I have finally finished my project on the 2uzfe twin turbo landcruiser after years of testing. made good power on dynodynamics [email protected] bar@7500rpm on 93 octane. the problem is the life of the valves. tried stock valves and supertech valves. all failed after 5 -6 races. they start to tap and suddenly car will stop. we took it to the garage and disassemble the engine to find that always one pistons will be severed damaged because of the contact of the valves. any experts who can solve this ? . what could be wrong ?. I use stock retainers and single valve springs which are good for 9000 rpm. I don't have any kind of problems like overheating or anything else. its only the valve scenario which keeps repeating again and again.
2uzfe twin turbo
- Thread starter thalj
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The 1UZFE EGR Delete Kit is available for sale here.
spf_lexus
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Thats one mean landcruiser. I was about to mention the possibility of the VVti tuning causing the interference. Since contact only occurs on only 1 piston that rules VVti out.
If you are using high lift cams, would it be possible that the valves are contacting because of tight valve-to-piston clearance coupled with heat expansion following a few pulls?
Also do you know how much spring seat pressure you're running? OEM 1uz valves are notoriously soft. 45lb per spring. I suppose float could be the culprit of stock spring pressure is being used.
BTW do you have any vids of this beast in action?
If you are using high lift cams, would it be possible that the valves are contacting because of tight valve-to-piston clearance coupled with heat expansion following a few pulls?
Also do you know how much spring seat pressure you're running? OEM 1uz valves are notoriously soft. 45lb per spring. I suppose float could be the culprit of stock spring pressure is being used.
BTW do you have any vids of this beast in action?
its a non vvti . I was in the garage just now looks like 1 valve was bent on cylinder number 8 on the intake side. could miss fire cause that ? cause I hit hight boost yesterday when I was racing a modified Nissan r35. my car misfired then I herd a weird knocking noise and the car stopped and wont start again.
spf_lexus
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A misfire can cause all sorts of damage however obvious piston to valve contact makes me think valve float. Did the misfire occur at high boost AND high rpm? One thing to keep in mind is that boost will have an opposing force to valve seat presure. For instance, 100lb seat pressure with 20psi of boost will drop overall pressure to roughly 80lb. High boost + performance cams + high rpm + conservative spring pressure = possible float. Lastly, it is possible that a single valve spring may be damaged (cracked at its base) or is exibiting lower pressure than the rest which can explain why a single piston is taking the abuse.
Can you post some pics of the damage?
Can you post some pics of the damage?
lill daddy
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And some pics of the car itself? Sounds like one hell of a ride!!
I forgot to take pics but here is what happened. exhaust valve is broken and one intake valve got bent. piston got a lot of beating. lucky my bore is still fine. I just sent the head to make new seats. all other cylinder and valves are fine. I think because only number 8 cylinder was having a misfire this happened.
turboandrew
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That's really strange to see a bent valve from a misfire. I wonder if somehow the timing belt is stretching or the connecting rod has an issue. What pistons and rods did you go with? Was the block decked or the heads milled, which would reduce the clearance between the valves? What compression ratio do you have? Are the cams stock?
je pistons. pauter rods. didn't deck the block or head. 8.5 compression and high reving cams [email protected], .356 lift
XR8tt
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A slightly bent or bouncing valve WILL cause a miss big time..
Come on guys think about domestic motors !!!
Push-rods just do it at much lower rpm...Before rev limiters, EFI..
Boost + sq inch of valve is against spring pressure..As said..
Come on guys think about domestic motors !!!
Push-rods just do it at much lower rpm...Before rev limiters, EFI..
Boost + sq inch of valve is against spring pressure..As said..
spf_lexus
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When the valves come out, take a look at the valve guides for signs of wear and excessive heat (bluish color). If the guide I.D. deforms or is inconsistent with neighboring guides, a stuck valve can occur resulting in the piston/valve contact.
XR8tt
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Go through spring tension V cam specs keeping attention to coil bind etc . Bigger engine using going to improve valve train issues. Are bearing clearances ok ? A run bearing can close piston to valve clearances .
turboandrew
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How high were you revving the engine? Where did you get your cams? Also, did you change your intake manifold to something custom? Sorry, these questions don't really help you situation; I am just very interested in your build.
XR8tt
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Cam re-ground ? What was total lift ? Spring pressure at seat and over the nose ??
What valve spring where used ??
What valve spring where used ??
