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Author Topic:   HONDA BF135 change to BF150
Perry posted 10-13-2005 10:55 PM ET (US)   Profile for Perry   Send Email to Perry  
According to an article I read in a boating magazine, the only difference between the BF150 and the BF135 is that the BF135 doesn’t have the ground wire hooked up to the VTEC spool valve and doesn't have the ECU mapping to control the variable valve timing.

Do you think it would be possible to hook up the ground wire to the VTEC spool valve and have the ECU re-mapped to control the variable valve timing? I haven't priced a new ECU for a BF150 but I have a feeling it would be very expensive.

LHG posted 10-14-2005 04:18 PM ET (US)     Profile for LHG    
Perry - am I reading between the lines that you could use more "dig" from your Honda 135?

Mercury's 2006 catalog "claims" (accepting that we all know sales brochure claims can't be trusted!) that the supercharged 150 Verado accelerated 0-30 TWICE as fast (in half the time to use their wording) as a convnetionally aspirated Honda 150. They also indicate that it is 15% faster in acceleration than the Yamaha 150, so that indicates the Yamaha has faster acceleration than the Honda also.

It might not be worth the effort and cost to achieve this variable valve timing, as it doesn't seem to do that much.

If what Mercury is saying is true, it sounds like a Verado 150 would be a great power option for a Nantucket, if one wants 4-stroke power instead of DFI Optimax

Peter posted 10-14-2005 06:11 PM ET (US)     Profile for Peter  Send Email to Peter     
LOL....We all know how Merc conducts its testing of competitor motors when making claims for acceleration: put the highest pitch propeller that will keep the competitor's motor just above the low end of the WOT operating range which in the case of the Honda would be 5000 RPM.
LHG posted 10-14-2005 06:15 PM ET (US)     Profile for LHG    
And, like Evinrude, they install a CompProp.
Perry posted 10-15-2005 03:31 AM ET (US)     Profile for Perry  Send Email to Perry     
Larry, yes, I could use a little more "dig" from my BF135. The only complaint I have about this motor is its ability to launch from a dead stop. I have heard that the variable valve timing improves the torque in this part of the powerband and thought if it was doable, why not try to get the VTEC to operate. It's already installed on the motor, it just needs to be hooked up.

I don't put much stock in Mercury's sales brochure or their comparitive testing practices. What I do know is that I have run with an identical Nantucket with a 150 Otimax several times. His boat will out accelerate mine by a couple boat lengths but I overtake him at around 35 MPH and slowly walk away from his boat even though his motor has 15 more HP.

According to Whaler's own performance data, the Verado powered 190 Outrage acclelerates to 30 MPH in 9 seconds. To suggest that a BF150 powered Nantucket/Outrage would take twice as long (18 seconds) as a Verado 150 is ridiculous. The 115 Mercury 4 stroke took less than 15 seconds to reach 30 MPH on the Nantucket. Larry, do you really believe the rubbish that Mercury "claims" in their sales brochure? I've done some performance tests of my own with a digital stop watch and GPS. I know it is far from accurate but my 0 to 30 MPH times range from 8 to 10 seconds which is about the same as the Verado 150.

Riverwhaler posted 10-15-2005 08:28 AM ET (US)     Profile for Riverwhaler  Send Email to Riverwhaler     
Perry don't want to say I told you so experience with the valve timing is that I can definitly feel and hear when it changes, or kicks in. Are you sure thats all that is changed? Some one somewhere has to know what you can do. Every time I see a Honda 135 I say why did they buy it?
I would relish a race between all the 150HP Nantuckets. Especially now that I finally followed your advice on raising the Engine.
jimh posted 10-15-2005 08:57 AM ET (US)     Profile for jimh  Send Email to jimh     
Variable Valve Timing (VVT) or camshaft phasing has a significant effect on engine performance. This technique is being used in a large number of four-stroke engines in automotive applications to enhance performance. It appears the automotive industry trend in gasoline engines is to move toward VVT. Further enhancement will be accomplished through variable valve lift (VVL).

The HONDA outboards use VVT. Their approach to marketing is rather frustrating to me. On your 135-HP engine you have all the mechanical components of the VVT engine, yet none of this is being used. And, as you postulate, apparently all that is stopping it from coming into use is the firmware in the engine control module. The cost to manufacture the 135-HP engine has to be exactly the same as the 150-HP engine--they're the same engine mechanically. The premium price for the 150-HP model must be all profit. Changing the firmware in the engine control module costs the manufacturer nothing, as far as I can tell.

