RPM Switch for VTC in GA16 w/ flat top pistons (no notch)
Hi! I have a RPM switch for active the VTC but my engine have a custom falt top pistons (not notch). My question is... have problem with the valve and piston clearance? The intake valves with VTC activated "crashed" in the piston...? I have OEM Cams, stock head, stock OEM head gasket...! Thanks!
* sorry! I speak a little english.
Since no one has direct knowledge, the old school way to check this was to assemble and insert plasticine or a putty in the critical areas and hand turn over to measure the clearance.
You could also check the all motor section, and re-post there. ask nicely, they might know. http://www.nissanforums.com/naturally-aspirated/
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1997 Sentra GXE w/195/50 15's and AD22VF, Tach, Halo's, Front seal, Rear SER Disc Brakes Soon to be sold
1997 S-ER 5 sp yea !!!
2003 Pathfinder SE 4WD
Ex- 2001 Sunny N16 RHD (N16 Nissan Bluebird Sylphy)
Are you saying they already crashed into the piston, and you want to stop the VCT from working?
Or that you're afraid they're gonna crash into the piston, and so you wanna turn off the VCT beforehand?
It runs off an electric solenoid, in any case, so disconnecting the solenoid will stop the VCT from engaging. However, that'll probably throw a CEL, and you'll lose top end power, but that's better than putting a valve through a piston. It's part 23796 on the below diagram.
Or that you're afraid they're gonna crash into the piston...
I want the VTC but i scare gonna crash the valve. I can do a manual test to check this? maybe advance +1 in the timing chain. (VTC intake sprocket). This is correct? Thanks!
I think better way to test this migth be (like IanH told) to use some material witch you can put in the cylinder from the spark plug hole and then turn out the engine by hand. after that you can measure the clearance betveen piston and valve from that materia you put inside the engine. Just take it away and measure how flat it is.
But to get correct results you should somehow activate the VTC when turning the engine.
- No-Pain -
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Nissan Almera (equal to Sentra) 1997 1.6 litres
Mods so far:
-Added disc brakes to rear
-All corners have got new springs and shock absorbers (monroe reflex)
-custom made 4-->1 exhaust manifold with 2" piping -Some cool kameleont painting
-Head work done. Porting, some valve job (lightening, cleaning and polishing). Intake- and exaustports on the head totally re-designed and grinded.
-Some gauges: oil temp, oil pressure, fuel pressure, meter, lambda and external rev. meter with change ligth
-Free flow air-filter (calculated intake pipe lenght) with CAI.
-Lightened battery, moved to back
Sounds like to me you wanted the advantage of increased compression with pistons that have no reliefs. However this is telling me a possible stoke modification.
I did this to my 3.4L DOCH GM LQ1 with custom hyperetics and had to have the cams custom ground. This made my LQ1 a interferance engine so if the belt broke I would have to replace several valves.
To me it sounds as if a head shim may make the valves clear duration, however not sure what clearances you have.
Adjusting timing may not fix it as then the other end of the spectrum may collide timing wise after the power stroke effectively decreasing RPM limit. If you have to adjust timing then would it not make a flat top piston a waste of time as the valve would open late and close late. In this case it seems the valve would open full atTDC to collide.
Also to me I would get custom pistons that had reliefs but made in such a way to decrease piston to head clearance but maintain relief depth accomodated by head decking and block planing. We are talking few thousandths so the advantage of removing reliefs all together may not yield any practical results without other modifications.
Last edited by Juglenaut : May 11th, 2008 at 01:02 AM.
The advanced +1 in the Intake sprocket is simulated the VTC activated. I realice the test this saturday and the valves no touch in the pistons, good for me! Thanks!
to my knowledge we do not have any interference in the piston to valve clearance, so you would not have to worry if the chain broke. the engines with issues are the Honda B18C or B16A motors or H22. the belts would break and good buy to the valves!!!
All you are doing is moving the vale timing a slight bit with the VTC a few degrees the same as the old honda can timing gears, but with electronic. The VTC in the GA16 opens at about 3,000 rpm. then retards it at I think 5800?? not sure on that one, but JWT advances the cam at 6200 I believe to open the cams up and let the air flow and we get like 25 HP boost at the top end. not sure on the torque because you are at the peak and torque usually falls off, bur Nissan engines pull linear in the curve, unlike the honda 170 HP and 120 Ft/lb torque!!!
Chris 92 classic
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this is the problem!!!!
Linear Mode
