1977 Trojan 318 engine performance

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Svend
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1977 Trojan 318 engine performance

Post by Svend » Sun Jul 21, 2019 10:45 am

1977 Trojan 318 engine performance issues?!

I have twin 318's, electronic ignition, one helm

my best performance is 3100 RPM and 29 MPH
my props are factory size, and specs...

I seem to read a lot of people getting 4000 RPM, and higher speeds...

so all you engine performance people on here!! what is causing both my engines to perform like this...
they run great, always start, idle at 500 for 4.5 mph... consume normal amount of gas... etc...

all ideas and thoughts welcome was well as top three performance upgrades and benefits ...

thanks!!!

Svend
1977 Trojan F30 Express, With Dual 318's with Electronic Ignition
Raymarine EV 100 Auto Pilot

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prowlersfish
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Re: 1977 Trojan 318 engine performance

Post by prowlersfish » Sun Jul 21, 2019 11:48 am

What size props do you have ? 29 MPH is good 3100 rpm is low . Also 4.5 mph seems high for 500 rpm . I don't remeber my F30 being that fast at idle speed . Are you sure your tachs are right ?
TROJAN F36 Conv.
6BTA Cummins diesels
Life is to short for a ugly boat :D
2009 TROJAN RENDEZVOUS
Port Kinsale 2010 & 2011. Solomons get together 2011.

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prowlersfish
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Re: 1977 Trojan 318 engine performance

Post by prowlersfish » Sun Jul 21, 2019 1:12 pm

prowlersfish wrote:
Sun Jul 21, 2019 11:48 am

What size props do you have ? 3 or 4 blade ? 29 MPH is good 3100 rpm is low . Also 4.5 mph seems high for 500 rpm . I don't remeber my F30 being that fast at idle speed . Are you sure your tachs are right ?
TROJAN F36 Conv.
6BTA Cummins diesels
Life is to short for a ugly boat :D
2009 TROJAN RENDEZVOUS
Port Kinsale 2010 & 2011. Solomons get together 2011.

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Svend
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Re: 1977 Trojan 318 engine performance

Post by Svend » Mon Jul 22, 2019 11:55 am

Thanks for reply!

the prop has this stamped on it: 14 R 11
and they are 3 blade props

look forward to your thoughts!

Svend
1977 Trojan F30 Express, With Dual 318's with Electronic Ignition
Raymarine EV 100 Auto Pilot

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prowlersfish
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Re: 1977 Trojan 318 engine performance

Post by prowlersfish » Mon Jul 22, 2019 9:06 pm

While that is factory size most will do better with a little less pitch . Our boats start getting a little fatter from day one.

Frist make sure the tachs are right .
TROJAN F36 Conv.
6BTA Cummins diesels
Life is to short for a ugly boat :D
2009 TROJAN RENDEZVOUS
Port Kinsale 2010 & 2011. Solomons get together 2011.

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Paul - SW Ontario
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Re: 1977 Trojan 318 engine performance

Post by Paul - SW Ontario » Tue Jul 23, 2019 8:02 am

prowlersfish wrote:
Mon Jul 22, 2019 9:06 pm
While that is factory size most will do better with a little less pitch . Our boats start getting a little fatter from day one.
100% Correct...

As mine 'fattened up' over my first ten years of ownership, which gradually dropped my performance to 2800 rpm (3000 on a good day)...I went with this suggestion and re-pitched.

Went from the factory 14 R 10...down to 14 R 9

Result, right back to 4000 WOT under load...recovered gusto when powering thru confused water here in Lak Erie.

Not wanting to put the old girl on a diet (the Trojan that is :shock: )....I immediately sent my spare prop to be re-pitched.
1973 Trojan F25.5 - SW, ON.
2012 Triple Axle trailer
1978 C&C Mega 30' Sailboat
2014 Triple Axle trailer
2016 Highfield CL290 BL RIB
2017 20hp Suzuki 4 stroke

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Svend
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Re: 1977 Trojan 318 engine performance

Post by Svend » Tue Jul 23, 2019 8:48 am

great ideas!!

3 blades or 4 ?

what is a good way to test tach's to make sure they are accurate...

thanks!

Svend
1977 Trojan F30 Express, With Dual 318's with Electronic Ignition
Raymarine EV 100 Auto Pilot

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prowlersfish
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Re: 1977 Trojan 318 engine performance

Post by prowlersfish » Tue Jul 23, 2019 1:05 pm

Photo tach to check your tachs . drop a inch and see how it goes ( 2" if going 4 blade ) .
TROJAN F36 Conv.
6BTA Cummins diesels
Life is to short for a ugly boat :D
2009 TROJAN RENDEZVOUS
Port Kinsale 2010 & 2011. Solomons get together 2011.

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Paul - SW Ontario
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Re: 1977 Trojan 318 engine performance

Post by Paul - SW Ontario » Tue Jul 23, 2019 11:26 pm

Mine are three blade NiBrAl props.
1973 Trojan F25.5 - SW, ON.
2012 Triple Axle trailer
1978 C&C Mega 30' Sailboat
2014 Triple Axle trailer
2016 Highfield CL290 BL RIB
2017 20hp Suzuki 4 stroke

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Svend
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Location: Gilford NH
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Re: 1977 Trojan 318 engine performance

Post by Svend » Wed Jul 24, 2019 11:54 am

hi prowlerfish

can you explain Photo tach to check your tachs
I am a newbie on engines

also, would love to hear your thoughts on 3 glad vs 4 blades...
and your thoughts on goals for a cruiser boat with most time spent at low speed cruising, and then wanting to get home quickly sometimes (but never needing a quick start off line for say water skiers)

thanks!
1977 Trojan F30 Express, With Dual 318's with Electronic Ignition
Raymarine EV 100 Auto Pilot

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