MyE28.com DEV

So I got asked, "give me a number."

Probably around 3589 cc or a bit less.

Consider:
Two generally available cranks: the 86 mm stock one for the M30, or possibly the 90 mm S38B38 crank. As I understand it, these are very close to becoming NLA.
Bore sizing. The stock M30 is 92 mm. Given the issues with BMEP, leaving as much cylinder wall thickness as possible makes a lot of sense. Do some minimal bore cleanup, e.g., first-over on rings and you''ll probably be OK, provided you don't do something stupid on boost levels. Push boost beyond, say, 1,2 bar (18 psi) and all kinds of nasty engineering issues come to the fore.
As it is, 18 psi means a lot of things need to be done throughout the motor. Fine, I guess, if you are looking for someplace to hide the drug proceeds. I would stay in the .8 to 1,0 bar (12 to 15 psi) range.
Done properly, with all the needed ancillary stuff, this will get you to ~500 fwhp and not have the motor eat itself on a weekly basis.
And 500 fwhp will be sufficient to allow you to stain your shorts. Trust me.

4 digit RWHP numbers possible on an m30 for less than $15K in the engine (not ancillaries)?

thespeedfactory wrote:4 digit RWHP numbers possible on an m30 for less than $15K in the engine (not ancillaries)?

If you think so, you are putting something in your body that is not good for you.
Pull your head out of your ass.

Just a question.

<-- Head still in ass

^ ^ ^ This. v v v

http://www.ebaumsworld.com/pictures/view/58073/

What happens at 18psi?

Shadow wrote:What happens at 18psi?

I bugger your wife.
Around that boost level a lot of internal strains on the engine begin to show up. Not necessarily immediate failures, but component life expectancies start to drop off rapidly--HG, components subjected to exhaust gases (heat), reciprocating components. Typically BMEP numbers begin to rise rapidly as well. Octane requirements are well beyond anything you can buy at the pump. Think 114+.
For historical comparisons, during the 80s, BMW built some 1.5 liter 4-bangers for F1. These ran boost at anywhere from 3 to 4 bar( 45-60 psi). These . . .confections . . . burned something that was a known carcinogen to reduce (not eliminate) detonation. They were dynoed at around 1350 hp. That number was used because that was all the BMW factory dyno could support. These things, used for qualifying, had a life expectancy of about 20 minutes.Think a chainsaw on meth.

Another tidbit. In the mid-80s, while BMW was doing the 745/M106, Dinan was doodling with their turbo'ed M30. These ran around 12 psi max boost. With a NA M30 on an engine dyno and run on a computer-controlled loop which simulated a hot (for the time) lap on the Nurburgring. The engines lasted about 160,000 miles equivalent before significant wear caused the tests to be stopped.
For comparison, the T04-turboed Dinan M30s were put through the same cycle. These engines began to give up the ghost at around 40,000 miles. Stock M30 = ~200 hp. Dinan Turbo = ~460 hp +/-. Double the power in exchange for 1/4 the life expectancy.

If you have the resources to do engine rebuilds on alternate weekends, be my guest on major boost. But staying around 15 psi seems to be a reasonable compromise.

Good advice. Thanks for the explanation, Ken.

I have a PB built bottom end (8.8 forged pistons, total seal rings and a good amount of PBurke magic). I plan to run 15psi day-to-day running MS2 and water/meth and a FMIC. Paul was pretty adamant about the 15psi threshold. Will be interesting to see how long I can go before being tempted to dial it up.

cvillebimmer wrote:Good advice. Thanks for the explanation, Ken.

I have a PB built bottom end (8.8 forged pistons, total seal rings and a good amount of PBurke magic). I plan to run 15psi day-to-day running MS2 and water/meth and a FMIC. Paul was pretty adamant about the 15psi threshold. Will be interesting to see how long I can go before being tempted to dial it up.

You're welcome. By "dial it up," I presume this means you will pay attention to PB's advice, right?

nice info

Ken H. wrote:

cvillebimmer wrote:Good advice. Thanks for the explanation, Ken.

