InfernalVortex

iTrader: (4)

Guys I am just making winter project plans, and was looking at options for heads to go on my 355. I've had these Vortecs on there for years, and Im ready to move up.

I already have the intake, however, so while I am fine with going to a standard pattern head, it does save me $200-$300 to not have to get a new intake and new intake bolts etc.

I was going to get a set of Blueprint muscle series heads, I like the value of them, and the flow numbers are ... okay. For the money they're fine. But I just read they have a .500" raised exhaust port. I am pretty sure there's no way my Hedman long tube and exhaust system will tolerate that kind of move without serious interference issues, so I gave up on that.

I'll likely bump up the cam at the same time, maybe later, but I wont go too crazy. Probably an XR276. Might move these to a 383 sometime and go to a slightly larger cam, but still something streetable.

So i was looking at the AFR 195 and the AFR Vortec 190s:

https://www.airflowresearch.com/190c...cylinder-head/

https://www.airflowresearch.com/195c...cylinder-head/

It seems to me like the differences on the high end are tiny with streetable cams, and there is a slight advantage on the mid to low lift range. Is there any good reason to avoid the AFR vortecs beyond cost if you already have the appropriate intake?

Are there any other good bolt in options out there? I still cant believe those RHS heads have those raised exhaust ports. A half inch seems like a huge deviation to me and I doubt that will work out for me without some serious exhaust work.

Thirdgen89GTA

iTrader: (5)

No need for vortec if you are already going AFRs. I have the AFR 195's on my GTA. Glorious heads.

Orr89RocZ

iTrader: (20)

Gm bowtie small port vortecs are nice with a proper valvejob and blend the seat. Would consider them.

afrs are nice heads, something like an in between the 180-195 regular heads. Would make power but are pricey

Thirdgen89GTA

iTrader: (5)

For a budget yeah, good head. But to pay someone to get them flowing like the AFRs would probably end up costing you just as much as buying the AFRs to begin with.

If you can do the work yourself, its a no brainer.

Orr89RocZ

iTrader: (20)

Yeah maybe. The basic valve job and bowl blend is really all you need tho for a 276 cam and i assumed tpi but could be wrong there. They will move 250-260 cfm i believe like that and wouldnt cost to much to do.

But an afr out the box would do very well. They always seem to perform nicely.

InfernalVortex

iTrader: (4)

I would never profane my car with a tuned port. It’ll have a Holley double pumper of some sort on it.



To the other poster, I’ve already got the intake ( Performer RPM Air Gap) so I’d have to spend money to get a standard one. But I think a single plane may be out there that will fit under a stock hood for standard heads so there’s that...

Thirdgen89GTA

iTrader: (5)

if you go 195s they won’t hurt performance over a 180cc runner. They can outflow a 350. I doubt you’ll rev high enough where a 195 would be a restriction.

skinny z

How likely is this? While it's not a lost cause putting a smaller head (like a 180) on a 383 certainly the AFR 195's are going to let you make 500 HP if you've got the rest of the supporting parts and engine spec. That isn't entirely likely to happen with the Vortec or the RHS Vortec upgrade or anything else similarly sized unless you have enough RPM. I can tell you that there are examples of the small headed 383 and the right spec cam providing excellent results. Especially for a car that sees a lot of street time.
As for the 350, a 276 and a ported Vortec or similar aftermarket head will push 3700 lbs to 109 mph in the quarter. Not entirely sure of the math on that but it gives you an idea.
But...If I were to do it all again, I'd go right to the AFR 195s regardless of the cubic inch.

Orr89RocZ

iTrader: (20)

Performer rpm and 195 head would be it imo. Good 276 cam lobe on a 108 or so let it eat

skinny z

Looking at it from my pile of parts (in as much as I'd like to have picked up a set of the 195s before I invested money in my RHS heads), I'm looking at an interesting approach posted by Vizard. One of his dyno examples has a 383 with Edelbrock's Performer RPM 170cc head. Here's a section of the text from his article.

