Holset vs. Other turbos

[chipsenter]

Yeah while u have everything out u change em at the same time.

I remember my stock pistons the first time I opened the engine for upgrade reasons.
They almost had a shape of new ! the car had ran 230.000km when I did it.
Great condition only clean em up and change pins and rings and put back .


GO 4 It

[Jcarrick]

Thats awesome! What about main and rod bearings? Change those too? Or are the stock ones ok?

[GazzaG60]

change the rod bearings. its box off for the others. i left mine.

i skimmed the piston, fitted the original rings back on, and fitted the WEIGHT MATCHED scats.

top tip and i always do this now. order an ARP ring compressor. they are one size only but weork a dream. far better than than the clamp ones.

[Jamo]

change the rod bearings. its box off for the others. i left mine.

i skimmed the piston, fitted the original rings back on, and fitted the WEIGHT MATCHED scats.

top tip and i always do this now. order an ARP ring compressor. they are one size only but weork a dream. far better than than the clamp ones.

Yep I borrowed one from a forum member made life very easy

[GazzaG60]

i have 2. 83mm which is the 2l 16v size i used and s2 std bore.

i fannied for a bit with an adjustable. complete ham-shank

[TurboTransAm]

Just a bit of Holset feedback from a guy who has used one (and also a question).

The HX40 is awesome. It's bullet proof, easy to find and cheap. It's also very, very adaptable as I ran one on a mild 383ci Chevy V8 (that's just over 6.2 litres). It was in fairness a little small although it had a 22cm turbine housing which allowed it to breathe within reason on the V8. The 60mm compressor came on boost instantly and pulled hard to around 5000rpm. For the money Holsets are awesome turbochargers and anyone that says you needs to spend over a grand on some brand name turbo reads too many glossy magazines.

Now for my question... and this one has bugged me since the day I joined this forum. How does 'low end torque' bend rods when 'high end torque' is considered safe?

Here's the deal as I see it - Torque is a measure of twisting force. 200 lb/ft of torque has exactly the same twisting force at 1000rpm as it does at 8000rpm. So how can x amount of torque which is completely linear throughout the rev range bend a rod at 3000rpm but not at 6000rpm?

If you'd said breakages were more likely at higher rpm I'd be first to agree. The ever increasing velocity of moving-parts changing direction as the revs increase obviously stresses parts like rods, mains and bolts. Anyone that knows anything about making horsepower will tell you that 'revs' kill engines (and detonation of course) - not torque.

I run probably 700lb/ft of torque @ 3500rpm (GT45) through my V8 on a cast crank and some cheap aftermarket rods with no problems at all. However, take that motor to 7000rpm and it'd probably rip itself apart. So what makes I5 Audis the exception to the laws of physics?

[chipsenter]

Really good Point there U might not get ur answer u looking for mate hehe.
I asked my self the same the other day. ?

You should serious bolt on a HX55 or 60 on your Chevy , damn the beast would turn in to a monster

/J

Just a bit of Holset feedback from a guy who has used one (and also a question).

The HX40 is awesome. It's bullet proof, easy to find and cheap. It's also very, very adaptable as I ran one on a mild 383ci Chevy V8 (that's just over 6.2 litres). It was in fairness a little small although it had a 22cm turbine housing which allowed it to breathe within reason on the V8. The 60mm compressor came on boost instantly and pulled hard to around 5000rpm. For the money Holsets are awesome turbochargers and anyone that says you needs to spend over a grand on some brand name turbo reads too many glossy magazines.

Now for my question... and this one has bugged me since the day I joined this forum. How does 'low end torque' bend rods when 'high end torque' is considered safe?

Here's the deal as I see it - Torque is a measure of twisting force. 200 lb/ft of torque has exactly the same twisting force at 1000rpm as it does at 8000rpm. So how can x amount of torque which is completely linear throughout the rev range bend a rod at 3000rpm but not at 6000rpm?

If you'd said breakages were more likely at higher rpm I'd be first to agree. The ever increasing velocity of moving-parts changing direction as the revs increase obviously stresses parts like rods, mains and bolts. Anyone that knows anything about making horsepower will tell you that 'revs' kill engines (and detonation of course) - not torque.

I run probably 700lb/ft of torque @ 3500rpm (GT45) through my V8 on a cast crank and some cheap aftermarket rods with no problems at all. However, take that motor to 7000rpm and it'd probably rip itself apart. So what makes I5 Audis the exception to the laws of physics?

[Jamo]

Just a bit of Holset feedback from a guy who has used one (and also a question).

The HX40 is awesome. It's bullet proof, easy to find and cheap. It's also very, very adaptable as I ran one on a mild 383ci Chevy V8 (that's just over 6.2 litres). It was in fairness a little small although it had a 22cm turbine housing which allowed it to breathe within reason on the V8. The 60mm compressor came on boost instantly and pulled hard to around 5000rpm. For the money Holsets are awesome turbochargers and anyone that says you needs to spend over a grand on some brand name turbo reads too many glossy magazines.

