156 rev range 23,000-28,000

[Jonsiv]

Good afternoon all,

Being new to this forum and a new owner of a 1998 alfa 156 2.0 this has to be the place to come for advise.

I have seen alot of people just want to help one another out.

I bet somewhere in the 711 pasges of post this has come up before but here goes.

Why is it that in the rev range of 23,000-28,000 the Alfa appears to lose power and once it gets to 28,000 mark it takes off like a rocket ?

Is this standard setup ? nothing more anoying than putting your foot down only to have to wait that vital second for the revs to get up.

I'm not at all familiar with mechanics but still Any help greatly appreciated.

I love the Alfa's style and handling. Just love getting behind the wheel of this car, such a pleasure. I viewed some newer cars before deciding to get this. They did not come anywhere near the mark.

[David C]

Hopefully you mean 2300-2800rpm, not 23000-28000rpm...!

At various speeds there are changes to the inlet manifold length and the inlet cam position.
could be that you are fealing.

[symon]

I think this "Flat spot" is caused by the way the ECU controls valve overlap, and is there to reduce emissions, especially when cold. A remap should get rid of it.

Thats what someone else told me anyway.

Simon.

[jug]

it depends how an engine is set up, the twinspark is biased towards higher rpm, that always comes at the expense of low rpm, but it does mean the engine loves to be pushed and is happy to rev to 7500rpm, unlike most petrol engines that give up at 6500rpm or less.

[Jonsiv]

Thanks for the feedback,

So if I was to get it remapped to increase acceleration and get rid of the flat spot, will that effect the overall speed much ?

[jug]

yes, an increase in power will mean an increase in speed. some mods sacrifice power for torque or vice versa, a remap improves both, so you get better acceleration and top speed.

[Dr GTA]

How would top speed be affected?

You don't change gearbox ratios, so 4000RPM in 5th is still 80.

[symon]

Originally Posted by OperationAlfa

How would top speed be affected?

You don't change gearbox ratios, so 4000RPM in 5th is still 80.

Your car must be shorter geared than mine, as mine is doing around 3600rpm at 80mph in 5th.

The reason the flat spot is there apparently is to allow the car to pass the emissions test if it was tested with a cold engine. As people rarely get their cars MOTed with a cold engine its use is limited, hence the reason most remaps get rid of it.

[Dr GTA]

Originally Posted by symonh2000

Your car must be shorter geared than mine, as mine is doing around 3600rpm at 80mph in 5th.

The reason the flat spot is there apparently is to allow the car to pass the emissions test if it was tested with a cold engine. As people rarely get their cars MOTed with a cold engine its use is limited, hence the reason most remaps get rid of it.

Well Jamie porter was driving at the time. He stated 4000RPM in 5th is 80..

Are the 2.0 gearboxes different? Anyone? I know they were in the 155's.

I've had my car to 140 (on a private runway). The topspeed is meant to be 130 though.

[David C]

Originally Posted by OperationAlfa

Are the 2.0 gearboxes different? Anyone?

Different to what?

[Dr GTA]

Originally Posted by David C

Different to what?

to the 1.8's

[jug]

Originally Posted by OperationAlfa

How would top speed be affected?

You don't change gearbox ratios, so 4000RPM in 5th is still 80.

when you're in top gear you cant hit 7500rpm, but with a remap you can get closer, since the gear ratios remain the same that must be a higher speed.

the problem is that to get a little bit extra top speed you need a fairly large extra amount of power. by that i mean a 10% power increase wont mean 10% higher rpm is achievable.

[Dr GTA]

Originally Posted by jug

when you're in top gear you cant hit 7500rpm, but with a remap you can get closer, since the gear ratios remain the same that must be a higher speed.

the problem is that to get a little bit extra top speed you need a fairly large extra amount of power. by that i mean a 10% power increase wont mean 10% higher rpm is achievable.

Ahh, of course. Cheers

[jug]

Originally Posted by OperationAlfa

Are the 2.0 gearboxes different?

yes, they all have slightly different ratios. i'm going to fit a 1.6 gearbox to my 1.8, i've done similar things on cars in the past, it never fails to please.

i dont have the full ratios to hand, but briefly:

1.6
top gear ratio 0.97:1
final drive ratio 3.73:1

1.8
top gear ratio 0.92:1
final drive ratio 3.73:1

2.0
top gear ratio 0.95:1
final drive ratio 3.56:1

to get an idea of how difficult your engine will find turning the wheels in top gear, multiply the 2 numbers together, higher number means easier to turn, and hence you can feel more pull from the engine.

if you calculate the numbers for every gear (not provided here, but readily available if you google it) using every gearbox you can decide what the differences will be in a comparable way to decide if its a worth while difference and what you want to achieve.

notice the 1.6 and 1.8 are very similar, but the 2.0 has a significantly different final drive ratio. thats the clue that sticking the 2.0 box on a 1.8 would have bad consequences (which you expect) because the 1.8 wont have enough torque. if you like a lazy style of driving then this could suit your needs, if you prefer more rapid acceleration then go for a 1.6 box.

i did the maths a few weeks ago, the 1.6 box is definately a worth while mod. in the past i've seen better gains than a remap simply by fitting the gearbox from a smaller engined model. i dont expect that type of gain in this situaiton because the differences are not that significant, but its still going to make the car feel lighter on its feet and make for a more involved driving experience, it wont suit everyone but its exactly what i'm looking for. combined with a remap it should satisfy my needs.

