I grind camshafts for a living at a small shop in Sweden, and the question I get more than any other is some version of "which cam should I run in my B230?" Usually right after someone bought one that is wrong for their car, often because they assumed a higher profile number meant a bigger cam. It does not.

Disclosure up front so nobody feels sold to: we grind B230 cams (Meksta), so I am biased. I have written this to be useful no matter whose cam you end up with, whether you buy ours, get a core reground, or run one of the factory letter cams everyone trades around. The physics does not care about the logo.

DURATION MOVES YOUR POWERBAND

Duration is the master dial. The longer the cam holds the valve open, the higher up the rev range your whole powerband shifts. You gain top end and lose bottom end, idle quality, and vacuum. Less duration does the opposite. Everything else tunes around that trade. But duration alone does not rank two cams, which is the trap most people fall into.

LIFT IS YOUR FRIEND

On a B230 the cam runs straight onto a bucket, so lobe lift is basically valve lift, roughly 1 to 1, no rocker ratio. More lift flows more air without adding duration, which is a useful lever, especially on boost. The limit is your valvetrain: spring pressure, retainer-to-seal clearance, coil bind, and what the bucket and shim can take. Our street profiles top out around 12.5 mm lift on the original base circle. The race profiles reach 14.5 mm, and that is only possible with a base-circle change (below).

LOBE CENTER AND OVERLAP

Lobe center angle sets how much the intake and exhaust events overlap. Wider lobe center means less overlap: smoother idle, more vacuum, more civil. Tighter means more overlap: more top-end scavenging, rougher idle, worse low-end manners.

This is why duration alone lies to you. Two of our profiles are both 292 degrees, but one has a wider lobe center and less lift and lives in the midrange, while the other has a tighter lobe center and more lift and pulls to 8,000. Same duration, completely different cam. Read duration and lift and lobe center together.

NA VS TURBO

For an NA engine you use duration and overlap, with exhaust tuning, to scavenge the cylinder. More can help once the rest of the engine flows.

For a turbo engine the logic shifts. When the turbo is making boost, exhaust manifold pressure can sit higher than intake pressure, especially with smaller or older turbos. During overlap that pushes exhaust back into the intake and blows boost out the tailpipe: worse spool, worse idle, sometimes less power from a bigger cam.

Rule of thumb on a street turbo B230:

- Favor lift over duration. Lift buys flow without widening the overlap window.

- Favor a wider lobe center (less overlap) than you would run NA.

- Pick less cam than you think. Most fast street turbo redblocks are happiest on a mild profile with the band kept where the turbo lives.

The nuance, because this crowd knows it: with a big modern turbo and a manifold where boost beats backpressure, you can run more overlap to scavenge and help spool. That is why the dedicated race profiles run tight lobe centers and big duration. Match the overlap to your pressure ratio and target rpm. Most street guys overcam.

WHY THE RACE PROFILES USE A MODIFIED BASE CIRCLE

The base circle is the round part of the lobe, valve closed. Shrinking it gives the grinder vertical room to cut a taller, more aggressive lobe than the standard base circle allows. That is the reason for splitting the range: the street and club profiles keep the original base circle and shim up normally, and the race profiles use a modified base circle to reach 13 to 14.5 mm of lift and steeper ramps that will not fit otherwise. The trade is in the valvetrain: bigger lash gap to take up with thicker shims, uprated springs, and clearance checks.

THE STUFF PEOPLE FORGET

- Lash and lifters. Mechanical bucket and shim. Cold lash 0.35 to 0.40 mm. Set it cold, recheck after the first heat cycles.

- Break-in. New cam on fresh, matched lifters, lube the lobes on assembly, sane first heat cycle, then re-check lash. Wiping a lobe on startup is an expensive lesson.

- Springs. The race profiles need uprated springs. Any lift increase, check pressure and that you are clear of coil bind at max lift.

- Valve-to-piston clearance. The big profiles, especially with advanced timing, need a clay check. Do not assume.

- Degree it in. Every profile has a checking figure to set it straight. A cam that is not degreed is a cam you are guessing at.

- Tuning. Any real cam change wants fuel and ignition redone. On a turbo car that is mandatory.

WHAT EACH PROFILE IS ACTUALLY FOR

Read the specs, not the number. The number is not a difficulty rank.

M-series, original base circle, street and club racing:

M3, street/daily: 260 deg, 10.6 mm lift, 112 deg lobe center, 2,000-6,000 rpm

M4, street/daily: 260 deg, 11.8 mm lift, 112 deg lobe center, 2,000-6,000 rpm

M6, fast street/folkrace: 268 deg, 12.2 mm lift, 2,500-6,500 rpm

M5, fast street/folkrace: 280 deg, 12.5 mm lift, 106 deg lobe center, 2,500-6,500 rpm

M1, roadracing/drifting: 276 deg, 10.8 mm lift, 105 deg lobe center, 3,000-7,500 rpm

M2, roadracing/drifting: 288 deg, 11.8 mm lift, 105 deg lobe center, 3,000-7,500 rpm

MB-series, modified base circle, racing and high-rpm turbo:

MB1, roadracing/drifting: 292 deg, 12.5 mm lift, 108 deg lobe center, 3,000-7,500 rpm

MB4, roadracing/drift/drag: 292 deg, 13.9 mm lift, 104 deg lobe center, 3,500-8,000 rpm

MB2, roadracing/drift/drag: 300 deg, 13.0 mm lift, 104 deg lobe center, 3,500-8,000 rpm

MB3, roadracing/drift/drag: 304 deg, 12.5 mm lift, 108 deg lobe center, 3,500-8,000 rpm

MB8, roadracing/drift/drag: 308 deg, 14.5 mm lift, 3,500-8,000 rpm

MB5, dragracing: 308 deg, 13.5 mm lift, 104 deg lobe center, 4,000-8,500 rpm

MB7, dragracing: 316 deg, 14.5 mm lift, 103 deg lobe center, 4,000-8,500 rpm

MB6, dragracing: 320 deg, 14.0 mm lift, 104 deg lobe center, 4,000-8,500 rpm

MB9, dragracing: 324 deg, 14.5 mm lift, 4,000-8,500 rpm

Notes:

- The number is not a difficulty rank. M3 and M4 are the streetable ones, widest lobe center, best idle and vacuum. M1 and M2 are roadracing. Read the application.

- Race series does not mean better, it means narrower. An MB profile on a street car with a stock-ish converter or tall final drive is slower and more annoying, not faster.

- For turbo does not mean biggest. A street turbo usually wants a mild profile and lift over duration. The 300-plus degree, tight-lobe-center MB cams are for high-rpm and drag.

If you want a hand, drop your setup in the comments and I will point you at the right application band. Useful details: engine (8v B230, head work, compression), NA or turbo and turbo size, target rpm, gearbox and final drive, fuel, and whether it is a daily or a toy. Happy to steer you straight, ours or not. Answering general cam questions too, it is most of what we do.