So locked inside the engine control module of your engine is more performance, if you could just reload the firmware. But doing that will be difficult, I expect. If word got out you could turn the 135-HP into a 150-HP with a simple modification, it would upset the pricing differential between the two.

jimh posted 10-15-2005 09:15 AM ET (US)     Profile for jimh  Send Email to jimh     
To learn more about how Variable Valve Timing (VVT) and Variable Valve Lift (VVF) enhance engine performance, read this nicely done tutorial:

davej14 posted 10-15-2005 09:42 AM ET (US)     Profile for davej14  Send Email to davej14     
I've been thinking about this same marketing philosophy. The only reason I can come up with that would make a manufacturer want to "detune" their engine design is that some hulls may not be rated for more than 135 HP. Rather than have a separate engine design specifically for this HP the market can be expanded with the same engine design by doing it in software. This probably makes sense for the manufacturer.
jimh posted 10-15-2005 10:08 AM ET (US)     Profile for jimh  Send Email to jimh     
Dave--a look at the price sheet will test your theory.

What bugs me about the HONDA approach is the lower horsepower engine is carrying around the weight and complexity of the VVT cam system but it never uses it!

Perry posted 10-15-2005 01:22 PM ET (US)     Profile for Perry  Send Email to Perry     
Jim, I can understand your frustration with Honda. I live it every day. The practice of offering different HP models of the same basic outboard motor is something that has being going on for a long time. OMC produced many varients of their V4 by using different carbs, jetting, porting, reeds etc. This cost them little or nothing to produce more HP. It is standard business practice to charge more money for more HP.

Riverwhaler, there are 3500 reasons why I chose the BF135 over the BF150 if you know what I mean. I got my leftover BF135 for $8500 and a new BF150 would have cost me $12000.

Back to the original question. Do you think a certified Honda mechanic could or would re-map the firmware in the ECM to allow the VTEC to operate?

Riverwhaler posted 10-15-2005 06:24 PM ET (US)     Profile for Riverwhaler  Send Email to Riverwhaler     
If it took $3500 to make me perfectly happy with my boat I think it is a good value. I say all this for other people reading this. Don't skimp on the outset you will pay later.
Even later when you sell the boat ( heaven forbid) but it will happen sometime. Sorry Perry to make an example of you....
kglinz posted 10-15-2005 08:15 PM ET (US)     Profile for kglinz  Send Email to kglinz     
The VTEC will not help you with aceleration. It does not "kick in" until 4500 RPM and you are probably well on plane by then. Honda's website will explain how it works.
jimh posted 10-15-2005 10:46 PM ET (US)     Profile for jimh  Send Email to jimh     
Actually the VVT in the VTEC engine does help because it allows the engine to have a different valve timing for low RPM so that it can develop more torque at those speeds and then switch to a different timing at higher RPM so it can develop more horsepower. If it didn't help, why would they do to all the trouble of using it?
Perry posted 10-15-2005 10:59 PM ET (US)     Profile for Perry  Send Email to Perry     
Jim, that is how I understand it works too.

Riverwhaler, I never said I was unhappy with the overall performance of my boat. I just figured that if there were some extra ponies to be had, why not try to harness them.

I drilled vent holes in my prop today and it really helped spool up the prop from a dead stand still. It launches much better now. The Powertech prop I have is double cupped and it really benefited from the 3/8" vent holes.

kglinz posted 10-15-2005 11:01 PM ET (US)     Profile for kglinz  Send Email to kglinz     
If the 135 and the 150 are using the same cam, as Perry thinks, I don't see how it could help the 135 below 4500 RPM. Now if the 135 had a different cam or a different fuel map, it could have a totally different power curve from the 150. The VTEC does exactly what you say, but only to the 150.
kglinz posted 10-16-2005 12:52 AM ET (US)     Profile for kglinz  Send Email to kglinz     
Having re-read my last post, I didn't express my point well. I think that if it's true, that the only difference between the 135 and the 150 is the VTEC, then there is no diffence in power until the engine is at 4500 RPM or above. Neither engine is using VTEC below 4500 RPM. On the 150 the VTEC causes the valve timing to change above 4500. This increases the HP/Torque on the 150. To add the VTEC system to the 135, changing it to a 150, will certainly increase top speed and higher RPM power, but will not cause any difference in power below 4500 RPM.
jimh posted 10-16-2005 11:48 AM ET (US)     Profile for jimh  Send Email to jimh     
This discussion has me thinking. Going on the assumption that the HONDA BF-135 and BF-150 are really identical, except for the firmware in the controller, then, yes, I agree with kglinz.

