3 registered members (slicer, Mags, Rosso),
240
guests, and 2
spiders. |
Key:
Admin,
Global Mod,
Mod
|
|
Forums69
Topics113,621
Posts1,341,294
Members1,807
|
Most Online731 Jan 14th, 2020
|
|
|
Re: 20VT- BHP limit???
#43472
07/02/2006 09:35
07/02/2006 09:35
|
Joined: Dec 2005
Posts: 3,694 Midlands
MCMike
Club member 2095
|
Club member 2095
Forum is my job
Joined: Dec 2005
Posts: 3,694
Midlands
|
I think most of the cars running 350 odd bhp are already running replacement or rebuilt engines, wheras the 'lightly tuned' cars are generally those running on the original engines, which are in some cases nearly ten years old. an interesting thread, and vibes i'm picking up are that an FMIC would be a good move.
1972 Triumph Stag 1984 Alfasud TI 1999 Fiat Coupe Turbo LE 2005 350Z
|
|
|
Re: 20VT- BHP limit???
#43473
08/02/2006 05:18
08/02/2006 05:18
|
Joined: Dec 2005
Posts: 286 Germany
Stichl
Making a profit
|
Making a profit
Joined: Dec 2005
Posts: 286
Germany
|
I think, that blown pistons mostly are caused by wrongly mapped cars. Because of too high exhaust temperatures Aluminium will lose stability dramatically - the beginning of the end of pistons... To the rods - investigations in Germany showed that the quality of the rods is fluctuating. Thus rods could be found with visible forge-defects... Nevertheless Fiat mounted these inferior parts. A good idea particulary for older rods may be shot-peening -this method definitely will show damages / cracks with a positive effect of higher durability.
Juergen
20VT coupegrale 4x4
|
|
|
Re: 20VT- BHP limit???
#43474
08/02/2006 06:15
08/02/2006 06:15
|
Joined: Dec 2005
Posts: 3,158 Near Reading
JohnS
I need some sleep
|
I need some sleep
Joined: Dec 2005
Posts: 3,158
Near Reading
|
The rods weakness is torque and quality of manufacture which is *very* variable in my own experience. The pistons weakness is the ringlands which are visiually less substantial than a lot of comparable turbocharged engines' cast pistons.
If you're tuning your car you have to either determine what your safe limit is or be willing to take the consequences of going over it. Since there isn't a great deal of empirical evidence all you can say is 400BHP and 400lbs/ft is almost definitely too much. 360BHP and 360lbs/ft is only 10% less so is probably around the range of limit where you must be willing to take the consequences, and anything below that is much more subjective.
If I was starting again tuning a std 20VT I would put forged pistons and rods in at anything over 330-350BHP as there are other benefits to them too, like they weigh a good deal less (>20% less), they are balanced to within 0.1g compared to Fiats +/-5g and they can take a little more abuse without breaking if nothing else. And given that the bores on the turbos tend not to go oval much it means that even a relatively high miler can chuck them in safely (after inspecting the bores) unlike on some other engines.
Former low boost hero - 616BHP@1.5 bar. 2.4 20VT RIP
|
|
|
Re: 20VT- BHP limit???
#43475
08/02/2006 07:31
08/02/2006 07:31
|
Joined: Dec 2005
Posts: 991 Drakelow
Jamiepm
Club member 1989
|
Club member 1989
Enjoying the ride
Joined: Dec 2005
Posts: 991
Drakelow
|
Does anyone know what is deemed the peak EGTs we should see on our engines??
Jamie
She's alive!
|
|
|
Re: 20VT- BHP limit???
#43476
08/02/2006 07:34
08/02/2006 07:34
|
Joined: Dec 2005
Posts: 10,728 N.E Scotland
mattB
Club member 6
|
Club member 6
I AM a Coop
Joined: Dec 2005
Posts: 10,728
N.E Scotland
|
I read the other day, that 900-950 was the most you should get, before you start getting into trouble.
