so simple question... i have crower stag 3 cams from my allmotor enigne and would like to have a boost friendly cam like and ITR and/or gsr combo... in theroy u should be able to tune out some of the overlap.

rather stay with the crower casue the lift is awsome.. but i will probly have to go to my ITR's..

anyone have a rule of thumb when i comes to adjustable cam gears and tunning them for less and/or more overlap ...

i have 01' ITR cams, 95 gsr cams and b16a jdm obd1 (5speed cams)....i also wil be using my AEM trutime gears i have on my crowers

cam specs from crower http://www.crower.com/cat/impo...shtml

specs for Crower stage 3 (63403-2)
-Duration @ .050"
--Int- 263 mid
--Exh-255 mid
-Gross Lift w/1.55
--Int- 468 mid
--Exh-468 mid

spec for 01 ITR cams (specs from Crower's web site thats why duration is in INCH. also 01 itrs are same as CTR)
-Duration @ .050"
--Int- 240 mid
--Exh-232 mid
-Gross Lift w/1.55
--Int- 447 mid
--Exh-416 mid

i dont know the exact OVERLAP of these cams. i didnt get a cam CArd wiht my CROWERS and when u search for ITR overlap spec, everyone is talkign about dialing in more or less overlap...

i did search and found soem good info..just want people educated IMO....
https://honda-tech.com/zerothread?id=1333221
https://honda-tech.com/zerothread?id=1455063

plus theres a few more out there....

 

BUMP...forthe peps tat cant suff h-T at work...

 

First do you understand what overlap is? I will help you if you understand. You can take overlap away by adjusting it with a cam gear...but you are still dealing with duration and lift.
Looking at the specs that you are giving for the Crower cams...thats a really good cam for turbo. It has really good lift and duration...not to much and not to little.
From all the turbo cars I've tuned...they like more overlap. The Webcmashafts that I use are very similiar to the Crowers you have.

 

i do understand how overlap works....but i mis understand how overlap is bad for boosted cars...the spec came right from crower web site

 

from what is said crower stage three's have more overlap @ 0 +/- ADJUSTMENT...so


so crower stage three cams are good for boost

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by punkracer &raquo;</TD></TR><TR><TD CLASS="quote">i do understand how overlap works....but i mis understand how overlap is bad for boosted cars...the spec came right from crower web site
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I've read that before as well...I dont know for experience so I just simply dont know but I would like to know the true answer.

 

Overlap is the point in crank rotation when both the intake and exhaust valves are open simultaneously. This happens at the end of the exhaust stroke when the exhaust valve is closing and the intake is opening. During the period of overlap, the intake and exhaust ports can communicate with each other. Ideally, you want the scavenge effect from the exhaust port to pull the air from the intake port into the combustion chamber to achieve more efficient cylinder filling.

You need to degree the cam in first by using the cam card, then play around with the lobe centers (adjust cam gears). Retarding exhaust cam and advancing intake cam will give you more overlap and Visa Versa. Very confusing stuff.

 

Overlap is said to be bad for boosted cars because your exhaust mani pressure is always higher than your intake mani pressure (unless you have a gt47+ on there and a great manifold). THe problem with that conventional wisdom is that turbo Hondas love overlap - a 'turbo' cam with less overlap but more lift will pale in compairison to the opposite (NA cam). I would guess its because you have so much more exaust volume (and density vs the motor NA) that the exhaust would rather continue into a higher pressure zone than revert back at high RPM. Also since we usually use bigger/heavier WG's, it won't react lightning-quick. That means between intake events, the turbo pressurizes the intake more. Your boost gauge just measures the effective average PSI.

You have to understand a conventional OEM turbo motor is built with a small turbo, developes boost (and ex mani pressure) way down low, and doesn't see Honda-characteristic high rpm's. There are few, if any, other vehicles that are boosted after the fact by the owner. Volvo/Toyota/Nissan guys all have their factory boosted motors, and take hints from those. The Honda crowd makes relatively independant dicisions based on trial & error.

 

thanks...lol they explained a lil' of this theroy in the new honda tunning mag....wow its been so long since i talkd about four stroke enigne theory ...feels like i am back in school

 

yeah overlap isnt a bad thing in "moderation" with boosted setups people run some pretty aggressive allmotor cams with there boosted motors and have great results.

 

Bump....so i think i am going to stay with the stage 3's...