It is not good to lug a motor. Theres no reason to run wot below 2500 rpm imo. Converter and or downshift your engine will love you more

 

You can start the pull anywhere you like but with an auto everything below the converter stall is meaningless.

GD

 

Tell that to the tow truck operator.
I guess it's a question of semantics at this point. I wasn't necessarily speaking of WOT at 2k. Just more about torque production. Sort of like being in converter lockup in OD on the highway. Although with GD's combo, that doesn't apply here.

On a similar note, Vizard has just posted about valve seat angles and the significance of low lift flow. He's put a lot of effort into demonstrating what works and what doesn't. He's even gone so far as to develop trick valve seats to enhance the results. It makes me wonder that if what happens at .050" is of little consequence, then why pursue it? I've asked for some clarification although I doubt if a peon like myself will get a reply.

Unless of course, as stated above, you're in a situation with the converter locked up in OD on the highway. I know that's not a situation you'll be in. For me, it was very much the case.
Anyway, just saying.

 

The converter would unlock as soon as you tipped into the throttle. The dyno can't really measure steady state power. It can apply a load, which is useful for tuning, but without going to WOT, you won't be able to measure what the engine is actually capable of producing. I don't think the converter clutch would handle WOT power - it's not designed to do that. Would likely burn it up.

My converter and my trans are non-locking so it's not possible for me to attempt that anyway.

GD

 

sorry to say a dyno is a wide open throttle device lol never known a tow truck to go wot off idle either. Lugging is harmful

drivability and feel at lower rpm lower throttle openings is a different thing all together. Im sure you could get a reading of some sort if you 1/4 throttle accelerate but not sure how accurate or meaningful it is. If a load bearing steady state dyno you might beable to compare builds better, seeing how much force it takes to hold a motor back at low rpm low throttles but again i dont know how meaningful this is

 

Rhoads V-Max lifters make a little more noise but make a massive difference in low-speed, off-idle torque as well as idle quality. 218/228 @ 0.050, 110 lsa cam, 106 ICL with 0.578 lift from 1.7 rockers in my 11:1 383​​​​​​. Idles at 750 rpm with 4* of timing advance with 16 in/hg. 4* initial timing, 26* total at 3,000. Ran on the stand with a carb. Have not even touched the idle mixture or speed on the Edelbrock 1406 600cfm carb that has been sitting on the shelf 3 years since it came off a 5.3. Would have idled better dialing in the carb and running a vacuum advance but the carb is about to come off and EFI about to take its place. Only ran it to check for leaks and to hot lash the valves before it gets dropped back into the tan Express van sitting in front of it.

Microphone on my phone is picking up the valvetrain about 2x as loud as it is and the exhaust about 1/2 as loud.

 

Looks like the Rhoads lifters are flat-tappet only. Being a roller engine those wouldn't be suitable for my application. Looks like an interesting technology though.

I actually just ordered a new set of Johnson lifters for it. The 2110 LS style units. Apparently GM did a bunch of testing on these and they won the day. Used by GM in the 2014 COPO Camaro.....

GD

 

Mine are roller.

That being said Johnson makes great lifters too especially their high lift line.

 

Well, I did get a reply.
A little feedback from David Vizard regarding the Vortec vs AFR comparison. This is lifted from a post I made on DV's Speed Talk thread regarding valve seat angles.

My question:

David

To assist with a conversation I'm having with a fellow enthusiast regarding a comparison of two cylinder heads, can you explain why you place such emphasis on low lift flow?
Case in point: Vortec vs AFR 195. My opponent is stating outright power results. I'm talking about efficiency in general.
AFR doesn't publish flow data less than .200". The Vortec's forte appears to be what happens between .050" and .100".
Who is the leader here in terms of low RPM torque production / VE?

Thanks in Advance.

Kevin

DV's reply.

It is a little scary to give an absolute answer here but I would say that the Vortec head has a slight advantage at low rpm and possibly mid range. after that superior airflow of the AFR heads wins out.

DV


Anyway, after all of that, if I had to choose between those heads for what I'm building, I go for the AFR's in a heartbeat. But it's not necessarily the best choice all around. I believe in another thread it's just been stated that the 195's are 383 territory (since edited).

https://www.thirdgen.org/forums/tech...too-large.html

Or by extension, a high winding 355. You can easily make power north of 6500. This isn't to say the 195's are the wrong choice for 350 CID, but their full potential remains untapped.

