Underpowered 88spl upgrades

[big boat little motor]

Hello all,
This is my first post and wanted to bounce a couple of thoughts off of you all with far more wisdom than I. First of all I just purchased a 1997 Lowe Silhouette 19' with a 1989 Johnson 88spl. This boat is rated for a 135 HP motor and with its current set up it is wickedly underpowered. Trying to be cheap given what the economy is like now I think I would like to try to squeeze a few more ponies out of the motor I have. After picking up the parts and service manual it looks like the 89 models for 88 and 110 were the same with the exception of the carbs and heads. Am I wrong in thinking that if I swap those and update to some new reeds should get me close to the 110 hp number? And also are there other years of heads that will give a good bang for the buck as well?

Thanks In Advance

 

[kenmyfam]

Re: Underpowered 88spl upgrades

Welcome to iboats
Reality is to put a bigger motor on. You have a great and saleable motor. Be certain that the set up you have is giving optimum performance before wanting more HP. Loading, trim, motor height, prop etc.

 

[big boat little motor]

Re: Underpowered 88spl upgrades

thanks for the thoughts on that. The prop that came with the boat is an unknown pitch. Where do i go to find a recommendation for what pitch should be on this boat?

 

[Chinewalker]

Re: Underpowered 88spl upgrades

The prop should have the pitch stamped in the hub. Either that or a part number that you could Google for a cross-reference.

As for making more power from the 88 - there is no easy bolt-on, outside of bolting on a bigger motor.

- Scott

 

[emdsapmgr]

Re: Underpowered 88spl upgrades

The heads on that engine are fairly low compression, so any older (1970's-early 80's), tighter heads will make an improvement in performance. The 110 uses larger carbs than the 88. If you change the heads, you will need to flow more fuel, so larger carbs will probably work out ok. Probably not worth the effort to do anything with the bubble back exhaust covers, considering the effort required to install them. You won't see much improvement on low end, but the engine will run better top end. All in all you might gain 300 rpm, which is about one prop size.

 

[tashasdaddy]

Re: Underpowered 88spl upgrades

yes, you are underpowered, the rule of thumb, is to expect decent performance of a hull, 70% of the max hp is required. your boat is rated 135hp, 70% is 94.5hp. the 88 has a good reputation. sell it and upgrade.

 

[iwombat]

Re: Underpowered 88spl upgrades

^^^ agreed sell and upgrade. Usually, the ports are different on the lower HP, but same size blocks. Not certain about yours in particular.