Non-VW Engine Tuning Article

[gimmesomeshelter]

I found a little article describing how they increased the HP of a lowly MG engine with some head work, a cam update, and a little time on a dyno.

https://classicmotorsports.com/articles/how-make-mgb-three-seconds-quicker-six-steps/

Cheers,

Paul
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[Alstrup]

Apart from a misinterpretation of engine behaviure here and there, nice article.
"We", that is mostly my colleagues at Westspeed do a lot of similar upgrades, mainly in conjunction with an overhaul though.
Engines like that, MG, Mini, Triumph etc. with siameezed ports like scatter cams. Not many shops use them though, mainly because they add to the cost of the engine, and probably also the fact that not many understand the concept, but in an engine like the one they worked on in the article they could easily have gained some 5% more usable torque below 4500 rpm without loosing upper rpm power. Another giveaway is the fact that the engine wants 35 degrees total timing to perform its best. That tells us that either the mix quality is poor or the porting has created a rich spot right at the spark plug, or the ignition system is weak.

That said, a 1000 rpm increase in powerband is significant, and WILL make the car much more fun to drive.
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[henry roberts]

Alstrup, i have been watching some of David Vizard's talks and had wondered if a scatter pattern cam might be of use with our single port heads.

Any thoughts?

As an aside, i so wish David Vizard had taken an interest in 36 and 40hp motors.

[Alstrup]

Hello.
Yes, that could have been fun, but I guess there was not enough customers for that.
Wrt scatter cams. They are only interesting in engines that have both siameezed and isolated in/ex ports. For instance on the MGB. It has "straight through" exhaust ports on cylinder 1 & 4, but siamezed ports on 2 & 3. So what you do is that you make one grind pattern for 1 & 4, and then another grind for 2 & 3 in order to compensate for the exhaust ports there.
With VW sgl port heads a simpler split duration and split lift cam can improve overall performance quite a bit. A few tuners have used it for a long time. Most didn´t, mainly because the consensus was to go dual port as it was easier hp.

I am not entirely sure who it was, maybe Ray Vallero, did a smaller displacement type 3 sgl port engine some 30 years ago. I believe it was 1680 cc. He exploited the split duration and split lift to the max, at least for the time, and I remember that everybody was amazed as to how hard this type 3 pulled.

Scatter cams would also be interesting on a flat head V8 if you were chasing both power and driveability, I have never seen anyone do it though, which has puzzled me as to why not. I think the reason is that people think that it is not worth the hazzle. Some day, after I retire I will most likely build one just to prove my point
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[henry roberts]

note: i have zero experience or proof and am just repeating what i read (i cannot even remember where)

i have read that cylinders 1 & 3 have less cylinder filling being only 180º after 2 & 4. no idea if that is single carb or rpm specific.

provided this is true, my thoughts are, if you altered the cam timing (be it intake/exhaust/or both) on 1 & 3 to both improve cylinder filling and maximise the output for the charge available to bring the output up on those two cylinders (and hence the motor as a whole).

if only i had the knowledge and skills to test the idea. 😂

[Alstrup]

There is - some - power robbing going on, yes. If you have the tools to measuare cylinder pressure through the rpms you do do a simple test with adding 1,25 rockers to the intake on 1 & 3 and then monitor the peak cylinder pressure and compare it to cyl 2 & 4
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