I have a PB built bottom end (8.8 forged pistons, total seal rings and a good amount of PBurke magic). I plan to run 15psi day-to-day running MS2 and water/meth and a FMIC. Paul was pretty adamant about the 15psi threshold. Will be interesting to see how long I can go before being tempted to dial it up.

You're welcome. By "dial it up," I presume this means you will pay attention to PB's advice, right?

You and Paul are on the same page at the 15psi threshold. If I go beyond that and it goes kapow, it will be a good excuse to have Paul work his magiic on the head, which is a stock refresh.

cvillebimmer wrote: You and Paul are on the same page at the 15psi threshold. If I go beyond that and it goes kapow, it will be a good excuse to have Paul work his magiic on the head, which is a stock refresh.

"If you have the resources to do engine rebuilds on alternate weekends, be my guest on major boost. But staying around 15 psi seems to be a reasonable compromise."

Ken H. wrote:

cvillebimmer wrote: You and Paul are on the same page at the 15psi threshold. If I go beyond that and it goes kapow, it will be a good excuse to have Paul work his magiic on the head, which is a stock refresh.

"If you have the resources to do engine rebuilds on alternate weekends, be my guest on major boost. But staying around 15 psi seems to be a reasonable compromise."

I wish I had unlimited resources, then I would have had Paul build the head at the same time he built my block. I regret not doing that now. 12-15psi is the plan for 99% of the time. Will a trip to 18 grenade the engine? Maybe, but most likely it will be a popped HG or lifted head that precipitates head removal. Its a risk I'd be willing to take. If the head ever has to come off, it will be rebuilt correctly.

As far as making forays into 18 psi goes, you might want to consider a couple of things.

1.If the HG does let go, the head bolts or studs probably got stretched as well. Is the Cheap Thrill really worth the aggravation of having to rebuild or replace the head?

2. Pull out the compressor map for the turbo now on your motor. Look over on the left side (Y-axis) and find the appropriate Pressure Ratio. Assuming you're at sea level, that niumber is going to be around 2.22, not accounting for any lowered intake pressure coming from the air cleaner--typically around .5 psi or so. (18+14.7) / (14.7-.5) = 2.30 Pr.

Using one of the good turbo modeling programs, input the known values for variables related to your motor. One of these will be Manifold Pressure. See what you get at, say, 10-12-15 psi in terms of air mass delivery, shown in pounds.
Transfer those number to the X-axis on the compressor map.

Now see where the points lie on the compressor efficiency islands.

Do this again for 18 psi/2.30 Pr. In all liklihood, the 18 psi/2.30 Pr will be WAY over to the right, pushing into choke.

This means the air mass coming out of the compressor and into the intake plenum is going into stall and the temperatures are beginning to skyrocket.
This is not a recipe for increased HP or engine longevity.
So "just a leetle bit of 18"?
Paul didn't tell you 15 psi because he had nothing better to do.

One thing Paul explained to me, and makes perfect sense, is that more boost does not always equal more power. Boost is just the measure of resistance to air flow through your engine.

M. Holtmeier wrote:One thing Paul explained to me, and makes perfect sense, is that more boost does not always equal more power. Boost is just the measure of resistance to air flow through your engine.

True, dat.
What builds power is air mass moved through the motor. An IC engine is an air pump, nothing more. Complicated, yes, but just a pump.
Move more air and you get more power. This is why a larger compressor working at a lower boost can deliver more power than a small turbo cranked within an inch of it's life.

This takes into consideration heat gained from compression of the air (why we have ICs) and the inertia of moving a larger physical air mass (turbo lag).

This basic lesson in physics gets lost on the liceboiz in the amphetamine-fueled rice grinders. "MY turbo puts out 40 psi !!
"So why aren't you running in the AA Fuel Funny Car bracket, hmmmm?"

