Is bigger really better???

[Camfreek]

I was talking to a guy at a local machine shop today and he had said an easy way to get more power from my hot air car is to find a 4.1 motor. I was told by him that all the internals are the same it just has a bigger bore. Is taht true? He siad everything will bolt right up to it and no one will ever tell the difference!! Just wonder if anyone has done this with a hot air and if it is even worth the time or money?

 

[Grumpy]

4.1 stuff has been beat to death also.. cracks in the block I guess are common. some swear by it others don't.. It's not goin to be "cheap" either

 

[charlief1]

Look for a post in the engine section under 4.1. You can also stroke it to 274 cubes with a stroker kit. "There's no repacement for displacment"

 

[spx-7]

Bigger is better

Look for a post in the engine section under 4.1. You can also stroke it to 274 cubes with a stroker kit. "There's no repacement for displacment"

You can actually go to 290 cubes with 3.750 crank.

 

[Boost231]

4.1's are sick. just not sure about the cracking issue. that would suck to spend alot of money on a block and have it get a hair line crack.

 

[decarlo sloan]

4.1 is the same as a hot air block just more displacement. Whats your goals it might be a waste of time and money if you just want to run 12's

 

[Jerryl]

.......... Whats your goals it might be a waste of time and money if you just want to run 12's

Good point, but too many others factors involved in the goal.
It will not be a waste if he wants to run 12's, Non-IC'd on pump gas at 15 psi, with a 3700 See what I mean?
So I agree. Need some real specifics on the goal. :smile:

 

[turbofish38]

Wouldn't the big draw back be the lack of a bolt on turbo for the extra cubes? It would be counter productive to dump a ton of cash into the block only to have to dump some more with a custom intake manifold and turbo. I'm in the process of building a 4.1 with a TA33. And I'm thinking about how much power is being lost to the small turbo and intake manifold.

 

[novaderrik]

the beauty of going with a motor with more cubic inches- even if you aren't looking to run 9's or something- is that it will be more drivable in day to day usage due to the extra torque. and a bigger bore almost always makes for a more efficient engine at all engine speeds- which usually translates into better fuel economy.
a fun experiment would be to destroke a 4.1 to 231 ci and see how it compares to a stock 3.8.

 

[cool 84]

the beauty of going with a motor with more cubic inches- even if you aren't looking to run 9's or something- is that it will be more drivable in day to day usage due to the extra torque. and a bigger bore almost always makes for a more efficient engine at all engine speeds- which usually translates into better fuel economy.
a fun experiment would be to destroke a 4.1 to 231 ci and see how it compares to a stock 3.8.

Eactly. The car is much more drivable for a given power level.

I originally went with the 4.1 because I didn't like the way the big turbo spooled on the street. It's a night and day difference now.

If you're doing a rebuild already, it doesn't cost any more money assuming you were going with different pistons anyway. I had mine bored .035" which gave it a 4" bore which means common Chevy pistons and rings can now be used. This gave me a considerable price break. For a street car I wouldn't think of building another 3.8L.

The first 4.1 block I found had cracks around the head bolt holes. The second was perfect and after sonic checking had a minimum .080" wall thickness.

 

[novaderrik]

which Chevy pistons do you use?
are we talking regular 350 parts here? 302? 327? 383?
i think those are all the 4" bore engines.
which rods would you use?

 

[cool 84]

which Chevy pistons do you use?
are we talking regular 350 parts here? 302? 327? 383?
i think those are all the 4" bore engines.
which rods would you use?

JEs but they're a Chevy slug and it saved me over $100 as compared to a JE piston for a 3.8L.

Same with the ring pack.

I used the stock rods.

 

[Jerryl]

JEs but .........

Welcome back!

 

[novaderrik]

JEs but they're a Chevy slug and it saved me over $100 as compared to a JE piston for a 3.8L.

Same with the ring pack.

I used the stock rods.

ok, but JE makes pistons for everything- so are we talking a piston for a 350 with a 5.7" rod, a 350 with a 6" rod or a 327 with a 5.7" rod?

 

[cool 84]

Welcome back!

Thank you! It's good to be back. I'm tired of the Acura forums to say the least. Got a nice tax return and I'm ready to fix the damage the bodyshop did. Almost got rid of it but hell, I've owned it since I was 17, went to my prom in it and now that I'm 31, it's my link to my youth lol.

 

[cool 84]

ok, but JE makes pistons for everything- so are we talking a piston for a 350 with a 5.7" rod, a 350 with a 6" rod or a 327 with a 5.7" rod?

Sorry, I was a little unclear. I gave them the specs for my motor, I didn't specify a certain Chevy. The rough forging itself is much more common in the 4" bore. I do think it was an off the shelf piston though because I had them within two weeks and they were over $100 cheaper than my set for the 3.8L. I wish I would've saved the box with the part# but that got lost years ago.

 

[Jerryl]

Thank you! It's good to be back. I'm tired of the Acura forums to say the least. Got a nice tax return and I'm ready to fix the damage the bodyshop did. Almost got rid of it but hell, I've owned it since I was 17, went to my prom in it and now that I'm 31, it's my link to my youth lol.

GOOD CHOICE!!!
Let me know if need anything.

Now back to: "Bigger is Better and runs harder and longer" :tongue: