MyE28.com

Miller,
If over 16psi makes more backpressure -- why not just use a larger exhaust to handle it all? Todd and I looked at some old ass k27 compressor maps (they could have been for the 7200 k27 model - not sure) and it looks like the k27 could handle boost levels of up to 20ish psi. Todd - do you remember the exact results? I forgot

Also - People talk about replacing their K27 core w/ a T3/4 core that should slide right in and provide better and faster boost. I've hunted the internet down for that information, and even asked Melett for information with no luck.

I personally only want to run 15psi max. I believe that the K27 is too big -- or too slow for my needs. I believe my turbo needs will be for a smaller, faster spooling (maybe sub 2k?), but lower boost turbo. Yet - we are quite screwed using the K27 unless you can find someone who wants to figure out a way to adapt newer turbos to an ancient design.

[QUOTE="Tjn182"]Miller,
If over 16psi makes more backpressure -- why not just use a larger exhaust to handle it all? Todd and I looked at some old ass k27 compressor maps (they could have been for the 7200 k27 model - not sure) and it looks like the k27 could handle boost levels of up to 20ish psi. Todd - do you remember the exact results? I forgot [/QUOTE]

That is true if the pressure is coming from the exhaust system. I imagine it's actually coming from the turbine since that turbo was designed to come on boost early, as is true with most OE turbos. If the latter is the case then a larger diameter exhaust will give you nothing except a larger hole in your wallet.

[QUOTE="345is"]sounds cool, you know with the stock k27, you will accually loose power after 16 psi, Some people may think not but I know the truth, I have the proof, Ive done enough research to know that. to run 18-20 psi on the k27 will not work, you have to retard the timing more because of the higher temps and things that goes along with more boost, but because its not making more flow but accually just making more pressure, its accually creating more heat as well. so what ive found is that if you run over 16 on a k27 you get: hotter charging air coming from the compresser, you would natually retard the timming which will also bring the temp up, less power, more strain on the engine, and eventually a blown motor due to a melted piston or somthing! sounds good eh? Not really. so If a guy has a 745i and wants more power than 330 wtq and 270 whp he will have to get a bigger better turbo and a good air to liquid intercooler. Cant wait to get a new turbo! [/QUOTE]

Im a little confused on some of your statements,
First, how does retarding timing cause more exhaust heat??? In thinking about it, retarding timing gives les efficient combustion(less burn time) so the temps would drop, no

Next, I challenge the statement that the "K27 CANT make 400hp". What are we basing that on. I was under the impression it can, just nobody has, for whatever reason. I guess no one has put the right parts on the K27 to make that much power. The turbo seems big enough, and while isn't the newest or the best, it still capable, given the right equipment around it. While Im not defending Jaurmo, I believe the M106 can make 400hp, with all the stuff he recommends, more aggressive cams being key to the whole thing, as the stock cams wont cut it to those power levels. The other problem is the auto tranny, it sucks more power than a manual, so the numbers can get there. Also, the stock A/A IC on the stock system is woefully inadequate. It needs much more. Fo every degree you lower intake temps, the exhaust temp will lower by the same amount. The stock exhaust is too restrictive also, and needs to be opened up alot, a TCD exhaust will go a long way. A larger exhaust will lower exhaust temps also, as back pressure is reduced.

Ashfins car just made a little less than the 400hp, about 380hp if my math is right and you use 20% correction for a auto tranny.

RussC

Afshin's 745i is a 5 speed. I sold him the conversion kit 4 years ago.
Todd

Retarding the Ignition timing does infact cause exhaust temps to rise. Put it this way, if you have an inefficient turbo and the compressor side of the turbo is getting out of its range, you are there for creating more backpressure, (between the cylinders and the turbo) higher exhaust temps, more heat in the charging air, ( because of a over worked turbo, if the compressor is at the end of its range because you are running it at high boost levels, you are there for spinning the turbo compresor faster which translates into higher intake temps which translates into higher exhaust temps) , so as u see using a turbo that is near the end of its range of air flow creates unwanted heat in every aspect of your engine setup. your right in saying that a turbo cam would help, but I was talking about a stock M106 with the MILLER air to liquid cooler and MAF Kit and Wastegate. No internal mods. So now with this info, what can you do? raise the boost, why, so you can blow your engine do to unsafe exhaust temps. you wont make any more power after 17 psi with the k27 it already cant handle the air flow, notice how power drops so soon on the stock m106 turbo, with a new style turbo and some good charge cooling (either bigger intercooler or liquid to air, or combination with water injection) you can make some serious power, and hold that power longer, goad hold to redline. Ive done the dyno testing, so I have the facts. I think a k27 with all the right stuff could make a peak of close to 400 but will not hold that power for long before it runs out of power.

