Basal Skull

IAT's were a lot higher in the upper gears too if I remember the previous posts on Phelix's run?

Felix

Here's one of those runs:

Kevin

Basal, it is the load request. And yes, the programming will seek more timing vs higher boost. But at the same time dump timing when knock and IAT climb.

My Stage 2 tuning kit while tuned on the Maha dyno's without IC cooling. This allowed us to tune for extreme worst case situations. I wanted to design and build a kit that would appeal to "most" drivers. Smooth power delivery on a stock engine platform were the main goals. Felix as I have told you before in multiple threads, fill your car up with 100 octane Ron + Mon/2 and do your top speed runs.

Basal Skull

Kevin, that makes sense. So in 3rd, you make max torque at lower rpm and boost (advanced timing). The reason max torque in higher gears is at higher rpm is because if you look at the graph, in higher gears, the rpm range starts >5000 rpm. The engine is doing it's best to maintain power by increasing boost at the higher rpm. If you did a roll on from lower rpm in 4th up through 4000-6000rpm, we might see different things (more similar to 3rd gear? - but probably different d/t duration of load).

So I understand a little better why you see high torque dyno graphs at lower boost ... quite different in real life situation. So you can get max torque with this kit at ~0.75 bar but need the higher boost at higher rpms to maintain it (but this also causes more heat).

Phelix maybe you just need taller gears to keep your rpms lower!

malcolmd

I've realized that you don't have to be a brain surgeon to understand this now!

To highlight the point about effect of load as a function of the rpm range that we expose the engine to by virtue of when we choose to change the gears in a speed run, I've appended two graphs. Firstly, a plot showing the speed/time plot for three runs: Red - stock with a 0 - 120+ mph WOT run, Blue - a stock 50 - 120+ mph run commencing in 3rd at about 3700rpm, and Black - a UMW Stage 2 run also commencing in 3rd at 3700rpm. The latter two expose the engine to significantly higher load as you might expect. Note that in all but the 3rd to 4th changes for blue and black, the rpm only drops back to about 5000 with each and every other change.



The point is best seen in contrasting the two stock runs. Below, you will see that G Max of 4.2 (the point of max instantaneous TQ) occurs at 5000rpm for the red run and coincides with the instant after the power is on after the gear change - a sure sign that real peak TQ is higher, but at lower rpm. As for the blue run, where load has been higher and the engine has seen a wider rpm range, G Max is 4.5 and occurs at 4700 rpm, yet as expected the G is also 4.2 at 5000 rpm. For the record, the UMW Stage 2 produced a higher G Max as expected at 5000rpm.



So we need to remember with these acceleration runs, when instantaneous PWR and TQ are calculated, the numbers reflect the load under the conditions that the engine is operating - most notably, the rpm range we grant by the gear change point.

LA964RS

Yes, I've never felt it much good going over 6-6200 rpm. I know some guys want to run all the way to redline, and I think the UMW program allows you up to 7k....but w/the drop off, don't know which is more efficient way to run the car. Interestingly enough, w/these motors I think on any given day you can feel where the sweet spot will be....and it moves around a bit.

Basal Skull

Nice data Malcolm! The only problem with people knowing your day job on a public forum is that you can't say something too silly or else it may hurt business...

LA964RS, don't know which is better way to run the car either, but it seems to make sense to drive it so that you are near max torque/acceleration to get the best numbers. Seem to remember someone talking about using a continuously variable transmission to keep rpms at max torque to get the best acceleration, at least in theory anyways... also may keep boost lower/lower IAT's at max torque.

Ryojo