"...a set of angled-plug Edelbrock RPM Performer 170cc heads with 70cc combustion chambers was installed on our 383. For the first round of testing, we would run with the smaller of two COMP Extreme flat-tappet hydraulic cams we had for the project. This first cam was a custom 270/274 (226/230 @ 0.050) dual-pattern cam on a 106 LCA that, with the COMP rockers of 1.6:1 intake and 1.5:1 exhaust, delivered valve lifts of .514 inch and .488 inch, respectively. With all else the same as for the last test the engine, the short cam and Edelbrock heads (green curves in the Dyno Test No. 3 graph) delivered outstanding low-speed torque. The lowest we could pull this combination down (a limitation of the SuperFlow dyno) was 2,800 rpm, where it made more torque than our baseline 350 did at peak torque.
The next move was to install the bigger COMP cam, which specs out to 284/288 of seat duration and 240/244 @ 0.050 on a 106 degree LCA. Lift on this cam was .541 on the intake and .503 for the exhaust. As predicted, the bigger cam/small-port combo did not lose as much low end as might have otherwise been expected. The torque at low speed was indeed on par with the bigger port Iron Eagle combo that used a smaller cam. Peaks were 484 lb-ft and 459 hp. This just goes to show there is always more than one way to skin a cat. This time around, the smaller-port heads with the bigger cam produced about 4 hp more than the bigger-port Iron Eagles with a smaller cam, the only difference is that with the Performer RPM heads, it was done on a lower compression ratio (9.7:1)."

Interesting build direction I thought. And one which I'm entirely likely to follow. Speccing the cam will be the critical part.

Fast355

iTrader: (2)

I like the concept but what the testing done on the dyno at WOT does not show is how much more tame the small cam/large port engine will be at lower rpm. The idle will be lower and smoother. The engine will make more off-idle torque. It will also allow you to run in higher gears at a lower rpm. I'd give up the slight difference in power to have better manners overall.

skinny z

Here's the thing about that. (And it's easier to copy the relevant parts of the engine build paper than it is to put it in my own words.)
So..

"... a set of angled-plug Edelbrock RPM Performers (PN 60719) with 70cc combustion chambers was installed on our short-block. For the first round of testing, we would run with the smaller of two COMP Extreme flat-tappet hydraulic cams we had for the project. This first cam was a custom 270/274 (226/230 @ 0.050) dual-pattern cam on a 106 LCA that, with the COMP rockers of 1.6:1 intake and 1.5:1 exhaust, delivered valve lifts of .514 inch and .488 inch, respectively. With all else the same as for the last test the engine, the short cam and Edelbrock heads delivered outstanding low-speed torque. The lowest we could pull this combination down (a limitation of the SuperFlow dyno) was 2,800 rpm, where it made more torque than our baseline 350 did at peak torque. Such is the advantage of cubes. On the street, an engine like this in an otherwise stock Camaro would be a tire shredder for sure. With a manual trans, this engine could accelerate at least as briskly in Fifth gear as a stocker would in Forth gear. With an automatic trans, the car would leave hard without the necessity of a lower gear or a high stall converter, both of which would impact mileage" So that's a small port with a 226 @ .050" cam."

Agreed. Plenty of low engine speed torque but..

"The next move was to install the bigger COMP cam, which specs out to 284/288 of seat duration and 240/244 @ 0.050 on a 106 degree LCA. Lift on this cam was .541 on the intake and .503 for the exhaust. As predicted, the bigger cam/small-port combo did not lose as much low end as might have otherwise been expected. The torque at low speed was indeed on par with the bigger port Iron Eagle combo that used a smaller cam. Peaks were 484 lb-ft and 459 hp. This just goes to show there is always more than one way to skin a cat. This time around, the smaller-port heads with the bigger cam produced about 4 hp more than the bigger-port Iron Eagles with a smaller cam, the only difference is that with the Performer RPM heads, it was done on a lower compression ratio."

