Steve Bryant

iTrader: (1)

I am interested in stroking my LQ4 to 408 CID (4.030 X 4.0) and doing some mild porting work on the heads (bowls and blending). This is a daily driver and a tow vehicle. I'm curious about the torque increase if anyone knows. I think that it would be around 15 to 20%. I plan to continue running 87 Octane.

Any thoughts on this? Is anyone else thinking along similar lines?

Thanks in advance.

silent1

iTrader: (3)

You should be able to get around 400 RWTQ. Look in the group purchase section for the A.P.E. 409 special. Very nice price for what you get.

1BADHD

If I had the $$$$, I would be doing it in a heartbeat!

Steve Bryant

iTrader: (1)

Thanks guys. I'll be curious to see what others think. I'm also thinking about doing a dyno run on my truck now to see what it is doing after the mods. Has anybody dynoed a stock 6.0 that I could use as a bisis of comparison?

whitt1

I think if you want to tow,get a Duramax,if you want to haul(a$$ that is)get the stroker.

jdpanero

Do some tuning to the DMAX, and you'll have both.

Gordy M

iTrader: (2)

It would be nice if you could get the DMax and Allison trans in a Yukon, but I do not think that is possible. Like Steve, I am interested in a stroker motor for towing. Hauling a 4000 lb trailer with a 3100 car and equipment can put a strain on a stock motor.

Neil 6.0

Steve, see my sig. That was 2 years ago, bone stock with 11K miles.
Are you planning on running the same cam?

Steve Bryant

iTrader: (1)

Neil,

Do you actually have a graph of your torque and HP? If not, I assume that the torque peak was around 4,000 RPM. It might be of interest to you the the guy at my local dyno shop here in Wichita said that flywheel torque is about 18% higher than at the wheel with a modern automatic transmission in good condition. 305 X 1.18 = 359.9 pounds feet of torque which is dead on for a nominal engine.

Yes, I do plan to run the same cam that I have. I have talked to Lunatti about building a 408 stroker and they said that this cam would work great. Also, from the research that I did, this cam is about perfect for daily driving and good mid range torque. More lift equals more power, but only in the upper RPM register, not what I want. The same is true for stage II and beyond porting and closer LSA's.

Yelo

The power loss through the 4L60E is about 23% and the 4L80E is about 27%......I would LOVE to only have an 18% loss