1979 E'rude 150 hp increase? DHadley help please

[H1990]

I've got a '79 150 crossflow. Was going to upgrade, but the motor was rebuilt about 5 years ago, and got a new lower unit as well. I have a friend who swears that the bore and stroke are the same on a 150 and 200 crossflow. He said that the only difference between the motors is the carburetors... Is this true? Would switching carbs and putting 200 hp carbs on this motor give it 200hp? I can get the carbs cheap, but don't want to believe wives' tales if that's what this is.

 

[jimmbo]

Re: 1979 E'rude 150 hp increase? DHadley help please

No, you can not make a 150 into a 200 by just changing carbs. Change other things like the block, exhaust tuner, perhaps reeds and cylinder heads then you would be getting close.
Think of car engines, there were lots of chev 350 made with hp ratings from 140 to over 370hp. It took more than just a carb change to made more power from the same bore and stroke.

 

[clint]

1979 E'rude 150 hp increase? DHadley help please

Hmm? I would do more research. I agree with Jimmbo about reeds and different cylinder heads, timing etc. It would take more than carbs. I feel even if you have a great running 150 leave it alone and avoid a bigger problem.
Clint :$

 

[emdsapmgr]

Re: 1979 E'rude 150 hp increase? DHadley help please

The 200 block is different from the 150/175 versions. It is a high port block-like the 235, but without the bubble back exhaust. The 200 has the larger 1-5/16" throat carbs with the pull over jets like the 235 and the intake filler blocks. Heads are all the same on 150/175/200. Ditto for the tuning megaphone. If you put the 79 200 carbs on a 150, it will overfuel-you will have to jet it down slightly, think I went down to 57's. You can absolutely improve your hp with the engine. Add the larger carbs and intake fillers blocks. A set of composite reeds is a nice addition. If you want more add a set of early 235 heads you will need to jet back up again. If you leave the timing at 28, you will need to burn premium. Be careful when jetting, as not all 1-5/16" carbs are created equal-they come with many different jetting configurations.

 

[Dhadley]

Re: 1979 E'rude 150 hp increase? DHadley help please

The 150 and 175's are identical as far as the powerheads. The 200's use the same block casting but have bigger ports cut on the same centerline, therefore higher port timing especially on the intake.

All the V6 flatback crossflow motors have the same bore & stroke, intake system, ignition system, tuner and gear ratio within a given year. There are some differences in heads and carbs.

On stock motors we've found that the 150 XP/GT heads work the best and you can stick with 87 octane.

Some 150 XP/GT blocks had 200 port timing or real close to it.

You can swap carbs around and make gains in certian areas but only at the expense of something else. Large throat carbs may give you slightly more rpm on top but only if you're turning it up anyway. Smaller throat carbs will provide more acceleration but may not breathe as well at higher rpm.

You'd have to have a pretty good hull to see the small differences in torque between a 150/175 and a 200. If you were rebuilding a 150 or a 175 then I'd suggest opening up the ports while you're in there. Real simple on a mill.

I'd concentrate on getting the most out of what you have. We've done this many times for customers (make 200 blocks out of 150's) and I don't remember one that was happy. In the end we went back and maxed out the set up, that's where the gains are.

 

[H1990]

Re: 1979 E'rude 150 hp increase? DHadley help please

Thanks fellows. What's the simplest and cheapest thing to do in order to max out the set up that I have?

 

[Dhadley]

Re: 1979 E'rude 150 hp increase? DHadley help please

Let's look at what you have. What kind of boat? What design hull? Jackplate? Where are you at now -- what rpm w/ average load? What top speed? What pitch prop?

From there we can figure the percentage of slip and see where you're at. Once we know where you're at. we can figure how to get to where you want to be.

