Evinrude 235 V6

[Dhadley]

Re: Evinrude 235 V6

When you look at a crossflow intake you'll see that each runner goes to one cylinder. Basically we cut away the divider between the 2 runners (on the carb side of the intake) so one cylinder will pull from both venturis of the carb. You can then use carbs with smaller venturis for more acceleration but still feed each cylinder more fuel. There are some carb mods but that's the basic deal. Some guys even connected the top, middle and bottom runners to create one big plenum. We never found that made enough difference vs. the work. Letting each cylinder pull from 2 barrels rather than 1 make a big difference.

 

[Faztbullet]

Re: Evinrude 235 V6

All the mod's listed are for a light boat, do the mod's and stick motor on a heavy turd and it wont get out of it own way....

 

[hitechredneck]

Re: Evinrude 235 V6

When you look at a crossflow intake you'll see that each runner goes to one cylinder. Basically we cut away the divider between the 2 runners (on the carb side of the intake) so one cylinder will pull from both venturis of the carb. You can then use carbs with smaller venturis for more acceleration but still feed each cylinder more fuel. There are some carb mods but that's the basic deal. Some guys even connected the top, middle and bottom runners to create one big plenum. We never found that made enough difference vs. the work. Letting each cylinder pull from 2 barrels rather than 1 make a big difference.

Thanks for the intake info.
That makes perfect sense, we do that with split plenum intakes to obtain more top-end HP on cars & on some multi-cyl bikes.
Most of the time it robs from the low-end. It's always a give & take scenario either way.

I might make a similar mod & cut a small angled notch in the runners instead of cutting them completely out, sort of like a performer RPM intake for car motors, theoretically it gives you a little of both sides, a happy medium.
Single runners give more torque & open runners more HP, same with long & short intake runners, if I'm remembering correctly.
Also, my opinion has always been, torque is what gets you there & HP holds you there.

Again, thanks for all the info. Every little bit helps.

How do you feel about polishing the crankcase surfaces and intake ports to a mirrored finish. On certain motors I polish the intake & exhaust, on 2-strokes I polish the crankcases too.
Most techs say to leave the surfaces a little rough to help with fuel itemization. My thoughts are similar if the motor doesn't reach normal operating temps, like in drag racing.
This motor will reach a normal operating temp, itemization shouldn't be a factor because of the thermal cycles.

I did this with our heads on our 606cid motors when we raced in bracket racing when we didn't follow the top-alcohol circuit. I polished everything and staged at 200-210 degrees versus most guys leaving @ 120-140.
Our dragster was the most consistent on the circuit too, but with the old style porting we ran very different ET's, not consistent at all.
That might had just been a coincidence though, we went thru a lot of changes during that time, that made it hard to pin point what helped the most. You know what I mean I'm sure.

My theory is, the smooth surfaces should let the fuel/air move a little more freely, increasing HP & torque.
I know on dirt bikes & PWC's this makes for a radical power curve, but these have expansion chamber exhaust systems to aid in that too.

How do you feel about polishing everything on the big marine 2-strokes?

 

[hitechredneck]

Re: Evinrude 235 V6

All the mod's listed are for a light boat, do the mod's and stick motor on a heavy turd and it wont get out of it own way....

Yeah, that's usually a rule of thumb, but sometimes weight placement is more important than overall weight. In some cases!
I can prove that with the weight I had to add to the front of our dragster to keep the front end down at launch. Adding 100lbs to the front half of the chassis and picked up 3 tenths, but that?s tires & asphalt, not boats & water.

I'm not racing, obviously with this style boat. I just want to extract as much free power as I can since I'm building another motor anyway. It's just a little labor.
I'm already getting triple takes when I max out @ 69-72 with this rig like it is. That's on GPS.
Other boaters follow & ask the same 'ol questions.
(You know what I'm talking about!)
"How did that old boat out run mine? I've got a bigger motor, yours is just an 175, how?"

I just tell 'em I have a chromed canuter valve or something like that. Most people don't know the diff. LMAO

All I know there is more potential in this motor because I passed on a lot of the mods I had intended to do at that time just to get it together so I could use it.
My father was on his way out & I wanted to get him on the water fishing before that happened, I'm glad I did too.

Now, since I need to split the crankcase to reseal it for a small air leak, I'm gonna do the modifications I intended to do to begin with.

I'm just gathering data, specs, & opinions for now. You know how it is, everyone wants more power from what they currently have. No difference here.

When I get done, come on down & I'll take ya out on some of our nice lakes here in TX, that is if they still have water in 'em at that time. I might just need to add big tires. LOL

You got any suggestions for a heavy bass boat? Reasonable suggestions! LOL

Oh, the pictures were a great help, then I found Al's specs he'd suggested back this last spring. Both matched up nicely.

I'll do a mixture of suggestions, add my knowledge from my technical back ground, and apply a lot of common sense, if I can find any coming out of my head. LOL

Hopefully it it'll all work out for the best. I guess we'll see.

 

[Dhadley]

Re: Evinrude 235 V6

Actually we've had good luck with the intake mod on even heavy boats. We do match the carb venturi size to the hull design and intended use. We have polished the intake and front half but did not see enough gain on the dyno or on the water to justify the effort. Crossflow motors set up below the mid 6000 range didn't see any gain.

 

[hitechredneck]

Re: Evinrude 235 V6

Actually we've had good luck with the intake mod on even heavy boats. We do match the carb venturi size to the hull design and intended use. We have polished the intake and front half but did not see enough gain on the dyno or on the water to justify the effort. Crossflow motors set up below the mid 6000 range didn't see any gain.

Thanks again for all the info, it's been very helpful.

When I get the other motor together again I'll let ya'll know how it turns out. I'll list my modifications & specs at that time.

What are your thoughts about chrome plating the megaphone and exhaust filler blocks to aid in flow & reduce carbon/oil build up?
I'm thinkin' about chroming every metal part related to exhaust flow.
What do ya think?

Hey, that brings me to another issue.
When I lower the motor down into the water, at least to the trim level, the motor loads up like it's being choked on the exhaust side, it'll barely idle, when I raise it up it idles normally. This is in gear or out.

I was thinking of modifying the exhaust megaphone or something to help it breath better, something similar to dry staking a Mercury "I think", whatever that is.
I thought about enlarging the 2 half inch holes @ the top of the midsection to help relieve exhaust pressure too.
Any tips on this?
Can this be done on an OMC?

This is a 25 inch shaft model, if that helps.

Again, thanks for your input.

HTRN

 

[Scantic 525]

Re: Evinrude 235 V6

Perusmodin on siivota kaikki portit. Seuraava modi on asentaa joukko korkean suorituskyvyn reeds ja täyteaineiden lohkot, puhdistaa siirtoportin alue, leikata kampasimpukka siirtoportissa, ja asentaa joukko 235 hiilihydraatteja (1 3/8 bores) Katso liitteenä kuvia ja postitse vastata muihin kysymyksiin

235v6

 

[Scantic 525]

235v6: n

 

[Scantic 525]

235 is in a league of its own

 

[Scantic 525]

Re: Evinrude 235 V6

Millaiseen veneeseen laitat tämän?