B20/B30 - Noticeable benefits of bigger exhaust valves/double valve springs?

ab1 · 2017-04-13T09:35:40+00:00

Maybe if you're planning on going higher than stock rpm limits. Also, any other mods to intake or exhaust or is it mostly stock?

Philia_Bear

Not that i know enough about b30 builds...
But will 50% didplacement and cylinders mean 50% more power?

ab1

blondejay;105227 wrote

how tf do you manage 130rwkw on a b20

deleted_user_160

With good engine management, suitable cams and what not

iceton1975

Scandix do headers for B30 they about $500

Spac

Nobody is making 130kW ATW from a NA B20 using a ported iron head. Its a fantasy, possibly one perpetuated by overseas hub dynos.
Show me a NA B20 that makes 110kW on an Aussie rolling road dyno, and I'll show you where someone has very carefully spent ~$20k.

Philia, a B30 has better port design than a B20. Don't know how relevant that is for a serious build, but it is probably enough make a B30's output actually be close to 1.5x that of a comparable B20.

Vee_Que

blondejay;105227 wrote130rwkw from a b20 on ms1 with quad itb

Or people have made 130whp with a djet manifold with megasquirt. So to do so with a b30 us possible, particularly as his head has been ported by a professional already. But because it's an otherwise stock build, it will lose hp, but hopefully not be any less drive able.

Fwiw, the 144 and 122 on this chart are both race motors, and they fiddled with the carbs etc that day to get the power up. So 105rwkws from a race engine on avgas...

iceton1975

My 164 B30 carby engine with SUs has K cam profile and injection head fitted and goes very well, parts came from VPAUTOPARTS SWEDEN

Major Ledfoot

Vee_Que;105269 wrote Fwiw, the 144 and 122 on this chart are both race motors, and they fiddled with the carbs etc that day to get the power up. So 105rwkws from a race engine on avgas...

If we're directly comparing dyno numbers, this chart is really the only way to do it. Nobody knows for certain how another shop calibrates (or don't calibrate) their dyno, so using the one shop with the same cars is the only way to do accurate comparisons.

ab1

how well is very well @iceton1975

iceton1975

come and drive it

tclarkson142

I had a 142 with a head with double valve springs and larger exhaust valves. This car was - and still is a 1970 - and therefore would have had smaller valves initially. The ones in this head were not stock Volvo valves as the stems were a lot thicker. It was suggested that they may have come from a Holden of some sort. The work on this had been done in Vic somewhere as this is where the car was originally registered. It also had widened steel rims and rally tyres when I first got it. The other unusual thing about it was the Mota-Lita steering wheel and GT(?) dash (speedo, tacho and 4 other dials). Someone suggested it was one of a batch of early 142's which had been specked up to the same extent.
The whole car has been done up beautifully by the current owner with o'd gearbox and aircon. It has also been lowered slightly and corners on rails.

robv

There is a lot of horse power to be gained in the exhaust. A standard exhaust or factory r sport exhaust is limited to about 145hp on a b20. Bigger valves give more horse power but are prone to cracking between valves. Longer inlet runners also improve power especially when you start to rev them. Standard pushrods need to be replaced as they bend.

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