What Engine for 500BHP
Discussion
Is there an alternative to the GT30 that could be had for less money? Anything from BW or Precision? Or maybe someone could rebuild the current turbo with a GT30 compressor?
I have also heard that a bigger turbine wheel with a tighter AR can net both spool and power gains. Might be worth seeing if a tighter AR would help. Also what about the size of the headers / cross over? Is there any room to make either smaller to increase velocity?
I have also heard that a bigger turbine wheel with a tighter AR can net both spool and power gains. Might be worth seeing if a tighter AR would help. Also what about the size of the headers / cross over? Is there any room to make either smaller to increase velocity?
andygtt said:
What is the power curve like on a stock engine thats not turbocharged?
Despite the lower CR Id expect your power curve to be better than the NA everywhere and just have it increase when boost comes on.... if the stock engine doesn't have much power low down its going to be hard to change that dynamic pre turbo spool.
I will have to look for one, as I cant find it at present....Despite the lower CR Id expect your power curve to be better than the NA everywhere and just have it increase when boost comes on.... if the stock engine doesn't have much power low down its going to be hard to change that dynamic pre turbo spool.
stevieturbo said:
turbonutter said:
Stevie - the cams are not easily adjustable. The cam wheel/cam connection is a taper, with no key, so could be adjusted, but not something easily done, especially time wise on a RR.
Can you get vernier pulleys for them though ? to make it easily adjustable ?R8VXF said:
On the subject of the cam, all I really think I know is that for boosted applications you need little to no overlap between intake and exhaust valve opening to allow the turbo/supercharger to actually pressurise the cylinder, whereas NA you need the overlap to help keep the air flowing. I would look into seeing if you can get a CAM designed for boost IMO, will improve the engine a lot.
It really depends. If the system does see much higher pressure in the exhaust manifold, then yes. You dont really want any overlap for obvious reasons. But as it also depends how well heads etc flow, rpm's etc etc there is no easy answer.Well there is, cams with little or no overlap will always be safe and capable of great drive ability and good power. The worst thing you'll ever do on a turbo engine is go too big with the cams. Usually that just hurts low end drive ability, spool, torque.....all for very little if any real gain up top, and can just shift the power band upwards, often without actually making you go any faster.
the more efficient you can make the build, the closer to 1:1 EGBP vs Manifold pressure...the more you can push with the cams without worry of it turning the car into a piece of s
t to drive.His cams are fine though, it isnt an all out race engine, but it would be nice to be able to play with the timing a bit if it could be done easily.
Maybe advance the exhaust cam a bit to try, might make it spool a little earlier.
But the GT30 sounds like a good plan.
Think I will keep mye eye out for a GT3076...
chuntington101 said:
Is there an alternative to the GT30 that could be had for less money? Anything from BW or Precision? Or maybe someone could rebuild the current turbo with a GT30 compressor?
I have also heard that a bigger turbine wheel with a tighter AR can net both spool and power gains. Might be worth seeing if a tighter AR would help. Also what about the size of the headers / cross over? Is there any room to make either smaller to increase velocity?
I want to stick to the GT range as, if I use the tial housing, it will be a direct swap....I have also heard that a bigger turbine wheel with a tighter AR can net both spool and power gains. Might be worth seeing if a tighter AR would help. Also what about the size of the headers / cross over? Is there any room to make either smaller to increase velocity?
Seen one for sale at the moment, but it has the 0.82 tial housing.. I think the 1.02 would be better as its closer to what I have with the 0.82 on my gt35
turbonutter said:
I want to stick to the GT range as, if I use the tial housing, it will be a direct swap....
Seen one for sale at the moment, but it has the 0.82 tial housing.. I think the 1.02 would be better as its closer to what I have with the 0.82 on my gt35
If it comes with that housing, I'd just try it like that anyway. No sense spending extra money without trying it.Seen one for sale at the moment, but it has the 0.82 tial housing.. I think the 1.02 would be better as its closer to what I have with the 0.82 on my gt35
I guess the cam verniers not such a good idea lol.
There arent so many sellers of the likes of BW etc, and by time you by abroad with all duties etc, prob not much in it. The Garrett's are all over the place so not overly expensive.
Only big downside with them, if there is a problem they're effectively scrap as they cannot be rebuilt.
Whilst it'd probably be too small, and it's on a regular T3 flanges etc, I've a new Turbonetics GTK-550 here that was never used. Probably wouldnt cost a fortune.
Not sure if it's interchangeable with the Tial T3 housings or not.
A friend bought it years ago and never used it.
stevieturbo said:
If it comes with that housing, I'd just try it like that anyway. No sense spending extra money without trying it.
I guess the cam verniers not such a good idea lol.
There arent so many sellers of the likes of BW etc, and by time you by abroad with all duties etc, prob not much in it. The Garrett's are all over the place so not overly expensive.
Only big downside with them, if there is a problem they're effectively scrap as they cannot be rebuilt.
Whilst it'd probably be too small, and it's on a regular T3 flanges etc, I've a new Turbonetics GTK-550 here that was never used. Probably wouldnt cost a fortune.
