SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: bvparr on April 06, 2014, 11:33:57 PM
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I am needing help on tuning my engine I just had rebuilt and some changes where made to it. Anyway here is what I have and where I am currently at. I will be looking for advice on setting the base tuning to get me out on the water. To note I also want to tune it conservatively as I can not use all the power anyway. So here is what I have:
Chevy 468 LS6
8 to 1 D dished pistons
Engle TCS-7 HYD cam
Race Aero twin turbo system with intercooler using Rayjays
Single Holley blow thru 850 double pumper
MSD 6AL
MSD BTM 8762
Holley Red electric fuel pump - had a mechanical but last shop pulled it off. Worried that the Holley Red will not provide enough psi under boost and should get the mechanical back and put it on. Seemed to work fine before. Think it was just the mechanic's preference.
fuel regulator
I would like to note that this was a proven system for almost 20 years and ran great. The changes to the system are now the fuel pump and that it is in a 28ft Hawaiian jet boat. Came out of a 28ft Fountain with outdrive. The jet has a stage 2 and is rated for 600hp. This engine was close to 900hp.
I currently got it to run on the trailer and all seems okay. But I want to tune it now. So I have the advance at 3500 rpms at 32 degrees and at idle it is around 18 degrees. Gap on the plugs I believe is to wide at .050 and think I should narrow them to .025. When setting the idle it seems to like 1200 rpms and anything lower then 1100 starts to get a little jumpy. When turning in the 4 mixture screws doesn't change anything so I backed them each out 1 1/2 turns. This being the first time for me and not that knowledgeable but learning as I go.
My goal is now to just to be able to use the boat. I want to keep it conservative and will not be racing it. I am also not really sure what to set the BTM at. I will always just use pump 91 gas. So not sure if I have to turn the dial up to 3 or set it at 0 or what?
For tuning I would also like advice on steps of how to do it meaning what do I set first, the idle mixture and rpms or the carb or the idle timing? It seems okay and I was able to run it for a little bit on the trailer parked in the lake. Was a little rough pushing the throttle up to 3500 rpms as I did it slowly. Not sure if that is from too wide a gap on the spark plugs or the fuel pump, but I think it should be smoother then what it is. Also if I rev it quick and drop it back to idle it dies.
As I said before I am worried now about running to lean with this fuel pump and destroying my engine now. So I am afraid to take it out until I make corrections to what I have.
Thank you for any help on this. I am really close this time and am so excited to being finally able to use the boat.
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I am needing help on tuning my engine I just had rebuilt and some changes where made to it. Anyway here is what I have and where I am currently at. I will be looking for advice on setting the base tuning to get me out on the water. To note I also want to tune it conservatively as I can not use all the power anyway. So here is what I have:
Chevy 468 LS6
8 to 1 D dished pistons
Engle TCS-7 HYD cam
Race Aero twin turbo system with intercooler using Rayjays
Single Holley blow thru 850 double pumper
MSD 6AL
MSD BTM 8762
Holley Red electric fuel pump - had a mechanical but last shop pulled it off. Worried that the Holley Red will not provide enough psi under boost and should get the mechanical back and put it on. Seemed to work fine before. Think it was just the mechanic's preference.
fuel regulator
I would like to note that this was a proven system for almost 20 years and ran great. The changes to the system are now the fuel pump and that it is in a 28ft Hawaiian jet boat. Came out of a 28ft Fountain with outdrive. The jet has a stage 2 and is rated for 600hp. This engine was close to 900hp.
I currently got it to run on the trailer and all seems okay. But I want to tune it now. So I have the advance at 3500 rpms at 32 degrees and at idle it is around 18 degrees. Gap on the plugs I believe is to wide at .050 and think I should narrow them to .025. When setting the idle it seems to like 1200 rpms and anything lower then 1100 starts to get a little jumpy. When turning in the 4 mixture screws doesn't change anything so I backed them each out 1 1/2 turns. This being the first time for me and not that knowledgeable but learning as I go.
