Normally Aspirated Modifications to M5s?

[klrskies]

Not inquireing about Forced Induction, who has modified their M5 engines for performance gains and what did you do?

[Randomg]

I did a search for "dyno", it took me 5 seconds, and it came up with almost every topic that has to do with increasing the power of the s38, cam gear, b36 cams, chips, maf, high compression pistons, engine management, headers.

Do a search.

[Jeremy]

You want bolt ons I would assume? There isn't much.

[klrskies]

No, not necessarily..but intrested in bolt ons too.

[Cory]

My old one had a Fahey Cam Gear and Conforti Software. My new one has a Dinan Cam Gear and Software. Not to hijack your thread, but I'm a big fan of keeping everything stock and 100%+ sorted out/mainained to extreme levels of perfection.

[klrskies]

My old one had a Fahey Cam Gear and Conforti Software. My new one has a Dinan Cam Gear and Software. Not to hijack your thread, but I'm a big fan of keeping everything stock and 100%+ sorted out/mainained to extreme levels of perfection.

That's cool too.

[RoyW]

Bolt on an S38b36 (or better yet an S38b38) engine... that should do it!!

Add euro headers, a chip, lightweight flywheel, and bigger cams and you'll be pretty much maxed out!!


-RoyW

[klrskies]

I'm thinking something's not so good with a 4 valve engine making 73 HP / Liter and peaking @ 5500 rpm. The intake tract, other than not being tuned length & perhaps having some top end restriction with the AFM system, should be pretty good since its the same one that supported the euro engine. Perhaps it's a combination of issues...the exhaust sides' lack of tuning & restriction @ high rpm, the lack of adequate cam overlap to promote cylinder filling and offer assistance to the intake sides cylinder filling capability that are perhaps suspect.

regards,
Ken

[Jeremy]

They're not the same head, but they are similar.

The US motor makes less power due to cam selection, less static compression, and slightly less aggressive tuning. The US motor was also slightly under-rated. Most examples make more than their rated 255 hp, and/or pick up really healthy gains with aftermarket tuning.

Jeremy

[klrskies]

I'll bet the engineers at Motorsport were scowling and grumbling, and wondeing what the hell was going on when they were directed to de-tune the the engine for the U.S. market...Not exactly what that division was geared up for! Oh well, it is what it is once the politics were set.
regards,
Ken

[Jeremy]

I'll bet the engineers at Motorsport were scowling and grumbling, and wondeing what the hell was going on when they were directed to de-tune the the engine for the U.S. market...Not exactly what that division was geared up for! Oh well, it is what it is once the politics were set.
regards,
Ken

The M88/3 is de-tuned race motor to start with, I don't imagine there was much grumbling. BMW engineers are used to working within constraints. It's just that the constraints for the US market (dictated mainly by the smog/CARB assholes in California) were stricter than what they had in place in Europe.

Jeremy

[Randomg]

The fact that a chip can give this car 15-20 rwhp to me says BMW was a little lazy in the US conversion.

[Jeremy]

The fact that a chip can give this car 15-20 rwhp to me says BMW was a little lazy in the US conversion.

Keep in mind that BMW's tune had to run on 91 octane Cali-gas without knock. Most areas had/have at least 93 octane available. It wasn't a "lazy" tune IMHO, they just had to play conservative to prevent problems and had to leave some potential on the table as a result. The rest of the country doesn't have to worry about this as much since we have better gas available. Up until a few years ago I could still get Sunoco 94 at the pump.

Jeremy

[klrskies]

The fact that a chip can give this car 15-20 rwhp to me says BMW was a little lazy in the US conversion.

Yeah, Not much "race engine" left in it by the time the changes were in place. Still, it's a pretty good little engine, even today.
The US market was late and small, so probably no extensive program from BMW to find ways of regaining performance either with the constraints placed upon them. The next generation provided the opportunity for that.
regards,
Ken

[Randomg]

It's still a racey in that it trades low end torque for hp, it makes 80 hp/l with a chip (according to my dyno sheet at least) which was not common at the time, it screams like one, and it gets bad gas mileage.

[klrskies]

Lol ...yes, I suppose it is a racer in that respect. seems more confused than anything.

[Matt]

So the summary is, you can start by converting it back to euro-ish specifications.

- real headers
- raise compression
- better cams
- no catalyst
- new software

of course, in doing this you will want the Fahey crank hub.

On the issue of cams you can go better than the factory.

This is all with BMW factory parts [or with JE pistons, Schrick cams, and Conforti or other US software, which are as-good or better than factory parts..]

I'd wager that the next step would be to ditch the AFM system, and possibly motronic. The Split Second MAF conversion was popular a while back and and seemed to make power and drivability gains. I would guess that removing the AFM and going to a modern standalone would show even better benefits.

For all its faults, the US M5 with stock Motronic was incredibly docile, reliable, and daily-driver friendly for what that motor started out as and what it did, even in de-tuned form. The Motronic ECU has a few known failure modes and you can usualy find a guy to diagnose and fix one for _Free_ at this point. You cannot build a megasquirt brain for less than it costs to repair any possible motronic problem.

Dinan was building some NA 400hp S38s, which were stroked to 3.9 and had who-knows what else did to them

[paul burke]

Not inquireing about Forced Induction, who has modified their M5 engines for performance gains and what did you do?

I will build you virtually any performance engine component you desire from tool steel billet camshafts to ecu upgrades, want a streetable 400 flywheel HP just inquire. [email protected]


Paul

[klrskies]

So the summary is, you can start by converting it back to euro-ish specifications.

- real headers

I'm fascinated with N/A tuned intakes and exhausts, so yeah, thats possible, as is intake modifications..

