There are several good threads discussing this. The first was from SilverSurfer back in 2004.

The one few people seem to know about is this: https://www.evolutionm.net/forums/sh...d.php?t=239025

...of course not many people live as high as us.

d

 

Cam timing is going to be highly dependent on the setup.

Using blanket -4/-1 isn't going to work for everything. I did considerable testing on this while settting up speed density.

Everything was backed up with not only HP but also the changes in AFR. All power figures are relative to 0/0 cam timing. I did 4 pulls (2 each direction) for each setting on the same stretch of road, allowing coolant temps to restabilize between pulls. As thorough as I could be considering it was street pulls. All done over about 45 mintues of total time. Also, it was a lOW boost. I wanted to observe the effects of cam timing on the torque curve without the turbo flow limit having a large impact. No ignition changes.

I'm running the FP 280+ cams, heavily modded stock intake manifold and IX turbo. 4500' elevation.

Moving the exhaust cam either direction from 0 lost ~5% above 5500 RPM. Even just a single degree. Advancing it 1 degree boosted mid range torque about 5% and spooled 200 sooner but as mentioned it fell on it's face above 5500 RPM. Retarding it 1 degree dropped mid range 5%, increased lag and still lost 5% above 5500. Moving the exhaust cam also made the car VERY knock prone. The car felt lazy with anything but 0 exhaust cam timing.

Moving the intake cam 2 degrees retarded picked up 2-3% up top (above 6500 RPM) but lost about the same below 5000RPM. Hit full boost about 100 RPM later if I recall correctly. Moving the intake 4 degrees retarded picked up 4-5% up top (above 6500 RPM) but lost about the same below 5000 RPM. Hit full boost about 300 RPM later. Both settings felt noticeably more laggy. -4 made the car knock prone as well. Anything past 4 degrees started giving up huge mid range with no gains in top end.

0/0 provided the best overall power curve and response, thus is where they are currently set. -4/0 provided the best top end above 6500 RPM and is what I’ll use at the track.

At higher boost where the turbo has a more pronounced effect, I would imaing it becomes a balance between the turbo and cams. I'll retest at higher boost when I've got a few other things straightened out.

 

Don't you mean the opposite for the exhaust cam? Advancing the exhaust cam is reducing overlap (just like retarding the intake cam), which should hurt spool, not help it. I'm just wondering if these were your findings or if you got it backwards for the exhaust cam.

 

Throw a 2.3 in it lol

 

...and it gets worse with different ramp rates and lob centerlines. I couldn't find any specs on my Helix cams other than duration and lift. There has been (and continues to be) a great deal of trial and error that mostly just benefits me.

d

 

C'mon....2.4 sheesh.

Seriously though, using standard 0,0 cam timing what other methods are people doing to improve spool and help low end torque ? ?

 

aluminum driveshaft

 

Did you already port your hot side and exhaust manifold? And do you have an aftermarket O2 housing? If so, you can hand port the flange where there is a sharp overhang and open the transition opening between the two sides. My spool is insanely fast, but I also have a 9 turbo.

 

Yep those are upgraded and ported to the hilt.

What are people's opinions on tuning for spool and low end torque???

 

What about the strategy of a big boost spike as early as possible and then a drastic taper right after peak trq. As much timing as possible, rich AFRs and shut everything down after 5k as heat builds up.

For an around town street car this would trade your HP for torque assuming you have decent boost control. No?

 

One thing that can go overlooked is the turbo itself. Play in the bearings can cause flutter and wobble, dragging out the spool. Slightly gunked up center section will cause drag on the bearing and slow the spool too. So can thicker oil cause slower spool. Cutting edge turbos are being designed with air bearings to radically reduce friction now

Probably not your issue but you can check by spinning the blades to see if they spin very freely or if there is some resistance to turning.

It is a known fact that using 0-20W oil reduces friction and allows that last few hp to be found. Many SCCA racers do this. I wouldnt do it on the EVO as the bearing load is high enough under spool up I would imagine, but might be worth some torque.

With some risk

Milburn

 

I agree that a high level of torque makes for a much more enjoyable driver. The fatter the area under the curve the better in my opinion. After all it is the area under the curve we operate in most. Who really cares about peak numbers?

 

Not sure if this is related to the thread. I just got back from the gym and did a 2nd gear pull, i heard a pop and couldn't see for a split second. Turns out the torque caused my fold up sun shade to pop open lol ...I almost died, again.

 

OHH OHHH OHHHH....please share how you did this AMAZING feat. You inspire me oh so much.

 

ECU Controlled Boost