My goal is now to just to be able to use the boat. I want to keep it conservative and will not be racing it. I am also not really sure what to set the BTM at. I will always just use pump 91 gas. So not sure if I have to turn the dial up to 3 or set it at 0 or what?
For tuning I would also like advice on steps of how to do it meaning what do I set first, the idle mixture and rpms or the carb or the idle timing? It seems okay and I was able to run it for a little bit on the trailer parked in the lake. Was a little rough pushing the throttle up to 3500 rpms as I did it slowly. Not sure if that is from too wide a gap on the spark plugs or the fuel pump, but I think it should be smoother then what it is. Also if I rev it quick and drop it back to idle it dies.
As I said before I am worried now about running to lean with this fuel pump and destroying my engine now. So I am afraid to take it out until I make corrections to what I have.
Thank you for any help on this. I am really close this time and am so excited to being finally able to use the boat.
http://www.westechperformance.com
-beerjet-
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CORRECTION:
It is a draw thru system not a blow thru.
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I was lucky today to talk to World record winning Greg Shoemaker. So here is the changes I will be making:
32 advance timing is okay but better to lock out at 30. I will look into how to do that.
set plug gap at .030
take out fuel regulator no need with a Holley Red
Keep an eye on boost and do not push it up to hard on pump gas. Might need to look into a way to limit or regulate boost. Not sure what this system is capable of.
Set primaries on carb to 1 1/2 turns out and secondaries at 3/4 to 1 turn out.
Take it on on lake and run it under load and see how it does. So that is what I am going to do.
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Short of a dyno, Greg could give you a baseline.
You mentioned you wanted it tuned mild so you could just jump in it and go.
A dyno session could show you it's full potential, and then be detuned from there.
You take it home, drop it in, and go.
Greg is super sharp and a wealth of knowledge.
-beerjet-
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CORRECTION:
It is a draw thru system not a blow thru.
In your first post, you state that you are running a "Race Aero twin turbo system with intercooler using Rayjays" and you have now corrected that you have a draw thru system.
My first concern is that when running a draw-through turbo system; the carb is connected to the inlet side of the turbo, air and fuel is drawn into the turbo, finely the air and fuel is pushed into the engine. When running an intercooler on a draw-through, you have wet flow through the intercooler. That means that air AND fuel is being pushed through the intercooler, the intercooler being mounted between the turbo and the engine. When the air/fuel mixture is cooled, the fuel will condense in the bottom of the intercooler. A draw-through system really does not lend itself to intercooling.
In a blow-through system, the carb is installed between the engine and the turbo. Fuel is not introduced into the airstream until just before it enters the engine. Flow through the turbo and related ducting is dry, no fuel flowing through it. All manner of intercooling can be plumbed between the turbo and the carb. Finely, a cooler, denser charge of air can be forced through the carb. A blow-through system would also like a rising rate pressure regulator and enough fuel pump to overcome the increase in air pressure present in the float bowls, resisting fuel flow by pushing back against the fuel trying to flow into the bowls. With all of that being said, a Holley red pump, only puts out a flow capable of 7PSI (pressure is the result of resistance to flow). Once your boost level present in the bowls exceeds the output of the pump, fuel flow will reverse. Keep in mind that you also need to compensate for G-forces acting on the fuel in the lines on acceleration.
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32 advance timing is okay but better to lock out at 30. I will look into how to do that.
Take it on on lake and run it under load and see how it does. So that is what I am going to do.
I would strongly recommend locking out all advance in the distributor and controlling your advance curve and boost retard electronically. An upgrade to a digital programmable ignition might be in your near future. I have heard some amazing things about the new Holley Dominator EFI system. It is worth a look, especially if you are considering adding a data logging system. With a system like this, you would have the ability to change between tunes for pump gas and race fuel at the touch of button. You can eliminate all of your gauges. It also has built-in data logging capability. And it gives you the upgradeability to control EFI should you choose to go in that direction.
What distributor do you have? Some aftermarket distributors can be locked out by altering the orientation of the advance mechanism. Back in the day, we used to weld them before availability from the aftermarket.
