383 DCR and quench questions - Lateral-g Forums

**WSSix** · #1 07-13-2016, 08:37 AM

No, you're most likely correct, Scott. I'm either overthinking it or just simply not fully understanding. I like to know why and how when I build things and that can lead to confusion.

I've never had a problem with the opti sparks on my LT1 engines though it is the weak link in the entire design. I'll probably add an MSD box and coil to the system though just to ensure I'm getting a good hot spark.

So you think I'd be fine using 93 octane with a tight quench and a DCR pushing 10:1? That's basically what I'd have with an SCR just under 12:1.

I've emailed Ai to see what they will say as well.

Thanks Scott

Che70velle · #2 07-13-2016, 09:35 PM

Quote:

Originally Posted by WSSix

No, you're most likely correct, Scott. I'm either overthinking it or just simply not fully understanding. I like to know why and how when I build things and that can lead to confusion.

I've never had a problem with the opti sparks on my LT1 engines though it is the weak link in the entire design. I'll probably add an MSD box and coil to the system though just to ensure I'm getting a good hot spark.

So you think I'd be fine using 93 octane with a tight quench and a DCR pushing 10:1? That's basically what I'd have with an SCR just under 12:1.

I've emailed Ai to see what they will say as well.

Thanks Scott

Trey, I think so. Keep in mind that the tighter the quench, the more efficient the chamber, the more compression you can run. Of course you have limits on how close you can get the piston to the head, and if you get the quench too close, you end up with piston to head contact. .030 is about as close as most builders dare to go, even with top tier crank and rod assemblies.
I'd go with it, and play with ignition timing as necessary. My plan "B" would be pulling up to the pump that sells E85...
Let us know what AI says. After all, they sold you the stuff.

**WSSix** · #3 07-14-2016, 08:12 PM

Ai got back to me today and their response was that there are more important factors than just DCR. Cylinder pressure for one is more important. Also, ensuring I have a clean air mixture, ie no oil ingestion, is a part of the equation. So I'm no too concerned with it any more. I'll trust these guys and what they're telling me. They've done this many times before. I'm going to shoot for an 11 to 11.5:1 compression ration. That's .5 to 1 higher than stock. I'm sure I'll be fine since I'm fully forged and we seem to have pretty good gas in this area.

I do wonder if I should go ahead and plan for a catch can on the PVC line. Historically, LT motors don't have the oil ingestion issue LS motors do. I guess I can always add it later if I end up needing one.

Also, anyone know of a quality forged piston I can run that has a 10 to 13cc dish? I'd like to keep my quench tight. Those DSS pistons I found on Summit I don't know anything about. Mahle, SRP, and Wiseco all only have a 5cc piston or a boosted application piston from what I can find.

Thanks everyone

woody80z28 · #4 03-03-2017, 09:07 PM

I may be late to the party, but...

Just make sure you get a d-dish piston to maintain quench. I put cheapo Keith Blacks in my truck 357 to get to 9.7 with good quench. For a 383 I'd think there have got to be lots of options.

I would put a catch can from the start, too. You know it's clean on a fresh build, why wait to see if it gets oily when you can just prevent it?

**WSSix** · #5 03-06-2017, 11:54 AM

Not a bad idea on the catch can, Woody. I may need to look into that addition.

I have the engine at the machine shop. I'm running Mahle +5cc valve relief pistons. Going to have the block decked so the piston is 0.013 to 0.015 inches in the hole. That will give me a quench right at 0.040 inches with the head gaskets. Engine won't be back until the end of April.

Thanks!