350 EFI TBI Mods, cam, heads, intake, tune, 383?
08-02-2018, 08:49 AM
#81
Registered
Thread Starter
You have to look back at history on this one. The MEFI 1 came out circa 1993ish, and the marine industry was way behind in applying technology into boat motors. Processing power was limited as well. While its true you could give the spark table more resolution, but for what? Coming from a distributor with either weights, springs or vacuum the spark table on a MEFI 1 was much more capable considering the times. It offered a true 3D table. In addition most people simply didn't mess with the timing above 3000-3500 anyhow as you usually don't get any measurable performance gains.
The bigger problem is lack of available documentation on all the parameters and what they actually do IF even implemented. Hence F1 in this situation is confusing at the outset.
If you had a table that had spark break out points in 50 rpm increments and every 1 kPa that would be a PITA to monkey with. With MEFI 3 and up you have multiple tables covering a broader rpm and kPa breakouts AND they must match on the overlap points. Gets a little laborious when first playing around with it. In addition much of the table is never even used, nor is the motor capable of operating in that range. In the end some of the added fidelity is non-value added, or simply stated, useless. For example does a motor even operate at 10Kpa and 200 rpm? Nope.
Keep us posted. The work you are doing is fun to watch and we all learn something in the end.
The bigger problem is lack of available documentation on all the parameters and what they actually do IF even implemented. Hence F1 in this situation is confusing at the outset.
If you had a table that had spark break out points in 50 rpm increments and every 1 kPa that would be a PITA to monkey with. With MEFI 3 and up you have multiple tables covering a broader rpm and kPa breakouts AND they must match on the overlap points. Gets a little laborious when first playing around with it. In addition much of the table is never even used, nor is the motor capable of operating in that range. In the end some of the added fidelity is non-value added, or simply stated, useless. For example does a motor even operate at 10Kpa and 200 rpm? Nope.
Keep us posted. The work you are doing is fun to watch and we all learn something in the end.
You can see the resolution of the tables compared to the MEFI. So, GM had the ability to do it, but the weird thing is they used something close to FLASH technology on the MEFI and still used chips in the cars and trucks. Either way, after having converted the SBC in my truck to run on the 24X, coil per cylinder, sequential injection, 411 LS1 computer, I am half tempted to do it to the boat this winter too! But, the automotive industry usually gets the best technology first, which is usually driven by a push from the EPA for better emissions. If it weren't for that we would all probably still have carbs....LOL.
The TBI computer I am talking about is the 16197427 and the 16196395.
This is a picture of the last tune on my truck before switching the the 411 PCM. Its a 16197427 running $0E code I modified for a 2 BAR MAP sensor to read boost, 4L80E transmission.
If anyone is interested in a 24X conversion on your SBC or BBC, these guys are where you need to go.
https://www.eficonnection.com
Engine in my Blazer
Anyway, Heading to the lake this afternoon for the weekend. We will see how it goes! Will keep you guys updated. Glad to a make a thread that seems to have a lot of interest.
08-02-2018, 09:00 AM
#82
Registered
Thread Starter
Headed to Lake Barkley. We are blessed to have so many beautiful lakes in the great state of Kentucky!
https://parks.ky.gov/parks/resortparks/lake-barkley/
https://www.landbetweenthelakes.us/
https://parks.ky.gov/parks/resortparks/lake-barkley/
https://www.landbetweenthelakes.us/
08-10-2018, 12:21 PM
#83
Registered
Thread Starter
Well guys, I am going to have to admit defeat on this one.
The engine just will not stop spark knocking. I think like SB said, the cam is too small, especially with the amount of compression I have.
So I really do not want to change the pistons out, so it looks like I am going to be doing a cam swap.
I have tried everything, the only way I can even remotely get it to somewhat not knock, is to take a bunch of timing out of it, and run it really rich.
This is the cam I am looking at, its a GM Performance parts camshaft. Its the same cam that came in the old zz383 crate engine. Its actually a Crane Cam.
My dynamic compression is around 9.0:1, with the cam I have.
This cam will drop it a full point, and from my research works in a boat.
https://www.summitracing.com/parts/nal-19210723
The engine just will not stop spark knocking. I think like SB said, the cam is too small, especially with the amount of compression I have.
