Performance Mods to stock CSI - Most bang for the buck.

[tripower]

If my CSI came from the factory with 200 HP, I think bumping that up to 240 or 250 HP is doable,reasonable, and cost effective.

1. CAI intake (5-7 HP)
2. high flow exhaust (10 HP)
3. Hot cam (15 HP)
4. Port and polish head (10 HP)

Also there are plenty of areas to drop weight using fiberglass components and replacing some glass with lexan giving me an effective HP increase.

 

[x_atlas0]

Ah, but the real question is, are you going for 240 crank or wheel hp? The 200 the CSi came with had 200 crank hp, so you really got about 160 rwhp when all was said and done.

The CSi already has a CAI. The air is coming from behind the headlights, and it doesn't get any colder than that. It even has a slight ram-air effect.

A hotter cam will move the powerband up. The stock CSi cam (if I recall right) is a 272. That makes it the highest OEM M30 cam BMW made for production. Moving the power band up also reduces it down low. A 284 is the best compromise, but it could knock your low-end torque down a bit. I highly doubt you'd see 15rwhp from a 272 to a 284, and even then, it would be peak hp, with some loss down low.

A P&P is all well and good, but if you are going to go through all that trouble, the thing that really gives you extra power is larger valves. Bumping the valves up to B35 spec will make it perform better, perhaps giving you 10rwhp.

The stock exhaust is pretty restrictive, but the place where you would get all the gains is in a set of headers. A guy on the E28 board is making Stahl replicas that would do the job.

 

[tripower]

Ah, but the real question is, are you going for 240 crank or wheel hp? The 200 the CSi came with had 200 crank hp, so you really got about 160 rwhp when all was said and done.

The CSi already has a CAI. The air is coming from behind the headlights, and it doesn't get any colder than that. It even has a slight ram-air effect.

A hotter cam will move the powerband up. The stock CSi cam (if I recall right) is a 272. That makes it the highest OEM M30 cam BMW made for production. Moving the power band up also reduces it down low. A 284 is the best compromise, but it could knock your low-end torque down a bit. I highly doubt you'd see 15rwhp from a 272 to a 284, and even then, it would be peak hp, with some loss down low.

A P&P is all well and good, but if you are going to go through all that trouble, the thing that really gives you extra power is larger valves. Bumping the valves up to B35 spec will make it perform better, perhaps giving you 10rwhp.

The stock exhaust is pretty restrictive, but the place where you would get all the gains is in a set of headers. A guy on the E28 board is making Stahl replicas that would do the job.

Headers of course as part of a complete exhaust replacement (that's goog for 10-15 HP). Weight reduction. For every 100 lbs taken off there is an approximate net HP gain of 10 HP. Lightweight flywheel. Lightweight battery (moved to the back for better weight distribution). High performance electronic ignition. High performance electronic fuel pump. Lightweight pulleys.

A couple of HP here and a couple there and it really adds up and I don't have to replace my engine. Reduce weight, increase fuel and air flow those will increase my power in an already rock solid engine.

 

[AndyM]

If my CSI came from the factory with 200 HP, I think bumping that up to 240 or 250 HP is doable,reasonable, and cost effective.

1. CAI intake (5-7 HP)
2. high flow exhaust (10 HP)
3. Hot cam (15 HP)
4. Port and polish head (10 HP)

Also there are plenty of areas to drop weight using fiberglass components and replacing some glass with lexan giving me an effective HP increase.

I'm not trying to rain on your parade -- but your D-Jet will probably run like sh*t if you do all of this without MAJOR tweaking (especially changing the cam). Having owned several D-Jet cars, its hard enough to keep a 30 year old analog fuel injection system working at all -- let alone handle a bunch of performance modifications. If you just bolt all this stuff on, it will idle like crap and the mixture will be all over the place throughout the rpm range. The D-Jet was designed to run a 3.0 with a stock cam, stock intake and stock exhaust. Everything the injection does is based on the manifold pressure (MAP) and coolant temperature at a given RPM. It has no O2 sensor and cannot compensate for performance changes out of the box. It was not really intended to be reprogrammed or adjusted in any way, other than slight idle mixture changes. Thus, as soon as you start making changes that would require a different mixture at a given MAP and RPM (headers=small change, intake=small change, hot cam=big change), the D-Jet still thinks the motor wants what it needed in the stock configuration. Each modification builds upon the others until the whole system is way out of whack. You might see dramatic improvement in one area -- like WOT at 4,000 rpm -- but it will be at the expense of driveability in other areas.

