Thread: Thoughts on a full race motor setup (Turbo Posts)

Yeah exactly thats what i was asking. So the high lobe overlap is no big deal for my turbo app. But the low lobes is where the overlap comes into play negatively. I get it. Thanks for all your help. I think that will be alot better bet than degreeing the cams that much

14psi of boost on that graph I posted earlier.
Correction, it says it is a ka24de with cams and stock bottom with a gt30r, not a 3071. It looks like an SR powerband to me though, right?

here is another graph.





From the full-race site. Hopefully I get decent results out of the 3076r. I want to peak HP before redline and see the power start dropping off.

There is no point to use Oil pressure to lock the lobe in all the time if thats what you want. Take apart the rockers and mechanically lock them in place.

If you are changing your cams at 5000rpm on a turbo setup then you are loosing power. Hands down. I do agree with you by using the large lobe for spool, but im not sure what you think this has to do with overlap. In theory you may want 0 overlap on a forced induction motor but in the real world with say a GT35R a set of N1's will make more power than a set of VET cams. Thats not an opinion, thats a fact.

Honda or Nissan motors both respond the same way with boost and Variable valve lift. It takes exhaust flow and heat energy to spool the turbine. Now if you switch your cams at say 5000rpm and have a smooth transition you may think thats the best for power, if you switch the exhaust at say 3000rpm, you have have a slight dip in power for 1-200rpms but you will spool much much faster because of the area and lift of the large lobe. The dip in power comes from the exhaust valve opening earlier but you are allowing higher flow of gasses. I have done a couple VET setups and with the sr16 cams you can switch them as low as 2600rpm to make a faster spool. sure, now you think that your going to be on the big lobes all the time and will suck for gas mileage and noise, but do what I do. I put in a Full throttle switch on the Throttle body but depending on the power band and how the turbo spools i'll set it differently. With the Hondata K pro on the K20/24 setups you can set the Vtec to engage on different RPMs and at different throttle positions and manifold pressures. I have done similar with AEM and the Apex Power FC for the S14/15. I still use an external RPM switch such as the MSD or launch control module for VVL to kick in at X RPM no matter what. Then you need to dyno the car at various throttle openings, 20,40,60,80,100% throttle and overlay the curves. You willl be able to see where the power starts coming up hard and you will have a point to START WITH for setting your VVL. Then I will usually set it about 1000rpm's lower ( no lower than 2500rpm though) and do the same thing. By then you can usually figure out about where to set the cams for full throttle Low RPM threshold, and also for partial throttle, where the power really starts to come on hard. Then set the TPS switch to close circuit at that throttle point to ground the relay for the VVL.

So you can have the cams to engage at 5000rpm no matter what throttle position is. Then say if fastest spool and power is at 3200rpm, you can have a separate switch on the Throttle body to kick in at partial throttle ( say 40%) and so below 40% throttle the cams will not kick in until 5000rpm, but below 40% they will kick in at 3200rpm. This may sound complicated but its actually very simple.

Another reason I do not like the large lobe on at idle is because there is now less power at idle so it will take more fuel to keep it idling, fuel mileage will be less, it will be louder, and you are robbing the motor of oil flow at lower RPMs

-Ted

I am confused... how does a N1 cam make more power than the VET cams? I can see that being the case on an 11000rpm motor, but for a street driven car I am putting my money on the VET cams. Higher lift, lower duration. A lot less overlap. I guess there is only one way to find out.

ok
if you lock in the ex cam, you can get a set of adjustable timing gears at set to -10 +10 (although i do recommend playing with the timing actually on the dyno for best results). With these cams setting you will be 0 deg of overlap when the intake is on low lobe then 28 deg of overlap when the intake kicks over to high lobe.

IF you actually start to play with larger more efficient turbo setups and do more research yourself and mess around a lot on the dyno you will learn a lot. I am not talking a small turbo setup here, i'm talkin GT35R ish here



Again, i'm not sure why you are so worried about overlap. Put a GT30R car on the dyno and start with the cams at 0. std sr20ve cams. then start messing with the cam gears and end up at -10 IN and +10 Exhaust and print out the dyno sheets of what the power curves are. Make sure to save in the file name what settings you are at. -10 +10 may have less overlap but it will make less power.

-Ted

ok you wouldn't have both the low lobes on at idle as thats just inefficient, and the amount of overlap they both have would be just stupid.

I am not saying switch your cams earlier to help with spool, as the sheer amount of overlap on the big cams would cause a huge dip in power, so you are running cams specs designed for higher rpms, which is not what we want to do.

But locking in the ex high lobe i think is beneficial as you can manually (with ajst gears) take out 20 deg of overlap (it might not work best at -10 +10, it might work better at say -3 +17, but its still 20deg of overlap being taken out)

so you will still run the low intake lobe and switch where power comes in best.

Now individual lobes better set up for turbo will still be better than this set up. But it is a fix to a couple of problems caused by the sr20ve cams, i.e overlap of the high lobes and it does mean you will run more lift in the middle of the rev range.

Problem with the ve cams for turbo apps imo is you have a low ex lobe that is restricted by lift in its high rev range and a high lobe that is inefficient at the lower part of it rev range due to excessive overlap. Which basically means you have no good cam to use in the meat of the rev range.

so by locking in the ex lobe you can take out 20deg of overlap once the cams switch, moving the power curve of the high lobes to the left. S this is better for midrange.

Sure by removing the low exhaust lobe all together you will robe a little down low and off boost due to running a 268 deg cam at idle, but the gains in the midrange will be much better on lightly tuned set ups because of the reasons mentioned and it will help solve reversion problems when running log manifolds.

yes i do agree that with with a big turbo and high flowing exhaust manifold the overlap will probably make more power.

But ashton wants to run a log manifold, and i doubt it will in his case. However he will be running a t3/t4 i thing so thats a decent sized turbo depending on what rear wheel is in it. Maybe an investment into a tubular might be a better alternative. But i understand he wants to cap power at around 300whp, i dont know why this is?

the set up i mentioned will be a solution for those running into reversion problems due to too small turbo or restrictive manifolds, becuse they want to keep a responsive set up

When i tune my car i might, just for fun to see how the power shifts. Although you will gain more power with 0,0 you will defiantly gain more midrange with -10 +10

This thread has reached kick as* status, thanks so much for sharing all this info. You know who you are. Oh, and thanks for getting along. We haven't had a thread like this in a while...

Got a few pages of notes out of this stuff, keep it coming.

Dudeman