Kglinz points out that there will be no difference in performance between the BF-135 and BF-150 below 4,500-RPM, i.e., the point at which the valves change to the other cam profile. This seems entirely reasonable. And, as he also mentions, it may be possible that there are other tweaks in the firmware which pull more horsepower from the engine that will be missing in the BF-135. It is hard to verify this without insider knowledge.

I also acknowledge that in the past there were many instances of engines where were based on the same power head and tuned for different horsepower output, but, in the old days, at least there was some mechanical difference between them. It might have been as simple as a restrictor plate in the intake path, but at least there was some physical difference. With these new all-electronic engines, the difference is often just a few bits of code in the firmware. This makes it harder for me to accept the marketing and pricing differential.

Also, in the HONDA case, it seems somehow unfair that the BF-135 engine has to carry around the weight and complexity of the VTEC valve train which will never be used! This is like adding insult to injury!

Does HONDA do this in their vehicle engines? I doubt it. I cannot imagine they would go to the expense of building the more complex VTEC engine and then install it in a vehicle never to be used! Please comment on this if you have good information about HONDA automobile engines with and without VTEC.

zpeed7 posted 10-16-2005 08:04 PM ET (US)     Profile for zpeed7  Send Email to zpeed7     
I was more of a rotary fan, but I had a lot of friends with highly modified cars with Honda engines. As far as I can remeber you could interchange heads between engine blocks, let's say a Integra GS-R(Vtec) and a Integra RS(non-Vtec), but the heads were not the same. The non-Vtec heads were different from the Vtec ones. As an interesting note, when turbocharged the non-Vtec models made more ultimate HP than the Vtec ones. The Vtec heads suffered from blow-by at high pressures.

As far as the Vtec being controled by a ground wire, I'm pretty sure that's true, I remember lot's people rigging their own Vtec controllers with a simple button instead of paying 300$ for the ones sold in the aftermarket.

Peter you could check many of the performance Honda shops that modify stock Honda ECU's maybe they could find some extra ponies in there.


Perry posted 10-16-2005 09:01 PM ET (US)     Profile for Perry  Send Email to Perry     
I was told that the BF150's paperback-sized electronic control unit (ECU) orchestrates a sophisticated range of adjustments to optimize power throughout the powerband. Maybe the BF135's does too minus the operation of the VTEC.

I know that at 3250 rpm, the ECU commands the air intake shutter valves to open within Honda’s dual-stage induction (DSI) system. The electronic switch from long air-intake runners to a shorter, higher-volume design allows the motor to get the air it needs to continue building torque and horsepower as rpm spools up. I can hear and feel when this occurs on my BF135.

Jim, I too think it is unfair that the BF-135 engine has to carry around the weight and complexity of the VTEC valve train and it isn't used. The same thing is true for the BF200 vs. the BF225. The BF225 gets its extra ponies from VTEC while the BF200 does not but carries the weight of the system. It is interesting that Yamaha's F250 is the same motor as the F200/F225 but the F250 gets variable valve timing for its extra HP. The F250 weighs 20 lbs more so this, and the fact that the F250 was developed after the debut of the F200/F225, leads me to believe that the older models do not have the variable valve train installed. I wonder how the F225 develops 25 more HP than the F200? Same motor. Maybe it is just the firmware in the ECU that gives it more HP?

zspeed7, thanks for the tip, there are lots of performance Honda shops here in Hawaii. Maybe I'll check to see if they can modify the stock ECU's to allow the VTEC to operate.

zpeed7 posted 10-16-2005 10:07 PM ET (US)     Profile for zpeed7  Send Email to zpeed7     

You might also want to send an email to these guys:

Even though they specialize in Mercury engines they pretty much work in any outboard. They have even added nitrous kits to some Honda outboards.(See episode #25 of Mosnter Garage, the Shark Boat episode). Maybe they have a few tips.

