N/A or Low Pressure Turbo?
Discussion
Just a quick one; I wondering have many people on here got experience of low pressure Turbos?
I'm in the midst of a chassis refurb, and despite my initial hesitation in spending even more money on the engine, I'm fighting the temptation to go ahead with my GEMS conversion, part of this being at 'least' a bottom end build. Although initially being adamant I was sticking with NA and using conventional tuning, I can't help wonder about a low pressure turbo??? I prefer the idea of a SC, just not the price, so just wondering power aside, what people's experiences? Does the low pressure turbo run out of steam too quick and so limit the engines revabillty?....better sticking NA to keep the character of the car???
I'm in the midst of a chassis refurb, and despite my initial hesitation in spending even more money on the engine, I'm fighting the temptation to go ahead with my GEMS conversion, part of this being at 'least' a bottom end build. Although initially being adamant I was sticking with NA and using conventional tuning, I can't help wonder about a low pressure turbo??? I prefer the idea of a SC, just not the price, so just wondering power aside, what people's experiences? Does the low pressure turbo run out of steam too quick and so limit the engines revabillty?....better sticking NA to keep the character of the car???
My two year old Audi is turbo charged, it's enough to put you off turbos for life!
A huge amount of the pleasure I get from driving my TVR comes from the analogue direct connection between foot and throttle butterfly, it's cause and effect, every millimeter of throttle pedal movement up or down should have an equal and opposite effect on engine speed and forward motion.
This, an engine that revs and one that continues to pile on the power exponentially with engine speed is where true pleasure lives
There's no doubt big numbers are easy with a turbo, but to measure success on a peak figure alone is like claiming a meal is better because you got more on your plate, if you're a real connoisseur it's the taste and dinning experience that really counts
My very modern Audi makes huge torque for it's given engine capacity, but it happens in such a narrow power band you really start to question if all this turbo business really is progress
Stab the throttle quickly to capitalise on a gap as you roll up to a roundabout and nothing happens for what seems like an eternity...........
, ............................literally nothing, like the throttle pedal has become disconnected!
Then, just when you think the car is definitely broken, you've completely lost that gap......... and your brain starts to switch to "Oh Ship, that car on the right might hit me".................. just as you start to calculate how the hell you're going to get yourself out of this very scary situation............... and an absolute age since you stabbed the throttle to ask for power................ you suddenly find yourself in a world of violent Boooooost!!!! and you shoot off like a scolded cat
You'd think they would have worked this turbo business out by now, there's absolutely no excuses in this day and age for a respected car maker like Audi to still be offering a car with such truly appalling power delivery
A huge amount of the pleasure I get from driving my TVR comes from the analogue direct connection between foot and throttle butterfly, it's cause and effect, every millimeter of throttle pedal movement up or down should have an equal and opposite effect on engine speed and forward motion.
This, an engine that revs and one that continues to pile on the power exponentially with engine speed is where true pleasure lives
There's no doubt big numbers are easy with a turbo, but to measure success on a peak figure alone is like claiming a meal is better because you got more on your plate, if you're a real connoisseur it's the taste and dinning experience that really counts
My very modern Audi makes huge torque for it's given engine capacity, but it happens in such a narrow power band you really start to question if all this turbo business really is progress
Stab the throttle quickly to capitalise on a gap as you roll up to a roundabout and nothing happens for what seems like an eternity...........
, ............................literally nothing, like the throttle pedal has become disconnected!Then, just when you think the car is definitely broken, you've completely lost that gap......... and your brain starts to switch to "Oh Ship, that car on the right might hit me".................. just as you start to calculate how the hell you're going to get yourself out of this very scary situation............... and an absolute age since you stabbed the throttle to ask for power................ you suddenly find yourself in a world of violent Boooooost!!!! and you shoot off like a scolded cat
You'd think they would have worked this turbo business out by now, there's absolutely no excuses in this day and age for a respected car maker like Audi to still be offering a car with such truly appalling power delivery
^ Are those audi's diesels? I've always had older saab's and they're really quite sharp to drive especially on interesting roads :-) They have their own soundtract to and 9:1 c/r so there isn't any lag to worry about. Plant your foot and drive.
