4AGE - Crank and rods

[306rwd]

I am sure this question has been asked many times so I apologise in advance.

What is the recognised maximum revs/bhp for the standard crank and rods. I would like to know the maximums for both the 40mm and the 42mm b/e journal crank.

Thanks

[4agte]

depends if you are going n/a or forced induction....

[Billzilla]

You can run 8000rpm all day, with the occasional blast to 8500rpm if you like.
If you know the crank doesn't have a lot of miles on it and has no cracks (unlikely) they're good for 9000rpm. Just make sure they have plenty of oil.
The rods are good for those revs as well, again just make sure the bolts are replaced every time they are undone.

[SEXY 16]

put a astra 16v in her lad

[306rwd]

depends if you are going n/a or forced induction....

Thanks, it is n/a

[306rwd]

You can run 8000rpm all day, with the occasional blast to 8500rpm if you like.
If you know the crank doesn't have a lot of miles on it and has no cracks (unlikely) they're good for 9000rpm. Just make sure they have plenty of oil.
The rods are good for those revs as well, again just make sure the bolts are replaced every time they are undone.

Does that apply to both the 40mm and 42mm crank and rods?

Thanks

[gixer]

I used crower rods, you can buy these for reasonable money, then you don't have to worry about it being a problem unless you pull HUGE rpm.

[Billzilla]

Does that apply to both the 40mm and 42mm crank and rods?

Thanks

Yep.
Best also talk to one of the best 4AG men in the UK though, Richard Macer from Hertfordshire.
01462-481660
Been a while since I used that number, I hope it works.

[ENKI]

Just a thought but ist torque more so than power that kills the bottom end of an engine so more rpm equals more torque thus rod through the block or piston through the head take your pick?!?!?!
So high reving n/a puts more stress on engine rather than low reving forced induction?
Listen to billzilla though i do not doubt his 4age knowledge one bit.

Nick

[Mr Revhead]

for a new prepped crank, 9500 is doable, but more for a race engine thats getting rebuilt or crack tested every season,

otherwise 8500 would be my suggestion.
99.9% of 4age failures are usually traced to lack of oil in the bearings

[Sam_Q]

is the crank more stressed in a boosted engine than an atmo? I thought the inertia of the piston outweighed the downward force of the pressure.

[306rwd]

for a new prepped crank, 9500 is doable, but more for a race engine thats getting rebuilt or crack tested every season,

otherwise 8500 would be my suggestion.
99.9% of 4age failures are usually traced to lack of oil in the bearings

I agree. Lack of oil has caused me to blow 2 engines in a year. This was after about 50 rallies of never even taking the cam covers off except for the occasional rebuild.

The next engine will be dry sumped.

[Sam_Q]

and why did this happen, oil surge?

[306rwd]

and why did this happen, oil surge?

Almost certainly, yes.

I have been using the same modified/baffled sump and pick up pipe (conversion to rear bowl) since 1995 with no problems. I have probably done 1000 forest stage miles in two different cars with the same setup. I am driving quicker now and with a morev powerful engine so I think I may be outdriving the baffled sump. Perhaps it has always been just within the limit.

I am definately going dry sump now which will cure the problem.

[Sam_Q]

do you think someone such as myself that would do some hard street cornering and a racetrack outing at times be well off by adding extra baffling?