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I apologize to everyone for being grumpy and probably coming off as a testy or salty bastard yesterday. Having to find alternative heads due to my blunder got me in a foul mood.
On the plus side the spare LS3 intake acquired as a surprise for my intake test thread may be useful to this build instead sitting on the coffee table in the living room as "a redneck work of modern artwork" to annoy the girlfriend. Maybe I should move the car parts before I end up sleeping in the TA instead of rebuilding the car...wink...morning humor.
Sxc z28 & Post64 - I will talk with Jeremy @ RPM about the RST vs RXT - thank you for the heads up.
Blk02SS - agreed 100% on head comments at heart, but Mast Web page says the medium bore LS7's are sold out.
AR Shale Targa - thank you for the tip on the Mamo top end. With the 62 cc chambers they will have too much compression for my short block unless the car is on race gas or E85.
Looks like I need a cylinder head with about 74 cc chamber. The milled ~ 61-62 cc GMPP's ended up at like 13.5 to 1
We could open the chambers up some and maybe get to 12.5 to 1
Summit compression calculator yielded these results
What the limit on compression for 93 Octane gas for a full weight TA?
My 72 Vette runs 10.85 to 1 compression with a carb on 93 just fine. Iron Dart 400 Aluminum Dart Pro 1 heads & intske. Cam is spec'd accordingly. My LS RS runs 11.3 to 1 no issues. i see other run LS motors ~ 11.5 to 11.8
I think the bigger 4.070 bore and domed pistons are more prone to detonation than a 3.9 bore with flat tops at the same given compression.
317's might work...
Last edited by 99 Black Bird T/A; Apr 14, 2017 at 06:28 AM.
Threads are starting to blend together, so I apologize if this is a repost. If I were building your engine for my car, I would use the mamo 250 heads if we are talking cathedral.
If I was going rectangle, I would use the mast 260cc runner rectangle port heads. They are smaller than the LS3 stock runners AND outflow them. Explosive power. I would still send them to mamo to be hand worked over, since he just knows how to extract flow so well.
I know it's money, and I know it's expensive. I'm just the type of person who isn't satisfied if I know I left something on the table. Anyway, whatever you decide to do Im sure the motor will be phenomenal!
Looks like I need a cylinder head with about 74 cc chamber. The milled ~ 61-62 cc GMPP's ended up at like 13.5 to 1
We could open the chambers up some and maybe get to 12.5 to 1
Summit compression calculator yielded these results
What the limit on compression for 93 Octane gas for a full weight TA?
My 72 Vette runs 10.85 to 1 compression with a carb on 93 just fine. Iron Dart 400 Aluminum Dart Pro 1 heads & intske. Cam is spec'd accordingly. My LS RS runs 11.3 to 1 no issues. i see other run LS motors ~ 11.5 to 11.8
I think the bigger 4.070 bore and domed pistons are more prone to detonation than a 3.9 bore with flat tops at the same given compression.
317's might work...
You might want to double check your numbers. If I'm not mistaken, ERL uses Wiseco pistons and they don't make a 3cc domed piston for a 416. They do make a piston with a 3cc valve relief, which is expressed as -3cc in their catalog.
I might look at the SPS Haymaker LS3 heads. 264cc runner but a 2.125" valve... and flow 375cfm. They avg a C/D of 105 which is on par with TFS 245s. Which are the highest Coefficient of Discharge heads out there right now.
The formula for coefficient of discharge is as follows: C/D=airflow/curtain area. Curtain area=valve diameter x Pi x Lift.
A comparison of heads I put together this morning:
You might want to double check your numbers. If I'm not mistaken, ERL uses Wiseco pistons and they don't make a 3cc domed piston for a 416. They do make a piston with a 3cc valve relief, which is expressed as -3cc in their catalog.
Thank you I will check. The screen shot of the compression calculator was provided by the cylinder head shop.
The screen shot of the short block build sheet is on another device and I'm out of town. I will post the build sheet Monday. ERL is A+ with documentaction!
Here's the basic info.
I think based on memory, this is the piston used.
Wiseco K464X7 Chevy LS Series -3cc Dome 4.070 inch Bore Piston on a few sites
Summit lists it as a +3 dome.
So there may be some confusion about this "dome" when meaning -3cc or +3cc
Thank you again for pointing me at Wiseco's page.
Jake, thanks for the Haymarket info...sweet!
Everyone, thank you for head suggestions and I'm looking and reading.
Last edited by 99 Black Bird T/A; Apr 15, 2017 at 07:54 AM.
This 4.070 piston has a 3cc dome. The 3cc are the extra material above and beyond the valve relief volume, that's how I would explain it. The manufacture calls it dome volume, it can be confusing when using the on line calculators and the -/+ selection.
Use -3cc for calculation. The valve reliefs displace more volume than the dome on those pistons.
I think Wiseco calls them a reverse dome since they actually end up removing material from them. Even some of the blower dish pistons are reverse dome since they add material about the piston to help with quench and flame travel but have more material removed to create the "dish."
A) 74cc chamber -3cc = 71cc chamber that is smaller chamber and more compression or
B) 74cc chamber reduce compression by -3cc as in
74cc - -3cc = 77cc compression and an overall reduction in compression
If you look at the Wiseco catalog, you will see on page 15 that the 5cc piston results in a higher compression ratio than the -3cc, then the -8cc piston results in even lower compression. That should confirm that the negative values should be calculated as dish volumes and the positive values like dome volumes.
If you look at the Wiseco catalog, you will see on page 15 that the 5cc piston results in a higher compression ratio than the -3cc, then the -8cc piston results in even lower compression. That should confirm that the negative values should be calculated as dish volumes and the positive values like dome volumes.
Yes, I read that and I appreciate the detailed explanation.
I need to be absolutely sure I have the correct understanding before talking to the person reworking the heads and discuss this dome is a defacto dish.
Yes but, the compression calculators on line say to use ( -) to input how much dome is used and a positive + or just the amount without + to input the dish volume on the crown of the piston and that's what's confusing to many. This one does not give that instruction but will not be accurate without adding (-) to piston head volume to describe dome. Got that? https://www.uempistons.com/index.php...tors&type=comp
You should call Wiseco''s tech and have them explain your part number, then there's no confusion. It does look like it has some extra material on top but just enough to keep the relief volume at 3cc instead of 4.5 or 5cc like some.
You should call Wiseco''s tech and have them explain your part number, then there's no confusion. It does look like it has some extra material on top but just enough to keep the relief volume at 3cc instead of 4.5 or 5cc like some.
THIS ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
that tiny little bump does not contain enough material to fill in the 6cc valve reliefs
I called Wiseco today. That was an excellent suggestion. Thank you 64Post.
It appears my cathedral heads will be borderline for 93 octane with high compression at ~11.8
The head porter is researching in detail.
It appears the quench will get jacked up or other compromises occur with opening the chambers enough to drop the compression .
This engine part of the build is dead in the water until a final review by Land Speed
LPE LS2 403 short block with pistons matched to these heads would have been smarter choice for this build and less frustrating in hindsight.
This ERL 416 may end up as Black Mamba solid roller LLSR cam engine.
These are the first solid rollers I've seen that I think might last 100,000 miles on the street. Not having to buy a fast intake has me thinking about that.
Last edited by 99 Black Bird T/A; Apr 18, 2017 at 04:11 PM.
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