In an attempt to strive for perkier pickup, I advanced my low end 50-80, < 1000rpm by quite a fair bit.

There's no knocks, and indeed it felt good. My only concern is, am I advancing way too much to cause any harm ?

Comments ?

 

are you even hitting that cell?

 

Errm ..... when it's idling and when I'm just moving off ?

 

I was gonna ask the same thing as tephra, have you logged and verified you hit those cells?

I know every car is different, but from what I remember the only time a car hits those is possibly when your going uphill...? correct me if im wrong tho

~1000 RPM is super close to idle, i'd think load/rpm would increase a lot faster and hit entirely different cells than those from a standstill --> first gear.

 

if you want a lil "peppier" take off, in 1st, from a stop, set up your MIVEC map from 10 - 40 load and 500 - 1000 rpm like this. see how that feels...
load 10 20 30 40
500 3 3 3.6 4.2
750 3 3 14.4 14.4
1000 3 3 16.2 17.4

 

It might not show any knock either because it is way below the threshold, but this is the sort of areas of the map where knock is common to occur.

 

I've no MIVEC. But yeah, you're right ... they're literally skipped over during acceleration, touching them with a few hits before going into higher rpm.

 

That, however, is a good approach. Try it in your spoolup cells till you get a bit of consistant knock and back off a bit. What also helps is making sure that most of your spool area is ~12.5:1 and only gets rich by peak torque.

 

Timing in the spool area seems to make a huge difference in how fast the turbo comes on.

Correct me if I am wrong here but.....

I lowered the timing and added fuel to my spool area and the car seems to come on boost much quicker...like 300RPM or so quicker.

Since more fuel, to a point, makes more torque, wouldn't you want more fuel rather than more timing to make more torque and a punchier (if that is a word) car?

 

I've found that I can get the turbo to spool faster using the same methods. The problem with doing that is I was trading torque for faster spool. My car was faster overall with more timing and slightly slower spool.

 

Hmmm... I find the opposite.

The science is this though: more heat in exhaust = faster spool

You can do that by retarding spark (less fire in cylinder and more in exhaust) if you have cams. Trickiest way and will only work with special cam timing.

You can do that by adding fuel that can't burn in the cylnder and burns in the exhaust instead.

You can do that by leaning out (leaner burns hotter).


I make it leaner and add timing because you lose torque when you lean out. This works best for me because I drive the car on the roadcourse where it's never as simple as a 3k-8k pull. A lot of transition and spooling going on so heavy rich points are very abrupt when trying to manage power. I rather the smooth feeling of the leaner spool. I also don't like to run more fire through the exahust than I already do. I've melted too many parts at this point.

 

I realize that leaner is hotter, but in the case of out of the corner torque it seems that to have a bit more fuel and less timing to increase low end grunt would prove worth while.

The fuel and timing ramp rates would have to be smooth to have the same affect you are stating.

To keep the heat in the exhaust, I wraped the mani, and down pipe, and coated the hot side and the O2. So I understand what you are saying about having heat to spool the turbo becasue hotter air moves faster.

 

More fuel and less timing decrease low end torque, so you'd want to do the opposite to increase it.

 

I don't think he meant "less timing" I think he just means adding fuel and not increasing timing. I can see that working.. It just doesn't for me. I'm full throttle before apex and use throttle to steer many times through the turn so for me lean AFR is the way to go.


FYI if you're driving the car hard frequently I'm not sure about your way of doing things, I had an expensive mistake doing it that way. You basically blow burning fuel into the exhaust and that extra heat may help spool but it also autoignites all fuel/air that comes into the turbo shortly after. I totally melted a turbo (Inconel and all) including gasket and flanges this way. This is why I run lean with timing to help the torque. All that extra fuel is dangerous the way I see it. Maybe it is more effective though. I had heat wrap and coating just like you... but I realized that steel can only handle so much energy.

 

What actually happened for me is that I have been fighting the VIII tip in knock issue. I have big cams that hate timing and an FP Green that likes to spool and an HKS intake that hates to idle. So the issues compounded themselves.

I wanted to get rid of the tip in knock (yes I upgraded ROMs) so I started playing with timing and fuel. Much to my surprise the cams that hate timing responded very well to reducing timing in the 100 to 200 load cells. In doing so I noticed that I was a bit lean on spool...I want that nice 12.XX that we all shoot for. So, I gave it a bit more fuel.

By lowering the timing and giving the car a bit more fuel....not much mind you. The car is extremely responsive now. I love the point and shoot ability of it now. I like to Autox so this is the type of car I was hoping to build.