I've placed in bold the argument regarding the "manners" part. Seems like it's a cake and eat it too kind of deal. I see I've basically reposted what I had done earlier although I wanted to put an emphasis on the small head/big cam torque characteristics. The advertised specs of the cam notwithstanding, it's the overlap realized that makes or breaks the idle quality as well. This bigger cam has an overlap of 74 degrees (.050") which when compared to the XR288HR at 71 degrees isn't too far off. I can tame the 288 easily enough and I've published numbers to show for it. That said, I might try a little smaller cam for my own application to try and reduce some of that tuning. Remember I've no electronic controls. Strictly old school.
Here's a link to the entire article if anyone is interested.

https://www.hotrod.com/articles/0703...z-engine_build

Orr89RocZ

iTrader: (20)

That bold statement was refering to wot at 2800+. Now i would have expected some torque loss but not necessarily alot. But idle and part throttle drive/cruise at say 800-1600 rpm may be very different. Also note vizzard did a stock oem vortec head 355 build with a 224/224 108 hyd roller that made 447 hp. So it would seem either of those heads were not much better than stock vortecs. And 383 didnt help much in power but did in torque. And ported iron eagles they used were bad ports or just way too big and killed cyl fill

skinny z

I would say part throttle and idle would be more a function of tuning rather than anything else. And timing is everything it seems. As I pointed out, the overlap isn't to far off. Then again, I will concede that the 3 extra degrees may be a significant bump. The IVC is 102 as well.
Interestingly, the paper in full (link above) is using the Vortec 355 you've referenced (Sledehammer) as a baseline for $ to HP/TQ (such is the nature of magazine builds). I can't really comment on the Iron Eagles. I do understand they respond well to porting although the test heads are out of the box.

Fast355

iTrader: (2)

That build was a stock Vortec short block. It had EQ Vortec heads with larger ports and 2.02/1.60 valves that flow much better than the stock ones do. Given the same cam and heads a 383 will not build much more HP than the same parts on a 350 but drastically increase the torque. Same thing would happen if you pulled the cam and heads off a 383 and put them on a 400.

Orr89RocZ

iTrader: (20)

I must have misread stock heads for stock shortblock. Either way with oem type relacement heads, they arent all that much better than stock vortecs that have a refresh and good valvejob.

and if the heads and intake flow more than the engine is demanding, you should see abit more hp like you said using same parts on longer stroke as the cfm demand would go up with the faster piston speed but rpm range does move down. Faster demand earlier should make more torque earlier.
Look at the early gm 4.8/5.3. Different stroke, same heads cam and slightly more power to the 5.3. 15-20 hp or more depending model rating. 4.8 255-280 vs 275-295 hp 5.3

skinny z

Keep in mind here is that, at least from what I'm interpreting from that small head build, is that it's the flow velocity rather than the flow amount that's helping with the higher torque production. What the AFR, or in this case the Iron Eagle, hasn't got over the Edelbrock 170cc is the effect from the higher velocity aiding with cylinder filling. Exactly what was alluded to earlier with the Iron Eagle heads lacking in that regard. It's this boost to volumetric efficiency that allows the larger cam to perform where normally it wouldn't. Also, there's the other side to this and that's the lower than optimum compression ratio. I couldn't imagine running a cam as large as that with 9.7:1. Cranking compression (or DCR!) wouldn't be what you'd be going for with a more traditional approach. But this article, at one point, became biased towards a regular grade pump gas engine.

Orr89RocZ

iTrader: (20)

thats basically a turbo motor without the turbo. Def not optimal but they still make power to be fun. Also tuned a 280 xfi 350” motor that was around 9.8 to 1. Ran good but def wanted more converter stall. Soft under 3800 ish

yeah thats part of it. Who knows the complete picture tho. Whats the floor speed vs middle vs top of the port? Is it relatively uniform or all over the place? Whats the areas? I will say afr has been known for higher velocity as well, being targeted more for street builds under 6500 ish rpm.

skinny z

Just saw this question in the first post. I think it's reasonable, based on what's come out of this thread, to say that the AFR Vortec will do a fine job. Considering lesser heads still yield good results, the AFR would certainly be a step up. I would like to see flow numbers for them though other than what AFR posts on their web page. I don't recall seeing them in Stan Weiss' web page database.

Thirdgen89GTA

iTrader: (5)

Actually, looking at the current get AFR Vortec 190cc heads, they flow roughly about the same on the intake, and are only a few CFM behind the 195cc street port head.

Unless comp port, I'd say go with whatever is cheaper at that point then.

I made the mistake of thinking GM Vortec heads vs AFR 195 SBCs early on, that's my bad for misreading.