Amazon with B30

Post by **Fuse** » 26 Dec 2007 07:11 pm

This is insane. What the hell have they fed to that B30, in the vid it tops out 11krpm meter..

http://www.youtube.com/watch?v=LkpyzLDA1J4
http://www.garaget.org/?car=74077

Post by **Tourinki** » 26 Dec 2007 11:03 pm

I watched this earlier and it started bothering me how that engine can rev so high. And suddenly some kind explanation came to my head. Once my uncle told me about his carb-engined 2,8 liter Granada. Apparently it can rev to about 9000rpm (if i remember corretly) And he said also that same kind of car and same kind of engine with fuel-injection. Revs are limited to ~7000 rpm (again i might remember this incorrectly) I asked why there is such big difference between two fuelling and ignition systems. Answer was that in the carbed engines distributor there isn't rev limiter. And that engine will rev and rev until it doesn't get enough fuel or it breaks down.
So maybe here is same kind of situation

Post by **kaos** » 26 Dec 2007 11:17 pm

or its got a really high rev cam and engine work in it.

Post by **SteveP** » 27 Dec 2007 12:38 am

kaos wrote:or its got a really high rev cam and engine work in it.

y0

Post by **Jason B** » 27 Dec 2007 02:10 pm

lol, that sentence was a bit interesting wasn't it.

To make an engine rev that high usually takes a LOT more work than just a high rev cam and some engine work, everything comes into play e.g. rod stretch and correct matched valve setups otherwise a piston would likely reach out and kiss a valve long before 11Krpm possibly even on a non-interference engine.

Still cool though!

Post by **Frits** » 27 Dec 2007 02:22 pm

Revving is what kills a engine. I build a 1.6 Zetec for a rallypuma. Revvs till 9200 rpm. Almost everything has to be changed. I can't explain it in english very good. But it are the acceleration forces what damage everything.

Only when you start building a high revving engine yourself, you'll know what it takes to reach the 9000 rpm.

Post by **classicswede** » 29 Dec 2007 02:24 pm

I'm not that keen on chopped amazons but I do like the 240 door handles.

The B30 is an odd choice but a nice one. It is the carbs that allow it to rev so high and also very stiff valve springs to stop valve bounce at high rpm.

With FI normaly engines are limited to about 6500-7000 rpm so the injectors do not max out. You can make a single injector work to higher revs but it needs to be very high flowing and capable of opening for very short times for idel.

Mazda use 3 injectors per cylinder on the rotary engine to allow it to rev over 10,000 rpm! 1 injector for upto about 3000 then a second for upto about 6000 and the 3rd also comes in for the top end.

Post by **foggyjames** » 31 Dec 2007 01:46 am

I can't help but think that the head is going to be a major restriction once you're up at nearly 12krpm. The heads are often fundmentally reworked (i.e. ports doubled in size with extra metal grafted on, etc) even for operation in the 8krpm region. Still....Amazon + B30 = droooool

The engineering challenges associated with making an old boat engine hang together at double the original redline are not insignificant. Weight and strength of the internals become very significant. I know some builders of bike engines tend to go for lighter, rather than stronger, components (no H-beam rods, for example)...so I'd be interested to see what has gone into this beasty!

cheers

James

Post by **classicswede** » 31 Dec 2007 11:35 am

The B30 bottom end is good for high revs with only balancing.

The top end is where the work is but even then you do not have to do a great deal to make it rev that high. The main thing is stiffer valve springs to stop valve bounce. Its not hard to make an engine do that but more care has to taken to keep it relighable.

Do not ever take a B30 to high revs when its cold - they do not like it.