Dan,

I know you said the K27 could do 400hp and there are plenty of people out there doing just that. Porsche guys have been doing it for years and years - many with A/A intercoolers!! Now what they do to the engines to "help" the K27 get there I don't know, but the fact is that there are K27 boosted units that make 400hp all day long. I've driven Ruf 930's that do it (scary cars) no problem. I searched for 10 seconds on google and found this example just for starters:

http://www.race-cars.com/carsales/porsc ... 2608ss.htm

Now maybe they are using the 7200 K27 (not sure what the differences are) and that is allowing them to get to 20psi - I don't know. I think the 7200 boosts sooner - otherwise I think all K27's have the same thru-put (flow) capabilities. I'm sure they are using BIG cams too.

My goal is to finish putting my Motec ecu and then try to tune on the chassis dyno up to ~20psi. I don't see why I could not get there, or how I would have diminishing returns after 15psi. I will be running a W/A spearco intercooler that is rated to 1000HP.

I think what you are saying is that between 15 and 20 psi you are getting more manifold pressure, but that it cannot get past the intake valves to get into the engine because the valve lift is too limited?? This inturn causes this heat build loop that you are talking about?? That does not really make a lot of sense to me but until I see otherwise I'll take your word for it. Your turbo could not get from 15 to 20 psi if more air isn't flowing to drive up the pressure to 20psi in the first place though; right??

I think on one hand it sounds like you are saying that the K27 does not have the flow capacity to get to and hold 20psi no matter how hard it is driven and on the other hand you are saying that the real reason is not the turbo but the stock M30 setup (cam mainly) that is the reason.

I think the K27 can do 20psi. Can a stock 3.5L M30 make it do it?? I don't know. It sounds like the consensus is that the M30 cannot drive/would greatly struggle to drive a K27 unit to 20psi because of crappy cams. Is that the concensus guys??

Should I even attempt 20psi with a stock cam?? If not I guess I need to start looking for a new cam.


[Edit by Jesse on [TIME]1137729515[/TIME]]


[Edit by Jesse on [TIME]1137805498[/TIME]]

[QUOTE="345is"]Retarding the Ignition timing does infact cause exhaust temps to rise. Put it this way, if you have an inefficient turbo and the compressor side of the turbo is getting out of its range, you are there for creating more backpressure, (between the cylinders and the turbo) higher exhaust temps, more heat in the charging air, ( because of a over worked turbo, if the compressor is at the end of its range because you are running it at high boost levels, you are there for spinning the turbo compresor faster which translates into higher intake temps which translates into higher exhaust temps) , so as u see using a turbo that is near the end of its range of air flow creates unwanted heat in every aspect of your engine setup. your right in saying that a turbo cam would help, but I was talking about a stock M106 with the MILLER air to liquid cooler and MAF Kit and Wastegate. No internal mods. So now with this info, what can you do? raise the boost, why, so you can blow your engine do to unsafe exhaust temps. you wont make any more power after 17 psi with the k27 it already cant handle the air flow, notice how power drops so soon on the stock m106 turbo, with a new style turbo and some good charge cooling (either bigger intercooler or liquid to air, or combination with water injection) you can make some serious power, and hold that power longer, goad hold to redline. Ive done the dyno testing, so I have the facts. I think a k27 with all the right stuff could make a peak of close to 400 but will not hold that power for long before it runs out of power. [/QUOTE]

345is, hey, do you have a name, I feel strange addressing you as a car nomanclature...
,

I had to read your post a few times before I understood what you were saying. I believe you mean that by retarding timing, you can run more boost, thereby increasing compressor outlet temp, this in turn defeats the purpose. That I understand. But Im still right in that given a static boost, retarding timing reduces combustion temps.

I still believe that the M106 with the stock K27 can make 400hp(~350whp) WITH the right engine mods and addon parts. The reason no one has to date is becaust they keep trying to do it with just bolt on stuff. The stock head and low CR just wont let you get there...as you have found out like every other 745i owner. The easiest being to raise the static compression from 8:1 to 9:1. Then 10psi gets you 350whp. The other way is re-build the head, do all the approptiate head work and use a longer duration cam, within reason, like a b33 cam, then your in pretty good shape also.

