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Monster CIS, is it a Miller Cycle?

Hi everyone, it has been a while.

Quote:
...627HP@5300 Torque: 658Lb/Ft(892Nm)@4600 on mainly stock 930 Euro components and on pump gas - well, 98 octane over there...

I have long wondered about the "Monster CIS" motor and how such achievement was even possible. (I know how to get the fuel!)

This builder achieves more efficiency out of a two valve air cooled motor than most builder's seem to get from even a water cooled four valve motor. He does it at a very low rpm and can run up to 1.3 bar boost with a single plug without issue.

Well, I am wondering if he might be a student of the "Miller Cycle" (MS) motor.

Standard 4 stroke motors have an expansion stroke that is very close to the compression stroke in length.

With a Miller the compression stroke is shortened. Shortening the compression stroke reduces the power lost building compression (pumping losses). It also can makes for less heat from compression. As we know heat is one of our biggest issues.

If the combustion chamber is not reduced in size like is typically done on a MS motor, that would allow much more head room for boost.

Of course, the power stroke could also be lengthened to capture more of the combustion cycle's power. This would move the TQ peak to a lower rpm as seems to be the case with the build.

The Monster Builder has noted that he uses a custom cam of his own design.

He also used stock displacement, stock euro headers, a custom turbo for the application, an intercooler of his own build, and a boost management strategy (to 1.3bar tapering to .9 bar) to stay within fueling limits.

So here is what I am thinking he may have done besides building a great motor with an efficient intercooler.

He may have shortened the compression cycle and lengthened the power stroke / expansion cycle. Not sure if he reduced the compustion chamber size.

With this he would need a special turbo matched to the build. Said turbo would have to have a smaller hot side than usual to allow for early boost he achives and work with the lower exhaust gas production at lower temps.

This might fit how he can make so much HP with the stock headers.

It also would have to have a larger compressor to support the higher HP levels.

In my mind I wonder if this is the last piece of the puzzle?

The best.

Monster Build:
Cis monster

Miller Cycle"
Miller cycle - Wikipedia, the free encyclopedia

Quote:
Originally Posted by zcoker View Post
I don't know if this site has been posted here before and it probably has yet I've never come across it: 627HP@5300 Torque: 658Lb/Ft(892Nm)@4600 on mainly stock 930 Euro components and on pump gas - well, 98 octane over there.

SpezialMotorer-Engine Development Click under project section.

I know that many here place solid limits on the CIS system and I'm just learning about it myself but this says otherwise.




If I know the Swedes like I do with bmw's, this is true information. We doubted a long time their claims on some of their bmw motors but they have some s38's over there pushing 1500hp and running 7's in the 1/4 mile - varied. I guess those long, cold winters over there afford them plenty of time to tinker and build these monsters. Very interesting to see some things taking way beyond the norm (like they always seem to do) in spite of the speculation and doubts. I sure would like to see more info on this build but the Swedes are quite tight lipped with their projects.

Last edited by 911st; 08-29-2011 at 04:58 PM..
Old 08-29-2011, 04:51 PM
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Max Sluiter
 
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So basically an interesting set of cams? If he held the intake open as the piston came up the CIS would not like the reversion. If he closed the intake early then the gas expands but then compresses as the piston passes bottom dead center and starts coming up.
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Old 08-29-2011, 05:56 PM
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Great question.

We have all heard that CIS does not like an aggressive cam and I do not think you could get this to work on an SC.

However, the 930 is a bit of a different animal.

First, I doubt the Monster Builder went so far down the Miller Cycle path to be actually be a Miller Cycle motor.

Only that it might give a clue to how he achieved such a high level of efficiency measured by the gross TQ he achieved at his peak boost level.

Also, I suspect that once the turbo is making boost the pressure will work to overcome the intake blow back.

It is only a guess but CIS could even benefit from some of the intake blow back that comes with the Miller Cycle. It just might improve atomization some which is a problem at low rpm with a very low compression CIS turbo motor.

As to creating issue with the metering function, the 930's is very isolated compared to say an SC.

There is lot of volume between the intake valve and the metering plate with about 5 feet of large diameter tubing, metering assembly, and the intercooler. Plus there is the turbo's compressor mass to further buffer any pressure wave potential.

Just a guess.
Old 08-29-2011, 06:55 PM
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OK, I see what you mean.

I hate CIS anyway, I would just do EFI. Variable valve timing and lift are even cooler but that means a water cooled car short of some insanely expensive home-made system.

Must be the engineer in me.
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Old 08-29-2011, 06:59 PM
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Fleiger,

All the reasons you note is what makes this build so interesting. He pretty much out does motors with all the goodies noted.

Most high HP builds use RPM to make big HP. He seems to do it by making much bigger TQ.

I wonder, if the intake valve blow back from a Miller Cycle might not be less that that we might see from the exhaust blowing back through the intake valve at times with an overlap cam like a C2 or more aggressive overlap cam.

With a turbo there can be a lot more pressure in the exhaust side than the intake side.

The Monster Build may still be a non (exhaust to intake valve) overlap cam.

