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Discussion Starter #1 (Edited)
Advancing exhaust cam in 3vzfe to reduce cam overlap for boost Turbo Project

The 2vzfe, 3vzfe and 4vzfe v6 engines apparently have 12 degrees of overlap. The exhaust cam in these engines are driven by gears connecting both cams. Has anyone tried to advance the exhaust cam which should be fairly simple as the exhaust cam can be turned one teeth on the gear counter clockwise I think relative to the intake without removing the intake cam or interfering with the timing belt cam gears. My novice thinking has to do with incorporating boost. Has anyone thought of this or attempted it and the results? My basic maths is telling me that one teeth adjustment can reduce the 12 degrees by 4 degrees to about 8 degrees given that the cam interlocking gears have about 40 teeth(Will check). This exhaust cam advance may reduce under hood temps, wasted fuel, give more low end torque and make it more boost tuning friendly for upper rpm goodness.
 

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Honda-Tech White Ops
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I doubt youll have any issues leaving timing alone and boosting.


How much CFM do you plan on shoving in there?



This going to be a twin turbo or a single jingle?
 

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Discussion Starter #3
Was planning to boost the a 3vzfe but its overheating so I replaced it with a 4vzfe that I had on the ground which was originally in the car. Hoping the internals are good. I am using 2jzge JDM map ecu with MAP sensor which worked on the 3vz. This version 2jz ecu (1993 from Crown I think)had the same pinout and I just has to wire the map sensor using some of the MAF wires from the 3vz harness. I swaped in the 4vzfe and trying to start it right now. I am planning on using twin scroll t04b running each bank on either side of the turbine with custom piping, 2jzge ecu and injectors(330cc), aeromotive fpr, intercooler, SAFC 2, external gate with max 5 psi boost spring and maybe stick with the 10 degree base timing and stock 2.5" exhaust. I don't want to cross the 250 whp mark as I hear it's not good for the transmission although I already have an additional trans oil cooler installed. Want to stay reliable.
 

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Discussion Starter #4
To give an update.. The engine started fine with the turbo but the tranny torque converter apparently isn't aligned properly and the car isnt moving so will have to unbolt and set back..hopefully no damage. Fabbing custom exhaust up pipe and downpipe was a pain - still sastified with my effort. Haven't seen any turbo v6 using this setup. trying to upload pics..
 

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Honda-Tech White Ops
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I havent been in this forum for a while..


But 300cc injectors in my opinion are too small for the CFM that turbo is going to move.


If going for all out power, Id be looking to 800cc as not to max out the duty cycle.
 

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Honda-Tech White Ops
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^^^

he probably either figured that out by now or blew it up already..


Been a while since he posted
 

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Discussion Starter #9
The engine started and was running lean indicated from the wide band I had, but. unfortunately I damaged the transmission when I reinstalled it when the shaft did not set properly in the torque converter. I have to save money to buy a next transmission so car down for the while and never driven with boost. I was thinking of wiring a boost switch with a relay with the TPS to trigger open loop for tune under boost. Was thinking 330 cc injectors will be good for 250whp on the 2.5l and the laggy turbo will bring boost on when the engine is in open loop making it more tuner friendly. What injectors should I get?
 

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You'll want at least 487cc injectors to reach 295bhp @ 43.5psi using no more than 80% duty-cycle. Otherwise you'll risk overheating the injectors and/or going lean and blowing headgasket. Make sure your fuel-pump is rated for at least 103-lph @ 43.5psi.

Also, reducing overlap for boost is an outdated idea. With modern more efficient turbos without a lot of exhaust backpressure, air-flow through engine faces the same helmholtz-resonance tuning effects as NA. So you'll still want lots of overlap, medium lobe-centres, and late intake-closing for high-HP production.
 

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Honda-Tech White Ops
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^^

Not only that, Factory cams barely have ANY overlap in factory settings. And if it had a little, I doubt you'll be pushing boost out the valves that would cause issues.
 
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