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Originally Posted by Chrisyphus
First of all, Holy smokes, what a spec. Man, this is one of my two dream specs (alternatively, all the same options but in Melbourne. Not sure if that would be too much red or not, I have never seen that spec)
And the build you're putting together... you've got excellent taste and know excellent fabricators!
Having said all of that, those power numbers are... unbelievable. I feel like I am missing the plot somewhere? I cannot wrap my head around how you're down a full hundred wheel horsepower and nobody is talking about that.. There must be something seriously wrong.
I promise my goal here is not to rain on your parade or anything like that- I am genuinely concerned for you. You're clearly in love with this car and spending a ton of money on perfecting it, but it seems to me that there is a major issue just under the surface somewhere.
Additionally, for a car with, ostensibly, such a pristine history- no Winter miles, Single owner, super clean interior and exterior, the engine bay is an absolute mess. The secondary air pump, in particular, screams 'flood damage' to me. The way there's a layer of ultra-fine dirt caked on top of it, as if water left it there, is an extreme Red flag. Beyond that, the entire engine bay has a substantial amount of silt-like dirt that doesn't compute to me. Then there's all the corrosion on the Aluminum... I think that you were misled about the care your car received, at best.
Hopefully, I am just too deep into my own fiction, and when you dyno the car again, all is well. Maybe your cats were just incredibly clogged and choking the engine, or maybe you had really bad fuel like you mentioned... your dyno graph, in addition to being unbelievably low, has another anomalous feature- it absolutely flatlines at 6500, as if it hit a ceiling and started bouncing off of it. It is quite typical for these engines to see the rate of climb reduce at or around 7000 RPM, but it still climbs to peak at around 7900.
Your dyno operator was terminating the pulls around 7500. I can understand why he was doing this. The car isn't making any more power. Why wind it out? But I am curious if he was doing it for any reason beyond mechanical sympathy? Was something strange happening? It almost seems to me like the car was being choked by something or that it was aggressively pulling timing for some reason, but I would expect either of those scenarios to throw some code... something at least?
Have you done any compression or leakdown testing? Was your dyno operator datalogging while doing the dyno runs? If so, and you're willing to send them to me, I can have our tuner take a look for anything that jumps out at him. We have tuned a bunch of E9x M3s, and would be willing to take a look (in this unusual case) out of curiosity more than anything.
Moving on to some other topics that have been mentioned- ported heads and cams to get 400+ wheel; Just last month, we had a car come through the shop with a nearly identical setup- Eventuri, full exhaust, etc., and was making around 375 wheel horsepower, which is quite typical on our Mustang dyno.
After installing refreshed, but stock heads and a set of Schrick cams, he made 408 wheel horsepower. The assessment that ported and polished heads aren't critical to gaining power, as the head is exceptional in its original form, is mostly correct- there are a few wizards out there that can make gains in these heads, but most places do more harm than good, and there's not yet a terribly clear understanding of why that is.
Some people are claiming that improper profiles are causing trans-sonic conditions in the intake ports, allowing shockwaves to occur in the port and choke it rather than opening up additional flow. I am not convinced this is the case based on fluid studies I've conducted recently... I think there is a general misconception about the benefits/drawbacks of higher velocity airflow and its impact on air density in relation to cylinder filling, and very few people have a complete understanding of the entire system in operation; thus, most shops doing port jobs are making incorrect assumptions based on instinct and gut feeling, leading to poor results. Without question, I do not yet, but the math I worked out for my velocity stack redesign and the profiles it generated were antithetical to nearly all of the "conventional wisdom" I found from non-academic sources, and I doubled the next best gains to date without DME tuning, so I think I am starting to get somewhere. The trouble is that the Vstacks are the easy part, so I need to keep doing studies and research. I digress.
The upshot of all of that is: assuming your motor is healthy and making more typical numbers: ~370wheel, 400 wheel is absolutely attainable with a set of cams and stock heads, assuming that is a road you're interested in going down still.
Regarding strokers, we offer a 4.6L setup that utilizes a proprietary piston co-developed with JE exclusively for our 4.6 builds, allowing us to retain stock-length rods, thus reducing piston velocities, side loading, and acceleration forces overall. We aren't ready to publish power figures yet, but it is impressive.
Finally, M3SQRD probably knows more about the E9x M3 platform as a whole than anyone else on this board. He is also extraordinarily hard to impress, and because of his professional background, understands the manufacturing processes and (more importantly) the effects nearly any mod will have on these chassis better than anyone I have ever seen. All the while, having a nearly encyclopedic knowledge base about all the various options in almost every category.
If he says something is good or bad, that has a significant impact on my opinion. We have made design and vendor changes for some of our products based on his feedback. Despite the differences we have had, he is an extraordinarily valuable member of this community, and I highly recommend that, especially for a build of this caliber, you heed his advice on which products to choose and which to disregard.
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First off, thank you for your detailed analysis of my situation, you have a keen eye for these things.
Second, I am very fond of your shop, Partee Racing. I recently watched a video of you guys doing a complete overhaul of a S62 engine with M539 Restorations. Clearly, you guys know what you're doing and since I have an E39 M5, the thought of driving down there and getting the entire engine done is something I've seriously considered. After all, you're only 500 miles away from me
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Now, back to the E92. The car was in a great shape internally when I bought it. The reason for some of that dirt and grime you saw was most likely because the previous owner parked it outside for several months before selling it, as evident by a ton of leaves and debris inside the drain channels under the hood. It's all cleared out now and the bay looks much better than before.
The paint is a different story. Lots of tree saps sat on it for quite a while so a lot of paint correction will be needed after I'm done with the mechanicals. There are also splashed concrete strips on the driver side door and under the wheel arches. That all will be taken care of as well.
Regarding the dyno. I was expecting around 330 whp, but got a lot less and the reasons came down to a few things. A factory vehicle is meant to produce max power right at the red line. This engine is peaking almost 2000 RPM bellow that. I have a video of the dyno and I noticed black smoke shooting out the exhaust around 7500 RPM. It was running really rich. The spark plugs are of the ion sensing knock detection variety and they are fairly old. by my estimate they are pulling at least 10 degrees of timing at the top end, leading to significant power losses. We've already installed new ones from NGK as well as new OEM ignition coils. That should rectify the problem.
Your theory regarding the heads and porting them is quite interesting. For the time being, due to cost and time reasons, we have decided to avoid touching the heads, minus replacing the valve cover gaskets as they were a bit leaky. Upgrades for gaining power and reducing powertrain losses at the current stage include, on top of the previously mentioned coils and plugs, Full custom titanium catback exhaust, Eventuri intake, Single mass flywheel with a twin organic clutch, CF drive shaft, and a tune.
As mentioned in previous posts, we've done the precautionary maintenance items such as rod bearings, vanos covers, and throttle actuators. Reliability is the utmost priority here. We are not chasing absolute power numbers.
I have seriously considered a stroker build with dry sump, but the costs seem astronomical. This is definitely a build I am keeping NA. Correct me if I'm wrong here, does the 4.6L stroker build you guys offer require shaving off the Alusil coating? I've heard the max displacement you can get with a S65 is 4.4L if you want to leave the cylinder walls alone.
Here's an incomplete list of what we are doing to the M3. It's just a build order so it changes constantly but it should give you a better idea of the overall picture.
Thanks again for your concerns and willingness to help! I appreciate experts chiming in because there's always more to learn.