 

I played with the valves a little more (getting better in technique again like I once was) in the current 383 setup, hooked up a vacuum advance and got it some decent idle timing. It is idling at 24° timing advance now rather than 4°. I varied the idle timing from 20 to 30 and it seems to like 24-26. Now makes 210 psi cranking compression in every cylinder. Stock GM Vortec roller lifters with 1/4 turn lash gives 195 psi in the cylinder I checked. With the Rhoads lifters hot lashed to 0.020" it makes 19 in/hg vacuum at 700 rpm and 24 in/hg @ 2,500 rpm with no load. A throttle snap on the primaries to just before the secondaries open results in very quick throttle response and the vacuum holds at 10 in/hg. It is scary how fast it revs even with a carb. With a 600 cfm 1406 edelbrock it is super responsive. 40 psi oil pressure at hot idle with 5w30.

Out of emissions necessity for visual inspection, I am going back to the L31 truck manifold. Heavily ported with an E85 compatible 48 lb/hr fuel spider and having to re-enable the EGR atleast for inspection purposes. I am hoping it might be a little more fuel efficient as well with the spider spraying directly on the back of the intake valves rather than the intake port floor like it does on the marine intakes. If it gets better MPG with the EGR will probably leave it enabled as well and then use GM top-clean before every oil change to keep the oily, carbon out of the plenum. At 2,850 rpm @ 70 I am sure a little EGR could help cut the pumping losses and drop the cylinder temps in lean cruise without making a noticeable power loss.

Leak down test, short block has about 15K on it so far. Every cylinder was practically identical. With the Marine dual plane MPI intake and a 232/244 @ 0.050 cam this engine has already pulled my travel trailer from Fort worth, Texas to Durango, Colorado and back without missing a beat. The smaller 218/228 cam has more grunt in my normal RPM range.

 

So I got the AFR heads and the gasket recommended by AFR for installation of said heads and I ran into an interesting bit of information with the included instructions on the new Fel-Pro gaskets.

They say in the instructions that came with the new Fel-Pro gaskets that there have been revisions to the gasket coolant port sizing due to the propensity for the gaskets to fail between the center two cylinders (exactly what I experienced) because of the center cylinders having the exhaust valves being adjacent to each other.

In conjunction with my ignition timing malfunction - which locked the timing to 10 degrees all the time, I think the lack of coolant flow between the center cylinders and the timing malfunction is likely responsible for the failure I experienced.






​​​​​​
GD

 

1. Does that mean your Vortec heads are still good? (Because David Vizard does have a video on how to port them in YouTube.) 2. Regarding the discussion on cams. Before David released his Torque Master program, he explained his cam theory in this article (which was originally found in Popular Hot Rodding before Hot Rod bought them.) It's repeated in his How to Make Horsepower book. The Street Strip button targets an overlap value between 50-75 degrees. https://www.hotrod.com/articles/0607...mshaft-basics/
3. Regarding your inputs in the Torque Master Program, you should be changing the intake length and targeting the 3rd wave as that is just the Helmholtz Equation. It should change the peak HP and peak TQ RPM below where you enter the wave. There is a post about it and calculator here: https://www.thirdgen.org/forums/tpi/...culations.html
4. In regards to which cam to use....David Vizard actually had his own line of cams that Lunati ground for him. The part numbers are in his How to make Max Chevy Horsepower (the 2009 edition) book. Or here: http://www.motortecmagazine.net/a-ne...ms-speed-spec/
5. Yes use the 1.6 rockers.
6. Yes the Vortecs have better low and mid than the AFR's. However....here's an AFR 195 TPI Build. I had to email the builder Greg Lovell to get the final numbers as that was never posted. The reply: "That 383 has been finished and run on the dyno. The TPI runners had to be ditched due to vacuum leaks that could never be sealed. With stock runners the engine made close to 400 hp and 425 tq. I do not remember the exact figures as we ran that engine many months ago. There is a lot of power left in that engine once the TPI gets removed and a sensible manifold gets installed. Costs on this engine were not kept track of by us. The author kept track of everything." Although Dyno Don has a wonderful AFR Combo.
http://www.superchevy.com/how-to/eng...oject-top-gun/
7. Everyone knows about the crappy flow numbers from the SDPC base right? There is a sticky: https://www.thirdgen.org/forums/tpi/...pi-intake.html
8. Those are really good numbers for a Vortec TPI. That has to be because of the FIRST Intake. Compared to an older Vortec build. https://www.thirdgen.org/forums/afte...i-dyno-12.html
9. I noticed that you aren't running a cold air system. With that filter at the front of the intake, it will get heat soaked pretty good without it.
10. Good job! Sorry to hear about the head gaskets. Hopefully your new build with the new head gaskets and ARP bolts will fix things.