LHG, I linked this one up just for you:


LHG posted 10-17-2005 01:03 PM ET (US)     Profile for LHG    
I would think that any Honda mechanic, who has been to training school on the 135/150's, could tell you exactly what the difference is and what is needed for the upgrade?

Or is this a deep, dark Honda secret, and the mechanics are sworn to it?

Does anybody know how to upgrade a Verado 200 to the 275HP version, or a 135 to a 175?

It is interesting to hear that a 2 stroke 150 Optimax, which is no dog in it's own right, can be outrun top end by a conventional 4-stroke. It seems the 4-strokes are really starting to show their potential, and that all this talk that they can never equal 2-stroke perfromance is going by the wayside. Are there any of the big three Japanese companies yet advertizing that their models will out-accelerate a Verado, as Perry seems to indicate? Any magazine or PBR articles yet on 4-stroke against 4-stroke perfromance?

Sonic posted 10-17-2005 01:33 PM ET (US)     Profile for Sonic  Send Email to Sonic     
Knowing Honda, as I used to work on alot of Civics and Integras, the ECU is the same as the automotive application of this engine (Accord, CRV, Element), but with a different software tune.

The master of Honda ECU tuning is I wouldn't be surprised if you could send it it, have them analyize it, and modify it for your needs. They add VTEC fuel/timing maps all the time.

Peter posted 10-17-2005 01:57 PM ET (US)     Profile for Peter  Send Email to Peter     
"Any magazine or PBR articles yet on 4-stroke against 4-stroke perfromance?" Yes, Suzuki v. Verado. Verado lost.
LHG posted 10-17-2005 06:01 PM ET (US)     Profile for LHG    
Peter - which was the fastest 0-30 acceleration? Has Suzuki found a way to overcome the supercharager's acceleration?
Peter posted 10-17-2005 06:41 PM ET (US)     Profile for Peter  Send Email to Peter     
Larry, I don't specifically recall any numbers having been given but I also do not recall any remarks or comments that would suggest that the Verado acceleration was noticibly better or worse.
Actually, if you look at the Verado's 0-30 acceleration relative to the Optimax, the Verado usually comes up short. See the 190 Outrage test report for example where the 150 Optimax turns in a 5.6 second 0-30 time versus the 150 Verado's 9.0 second 0-30 time.

I tend to believe that the Verado leaves an impression that it is quicker than it actually is because of how quiet it operates. The typically expected audible input from the motor which is linked to acceleration is not there.

With respect to the V-TEC's operation, I tend to agree with Kglinz. Based upon the information available from Honda, it doesn't seem that there should be any difference between the BF 135 and the BF 150 below 4500 RPM.

LHG posted 10-17-2005 08:19 PM ET (US)     Profile for LHG    
There seems to be a few inconsistencies in the Whaler performance data. For the 210 Outrage, they show the 175 Opti at 7.8 sec 0-30, while for the 175 Verado, 8.2 sec.
And the Verado is faster top end, while being much quieter running.

Those numbers are close enough for most buyers, combined with much quieter operation and DTS, to spend their money in favor the Verado. Why deal with possible 2-stroke DFI problems, which we are seeing plenty of here, this time around with various E-tecs, when you can get a super smooth, trouble free 4-stroke?

And I think I have figured out what Whaler is doing with respect to the supposed differences in fuel weight, since Peter here has accused them of tilting performance in favor of the Verado. Keeping in mind the Florida heat and humidty during 6 months of the year at Edgewater (the test sites), and that internal combustion engines loose 15% of their HP during these days, it appears they are using fuel weight, probably as designated by the Merc engineers, to overcome the HP loss when comparing engines tested when it is cool and dry in the winter months.

I seem to see a pattern where most of the Opti's were tested in the cool, dense air, while the Verado new release production schedule seems to have them being tested in the humid dog days of summer. Edgewater is one hot, humid place for 6 months!

So when you're comparing fuel weight on the Whaler boats, also look at date tested. It's very important, 15% worth!

The 175 Verado, incidentally, looks like a strong performer, a lot better than the 135 or 150's. It has a pretty good HP to weight ratio also, and seems to be the one to buy if boat rating allows it. It's also in a class by itself, since only Suzuki has a 175 4-stroke on the market.