RussC

Just so you know, You can spend all the money you want on doing head work and and other mechanical internals, that wont do much when your turbo cant support more than say 320 whp. try this put a bigger new style turbo on your m106 and I garantte you that you will be blown away with the power. Oh and by the way if you raise your compression you will not gain hp, you will loose hp. and also retarding the timming to much will indeed raise your exhaust temps!

[QUOTE="345is"]Just so you know, You can spend all the money you want on doing head work and and other mechanical internals, that wont do much when your turbo cant support more than say 320 whp. try this put a bigger new style turbo on your m106 and I garantte you that you will be blown away with the power. Oh and by the way if you raise your compression you will not gain hp, you will loose hp. and also retarding the timming to much will indeed raise your exhaust temps![/QUOTE]

Hu,
Raising compression 1pt will not make the system lose power, it'll only lose power if you don't properly adjust the timing and boost to compensate for it, and use the appropriate fuel quality. Raising compression will increase power output for a given air volume, I beg to differ. Just using the formula here, with explanation:

All motors have a static compression ratio. This is the amount that the air inside the cylinder is compressed. It is a ratio of the cylinder volume at BDC to the volume at TDC. When a supercharger is added, additional air is forced into the cylinder effectively raising the compression ratio. The result of this is called effective compression. The formula for finding the effective compression is very easy: ((boost psi / 14.7) + 1) x motor compression = effective compression.

So, if you agree with that, motor with 15psi and 8:1 compression has an effective CR of:
((15/14.7)+1)x8=16.16
Working the formula to now find psi needed to make the same power with 9:1 CR:
((x/14.7)+1)x9=16.16 gives a new psi of 11.7psi.

The air flow rate does not change for this formula to work, the turbo is putting out less air going from 15psi to 11.7psi. The mixture is compressed further with higher compression, giving a BMEP higher with the same air flow. Andrews E34 with the M30b35 easily make 360whp with 12-13psi and 9.2:1 CR. And that engine isn't way different than the M106. Well, I guess it is a little bit.... But with the stocke M106, your still need the appropriate fuel/ingintion upgrades.

I don't have the CR formulas right in front of me to calculare the torque increase for a given system ie air flow vs CR. But that is a fact, we all know this. Now, heat is increased, so you need to compensate for that, even using the above formula and boost with better ICs, better fuel/ingnition management.

I also disagree with your very first statement, that all the headwork and internal mods won't make a stock M106 make more power. What are you basing that statement on?????? The system with all those mods will make more power as your raising the VE of the engine, this is essensially free power, as it was always there, your just realesing it now to be realized. Like Jesse said, the Porsche guys are getting 400hp crank, now granted the Porsche engines are better at making top end power, so it's a little easier. Bit its still there.

Anyway, theres my take, its still MHO that it's not the k27 thats liming you to 400 crank, its the engine, IC and ECU.

RussC

I geuss we just dissagree, Im just saying that lower compression makes for more hp with a turbo setup, if you are running pump gas. the reason is that you can run more boost and more ignition timming. but, if all your talk was based on race engine fine, your theory is fine. you can run high high octane fuel and then it dont matter how high your compression is.

[QUOTE="345is"]I geuss we just dissagree, Im just saying that lower compression makes for more hp with a turbo setup, if you are running pump gas. the reason is that you can run more boost and more ignition timming. but, if all your talk was based on race engine fine, your theory is fine. you can run high high octane fuel and then it dont matter how high your compression is. [/QUOTE]

None of the stuff Im talking about is specific only to race engines, it applies to all internal combustion engines. Again, Andrews 360whp engine used pump gas. And you can use pump gas on any m30 engine with 9:1 CR and 12psi for 350whp.

Anyway, well see, I look forwared to seeing your stuff in action on Scotties car, paticaurly the MAF with the SMT-6. I guess well get his car on the dyno in near future as get some #s.

RussC

Okay then; WHAT IS THE LIMITING FACTOR ON THESE ENGINES GUYS?? Can anyone tell me? I tend to agree with Russ. I think what Dan Miller is saying on one hand that the VE of these stock engines is not enough to drive the K27 to it's potential and on the other hand he is saying that the M30 does in fact drive it to it's potential and beyond with no gains but actual losses. Which is it?? I highly doubt the latter.

TCD drives these engines over 15 psi routinely with a bone stock setup. Obviously the engine can process the air flow. I've been in TCD's car at 15psi and at 20psi. Huge difference there.

I still don't see why a bone stock M30 can't drive the K27 to 20psi and/or make 400hp. It's all about controls guys. As a controls engineer I know that if I manage the engine properly (heat, ignition, fuel) I can drive the engine to it's mechanical limits.

