I need help understanding a few technical differences between cylinder head designs.

I've read the postings about our wonderful L03 heads and how much they suck beacuse of the swirl port design, but here's my question. What is that swirl port designed to do for the power band? If I understand it corrrectly it increses low end torque at the cost of high end power. Do the TPI cars have this design? My friend has an L98 IROC and he claims that he has swirl port heads which I don't believe because I didn't think the TPI cars had this design, is this true that they in fact do? And as far a Vortech heads go, from what I understand they are a variation on the swirl port design right? And if the swirl port makes more torque in the lower RPM band then for a 305/350 looking to make good power down low and high horsepower above 5000 wouldn't the Vortech heads be the route to go? If you look at all the newer motors from GM they seem to all be Vortech motors, why if that design is not good for power? Or am I misunderstanding this whole thing?

To swirl or not to swirl to make good torque and HP, that is the question.

I hope I didn't loose you in the like 18 questions up there but I need to settle an argument between myself and my friend with the IROC.

 

Yes swirl port heads are made for torque and no top end, but really if you put a set of 081 casting number heads (305 tpi heads) in place of the swirl port heads, you would have prob more torque and hp. The heads were designed to make more torque but actually they dont.Your friends car does not have swirl port heads, they only came on 305 Tbi cars, and as far as the vortecs being a swirl port variation, i have no clue, but they are one of the best flowing heads made by Chevy.

Kevin

 

TPI cars never had the swirl port heads.
Vortecs are not akin to swirl port heads, they have a very efficient
combustion design.
Swirl port heads can be modded to work pretty good, but not reccomended. (too much work involved) I did a set and picked up 40hp to the rear wheels but wouldn't waste my time again.

 

Does anyone have any pics of Vortech heads. What is it about these heads that make them so efficient? Are the World S/R heads even better?

Dyno Don you claim 40hp?!? What if I just put on 305 TPI heads and didn't port and polish them, what would be the result?

Thanks for the help guys.

 

The exhaust side is what needs the most work on all SB chevy heads (even World S/R heads). They all flow around 145-160 (read, should be 185 or more).

 

The swirl port heads were designed for trucks. They move the power band down significantly. If you notice how people say tpi produces a lot of low end torque, you will also notice how tbi's peak torque is even lower than tpi. This is due to the design of the swirl port heads. The torque peaks at a very low 2400 rpm on the L03, which provides good off the line power, but almost as soon as the torque peaks it drops off too.

 

I don't think the swirl ports are made to produce more torque down low, they're just supposed to increase efficiency.

Of course an increase in efficiency IS an increase in torque, but the objective wasn't to produce it in a lower RPM range. I think they just don't make any HP up high, so it's an illusion.

As someone pointed out, if you step up to a better head (like the Vortec) then you'll see an increase in the entire RPM range, not a loss in low RPM torque.

Regardless... sh*t-can them bastards!!!!

Either that, or put them in a truck like I am with mine.

 

I never understood this talk about the "swirl port" on our heads, until I took off my heads in place of some 305 TPI heads, then I got the picture. Its like having alomost half of ur intake port cut off with a UFO in it.

 

Thanks guys.

When the time comes for it I decided a long time ago to use the World heads on my car. I just wish I could get a 305 head that's aluminum. I've read in other posts about using the Twisted Wedge heads and adapting 350 heads but it's not worth the work for me, I like 'bolt on' mods. However, is there anyone who can offer testimonial about the Twisted Wedge heads on a 305?

 

GM has used swirl port designs for a while. I've seen them on 2.5 4 CYL's, and 350's. I think AJ is right, GM produced those heads cuz they wanted better air and fuel atomization when the mixture entered the chamber, kinda like those gimmick-a@s tornado things that say they add horsepower but dont do anything. I noticed when I replaced my LO3 heads with some unported 416's that the intake port looked alot larger on the swirl ports. I dont know what the flow capability but I would like to know. I wish someone could flowbench some of the more popular small block heads so that everyone could have a comparison.