[MT66]

I'm a bit surprised as Straub has a cam specifically designed for the AFR 265 heads. To me the engine is overcammed and the dyno seems to prove that. Why run a solid roller if the plan was to only go to 6000 rpm in the first place? It's still climbing at 6000. A nice hyd roller seems like it'd be a better choice.

Even if the cam is too big, the AFR 265s are a mega efficient head and a small port for a 496 so I'd have expected a lot more torque. It feels like something isn't quite right.

If you put on a dual plane im sure that'd pick up a lot, but that may not solve a potential underlying problem.

Not sure if it's specifically designed for the 265's I think he ground it according to my build. Solid roller was my choice, I realize hydraulic would work just fine. I just wanted solids.

I agree with the low TQ #'s I was expecting a fair bit more.

The operator said several times that he has a very conservative dyno (whatever that means) so maybe it's just that?

 

[MT66]

Mufflers are probably contributing some to the low numbers. Unfortunately you don't know much power or torque they killed. Did you have an air filter on it? Electric or mechanical water pump on the dyno?

Filter is in his air supply system in the ceiling. It's pulling room temperature air from main space of his shop. Electric water pump was used. Yeah I'm kicking myself for not doing a pull without mufflers just to see if there would be a difference.

 

[Steve69SS396]

Not sure if it's specifically designed for the 265's I think he ground it according to my build. Solid roller was my choice, I realize hydraulic would work just fine. I just wanted solids.

I agree with the low TQ #'s I was expecting a fair bit more.

The operator said several times that he has a very conservative dyno (whatever that means) so maybe it's just that?

The dyno my engine was on was also noted as stingy. My observed numbers were actually higher than the corrected numbers. The correction factor took power away, which was disappointing.

 

[shovelrick]

I’d try a air gap dual plane and a 1” open spacer before you put it in the car, I realize no more dyno time, my 489 dyno sheet pic is in my media and that’s with a mild shelf hyd. roller 231/239 cam I picked for air cond., 1,000 HP and air gap & 1” spacer on 91 & 93 non eth gas, open 1 7/8” headers

 

[MT66]

I didn't get a print out of the observed #'s but they were lower than corrected so it's not likely the dyno. They fella that dynoed it, is my machinist who did all the machine work. I assembled the engine. I had to beg him to run it on the dyno because he only uses it for engines he assembles. He has some very good reasons for this and I feel lucky he did for me. So making adjustments and getting it on the dyno again is most likely out of the question.

 

[MT66]

I’d try a air gap dual plane and a 1” open spacer before you put it in the car, I realize no more dyno time, my 489 dyno sheet pic is in my media and that’s with a mild shelf hyd. roller 231/239 cam I picked for air cond., 1,000 HP and air gap & 1” spacer on 91 & 93 non eth gas, open 1 7/8” headers

That's more what I was expecting my curves to look like. ALL TORQUE. Very nice

 

[shovelrick]

That's more what I was expecting my curves to look like. ALL TORQUE. Very nice

I kinda wish the dyno started a little lower in RPM and that was after 5-6 pulls and only turning the dist by ear, no carb tuning ( was a swap labor for labor kind of deal) so limited dyno time

 

[BillK]

I would be a little disappointed but I dont know what the mufflers did to it. This is a 496 I did a few years ago. 10 1/2 to 1 "No name" aluminum heads. Rectangular port manifold on oval port heads (dont ask) 1050 Dominator. The cam was a hydraulic roller that I am pretty sure was smaller than yours. I have the specs at the shop. I told them not to take it much over 6K and you can see it was still climbing there as far as HP.

 

[MT66]

I would be a little disappointed but I dont know what the mufflers did to it. This is a 496 I did a few years ago. 10 1/2 to 1 "No name" aluminum heads. Rectangular port manifold on oval port heads (dont ask) 1050 Dominator. The cam was a hydraulic roller that I am pretty sure was smaller than yours. I have the specs at the shop. I told them not to take it much over 6K and you can see it was still climbing there as far as HP.

View attachment 760576

Wow.... similar builds but night and day difference in peak#'s
Thanks for that info Bill.

 

[MT66]

So is there anyone out there that has done back to back testing with and without mufflers on a similar build?

. This has now got me really curious and hoping that my less than stellar numbers are due to the mufflers.

 

[71malibuu]

I don’t see mufflers being worth 50hp. Have you called Chris and gone over the results? I’m sure he’s camd dozens of 496s with those heads and similar compression…..what’s the normal expected result? Looks like a great cruiser but I agree that with the parts involved I would be expecting another 50 hp and more tq. The definite test would be mph at the track…. I tend to believe the mph out the back end over the Dyno hp numbers in many cases.

 

[MT66]

I don’t see mufflers being worth 50hp. Have you called Chris and gone over the results? I’m sure he’s camd dozens of 496s with those heads and similar compression…..what’s the normal expected result? Looks like a great cruiser but I agree that with the parts involved I would be expecting another 50 hp and more tq. The definite test would be mph at the track…. I tend to believe the mph out the back end over the Dyno hp numbers in many cases.

