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F-2 Speedy 10-08-2020 04:55 PM


Originally Posted by JohanSweden (Post 4760820)
Thanks. Must love carb engines - as you say, easy to work on.

Whats your thoughts about the Merc 540 Bulldog with procharger, instead of HP500, I just mentioned thats for sale?

that will be a drive breaker for sure, unless its a SCX

SR24Dave 10-08-2020 05:00 PM

Has anyone taken a SCX and had it REM polished and cyro treated?
Or do they come that way?
just curious.

SR24Dave 10-08-2020 05:01 PM

My thought is that if they are that good to start, wouldn't this process make them even better?

Griff 10-08-2020 09:07 PM


Originally Posted by JohanSweden (Post 4760820)
Thanks. Must love carb engines - as you say, easy to work on.

Whats your thoughts about the Merc 540 Bulldog with procharger, instead of HP500, I just mentioned thats for sale?

Will need high octane fuel. Less longevity, more potential for failures and will push your drive beyond its limits.

JohanSweden 10-09-2020 12:14 AM


Originally Posted by F-2 Speedy (Post 4760830)
that will be a drive breaker for sure, unless its a SCX


Originally Posted by Griff (Post 4760871)
Will need high octane fuel. Less longevity, more potential for failures and will push your drive beyond its limits.

Thanks for your advice guys, maybe the XR will handle it but eventually not the X upper.. hmm. The 540 has ben running with XR setup in many years without drive failure.
Maybe he was lucky.

Here in Sweden we have 95 octane gas as standard, and also 98 high octane so that eint no problem if running with the 98 octane.

JohanSweden 10-16-2020 02:09 PM

Is there any calculation on what speed I can expect with procharged 540 bulldog 770hp?

Now I have top speed at 52 mph @ 4750rpm with my 425hp merc 496.

Someone said like 25-30hp is like 1-2mph gain.
Would be nice to get some higher cruising speed.

sutphen 30 10-16-2020 07:03 PM


Originally Posted by JohanSweden (Post 4761932)
Is there any calculation on what speed I can expect with procharged 540 bulldog 770hp?

Now I have top speed at 52 mph @ 4750rpm with my 425hp merc 496.

Someone said like 25-30hp is like 1-2mph gain.
Would be nice to get some higher cruising speed.

if you have a bravo,,top speed will be what ever the tow boat has.:D

Griff 10-17-2020 01:29 AM


Originally Posted by JohanSweden (Post 4760887)
Thanks for your advice guys, maybe the XR will handle it but eventually not the X upper.. hmm. The 540 has ben running with XR setup in many years without drive failure.
Maybe he was lucky.

Here in Sweden we have 95 octane gas as standard, and also 98 high octane so that eint no problem if running with the 98 octane.

Keep in mind that European octane ratings are calculated differently from American octane ratings.
95 EU = 90 US and 98 EU = 93 US

Griff 10-17-2020 01:33 AM


Originally Posted by JohanSweden (Post 4761932)
Is there any calculation on what speed I can expect with procharged 540 bulldog 770hp?

Now I have top speed at 52 mph @ 4750rpm with my 425hp merc 496.

Someone said like 25-30hp is like 1-2mph gain.
Would be nice to get some higher cruising speed.

Approx 15hp for every 1 mph gain for where you are at, but its not linear. If you started at 75mph, it might take 25 hp to gain 1mph

JohanSweden 10-17-2020 02:50 AM


Originally Posted by Griff (Post 4761989)
Keep in mind that European octane ratings are calculated differently from American octane ratings.
95 EU = 90 US and 98 EU = 93 US

Every day I learn something new, thank you Griff. Didnt know that :)


Originally Posted by Griff (Post 4761990)
Approx 15hp for every 1 mph gain for where you are at, but its not linear. If you started at 75mph, it might take 25 hp to gain 1mph

So approx 25 mph gain from 425hp to 770hp?


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