Dan - What kind of controls platform di you use to do your M30/M106 platform?? Could it log data?? Very curious here.

I guess like Russ says we'll just have to wait and see......

Excuse me while I go tear my stock controls off of my car.........

I would hazzard a guess that the collector on the 745 manifold is significantly smaller than on our manifolds resulting in higher exhaust manifold pressure, restrictive flow to the turbine and greater pumping losses to evacuate the exhaust gasses.

Im not saying the m30 cant drive the turbo to 20 psi, it can, but its way out of its efficiency range at that boost level, there for more heat and and no gain. I dont want to argue about a limit of what the hp avalable to the m106 is. I just know from all the testing i have done that after 16-17 psi its useless, you will only make more unnecisary heat that you wouldnt have from a properly sized turbo for that aplication. that is all im saying.

In some looking for a K27 turbo map, I came across this thread from TJ in Boone. It has a map and some calculations from TJ on the air flow of a 3.0l engine to the map. Couldn't have done it better myself. Thanks TJ. It appears that that map for a k27/2 with a reported .72trim wheel(?) will make 400hp at 22psi pretty easy and still be on a 70% efficency island. Just interesting and relavent to this converstion.

K27 compressor map

RussC

[QUOTE="345is"]Im not saying the m30 cant drive the turbo to 20 psi, it can, but its way out of its efficiency range at that boost level, there for more heat and and no gain. I dont want to argue about a limit of what the hp avalable to the m106 is. I just know from all the testing i have done that after 16-17 psi its useless, you will only make more unnecisary heat that you wouldnt have from a properly sized turbo for that aplication. that is all im saying.[/QUOTE]

Dan,

I think you are making some assumptions about your setup that may not be valid. Is your exhaust system up to the task? Is your tuning up to par? Is your intercooler efficient? All these things need to be excellent to produce the desired results.

I believe the k27 may not be the reason for your low HP numbers.

Whatever the case, I don't think you are in a position to unilaterally declare that the k27 will not produce a certain output.

You are however in a position to say that your setup, on your car, on a certain day, on a certain dyno made 270rwhp at 15psi.

Todd



[Edit by TCD on [TIME]1137850542[/TIME]]

[QUOTE="345is"]Im not saying the m30 cant drive the turbo to 20 psi, it can, but its way out of its efficiency range at that boost level, there for more heat and and no gain. I dont want to argue about a limit of what the hp avalable to the m106 is. I just know from all the testing i have done that after 16-17 psi its useless, you will only make more unnecisary heat that you wouldnt have from a properly sized turbo for that aplication. that is all im saying.[/QUOTE]

is this statement blanketed over the motor with any turbo or just the k27? b/c once i get to the pistons and cams i want to push 20ish psi with this turbo and maybe more depending on the gains over 20 psi. maybe more with a slightly larger turbo. i think how much boost an engine can run and make use of has to do a lot with your setup. for instance, card counter (on bfc aqnd a friend of mine) has a bone stock internal (except for headgasket) 2.8 motor and runs 30 psi boost on it. the turbo i believe is rated for a max of 27 psi. he makes 635 rwhp. also, andreas in sweden makes 35 psi boost on a m52 motor with stock parts from other bmw motors in his motor. neither car have blown their motors.....yet. so i think it is all in the efficiency of your setup.

Hello Todd, do you think you could do a run with that 745i you have at 20 psi? Please. I am done arguing, let move on, if I am wrong about the turbo being limited, fine, but at least will you prove it on the dyno? that would be great. an why has no one done it? why is no one running the k27 at 20 psi? anyway, let me know if you run it, Im not dissagreeing with the dyno you did at 15 psi wth the 745i I just want to see it run at 20 psi, and see the hp #s compared to 15psi.

[QUOTE="345is"]Hello Todd, do you think you could do a run with that 745i you have at 20 psi? Please. I am done arguing, let move on, if I am wrong about the turbo being limited, fine, but at least will you prove it on the dyno? that would be great. an why has no one done it? why is no one running the k27 at 20 psi? anyway, let me know if you run it, Im not dissagreeing with the dyno you did at 15 psi wth the 745i I just want to see it run at 20 psi, and see the hp #s compared to 15psi.[/QUOTE]

My 745i had a TCD turbo kit on it.

Very few people run 20psi on a 745i for several reasons.