[Dr GTA]

Interesting stuff

[David C]

Originally Posted by jug

i did the maths a few weeks ago, the 1.6 box is definately a worth while mod.

There is also a 1.4TS box from a 145/146

[jug]

wow, i'm now nursing a semi looking for the ratios

[Dr GTA]

Originally Posted by jug

wow, i'm now nursing a semi looking for the ratios

Lol! David probably has them somewhere. In the big alfa paper cabinet

[jug]

ok, the 145:
top gear ratio 0.85:1
final drive ratio 4.11:1

thats very different!

4.11*0.85= 3.4935


compared to the 1.8 which is 3.4316
and the 1.6 that is 3.6181


the 1.4 box is very close to the 1.8box on final gear, which is what i'm after (to save petrol, the race is won by the time you select 5th), if it also has shorter 2nd and 3rd then i think we have a winner.

on the other hand, with the 1.6 box fitted you can quickly build up speed at 70mph without changing down to 4th.

[Jonsiv]

All this technical goes over my head but thanks for the advise

Think i got carried away with the zero's on topic though

Their are a few tuning specialist near me so I think a visit is called for in the next few weeks.

What are generally the best mods to go for first ? I know its going to depend on what I want to achieve and get out of it.
My gf's 206 gti beats the Alfa for acceleration and the performance overall is a close match.

So guess a remap is first, then what ?? the intake ? suppose my fuel consumption will also increase with a remap ?

thanks again guys.

[gazza82]

Intake changes don't appear to make a big difference .. but an exhaust probably would ... with a free-flow cat/de-cat.

On the intake, the resonator unit that is before the air-filter could go and be replaced with the GTA intake pipe. Should make it a bit more responsive. This is located inside the wing area and there's a how-to on changing it on my website under Hints & Tips ... albeit the older V6 intake pipe. Procedure is same for GTA just different part(s) .. I've added the list at the end.

What makes the 156 really move is a properly working MAF!

[Jonsiv]

Spoken to a local dealer and they said remapping a petrol engine would show very little improvement. Has anyone had it done to a 156 2.0TS ? if so what difference if any did you see. I don't want to wasting a few hundred on this if it really isn't worth it.

thanks

Originally Posted by Jonsiv

Spoken to a local dealer and they said remapping a petrol engine would show very little improvement. Has anyone had it done to a 156 2.0TS ? if so what difference if any did you see. I don't want to wasting a few hundred on this if it really isn't worth it.

thanks

You should expect the following:

Most 156 2.0 TS suffers from a sudden drop in torque around 2200 rpm. This can be eliminated and makes the car easier to use in f ex city traffic.

7-17 bhp gain. Max output possible on stock engine being around 165 bhp. A lot of 2.0 TS drive around with less then the 150/155 bhp they are supposed to have. Average output after a remap is I believe 163 bhp.

Slightly better milage is also quite possible.

[sensingsys]

Originally Posted by Jonsiv

Spoken to a local dealer and they said remapping a petrol engine would show very little improvement. Has anyone had it done to a 156 2.0TS ? if so what difference if any did you see. I don't want to wasting a few hundred on this if it really isn't worth it.

thanks

People who have not had remapping done are keen to say that it is not worthwhile on a non-turbo car. I had my 2.0 TS remapped by Nigel of Angel Tuning, far better acceleration throughout the rev range including far more willing to rev over 6,000, more flexible around town, no downside, well worth the £300 (cheaper now) it cost me. Indeed I cannot imagine any other way you can get such a performance boost for £300.

I get around 26 to 28 mpg (I run a spreadsheet to check my fuel consumption) using very spirited driving, that's about the same as before the remap but using a lot more power - I get roughly 33 mpg when cruising at around 70 mph on the continent.

The two other engine mods I have are de-coned & a GTA intake.

[Dr GTA]

Originally Posted by Peter K

You should expect the following:

Most 156 2.0 TS suffers from a sudden drop in torque around 2200 rpm. This can be eliminated and makes the car easier to use in f ex city traffic.

7-17 bhp gain. Max output possible on stock engine being around 165 bhp. A lot of 2.0 TS drive around with less then the 150/155 bhp they are supposed to have. Average output after a remap is I believe 163 bhp.

Slightly better milage is also quite possible.

I could not live without the remap on my 1.8.... It might be only a slight increase, but the difference in pulling power is great.