1.8T - wot no torque ?

[RobT]

Hi

I have been scanning through a few car specs recently and got to wondering why the 1.8T, even when pretty well modified, is relatively not that torquey

eg. 2L cossie turbos frequently put out over 400ftlb when modded...seems the 1.8T struggles to top the 300 mark....

Just wondered why.. ? obviously 200cc difference but still seems a bit down on the old cossie lump

Rob

[m0rk]

Not that I know, but does the bore & stroke have much to do with it?

eg would a large bore & short stroke provide more torque?

[Big Fish]

torque seems to be kept within safety limits by most tuners normally for gearbox and clutch and diff etc reasons.

am sure if you speak to quaiffe (sp) they can up the power handling capacity on all such helpful ancillaries to cope with more torque

BF

[Nippa]

Originally posted by m0rk
Not that I know, but does the bore & stroke have much to do with it?

eg would a large bore & short stroke provide more torque?

Actually, it's more like the other way around.. Short stroke = less torque, but can rev higher. Hence why fast motorbikes dont have much torque (Dont need it cos they weigh bugger all) But can rev like crazy right around the clock, while still having an impressively high bhp output relative to the cc of the engine.

Not sure why cossie lumps fair better than 1.8T's in the torque department though. But naturally the 200cc capacity difference will account for a significant proportion of that difference in torque output. Also, the 1.8T is already a relatively long stroke motor. So torque should be good (and relatively speaking, it IS good). I am not familiar with 2.0 cossie lumps, but it's possible they have an even longer stroke? Other than that.. Could be any number of things.. Including the bloody great big old skool peaky output turbo's people like to bolt onto cossie engines.
But hey, 300bls of torque is plenty when you consider many cars that the 1.8T engine is used in, most likely weigh an awful lot less than a Sierra or Escort cosworth.

[BenS1]

Generally with the 1.8T i have noticed that you get roughly the same bhp as torque, eg. 200bhp 207lb/ft torque on a chip, 320bhp 290lb/ft on an IHI upgrade, 450bhp 420lb/ft on a Stage 5 upgrade etc.

So, you can have as much torque as you want given a big enough turbo.

Do Cossies with 400lb/ft of torque have over 400bhp? If so then thats comparable with an 1.8T stage 5 upgrade. If not then that implies that the torque falls off rather rapidly as the revs rise. As bhp = torque * rpm if torque remained high at high revs them bhp would be very high too. This probably implies the turbo is getting breathless in much the same way the little K03 does as the revs rise.

Note bhp = torque * rpm/ 5252 if using bhp and lb/ft.

Cheers
Ben

[Dormouse]

Didn't the tuned Cosworths use feck-off big Garrett Turbos? Hence the massive Torque?

Dor.

[Shock_Xe]

cossies have T25/T3 as standard and both are which are massive compared to the ickle K03

[CupraR-Rog]

Originally posted by Shock_Xe
cossies have T25/T3 as standard and both are which are massive compared to the ickle K03
Big Turbo, Lotsa Turbo Lag!!

I guess that where the K03 / K03s / K04 come into their own is in the wide spread of torque - the cossies might only have a spike, compared to the flat-line response of the 1.8T...

[Dormouse]

The plot and response are differnet things.

The Garrett will infact have a huge torque across it's range. However it's the time it takes to spin up which its the down side.

Dor.

[max_torque]

The cosworth YB series engines have a high specific torque output because of 1 major reason, they were designed at a "high charge motion" turbo engine, whilst the 1.8t also is requried to make reasonable performance as an normally asporated engine. Hence the Cosworths intake geometery is biased towards generating motion within the incoming cylinder charge, at the expense of reducing the maximum flow capacity of the intake port. In combination with the high squish combustion chamber design this results in a very rapid burn rate of the charge when compared to the 1.8t engine. (1.8t burns at a maximum pressure rise per degree of crank rotation of approximately 3 bar per degree, YB series burn at 6 bar/ degree.

This is very important at low to medium speeds, where a slow burning chamber the pressure and temperature rise slowly (relatively speaking obviously!) and typically this will lead to the onset of detonation in the extremities of the chamber, before the whole charge has burnt, hence you are limited in the ignition advance you can run and hence the torque ouput for a given boost level. On the YB it burns so fast that the temp and pressure rise very quickly, but all the charge has burnt so there's nothing for DET to "explode". As engine speed increases the time for combustion decreases and this becomes of less importance.

The downside of a high charge motion port is the reduction in airflow, but with a turbo you just turn the boost up a bit, but the 1.8t needs a decent-ish port flow for the NA version so it's more of a comprimise.

A long stroke engine will give more torque than a short stoke engine of the same capacity as there will be more "leverage" on the crank, but the shouded small valves and higher pistons speeds asociated with this long stroke will limit maximum power output.

[Dormouse]

You got that out of a cracker didn't you! :p

Dor.

