165HP I6 VS 130HP I4
 

I've been doing some research here lately regarding swapping the older straight 6's rated at 165HP crank over to the newer 3.0L 130HP at the prop. Has anybody here done this swap since many V's came with the straight 6 at 165HP? Comments on it?

I've got a project in mind but it is barring the answers to this question first.

Re: 165HP I6 VS 130HP I4
 

the 165 has a ton more power, their s no replacement, for cubic displacement( well maybe a blower)

Re: 165HP I6 VS 130HP I4
 

It would be going in a twin application where weight is a concern. I know I've read where others have made the swap with good results. But I'm of the there's no replacement for displacement thinking as well, but better economy is the name of the game these days. Just trying to get some input before I commit to anything(plus get the SEARAY done).

Re: 165HP I6 VS 130HP I4
 

the straight 6 would be better than the V6 as Spare said. much more HP and tons more torque.

Re: 165HP I6 VS 130HP I4
 

Plus it's cheaper. I tho't 'bout a V6 package but, my wrench said the straight 6 was a beeter motor. If I wanted more power to go with a 5.7

Re: 165HP I6 VS 130HP I4
 

The 130HP I'm considering is a an inline 4, not a V-6. I'm trying to talk myself(and my wallet) into buying a 26 BERTRAM FLYBRIDGE. They origanally came with the 250 straight 6 @165HP, but many have converted to the straight 4 @130HP and reported no loss and a couple have reported gains in top speed. Just trying to get a different perspective on it since many V-20's came with a single 165HP straight 6.

Here's a pic of one of em I'm considering.
http://i162.photobucket.com/albums/t...726BERTRAM.jpg
I love the lines of these smaller BERTRAM's, and the 24 degrees of deadrise helps.

Re: 165HP I6 VS 130HP I4
 

Thats a awsome looking boat!!!!!!!!!!! I got wood!!!

I know you don't want to hear it, but a twin bracket and twin 150's would be perfect!!

I just have a bad taste for I/O's cause I got bit from 25 year motor, that had everything that could go wong, go wrong!!

But the stright chevy 250's were solid motors!!

Good luck!! I buy that thing just to make my yard look better!! ;D

Re: 165HP I6 VS 130HP I4
 

that 26 bertram is an incredible boat, one Of my custoemrs has one with twin 4.3 MPI's, it runs close to 60, The express is my first choice of an offshore boat. Cummins Mercruisers' r&d shop is here in Charleston, they just repowerd a 26 with twin 150 HP diesels, Capt said it runs great and sips fuel. The best set up I've seen on one of those boats was a guy in a Yamaha class one year, he had a 26 express, he converted it to a center console with a small tower, put a bracket on it and ran a single 225 Opti, boat would run high 40's before he painted the bottom(lost 4 mph), still cruises at 30 thru just about anything. I called BS on his speed, but after researching it, on this web site

http://ccridlin.home.mindspring.com/

they had an original boat house bulliten from Mercury where one of the express' was tested with twin 150(135 at the prop) outboards, got close to 60 mph, you figure in that those motors weighed in over 350 each for combined out put of 270 hp, figure the single opti 225 makes close to 240 hp and weighs 400, it starts to make sense. I don't think the flybridge will perform this well, but its something to think about. If i were going to do it, first choice would be Volvo d3 with the composite drive, d4's with the dpr drive, but either one would be expensive. Probably the most economical way to go would be a pair of 140(or 175) fourstroke Zukis on a bracket. Those older Mercruisers can be a money pit if they stay in the water( its what I make a living on)

Re: 165HP I6 VS 130HP I4
 

This one here that I am looking at was repowered in 99 with the 165HP 4 cylinder 3.7L engines as well as new ALPHA drives. He's wanting low 30's though. I personally would love to do a repower, but my moneys getting tight with all of my other projects going on right now. I gotta get my SEARAY done first and get back on the plus side with it.

Here's a link to another FORUM regarding that 26 MOPPIE repower.
http://www.simplifying.net/plugins/B...ML/001395.html

Re: 165HP I6 VS 130HP I4
 

those 3.7 l engines have a bad reputation, but I've allways liked them, the only problem with repowering them is V6's will have to moved futher apart, whic would require glassing up the transom and cutting new holes, the 3.0 is about the only option unless you want to spend the bucks on diesels or outboards

Re: 165HP I6 VS 130HP I4
 

They say the 3.0L will push them to mid 30's top end, and I've found new 3.0L's for around $7K each(complete assemblys). Would love to get one and do a VOLVO D3 conversion though. 190HP diesels should put it in the 40 knot range top end with a hull that can take 3 footers @ 25 knots and keep on goin. Would be nice.

Re: 165HP I6 VS 130HP I4
 

Spare
I'm curious, since I own one but have not had trouble with it, why the bad rep on 3.7 l. What kind of problems do they have?

Rick

Re: 165HP I6 VS 130HP I4
 

there were a lot of issues with them, but most were fixable and easier for mechanics to blame the engine rather than figure it out.