That said, there are ways to tweak a D-Jet to try to make it work (add resistors in line with the coolant temp sensor, screw around with the MPS, increase the fuel pressure, etc.) but you REALLY need to know what you are doing to make it work and I have never heard of one that actually works right in every situation -- even after hundreds of hours of screwing around with it. You'll get it to idle nice and clean, but it'll still lean out on the top end and vice-versa. I thought about trying to use the D-Jet on my 3.5 with a hot cam, mild porting and headers, but at the end of the day I realized it would be much more trouble and aggravation than its worth.

IMHO, trying to get the D-Jet to work with camshaft and intake changes just isn't worth it. I would suggest that if you want to keep the D-Jet, then keep the 3.0 stock and enjoy it. Go ahead and add the exhaust, add some timing, lighten the car, but leave the engine internals alone. If you want to mod your motor internally, work a programmable injection system into the plan. I did -- and couldn't be happier with it. It is difficult to tell the car isn't stock, but its completely tunable to compensate for the cam, high-comp pistons and headers. It runs smooth, takes off like a scalded cat and has power to spare. I have a wide-band O2 sensor and the system keeps the air/fuel ratio right around 14.7 during normal driving and drops it down to 13 or so at WOT. The whole injection cost well under a grand using off the shelf GM parts -- pretty much what a Megasquirt would cost you. I also completely rebuilt the 3.5 for under $1,500 with quality parts, but I understand why you don't want to go that route (and in fact I kept my 3.0 block just in case I want to go back to stock someday).

If you do go ahead and make the internal modifications PLEASE post the progress and results. I would love to hear that you found a combination that works with the D-Jet. And if it doesn't work, we can help.

 

[decoupe]

I guess it gets back to deciding what your priority is, originality or expediency. And whether you still have the $2,000 budget.

If cost is going to be THE factor then the 3.5 litre euro with complete L Jet swapped into your car for a $1,000 (see the second post in this thread) will give you the torque gain of displacement and the relatively hotter cam of the euro L Jet plus tunability and you can still do the exhaust. Best of both worlds.

If originality and keeping your current motor is the priority (though it won't be original if you do all of the things you listed), you are going to spend more money with all of the internal mods and exhaust system changes by a significant factor and probably not going to hit the same numbers without triple carbs, much hotter cam bigger valves etc etc. But then where is the torque going to come from? Definitely sounds like more than $2,000.

I agree about the weight reduction as a third path and am wandering down that myself though it is surprisingly expensive.

Either way have fun with it. What the hell, if the car is off the road for winter, what else do we do with all that spare time?

 

[tripower]

I'm not trying to rain on your parade -- but your D-Jet will probably run like sh*t if you do all of this without MAJOR tweaking

I don't remember saying that I was going to stick with D-Jet. Maybe a Motronic swap maybe carbs. Point is I don't need an engine swap. There are tons of mods (like exhaust) that I would have to make anyway with an engine swap that will improve performance in the stock engine.

 

[AndyM]

I don't remember saying that I was going to stick with D-Jet. Maybe a Motronic swap maybe carbs. Point is I don't need an engine swap. There are tons of mods (like exhaust) that I would have to make anyway with an engine swap that will improve performance in the stock engine.

Ah ha! That changes things signficantly. Assuming your 3.0 is stock CSi, you already have 9.5:1 pistons. Add a lumpy cam, port work, exhaust, electronic ignition and a fully programmable ECU and you're in business. I'd stay away from Motronic since its difficult to tune yourself and it uses the bulky AFM. Megasquirt can actually work with the low-impedance stock D-Jet injectors, so that would save a ton of money and aggravation.

You'll also see significant performance gains if you have your distributor recurved -- or better yet lock the distributor advance and let the ECU control timing. You can use an L-jet distributor with a VR-sensor to trigger a standard GM ignition module. Then that triggers a Megasquirt or another ECU which sends the modified timing single to an MSD 6A. This is is how I have mine set up.

Sorry I misunderstood -- I thought part of the goal was to use the D-Jet.

 

[tripower]

Ah ha! That changes things signficantly. Assuming your 3.0 is stock CSi, you already have 9.5:1 pistons. Add a lumpy cam, port work, exhaust, electronic ignition and a fully programmable ECU and you're in business. I'd stay away from Motronic since its difficult to tune yourself and it uses the bulky AFM. Megasquirt can actually work with the low-impedance stock D-Jet injectors, so that would save a ton of money and aggravation.

