What makes an engine a "Vortec" and what dif does it make?

[tmh]

Re: What makes an engine a "Vortec" and what dif does it make?

Also wanted to add it's quite popular to bolt on vortec heads to a non vortec "era" block but your not getting the full power that a vortec motor puts out. The vortec's have a more aggressive cam and it's a roller with roller lifters.

This could very well be what I have, as I think it's a 1992 or older V8 350 engine so the "Vortec" 8-bolt configuration part could well have been a mod, no idea what else was done, maybe my mechanic can go over it with me. Interesting info........

 

[John_S]

Re: What makes an engine a "Vortec" and what dif does it make?

Hp is at prop and used Merc factory numbers. They produced a 350 vortec TBI which flows same as a carbed 4brl intake. It is rated at 280hp at prop. The 2brl is 250hp at prop. The MPI, which flows more than carb is 300hp at prop.

Marine SBC flat hyd cam and roller cam, produce the same hp. Former has longer duration and less lift than roller. The roller cam was used before vortec heads were available. It is not vortec specific.

Vortec came from vortex, which was trying to describe how the fast-burn heads work.

 

[Rock Hall]

Re: What makes an engine a "Vortec" and what dif does it make?

Aprevious poster said that not all Vortec engines had the Vortec heads.
I'm still wondering if my 94 has a real Vortec or not. My 95 Safari just had a plain 4.3, not called a vortec.

 

[John_S]

Re: What makes an engine a "Vortec" and what dif does it make?

The original poster was refering to 350 SBC, and then some V6 replys got mixed in. It might be worth starting a seperate thread so some of the V6 crowd can weigh in. If you search, you should find a good 4.3V6 referance by Mikdee. It had what changed when specifics.

 

[Bondo]

Re: What makes an engine a "Vortec" and what dif does it make?

I'm still wondering if my 94 has a real Vortec or not.

Nope,..... The Fast-Burn Heads(Now known as Vortec Heads) were Not Intro'ed til 1996.........

 

[tmh]

Re: What makes an engine a "Vortec" and what dif does it make?

OK, as the original poster here, I want to continue the discussion of the 350 V-8 Vortec issue. I have searched around the internet some and now have another question about my engine. Assuming the the engine is 1987-1992 it lookslike that is pre-vortec....so, if it currently has the 8-Bolt intake pattern (which it does) it stands to reason that it was an engine mod. Now, i have read here and elsewhere that the power increase in the Vortec comes from the Vortec heads.

So, my question is this. IF someone did mod the engine can I assume that if the intake was changed to the Vortec style then the heads were changed also? is it an both or neither mod or can someone just change the intake (and would it ever make sense to do so)?

Also, what do I look for to know if i have vortec heads (or does the bolt pattern on the intake ensure the heads are vortec also)?

Thanks for the education guys. Interesting stuff.

 

[RCSConstruction]

Re: What makes an engine a "Vortec" and what dif does it make?

You would have to drill and tap the heads. I HIGHLY doubt someone did that. I know some drilled the old manifolds to fit on a vortec head but not the other way around. Centerbolt valve covers are a good sign as well as the end cast. Some Vortec's have a "triple triangle" pattern in the casting. Like the double humps in the days of old.
Pop a valve cover and give us some numbers. We can tell you everything about that head.
Don't forget it's not just the head, it's the cam profile and roller valve train that add's to the HP numbers. Like bondo said up above. Bolting vortec heads to a non-vortec era block nets about 30hp extra although I have heard up to 50.

 

[Bondo]

Re: What makes an engine a "Vortec" and what dif does it make?

is it an both or neither mod

Ayuh,............ Exactly.........

Even though I actually saw it happen on some Dumb***** TV show,.......
It Can't be Done.......

The Intake Ports on the Vortec heads are a full .200" Higher than any previous Chevy head....
Talk about mismatched Ports,..... Nearly 1/4" is Alot of open space.....

Back on that Ridiculous TV show, they tigged up a great big Hump on this fancy mismatched shiney intake manifold,....After they had used their massive Machineshop to drill,+ tap everything,...
And it Did run.....
But the Whole motor was a mismatch of parts that I'm sure Didn't, cause it Couldn't, Live very Long.......

Kinda 1 of those All of the Best Parts,.... For the Wrong Application things......

 

[John_S]

Re: What makes an engine a "Vortec" and what dif does it make?

Merc never made a 4brl carbed Vortec 350. Given you have a 4brl carb, it is either a modified marine SBC or any possibility of replacement engines, remans, backyard rebuild, etc. Since the seller didn't even know he had vortec heads, most likely another owner did the work. You mentioned it was in a go-fast boat. It could easily have modifications to the vortec heads (porting, valves), and a performance cam. Finding out exactly what you have will require a teardown. You can get additional info from head and block casting numbers, but won't help you with cam, pistons, and crank.

 

[TilliamWe]

Re: What makes an engine a "Vortec" and what dif does it make?

JUst for reference my 97 Vortec 5.7 has a TBI system on it. And I "think" that if you took my throttle body off of it, a 4bbl carb would fit right in its place. So that "may be" how a 4bbl carb could be on an 8 bolt intake manifold on Vortec heads?

 

[tmh]

Re: What makes an engine a "Vortec" and what dif does it make?