Now for my question... and this one has bugged me since the day I joined this forum. How does 'low end torque' bend rods when 'high end torque' is considered safe?

Here's the deal as I see it - Torque is a measure of twisting force. 200 lb/ft of torque has exactly the same twisting force at 1000rpm as it does at 8000rpm. So how can x amount of torque which is completely linear throughout the rev range bend a rod at 3000rpm but not at 6000rpm?

If you'd said breakages were more likely at higher rpm I'd be first to agree. The ever increasing velocity of moving-parts changing direction as the revs increase obviously stresses parts like rods, mains and bolts. Anyone that knows anything about making horsepower will tell you that 'revs' kill engines (and detonation of course) - not torque.

I run probably 700lb/ft of torque @ 3500rpm (GT45) through my V8 on a cast crank and some cheap aftermarket rods with no problems at all. However, take that motor to 7000rpm and it'd probably rip itself apart. So what makes I5 Audis the exception to the laws of physics?

Your thinking of peak figures and not rate of change.

Because it's the change of torque at low rpm you are going from 0 to low force being exerted on the rod to a sudden impact of higher torque. for example say got from 100 to 600nm in one instance

At high rpm the engine is already making torque and the change of torque is more gradual through the rpm actually tends to decrease as peak torque is when the turbo comes on full boost.

[GazzaG60]

thats it rate of change.

heres another example. subaru

an impreza will blow 3rd in a box no worries due to small turbo low end torque spikes. the rotating mass is slowly moving then given a shove.

another fron engine mount on a corrado G60. with a smaller pully the rate of change to only say 200lbsft is enough to snap the front engine mount.

[A80Avant]

gary you have pm!!!

[TurboTransAm]

Your thinking of peak figures and not rate of change.

Because it's the change of torque at low rpm you are going from 0 to low force being exerted on the rod to a sudden impact of higher torque. for example say got from 100 to 600nm in one instance

At high rpm the engine is already making torque and the change of torque is more gradual through the rpm actually tends to decrease as peak torque is when the turbo comes on full boost.

I can understand this as a point however it doesn't really hold that much water. Anytime an engine moves from 0psi to say 15psi+ (for a tuned engine) the torque will at least double regardless of where in the rpm range it occurs. Generally speaking certainly within the mid-range, the higher the rpm of the change the greater the amount of torque being multiplied. Often this can occur within a very narrow rev band or a fraction of a second. So whether that band is 3000-3500 or 4000-4500 seems immaterial.

I appreciate what you're saying about the turbo hitting peak boost at peak torque so the 'boosted torque' up the rev range although multiplied is actually becoming progressively lower. However, what worse 'sudden impact of higher torque' could you present to a set of rods than having peak boost occur at peak torque? Surely this is precisely what the doctrine suggests we avoid!

Look at it this way. If you have 200ft/lb @ 3000rpm and you add 15psi by 3500rpm you're likely to be in the 400lb/ft area within 500rpm. However, in another scenario let's say you start adding boost at 4000rpm beginning at 250lb/ft - if you've added 15psi by 4500rpm you're likely to be running 500lb/ft within 500rpm.

The figures are not supposed to be clinically accurate but thats how the relationship between boost and torque seems to work. We can splt hairs about airflow, back pressure etc but in reality this is the nut and bolts of it. Oh and this isn't personal with anyone, nor do I profess to be 'right' - I just think it's time we had some evidence based upon physics (either way) rather than just assuming 'low rpm torque bends rods'. Maybe it's one for Mythbusters.

[GazzaG60]

im no scientist. im an it manager.

all i can go off is personal experience. i have seen well into double figures subaru's breaking a gear due to the low end torque spike. usually not on td04 but tdo5. i have used bigger turbos and not broken due to, i also believe rate of change.
i have seen lots and lots of G60 with ripped out front mount and snapped mount bracket or even snapped 02 wiring due to stretch from mount killing low end.

[Jamo]

If you wish to believe on this being a myth that's fair enough.

[GazzaG60]

dont think its that jamo. think its the explanation for the issue.

like i say in no metal tensile expert.

i know what a bent rod, snapped mount and teeth on gearbox sump plug is though and how much it costs to fix.

[chipsenter]

Anyway..

Why use a bigger turbo than its really necessary ? a decent RS2 upgrade work stock 315 hp , after a exhaust upgrade, chiptuning, even wg spring (not necessary) u will hit around 350-360 hp that is not a problem for this engine . Call it rod bender whatever , this is just own experience though . Why do all Chiptuners etc sell the product showing 350-370 hp then. Only to bend rods ?? hmm.. It must be a safe way to tune the engine to these figures to sell the product , agree ? ? but ofcourse the accident can happend even under stock figures to .. all engines is unique .

Have a great easter holiday guys

/J