Part of the key in getting a Miller Cycle approach to work is probably going to be in the turbo sizing and the tune.

Last edited by 911st; 08-29-2011 at 07:25 PM..
Old 08-29-2011, 07:23 PM
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Do we have any real world timeslips of said cars? Maybe he just has a very happy engine dyno? Look at the top end. You said 0.9 bar and the pic shows 550chp. Possibly doable with low pumping losses but if tuned for low end does seem too much?
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Old 08-29-2011, 07:30 PM
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There was a lot of questioning as to the validity in the original thread. (See link above.) Even if we discount it 10% or so this is an amazing amount of power.

Yes the HP is big but when you dig into the TQ is when things get wild. TQ peak is at a boost level of about 1.2-1.3 bar if I recall correctly. On euro pump gas without detonation issues. He gets more power out of every stroke than any other builder. And he does it without running up against the typical thermal limits that come with an air cooled motor.

Part of that can be attributed to a very efficient intercooler, turbo, and tuning but that is not enough to run at those levels and not toast a motor. Shortening the compression stroke would have the effect of lowering the effective compression.

For example, the Prius which uses a variation on the Miller Cycle would have a normal compression of over 13/1. However it runs on regular gas because it's effective compression ratio is closer to 10/1.
Old 08-30-2011, 06:56 AM
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He's running more boost than that in the mid range, when i spoke to him a few years ago he wouldn't say the exact amount, but i was assuming a 1.5bar minimum peak, his words were "a LOT of boost in the mid range"
He was explaining to me that as there is so much fuel available in the mid range he can run plenty of boost there, and then tapers it off as he goes up...... His engine dyno will give more accurate results than a chassis dyno, look at the cooling on the thing.....
It would be interesting to know how the boost and ignition is controlled on these CIS builds?
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Old 08-30-2011, 07:11 AM
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Quote:
Originally Posted by JBL930 View Post
He's running more boost than that in the mid range, when i spoke to him a few years ago he wouldn't say the exact amount, but i was assuming a 1.5bar minimum peak, his words were "a LOT of boost in the mid range"
He was explaining to me that as there is so much fuel available in the mid range he can run plenty of boost there, and then tapers it off as he goes up...... His engine dyno will give more accurate results than a chassis dyno, look at the cooling on the thing.....
It would be interesting to know how the boost and ignition is controlled on these CIS builds?
John--

Since you are over the pond already..You should pay him a visit and play PORSCHE INSPECTOR and INSPECT his paperwork und German carz....Need video .....

Walt
Old 08-30-2011, 07:16 AM
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When i blew up my 930 lump i was seriously considering sending it to him, he's well respected by a lot of people over there, the guy clearly knows his onions...... It's a stonking amount of power for CIS, no mistake there.
The engine may not deliver the power to everyones taste, it'll be useless in anything other than dry conditions. I also don't doubt it gets pretty hot if pushed hard on long runs, i'd really like to know more about how he controls everything, whether there is any knock control, whether it pulls boost or timing if the temps go too high........ That's the biggest worry with CIS, there's very little to prevent everything melting if something is wrong. He has to have some type of management/safety in there. A cold winters day is very different to a blazing hot summer here in Europe, it can't just be set up for 20-degC conditions and left. The fact that it's varying the boost through the RPM range says it's got some control, i'd love to know how it's all set up.
Maybe on my next jaunt over on the continent i'll swing by and pick his brains
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Old 08-30-2011, 07:35 AM
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I Think there are a couple of Swedes on this board. I also think at least one of them has got 1st hand experience. Let's see if can have them chime in. It been a while since the last discussion on this.

Also, if I remember correct the Kenne Bell book has got some about the miller cycle. Just FYI! If you are a rookie like me trying to understand.

Thanks for bringing up these topics. I learn a lot from it.
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Old 08-30-2011, 10:48 AM
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Quote:
Originally Posted by JBL930 View Post
He's running more boost than that in the mid range, when i spoke to him a few years ago he wouldn't say the exact amount, but i was assuming a 1.5bar minimum peak, his words were "a LOT of boost in the mid range"
He was explaining to me that as there is so much fuel available in the mid range he can run plenty of boost there, and then tapers it off as he goes up...... His engine dyno will give more accurate results than a chassis dyno, look at the cooling on the thing.....
It would be interesting to know how the boost and ignition is controlled on these CIS builds?
Yes for sure Mike Seven is using a lot of boost in mid range.

I even think is using more than 1.5 bar in midrange ( maybe with lower CR and keeping regular timing ).

The turbo he is using is one of the key point ( Intercooler helps as well) . A huge turbo which start to spool at decent RPM but which need about 1500 RPM (!) to reach the desired boost level @ 4600 RPM.... short lag is certainely not the goal (but efficiency and flow capability are ).

The cams he is using are not exotic.
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Old 08-30-2011, 01:31 PM
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Quote:
Originally Posted by jsveb View Post
I Think there are a couple of Swedes on this board. I also think at least one of them has got 1st hand experience. Let's see if can have them chime in. It been a while since the last discussion on this.

Also, if I remember correct the Kenne Bell book has got some about the miller cycle. Just FYI! If you are a rookie like me trying to understand.

