500hp
A lot of cash.....although the RS5 has a few more hp (on paper) than the RS4.
Reckon to get 500 bhp safely, you need strengthened internals, bugger all restrictions in either the inlet side or exhaust, a very trick polished and ported manifold and lastly a very extreme map. Did I mention increased fuel pump and injector sizes.
Reckon to get 500 bhp safely, you need strengthened internals, bugger all restrictions in either the inlet side or exhaust, a very trick polished and ported manifold and lastly a very extreme map. Did I mention increased fuel pump and injector sizes.
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Blue_Thunder
- Top Gear
- Posts: 1963
- Joined: Wed Nov 22, 2006 10:54 pm
- Location: UK - Liverpool
Yep ...agree. Probably around the 20K mark just for engine work (maybe more!!!)Blue_Thunder wrote:A 25%+ increase in power on a NA engine is a huge ask without looking into forced induction. Don't even think it would be possible without throwing the value of the car back into the engine.
A cheap and cheerful way of getting close to that may be to look into a decent Nitrous kit.
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BlingBling
- 4th Gear
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- Location: Bremen, Germany
The only way you can generally increase power that much N/A is by sacrificing low and mid range torque to enable a higher RPM limit.
It can be done even without increasing capacity but considering the V8 is already hitting a comfortable 8k-8.125k and almost 100bhp/litre in road trim and 414 bhp then you'd be looking at building more a race engine with considerably lighter rotating parts to try to get up to 9k maybe higher. The target of 120bhp/litre is doable but it'd mean alot of work and the rebuild frequency would drop substantually. In day to day driving the car would be slower than a stock RS4 as all the power would be up high (itd need to get to at least 5k rpm before it would start working properly)
I've had tuned N/A engines (66bhp/litre to 110bhp/litre) and you end up with a rough idle, bogging down at low speeds and generally very bad manners when driving. However get it up to the sweet spot and it's just great having a properly sorted NA engine. But if you went up against a stock car and both floored it in the same gear then the stock car would usually pull a car length ahead - the benefit from the tuning is extra power not torque so the advantage you get is that the stock car would be changing gear way before you would need to as the tuned N/A can keep producing power at higher rpm's.
FI works much better for road cars as it doesn't damage the drivability (boost lag issues aside) and you get a nice useful chunk of low down power that you lose with tuned NA. You also don't have to worry about the balance issues so much as the rev limit is unchanged.
It can be done even without increasing capacity but considering the V8 is already hitting a comfortable 8k-8.125k and almost 100bhp/litre in road trim and 414 bhp then you'd be looking at building more a race engine with considerably lighter rotating parts to try to get up to 9k maybe higher. The target of 120bhp/litre is doable but it'd mean alot of work and the rebuild frequency would drop substantually. In day to day driving the car would be slower than a stock RS4 as all the power would be up high (itd need to get to at least 5k rpm before it would start working properly)
I've had tuned N/A engines (66bhp/litre to 110bhp/litre) and you end up with a rough idle, bogging down at low speeds and generally very bad manners when driving. However get it up to the sweet spot and it's just great having a properly sorted NA engine. But if you went up against a stock car and both floored it in the same gear then the stock car would usually pull a car length ahead - the benefit from the tuning is extra power not torque so the advantage you get is that the stock car would be changing gear way before you would need to as the tuned N/A can keep producing power at higher rpm's.
FI works much better for road cars as it doesn't damage the drivability (boost lag issues aside) and you get a nice useful chunk of low down power that you lose with tuned NA. You also don't have to worry about the balance issues so much as the rev limit is unchanged.
DTM cars were getting 460hp from 4 litres.
F430, 480 from 4.3 litres.
997 GT3 RS, 444 from 3.8 litres...works out as 490 from 4.2 litres @ 116hp/litre.
My big-bore ZX12R gets 201hp from 1.287 litres but spins to ~12K rpm.
The new BMW S1000RR makes 192hp from 1 litre at ~15K rpm!
For the B7 RS4 to make 500hp all other things being equal, you'll need to get it to rev to 10K rpm.
The pistons on the car are already moving faster than a F1 cars pistons because of the stroke.
