Here are some of the answers, but maybe not all of them to the power questions I've had with Nowack since l had my M5 converted late last year, and some of them resolved????
I emailed over to them some of the dyno read-outs l had got in Orlando just a few weeks back. I called them a few days later, as to give them time to have a good look at my findings !!!
So to draw a picture, my base numbers before the conversion, were around 345 SAE RWHP and 335 lbft for torque.
My new numbers now after the conversion are 385 SAE rwhp and338 lb....so a plus 40 hp gain and less torque then what it had before the conversion..... l had to ask myself.. WTF as Nowacks claims are miles higher then those numbers even if they were converted to their larger DIN format of power measurement numbers.
It's so easy to think you've been had, when you see results like that.
When l emailed them the dyno sheet read outs I converted them into their "DIN" hp/ps format for their ease of use. Our SAE hp rating is just a bit lower then DIN in hp & tq numbers.
So to look at all numbers in DIN from now on will make it just a bit easier to compare to Nowacks tested results. So then in DIN all l could muster from the conversion was a converted and corrected max of 400rwhp DIN...(our U.S 385 rwhp SAE).
I did manage to find a max of 408 rwhp DIN using some leaf blowers (leaf hogs to be exact) in each ram duct......yes its very primitive, but it was the only way l could try and recreate (cheat), and to see if some sort of forced air flow could produce more power over normal dyno testing procedures, and to even try and get close to Nowacks 470 rwhp DIN claims??.
The blowers did give some extra torque.. 20+lbs in the middle rpm's... 4,000 - 5,500 rpm to a high of 353 DIN @ around 5,000rpm (+12 ft pound over OEM), Torque on the "leaf blown" run Vs and the "normal" tested run, then began to taper back towards each other from 5,500 - 7,000rpm. The "leaf blown" HP numbers only started to climb above the "normal" converted runs, at around 4,500rpm and stayed that way with ease till 7,500 rpm.
So l was not to count the "Leaf blower" tests as any real break through in gaining much power over stationary "normal" testing. The test was a bit more of a cheap experiment, but l think it was a very worth while one. l was really expecting the "blowers" to have made more power then they did though???.
So to see the new maximum peak torque number being 5 lbft LOWER then the old OEM figure, was one hell of a "scratch your head deal" The torque curve was much more up and down, and most of the time spent it climbing and falling, and always under the very flat OEM torque curve readings of the stock M5 till around 5,000rpm.
This lower torque maximum in the Nowack would/could be explained as the whole exhaust system is larger in diameter and the back pressure being cut by half, could be the main contributor to that, but l'm not sure... what do ya think ???.
Torque on the N500 (normal testing) touches almost it's high point at 3,200rpm (330lb) very briefly but gets to it's actual peak of (338lb) @ 5,000 to 5,000. That might sound good but it has to fall 25lb in between to 305ft @4,000rpm to climb back up above 5,000rpm.
Torque only begins to flatten out from 4,500 - 6,000 RPM and the N500 has as much torque @ 6,000 rpm as the stock M5 has @ 5,000rpm, but thats to be expected as HP is still on the climb so torque is very relevant in that aspect.
On the HP front the Nowacked M5 makes less power on a dyno from 3,200 - 5,000rpm...(there's that low dipping patch again) then the OEM....about 25Hp @4,000 (low point).much like the torque curve is low at the same points, but by that 4,000 rpm point it starts to fly up and crashes through the stock tests by 5,000rpm.
So lets get to the Apples Vs Nowack HP difference.....
I found out that the HP results Nowack got for my engine was NOT from what we call "normal" dyno testing procedures.....shock horror.
I was told they have a very $$ and complex air flow system in their shop that supplies large amounts of air (not sure of what speed) to the engine through it's full maximum rpm range. This seems to make sense, and more then likely explains why their numbers are so high, and mine to be so low as a comparison. But l can't work out how they still said they got 470 rwhp DIN form my engine.
They said that when the M5 was first in it's R&D stages, they were able to read (software) the amount air flowing through the system at any given time and speed, and as speeds increased so to would the amount of air flow and the related pressure in and out of the system. The OEM ECU wasn't really built to handle the internal changes and mixed with the new air parameters they say they could add 100hp. With this air being rammed into the engine and this being very important as speeds increased well over 100mph) it became very important for them to take advantage of this "ram effect" and change the amount of fuel being suppled at any given time. But really, the only way your going to get this 500+hp claim is only going to be possible in 5th or 6th gear at full tilt on a open road.
So this "expensive" air flow system they have in the shop is basically trying to recreate on road going conditions. I don't know how good, or accurate it is, but they're very confident that my engine creates well over 500HP, but to see all of that l would need to be doing 180 + mph. Thats not very relevant for our very slow open road speed limits in the US....... Lucky dam Germans.
What l don't get is what sort of power would the engine be making at say 7,000rpm in 3rd and 4th, as the air speed into the engine is quite a bit lower???
Looking back l guess it makes some sense, that it would be near impossible to get an extra 100hp out of an already M Powered BMW engine, and for it t be produced in a street able form, and from "normal" dyno testing procedures.
It seems and looks like false advertising to me for them to say that their M5 can make 500+hp. There's no mention at all in any promotional info that it produces it any different to the norm, or the way BMW states their 400hp.
Apples to Apples would be fair don't you think.......sorry l had to say that.
So my Nowacked engine probably has around a real 430 - 450 HP SAE at the engine, and as I've been told that number grows as speeds increase......and don't get me wrong l'm not complaining a 100%, but it's just that l wish l had known this all before the fact. This car is really only to be fully enjoyed on Germany's unrestricted roads.... .Dam that sounds like fun.
If you had a stock M5...but it's speed unlimited, and my M5 side by side and raced them from 2,000rpm in 5th till around 7,000rpm) l would say the stock M5 would pull out a gap on mine till around 100mph (160kph) mark, then the N500 would begin to make ground as quick as the stock M5 pulled away below 100mph (160kph) The effect of the rammed air at those speeds, mixed with the Vanos kicking in at 4,000+rpm is really how it takes it's full affect over a stock M5. If driven hard from a stand still how muck quicker would the "N500 converted" car be over a stock one from 60 to100, to 150 mph+...I don't know??? Just my opinion though......and l maybe totally wrong.
I am planing on getting a friends M5 soon to compare side by side some on road tests, or some data tests G-Tec or put his car on the same Dyno???
This after market tuning business (as a few members are aware) is a very interesting and very enlightening experience.. most times. I must say I've learnt plenty from all of this, and it's not all negative but it's got my attention.
I must say l love driving the car in it's converted state even if it hasn't got 500+hp from the get go, and I'm still glad l went through it all but, l would have really liked less stress through the project. Nowack need to make their customers feel more important when undertaking such a big personal/financial commitment with them, especially when your thousands of miles away and trusting them 100% with your engine or car.
Here are some of the dyno runs in DIN format if you want a look. Hit enter and they should be there....look at pics 27 to 36.