brodix 11x vs. afr235 dyno test

[randy331]

Anyone care to discuss why the AFR heads didn't raise the rpm of peak TQ or HP?
Farmer how did the power curve before and after the peaks compare between the 2 heads?
What intake and carb?

Randy

[af2]

Anyone care to discuss why the AFR heads didn't raise the rpm of peak TQ or HP?
Farmer how did the power curve before and after the peaks compare between the 2 heads?
What intake and carb?

Randy

Yes!!! Finally!!!!! A post that I can relate to!!!!!! The exact same rpm the 2 heads came in at is not even close on a dyno or real world testing. There should have been at least 300 rpm difference all the way around!!!
Therefore Mr Farmer I call B.S.

Every post you have made since the first was to beat up everyone here!

Chad, I am bugging you again on the 235's!!!! It is winter

[MrBo]

Anyone care to discuss why the AFR heads didn't raise the rpm of peak TQ or HP?
Farmer how did the power curve before and after the peaks compare between the 2 heads?
What intake and carb?

Randy

Yes!!! Finally!!!!! A post that I can relate to!!!!!! The exact same rpm the 2 heads came in at is not even close on a dyno or real world testing. There should have been at least 300 rpm difference all the way around!!!
Therefore Mr Farmer I call B.S.

Every post you have made since the first was to beat up everyone here!

Chad, I am bugging you again on the 235's!!!! It is winter

Where do you get the 300 rpm difference from?

[JoePorting]

Both heads are too small for a 434. Both heads have a cross section around 2.8". A 434 should have around a 3.2" to 3.5" cross section. Nobody makes heads or manifolds that will provide max performance for a SBC over 410-420 cid. Think about what a 434 BBC would get head wise, then you'll have an idea of what I'm talking about. A 434 BBC or SBC have the same flow requirements.

[RichardThiessen]

Both heads are too small for a 434. Both heads have a cross section around 2.8". A 434 should have around a 3.2" to 3.5" cross section. Nobody makes heads or manifolds that will provide max performance for a SBC over 410-420 cid. Think about what a 434 BBC would get head wise, then you'll have an idea of what I'm talking about. A 434 BBC or SBC have the same flow requirements.

I learned this the hard way... had I known ahead of time I would have ran a shorter stroke and bought the proper heads the first time and just rev'd the motor higher.

[Tony Mamo @ AFR]

Anyone care to discuss why the AFR heads didn't raise the rpm of peak TQ or HP?
Farmer how did the power curve before and after the peaks compare between the 2 heads?
What intake and carb?

Randy

I agree....that is worthy of a discussion

But to be honest I'm not very surprised by that....or should I say I've attended many head/cam swap dyno sessions (with various manufacturers heads including some OEM stuff) and seen exactly the same trend. In fact one of the last test sessions I attended at Westech we swapped an AFR 195 head and picked up 40 HP with no other changes and the torque and power peaks were almost identical (but the fatter AFR curve also carried better past peak not rolling over nearly as quickly). At the time Steve Brule made the comment he has seen that situation many times before (and this guy LIVES on the dyno) where a better head just fattened and lifted the curve with little to no change in where it occurred (RPM).

A cam swap of course would change the shape of the curve (which IMO is more dictated by cam then heads) but in some respects its more impressive those gains came without added RPM because that means the peak torque and the rest of the curve must have fattened up significantly and the BSFC and VE of this engine improved dramatically. Also, achieving the big numbers earlier in RPM is certainly good for performance because that would indicate a big improvement in average power without having to rely on excessive RPM's to get the most from the combo.

I have to say, a bigger cam in this engine would have really made for some good Internet fodder....LOL

Seriously though....even another 10' would have been more than warranted here (while still providing good low/midrange figures) but may have fattened up the peak perhaps another 15-20 HP. As Joe stated earlier this cam is on the light side for the application in question....it's really light if your standing in Joe Sherman's shoes! More lift and more duration would have certainly allowed this combo to peak in the low/mid 7000's and made a good deal more power there as well (easily 750).

Also, these heads are very similar in size....I believe the actual pour volume of our 235 head is 233 cc's or so and the Shafiroff 11X head is 227 cc's (within 2% of the AFR piece).

BTW, these were not stock as cast 11X heads.....here is the info on this heads for those who missed it in an earlier post. They have some CNC porting and flow over 300 CFM ....

http://www.shafiroff.com/heads/brodix_11x.asp

-Tony

PS....OP, I think it would be helpful if you could post a layover of the dyno runs. Im sure many would be interested to see it myself included.