Not sure if it's interchangeable with the Tial T3 housings or not.
A friend bought it years ago and never used it.
I was thinking along the same lines - try the 3076 with the 0.82a/r if it needed a bigger housing, I wouldnt have lost anything!I guess the cam verniers not such a good idea lol.
There arent so many sellers of the likes of BW etc, and by time you by abroad with all duties etc, prob not much in it. The Garrett's are all over the place so not overly expensive.
Only big downside with them, if there is a problem they're effectively scrap as they cannot be rebuilt.
Whilst it'd probably be too small, and it's on a regular T3 flanges etc, I've a new Turbonetics GTK-550 here that was never used. Probably wouldnt cost a fortune.
Not sure if it's interchangeable with the Tial T3 housings or not.
A friend bought it years ago and never used it.
No vernier pulleys not so great....
I would have to look into the gtk550, but doubt it would fit the tial housing ....
https://www.youtube.com/watch?v=3fnbcSQSocY
Still running factory cam's?
She sounds a little flat.
Have a word with these chaps...
https://www.facebook.com/NJS-Fiat-Alfa-Romeo-Abart...
...they're building another full race 3.2 the profiles could be beneficial. If the exhaust timing on the cam's is holding your turbo back.
Still running factory cam's?
She sounds a little flat.
Have a word with these chaps...
https://www.facebook.com/NJS-Fiat-Alfa-Romeo-Abart...
...they're building another full race 3.2 the profiles could be beneficial. If the exhaust timing on the cam's is holding your turbo back.
turbonutter said:
Evoluzione said:
We've got some Dyno simulation software at work, I can do some sims on this if you're interested and can get me some precise specs.
What specs would you need?Cam specs? I'll enter those you supplied, but am dubious unless you have any provenance and that they can be trusted? With older Fiat group stuff (before yours) they quoted cam specs in a strange way which could throw the unwary. I don't know whether they did this on purpose or not, although if I put them in and we hit a match I guess they will be correct.
Bore
stroke
Rod length
Pin offset
Static CR
Valve diameters and min port CSA of in & ex
Port flow at a range of valve lifts
Direct acting or rockers?
Intake runner length from valve to entry in plenum
Runner entry area
Port min CSA
Throttle blade size
Turbo name and spec
Ex manifold int' dia'
Tube length
Collector length, entry area and exit area.
Do you have your latest power figures in a table format rather than graph?
Do you have the power figures for an original untouched N/A engine? The more explicit the better.
Once all that is programmed in and I can cross reference it with a known quantity then it gets easier, all I need to do is put in your suggestions for change (cams & turbo) and we see an instant result - certainly better than guessing!
I think swapping the turbo out is a waste of time, the '35 is a good unit and with 3.2 litres of heat energy pumping through it should spool up quick. Going to a GT30 is a backward step, it's your cams that are holding it up in particular the exhaust, but I can see the cost of four cams and verniers putting you off.
Look at it this way, how can an ex cam designed to handle 250bhp possibly be any good for double that power?
I've seen GT35s spool quicker/earlier on only 2ltrs.
Evoluzione said:
Look at it this way, how can an ex cam designed to handle 250bhp possibly be any good for double that power?
I've seen GT35s spool quicker/earlier on only 2ltrs.
I've run engines with std cams pushing 3-4x what they would normally have put out. And bare in mind some turbo engines use even milder profiles than their n/a counterparts.I've seen GT35s spool quicker/earlier on only 2ltrs.
You do not need massive duration or lift to achieve great performance with a turbo setup, and as said, it's very easy to use too much cam.
Evoluzione said:
I'll list them. Port flows we are going to struggle with I assume?
Bore
stroke
Rod length
Pin offset
Static CR
Valve diameters and min port CSA of in & ex
Port flow at a range of valve lifts
Direct acting or rockers?
Intake runner length from valve to entry in plenum
Runner entry area
Port min CSA
Throttle blade size
Turbo name and spec
Ex manifold int' dia'
Tube length
Collector length, entry area and exit area.
Do you have your latest power figures in a table format rather than graph?
Do you have the power figures for an original untouched N/A engine? The more explicit the better.
Most of that I can get, but it will take a while... Port flows as you suspect I dont have, also min pors CSA will be difficult.Bore
stroke
Rod length
Pin offset
Static CR
Valve diameters and min port CSA of in & ex
Port flow at a range of valve lifts
Direct acting or rockers?
Intake runner length from valve to entry in plenum
Runner entry area
Port min CSA
Throttle blade size
Turbo name and spec
Ex manifold int' dia'
Tube length
Collector length, entry area and exit area.
Do you have your latest power figures in a table format rather than graph?
Do you have the power figures for an original untouched N/A engine? The more explicit the better.
The only thing I am not sure on what you mean is "PIN OFFSET"
also do you want just the power figures or torque as well
Edited by turbonutter on Saturday 31st October 22:26
Both if you can, the more accurate info I have, the more accurate info I can give you - garbage in, garbage out as they say in the US. Although if I guesstimate and we match the known OE figures as a baseline we're off to a good start and I can build the fuller picture from there.