[Shock_Xe]

Originally posted by max_torque
The cosworth YB series engines have a high specific torque output because of 1 major reason, they were designed at a "high charge motion" turbo engine, whilst the 1.8t also is requried to make reasonable performance as an normally asporated engine. Hence the Cosworths intake geometery is biased towards generating motion within the incoming cylinder charge, at the expense of reducing the maximum flow capacity of the intake port. In combination with the high squish combustion chamber design this results in a very rapid burn rate of the charge when compared to the 1.8t engine. (1.8t burns at a maximum pressure rise per degree of crank rotation of approximately 3 bar per degree, YB series burn at 6 bar/ degree.

This is very important at low to medium speeds, where a slow burning chamber the pressure and temperature rise slowly (relatively speaking obviously!) and typically this will lead to the onset of detonation in the extremities of the chamber, before the whole charge has burnt, hence you are limited in the ignition advance you can run and hence the torque ouput for a given boost level. On the YB it burns so fast that the temp and pressure rise very quickly, but all the charge has burnt so there's nothing for DET to "explode". As engine speed increases the time for combustion decreases and this becomes of less importance.

The downside of a high charge motion port is the reduction in airflow, but with a turbo you just turn the boost up a bit, but the 1.8t needs a decent-ish port flow for the NA version so it's more of a comprimise.

A long stroke engine will give more torque than a short stoke engine of the same capacity as there will be more "leverage" on the crank, but the shouded small valves and higher pistons speeds asociated with this long stroke will limit maximum power output.

Well Obviously

[WileEcoyote]

Originally posted by max_torque
The cosworth YB series engines have a high specific torque output because of 1 major reason, they were designed at a "high charge motion" turbo engine, whilst the 1.8t also is requried to make reasonable performance as an normally asporated engine. Hence the Cosworths intake geometery is biased towards generating motion within the incoming cylinder charge, at the expense of reducing the maximum flow capacity of the intake port. In combination with the high squish combustion chamber design this results in a very rapid burn rate of the charge when compared to the 1.8t engine. (1.8t burns at a maximum pressure rise per degree of crank rotation of approximately 3 bar per degree, YB series burn at 6 bar/ degree.

This is very important at low to medium speeds, where a slow burning chamber the pressure and temperature rise slowly (relatively speaking obviously!) and typically this will lead to the onset of detonation in the extremities of the chamber, before the whole charge has burnt, hence you are limited in the ignition advance you can run and hence the torque ouput for a given boost level. On the YB it burns so fast that the temp and pressure rise very quickly, but all the charge has burnt so there's nothing for DET to "explode". As engine speed increases the time for combustion decreases and this becomes of less importance.

The downside of a high charge motion port is the reduction in airflow, but with a turbo you just turn the boost up a bit, but the 1.8t needs a decent-ish port flow for the NA version so it's more of a comprimise.

A long stroke engine will give more torque than a short stoke engine of the same capacity as there will be more "leverage" on the crank, but the shouded small valves and higher pistons speeds asociated with this long stroke will limit maximum power output.



That's what i was going to say!:D

[CupraR-Rog]

Originally posted by max_torque
The cosworth YB series engines have a high specific torque output because of 1 major reason, they were designed at a "high charge motion" turbo engine, whilst the 1.8t also is requried to make reasonable performance as an normally asporated engine. Hence the Cosworths intake geometery is biased towards generating motion within the incoming cylinder charge, at the expense of reducing the maximum flow capacity of the intake port. In combination with the high squish combustion chamber design this results in a very rapid burn rate of the charge when compared to the 1.8t engine. (1.8t burns at a maximum pressure rise per degree of crank rotation of approximately 3 bar per degree, YB series burn at 6 bar/ degree.

This is very important at low to medium speeds, where a slow burning chamber the pressure and temperature rise slowly (relatively speaking obviously!) and typically this will lead to the onset of detonation in the extremities of the chamber, before the whole charge has burnt, hence you are limited in the ignition advance you can run and hence the torque ouput for a given boost level. On the YB it burns so fast that the temp and pressure rise very quickly, but all the charge has burnt so there's nothing for DET to "explode". As engine speed increases the time for combustion decreases and this becomes of less importance.

The downside of a high charge motion port is the reduction in airflow, but with a turbo you just turn the boost up a bit, but the 1.8t needs a decent-ish port flow for the NA version so it's more of a comprimise.

A long stroke engine will give more torque than a short stoke engine of the same capacity as there will be more "leverage" on the crank, but the shouded small valves and higher pistons speeds asociated with this long stroke will limit maximum power output.
All I know, is the information : champaign ratio's a little uneven here...

Makes perfect sense when you put it that way!! (( :confused: ))

[RobT]

Thanks - I thought there had to be some fundamental reason for it as the figures just didn't add up

Confimed...1.8T is not that great a turbo motor - BY DESIGN !

By the way - I was reading a mag over xmas that was on about most power per cc in a NA engine - 320bhp/l honda got 14yrs ago with a TT motorbike engine at 21.5K rpm !

Anyone beat this ? - todays F1 engines are approx. 900bhp / 3L = 300 bhp/l - dont seem that hreat when you consider what honda did 14 yrs ago

Ave it

Dave

[Ibiza sport man]

If I remember correctly Honda got that power from a 5 cylinder 125 cc engine in the late 60's. So 35 years ago !!

So much for progress.