Sunbelt cams

[whiltebeitel]

Yeah, I know what uder/over-square means. What are you doing to the head to make it survive that kind of RPMs? Just making a short-stroke motor doen't make it king shit.

[asubimmer]

Everything is coming off the head, workin the head over and then putting in new everything? What would you expect? Thats about all the specifics that are coming out untill its finished ;)

[C-T]

When I get my Schrick grind, we can set up some pulls when I'm in the Bay. The Schricks have WAY more usable power below the curve and in the mid-range. Sunbelts aren't worth the low-end loss and make only 5-10 whp more up top.

I tend to agree. I chose Sunbelts for my car when the the cams were still new, and the Seth Thomas M3 had just dyno'd 270 whp on AA's Mustang dyno, which was known to read low, with just the cams and basic bolt-ons. They were the Jesus cams, and while ultimately I was able to get some good power out of them, I would have made more low/midrange power out of the gate with Schricks rather than having to play around with the Sunbelts. For a street car, unless you are prepared (and competent enough) to play around with the Sunbelts, and they can be tricky when it comes to header selection, etc, the Schricks are going to be more satisfying for a default install. Especially for a street car.

In the end, this was the best dyno I had when the engine was finally sorted in the M3:



Great TQ, and more than acceptable whp for stock headers. I have since seen similar or better dynos as Bimmerworld has really nailed the tuning on these cams, but if I had to do it all over again, well, I don't know. The S52 just isn't a high-RPM monster like the S54, and there's nothing to be done to make it one. Knowing what I know now, I would probably choose the Schricks to maximize the potency of what my engine does best.

[MIKe30]

Knowing what I know now, I would probably choose the Schricks to maximize the potency of what my engine does best.

I hate it when you talk like this!! Wish it wasnt raining here so I can drop this damn motor in. Would like to see sunbelts w/euro headers. Hope i'm in for a surprise... a good one that is...

[M-technik-3]

Just started raining here going out to finish pulling an engine and install the light weight flywheel.

[C-T]

I hate it when you talk like this!! Wish it wasnt raining here so I can drop this damn motor in. Would like to see sunbelts w/euro headers. Hope i'm in for a surprise... a good one that is...

Don't get me wrong, the Sunbelts are potent cams. Very much so. Bimmerworld has also perfected their tuning to the point where the TQ loss in comparison to the Schricks is as minimized as it's going to get, but the Schricks are what they are - Capable of higher low/mid power and TQ. It's just a choice you make. However, the loss is recovered by the greater high-RPM power of the Sunbelts, and this can and will result in a faster car depending on the setup, and how you plan to use the car. This is critical, because someone that spends the majority of their time at 4500+ RPM will have better results from the Sunbelts, as opposed to someone that needs a broader, less peaky powerband, and who will likely benefit from the Schricks instead. "Race" vs "Street." TQ/Midrange vs Maximum high-RPM power. It's the classic NA tradeoff.

You will be very happy with your Sunbelts, just as Polak will love his Schricks. What rear end do you plan to run? Bimmerworld suggests a 3.73 with the Sunbelts for maximum peformance, but that's with the ZF and is really best for a race car, as without a 6-speed a 3.73 is brutal on the street. I ran a 3.64 in my M3, and while it mated well to my engine, gas consumption was just short of ridiculous.

Here's two useless videos I dug up of my 97 M3 v. a friend's 97 M3.

Me
Sunbelt cams, weak tune - 256 whp / 236 TQ
3.64

v.

Friend
Schrick cam kit - 253 whp / 234 TQ
3.46

Of course the deck is stacked in my favor because, despite making similar power at the time, my engine had a lot more to it than a cam kit. But it does illustrate pretty well the midrange of the Schricks, because in most of the contests, the Schrick car would hop on mine at the start, and then get reeled in and passed:

Inside the Schrick car:

http://www.youtube.com/watch?v=BmzwSXBxLaQ

Inside my car:

http://www.youtube.com/watch?v=j3zJGHKlYTk

Notice that, when my car finally starts catching up, that it's not like I hit hyperspace and disappear. If anything, the videos illustrate how decently matched the cams are, and how each has its own strength and different sweet spot in its powerband. Both cams are capable of great power numbers in an S52, power that was at one time the province of FI when I first got my start modifying my M3 in what seems another lifetime, and will result in a supremely satisfying powerplant in an E30.

[rneedham1979]

1+ its called usable power band, the sunbelts make more power over xxxx rpm but doesn't not mean they make more power through the entire power band.

When I get my Schrick grind, we can set up some pulls when I'm in the Bay. The Schricks have WAY more usable power below the curve and in the mid-range. Sunbelts aren't worth the low-end loss and make only 5-10 whp more up top.

[redmist]

Ok if you are going na, not ok if you are going FI. I'm not going to explain why, do your research.

[e30polak]

Great vids C-T! While there is a good illustration of the cam difference, you also had shorter gears, which put the runs in your favor for the most part. ;)

[C-T]

Among other things, my engine overbore and forged pistons (that are about half the stock weight) had something to do with it as well. :D

[e30polak]

Among other things, my engine overbore and forged pistons (that are about half the stock weight) had something to do with it as well. :D

I guess so.... ;)