When I made the trip past 15 psi in 2008 or so I simply dialed back the timing, dialed up the boost and listened for ping with a HKS monitor. If I got a little ping, I increased the meth by a bit.

I was perfectly happy running on the ragged edge of timing. I ran 12-15 psi on stock timing for 2 months, just for giggles before exhaust temps got the best of me.

I agree with Ken completely. When I ran 15 psi with a split second piggy back, it was a sweet spot for the engine. I drove the car all the time. Once I went to Haltech, full sequential, HX55, 20+ psi, I was fixing the car more than I was driving it.

Ken H. wrote:Another tidbit. In the mid-80s, while BMW was doing the 745/M106, Dinan was doodling with their turbo'ed M30. These ran around 12 psi max boost. With a NA M30 on an engine dyno and run on a computer-controlled loop which simulated a hot (for the time) lap on the Nurburgring. The engines lasted about 160,000 miles equivalent before significant wear caused the tests to be stopped.
For comparison, the T04-turboed Dinan M30s were put through the same cycle. These engines began to give up the ghost at around 40,000 miles. Stock M30 = ~200 hp. Dinan Turbo = ~460 hp +/-. Double the power in exchange for 1/4 the life expectancy.

Dinan's testing isn't really representative of the kind of duty the average street driven turbo car sees. I've never worn out a set of rings or bearings. I might spend 3-5% of the time under boost, usually for less than five or ten seconds a pull. The old 2.7 was together for almost two years at 1.4 bar. It loooked great when it came apart. The only issue was broken ring lands, which were the result of severe detonation due to a lean condition at about 16 psi.

Especially with 1 bar or less, I really don't think boost will factor into engine life. High boost slightly increases the odds of a catastrophic failure but its still nothing to worry about. All you can expect to blow on these motors is the head gasket, and thats avoidable with care and self control.

Dan, what you say is true w/r/t to the usage profile. But a few things to consider.

The engine dyno loop, simulating the Nordschleife, was designed to stress the engine heavily. As I understood it, coming from Dinan's technicians, it was never meant to be a go-to-the grocery usage pattern. It was originally written to be a "98th percentile" user model, designed to see what would happen over 200,000+ km of very hard use, not to say abuse.

The engine on the dyno was shut down at mileage-specified intervals for routine maintenance--oil changes, valve adjustments, coolant flush and so on. ISTR that Declan Doyle, Dinan's head engineer, said a water pump had to be replaced, as did alternator brushes. I think the bottom end was still in good shape at the end of the test. Wear was showing up on rings and top end. In other words, due for a valve grind and possibly first over on rings. Not unexpected after the equivalent of more than 11,500 laps on the Nordschleife running hard all the way. To be noted, this test took something very close to 2,000 Hobbs time hours to complete. 80+ days of time on the dyno. You can do this when you have a major auto manufacturer's resources available.

So some very competent people were able to obtain a solid baseline for what would happen with a NA M30 being driven close to its design envelope for an extended period or distance.
Putting the Dinan M30 turbo through the same profile allowed for an apples-to-apples comparison where said turbo motor was having the snot wound out of it. I agree with your points about the amount of time nearly all turbo'ed cars spend under boost. But the dyno runs weren't meant to simulate drag usage. The idea here was to see what would happen if the engine was run hard for extended periods. So in that sense, a valid comparison to the NA engine's usage pattern.

The IC on Dinan's turbos wasnt terribly big, and the technology of the time --1985 or thereabouts--had the T04 as The Hot Setup. We have come a long way in 25-plus years as far as technology and engineering are concerned.

When DE put their turbos on the market, they offered a 36,000 mile parts and labor warranty. This mirrored what BMWNA was offering on the new cars. Dinan's relationship with BMWAG and NA has always been a tad...different. Operating as an indie, the parent can offer "plausible denial" on just about everything. OTOH, DE got and gets a LOT of engineering support from the parent. So someone thought they would be OK with a 36K warranty.

