Turbo lag... How much are we talking about?

[bgibbsunc]

Originally Posted by FReSh

I think some people in this thread may be confusing lag with boost threshold... The boost threshold refers to the minimum RPM at which the car produces full boost. Lag refers to the amount of time it takes to build boost after you hit the throttle while the engine is already at an RPM at which full boost can be made(above the boost threshold).

YEa this is why this gets confusing. When I talk lag I am on the same page as you. The time to build boost while already above the boost threshold. I know ppl tend to get confused with this subject thats why I stated from a stop and while cruising.

[jamesm]

the log i posted illustrates behavior above the boost threshold pretty well, i think. frankly i think anything below that isn't really worth lookin at or arguing about. how often are you at 2-3krpm in high gear wanting to go fast? you spend a lot of time there... cruising in vacuum.

[cantholdanymore]

Originally Posted by gdrider77

Comparison.

Not really fair comparison IMO. At one point that turbo is making 160lb-ft MORE than the vortec.

[King Tut]

Originally Posted by jamesm

the log i posted illustrates behavior above the boost threshold pretty well, i think. frankly i think anything below that isn't really worth lookin at or arguing about. how often are you at 2-3krpm in high gear wanting to go fast? you spend a lot of time there... cruising in vacuum.

I like the way you presented it. I might try to duplicate that with the slightly different GT2871R my car has. I think it would be good for someone who AutoXs with a turbo kit to post his opinion on transient response and performance. @GTB ZR-1

[jamesm]

Originally Posted by King Tut

I like the way you presented it. I might try to duplicate that with the slightly different GT2871R my car has. I think it would be good for someone who AutoXs with a turbo kit to post his opinion on transient response and performance. @GTB ZR-1

I'd appreciate that, for comparison's sake.

[s2d4]

Originally Posted by bgibbsunc

YEa this is why this gets confusing. When I talk lag I am on the same page as you. The time to build boost while already above the boost threshold. I know ppl tend to get confused with this subject thats why I stated from a stop and while cruising.

Neither of those two occasions will you be above the boost threshold.

[bgibbsunc]

Originally Posted by s2d4

Neither of those two occasions will you be above the boost threshold.

By cruising I meant a steady speed not actually cruising. Thats my mistake. I tend to troll around at about 3500 rpm which is right below my boost threshold.

[xwd]

Originally Posted by King Tut

I like the way you presented it. I might try to duplicate that with the slightly different GT2871R my car has. I think it would be good for someone who AutoXs with a turbo kit to post his opinion on transient response and performance. @GTB ZR-1

I'd also really like to see a GT2871 as I think it's the perfect size turbo for this car and something like autocross. The P&L uses a Precision 5558B but those come in all kinds of sizes and I'm not sure exactly which one they are using. I think it's going to be a little laggier than a GT2867/71 but produce more power on the top end.

Comparing the AVO plot to the Vortech is absolutely okay. I've looked at both the S/C and turbo systems and while I really like the Innovate for its simplicity and torque it's hard to beat a turbo, and the lag on the smaller turbos on this car is pretty much nonexistent above 3000 RPM.

[gdrider77]

Originally Posted by cantholdanymore

Not really fair comparison IMO. At one point that turbo is making 160lb-ft MORE than the vortec.

I actually think it is pretty relevant. What i was trying to compare, was the different characteristics of the two. Peak HP is very similar, but the way it builds, the torque involved, etc..is much easier to see in a dyno plot compare.

In the end the vortech does make a bit more HP, but its so far up in the rpms, "to me" its worthless. I felt the dyno plot helps to show the difference, and would better illustrate how they compare in a driving situation.

I would rather have a bit less hp, but more tq down low. more fun and more usable in day to day. On the track or autocross, i do think the vortech may be more controllable and predictable, hard to say as i havent had either on a track yet....AutoX, I do think smooth power delivery aka..Vortech is probably a better solution.

Hope my post was informative, and was not mean to bash/promote one or the other, just to compare.

[nataku]

Originally Posted by FReSh

I think some people in this thread may be confusing lag with boost threshold... The boost threshold refers to the minimum RPM at which the car produces full boost. Lag refers to the amount of time it takes to build boost after you hit the throttle while the engine is already at an RPM at which full boost can be made(above the boost threshold).

Thank you for this clarification. I will stop misinforming, as I am now properly informed.

To answer the actual question now: when I am actually at my boost threshold I would say I have approximately half a second before the car pulls like a maniac. I consider this to be completely acceptible, but I could understand if that's the kind of thing you are trying to avoid.