Perry posted 10-18-2005 10:57 PM ET (US)     Profile for Perry  Send Email to Perry     
Larry, yes the Verado 175 seems to have a much better power to weight ratio than its sister, the Verado 135. Is your Outrage 21 going to be blessed with one in the near future?

Speaking of the Suzuki DF175, I noticed that it is the exact same weight as the DF150. The DF175 gets its extra HP from variable valve timing while the DF 150 does not. I wonder if the only thing Suzuki is using to get the VVT to operate is different ECU firmware?

Peter posted 10-19-2005 07:44 AM ET (US)     Profile for Peter  Send Email to Peter     
Larry, the "inconsistency" (I would call it a "consistency") you noticed might be related to the fact that the 175 Optimax powered 210 Outrage was loaded with a full tank of fuel (95 gallons) plus 20 gallons of water while the 175 Verado powered Outrage was run with a whopping 12 gallons of fuel in the fuel tank and no water in the water tank! Total weight of the 175 Optimax powered Outrage was 4,251 lbs. Total weight of the 175 Verado powered Outrage was 3,624 lbs. Despite having 600 lbs. less to push around, the Verado 175 still came up short on the 0-30 MPH time.

Perry, I suspect that we will see it to be quite a normal practice by manufacturers to dissable mechanisms such as VVT for the lower HP models built on a common platform. It's much cheaper and easier for the manufacture to make all of their motors in a given family with no structural variations on a single assembly line. Then all they need to do to get different HP outputs is simply program the EMM to enable the technology. It would seem that there could be a "tuners" market to enable a disabled feature in an outboard but it is currently illegal to make alterations to a motor to change its emissions output. Because there are no emissions checks like they have on a car to make sure the emissions compliance equipment is still functioning properly, I do wonder how any law enforcement official interested in emissions (if there are any) would ever know an outboard motor had been modified. Do they give it a sniff test?

jimh posted 10-19-2005 08:36 AM ET (US)     Profile for jimh  Send Email to jimh     
A decade ago (or longer) in the state of Michigan we used to have mandatory emission testing of passenger vehicles, but only in certain counties (based on the density of automobiles). You could not get license plates without having proof of passing a certified emission test. It was a boondoggle for auto repair shops. You had to pay $25 or more for the test, which took about five minutes to perform. If your car did not pass, you had to spend a certain amount of money in attempting to repair the engine so it would pass. I think it was capped at $250. Once a vehicle reached a certain age it was exempt from testing.

After years of testing emissions, and when the fleet of cars on the road in Michigan became modern enough so that 99-percent of them passed the test, someone finally woke up that forcing several million people to spend $25 every three years for the emission testing was an expensive way to monitor a pollution problem that no longer existed.

I don't think this same emission testing nonsense can be foisted upon recreational boaters in the current economic climate.

The HONDA outboard engine is a derivative of their automobile engine, and the reputation of the HONDA car motor is very, very good. I think this carries over to the marine application. However, I have to wonder if there is a problem with the engine orientation changing 90-degrees. With the force of gravity acting on all components in a completely different direction, I just wonder how all those bearings, oil passages, air passages, and water passages can work just as well as in the automotive application.

johnstanleyho posted 07-30-2014 03:29 AM ET (US)     Profile for johnstanleyho  Send Email to johnstanleyho     
[Nine years later, this discussion is revived--jimh]

The 150 hp Honda has some hardware changes as well. The VTEC Oil Spool is a functional one and not a dummy. When energized it allows oil into the valve galley to actuate the VTEC intake valves. The intake cam is also a different one with multi lobes to jack the larger cams moved into place by the oil pressure. The oil galley pipe for the VTEC camshaft is also different. The computer is different to accommodate the signaling for the VTEC.

If you were to upgrade a 135 to a 150 you would have to acquire these three critical pieces at a cost of roughly spool $159, Computer $300-400 (eBay), camshaft and additional lobes, fittings, ballbearings, springs and spacers $300 (eBay) oil galley pipe $100 (probable better off just buying a used 150 head and using it or cannablizing it) for a total more than $1,000--and that is with considerable bargain hunting and do it yourself head work.

It can be done but yeah, low end torque and midrange torque pretty much stays the same.< Worth it on a bass boat, not worth it on a cruiser working boat.

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