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...take out fuel regulator no need with a Holley Red
Take it on on lake and run it under load and see how it does. So that is what I am going to do.
What mechanical pump were you running and why was it swapped out? Just because your old shop didn't like it?
Be advised that the Holley red pump is rated at 97GPH at 7PSI. In my opinion, a red pump is better suited for a street rod with a ZZ4 crate motor that will cruise from car show to car show, not a serious turbo application.
In an attempt to prevent a total nuclear melt-down, I would approach lake tuning, starting with some part-throttle runs and checking your plugs, after each run, for signs of detonation. If you choose to run the red pump, keep an eye on your fuel pressure. If you see a pressure drop as you accelerate, it is not up to the task.
What do your fuel lines consist of? Your suction side should be sufficient to provide enough flow to the pump without restriction. I would also recommend not running a filter between the pump and the tank at all or, if you feel the need to protect your pump, run a coarse mesh filter between the tank and pump. The pump will tolerate small debris flowing through it. Run a good filter that is capable of withstanding full system pressure (and flow), on the pressure side between the pump and carb. A filter on the suction side can cause pseudo cavitation in your fuel pump. I now filter every drop of fuel as it enters my tank with a filter funnel.
A final thought on electric pumps, I would mount it as low as possible and behind the tanks to promote gravity flow to the pump to prevent starvation. If your system utilizes a regulator, mount the regulator forward of the carb. Install low pressure lines from the regulator to the carb so that all low pressure fuel flow is from front to rear, with no changes in direction from rearward to forward. G-forces on acceleration will resist fuel flow and pressure at the needle and seat valves will drop.
Horsepower - if you aint feeding 'em, you aint got 'em
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Keep an eye on boost and do not push it up to hard on pump gas. Might need to look into a way to limit or regulate boost.
You will do this with your wastegates. How you control them will depend on what you have or what you choose to upgrade to.
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Thank you beerjet and Flusher. I would like to dyno but not wanting to pull out of boat after just installing it. Unless there is a way to do that while it is in the boat?
Flusher - I will look up the part numbers and components for the distributor and mechanical pump. I would feel more comfortable with the original pump that came with this system. It worked fine before. I hope I can install it back on now while the engine is now in the boat. And yes it was the mechanic's personal preference.
Also was wondering what type of boost this system was capable of. From the research it looks like can be around 18psi? So if running pump gas will that affect the boost and not allow it to run up as high vs. running race or av fuel? Also if running pump do I need to have the BTM on 0, 1 2 or 3? Still trying to learn this part. I know the higher the number the more it retards the timing. I was assuming that the the higher the grade fuel the more you need to retard? But maybe I have it backwards.
Thanks so far for all the advice. I have come this far and do not want to hurt it at this point. I will definitely make changes to it before taking it out. Oh and when I do take it out when you say read the plugs what color am I looking for and do I have to pull all the plugs or just one and what one is best to pull?
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Your boost will depend on what your wastegates open at. The lower the detonation resistance of the fuel, the less boost and timing you will be able to run. I may be missing it, but are you running aluminum or iron heads? With aluminum, you could get away with a pound more boost over iron because of heat loss conducted away from the combustion chamber.
Could you post up some pics? Anything would help at this point.
More to come later...
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Check out this post by icecreaman
http://www.socaljetboats.com/the-no-wake-zone/big-block-chevy-guys-what-is-your-timing-set-at/msg226505/#msg226505 (http://www.socaljetboats.com/the-no-wake-zone/big-block-chevy-guys-what-is-your-timing-set-at/msg226505/#msg226505)
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A few links to spark your imagination.
http://www.dragstuff.com/techarticles/reading-spark-plugs.html (http://www.dragstuff.com/techarticles/reading-spark-plugs.html)
http://www.dragstuff.com/techarticles/how-to-read-plugs.html (http://www.dragstuff.com/techarticles/how-to-read-plugs.html)
http://www.dragstuff.com/techarticles/plug-pictures.html (http://www.dragstuff.com/techarticles/plug-pictures.html)
http://www.strappe.com/plugs.html (http://www.strappe.com/plugs.html)