What began to develop after a couple of years was that the DE turboed cars were beginning to show up with various problems. Mileage and time, still under warranty. Fixed, mostly on DE's dime. This had less-than-satisfactory effects on the bottom line and a lot of effort on the Service Dept's part to keep customers happy.

At this point, the "turbo" dyno runs were done. This not so much to do sophisticated tuning and obtain power numbers (which ad been done during development), but to determine just what was not holding up and why.

Net-net, DE Corporate phased out their turbo offering.

But the results, that the greater heat stress and loadings on the motor coming from the gas volume moved by FI shorten its life expectancy, I believe are valid.

Source on my story: I had an extended conversation with Declan and Jeff Hecox regarding converting my 735 to FI, this around 1986-87. The problems noted above were beginning to crop up and Declan was a bit reluctant to hand me a problem.

WTF with this don't go above 15psi shit. 20+psi here continuous abuse on a stock engine with no issues.

Good & Tight wrote:WTF with this don't go above 15psi shit. 20+psi here continuous abuse on a stock engine with no issues.

Otis, what do you find to be an acceptable BMEP? Why?

Good & Tight wrote:WTF with this don't go above 15psi shit. 20+psi here continuous abuse on a stock engine with no issues.

Are you using the MAPdaddy MAP sensor?

Ken H. wrote:

Good & Tight wrote:WTF with this don't go above 15psi shit. 20+psi here continuous abuse on a stock engine with no issues.

Otis, what do you find to be an acceptable BMEP? Why?

Ken, I'm not a math person, just someone who tinkers.
BMEP is not a discussion I can engage in.

This was a very good read.
Just about a week too late, although I've been told to chill on the boost before......
BUT...
Boost is the car guy's crack, and I'm a junky.
There, I said it...

Good & Tight wrote:

Ken H. wrote:

Good & Tight wrote:WTF with this don't go above 15psi shit. 20+psi here continuous abuse on a stock engine with no issues.

Otis, what do you find to be an acceptable BMEP? Why?

Ken, I'm not a math person, just someone who tinkers.
BMEP is not a discussion I can engage in.

So you build engines and components thereof by throwing them together to see if they work?

Otis, I'm not dissing your workmanship (which from what I hear is pretty good) but having a solid grasp of the physics and engineering fundamentals behind what you're doing and why would move things a pretty good ways down the road. Sorry about the pun . . .

As to "continuous abuse": How many cumulative engine hours has your build seen running at 20+psi? Not just running it up to 1.4 bar for periods measured in seconds, but holding 1.4 bar for, say, a couple of hours at a time. And yes, you can do this; just run it in a lower gear and crank the snot out of it. I can provide the locations of any number of roads where this can be done.

FWIW, the wear factors for both heat stress (FI) and RPM is cumulative.
For example, I have seen data that indicates if an M30 motor is run at 8000+ rpm such as might be experienced in a road race application, it might be good for 4 hours or ~300 miles.
Bump that up to 9000 rpm as seen in a drag racing application and that number might drop to under an hour---maybe covering less than 75 total miles. The rate of wear is shown to be exponential in nature---a 20% increase in average revs, say from 4500 to 5400+/-, can increase wear by more than 5-fold.

As an example, what kind of engine life do the factories expect to see from a Formula 1 motor that may crank at 13K-plus?

What's worth noting with this analysis is the wear, in effect, takes engine life "out of the bank." Do a couple of hours of track time interspersed with a lot of hard street driving and engine life will be commensurately reduced. Hard street driving, where revs = ~4500-5000 on the average, you might get 500 engine hours or around 30,000 miles. But the higher revs and higher loadings "deplete" the engine's life more quickly. So that usage pattern might yield only 15,000 miles before it's rebuild time.

Similar conditions apply w/r/t increased boost. In effect, running at 1 bar, you are making a 7-liter engine out of a 3.5 liter one. Burning air-fuel mixtures creates heat, and heat creates stress. Basic thermodynamics. There is no free lunch.