The B7 really needs a greater bore and shorter stroke.
Good luck!
F430, 480 from 4.3 litres.
997 GT3 RS, 444 from 3.8 litres...works out as 490 from 4.2 litres @ 116hp/litre.
My big-bore ZX12R gets 201hp from 1.287 litres but spins to ~12K rpm.
The new BMW S1000RR makes 192hp from 1 litre at ~15K rpm!
For the B7 RS4 to make 500hp all other things being equal, you'll need to get it to rev to 10K rpm.
The pistons on the car are already moving faster than a F1 cars pistons because of the stroke.
The B7 really needs a greater bore and shorter stroke.
Good luck!
58 C6 RS6 Stage 2+
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58 C6 A6 Allroad 2.7 TDi
Previous:
2000 B5 S4 MRC 550 Saloon
2007 B7 RS4 Saloon
1994 S2 Coupe
Many of us on here have had good results from a full sports exhaust system including 200/100cell cats, High flow filter, Ported manifold and a good custom remap, individuals on here have seen anywhere from 435 to 451ps (myself 441ps) from MRC Tunning.
Supersprint Italy was doing test with a new high flow header on a customer RS4, but the 2 prototype was loosing power possible due to back pressure, I did look into this myself at one point.
Regarding the Superchargers, 500ps would be realistic? As they say a twin screw will normally add around 60ps.
A few chargers to get your taste buds going
Supersprint Italy was doing test with a new high flow header on a customer RS4, but the 2 prototype was loosing power possible due to back pressure, I did look into this myself at one point.
Regarding the Superchargers, 500ps would be realistic? As they say a twin screw will normally add around 60ps.
A few chargers to get your taste buds going
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Money can't buy you love, but it can buy you a well sorted racecar
It would be interesting to see a UK install of the RS5 double air intake and dual throttle body on to our engines and see what effects that has.
Theoretically if for example sonnys car gains 27bhp through MRC; if the RS5 has 450 bhp and you do the same it could make 475-480 bhp but with little to no more torque?
Theoretically if for example sonnys car gains 27bhp through MRC; if the RS5 has 450 bhp and you do the same it could make 475-480 bhp but with little to no more torque?
NA?
headers, exhaust, de-cat
ECU
intakes? imo nothing to be gained
'might' get you 30 HP
the other 50 will need to come from rev's, as long as the fuel/air can keep up...but the valves may float, and then big bang and bucks
to get 10% more power, figure on at least that much rev increase, so 800, provided you can hold torque steady...
P = T x w (w = 2 Pi rps or engine speed)
in reality torque tapers off, so you may need 15%+
or rev'ing to 9200!!!
headers, exhaust, de-cat
ECU
intakes? imo nothing to be gained
'might' get you 30 HP
the other 50 will need to come from rev's, as long as the fuel/air can keep up...but the valves may float, and then big bang and bucks
to get 10% more power, figure on at least that much rev increase, so 800, provided you can hold torque steady...
P = T x w (w = 2 Pi rps or engine speed)
in reality torque tapers off, so you may need 15%+
or rev'ing to 9200!!!
have to do software also...P_G wrote:It would be interesting to see a UK install of the RS5 double air intake and dual throttle body on to our engines and see what effects that has.
Theoretically if for example sonnys car gains 27bhp through MRC; if the RS5 has 450 bhp and you do the same it could make 475-480 bhp but with little to no more torque?
the RS5 HP peak rpm is 500 rpm high, or ~7%
or 30 HP ~ 414 + 30 ~ 444
it looks like they lowered compression in the RS5 to 12.3:1 (looks like the better breathing got the torque back, still 317)
not by design, but by consequence...
my WAG is they cut the valve reliefs a bit deeper for more clearance due to the increased revs, when I did the calcs I come up with a 0.015" shorter piston overall top area, ~ 0.05 in^3 more volume per cylinder with piston at TDC, but I'm guessing that most of the volume is made up from the deeper valve reliefs...
if they made the relief cuts ~0.06" deeper, that would account for the volume increase...nothing in real numbers, but everything at 8500 rpm
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