My cam desgin
 

Been while since i have posted here but yes the all wheel drive car is still being worked on. The folks at HTP and myself have been hard at work planning out the last few phases of the build to make it ready for 2015 season.

Anyway, i have been working on a cam desgin and have been struggling a bit with duration. So i have drawn up a spread sheet to compare some other pupular turbo car cam designs. I will attach it for those who care to read it.

So what i am thinking i is this. My cam is is the top OEM for comparison is bottom. From what i know you have about .500 clearance in the chamber.

Cam Lift Adv Dur Dur @.050 Lift in MM LIFT Δ vs OEM DUR Δ vs OEM
Intake Jarod 0.432 225 10.96 16.13% 8.17%
Exhaust Jarod 0.373 212 9.47 16.20% 10.99%

Intake Stock 0.372 208 9.44 0.00% 0
Exhaust Stock 0.321 191 8.15 0.00% 0

Let me know your thoughts!

Cheers!

http://www.cosworth.com/media/335568..._2009_v1.0.pdf
Page 11......more data for your comparison.

Lift selection will be dependent on how your head flows at high lift, no point going for high lift if the head has already maxed out at a lower lift.

Duration should be a function of how high you want to rev. Personally I wouldn't get to knotted up in turbo cams versus NA cams, not sure it makes that much difference.

Lift it doesnt make a whole heap of difference. Lift is a function of head flow and should be paired with the head. But based on my research lift numbers are within spec.

As far as i know the duration is whats going to make all the difference on a turbo car. You can find tons of info on the big V8 cars, but mostly hear say and nothing of true intrisinic value.

Simplest ways to break down the cams.

Increase Lift = Global increase in airflow, across the rpm band.

Increase Dur = move tq curve farther right and make more peak power and higher rpm

If you choose to do both of those things, while keeping Overlap and LSA roughly the same as stock, you will get very mild gains, with little else changing. To get real gains though, the amount of lift and duration you'll need, means you'll have to get very creative with changing the center lines on the cams, using VVT tuning, etc.

With all that said, you really have to start looking at getting much more aggressive than anyone has done on this platform if you want real gains. All it takes is one look at some "Similar" turbo 4cyl's and you'll realize how little we have pushed the envelope with cams. The 4G63 head for instance, flows like shit compared to us, yet they're making more power at less boost in almost every instance... why? Because one of their first mods is a set of real cams. 99% of big turbo 4G's will be using a cam with a MINIMUM of 11.5mm lift on the intake side, yet nobody has gone much, if any above 10mm on ours, even though we can flow more than that.

With a mildly ported head, I've seen numerous times we are saturated at ~ .400"(10.16mm) of lift. Rule of thumb is to go 20-25% over than for you max lift which comes out to a .480" (12.192mm) max lift, minus your .008" lash and you're at an actual max lift of .472" (11.98mm).

Now that's far more aggressive than anyone has tried to run here, but funny enough... If you check out the best Evo cam to come out in a looong time, the GSC R2, designed specifically for the 4G63 2.3/2.4l stroker engines which only rev out to 8-8500rpm... They spec a relatively short duration of 236/236 @1mm (~232/232@.050), but have max lift of 12.1mm Intake and 11.9mm exhaust.

So... If I was building a 2.3l DISI, those would be the cams I'd want to use as a good base. I understand this will require upgraded springs/retainers/etc and put a lot of added stress on the timing chain/cam sprockets, but if I was doing it, I'd either stay stock cams which will support >700whp or I'd go all out with a cam that will make a big difference.

Just my thoughts.

Well said and if you pull the spread sheet that's why I am using the evo(4g63) as a comparison. I can look at delta all day but understanding the reason for the delta is what I am after. GSC is something I had thought to add but I will today. I need to call them to get some idea for a cam. I mean if you look at th Chang es it's fair large increase over stock.

time for the 2015 build thread i take it?

Any one else?

Can you recap your turbo setup and power/rpm goals real quick? Also, your willingness to upgrade valvesprings or not?

I've spent a lot of time working on a cam grind for my personal build/goals, but there's a very very good chance, you'd want something different.

Oh of course! The turbo currently is a gt4088r may be switching to a 6466 or have fp upgrade it later on. I am without a doubt upgrading the springs and retainers. I would like to see an effective rev range from 4000 to 8500.


What else would you like to know?