A friend has a v6 corrado and that sounds wonderful, you even feel that you're going fast :-)
A friend has a v6 corrado and that sounds wonderful, you even feel that you're going fast :-)
Depends on your budget and long term aims. I went through the thoughts of boosting but worked out id have needed in the region of about £6500 to do it properly, which at the time I could not justify.
In the end i decided to just do a minor bottom end refurb and some nice goodies for the top end, problem is I reckon ive spent about £4000 including tools etc doing this so you have to think carefully.
In the end i decided to just do a minor bottom end refurb and some nice goodies for the top end, problem is I reckon ive spent about £4000 including tools etc doing this so you have to think carefully.
I mainly run mine at 2.5 psi on the road, so really low turbo pressure.
Gives me 325 bhp from a bog standard RR 4.6 engine.
Feels just like my old 5 litre V8D NA engine felt (that had 315 bhp).
When I turn the wick up to 7.5 psi I get around 380-390 bhp and over 500 ft lbs. Torque band is narrower, but higher if you see what i mean.
Still feels the same - just like my Saab Aero (see Boosted LS1's comment - I have one too), the low compression ratio seems to eliminate turbo lag on the TVR.
If you are coming anywhere near Burghley (TVRCC car show) in a couple of weeks time you are welcome to drive my car and see what you think, OP.
Gives me 325 bhp from a bog standard RR 4.6 engine.
Feels just like my old 5 litre V8D NA engine felt (that had 315 bhp).
When I turn the wick up to 7.5 psi I get around 380-390 bhp and over 500 ft lbs. Torque band is narrower, but higher if you see what i mean.
Still feels the same - just like my Saab Aero (see Boosted LS1's comment - I have one too), the low compression ratio seems to eliminate turbo lag on the TVR.
If you are coming anywhere near Burghley (TVRCC car show) in a couple of weeks time you are welcome to drive my car and see what you think, OP.
PS, someone mentioned temperatures under bonnet. I don't have any turbo heat issues in road use, or cooler track days, but have noticed some heat issues on a track day on a hot day.
We are working on solutions at the moment - current favourite is a quick-release cooling fan, that I can remove for track days - at track speed the issue is that the fans actually get in the way of the airflow through the radiator.
Also the siting of the intercooler bang in front of the radiator may not be helping.
We are working on solutions at the moment - current favourite is a quick-release cooling fan, that I can remove for track days - at track speed the issue is that the fans actually get in the way of the airflow through the radiator.
Also the siting of the intercooler bang in front of the radiator may not be helping.
Classic Chim said:
Charactor wins over every time. N/A
Because power isn’t everything.
Charm and sound are just as important and I just prefer the sound of n/a.
Dude, such a shame you never got to have a go in my car with a clear stretch of road. (no comparison to diesel lag) Especially with adjustable boost on steering wheel. (4, 12 or 19 psi) Turbo is the future and the turbo cars of the eighties are far long gone but people still keep quoting the same 'Clarkson says so must be true' shyte. (why are big manufacturers not going SC?) Proper sized, proper build, proper management = EPIC.Because power isn’t everything.
Charm and sound are just as important and I just prefer the sound of n/a.
However, I do have a like for N/A too, but ultimately it's about, what you want and wallet size. A standard 450 for example is a perfect start point for bolting on a turbo having low compression (it's actually nearer 8.9:1 than 9.35:1 as stamped on the block because of composite gaskets and valve cut outs) it has big valve heads (28cc not 36cc) and every bit helps with FI just as with N/A. Just keep boost levels sensible and all should be well. Up capacity N/A or drop CR on turbo will hurt fuel consumption (Daz beware :hehe ) there's always a trade off.
