With a fully balanced engine, std comp, all pistons/rods same weight, and std cams/lifters, how high can you safely rev a YB engine ? 7000rpm or can you go to 7500rpm ? Turbo is a T34 0.63 and Siemens 55lb injectors.

Any input welcome !

 

8k standard quite safely, IF engine is in good condtion

 

7800 imo, you get lifter issues around 8k

 

low comp with standard everything else, T34 and greys did 8250 ofr a year and a half of total death without any bother.

 

wouldnt go no further than 7500 unless u put upraed springs in ! but why it needs to be reved that hard on a t34 is beyond me mate

 

I doubt the valve springs would cope with 8k.

 

shouldnt get lifter issues on a t34 at that rpm t4 yeas but not a t34

 

valve bounce anyone

 

Well I have 4.44 diffs and 16" wheels so it would give some more range in the gears to rev it to 7000 or max 7500 rather than 6500. And I think the 0.63 T34 is still good at 7000. Obviously not as good as a T4 of course, but still enough.

 

ah ok matt then get some reyland uprated valve springs to be safe and jobs a good one

 

how does a different turbo change the level of rpm a hydraulic tappet can safely run?

i wouldnt fancy any of my ybs over 7800, without solid lifters

 

oh boy did i know this reply was coming

the volume of air is greater plus higher pressure run usually will collapse the hydrohlic tappet hence using solid lifters ! dave (madyum) suffered this issue on his last run at brunters using standard lifters

 

i assumed you were talking about cam choice, as this also makes a huge difference

 

never mentioned cams as he states standard everything hence my reply james

 

even on a t34 i was loosing power at the end of session on hydraulic tappets at 7500....

 

but YOU mentioned T4.... and who runs a t4 on std cams?


you said you may get an issue on a t4 but not t34.....maybe thats also due to cam choice?

 

A turbo has no awareness of how fast the engine is turning.. all it knows is airflow..

 

With a 0.63 exhaust housing or smaller ?

 

.48 mate, it was quite noticable...i guess id lost lots of lift

 

Yes, but as I have a 0.63, surely there won't be a real major loss ? 0.48 is understandable

 

plenty do james as there are those thsat believe a standard cam are good lol

again matt stated standard cams

that turbo will not cause lifter issues's thats why i suggested valve springs

 

The bottom end will take more revs than there is any point going to on that setup.

Lifters and springs will start to give you issues as you approach the 8K region.

 

Yes so will only change the springs then. Good news Will really need these extra rpms. Thanks everyone for the advices

 

i have uprated springs but oem hyd tappets and 7800 rpm has been no bother.

 

just be prepared to be disapointed with your power output on hydraulic lifters at the end of a hard session, even more so at high rpm....


imo

scooby slayer, i also run mine at 7800, on hyds...i hope it will be ok,otherwise i willl convert to solids....

 

Yeah if you keep it up at those revs it will be rattling its tits off at the end of a track session as the oil thins out, as it will knock the hell out of the lifters.

 

thats exactly what i found chip.

if you rev it high, you end up loosing so much lift /power,
you may aswell have knocked 500rpm off, and kept it stable, at the end of a session it would have more power, especially on a t34 which makes good low down power

i dont hold out much hope for mine tbh
and nomatter what turbo i would never take hyds over 7800 as you said its more due to heat and oil that causes them issues, they sound like they are empty

 

my limit is 7800rpm double valve springs and standard lifters

 

well at least 500 people started that way!

 

yes at 200bhp

i dont really see why people would chose a t4 for that