Thanks for bringing up these topics. I learn a lot from it.
I know Micke. He's a true wizard when it comes to 930-935-962 engines and others.

Here's a video from one of the "other" engine builds he's been involved with lately.

V.S Motor BMW M5 V10 Twin Turbo - Dyno - 1851bhp/1817Nm@1,8bar-Methanol - YouTube
Old 08-30-2011, 03:34 PM
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Quote:
Originally Posted by zeb930 View Post
I know Micke. He's a true wizard when it comes to 930-935-962 engines and others.

Here's a video from one of the "other" engine builds he's been involved with lately.

V.S Motor BMW M5 V10 Twin Turbo - Dyno - 1851bhp/1817Nm@1,8bar-Methanol - YouTube
Hejsan

I thought I remembered you giving inputs on this earlier on, but wasn't sure.

It would be nice with some info on this. So far those numbers seems magic.
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Old 08-30-2011, 03:43 PM
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Quote:
Originally Posted by jsveb View Post
Hejsan

I thought I remembered you giving inputs on this earlier on, but wasn't sure.

It would be nice with some info on this. So far those numbers seems magic.
Hej

You remembered correctly.. My friend had one of mickes earlier CIS engines and that produced 554hp/796NM and the "cis monster" engine was built a couple of years later so for me 75hp extra after a couple of years of additional tweeking doesn't seem more than right.. (probably not dynoed on the hottest day of the year either)

Probably shouldn't go there but I know he runs GT2 evo cams and a larger modern turbo now on the "cis monster" and has just managed to find a way to have fuel enough for this set-up..
Old 08-30-2011, 04:16 PM
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Just realized me saying magic may indicate that I don't believe in the numbers.
This is not the case. I have no reason not to. I am just astounded by his work.
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Old 08-30-2011, 04:30 PM
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Quote:
Originally Posted by 911st View Post
Hi everyone, it has been a while.
Welcome back. You always come up with some interesting discussions, I just wish I was bright enough to add to them.
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Old 08-30-2011, 06:08 PM
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The following is quote from the Monster Builder:

Quote:
Hi Leonard.
I have reached 648hp with my CIS engines the system is verymodified and
so is the engine, to reach these figures so do i only sell a complete
engine modifikation, you send me your engine and i tear it apart and build it
up agian with the right combination, if you are interested, or have some
more questions please call me on 0046 8 7784949 so can i give you some more
information if you are interested.

then

Hi,
Ok first of all so is the cis i use a stocksystem that is modified but
that is the hole secret the thing is to adapt the engine to the fuel system
not the way around that is what is normally to do, that is because if you
build the engine more fre flowed so will it peak around lets say 6000 to
7000rpm if you do that so will the fuel and flow curves not fit togheter, the
boost curve is not linear i boost 1,2 between 3500-5000 and then 1,0bar from
5000-5400rpm and then it sicks slowly at the higher rpms, i do not now
the freight costs but i can check if you are interested, the export price for
my 600hp+ CIS engine is 35000$ us and its totally rebuild i work with
every piece on the engine and its also dyno tuned so you get some figures as
well, nice talking to you.
My two cents for what it is worth:

He says he is making that power at a max boost of 1.2 bar and then tapers it off to stay within the gross fuel delivery limits.

With the cams he was runing back then he made peak TQ at 4500rpm. A more agressive cam would probably move that up further. I think C2 cams make peak TQ around 5200rpm on a 930 and GT2 EVO's at around 6000rpm.

I know where he gets his fuel distribuitor's built but I suspect he breaths on the fuel pumps, injectors, and WUR to get to that level and may even blueprint the metering pin travel.

I also suspect he gets more power from the the fuel available than any other builder and there in lies his 'magic'.

I belive peak TQ is where cylinder pressure is at it's highest and where each stroke is making its most power. When you move the TQ further up the RPM range you loose efficency as the power stroke is shortened and there is less time between events with less time to shed heat. You do gain HP as there are more power strokes. Move it down the RPM range and you can increase TQ potental.

Seems to be more of a high performance tractor motor than a race motor.


Last edited by 911st; 08-31-2011 at 01:14 PM..
Old 08-31-2011, 12:43 PM
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Quote:
Originally Posted by jsveb View Post
Just realized me saying magic may indicate that I don't believe in the numbers.
This is not the case. I have no reason not to. I am just astounded by his work.
Me to.. His flat-fan set-up is just one of his creations thats just sick. Titanium axles etc not something you throw together in a weekend.

flatfan 1
Old 08-31-2011, 01:48 PM
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Power is limited by fuel delivery rate. The amount of power the engine actually puts out after frictional losses will be greatest at a lower rpm for a given constant fuel delivery rate. This is because the frictional losses increase with the square of the speed while the power increases linearly with increasing engine speed (rpm) with a given amount of torque.

Therefore, if you can get enough air in per stroke to burn the maximum fuel delivery rate then you will make more power at a lower rpm while also making more torque for the same reasons of friction's relation to engine speed.
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Old 08-31-2011, 05:26 PM
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