intake manifold choice

[hudman]

i have a 1985 mainship 36 aft cabin with twin 270 hp crusaders, which are 350 gm. i am replacing the tired engines with new long blocks from michiganmotorz. the new engines are identical to the originals. My question is,,,, Will I see any improvement with edelbrock torquer intake manifolds?
these are alumimum,, this boat has a full closed cooling system, so corrosion is not an issue. I have new holley 4150 spread bore carbs,marine versions, 650 cfm, and new delco hei est distributors. the rpm range that I will be in most of the time is 1500-3400 with WOT at around 4400-4600
thanks and happy holidays

 

[Fishermark]

Re: intake manifold choice

A few notes:

The Edlebrock Troker manifold is a single plane manifold - really only good for high rpms. You would be better off with a dual plane - like the Edlebrock Performer.

Also, while I am not a Holly expert, I believe the Holley carb you mention is a square bore - not a spread bore. It's also important to make sure these are marine carbs - not automotive. Same thing with the distributors - be sure they are suited for marine use.

Bottom line - I would suggest staying with the Edlebrock line of products - the Performer manifold and the Edlebrock 1409 Marine carb.

 

[hudman]

Re: intake manifold choice

No these carbs are spread bore marine holleys, the ones recommended by crusader for a direct replacement for the old quadrajets. the distributors are delco marine est units. I just ordered 2 performer intakes,,, do you think there will be a noticable improvement over stock?
thanks

 

[SuperNova]

Re: intake manifold choice

No these carbs are spread bore marine holleys, the ones recommended by crusader for a direct replacement for the old quadrajets. the distributors are delco marine est units. I just ordered 2 performer intakes,,, do you think there will be a noticable improvement over stock?
thanks

Probably not much, the Performer intake is pretty much a stock replacement intake with slight improvements. You might have been better off with either a performer rpm or eps. I also would have used the Edelbrock marine carb due to the design that keeps the gaskets above the fuel level.....less chance of leaks that way. Just my op.

 

[Fishermark]

Re: intake manifold choice

the rpm range that I will be in most of the time is 1500-3400 with WOT at around 4400-4600

That's your key right there. There is only so much you can do when it comes to intake designs at the lower rpm range. You can go with the Performer RPM as mentioned, or even the RPM air gap. What's on the original engines? The biggest improvement would have been to go with Vortech heads - but you say they are supplying engines like the original? Is it too late to upgrade the heads?

 

[hudman]

Re: intake manifold choice

yes, its too late on the engines, i didnt want to spend the big extra to go with the vortec motors,, it really gets expensive in the ccr motor, and none of my old stuff would have bolted up. however its not too late on the intakes, just ordered them an hour ago, they wont ship until tomorrow. ill look into the performer rpm

 

[Bondo]

Re: intake manifold choice

yes, its too late on the engines, i didnt want to spend the big extra to go with the vortec motors,, it really gets expensive in the ccr motor, and none of my old stuff would have bolted up. however its not too late on the intakes,

Ayuh,....

The Vortec Head up-grade Doesn't require that the Whole motor be of that vintage,...

Vortec Heads can be bolted onto the motors you've Got,....
Just by changing the Intake Manifold to match the Vortec head intake bolt pattern....
And,...
Vortec Heads are pretty darn Cheap, boat wise anyways....
Even Brand New from GM, their pretty Cheap....

If your old motors were already equiped with 4bbl. Carbs,....
You're in for a Major Disappointment...
You're plan will bring you about the Same hp you had before....

Going to Vortec Heads,+ the Carb/ Intake Mark mentioned will net you about 30+hp, per motor....

 

[180shabah]

Re: intake manifold choice

That is a pretty hefty boat, it just isn't worth trying to squeeze a few more ponies out of each engine. It just won't make much difference. If you really wanted a "noticable" increase then we need to talk about 383 vortec but that will be some major money. And again with the size of that boat, just how fast do you need it to go?

 

[hudman]

Re: intake manifold choice

After some studying, it seems that the edelbrock performer RPM intake makes the most torque at 3500 rpm, it sounds like the best overall for my application.
the performer air just helps with more cooling , which is not an issue on a boat. Yes this is a heavy boat, and mega horsepower is not the answer, just want it to be as efficient as possible. the old motors were so dead, that i could only get about 2200-2400 rpm out of them. thanks for the help, and happy holidays

 

[Fishermark]

Re: intake manifold choice

One last note - if you do go with the RPM, just know it is a square bore manifold - not a spread bore like the Performer. If your carbs are spreadbore you may need an adapter.

 

[mylesm260]

Re: intake manifold choice

Unfortunatly, it's very difficult to tune a carbed manifold for bottom end torque.

Because you are trying to combine the fuel and the air before the runner, if you use a long runner, the fuel will no longer be atomized, and won't burn properly.


EFI manifolds can have runners as long as they want, because the fuel is added and atomized right before the intake valve. If you want bottom end torque and fuel economy, than you need manifolds with really long runner, which basically means EFI.

 

[Gazza1]

Re: intake manifold choice

What ever you do DON'T use a single plane manifold.. These have Rpm but NO power till the engine reaches above 3000.. I am with all the others that say to stick to the original execpt the intake, the alloys ane indeed lighter.
The other thing you could use is alloy manifolds, have then powder coated inside as well as outside, FWC cool them.

 

[Gazza1]

Re: intake manifold choice

I forgot to add.. Make sure that the new engines haven't been bored out too much, 10 or 20 thou if you are using FWC, 30 thou and up run a lot hotter and you will have poblems keeping them cool. Yhis is what we have found downunder.. Maybe not a problem up there I don't know.

 

[hudman]

Re: intake manifold choice

these are not rebuilds, they are fresh NEW zero hours motors, from michiganmotorz. thanks to your imput, ive made my choice, ill let u know the results in a month or so

 

[dan t.]

Re: intake manifold choice

if you can find them the edelbrock sp2p is designed to increase bottom end torque, idle to 4500 rpm these are spread or square bore and they work very well. I have used them on a couple of 4x4s and installed one on a 26 ft zeta with a chev 350, happy customer.merry christmas to all and hope for an early spring

 

[jerryjerry05]

Re: intake manifold choice

Since your spending,Send your props out to a good wheel shop and have them redone.Everyday use can warp them.Have them redone and you will notice a difference.Jerry