 

[H1990]

Re: 1979 E'rude 150 hp increase? DHadley help please

Ok. Right now the transom, floor and stringers are being reworked with Coosa Board Composite, so rpm @ WOT I'm not sure on due to the fact that the boat will be about 200-250 lbs lighter when I get it back (and that I didn't have it long when I put it in the shop). It's a 1985 Bumblebee 178 ...typical mid-80's Bumblebee design. The Jackplate is a 6" Hijacker. Before I put it in the shop, (according to the old man I bought it from) the top end was about 62-63 mph w/ 1 person in it/ 55-57mph with 2 people tournament ready. It has a 24 pitch prop on it. The motor was rebuilt in 2001, bored 30 over, new bearings, rods, rings, etc along with new lower unit. I just got it from the old man that had it about a month ago and put it in to have the work done on it. I can email you a picture of it if that would help. BTW, I really appreciate any advice you can give me.

 

[Dhadley]

Re: 1979 E'rude 150 hp increase? DHadley help please

Cool boat. Let's hope Ron Green gets on board on this thread -- he has a Bee also. A bit newer 150 but I'd say you're in a good position once it gets back together.

I would suggest we get it running and test exactly where the motor was located before and with the same prop. That will establish our baseline. Obviously being lighter should help some. Be sure to check out the water pressure.

Is the gearcase a standard stock unit? Or does it have a nosecone / low water pick up? I assume it's not the Lightning gearcase, right?

 

[H1990]

Re: 1979 E'rude 150 hp increase? DHadley help please

Yes. The gearcase is a standard stock unit. I should get it out of the shop this next week. It does not have a nosecone or low water pickup. I'll post again on the thread once I run it and get the numbers. Thank you a ton.

 

[Dhadley]

Re: 1979 E'rude 150 hp increase? DHadley help please

You're welcome. See if you can IM Ron and get his input on this. I know he's on the prop forum a lot.

 

[H1990]

Re: 1979 E'rude 150 hp increase? DHadley help please

DHadley:
Ok, here's the deal on this boat. I have a 24p three blade turbo on it, at WOT it's turning about 5600 rpm's and the speedometer is reading 63mph with 1 person in it. I don't have a GPS. The fellow I bought the boat from said that the OMC mechanic that built it did something to it to turn the rpm's down so that it wasn't bumping 6000 (I have no idea what). It has a 6 inch Hijacker on it. I have been considering switching props and going to a 24p Raker, a 26p Raker, a 25p Powertech, or a 25p 4 blade Ballistic. I also have a stingray hydrofoil, but haven't ever put it on it. I have been advised that I could drop the Jackplate back another 6 inches and it would pick up 2-3mph, but don't know if that's truth or fancy imagination on his part. Any thoughts?

 

[Dhadley]

Re: 1979 E'rude 150 hp increase? DHadley help please

Offhand I don't recall what setback Ron is running. I'm pretty sure he went to a Turbo Lightning on his boat. A 25 I think.

Anyway, assuming the speed-o is correct (it's probably off a little) you're at about 9% slip. Lets use that as a baseline. If you get the chance to verify the speed by GPS then we can adjust the baseline if we have to. 9% is pretty darn good.

First we need to look at the motor to see what, if anything, they've done to "slow it down". We'll need to start by verifying the timing. Then do a sync-n-link to make sure we're getting all we can. Maybe all they did was lower the jackplate to create more drag.

Then we need to look at ride attitude. If you need a lot of positive trim input to carry the bow then more setback will probably help. But so will a prop with more bow lift.

 

[H1990]

Re: 1979 E'rude 150 hp increase? DHadley help please

I called the mechanic that built the motor, and he said that he didn't mess with the timing. The only thing he said they did was prop it. Also, what's a good base point to start with in adjusting height of the jackplate? If I put a yard stick on the bottom of the pad out to the cavitation plate, how high above the straight edge should the cavitation plate be set to start with?

 

[Dhadley]

Re: 1979 E'rude 150 hp increase? DHadley help please

The motor height or X deminsion will depend a lot on what style prop you're going to use. Stick with the 24 Turbo and put that plate up about 4". We can adjust from there.

 

[H1990]

Re: 1979 E'rude 150 hp increase? DHadley help please

Actually I already swapped the 24" Turbo for a 24" Raker. The Turbo was worn out and needing to be rebuilt. Would the raker need about the same amount of height as the turbo?

 

[Dhadley]

Re: 1979 E'rude 150 hp increase? DHadley help please

About the same. Maybe a bit less. But that's comparing new or good to new or good. A new / good 24 Raker will probably run higher than a worn out Turbo.