You'll also see significant performance gains if you have your distributor recurved -- or better yet lock the distributor advance and let the ECU control timing. You can use an L-jet distributor with a VR-sensor to trigger a standard GM ignition module. Then that triggers a Megasquirt or another ECU which sends the modified timing single to an MSD 6A. This is is how I have mine set up.

Sorry I misunderstood -- I thought part of the goal was to use the D-Jet.

So you are saying use the MegaSquirt box in place of the original D-Jet FI box? Are there any MegaSquirt DIY's for our cars? Do you have a web page or DIY for your setup?

I found these posts of your setup:

http://www.e9coupe.com/forum/viewtopic.php?t=50&highlight=megasquirt
http://www.e9coupe.com/forum/viewtopic.php?t=876&highlight=megasquirt

Very nice. I wish you had a full DIY with part numbers,vendors, tools used, etc. That could be an awesome writeup for guys who want to do the same thing!

 

[AndyM]

I've been meaning to write it up, but just haven't found the time. I finished the BMW and now I'm swapping an '07 Vortec 5.3 into my Jeep. Nonetheless, here are the highlights:

Its a little more involved than just repacing the D-Jet ECU. You need a new harness and all of the D-Jet sensors really need to be replaced as well, but its not really that hard. Megasquirt and most aftermarket ECUs generally need the following to operate:

IAT - intake air temp sensor
CTS - coolant temp sensor
TPS - throttle position sensor
MAP - manifold pressure sensor (usually in conjunction with or in place of an air flow meter)
AFM - air flow meter (not necessary on Megasquirt and some GM-based systems)
O2 sensor - lets the ECU trim the mixture within limited parameters
Idle bypass valve - let's in more air when cold - can either be a simple switch (like L-Jet) or controlled by the ECU for full idle control under all situations
Ignition trigger -- some way to produce a signal that the ECU will recognize

Those are your major components. It is extremely easy to add the IAT, CTS, MAP sensors to you stock D-Jet manifold. O2 sensor just requires a bung welded into one of the exhaust downpipes. The TPS is a little tricky, but not a big deal once you find the right one. I found one from a Ford Mustang that is compatible with GM and Megasquirt. You may even be able to use the stock auxillary air valve thingy under the manifold. Then your left with figuring out how to trigger the ECU and mounting up the injectors.

There are numerous ways to trigger the ignition and the ECU. Most ECUs use either a Hall sensor or a VR sensor. My goal was the keep the motor looking as stock as possible, so I used an L-Jet distributor with the stock VR sensor. You can run that straight into most aftermarket ECUs and they'll recognize the signal, then send out a signal to trigger the coil or an MSD. Some ECUs may require converting the signal through a GM ignition module first, but that's no big deal. You can either let the distributor handle the timing, or convert it over to full timing control. I did full timing control. I disabled the advance in the distributor by removing all the guts and epoxying the two pieces of the shaft together.

Then you'll need to figure out your injectors. I have a Megasquirt I built a few years ago, but I didn't actually use it on my coupe. Instead I went with a GM ECU intended for a tuned-port V8 and reprogrammed it to run the six cylinder. This required changing out all of the D-Jet low impedance injectors for some high impedance ones that are compatible with the GM ECU. The problem is that the typical Bosch-style high impedance injectors have a different fuel rail mount that require custom machined caps or some other unique method to properly mount them. In hindsight, that was a lot of trouble to go through.

I believe Megasquirt is actually configurable to run the D-Jet low impedance injectors without frying the injector drivers. You can either run external resistors, or set it up with a programmed solution -- its been a while since I looked into it, but I believe they called it pulse width modulation. Check out the Megasquirt site for more info. So in theory you should be able to reuse your stock D-Jet injectors, fuel rail and regulator with the Megasquirt. I haven't tried it, but wouldn't hesitate to do so.

The final big item is a wiring harness. You can't really reuse the D-Jet harness since none of the connectors are compatible. I carefully removed mine and stored it away with all of the other stock D-Jet parts (I figure they may be worth something some day). Then I made up a new harness using wiring and connectors from here:

http://www.rs-autosport.com/

The wires were only long enough to reach under the dash. If I had to do it over, I would get extra long wires and run it all the way back to the stock location.