Piston pin offset is likely 1mm, although in 500bhp will only give 1bhp difference from 0!
Piston pin offset is likely 1mm, although in 500bhp will only give 1bhp difference from 0!
Evoluzione said:
garbage in, garbage out as they say in the US.
That's the problem with all sims or calcs. DynoSim is a nice idea....but not sure they'd be as reliable as you'd like given so many variables.For mere mortals like is, getting correct and accurate data data will be nigh on impossible for anything that cant physically be measured easily.
GIGO is quite a universal saying....some people will go around quoting all the maths they can dream up to give them the answers they want to see, without understanding if the base they're working from is wrong...they'll never get correct answers !
But they'll seem correct because they're telling them what they wanted to see.
For this, it'd be easier just to try the GT30 lol, but I still cant understand why the GT35 is so laggy. It doesnt make a lot of sense, but as Andy suggested, maybe these engines just dont make much below 4500rpm anyway ?
I wonder would throwing either cam out a tooth be worth a try ? I guess even with some "wrong" data, the Dyno Sim software might shed some light as to how that might affect things ? Can it offer suggestions on how it might affect turbo spool ?
ie open exhaust cam earlier to try and force some spool ?
Before you spend ages messing around, get a psuedo steady state curve!
Ie, 4th gear, against the brakes on a long straight empty road (or chassis dyno), from 1000rpm upwards. Got WOT, use the brakes to drag you down to 1000rpm, slowly let the rpm increase. If you can do it uphill it helps too. You only need to go to the revs where boost is fully built, so probably 3.5krpm ish. This steady state curve can then be compared to the dynamic curve and you'll see if it's a turbo inertia issue or a sizing one.
You can also play around with the ignition angle at low rpms, trade off some off-boost torque for more turbine energy to get it started earlier. Remember, turbo's are positive feedback devices. More boost = more air = more fuel = more exhaust energy = more boost etc etc. Small changes in exhaust energy at say 2000rpm can massively affect the fully spooled point!
Ie, 4th gear, against the brakes on a long straight empty road (or chassis dyno), from 1000rpm upwards. Got WOT, use the brakes to drag you down to 1000rpm, slowly let the rpm increase. If you can do it uphill it helps too. You only need to go to the revs where boost is fully built, so probably 3.5krpm ish. This steady state curve can then be compared to the dynamic curve and you'll see if it's a turbo inertia issue or a sizing one.
You can also play around with the ignition angle at low rpms, trade off some off-boost torque for more turbine energy to get it started earlier. Remember, turbo's are positive feedback devices. More boost = more air = more fuel = more exhaust energy = more boost etc etc. Small changes in exhaust energy at say 2000rpm can massively affect the fully spooled point!
Evoluzione said:
Max_Torque said:
Stuff
Would you happen to know if there are any trends in de-catting a turbo car? What I mean is, would it generally do xx to the BHP and xx to the Tq figure?Evoluzione said:
Look at it this way, how can an ex cam designed to handle 250bhp possibly be any good for double that power?
That doesn't actually make much sense. Turbocharging increases the inlet manifold air density and consequently the cylinder pressure in proportion. Exhaust port flow rate also then increases due to the higher cylinder pressure. It doesn't require any more exhaust cam duration to cope with that than the same engine normally aspirated because everything scales in proportion.Various scribblings on turbo engines.
https://web.archive.org/web/20110918115242/http://...
https://web.archive.org/web/20110903073220/http://...
Max_Torque said:
Before you spend ages messing around, get a psuedo steady state curve!
Ie, 4th gear, against the brakes on a long straight empty road (or chassis dyno), from 1000rpm upwards. Got WOT, use the brakes to drag you down to 1000rpm, slowly let the rpm increase. If you can do it uphill it helps too. You only need to go to the revs where boost is fully built, so probably 3.5krpm ish. This steady state curve can then be compared to the dynamic curve and you'll see if it's a turbo inertia issue or a sizing one.
You can also play around with the ignition angle at low rpms, trade off some off-boost torque for more turbine energy to get it started earlier. Remember, turbo's are positive feedback devices. More boost = more air = more fuel = more exhaust energy = more boost etc etc. Small changes in exhaust energy at say 2000rpm can massively affect the fully spooled point!
That sounds like a reasonable test to make, will try to get it done this week... Ie, 4th gear, against the brakes on a long straight empty road (or chassis dyno), from 1000rpm upwards. Got WOT, use the brakes to drag you down to 1000rpm, slowly let the rpm increase. If you can do it uphill it helps too. You only need to go to the revs where boost is fully built, so probably 3.5krpm ish. This steady state curve can then be compared to the dynamic curve and you'll see if it's a turbo inertia issue or a sizing one.
You can also play around with the ignition angle at low rpms, trade off some off-boost torque for more turbine energy to get it started earlier. Remember, turbo's are positive feedback devices. More boost = more air = more fuel = more exhaust energy = more boost etc etc. Small changes in exhaust energy at say 2000rpm can massively affect the fully spooled point!
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