You may wish to dismiss the controlled engine dyno tests that BMWAG and Dinan did 25-odd years ago, but I tend to put a lot of credence into that kind of research. I have this bias towards respect for math and engineering majors.

The 1 bar(15 psi) number isn't carved into stone; rather it seems to be a workable compromise between increased power and desired engine longevity. If balls-to-the wall raw power is the goal, then be my guest. But somehow I don't think most people who go to the effort of tweaking their motor get their nut by spending their coin and time doing repetitive rebuilds.

Ken,

You prefer to spend an enormous amount of time researching and calculating prior to putting a plan into action.

Some people prefer to learn through experimentation.

Some people use HP as goal, some reliability and all some sort of combination of both.

Since it's a hobby for all, any combination of the above should be acceptable to everyone.

Todd

T_C_D wrote:Ken,

You prefer to spend an enormous amount of time researching and calculating prior to putting a plan into action. Some people prefer to learn through experimentation. Some people use HP as goal, some reliability and all some sort of combination of both. Since it's a hobby for all, any combination of the above should be acceptable to everyone.

Todd

All true. But I have spent Christ Knows how much time, money and tears doing or being led through experiments. Once I paid attention to what I was being told by people whose business was doing it properly the first time, and those who are Professors of Engineering, I began to get something pounded through my thick Scotch-Irish skull.
Understanding how and why certain steps are taken and what has shown to work seems to avoid reinventing fire, let alone the wheel. I don't have a whole lot of use for "Fire, Ready, Aim."

OK, someone had to do the experimentation, but why not move forward from there?

Todd, my comments are not directed towards saying "Big HP = Dumb." Nor am I saying that if a given build can't get 300,000 miles, obviously something is wrong.

My objective in all the lecturing is to lay out some elements for consideration which will give a prospective builder--newbie or experienced--some benchmarks to help them get where they want to go with less misspent time and other resources.

I do things the same way. While it would be desireable to understand an engine build to the extent that you do, its not necessary to achieve very good results. I lack the money, time and energy to work on your level. Luckily I've enjoyed stumbling my way through my build with only a rudimentary understanding of the concepts involved. I'm also satisfied with my results.

One thing I do know is that one of the main detriments to engine life is high RPM. I substitute a great deal of understanding on my part for a great deal of faith in the motor BMW put together for me. I believe that keeping RPM within the realm that the engine was designed to run goes a very long way in maximizing reliability and engine life. In my case, I compare my M20B27 to the M54B30. I'm running an 81mm stroke up to 7000 RPM. The later 3.0 motor uses an 89.6mm stroke up to the same engine speed, and does so from the factory bone stock. The S54B32 runs a 91mm stroke up to 8000 RPM, bone stock, on approximately the same amount of bearing surface area as all the other small block six cylinder motors. Of course theres more to it than that, but I feel comfortable enough with the relatively short stroke and moderate max RPM to put my mind at ease. I won't be getting every last drop out of the motor with this methodology, but on my budget its not a bad way to work.

I don't know what it is about high boost that seems to diminish ring life. I've read that its a common issue. I have not seen it in my motors over the years but I probably only have 30 or 40 thousand miles on the road with a turbo under the hood. It seems manageable. You won't be re-ringing on an annual basis, and if you are there is certainly another issue.

Considering outputs in excess of 150hp/liter I keep expectations realistic. I would definitely hesitate to run wide open at full boost for ten miles down the highway. I don't even like winding out fourth gear. I have most of my fun in 1-3 with an occasional pull into 4th. My motor is not idiot proof, not by a longshot. It is solid enough to reliably manage what I use it for. I know what it can handle and I know what constitutes pushing my luck. Thats good enough for me.

So as long as it's under 18psi no matter the power level,
it's ok? It's the psi that damages the engine, not the power?

Just trying to get that straight.

Incorrect, boost is just one variable. Boost doesn't damage an engine either. Detonation, heat and physical stress damage engines. There is no magic number, though the lower your boost level is the safer you are. Some guys ruin engines at 8 psi, others have no problems at 20+.