Bugger, just realised I'm not talking to Al' as you were.
turbo's rock
Oh, s
t I am! Shouldn't you be practicing dude? Only one more sleep 
Edited by macdeb on Sunday 25th March 17:48
Edited by macdeb on Sunday 25th March 17:49
Edited by macdeb on Sunday 25th March 17:50
Oh Lord.. ....this question was a mistake to ask....I'll never decide now and end up making the THE WRONG decision! Lol 
I was planning on getting the bottom end rebuild/top hat/balance and gems cam.....then decided to hold fire due to financials.. ..now in saying f@#k it and life too short not to.....so guessing it will be off to V8D shortly.
I won't know 100% what heads/valves I've got until their off, but had planned to get them flowed with the manifolds at some stage, hopefully bottom end rebuild time, so was just trying to 100% decide on a direction so as I either keep compression or up it, what can to fit, 72mm plenum or not. I don't want a power house of a thing, just a reallly nice balanced and reliable motor.....with character of course!
I was planning on getting the bottom end rebuild/top hat/balance and gems cam.....then decided to hold fire due to financials.. ..now in saying f@#k it and life too short not to.....so guessing it will be off to V8D shortly.
I won't know 100% what heads/valves I've got until their off, but had planned to get them flowed with the manifolds at some stage, hopefully bottom end rebuild time, so was just trying to 100% decide on a direction so as I either keep compression or up it, what can to fit, 72mm plenum or not. I don't want a power house of a thing, just a reallly nice balanced and reliable motor.....with character of course!
macdeb said:
Classic Chim said:
Charactor wins over every time. N/A
Because power isn’t everything.
Charm and sound are just as important and I just prefer the sound of n/a.
Dude, such a shame you never got to have a go in my car with a clear stretch of road. (no comparison to diesel lag) Especially with adjustable boost on steering wheel. (4, 12 or 19 psi) Turbo is the future and the turbo cars of the eighties are far long gone but people still keep quoting the same 'Clarkson says so must be true' shyte. (why are big manufacturers not going SC?) Proper sized, proper build, proper management = EPIC.Because power isn’t everything.
Charm and sound are just as important and I just prefer the sound of n/a.
However, I do have a like for N/A too, but ultimately it's about, what you want and wallet size. A standard 450 for example is a perfect start point for bolting on a turbo having low compression (it's actually nearer 8.9:1 than 9.35:1 as stamped on the block because of composite gaskets and valve cut outs) it has big valve heads (28cc not 36cc) and every bit helps with FI just as with N/A. Just keep boost levels sensible and all should be well. Up capacity N/A or drop CR on turbo will hurt fuel consumption (Daz beware :hehe ) there's always a trade off.
Bugger, just realised I'm not talking to Al' as you were.
turbo's rock
Oh, s
t I am! Shouldn't you be practicing dude? Only one more sleep Edited by macdeb on Sunday 25th March 17:48
Edited by macdeb on Sunday 25th March 17:49
Edited by macdeb on Sunday 25th March 17:50
For me it’s not about the numbers produced but the rush when boost comes in.
A standard 4.0 or 4.6 V8 at 1500- 2000 rpm is the same as a turbo charged one so lag is not really an issue like a 4 cylinder diesel. The difference comes after 2500rpm all the way to 6000. Similar to a big cam.
During normal road use I suspect there is very little additional heat produced as the previous heat producing cat has been removed and replaced by the turbo.
Power to pound it has been the best investment I have made. I still run a standard computer and distributor on an engine that’s done 125000 miles. It’s a 4.0 running 5 psi it makes 330hp and 350ft/lb. I was lucky enough to purchase a Powers kit that had not been installed. All in it cost around £2000 plus a Joolz remap.
Lots of room for improvement in the future with computer, and distributor, lightened flywheel, new engine when the old one lets go.
The noise is similar to standard but I do miss the Clive F no cat exhaust sound. I hope to improve this next.
Qbee/ Macdeb did you make improvements to your exhaust and sound?
To answer the exhaust question first, my car is now quieter - I was fully decatted already, and the turbo acts as a muffler in the system. I used to struggle to make track day noise limits (101-105 dB). My car is now around 95dB. I have been there, done that with noise, now enjoying a less tiring car to drive distances. So is my deaf wife.