Death-rattle-tastic
|
|
|
Re: 20VT- BHP limit???
#43477
08/02/2006 07:41
08/02/2006 07:41
|
Joined: Dec 2005
Posts: 991 Drakelow
Jamiepm
Club member 1989
|
Club member 1989
Enjoying the ride
Joined: Dec 2005
Posts: 991
Drakelow
|
I've read similar figures, but then they also referenced overfuelling causes the EGT to be higher when I would have thought lean running would give higher EGTs Jamie
She's alive!
|
|
|
Re: 20VT- BHP limit???
#43478
08/02/2006 08:44
08/02/2006 08:44
|
Anonymous
Unregistered
|
Anonymous
Unregistered
|
well just from my nautical days when i used to work on 6000bhp diesels that had individual fuel pumps if we had low exhaust temps on one cylinder we used to put that fuel pump on that cylinder to full fuel to get the temps back up so sounds like too rich gives high exhaust temps Kev
|
|
|
Re: 20VT- BHP limit???
#43479
08/02/2006 17:23
08/02/2006 17:23
|
Anonymous
Unregistered
|
Anonymous
Unregistered
|
Jamie, when I've been reading about EGT's almost all the information on the web is from diesel engines, aiplane marine and large trucks. I have also heard there is 'optiimum' fuelling for ideal EGT's and that 900-850 is the ver ymax that should be tolerated, ideally less than 900 degC Joe
|
|
|
Re: 20VT- BHP limit???
#43481
08/02/2006 19:55
08/02/2006 19:55
|
Anonymous
Unregistered
|
Anonymous
Unregistered
|
John, I've tried to make comparisons between aquamist on and off, but its hard as my aquamist is boost activated at 1bar or above, however I find I get higher EGT's running 0.9 bar with aquamist off, as compared to running 1.1bar with aquamist on? so I presume that the water injection does seem to make a difference.
regards
Joe
|
|
|
Re: 20VT- BHP limit???
#43485
08/02/2006 21:47
08/02/2006 21:47
|
Joined: Dec 2005
Posts: 991 Drakelow
Jamiepm
Club member 1989
|
Club member 1989
Enjoying the ride
Joined: Dec 2005
Posts: 991
Drakelow
|
I've seen as high as 910 at redline giving it some welly, but not sure if this is good bad or indifferent
Jamie
She's alive!
|
|
|
Re: 20VT- BHP limit???
#43486
09/02/2006 00:17
09/02/2006 00:17
|
Joined: Dec 2005
Posts: 286 Germany
Stichl
Making a profit
|
Making a profit
Joined: Dec 2005
Posts: 286
Germany
|
The highest EGT, we noticed at an original 20VT without any chiptuning, was 940°C (on a german autobahn at wot 260km/h for 5 minutes, ~ 25°C ambient temp.) Therefore I think, that 950°C are still ok!
Juergen
20VT coupegrale 4x4
|
|
|
Re: 20VT- BHP limit???
#43487
09/02/2006 00:39
09/02/2006 00:39
|
Joined: Dec 2005
Posts: 991 Drakelow
Jamiepm
Club member 1989
|
Club member 1989
Enjoying the ride
Joined: Dec 2005
Posts: 991
Drakelow
|
Ok, when I have my Unichip sorted I'll post up peak EGTs after that for comparison
Jamie
She's alive!
|
|
|
Re: 20VT- BHP limit???
#43488
09/02/2006 01:45
09/02/2006 01:45
|
Joined: Dec 2005
Posts: 3,158 Near Reading
JohnS
I need some sleep
|
I need some sleep
Joined: Dec 2005
Posts: 3,158
Near Reading
|
Quote:
If you cool the intake charge by 10 degree's (from a certain temp, say 25 degrees) then your exhaust temp will be 10 degrees less
That's true, but WI does actually reduce the EGTs by more than it reduces the charge temp because the water reduces the combustion temps and provides slightly cleaner combustion (which is why you can run more advance) On my car I've never seen more than 880C with WI on.
|
|
|
|