Hey guys,
I'm building a 383 for my 91' TA and looking for a set of heads. I'm looking at a set of Patriot Performance heads and Blue Print heads.

http://www.summitracing.com/parts/MLL-H8002K/

http://www.summitracing.com/parts/PAR-2168/

I'm running a LT4 hot cam with 1.6rr. Im trying to build the engine close to what and LT engine would be and the Blue print head flow 195cc on the intake like the LT heads but i've head a few people tell me that its a to big of a head and would slow me down on the bottom end and suggested the Patriot Performance head that flow 185cc intake. What do y'all suggest? I'm leaning towards that blue print heads myself.

 

I believe the larger your intake runner the lower your RPM power band will be... I think. Not an expert by any means, but if that holds true, you'd be generating more power (torque) in the lower RPM ranges which, if logic holds true, should give you a quicker bottom end performance. Your upper end performance would suffer, however.

I was looking at 195s as a compromise between the options. It is pretty much in the middle of what is sold, so I'd imagine it would be the most balanced option.

Keep in mind that every time I fix something on my IROC I manage to break two other things, so, take my advice with a grain of salt. I just like typing and problem-solving with others. :-)

 

The runner size doesnt necessarily effect the power band. An intake runner is only capable of making X amount of hp, it will make that regardles of the cu of the motor. The cu affects at what rpm it will make that hp. On a 350 a certain head will make peak power around say 7000rpm, same setup with a 383 it will be around 6500, on a 400 it will be around 6000rpm. Those aren't specific numbers just wanted to give an example.

Ideally you want to use the smallest sized runner that will make the hp you want in the rpm range you want.

-Jim

 

383 will want more air. I suggest at least a 200CC head; preferrably a 210-215. Runner length is not necessarily as important as overall design of the runners themselves. On general, though - I'd say go with a 210 for a 383 so you don't starve the motor for air up top. 185cc's is WAY too small. I run a 200cc head on my 355. You could go with a 195 assuming you got a quality head, but since the price between the two is identical.. just get the 210-215 and be done with it.

 

It really depends on the cfm the head flows, and the desired rpm range. The LT4 hot cam isn't a high reving cam and the 383 cubes are just going to lower the cams effective range more. If you want to stick with that cam I would suggest a smaller runner head. What intake do you plan on using?

 

I'm using an Edelbrock air gap 1,500 6,500 rpm range and the cam range is just inside the intake rpm range on both ends.

 

Interesting question, I know I used the Dart Pro 1 200cc heads and a Comp Cams XR282, and honestly I thought my 383 was more of a torque engine than a high rpm screamer. I ran a 7.42@92mph 1/8 time, 1.67 60'

My combo back then:
383, flat top pistons
Dart Pro 1 200cc heads (64cc chamber)
Performer RPM Air Gap
XR282 - 230/236 .520/.540
Holley 750 "double pumper"
TH350/TCI Streetfighter convertor
Ford 9" with 4.11's.
Hooker 2210's (1 3/4 primary, 3" collector)

The car ran great for sure, but always felt "undercammed" or maybe "under-headed" to me personally. I actually changed to a larger duration/lift Comp roller and was much happier, more power all around. I still believe getting the best head you can buy for the money, with the most flow capability is the way to go. Now that I'm in the "LSX world", there are people putting 226cc ported heads on a measly LS1 (346ci) and making bonkers power everywhere. I mean, 350lb ft of TQ at the rear wheels at 3000rpm, and going up from there. So either the LSX head design just promotes better cylinder filling and velocity, or the old "smaller head for TQ" argument has become outdated. I just don't know.

 

Lsx heads are a bit different from sbc heads mainly because of the 15 vs 23 degree heads. Then there is the port shape...

 

The difference is more in the design if I am not mistaken. The ports are longer and narrower so they can have higher volume yet the narrow design still promotes higher velocity so it doesn't feel lazy off the line. Best of both worlds.

 

The LS2 and up uses a huge rectangle port design like the sbc or even bbc. The small thin semi tall ports just hold back power which is y the ports went back to a better/ old design. Another reason they used the narrower ports was for pushrod clearance.

The valve angles do help a lil bit (real Pontiac motors had 12-15 deg heads on all their motors back in 1955 glad to see its such a "new" thing) but if you put bigger heads on a sbc your going to make more power, don't limit yourself by putting small stuff on it. Soo what if you loose 10 even 20lbft under 2500rpm, spining tires is fun but really thats y the upgraded gears get put in..
I had 210s on my ole 350, im now runing AFR 235s on my 400 stroker and wish they a were bigger..

 

Well guys these are the heads I decided on, http://www.summitracing.com/parts/PAR-2181/ They seem like a good set of heads for a street/strip combo. we'll see how they do.

 

Anybody got experience with Jegs or Summit brand heads?

 

bump*

 

How can so many of you be so confused? Look, huge ports kill low-RPM torque. Huge ports don't guarantee more flow. Flow is what you want, not huge ports. The smallest port that flows the best will get the best results. When a street-cammed 400 with a too-small carb can do 525 HP at 6500 RPM with a good 180 cc head, why would you even consider anything larger on a lesser engine? And Ttop 350 is way wrong. The LS2 was still cathedral-port, thank GM. The LS3 failed with the too-big rectangular ports, which always hurt power below 4000 RPM. Every single comparison test ever published proves it. The port is too big for the flow. AFR has cathedrals that outflow the LS3 head with far less port volume, and even MAST's Black Label rectangular ports have smaller port volume while far out-flowing those LS3 disasters. Also, you can't compare LSx port volumes to SBC port volumes, due to the LSx using more runner length in the heads. Lingenfelter proved his favorite claim: It's not peak HP, it's how much power you make at the upshift recovery point. So trying huge heads for a bit more topend is silly. You go right past the point of diminishing returns. Never give up more in the midrange than you gain back at the top end.

 

You can't just say that "certain head size _____ is too large" because every cylinder head is different in the aftermarket world... along with how the runners are designed to manipulate airflow. What if we had a 195cc or even a 205cc in it's place of the 180? You probably just gained another 15-25 cfm's and can take advantage of every bit of it with 400 cubes.. which equates to quite a nice power gain. It's like walking into two different clothing stores (for women) and saying "Well, they both say Large so that must mean they're the same!" Not that easy. It's about average airflow (and NOT peak) - if I can achieve greater averaged velocity numbers with a larger port, then I'll happily take that. It's also important to note that there is such a thing as too MUCH velocity based on runner design.

Comparing LS style heads isn't even is the same league. Their angle/port design changed things completely; allowing the ability to go to a much bigger cylinder head without suffering from it like you would with a standard 23 degree. If there wasn't any power to be gained from it then you wouldn't see so many people running them.. especially with how much of an aftermarket there is for stock cylinder heads at places like Ai and Lloyd Elliot.

You're not going to lose any noticable bottom-end in a 383 with a well designed 215 cylinder head.. Maybe a Procomp you will, but you get what you pay for.

 

Thats what I said two months ago lol

 

Delta it's not that a certain head size is too large, you want that head that has the best flow at the smallest runner size. Brand x's 215s may flow 280 @ .550, when brand y's 190s flow 280 @ .550 as well. They both in theory will make the same power but brand y's would have better torque/driveability.