Crazy ass 40hp engines? F-Vee motors and the like

[Wally]

What sort of revs were you doing with that 40hp?

About max. 6500 rpm iirc.
They were also shotpeened, rebuild and balanced. Not a half job, but now you heard its just a dyno queen, so that doesn't prove anything still huh
Like I already said before, I agree they are a weak rod, that doesn't mean you can't improve them. They also just handle tiny 77mm (light) pistons.

[petew]

Yeah, fair enough. Did the dual port 1300 heads bolt straight up? And I assume you were running HEAPS of fuel into them to stop detonation?

[Wally]

Yeah, fair enough. Did the dual port 1300 heads bolt straight up? And I assume you were running HEAPS of fuel into them to stop detonation?

Yes to the bolt-on, NO to the HEAPS of fuel. I ran the same optimal AFR as I do on my big T4 engine.
I do use water-injection and good air-air intercooling. Again, same as I do on my T4 turbo engine.

Good tuning = good tuning = good tuning.

Just saying that because its a smaller/cheaper engine that doesn;t mean your regular tuning principles go out the door.
Maybe it even work more like the other way around: the weaker/cheaper the base engine, the more important good tuning and keeping the engine and intake charge cool, really is... then again, thats always important.

[petew]

Good point. Could you tell me more about the headwork you did to the dualports and your water injection setup? Is the Water inject electronically controlled or just a vaccuum feed thing?

[Wally]

The 1300 DP heads were left basically stock, just a little mild porting next to the valve guides, which were replaced and a (very) good valve seat job (beyond 3-angle, superfinished). Original valve sizes (35,5x32), stainless.

WI is a system from Aquamist (2d), which is electronically contolled indeed and sprays a set percentage of the fuel injection time throughout the map at high pressure. Its also a 50-50 mix of destilled water and pure methanol.

The engine suffered a bad temp sensor I found out later as it didn;t ran as I knew it could. Goal was 200 hp. Maybe next time, maybe with a 36hp, we'll see
The point was also more to see if the stock parts (weak 64mm crank and rods plus cast mahle pistons) were up to it. That part was succesfull anyways

[petew]

cool.

[LIFE IN THE LOW LANE]

My uncle builds formula vee race cars and the best 1200cc he built made 67.9hp atw. D series case single port heads, controlled cc on heads and valves, stock manifold with 28pict carb. It would rev easy to 6800rpm and if pushed it would run to just over 7100rpm. Stopped making power at 6600rpm!!

He is now building 1600 dual ports for formula vee. Heads are basically stock with stock manifold with 34 pict carb with all the usual control ingredients of formula vee(cam grind etc etc) and his best engine so far has made 87hp. 1600 won't rev as hard as the 1200 did but make more torque. At a vw drag meet a few weeks ago he bought 2 cars out to compete in the special class and both cars ran into the 8's!! Fastest was 8.92@ 74mph

[Marc]

Note that the 1300DP heads use the same valve sizes and spacing as 1600DP - they're seriously shrouded with a 77mm bore; in fact, the intake valves will actually hit the ends of the cylinders if opened too far with a 77 or 77.5mm bore...you have to go .040"-over (78mm) just to prevent that, unless you carefully grind away material from the cylinder walls above the top piston ring's reach.
Years ago I ran in a 1300cc restricted circle-track class - even with stock rockers, a cam with respectable lift could push the intakes into the ends of 77mm cylinders if they weren't clearanced after the heads were flycut ~.250" for compression.

[Wally]

Note that the 1300DP heads use the same valve sizes and spacing as 1600DP - they're seriously shrouded with a 77mm bore; in fact, the intake valves will actually hit the ends of the cylinders if opened too far with a 77 or 77.5mm bore...you have to go .040"-over (78mm) just to prevent that, unless you carefully grind away material from the cylinder walls above the top piston ring's reach.

Thats correct, but not specific a 1300DP head 'problem' with the 77mm bore. I.e. the 1200/1300 single port heads have the same valve spacing right?
I/we did indeed clearence the cylinder bore above the top ring to gain a little unshrouding. Some other 1200 Challengers reduced intake valve sizing to 34.5mm and/or in addition to gain some extra unshrouding properties.
It was a fun contest and I learned a lot about 40hp engines

[andy198712]

Does sound like fun!
Reducing valve sizes sounds good as you can use the same valve and seat, but there is normally a 1mm or so over hang isn't there? Does that make sense?

[Marc]

...not specific a 1300DP head 'problem' with the 77mm bore. I.e. the 1200/1300 single port heads have the same valve spacing right?...

The same issue exists with any head with a 35mm intake valve. Obviously it's not a problem with 32mm 1200 intakes, or the 33mm intakes used on 1300SP and 1600 L-Jet heads.

[Wally]

Yep, the single port heads also have smaller valves.
Cheers,
Walter