[user-9274568]

I think it's a no brainer why the peak was the same. Especially if he used the same manifold.

The 11x's I have measured have a 2.25 in² choke.

The AFR 235cc I just measured has a 2.53 in² choke.

300 cfm x 2.4 = 720 / 2.25 in² = 320 fps (Brodix head, .700 lift flow)

332 cfm x 2.4 = 796.80 / 2.53 in² = 315 fps (AFR head, .700 lift flow)

I might add this is calculated and an actual pitot will show more velocity on both. HOWEVER,

Same...

[af2]

Anyone care to discuss why the AFR heads didn't raise the rpm of peak TQ or HP?
Farmer how did the power curve before and after the peaks compare between the 2 heads?
What intake and carb?

Randy

Yes!!! Finally!!!!! A post that I can relate to!!!!!! The exact same rpm the 2 heads came in at is not even close on a dyno or real world testing. There should have been at least 300 rpm difference all the way around!!!
Therefore Mr Farmer I call B.S.

Every post you have made since the first was to beat up everyone here!

Chad, I am bugging you again on the 235's!!!! It is winter

Where do you get the 300 rpm difference from?

As in the peak should have been at least 300 rpm more with the same cam.

[randy331]

I think it's a no brainer why the peak was the same. Especially if he used the same manifold.

The 11x's I have measured have a 2.25 in² choke.

The AFR 235cc I just measured has a 2.53 in² choke.

300 cfm x 2.4 = 720 / 2.25 in² = 320 fps (Brodix head, .700 lift flow)

332 cfm x 2.4 = 796.80 / 2.53 in² = 315 fps (AFR head, .700 lift flow)

I might add this is calculated and an actual pitot will show more velocity on both. HOWEVER,

Same...

I don't see how adding .28" to the mcsa wouldn't allow the engine to peak at a higher rpm.
I realize on the flow bench the average speed at the choke will be the same if they flow the same cfm 2^, but on the running engine at the same rpm it won't be the same speed. That's why I asked what intake. I'm wondering if that was limiting the rpm.

Randy

[randy331]

A cam swap of course would change the shape of the curve (which IMO is more dictated by cam then heads)

Are you saying within a given head class? (23* sbc for example)

I know of engines making peak as high as 9500rpm with 270s cams, but with 15* heads.

And look at super stock 280+ to get a peak at 7500-8000 rpm, but small heads.

Seems this thread took a good turn.

Randy

[farmer]

"Every post you have made since the first was to beat up everyone here!"

I truly apologizes if thats the way it came across.

"Yes!!! Finally!!!!! A post that I can relate to!!!!!!"

Yes I agree a real question, and it appears a good Answer from Chad Speier.

I will post the complete dyno numbers in the morning i'll have to type them in because my scanner doesn't work. The reason we build these big engines for bracket racing is to increase reliability I build my cars to run a number even our top sportsman car is just a bracket car. We built sprint car engines in the 80's that made well over 700 hp these engines cost $30,000 plus and were far from reliable. I admire you guy's that are still out there looking for the last hp without you there would be no progress. I still like to swap parts with the best of them my altered needed to run 7.90's thats were we want to race the car so I gave this a try and I hope it'll be enough. There is a lot of improvements that can be made to this engine and I'd love to here about them but if my car runs the number I don't think i'll be doing anything else but tune it . My total investment in this engine is $8000 I think i'll get my money's worth.

[RCJ]

The first dyno was 684 at 6800 the second dyno was 677 @6800 after 185 runs.The question I have is what is a normal HP loss over the life of an engine.Would 185 runs degrade the valve job enough that some of the gains are from the new valve job.

[Carroll]

Note to self, never post any of your dyno findings.

Joe C

[af2]

Note to self, never post any of your dyno findings.

Joe C

Joe,
Laughing as I two finger type.

[MaxFlow]

I really think that there is information in this thread that is important. Why should there or shouldn't there be a 300rpm difference?

cross section alone based on piston demand? I think this engine needs way more than these heads can supply and for that reason I see no reason for a change. That's why looking at MCSA and where the peak numbers fall is misleading. supply and demand. Get the cross section/flow up there above supply side and you will start moving something. Then you'll start leaning on the boundaries for the combo. That's why there's no replacement for displacement if you have the air to move.