Garrett Turbos

[Pisobiker]

Then one small addition:

BE AWARE OF TOO HIGH RPM !

Inertial forces increase with the square of speed, so at TDC in the intake stroke inertial load on conrods (extension load) is maximum.
If you exceed max safe rpm for a given conrod it will break.

Usually, bent rods are the sign of too much torque applyed, while broken rods are the sign of too high revs.

Very last consideration:

Fatigue over conrods is another problem. Fatigue is the combination of a reciprocating load (extensive + compressive) for the friquency of it. This means that if a device can happily withstand an alternative load for lets say 10 millions cycles @ 5000 cycles per minute, it might be possible it will fail at less than half total cycles at double of the frequency.

As much as fatigue load is concerned, it is out of doubt a conrod used at higher loads @ high rpm will have a shorter life (which might still be several hundred thousands miles.....)






Marco

[Albert]

I gues I should put my Pauters ASAP.

I have drove my car yesterday and still works I will have to save it and till the time I put the rods in I will limit the distance driven on hi boost.

[diesel des]

Yep - my previous statement was a bit open-ended... It was in the context of Albert's engine pushing 1.8bar at high revs which must generate a lot more torque than 1.2bar at low revs.

If you've read my recent paper on 'turbology' then you'll know I understand the principles of torque and power.

I absolutely agree with you that it is torque which bends rods - not power - hence my confusion about Alberts boost profile. Seems to me it could bend a rod anytime soon - and at high revs too !

One question I do have for you is to share the source of your calculation which equates 400lbft of torque at 7000rpm to 533bhp ?

I must have missed that class


Cheers,

Paul

Formula i have is BHP = (RPM/5252) x Torque

So at 5252 rpm you have the same BHP as torque in ft/lb.

At RPM higher than 5252 you have more BHP than torque and vice versa.

Isnt that correct. Got me wondering now....

[diesel des]

Subject of conrod stresses was covered some time ago in this forum. Take a look here:

http://www.s2forum.com/forum/showthread.php?t=322&highlight=inertial

Marco

Great Thread marco !!!! That all makes sence

[S2central.net]

Formula i have is BHP = (RPM/5252) x Torque

So at 5252 rpm you have the same BHP as torque in ft/lb.

At RPM higher than 5252 you have more BHP than torque and vice versa.

Isnt that correct. Got me wondering now....

Woah Betty - were does that formula come from ?

I'm guessing its more of a rule of thumb than any hard scientific calculation. Will have to look at some plots to see if it vaguely works.


Paul

[S2central.net]

D'oh - looking at pumaracing now for some science and a history lesson in how the term horsepower was invented. Excellent - nice one Marco !


Paul

[audiman]

All I can say is that IF you bend a rod at high speed or low speed it could do a lot of damage. I was very luckly with mine, it only bent a bit, Steve H was less lucky as the rod touched the block. At worst the rod would come out of the block

If you want reliable BHP or torque then uprated rods are the ONLY way, as Des said, 1 misfire on stock rods would be game over.

[S2central.net]

I now consider myself educated. Brilliant, the 5252 number is derived from 33,000/2*Pi

Most excellent, now all I need is a rough guide for estimating how much torque is produced at given boost levels and I'll be even happier. Easily pleased I am...

Paul

[diesel des]

I now consider myself educated. Brilliant, the 5252 number is derived from 33,000/2*Pi

Most excellent, now all I need is a rough guide for estimating how much torque is produced at given boost levels and I'll be even happier. Easily pleased I am...

Paul

Numbers are great arnt they! god i sound like my old maths teacher....

So Paul do you agree that the torque is the rod buster, and if so what do you reckon of the GT30R on the stock bottom end with the boost held back in the mid range to hold the torque flat and then the boost increased at the top to keep the torque up where it would normally fall. What do you think is a safe torque?

I plan on using the GT30R i have on the stock bottom end for a while. Then when i bust that, i will build a 2.5L TDi blocked beast with the right rods etc.

[S2central.net]

Yep yep - I never disagreed that torque is the rod-bender...

I will look at the GT30R map tonight. Your idea is sound because a wide flat torque profile will produce the most linear power output. You'll want to keep torque safely below 550Nm in my opinion for the ABY/ADU rods. Quite what that means in terms of boost levels on the GT30R I have no clue yet.

I need someway to estimate torque values from co-ordinates on the compressor map with a known engine capacity.

I know that torque = P x A x L of course, where P is BMEP acting on the piston surface (of bore area 'A' and stroke 'L') but its the detail of calculating P (which we all know is proportional to boost) which has me scratching my head. Then there will be umpteen unit conversions ... Maybe its devilishly simple !

I frickin love this forum by the way - where else could you find a bunch of like minded folk who can exchange facts, theories and practical knowledge on these crazy cars of ours ?

Paul

[Jamo]

Paul I know you had a spreadsheet with these calculation in but it was locked to 2bar maximum, do you have that spreadsheet with the boost figure unlocked?

Also is quite interesting, when did Ford mags get the detailed? http://www.motorsport-developments.c...AF259.tech.pdf

[S2central.net]

All you have to do is unlock/unprotect the affected cells - theres no password. I can dig one up you get stuck...

[S2central.net]

Oh I have one here - already setup for a stroker circa 2bar max boost (no specific turbo in mind - you MUST check your compressor map).

I've got increased VE guesstimatewith a ported head. This one caters for water injection and toluene as well just for laughs. It does injector and fuel pump sizing as well...

[Jamo]

Wow cheers Paul, I'm just punching in some figures from a record stroker dyno plot running a 3076r and it's very close

[S2central.net]

Isn't this much more fun than talking about fecking tweeters and woofers ! Much more my comfort zone at least...

You'll note how I have three power estimate columns (different methods) there and I use the average figure to plot on the graph - and derive torque from. It has been a good ready reckoner for a number of turbo installs and greatly simplifies component selection even for novice users dabbling in the wonders of upgrades......