1. The fuel system is difficult and expensive to upgrade.
2. The ignition timing is dificult and expensive to modify effectively.
3. The stock headgasket is unreliable at 20psi.
4. The stock 745i intercooler is inadequate for such HP levels.
5. The exhaust system is also inadequate for such HP levels.
6. Most 745i are old junk in a sad state of disrepair.
7. e23s are old, big and some may say ugly

That said there are several beautiful 745i running 17-20psi. I have never seen a dyno sheet for one though. I do have a customer with a 745i setup in an e24. He is installing ARP studs and a MLS next week. The car is already equipped with MSII and he has run 20psi previously. I have no idea if he'll be putting it on the dyno.

Todd

what did that 745i that you dyno`d make for power? I didnt see a dyno sheet there.

[QUOTE="345is"]what did that 745i that you dyno`d make for power? I didnt see a dyno sheet there.[/QUOTE]

3.2L
ported cyl head but otherwise stock
14.5psi
68F
331rwhp/316rwtq

I Made 330 rwtq at 3100 rpm with stock turbo, but only 270 rwhp at 4700 rpm. with New turbo Im making all the power up top. Torque has moved up and hp has moved up. Dyno sheet will now look more like todds set up , he makes max torque at 4500 and max power around 6000 rpm. doesnt that tell you that the k27 is running out of air flow volume? I dont want to hear any more asumtions about the k27, I have a Bigger turbo now and I have moved the power curve up in the rpm range, and now Im making power to the redline. the stock k27 willnot make power all the way to the redline. Look at any dyno sheets for a 745i the power drops severely at 5000 rpm. now look at basicly the same engine, Todds M30 turbo, what does his dyno look like? Power all the way to the redline. the difference is in the turbo.


[Edit by 345is on [TIME]1137894579[/TIME]]

[QUOTE="345is"]I Made 330 rwt with stock turbo, but only 270 wtq.[/QUOTE]

What effect does gearing have on the HP vs. TQ spread?? For example would you get a higher TQ number but lower HP number if you ran a 3.73 vs. a 2.93??

[QUOTE="Jesse "]What effect does gearing have on the HP vs. TQ spread?? For example would you get a higher TQ number but lower HP number if you ran a 3.73 vs. a 2.93??[/QUOTE]

It should not have any.

Okay, so basically what I am reading here is what I suspected/knew in the first place and that is given good controls and good heat management (big IC's), there is no reason that a stock 8.5:1 M30 3.5L engine running a K27 could not see AND use 20psi and/or 400chp+.

My thought in general is would the German engineers have under cut the turbo application?? A stock Porsche 930 for example came with a K26!!! A K27 is a big upgrade for them and what they use to make the big numbers. Now the guys that make big BIG numbers(900-1000HP) switch over to Garrett of course but that is in an entire differert league all together.

with New turbo Im making all the power up top. Torque has moved up and hp has moved up. Dyno sheet will now look more like todds set up , he makes max torque at 4500 and max power around 6000 rpm. doesnt that tell you that the k27 is running out of air flow volume? I dont want to hear any more asumtions about the k27, I have a Bigger turbo now and I have moved the power curve up in the rpm range, and now Im making power to the redline. the stock k27 willnot make power all the way to the redline. Look at any dyno sheets for a 745i the power drops severely at 5000 rpm. now look at basicly the same engine, Todds M30 turbo, what does his dyno look like? Power all the way to the redline. the difference is in the turbo.

[QUOTE="345is"]with New turbo Im making all the power up top. Torque has moved up and hp has moved up. Dyno sheet will now look more like todds set up , he makes max torque at 4500 and max power around 6000 rpm. doesnt that tell you that the k27 is running out of air flow volume? I dont want to hear any more asumtions about the k27, I have a Bigger turbo now and I have moved the power curve up in the rpm range, and now Im making power to the redline. the stock k27 willnot make power all the way to the redline. Look at any dyno sheets for a 745i the power drops severely at 5000 rpm. now look at basicly the same engine, Todds M30 turbo, what does his dyno look like? Power all the way to the redline. the difference is in the turbo. [/QUOTE]

3.2L with 270 cam makes totally different power than a 3.4L with a 260 cam.

What are the specs of the current turbo?


[Edit by TCD on [TIME]1137895856[/TIME]]

264 cam in M106. turbo Cold side .50 a/r Hot side .83 a/r

[QUOTE="345is"]264 cam in M106. turbo Cold side .50 a/r Hot side .83 a/r[/QUOTE]

So what are the specs of the compressor and turbine? T3 with a .83 a/r on a 3.4L should spool like, immediately!

Is this a Chinese Garrett copy sold by SS Autochrome?

Dan - What controls system are you running????? What rear end gear are you running???