250HP+ 1600DP Mouse Motor

[Kalle]

Hi Mario,

Imagine this; seal your turbo outlet completely and measure the back pressure again. It will go through the roof. Then drill a small hole in the seal and measure again. Still very high. A bigger hole, a little lower. Remove the seal completely and it will be a low as it can be and the back pressure you see now is due to your turbo and exhaust.

This is for your eyes only Below you have two pictures and a movie of the Audi S6 2.2 that belongs to the driver of the Skinne Beetle. It serves as a daily driver and he also race the car on street legal events and on ice. It is one of the fastest car on ice with a top speed of 205mph and you can see that run if you click on the youtube link below. Racing a car on ice is the ultimate test for a turbo car. Cold temperature in combination with high rolling resistance due to the spiked tires and high boost over a long distance;

https://www.youtube.com/watch?v=MNkBK6Ug2Ms

The Audi engine is built by Skinne and here you have two pictures from the Dyna Pack dyno. First @ 41 psi and take a look at the two pressure lines:

Ladetrykk = Boost pressure
Baktrykk = Back pressure



And @ 52 psi and again take a look at the two pressure lines:



The result was 964 whp - 4wd. Not too shaby.

Back to my mouse. I spent some time in the garage this weekend and the result you can see here:



I copied the CB Mini Wedge intake. I have also received 4 1.55 Rockers from JPM and that should give a lift of around 13.85mm / 0.545"

-K-

[Wally]

Hi Kalle,
Very cool graphs! I have measured back pressure myself from the first time I ran my first turbo. I had 3 different turbo's on the same engine and the difference in back pressures and power output was 'interesting' to say the least. Low back pressure in itself is rather easy to get: just mount the biggest turbine wheel with the biggest A/R turbine housing you can find in the catalog and voila: back pressure ratio's of 1:1 or better.
The other effect of this can be easily predicted as well: spool is extremely late, i.e. a huge turbo lag.
The key is to find the 'optimum' in these conflicting parameters: quick spool and high max hp output. Besides an optimum sizing (often underestimated) of your turbine side to find the best match, high tech is your friend to gain on both parameters (spool and power).
Examples of the parameters of just a better designed turbo for a given hp-output will be seen on: Light weight turbine and compressor wheels, extremely low resistance bearings, a better (BOV) design and more advanced Aero.

All of these usually cost more $$, but sometimes you can choose between equally expensive turbo's and pick the better one based on the above features.

PS: Interesting to realize is also that once you have sunken in that if boost pressure on the intake is about equal (1:1 ratio) to back pressure in the exhaust side, that your engine operates basically as a....N/A engine!
Actually, I am so bold to say that most N/A engines don't get 1:1 ratio, but have an exhaust system that gives them a higher back pressure then atmosferic!
Another reason why n/a engines are not always very efficient

I like the porting done! I am sure you will let the wider head opening be followed throughout the intake manifold (unless these are already that size, can't remember myself)

[MarioVelotta]

Really nice info Kalle!!!

[Kalle]

I like the porting done! I am sure you will let the wider head opening be followed throughout the intake manifold (unless these are already that size, can't remember myself)

Was that a test Wally? There is no point opening the head if the manifolds do not match. They have plenty of material and it is a time consuming job to open them up all the way. The head side is still the narrowest point of the intake channel:



-K-

[Wally]

Nah, I don't need testing you

The head side is still the narrowest point of the intake channel:

-K-

Its more like that I have seen lots of extremely widend entrance ports, without matching areas further down into the head at the valve seat and guide cross-area. Even though it doesn't really hurt cuft/min (it ddoes for airspeed btw), I am sure you of all people know how important the whole path is.

On a different note: can't I talk you into changing out that humongoes turbine housing for a much better suited twinscroll version to see what that could do for spool on your tiny engine?

[Kalle]

DANG Wally! I could not agree more and when I see the typical Big Beef manifold on a NA engine I just know that the engine has a lot of unleashed potential. And as I have always said, a good NA engine will make a fantastic turbo engine

You are of course right regarding my turbo as well. I guess I just have to increase the boost to make sure the turbo get to the area in its map where it is most efficient. And to ease the spool (not that I felt that I had a problem with spooling it up as soon as I figured the settings) I can always mount a small nitrous jet again.

Decisions decisions....

-K-

[madmike]

K, you don't really port with a drill do you

[Kalle]

K, you don't really port with a drill do you

That would take too much time. I use the drill to fluff after I have used the blue air hose you can see in the picture together with this one;



-K-

[madmike]

That's better Mine's electric 1/4 hp
foot control and very controllable speed wise, I use to do a lot of 2 stroke Motocross cylinders

[Kalle]

Nice! Those would probably cost more than my engine

-K-

[Wally]

I can always mount a small nitrous jet again.

Decisions decisions....

-K-

Easy decision of course: keep it simple without solenoids and extra lines...

An equal length 4 into 2 exhaust header on a type 1 is not always simple I realize, but at least that hasn't got moving or electrical parts in it

[Kalle]

If simplicty was my main priority I would install the nitrous again. I have the bottle bracket in the car. The nitrous solenoid and the jet is on my work bench and the nitrous relay already connected. All I have to do is one click in the map and the ECU will handle the rest.

-K-

[madmike]

-k-, they aren't that expencive get them here:
C.C. Specialty 6035 C.C. Lane Lawrenceburg,Tennessee 38464
1-800-762-6995

[Wally]

Last week Kalle participated in the SCC 2016 raceweekend at Gardemoen airport dragway, Oslo, Norway and I went over to have a look





and drove an easy 10.7 at 204-ish km/h when the launch was decent (1.47 60ft)


Kalle's right hand side rear tire after the 1.47 sec 60ft:


Great event, great weather, great turn-out and super friends all around!

[MarioVelotta]

One of these days I'll get this engine of mine together! I just need to go back to a regular job so I have some time to myself

Did you make any changes over the winter?