So I really do not want to change the pistons out, so it looks like I am going to be doing a cam swap.
I have tried everything, the only way I can even remotely get it to somewhat not knock, is to take a bunch of timing out of it, and run it really rich.
This is the cam I am looking at, its a GM Performance parts camshaft. Its the same cam that came in the old zz383 crate engine. Its actually a Crane Cam.
My dynamic compression is around 9.0:1, with the cam I have.
This cam will drop it a full point, and from my research works in a boat.
https://www.summitracing.com/parts/nal-19210723
08-10-2018, 12:45 PM
#84
Registered
You change compression to change compression.
You do not change the camshaft to change compression.
More compression let's you run more camshaft.
I wish this dumb DCR('dynamic compression ratio') thing never got traction or invented 12-15yrs ago. Only seems to get used when the compression of the motor is incorrect for the application.
==================================
Yes, that Crane Cam was used in many boats,especially with 9;1-9.5:1 383's. I'd say more Comp Cams 224/230 112 HR's...but that may be more due to cost ?
You do not change the camshaft to change compression.
More compression let's you run more camshaft.
I wish this dumb DCR('dynamic compression ratio') thing never got traction or invented 12-15yrs ago. Only seems to get used when the compression of the motor is incorrect for the application.
==================================
Yes, that Crane Cam was used in many boats,especially with 9;1-9.5:1 383's. I'd say more Comp Cams 224/230 112 HR's...but that may be more due to cost ?
08-10-2018, 01:49 PM
#85
Registered
Thread Starter
You change compression to change compression.
You do not change the camshaft to change compression.
More compression let's you run more camshaft.
I wish this dumb DCR('dynamic compression ratio') thing never got traction or invented 12-15yrs ago. Only seems to get used when the compression of the motor is incorrect for the application.
==================================
Yes, that Crane Cam was used in many boats,especially with 9;1-9.5:1 383's. I'd say more Comp Cams 224/230 112 HR's...but that may be more due to cost ?
You do not change the camshaft to change compression.
More compression let's you run more camshaft.
I wish this dumb DCR('dynamic compression ratio') thing never got traction or invented 12-15yrs ago. Only seems to get used when the compression of the motor is incorrect for the application.
==================================
Yes, that Crane Cam was used in many boats,especially with 9;1-9.5:1 383's. I'd say more Comp Cams 224/230 112 HR's...but that may be more due to cost ?
Crane part number 109831 https://www.summitracing.com/parts/crn-109831
"Good mid range torque and HP, fair idle, moderate performance usage, crate motor upgrade, mild bracket racing, auto trans w/2500+ converter, marine applications: for 350+ cu.in. modified engines with free-flowing above water exhaust systems for performance applications in light pleasure and ski boats, including jet boats, 3000-3800 cruise RPM, 9.5 to 11.0 compression ratio advised. Good w/supercharger, 10 lbs. maximum boost w/8.0 maximum compression ratio advised."
All the Comp Cams are advanced 4 degrees, which also contributes to more cranking compression. If it were not such a pain to do, I would retard the cam in the boat now 4 degrees, which should help, but if I am going that far, I might as well change the cam.
I know what you are saying. I built an LS2 402 stroker with almost 12:1 compreson, but the cam was a 242/250 @.050 113 LSA custom cam, and ran on pump gas with no knock at all and made 600 HP. I thought I could get away with a smaller cam in the boat 383 on 93 octane but was wrong. So, at this point I am swapping the cam.
08-10-2018, 02:16 PM
#86
Registered
LS motors can take another point or two of compression vs the traditional 23* sbc. Hard to compare the two motors with each other.
+ Boats under more of a load, and all the time vs notmuch, +slower accelerating speeds, than cars.
+ Boats under more of a load, and all the time vs notmuch, +slower accelerating speeds, than cars.
08-11-2018, 06:54 AM
#89
Registered
Thread Starter
It gets pretty nasty, still around 5000 RPM and on acceleration. Once it starts the computer just keeps pulling out timing, then I have to back off the throttle to let the timing come back. 
08-11-2018, 11:00 AM
#90
Registered
I know nothing about engine tuning but watched a friend tune a modified Merc 700SCI which are over 800HP now. Stock compression running 87octane and max timing in upper RPM is about 24* total advance. It's running a Holley EFI system.
