Hi Marc & Scott

Thanks for all your help so far, but I need to ask for more.

My current speed I am getting is 89,9 km/p.h, but would like to reach 90 and above.

My port timing is exhaust 175, intake 150, squish 1mm, piston has been lightened as per your advice to the gram.

Am using a South African designed Cat (will try to send photos).
Using Top Secret hardware & ABC 2714 Prop.

PLEASE HELP - how can I increase my speed ???

Regards

Mark

Ex at 178/180... intake at 155

prop boat so rpm is in the high 16's low 17 K range

Test test test :?

Hi Scott

Thank's for the quick reply, have posted a few pic's on the gallery.

Regards

Mark:drinks:

Hi Scott

Once again many thank's for the info.I ported my motor as you said and managed to get too 92.4km per hour.

1 How much can the fly wheel be lightend.

2 If the crank is modified as you suggest(turbo) will there be a vast improvement.

3 I use a return to centre pipe

Sory Scott

Dont know what I did, but that is what my pipe looks like.

Would an adjustable pipe be better?

I have taken a standard 644 Walbro filled the front with plastic steel and bored it out as explained in(modifying a carb)to get rid of all the bumps etc. It seems to work well.

Regards

Mark

Never found a WTC style pipe able to get short enough.
You will indeed find more RPM and power with a adjustable pipe able to go shorter than the WTC you now are using.

:clapping: glad you made your 90 + ..... now keep going for more !!

* The turbo crank mod is not for a HP gain, just helps engine breath a bit better without having fuel pooling while at lower rpm.
If not comfortable doing it ... don't

Wrap to center pipes can work if designed right. here's one I have that is tapered from shortly after the manifold. It has had my sport hydro up to 125 kph with the previous owner, I've personally had it to 117 kph. I'll have to get a better picture, you can't quite see it well enough.

Most wrap to center pipes can't be adjusted short enough as Scott says. the one I have is no longer in production due to the high cost of manufacturing them. If I ever saw another one for sale I'd snap it up in a second.

The newer style QD WTC Hotpipes will tune properly. Most old style as Scott mentionned, will not tune for optimal performance.

Ah forgot to say ... DON'T mess with the flywheel, lightening only will have engine rev faster but will loose torque in the corners.
Also weakens it and could lead to catastrophic failure.

* If you do have the miens tho, a tad bid of balance adjustment can smooth things out a bit more :dance2:

Thank's guys

Scott. I have allready lightend the flywheel faces and not the OD.
I also took out the choke when modding the carb(644) and still have a primer bulb and a big thumb.

Still can't load photos on the gallery (too old) will get my son to help.