Overpowered versus Light
Posted: Tue Oct 04, 2011 6:19 am
Hi Georg
I lost somewhere my password to Volga forum and therefore I catch you beyond the forum - on Niveko mail address.
I have a 1982 Volga boat – strictly the same model as yours (narrow body with zmz53 and v-drive). Unfortunately my Gaz53 takes water to the engine oil and it can be both something very minor as good as very, very serious damage. It will come clear Saturday.
In case of the second scenario I consider general change – replacing the old engine with Chevy 350 small block (I have here a specialist to get and do such engine at reasonable price).
Considering the change, I am writing you - as a person associated with marine gearboxes business – as far as I remember your company represents ZF Marine.
And here my question comes:
DO YOU HAVE AN IDEA, IF THE ZF V63 IV (RECOMMENDED MANY TIMES AS AN ALTERNATIVE TO THE ORIGINAL VOLGA V-DRIVE) WILL FIT THE 310HP CHEVY 350, OR IT IS TOO WEAK AND THAT ENGINE REQUIRES A STRONGER V-DRIVE?
There are no cases like this on the forum - Micker in his Danish “Mighty Hydro” uses a heavy duty Crusader v-drive, but it works with 7,8ltr Big Block above 400HP, and Jim Pedra uses Chevy350 but with Z-drive …)
WOULD IT GO WITH ZF V63?
Regards
Gil
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Dear Tomasz,
Your question is not unjustified. The counterquestion: Do you use the same propeller? The original propeller was built to transmit 90 HP into the water.
The gearbox is an intermediate element which transfers the power. I believe, that unless you do not buy a different propeller requiring more power from an engine, you do not increase the torque on the driveline. You obviously only transfer 90 HP ( of 250 or 400 HP ) to a propeller.
You should be aware, that once having a problem with a rope or wire coming into the propeller clogging it you will then see what happens to that gearbox!
You should not unnecessarily overpower a Volga. The foils and the body are made for 36 knots and you reportedly encounter serious strength problems over 40 kn.
The shape of the aft propeller strut is not made for a bigger propeller and thus needs changes.
My proposed configuration (light engine 250 kg, 170 HP + ZF 63IV approx 60 kg) should give sense as you save 100 – 200 kgs on the boat. The chevy 350 small block is cast iron and weighs probably same like the gaz53, if not more. The heavier gearbox (crusader, ZF 80IV or else ) would weigh probably same or +/- 30 kgs of the original configuration. Now I ask: What for? For running the same small propeller of the Volga 70?
The answer is on the hand. It would be easily understood when taking in consideration that small Lotus Cars were winning many races, but overpowered Mustangs or Corvettes could never beat them in performance. Having a boat with 5 – 15% less weight means much more than having more power you will not be able to transfer + with all its weight.
Chosing big or small US V8s is just a matter of sound and will be a cheap configuration but not for best performance. Dinko uses a 120 HP 2nd hand old Mercedes diesel engine and his Volga performs wonderful.
Best regards,
Georg
P.S. We do not sell ZF gearboxes anymore.
I lost somewhere my password to Volga forum and therefore I catch you beyond the forum - on Niveko mail address.
I have a 1982 Volga boat – strictly the same model as yours (narrow body with zmz53 and v-drive). Unfortunately my Gaz53 takes water to the engine oil and it can be both something very minor as good as very, very serious damage. It will come clear Saturday.
In case of the second scenario I consider general change – replacing the old engine with Chevy 350 small block (I have here a specialist to get and do such engine at reasonable price).
Considering the change, I am writing you - as a person associated with marine gearboxes business – as far as I remember your company represents ZF Marine.
And here my question comes:
DO YOU HAVE AN IDEA, IF THE ZF V63 IV (RECOMMENDED MANY TIMES AS AN ALTERNATIVE TO THE ORIGINAL VOLGA V-DRIVE) WILL FIT THE 310HP CHEVY 350, OR IT IS TOO WEAK AND THAT ENGINE REQUIRES A STRONGER V-DRIVE?
There are no cases like this on the forum - Micker in his Danish “Mighty Hydro” uses a heavy duty Crusader v-drive, but it works with 7,8ltr Big Block above 400HP, and Jim Pedra uses Chevy350 but with Z-drive …)
WOULD IT GO WITH ZF V63?
Regards
Gil
-----
Dear Tomasz,
Your question is not unjustified. The counterquestion: Do you use the same propeller? The original propeller was built to transmit 90 HP into the water.
The gearbox is an intermediate element which transfers the power. I believe, that unless you do not buy a different propeller requiring more power from an engine, you do not increase the torque on the driveline. You obviously only transfer 90 HP ( of 250 or 400 HP ) to a propeller.
You should be aware, that once having a problem with a rope or wire coming into the propeller clogging it you will then see what happens to that gearbox!
You should not unnecessarily overpower a Volga. The foils and the body are made for 36 knots and you reportedly encounter serious strength problems over 40 kn.
The shape of the aft propeller strut is not made for a bigger propeller and thus needs changes.
My proposed configuration (light engine 250 kg, 170 HP + ZF 63IV approx 60 kg) should give sense as you save 100 – 200 kgs on the boat. The chevy 350 small block is cast iron and weighs probably same like the gaz53, if not more. The heavier gearbox (crusader, ZF 80IV or else ) would weigh probably same or +/- 30 kgs of the original configuration. Now I ask: What for? For running the same small propeller of the Volga 70?
The answer is on the hand. It would be easily understood when taking in consideration that small Lotus Cars were winning many races, but overpowered Mustangs or Corvettes could never beat them in performance. Having a boat with 5 – 15% less weight means much more than having more power you will not be able to transfer + with all its weight.
Chosing big or small US V8s is just a matter of sound and will be a cheap configuration but not for best performance. Dinko uses a 120 HP 2nd hand old Mercedes diesel engine and his Volga performs wonderful.
Best regards,
Georg
P.S. We do not sell ZF gearboxes anymore.