the VVT either with our PCM's or standalone controllers. Many have looked into this but we just havent seen anything good enough yet

slow67

iTrader: (2)

I'm pretty sure EFILive has access to those tables, as well as the aftermarket Mast Motorsports PCM.

On the other hand, you have to get a limiter kit to limit the travel when using aftermarket cams, so your valves don't hit the pistons.

Vetal

iTrader: (3)

Don't know specifics of that engine, but many Evos/Hondas/Nissans run 30psi of boost with VVT

CarsandWomen

iTrader: (19)

really? I hadnt heard that, any links to more info?

look for a few pm's from me in the near future, I picked up a 4l80e

turbinesurgeon

I've herd about this problem as well. I was thinking of fixing it with a set of custom JE pistons with deep valve reliefs. Would fix the interference problem and lower my compression ratio. That way the only head work I would have to do is the valves and springs.

Everything I read on boost says the intake valve springs need to be stiff to seat under boost, and that the exhaust valves need to be able to withstand heat. So I think if I just use the stiffer intake valve springs, and use the softer ones recommended for VVT just on exhaust side, I shouldn't be as hard on the phaser. Then all I need are higher temp valves.

The Mast HO L99 cam has 1 degree of overlap, is that about right for boost? I'm also reading cam overlap is bad for boost, but some is needed to spool the turbine.

Am I at least on the right track? I would like to try a VVT Turbo combo in my build.

slow67

iTrader: (2)

Heres a screenshot. You can download a demo copy of EFILive and go thru tunes (this is a 2010 Camaro A6 stock tune).

turbinesurgeon

I just returned from over seas and I'm still very interested in boosting a VVT equiped 5.3L. The basic set-up I'm thinking of running is an aluminum block, LS6 heads, Truck manifolds, LS4 cam, custom pistons with deep valve reliefs, and a Mast PCM to control it all. I think 10 psi should net me about 550hp & tq, and I'm building the rest of the car to be a streetable auto-cross car.

Am I on the right track? Any ideas to add to my basic set-up I am open too, looking to just build the engine once and tune as I go.

turbinesurgeon

My build has already started, my car is under the knife as I type. I have an LS1 in my garage that will be getting a rebuild, and I would still like to boost it with VVT.

I'm still looking for alittle info to help me be succesful. I've read quite a bit of info on both topics, but am still finding nothing on LS engines with both.

Anyone.....

turbinesurgeon

......Anyone? Guess not

Oh well, for the same kind of $$$ I would invest in a turbo, I can sink it into the block and have 434ci. Gonna stay n/a & vvt.