Engine/Transmission (1994 - 1998) Effect of timing on spool up?

[DESL PWR]

Been reading about some of the popular singles out there and on more than one occasion have read about them being a little slow to 10 psi or so and then building boost very rapidly to 40+psi. Would it be safe to say that running advanced timing is a contributor to this? Would leaving the stock timing make spool-up quicker?



Don't want this to be a who's turbo spools quicker debate, just a set-up/tuning question.

 

[RustyJC]

Retarding timing, since it starts the combustion sequence later in terms of crankshaft rotation, delivers more energy to the exhaust when the exhaust valve opens but less to the piston crown. Therefore, speaking generally, retarding timing will help turbo spool but may penalize engine responsiveness, power output and brake specific fuel consumption. Optimum timing requires balancing these factors.



Rusty

 

[bmoeller]

I never noticed a difference in lag at all with the PDR 40 I had. Truck felt snappier all around. My new 64/14 is a bit laggier on the bottom, but not to awful bad. After it hits about 10psi, it flat takes off. Clears the smoke pretty good when she lights.

 

[DESL PWR]

Bmoeller, did you bump your timing up before or after you installed the PDR40? I see you didnt move it too much so it might not have that much of an effect on the bottom end while gainig more on the top. Like rusty said its a trade-off. Finding the balance is key.

 

[Jim Fulmer]

Not too bad but begins to fade a tad from 18-20 and a little more from 20-24 then falls off after that. Allot of that has to do with Cam Timing, there are people out there (non vendors) that have optimised Cam Timing and this is not much of a factor for them.



Jim

 

[WaynesWorld]

Not too bad but begins to fade a tad from 18-20 and a little more from 20-24 then falls off after that. Allot of that has to do with Cam Timing, there are people out there (non vendors) that have optimised Cam Timing and this is not much of a factor for them.



Jim

Jim,

Are you saying for daily driver 17 max ?



And for more performance 18-20, but just a little lag.



DSL PWR,



Yes, Bryan & I did his timing before he did the new & improveed turbo. :-laf



The lag comes from the bigger turbo not the timing. IMHO



WAYNES WORLD

 

[bmoeller]

Bmoeller, did you bump your timing up before or after you installed the PDR40? I see you didnt move it too much so it might not have that much of an effect on the bottom end while gainig more on the top. Like rusty said its a trade-off. Finding the balance is key.

Wayne and I did the timing last year after I had the PDR40 on the truck, but about 3 weeks before the DDP4s went in. Still have the stock headgasket, so we didn't get carried away with the timing. If I had o-rings or a new marine gasket and headstuds, I probably would've gone to 17-18*.



A 3k GSK and a PDR or F1 cam or on the list of things to do. Both should help the spool up. Don't know if I'll get either done this year, or not. May have the fuel injection pump checked out, and up the CCs. Who knows. Maybe even have it rebuilt to 913 pump specs.

 

[Jim Fulmer]

If your headgasket can handle it there is nothing wrong with 18-20, after 20 is allot for the street but I have run 20-24 for years.



Nothing really wrong with a stock cam, if I were to do a cam change it would be the last thing I would do.



Jim