Reduce turbo lag

[JLEONARD]

Doing some research for my son. He wants to reduce turbo lag.
Currently he has a 2005 single wheel with TST Power max CR tuner, Fat 62 turbo, bigger injector nozzles (not sure which ones) , ATE manifold.
Truck has 100K + miles and he tows quite a bit. Not real heavy, usually a 4 place enclosed snowmobile trailer, towing to Maine or upstate NY from Ct.
He thinks he needs twin turbos.
Any thoughts/suggestions?

 

[fox]

Smaller turbo

 

[JLEONARD]

Smaller turbo

Suggestion?

 

[AH64ID]

Which 62?

Tuning would be my first go-to, but more information is needed.

 

[cerberusiam]

Have him try the twin turbo options on the TST, that should help but it may over power something else.

A fat shaft 62 with a 74 turbine on a 14cm housing is going to spool a little slow, same compressor on 71-72 turbine in a 12cm housing will work a lot better on low and mid range. You loose some on the top end but if it is a DD and towing rig not much loss.

Other option is get a Smarty and stack it, then, have John build him a UDC tune to spool the turbo better.

 

[Tuesdak]

Lag is a misused term. You either mean the wait while the engine and rig build enough RPM to light off the large turbo or the true "Lag" of no throttle to the time it takes the smoke to clear after flooring it at high enough RPM the turbo will light at.

You simply CAN NOT spool a large turbo if the engine RPM is too low. The Torque Converter holds the engine RPM too low for the large turbo to light off.

Either rev the engine up to the large turbo's power band say with a high stall converter or use a TDV Turbine Diverter Valve.

I have done both with large turbo's on 6.5 GM diesels. The TDV sounds like #e!! is trying to escape from the exhaust and takes 2 PSI boost at 2000 RPM to 10 PSI Boost at 2000 RPM.

http://www.dieselperformance.com/index.php/product/index/202P

The High Stall converter will let the engine "flash" up to the Turbo's light off RPM from a dig. So hang the front wheels on the curb in reverse with a loaded trailer. Floor it in reverse and the 6.2 hits 2200 RPM. A moment for the turbo LAG and it lights off. Smoke from exhaust clears then both rear wheels light up on concrete and start to walk around with a fully loaded trailer. It's not safe to back a trailer in reverse unless I am in 4x4 on that Rat Rod. (The TDV would not allow enough RPM from a dig to do this.) I did not try a combo of both a TDV and high stall converter.

Choosing between the two I like the high stall converter better on the 6.5/6.2 because the under-powered engine is in the powerband all the time. (The 6.x needs to have the high RPM HP to back up the TQ.) Now on a 5.9 Cummins that has much more low end torque the TDV may be a better choice.