- raise compression

I don't know, there isn't alot more head room with compression and the highest octane at the local pump here is 92...more cam overlap would help make it possible though.

- better cams

Or try decreaseing the lobe seperation angle on the existing cams to bump up overlap...required for tuned intake and exhaust to be of additional value.

- no catalyst

yes, were a non-inspection area.
- new software

I'd like to try Millers' emulator set up, or Moates "Ostrich" and Tuner Pro R/T but requires an .xdf editor configuration file first...no one is working on it that I know of.

of course, in doing this you will want the Fahey crank hub.

I'm a toolmaker/designer and have a small machine shop at home and sometimes enjoy making my own parts for fun.

On the issue of cams you can go better than the factory.

This is all with BMW factory parts [or with JE pistons, Schrick cams, and Conforti or other US software, which are as-good or better than factory parts..]

I'd wager that the next step would be to ditch the AFM system,

I built a manomometer for testing, so I may see how much resistance the AFM has at high rpm..understanding it (restriction) would certainly get worse as the engines' breathing improved at high rpm.

and possibly motronic. The Split Second MAF conversion was popular a while back and and seemed to make power and drivability gains. I would guess that removing the AFM and going to a modern standalone would show even better benefits.

I like VEMS features, but have no experience with it...would be intresting. Or the Miller Emulator Chip and MAF conversion.

For all its faults, the US M5 with stock Motronic was incredibly docile, reliable, and daily-driver friendly for what that motor started out as and what it did, even in de-tuned form. The Motronic ECU has a few known failure modes and you can usualy find a guy to diagnose and fix one for _Free_ at this point. You cannot build a megasquirt brain for less than it costs to repair any possible motronic problem.

Agreed. I've poked fun at it a bit, mostly because I expected more from it, but it's pretty good for what it's been thru.

Dinan was building some NA 400hp S38s, which were stroked to 3.9 and had who-knows what else did to them

I think a N/A 300~325 H.P. engine would bring the car up to a good level, and satisfying to me. It could tolerate more cam timeing...it makes adequate torque to pull well at low to moderate rpm in the light e28 chassis with it's stock diff. I like simplier, mechanical engines (yes, I like side drafts too), so I probably wouldn't go forced induction...but one never knows.

I like the e28 chassis...feels like a mature, roomier e30. I don't look at it as a prtected, museum piece. I like driving it alot. I won't mind doing some modifications. I'm naturally curious about what constraints the engine has so I'll search and test a bit...all part of playing with cars.


regards,
Ken

[mooseheadm5]

The E34 M5 had higher compression, hotter cams, and proper headers. It was rated at 310hp at the crank and ran on pump gas.
There is a discussion on cams and gears in this section that you should look up. Lots of good info.

[Rich Euro M5]

Ken,

This BMW Tech Paper explains the differences between the S38B35 and the S38B36 engine.

This Dinan marketing info provides some data (YMMV) regarding the Dinan cam gear. This cam gear is nothing more than the S14 Evo gear.

You should join the Yahoo S38 - M88 Group, if you haven't done so already. There's a huge brain trust of information regarding these engines there.

HTH

Rich

[klrskies]

Thanks for the information Rich, and everyone else who offered guidance. I looked briefly at the S38B36 sheets. Hey, the power adding design brought back power nicely... although I wish Motorsport would have been able to take steps to optomize our S38B35 engines! But then I wouldn't get to play with this one would I? It's all good. I enjoy the ride.

If someone gave me a yugo engine and said " I wonder what could be done to make it perform better" I'd be intrigued for a while with that thought. Not saying this is a YUGO by any means! Many BMW engines seem to be a robust platforms to expand upon A worthy platform indeed.

Anyone know why vanos wasn't applied to the later S38 engines? In a way I'd be glad it wasn't, due to the added complexity, but in the european race for "fastest sedan/saloon" seems it would have been quite an asset.

regards,
Ken

[scottiesharpe]

Not inquireing about Forced Induction, who has modified their M5 engines for performance gains and what did you do?

I'm running a Miller mass air meter, WAR chip and a Perfect Power SMT6. Ignition is a Mallory 6a.

Just curious....Am I the only one here running this setup?

The rest of the engine is stock (M88/3). Open loop--although this summer I may utilize the SMT6 02 sensor input to attempt to get a closed loop system running. Stock factory Cat. B&B cat back exhaust.

The biggest improvement in power was achieved by using better fuel and adjusting the timing map.

[George]

Anyone know why vanos wasn't applied to the later S38 engines? In a way I'd be glad it wasn't, due to the added complexity, but in the european race for "fastest sedan/saloon" seems it would have been quite an asset.

regards,
Ken

Have you ever performed a Vanos repair on an Mx/Sx engine? Its not something you can just bolt onto the head. It would have required a re-design of the s38 head. Not something BMW was going to bother with on a engine that was being phased out. By the time Vanos was available on the M50 the s38 was just about done in the US.

Look at the NV M50 head compared to the Vanos M50 heads. Not a whole lot crosses over.

I'm currently rebuilding an S38b36 for forced induction . I'm enjoying the performance discussion.

[klrskies]

The Miller system looks attractive to me, allowing tuning changes as the engine requirements change. With cams changed,possibly headers and a good tune the engine should be noticeably improved. The small compression change doesn't seem worth the price of pistons.

[T_C_D]

I'm running a Miller mass air meter, WAR chip and a Perfect Power SMT6.

Why are you using a piggyback with the WAR chip?

[gabo1]

Hi Ken!
Miss that car!
Can you post a picture for everybody to see that toy.

Chuck