This isn't intended to dissuade you from upgrading the injection. It is absolutely worth all of the time and effort. Plus, this is easier in most respects than a motronic conversion using the D-Jet manifold. I think the only part that is more difficult is the harness, but Megasquirt makes that relatively easy, too. I believe there are a couple of people on the board who are actively investigating/installing a Megasquirt. Hopefully they'll chime in with an update -- or tell you what I missed or got wrong.

 

[velocewest]

Sorry I misunderstood -- I thought part of the goal was to use the D-Jet.

Likewise, that's what I interpreted from the original "resurrection" post. I stand by my comments regarding the benefits of a 3.5 swap. There's nothing special about a Euro 3.0 block, other than the originality to the car. You can always store the original engine for the possiblity you want to return the car to factory spec.

My e12 has a 3.5 with 10:1 pistons, a Schrick 284, and runs Motronic from a 533i with a chip. Intake is stock Motronic, exhaust is euro e34 manifolds and downpipes, which are sized for the M30B35 engine. It's got more bottom end and nearly equal top end to any stock M88/S38 powered car I've driven. You could create an equivalent to my engine for $1500 easy.

Next phase for my coupe is MegaSquirt. I'm going to use L-jet intake for the CSi look, and EDIS for distributorless ignition. Initially it will go on the 2.8 block, but I'm building a 3.5 block and will probably turbo when that goes in.

 

[MichaelP]

I don't know if D-jet is compatable with Megasquirt either, but L-jet is. A Megasquirted L-jet would look visually identical to the same with D-jet. I'm planning on going that route once I get my coupe off its jackstands. A full L-jet system is cheap and easy to rig up. See:
http://www.bmwcsregistry.org/Technical/EFIConversion.html

The Megasquirt/L-jet setup is heavily documented over on the FAQ section of http://www.firstfives.org . You might want to get in touch with Peter Florence on that board. He's a whiz with this stuff and one of the most patient and helpful people you could meet.

With a tuneable EFI map, you could A) remap to put the power band where you want it and B) then change your engine internals and remap to your heart's content.

 

[AndyM]

The D-Jet and L-Jet intake logs are interchangeable for the most part, but they aren't identical. The throttle bodies are significantly different, too. Unless you're working with a carb'd car and have a complete L-Jet system lying around, it seems like a lot of work to convert from D-Jet to L-Jet electronics, then convert to Megasquirt. I'd just skip the L-Jet part and go with all new wires and sensors since it'll be about the same amount of work.

 

[MichaelP]

but they aren't identical

No they're not. I said visually identical. Part of the issue here appears to be an original appearance. The point is that if Megasquirt isn't compatible with low impedance injectors, then L-jet becomes a plan B option that doesn't look different -- and is proven to work with a significant knowledge base out there.

 

[AndyM]

Gotcha -- but they aren't visually identical. The D-Jet "log" has a different shape and a rougher casting -- that's all I was saying -- sorry I wasn't clear. Tough critics can tell the difference immediately if you are trying to retain stock appearance. You are absolutely correct that the injector mounting bases and the runners are the same and are fully interchangeable. Fuel rails and regulators are different, but similar and are interchangeable on the manifold base. Same with the throttle bodies. You can pretty much swap whatever you need to between the two systems to make something that works. BTW, if I had an E12, I'd be all over that "plug-and-play" L-Jet to Megasquirt conversion.

 

[tripower]

See:
http://www.bmwcsregistry.org/Technical/EFIConversion.html

This first link is broken, and has been for a while. Is the site no longer in existence?

 

[MichaelP]

Works fine for me. Try a different browser. There's a goofy-assed, changing picture on the CSR that runs on the background which might be confusing your browser.

Or, go to the CSR homepage ( http://www.bmwcsregistry.org ), then Technical > Dual Carbs to L-Jet Upgrade (under Modifications / Swaps /Upgrades).

HTH

 

[tripower]

Works fine for me. Try a different browser. There's a goofy-assed, changing picture on the CSR that runs on the background which might be confusing your browser.

Or, go to the CSR homepage ( http://www.bmwcsregistry.org ), then Technical > Dual Carbs to L-Jet Upgrade (under Modifications / Swaps /Upgrades).

HTH

Nope, dead as a doornail. IE7 and Firefox, can someone else try this?

 

[x_atlas0]

Works just fine for me.

 

[velocewest]

CSR website works for me in both IE7 and Firefox.

 

[MichaelP]

Tripower, send me an email and I'll bounce a pdf of the page back. The pictures will be kinda tiny, but it's still worth a read.