 

Have you used the TM program? I've enjoyed experimenting with it a great deal and have started a small library of saved combinations.
With regards to the intake tract length, for whatever reason, (and I've discussed this with the principles involved in the program development at Speed Talk), changing the length in the program doesn't affect the cam spec generated by the other various selectable inputs. It's odd in that way but it does give a perspective on how the change in length will be reflected in where the peak TQ and HP RPM values fall. Unfortunately (at least in my case and few others) there's no value for something like the RPM Air Gap or similar dual plane designs as the lengths aren't the same from port to port.

 

The timing issues exacerbated the head gasket flow problem it seems.

The Vortec heads appear to have survived.

However - I got it all back together with the AFR heads, etc and there was still an enormous amount of crankcase pressure. Tore it all back down and found 4 pistons with broken ring lands. The top rings lost their tension also. It did have correct ring gaps when assembled but likely the extreme combustion temps caused the end gaps to close up and broke 3 pistons on the driver's side, and 1 on the passenger side. Cylinder walls are fine as were the rod bearings, etc.

Forged pistons and scat rods are here and ready to go in today. I'll have it running again soon.

GD

 

Wow.
Good thing you were able to save what you did.
I fear I'm probably in the same boat as you as I went through an issue with my fan controller and experienced a few moments of overheating. And detonation too.
Good luck with the rebuild. Which SCAT rods did you get?

 

These are the rods I got:

https://www.summitracing.com/parts/sca-25700716

And since I'm in here and I'm doing forged pistons I'm dropping the CR to 8.5 so I can run some significant boost. My tuner wants to do a pair of GTX 3076 ver. 2's..... Maybe. LoL.

GD

 

Same connecting rod family as I was looking at although in a 6".
As for the pistons, at 8.5:1, there's got to be a dish. What shape? I've been looking at the Ross D-dish version. For the quench and all that (383 with 65 cc heads).

Turbos eh? Well, there goes the neighbourhood .

 

I'll get a picture of the pistons. They have a D shaped dish and valve cutouts. The only thing I could easily get without a custom order was a set from ICON due to my stock 4.000" bore.... They appear to be very nice pieces though. Very thick ring lands, really nice machine work and polished faces. 2618 forgings. Spirolox. This time since I'm building for boost I put all the ring gaps to about .030" or so.

GD

 

What ring pack do you figure? I like the looks of the 1.5mm/1.5mm/3.0mm ring package.

 

Dictated by the pistons. These are the typical 1/16, 1/16, 3/16.

I would rather some thinner units. But in the grand scheme of performance it's not going to matter all that much.

GD

 

Certainly not with a couple of turbos.
I'll be watching.

 

Here's the new piston:


This is a 18.6 cc dish.

GD

 

Still keeps a healthy quench pad despite the dish. That's what I'll be looking for should a 383 emerge from my pile of parts.

 

Outstanding! Now, I have a new New Years Resolution. Thumbs-up and keep up the good work.

 

Thanks.

I swapped to the AFR heads, dropped the compression quite a bit and well - here's my thoughts:

1. The dyno results with the AFR heads went down. It's right about 295 RWHP at the moment. This is due to the drop in compression, and I must also conclude that the Vortec heads, as they were setup (larger exhaust valves, and higher lift with PAC racing beehives) were NOT a significant restriction to the 350 with the FIRST manifold. As others have pointed out, the AFR heads probably need more like a 383+ to really show their strength. But I'm doing a power adder so.....

2. The Vortec heads did make 324 on the dyno. However they were very prone to detonation on the street at the ~9.8 compression I was running. Forcing me to dial back the timing several degrees on the street. So they were probably down 15 HP from that number in practice.

3. The 8.5 compression on the AFR heads runs AWESOME. It's extremely smooth and will take any timing you throw at it. Actually feels faster than the Vortec heads did though the dyno numbers are lower. I have thrown as much as 42 degrees at the engine and I can't make it detonate. It falls down the back of the curve. I even ran a tank of regular 87 octane in it at the same peak HP timing and it didn't care.

4. I'm now a Procharger dealer and we ordered our two-kit buy in with their Black Friday sale. I ordered with the 15-18 psi pulley so that should be interesting. With 8.5 I should be able to run a lot of boost.

GD

 

This just got a whole lot better.