Excuse me but I dont believe 40mm webers & those figures add up even with ethanol
nitriding and snail sidetracking comments aside the revs required to get those figures
from 40mm carbs is close to 10k rpm for most 1.3-1.5 bike engines with much squarer
and suitable bore stroke ratios.

Sure development always keeps moving forward but when you are limited to A series
bore sizes, valve, ports and 2 valves Im sure Nissan reached its pinnacle.
The methanol E series heads you could compare to late Alfa & fiat heads and
Euros have only cracked 120hp per litre with quadruple the effort vs A series.


If A series were developed to be making close to ZX14r hp per litre then
people would be using them for 7k than 10k for a factory busa or kwacka donk.

Honda D15 all motors built by some of the best Honda engineers and tuners still
only manage 130hp at the front wheels with 48mm inlets and some of the best 16v
chambers available for any engine and 79mm sleeved bores.

I agree with Benny and also with D.

My datto alcohol A14 was dynoed at 177 hp @ 9200 rpm and 123 at the rear.And this is 30 yrs ago

So I agree with Benny, that 120+ is very achievable and also he lost 50+ hp and technology has gained in the last 30 -40 yrs

I agree with D , that no way I can see with 40,s or at 7000 rpm

I guess it pays to read closely before passing judgement. At no point did I say 7K RPM. What I have written is a $7K cost to build the engine. I have my doubts about A-series engines producing power at 10,000 RPM, Maybe overun RPM but certainly not producing power.

Peak power from memory on my engine was at 8450 RPM, than fell off from there. As for 40 DCOE 2 Weber with 35mm choke tubes, 45DCOE would have little to no massive advantage. Higher top end maybe at the consequence of bottom end. The irony of all this shoot from the hip chit chat about peak power, is that I am more interested in the torque the engine produces and how consistent the torque delivery is.

I will see if I can find the dyno sheet.

This topic had me dig out my dyno sheets.

First I should have mentioned that the power figures I mentioned on D-Sports Racers where cars equipped with flat slide carbs.

Now on my motor it makes 99whp at 6800 rpm at carries that to 8200 rpm. Starting at 6700 rpm it starts dropping off. At 6500 it's down to 95, then by 6000 it's down to 90, 5600 it's down to almost 80. So in the course of 2600 rpm it's pretty much dropped 20hp. If I had a wazoo gearbox that only dropped this would not be an issue.

Sorry Nick I ment 7k aud is not enough for that hp or with 40s but
I guess it all doesnt really matter if you have the hp and its not
put to use to bring a smile to your face or a sigh to your opponent.
I see RT doing the latter to opposition but with less hp.

I understand why a engine losses 33% from the front to the rear wheels, but why does a engines hp curve drop but keeps reeving ?? example ... Why say a cam revs to 10K when it only makes power to say 8500 rpm ??I say that I cant feel it in a car but on my GSXR you can feel it slowing down. It red lines at 14000rpm but just above 12000rpm it stops pulling.

I remember the owner of Jefferson Ford in Moorabin in early 90,s raced a old Cortina , the one with the fins on the back. He was playing with Roller Cranks and said he got a extra 25 hp from his 1600. But also said he,d only get a few laps before they,d spit it... Has anyone developed that since ??

Now Im worried about my cam . Its a Wade 1009A10 and I cant remember the rev range. I think its 8 K and will it pull to 7 K ??

Wade Cams #1009a 320 degrees, lift .464. lobe separation 106 degrees
Needs springs, carbs
suit speedway

They didn't list rev range, but their next profile (326 degrees) was listed as 4000-7500, and their 297/296 degree profile was 4000-7000

Quote:The HP drops when overrevved because the cam is tuned for a certain RPM range. That means the air charge is started (intake valve opens) before the piston is at Top Dead Center in order to give the slug of air time to start moving. By the time the air gets moving the piston is starting to move down

Now when you overrev it, there is no longer enough lead time to draw in a full charge, so HP drops. It's all in the timing. The stock 6000 RPM cam has this timing:

Intake opens at: 14 degrees BTDC
Intake closes at: 54 degrees ABDC


The 6400 RPM cam (GX cam) opens the valve even sooner (6 degrees earlier)