Judging from a prior post read by more than 500 with 50 plus commentaries, the fact that a V8 540i with considerably more torque can out-accelerate our E34M5's is disturbing to many. And, indeed it will, with our only recourse to hopefully pull away at higher rpms when our HP comes fully on cam. And worse, as someone pointed out, the 540i owners know it and are smug about it.
If you want to beat a V8 540i, even the later models, I think there's a simple solution. It's to install both a chip and a Dinan exhaust cam sprocket. I explored this before by showing how it would be expected to impact on the E34 M5's torque and HP figures versus late model 540is. I copy this post below for your information.
I have no doubt the chip plus the cam sprocket really deliver on the torque (the sprocket is key) because I just installed both on my M6 and the dyno results showed a 50 ft/lb increase in rear wheel torque at 4500 rpms, resulting in a 65ft/lb increase at flywheel. This is more than a 25% increase and produces a big gain lower down the rpm band than stock which was a total of 256 ft/lbs at around 5000 rpms (and now 310 ft/lbs). By the way, with these changes, I'm pretty sure my M6 will now out-accelerate my 93M5 (3.6L), and am planning a street race shortly just for fun.
As for my 93M5, I do have a Conforti Chip, but haven't added a Cam sprocket because I'm installing a custom made supercharger soon, and in this context the wider valve overlap introduced by the cam sprocket would actually subtract from increased power.
More generally, I think the E34M5 is a gorgeous car and the option is there for us to keep it on the competitive edge. Sure the chip plus cam sprocket isn't cheap, but I reckon they cost only about $40 per ft/lb of torque gained, and with 60lbs of increased rear wheel torque, we'll be restoring our honeys to the glory they deserve.
Hope this proves inspiring.
Samson
Thread
In a prior post, I suggested that one of the reasons 'chips' don't deliver the HP and Torque that's touted by the manufacturer is because a 'chip' should really be combined with an exhaust cam sprocket. The purpose of this post is to relate my understanding of (1) why this is so, (2) summarize relevant dyno results, (3) profile the possible performance gains in comparison to performance of the 540i, and (4) illustrate likely costs. I don't presume to have it all right, however, and welcome corrections and suggestions by readers.
1) Why combine the two. When we buy a Dinan or Jim Conforti Chip we're trying to alter ignition and fuel in a way that renders a more powerful mix when the cylinder fires. Now that we've succeeded in doing this, there's a related question: How fast is the burnt or spent fuel in the cylinder dispersed or sucked away to make room for the next injection/burst of fuel. The answer involves the exhaust cam sproket because it determines the "overlap" period when both intake value (in comes the fuel) and outtake valve (out goes the exhaust) are operating. Relative to the stock exhaust cam on our M5s, a "sport" exhaust cam has a wider lobe and, as a result, keeps the exhaust value open longer. This, in turn is conducive to producing a broader power range. And specific to our M5 engines which are "Horsepower engines" (more HP than Torque), the sport cam sprocket helps generate more torque at lower rpms (which is what we really want). In short, a chip and exhaust cam sprokect are complements that work together, not individual, independent performance modificaitons.
2) Dyno results. You may have noticed that it's very difficult to get dyno results on both chip and exhaust cam sprocket. This is because only Dinan provides this information because ONLY Dinan makes an exhaust cam sprocket for our M5s. This is not the case, for example, for my 88M6 where a lot of replica cam sprockets exist, including a unit produced by Dinan. So, unfortunately, we can't discern from stats available how a Conforti chip or a Mark D'sylva chip combines with an exhaust cam sprocket. The only data we have for our M5s is for a Dinan chip and Dinan cam sprocket.
For our M5s, a Dinan chip claims a PEAK 37 HP gain at 7000 rpms and a PEAK 36lb/ft of Torque gain at 3500rpms. Add the exhaust cam sprocket, and Dinan claims a PEAK 54HP gain at 5500rpm and a PEAK 52lb/ft of Torque gain at 5000rpms. So instead of the M5s stock 311HP at 6800 rpms, the chip and cam sprocket generate about 350HP much lower down the rpm band, at 5000, and that's where we want it, lower down the rpm band. And instead of the stock 266ft/lbs of torque at 5000 rpms, the chip and cam sprocket deliver 293 ft/lbs at 4000 rpms and 318ft/lbs at 5000 rpms.
3) Chipped and cammed M5 vs. 540i. I make this comparison because the 540i is part of the 5 series family and is also a 4 door, both weighing in at around 3800lbs. As I said in my prior post on "Appeal of a 4.10 differential", BMW is evolving the 540i (since 1996) into a torque monster relative to our M5. Stock TQ in the post 96- 540i is around 330 ft/lbs at 4000 rpms -- exactly where one wants it if 0-60 acceleration is a concern -- and yet the 540i has only a 282 HP engine. In short, it's a torque engine vs. our HP engine.
Ok, the comparisons I'm going to make now have our M5 with chip and cam sprocket vs. a stock 96 and then 98+ 540i. This may not seem fair, but a chip doesn't do a lot for these later 540is because they are already pretty efficient (ie., a chip increases HP and TQ only 10 points) and there is no exhaust cam sprocket for them.
So, at 4000 rpms our stock M5 produced 262 ft/lbs of torque vs. 288 for the 93-95 540i, 330 for the 96-98 540i, and 332 for the 98-2001 540i. With chip and cam sprocket, our M5 increases to 293 ft/lbs at 4000. Better news is that at 5000 rpms, our stock M5 produces only 266 f/lbs of torque vs. 307 for the 93-95 540i, 295 for the 96-98, and 297 for the 98-2001. With chip and cam, our M5 generates 318 ft/lbs of torque at 5000 rpms, exceeding all the later 540i models. And by 6000 rpm, our stock M5 torque goes from 263 ft/lbs vs. 243-245 for the post 96 540i's, whereas with chip and cam our M5 produces 306 ft/lbs.
With these increases, I have no doubt that our M5's 0-60 performance would improve considerably, but may still not match the 6 shift 540i (which is faster), whereas we'd easily beat the 540i in the 1/4 mile sprint. But, as I said in my other post, if we really want winning accelerating on all fronts (from 0-60) we'd have to make better use all that increased chip and cam power by replacing our current 3.91 or 3.73 rear differential with a 4.10. And, though costly and rare, there is a supplier who will custom make one for us (see my post on the 4.10 differential).
4) Cost and Installation: Again a comparison might be useful. For my 88M6 a conforti chip costs around $250 and I can find an exaust cam sprocket (not by Dinan) for around $125. Dinan's cam for my M6 is about $250. Installation is 5hrs (say $400) and if/when you do it, good time to replace your timing belt because they're all connected to the same pullies in the same area of the engine. For the E34M5, same price for the chip, but Dinan has a monopoly on the cam sprocket. Cost is $561 and 6 hrs. (figure $450) to install. By the way, no problem mixing, say, a Jim Conforti Chip with a Dinan Cam Sprocket -- they are compatible.
Finally, let me say there's a nice little mini survey of chip owners in a hidden section in the BMW Enthusiast's Companion, pp. 258 that says while most chip owners were satisfied and some were not, those chip owners who also had a cam sprocket "were a very happy bunch".
Hope this information is of some value. Welcome feedback. Cheers.
Brandon
Linear Mode