Merc never made a 4brl carbed Vortec 350. Given you have a 4brl carb, it is either a modified marine SBC or any possibility of replacement engines, remans, backyard rebuild, etc. Since the seller didn't even know he had vortec heads, most likely another owner did the work. You mentioned it was in a go-fast boat. It could easily have modifications to the vortec heads (porting, valves), and a performance cam. Finding out exactly what you have will require a teardown. You can get additional info from head and block casting numbers, but won't help you with cam, pistons, and crank.

Great info, thanks. I won't be tearing it down to find anything out that isn't easily seen! I'll try to get a casting # from the head just to satisfy my curiosity. It is what it is though and it should perform very well on my 19' (though weighs like most 20-21') boat. I'll report back the upgraded performance vs. my 305 when I ge *** on and in the water - hopefully soon!

I agree that it is likely a mod by a previous owner to get more mph.

 

[John_S]

Re: What makes an engine a "Vortec" and what dif does it make?

tmh,

Was this the ebay engine you purchased? Memory is slowly coming back. ie from someone in Cold Brook NY? The auction said 350 Mag, right?

The head casting numbers will help. Most likely they are standard GM 350 vortec heads. You would be able to make sure they were not 305 vortec heads, or a slight possibility of an aftermarket head.

If you wanted to find out if it has the factory GM roller cam, you could measure a push-rod. It is probably not a bad idea when you have the valve covers off to staticly adjust all the lifters, anyway. It still won't tell you if they changed the roller cam. Just that it has one. I would have to find what the length is, but it is shorter than the flat hyd lifter pushrod.

 

[John_S]

Re: What makes an engine a "Vortec" and what dif does it make?

TilliamWe,

Possible, but not likely. Replacing it with a carb provides no hp increase, only more maintenance. That is usually only done in conjunction with more radical modifications such that the stock MAP is a problem, ie radical cam, very high flow heads and intake, etc. I think other ignition and fuel pump parts would need to be changed for converting to carb from efi, too. Checking the casting and part number on the intake would validate that. My guess is that it is an aluminum aftermarket intake.

 

[RCSConstruction]

Re: What makes an engine a "Vortec" and what dif does it make?

TilliamWe,

Possible, but not likely. Replacing it with a carb provides no hp increase, only more maintenance. That is usually only done in conjunction with more radical modifications such that the stock MAP is a problem, ie radical cam, very high flow heads and intake, etc. I think other ignition and fuel pump parts would need to be changed for converting to carb from efi, too. Checking the casting and part number on the intake would validate that. My guess is that it is an aluminum aftermarket intake.

Is it only Volvo Penta that made a 4bbl vortec manifold?
I know that hot-rodders look high and low for marine vortec manifolds.
Is it possible, like my volvo penta, that the merc had a 2bbl on a 4bbl manifold?
I really don't see why chevy/merc/volvo would all make a different intake?

 

[TilliamWe]

Re: What makes an engine a "Vortec" and what dif does it make?

I am thinking the same thing as you RCS. And as far as I can tell, my intake manifold is aluminum, cause it is not very heavy at all.

 

[RCSConstruction]

Re: What makes an engine a "Vortec" and what dif does it make?

I am thinking the same thing as you RCS. And as far as I can tell, my intake manifold is aluminum, cause it is not very heavy at all.

In the front of the intake on top next to the carb and runners you should see some casting numbers on it, might be hard to see if painted heavily.
Also, if you pull the Tstat and look inside the water port it should be brass lined, not sure if it's brass but it's a gold'ish soft metal.
If it's not and you are in salt water without a closed cooling system you could have trouble down the road. Just an FYI

 

[tmh]

Re: What makes an engine a "Vortec" and what dif does it make?

tmh,

Was this the ebay engine you purchased? Memory is slowly coming back. ie from someone in Cold Brook NY? The auction said 350 Mag, right?

That's right - I've had a few threads on this from various angles....should I/shouldn't I?, etc. Well, I bought it and now am just waiting to get it put in! I am anxious to see how it performs vs. my 305 2bbl.

Like all things here on iBoats forum, I went into this not knowing one darn thing about these engines, now I am at least able to understand what you guys are telling me! It's fun to learn this stuff as I spend money on my boat!

 

[TilliamWe]

Re: What makes an engine a "Vortec" and what dif does it make?

Well it should outperform you 305/2bbl handily!

 

[John_S]

Re: What makes an engine a "Vortec" and what dif does it make?

FWIW: When I was looking for a vortec intake, did not find any marine gm available. They have a couple of $200+ alum intakes that look very similiar to Edelbrock intakes. The ones with brass or anodized water jackets were available at marine engine specialty shops, but were house brand or brand-less.

Don't know what Merc used for TBI EFI engines, but they went to all MPI anyway. Didn't find any on ebay when I was looking.

I know little about volvos, outside of some of their 2brls used a 4brl intake with a plate. That was very thoughtful for an easy upgrade. This is another one that I didn't find on ebay (used).

I found a new cast-iron 4-brl Q-jet vortec intake, but there were many a problem reported about them. Stay clear.

I ended up choosing an Edelbrock alum for my fresh-water boating. Used zinc chromate primer and Merc black to make it look stock.

 

[thedillybar]

Re: What makes an engine a "Vortec" and what dif does it make?

Hello - wondering if you could comment more on this swap.


Currently considering going from a 1987 block (which was remanufactured 2 yrs ago, before I bought the boat) and putting on vortec heads and a vortec intake to hopefully add 30-40 hp. Have heard nothing but rave reviews on the vortec heads......how have they worked out for you?