Ok I have been doing as much reading as I can find around here and am curious what everyone else has experimented with.

My setup last year was stock '01 ld9 with secret cams(installed straight up), this year I am porting the head and and putting in my HO cams.

By my math each tooth on the cam gear is 9.47 degrees, I know thats a big increment, but depending on valve events may help with spooling and power if adjusted accordingly. I know you can offset drill the dowel in the gear also for whatever amount you want. I dont have any specs on the HOs to compare to stock or base adjustments from.

So if anyone has any experience with advancing/ retarding cam timing on a quad or ld9 lets hear it.

Not saying that putting them in normally isnt good but advancing the exhaust a bit or retarding the intake could show beneficial for boost. I may just have to bust out the degree wheel and take some measurements for myself when i start putting it back together.

good deal on wanting to do this man... the HO cams were designed for an N/A engine so adjusting them out a bit for boost is definitely going to help some.

i do know that at 9 degrees (like you said, one tooth basically) advanced it basically kills an N/A LD9. dont know if it would on boost though...

from what i and others have found, the HO cams centerlines are near or at 108* INTAKE and 110* exhaust. if you could take some of the overlap out i think it would be beneficial for boost.

i hope mcmoney chimes in because he has actually dyno tested his adjustable gears and found gains with HO cams on his motor. i believe he found 7whp...



Edited 1 time(s). Last edited Friday, June 24, 2011 12:37 PM

Essentially with a turbo application you will want to dial out as much overlap as you can which is a huge help to building boost. Overlap allows the cylinder pressure to bleed out which hurts boost. I am running my new setup ay +3 exhaust and -3 Intake. To effectively move my powerband down I can do +2 -4 and to raise my powerband up I can do +4 -2 so effectively changing the cams in equal degrees after primary timing is met you can adjust and manipulate you powerband.

Here is a GREAT read that oldskool and I did to go after my issue with cam timing

Cam Timing





LE61T PTE6262 Powered

Just read through that and it helped reinforce my thought. My plan was depending on how far I can go and how much is needed, to at least advance the exhaust cam a tooth. If it can work out I may retard the intake cam a tooth. I have a few spare sets of gears so I may just offset drill a set for whatever degree I want also.

I am gonna start working on a design for a removable top half for the timing cover to change things easier. I know mcmoney makes one but thats too much cash for me right now. I gotta finish putting together the motor for my 98 z before I start back on the turbo car though.

The 98 is getting flat tops, secret cams, ported head, and LO intake. I may change cam timing on it to shift the powerband too.

In the ld9 cams list post I found that Zs Z noted the HOs have an overlap of 31* according to desktop dyno. Can anybody confirm this and whats an acceptable amount of overlap to keep the motor from being a complete dog out of boost?

It looks like one tooth on each cam may be a possibility as long as it doesnt kill my low rpm. +9.47* exhaust and - 9.47* intake= 18.94 overlap decrease leaving 12.06 overlap.

3°...not 31°. HO cams respond very well to boost at stock timings.




I have no signiture

Sorry, I just looked at the thread, and he measured it @.005" lift. It's generally more meaningful to measure @.050" though. I'm not sure where brad got that chart, but according to that, HO's have -8° overlap @.050" at stock timing...which I'm not too terribly confident is correct. I could have sworn the LSA was smaller for the HO's.




I have no signiture

courtesy of brandon blaga...

This is why I was wondering if anyone has actually measured the overlap because there is limited info anyway and its all conflicting.

I know they like boost at stock settings but I am just looking for the optimum spot for them, if stock is it then so be it.... I just want some *proven numbers.

ok then check out mcmonie's thread... he has dyno proven results on HIS engine with an adjusted ho combo...

I just looked at his thread and his adjustment that gained 7 whp was 2.5* retarded on the exhaust. Thats going the opposite direction of the general idea for boosted engines. That would be adding overlap, which is still under 0 degrees anyway but its still confusing.

Bringing back an old thread to possibly revisit this idea. I kinda dropped the ball on this because I popped a piston in my turbo motor. I haven't messed with anything in a few years and now I'm getting things going again. I was curious if anybody has come up with anymore info on the subject or proven setups with secrets or ho cams.

I think Chris Walters made 432whp on secret cams. We know over 500whp has been made on HO's.



FU Tuning