Yeah I didn't think so either on the mufflers.
We did the pulls on Thursday and I was off grid yesterday so I haven't had a chance to check Chris's thoughts. I plan on doing that Monday. Chris nailed my goal and then some on the hp. I asked for 600 and it would've likely pulled to the 620s if we had kept going.
From all the reading I've done here and other forums, mid 600's for both torque and hp is kinda the norm, haven't seen many TQ #'s below 600. I'm not questioning any of the parts specifically (other than the single plane) I just wanted check you guys for thoughts on the TQ. Just seemed like it should be closer to the hp.

It will make for nice street car and I shouldn't be too embarrassed at the strip. Overall I'm happy with the results, it's just my nature to question if anything was left on the table. I'm really anxious to get the car done and on the road this year!!

 

[Flounder68]

As for the mufflers, Engine Masters did an episode where they did a muffler shootout on a 1000hp motor. Here was the results of the straight thru and chambered Flowmaster. Not a whole lot of loss on this engine.

 

[MT66]

As for the mufflers, Engine Masters did an episode where they did a muffler shootout on a 1000hp motor. Here was the results of the straight thru and chambered Flowmaster. Not a whole lot of loss on this engine. View attachment 760588

As for the mufflers, Engine Masters did an episode where they did a muffler shootout on a 1000hp motor. Here was the results of the straight thru and chambered Flowmaster. Not a whole lot of loss on this engine. View attachment 760588

Well that's pretty damn negligible.
Thanks for posting that.

 

[VORTECPRO]

Not sure if it's specifically designed for the 265's I think he ground it according to my build. Solid roller was my choice, I realize hydraulic would work just fine. I just wanted solids.

I agree with the low TQ #'s I was expecting a fair bit more.

The operator said several times that he has a very conservative dyno (whatever that means) so maybe it's just that?

Either the dyno is calibrated or it ain't. He's what I see the: the dip is from starting the pull, theres no problem there. Now the numbers, Cody sits @ 4900 feet elevation, you have a 474 observed HP engine there. Even before the correction is applied your down some HP, but not a crazy amount, the TQ was destroyed partly from the single plane intake, which you would never run @ 5000 feet elevation, especially with a 3.08 gear. Now back to the dyno, there can be a lot of problems with peoples dyno cells, I can tell you all about that. Maybe he's using SAE correction as well, do you have more data?

 

[VORTECPRO]

Ok......I looked at your conditions page, all that looks correct to me, did he inter your bore and stroke?

 

[MT66]

Either the dyno is calibrated or it ain't. He's what I see the: the dip is from starting the pull, theres no problem there. Now the numbers, Cody sits @ 4900 feet elevation, you have a 474 observed HP engine there. Even before the correction is applied your down some HP, but not a crazy amount, the TQ was destroyed partly from the single plane intake, which you would never run @ 5000 feet elevation, especially with a 3.08 gear. Now back to the dyno, there can be a lot of problems with peoples dyno cells, I can tell you all about that. Maybe he's using SAE correction as well, do you have more data?

That is all of data I have at this time. I had asked for a file to be emailed in a format that I would be able to open. He is going to try and figure that out on Monday.

I would assume he entered those specs when he was setting it up. He had the engine for 2 days and I asked if he would call me down to his shop when he had it broke in and tuned for some final pulls before I picked it up that day. So I only caught the tail end of everything. I'll see what he turns up Monday if anything and post it here.

I was really hesitant to use the single plane for this build, but that is what was recommended. As I mentioned earlier, I have to pull it anyhow, so it WILL be replaced with a dual plane of sorts. Any recommendations on one in particular?

 

[VORTECPRO]

The correction factor and Barometer looked good to me. Air gap intake.

 

[-SS454-]

Not sure if it's specifically designed for the 265's I think he ground it according to my build. Solid roller was my choice, I realize hydraulic would work just fine. I just wanted solids.

I agree with the low TQ #'s I was expecting a fair bit more.

The operator said several times that he has a very conservative dyno (whatever that means) so maybe it's just that?

I just mean Straub designed a cam that is 235/235@.050 made for AFR 265s if my memory is correct. It is a Hyd Roller focused on a 454 platform I think. If you had 8 degrees for being a SR, that'd put it at 243/243. A 260/268 is like a 252/260 Hyd Roller. That's a hefty cam. He must have had a reason to select what he did I guess.

There are definitely stingy and happy dyno's out there. But that should only affect the overall numbers. The curve should still be the same, and your torque curve is just not one would expect.

Aside from changing the camshaft, the best thing you can do is change to an air-gap and you likely will pick up 35+ ft-lbs of torque in the mid range. I wouldn't be surprised if you picked up more than that in the low end.

 

[Harris Roc Malouda]

The AFR is a good full point too lean. Did it make best power at that AFR? I would expect more torque also. Ten years ago my 427SBC made 640HP and 565 torque with a set of AFR210 head that I purchased in 2000. A 496 should make better torque than that. What fuel and how much timing? How well did the intake ports match up to the heads?

what would you consider the best AFR for power? To me 12,x range is pretty much perfect..