Rough idle: its a big honking 4 cylinder, what do you expect? Actually it can be smoothed out with the right tuning and posible carb change( the mercrab only had one idle mixture screw for both barrels)

Charging system: yes its expensive, they gave problems because the regulator that mercruiser used created a lot of heat by running the excess voltage to ground, if you have to replace the regulator, use the rapair regulator, its a true on/off type regulator that doesn't create as much heat, but if you really have charging problems( and if you have the room) put the altenator conversion on it

Hard to start/flooding problems: most of this can be attributed to the Mercarb( made by Nikki in Japan), its a cheap copy of a Rochester 2BBL, the early mercarbs were calibrated use Japanese fuel blends(they offered a water cooled fuel linie to help with vapor locking), later versions were better but still were not as good as a Rochester, I converted a Rochester off of an old 888 Mercruiser to work on a friends 3.7, it cranked easier, idled smoother, never heat soaked(thought about putting the water cooled fuel line on it but didn't need it), the engine ran better all the way throught he range, never checked fuel consumption( i doubt it was much difference), the 4BBl Rochester was still the prefered set up(488/485/190)

Cooling system problems: early versions had a 3" heat exchanger, the later 4" was much better

Elbow/riser gaskets: when they changed to the aluminum manifold and cast iron riser, the gaskets would not seal, allowing antifreeze to leak into cyl #4, had a lot of these sent back to Mercruiser under warranty, they updated teh gasket to a better material, haven't had any problem after that, the risers do need to be replaced often if used in salt

Parts are hard to find, and expensive: no arguiing this one, a lot of stuff on this engine were Mercruiser only, I've replaced the pistons with 460 Ford with good luck( they do rattle a little because there is no pin offset as needed in an inline engine), never found a bearing cross over, gaskets are now available aftermarket

Camshaft seals leaking: ever had antifreeze leaking out the bottom front of the engine? its coming out of the weep hole, its not that bad of a job to replace the seals, but sometiimes the cam seal surface is worn, requiring a speedy sleave, seen lots of people plug up the weep hole and didn't worry about it till they got antifreeze in the oil

All this being said, i still liked these engines, my old roommate had a 3.7 in a 17 Stingray, we got that boat running 53 on radar, not bad for a 4cyl, we hurt a lot of peoples feelings with V6's and some V8's. I highly recomend replaceing the points with an electronic conversion, and setting the timing back to 5 degrees( (an early service bullitin).

Any one got an old 3.7 laying around they don't want? My old roommate( sold his original Stingray years ago) has found another Stingray to rebuild, its got a 3.0 in it, he's missing that power of the 3.7, would love to find a 180-190 hp version

Re: 165HP I6 VS 130HP I4
 

Hey man, that link is great. I really am in love with that 26 and what the guy did to it. Check out the folding arch. Gotta build my boat shed to fit one of the Bertram 26's one day ;D That 24 degrees at the transom is a thing of beauty!
http://ccridlin.home.mindspring.com/..._fold_ptlg.JPG

Re: 165HP I6 VS 130HP I4
 

Spare, thanks for the good info. So is the difference between my 165hp and the 190hp the carb? Also what would max RPM on this motor be?

Re: 165HP I6 VS 130HP I4
 

the carb, oil cooler and lines, flame arrestor,fuel line, you may have to change the valve cover to allow the throttle cable to come from the correct direction( the valve cover has a small anchor point for the throttle cable) or you can modify one to work, i checked on every thing else (we were going to change out my old roomates 3.7 to a 4BBL and I cehcked all the part numbers). The Mercruiser replacement long block carried the same part number for each engine, even listed the same cam shaft. The only other thing I would recomend(especially if you're a hot rodder) is to upgrade the rocker arm system to a roller or at least roller tip type rockers, the stock ford rockers suck, anything for a 429/460(Lima series) will bolt up, you may have to use an adjustable stud set up to achieve proper lash, but knowing how inaccurate the stock rockers were, its worth investigating. Check with some local Ford car guys, someone may have half a set of rollers laying around

Re: 165HP I6 VS 130HP I4
 

Hey Spare,

One more question. What RPM should I be looking for at WOT?

Rick

Re: 165HP I6 VS 130HP I4
 

i think factory is 4200 to 4600, the stock valve train doesn't like more than that. We were turning that 165 4800-5000 in that Stingray, every once in a while we stuck a pushrod thru the rocker. Years ago there was a guy around Atlanta that was running a 3.7 in a drag car( econo modified dragster), he was runnig an aluminum aftermarket head, came up with his own cam drive( went to gear drive from chain) and ground his own cams, heard he was turning it 9000 rpm!

Re: 165HP I6 VS 130HP I4
 

I had the 3.7 190hp. Also know as the 470. The motor is decent but they did not have alternators and the cooling systems is expense and know to have problems. They had problems with the front seal leaking (mine did not)
I still have a new heat exchanger in the garage. close to $300.
Stay far away from these engines they are good when running right and pretty effeicent but repairs aren't cheap.

If you buy a bertram do it right and put in a diesel. They have conversion where you can drop a truck diesel into your boat.

Re: 165HP I6 VS 130HP I4
 

If I can afford one I'll go this route with it. Light weight and plenty of gusto. 150 HP set up for an ALPHA 1(I would rather have BRAVOS with a diesel)
http://www.cmdmarine.com/graphics/QSD2.0.jpg
They sure look sweet in a 26 BERTRAM
http://i8.photobucket.com/albums/a43...7/PICT1121.jpg
Or this one. 190 HP VOLVO PENTA D3 duo-prop sterndrive.
http://www.volvo.com/NR/rdonlyres/4C...22_D3C_DPS.jpg

Re: 165HP I6 VS 130HP I4
 

So did you get this boat??

Re: 165HP I6 VS 130HP I4
 

Just dreaming at the moment. I have the money, but to many projects right now.