Motul, we should meet up before you commit. I am not in any way trying to influence you, but if you are possibly turbocharging, you want the opposite kind of engine to the V8D offering. You can drive my car and see what you think of the turbo at 325, 375 and 395 bhp
So long as you aren’t going for MacDeb’s 500+ bhp, in which case you will need a totally different engine, drive train, clutch, gearbox etc or break it, in order to get around 400 bhp NA will require a 5.5 engine, double or triple plenum etc, all at as high as possible compression etc. Expensive.
If you are going turbo to 400 bhp, you want to build a low compression engine, minimal valve overlap, standard cam, basically the engine you get out of a 4.6 P38 Range Rover.
Send me an email, I am sure we can meet up somewhere convenient. I am at Newark on Trent. Happy to toddle over to Buxton or Macclefield and do some Peak District exploring if you are.
Motul, we should meet up before you commit. I am not in any way trying to influence you, but if you are possibly turbocharging, you want the opposite kind of engine to the V8D offering. You can drive my car and see what you think of the turbo at 325, 375 and 395 bhp
So long as you aren’t going for MacDeb’s 500+ bhp, in which case you will need a totally different engine, drive train, clutch, gearbox etc or break it, in order to get around 400 bhp NA will require a 5.5 engine, double or triple plenum etc, all at as high as possible compression etc. Expensive.
If you are going turbo to 400 bhp, you want to build a low compression engine, minimal valve overlap, standard cam, basically the engine you get out of a 4.6 P38 Range Rover.
Send me an email, I am sure we can meet up somewhere convenient. I am at Newark on Trent. Happy to toddle over to Buxton or Macclefield and do some Peak District exploring if you are.
Edited by QBee on Sunday 25th March 19:12
exhaust sound? I experimented extensively with different arrangements. To cut a long story short I settled on two 10" cherry bombs in place of mid box. Don't like it to sound agricultural nor too loud so nice balance between the two. Easy to do and cheap enough also.
On mod-build front,,, standard 450, sensible boost, happy days. Speak to Eann Whalley (torque rv8). Once on the road for power, it can be a very slippery slope and damage the wallet extensively. Good luck and keep us posted.
On mod-build front,,, standard 450, sensible boost, happy days. Speak to Eann Whalley (torque rv8). Once on the road for power, it can be a very slippery slope and damage the wallet extensively. Good luck and keep us posted.
motul1974 said:
Oh Lord.. ....this question was a mistake to ask....I'll never decide now and end up making the THE WRONG decision! Lol
I was planning on getting the bottom end rebuild/top hat/balance and gems cam.....then decided to hold fire due to financials.. ..now in saying f@#k it and life too short not to.....so guessing it will be off to V8D shortly.
I won't know 100% what heads/valves I've got until their off, but had planned to get them flowed with the manifolds at some stage, hopefully bottom end rebuild time, so was just trying to 100% decide on a direction so as I either keep compression or up it, what can to fit, 72mm plenum or not. I don't want a power house of a thing, just a reallly nice balanced and reliable motor.....with character of course!
Any stock build that's not over 9:1 will allow 7 lbs of boost. That's a lot of extra air pumping into your cylinders. A Rover n/a engine can never fill it's cylinders. You don't need to spend any more on a turbo engine build then you would on a n/a build. So, when you spec the engine you can always keep the turbo option open. :-)I was planning on getting the bottom end rebuild/top hat/balance and gems cam.....then decided to hold fire due to financials.. ..now in saying f@#k it and life too short not to.....so guessing it will be off to V8D shortly.
I won't know 100% what heads/valves I've got until their off, but had planned to get them flowed with the manifolds at some stage, hopefully bottom end rebuild time, so was just trying to 100% decide on a direction so as I either keep compression or up it, what can to fit, 72mm plenum or not. I don't want a power house of a thing, just a reallly nice balanced and reliable motor.....with character of course!
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