How much hp can you get out the stock aan motor?

[CodeOfDaStreets]

Ive been into dsm"s for a while now and kinda want to move onto a diffrent platform of car now. Im planning on buying a 90 quattro coupe or sedan and doin a aan swap from a c4 s4 us version. Id like to know how much hp I can get out of this motor safely. And im not new to modding car so I know what mods I need for the power goal the motor is capable of. Also what transmission would be the best for drag racing, I"d want to know what would be the most durible one.. Thanks

[Jamo]

what do you mean when you say stock? stock rods?

[Ross]

About 400hp is a safe limit... There are those running closer to 450hp on a stock motor without issue, but that is starting to push the envelope a bit. MAF wires and rods if you get a bit of knock. If you were to stick a set of forged rods and put the maf pressure side, you are looking at more like 600hp.

[prj]

There is no reason to move the MAF anywhere, it won't magically read more on pressure side and it'll still max out at about 370hp.

There are enough solutions to map these cars properly above, but consider the max on stock engine with custom mapping about 440-450hp.
Change the rods, and you are looking at upto 650 hp.

This obviously assumes that the engine is perfectly healthy to begin with and that the mapping is well done. You can always blow up your engine with stock turbo.

[CodeOfDaStreets]

Im assuming ud have to change head gasket and head studs also?? But yeah stock motor was just curious of the limit. If i change the rods Id might as well change the pistons? Btw that is the stock compression in these motors?

[Jamo]

You don't need to change the pistons they are good for 600 bhp, you should have the metal head gasket again if so no need to change.

Head studs ARP are a good idea to stop head lift but again many cars know to run fine on stock, basically these engines are bomb proof if done correctly.

Stock CR is listed as 9.3:1 a lot of people drop that with gasket to 8.5-8.6:1 to allow for more timing up top

[Thuppu]

If your goal is not above 600+hp it's no point to change pistons and drop the CR.

[driftin jo]

I wouldn't say 450hp is the limit more that there is a limit of torque that would be sensible
on stock rods.
If you say that 400f/lbs of torque is safe with the stock rods then if you make this at 5252 rpm you have 400 HP. This would be using a turbo with good low rpm boost capability something similar to the RS2 turbo for example. However if you were to use a turbo that would allow enough flow at 7000 rpm to produce 400 f/lbs of torque the you would have 533 HP, the rods would see no more stress than they did at 400 HP.
It's all about what you want , many people including myself don't think it is worth while having a tune with no low down torque as this is what makes these engines/cars so drivable without having to the rev the nuts off them before they get going.
What I'm saying is it is possible to make 500+ on standard rods but there is a sacrifice in that you cant have low down power as well as the turbo required would no be able to do this.
So if you don't mind turbo lag until 5000 rpm the limit is much higher than 450 hp.

[Rocco]

I wouldn't say 450hp is the limit more that there is a limit of torque that would be sensible
on stock rods.
If you say that 400f/lbs of torque is safe with the stock rods then if you make this at 5252 rpm you have 400 HP. This would be using a turbo with good low rpm boost capability something similar to the RS2 turbo for example. However if you were to use a turbo that would allow enough flow at 7000 rpm to produce 400 f/lbs of torque the you would have 533 HP, the rods would see no more stress than they did at 400 HP.
It's all about what you want , many people including myself don't think it is worth while having a tune with no low down torque as this is what makes these engines/cars so drivable without having to the rev the nuts off them before they get going.
What I'm saying is it is possible to make 500+ on standard rods but there is a sacrifice in that you cant have low down power as well as the turbo required would no be able to do this.
So if you don't mind turbo lag until 5000 rpm the limit is much higher than 450 hp.

+1

[Ross]

There is no reason to move the MAF anywhere, it won't magically read more on pressure side and it'll still max out at about 370hp.

Im talking about the wire getting ripped out due to air velocity. I thought that was the reason for moving it to the pressure side, as well as the stalling issues it seems to solve? Obviously 500cfm of air at 1bar travels thru the maf with higher density but less velocity than at 3bar, but i must admit i have not modelled the drag caused by the MAF wire in these scenarios, just going by others experiences...

[CodeOfDaStreets]

Whats the diffrence from the us and euro aan motor?? is there a diffrent engine code??

[merlin's S4]

Whats the diffrence from the us and euro aan motor?? is there a diffrent engine code??

Nothing! They're exactly the same.

[quattrofrank]

You can use stock pistons up to around 750hp. Head studs can also be original parts for as many hp as you want almost

[Jeltuh]

That MAF issue, can't that be solved with programming the ECU to Speed/density. Than you could use an other temperature sensor (i.e. from a BMW M50) in your pressure side (IM).

I know BMW ECUs can be programmed to Alpha/N, don't know if that can be done for SD. All the sensors are present on a S2 engine though.

[prj]

That MAF issue, can't that be solved with programming the ECU to Speed/density. Than you could use an other temperature sensor (i.e. from a BMW M50) in your pressure side (IM).

I know BMW ECUs can be programmed to Alpha/N, don't know if that can be done for SD. All the sensors are present on a S2 engine though.

I have a ready solution for up to 700hp with stock ECU...
Alpha-N will not work with a boosted engine.

If you want Speed-Density, then it is better to buy a Speed-Density ecu. Tatech and VEMS make a pnp kit.

If you say that 400f/lbs of torque is safe with the stock rods then if you make this at 5252 rpm you have 400 HP. This would be using a turbo with good low rpm boost capability something similar to the RS2 turbo for example. However if you were to use a turbo that would allow enough flow at 7000 rpm to produce 400 f/lbs of torque the you would have 533 HP, the rods would see no more stress than they did at 400 HP.

I believe your logic is flawed.
If one would follow your logic, then in an otherwise ideal engine there would not need to be a rev limit.
The stress on the rods increases with RPM, although whether it matters in this case is a different question