Detonation Problems

[Duke]

you can also buy sunoco 260 gtx its 98 octane unleaded and unoxygenated you can buy it on the net. thats all i run in mine, great fuel!

[xounlistedxox]

are you running the f.m.u that you should have with the supercharger? if not that's where your detonation is coming from under boost its reversing the fuel back to the tank instead of putting it to the fuel lines and injectors. plus you need more pressure than stock with bigger injectors.

Fhis setup didnt come with an fmu. I thought with 42lb injectors there should be more than enoigh fuel for my setup

[xounlistedxox]

Think running a smaller plug gap would help? Im at.038 right now with one step colder autolite 24s. Or maybe even go with autolite 23s?

[Oldfox]

When I first put the supercharger on my Mustang I couldn't go over 8LB
boost the pinging was so bad. I Added a MSD-BTM and It works great.

[xounlistedxox]

I called up CUNDN Racing to ask them some questions about my setup. Unfortunately all of their techs were gone for the day, but the woman that answered the phone asked me some questions. As it turns out I forgot to unplug the hose that goes from the valve cover to the throttle body and cap the ends. I already had a breather installed, but for some reason I wasn't taking into account that means that there was un metered air entering into the engine etc. I removed the hose and capped both ends. Turned the Timing back up to right about 8* advanced and no audible detonation so far. I'm going to drive it for a couple days and see how it goes.

[xounlistedxox]

Long overdue update.

I'm now running the motor I was building when I started this thread. Rebuilt stock forged piston bottom end from a 91 5.0, trick flow tw 170 heads, holley systemax 2 intake, 70mm throttle body, upr boostmaster pipe, bbk shorty headers, bbk catted x pipe, flowmaster delta 40's, f cam, 3.27 gears 2975lbs

I now have an msd 6 btm, and an aeromotive 1:1 rising rate fuel pressure regulator. Running MSD wires, and ngk plugs gapped @ .035 Have only on rare occassion heard detonation, but it's very infrequent.

With a nearly new engine complete with sensors and all it's running a lot better than it used to.

My SN 2000 has the upgraded impeller. 6" crank pulley 4" head unit pulley. I've seen about 7.5psi on my boost gauge

-Now I just need to find out how much timing I should be running for CA 91 octane on the street, and how much total timing on sunoco 100 octane at the track. My computer is an a9p, so it has more aggressive timing curves than an a9l.

ECU	1000 rpm	1800 rpm	2600 rpm	3500 rpm	5000+ rpm
A9L	8 °	18.5 °	22.5 °	22 °	26 °
A9P	21.25 °	21.25 °	27.25 °	26 °	30.75 °

Wideband will be coming soon, so I won't have to ask these questions anymore.

Thanks In Advance,
Brandon

[Duke]

I am running 14 degrees.

[xounlistedxox]

14* total advance, or 14* initial advance?

What type of fuel? What computer?

Thanks

[shopo27]

try closing your sparkplug gap. Can go down to .025. I run mine at .028 no detination or high rpm miss

[xounlistedxox]

Got my wideband installed today. I picked up a new lc-1 setup and installed it. I did some adjusting today to spark and fuel. I wound up running out of time while tuning, but as soon as my rpms hit 5k+ it goes lean into the low 13.x range. This is after turning the msd btm up to remove about 2.75* timing per lb of boost. My base timing is 8* btdc. As you can see by the graph above my A9P computer adds in a ton of timing, 30.75* advance @ 5k+ rpm. I also turned the base fuel pressure up to 55psi & am using an aeromotive 1:1 rising rate fuel pressure regulator & still runing out of fuel. I'm thinking I need to get an A9L computer to be able to properly adjust my setup since I would rather not run base timing of less than 8* btdc.

[xounlistedxox]

3-31-13 Installed an A9L computer yesterday. Turned BTM down to 1.5* timing retard per lb of boost. With the A9L installed my wideband instantly stayed in the 12.x:1 air/fuel ratio. Now I just need to get out there and dial it in more. It feels so much better than when I had the a9p & pulling 3* per lb of boost.

[xounlistedxox]

Update 4-3-13 Looks like the computer will modify injector pulse width to keep the air/fuel ratio @ target. Unfortunately the target for the a9l is 13.5 air/fuel. I'm now looking at picking up a Ford SVO Extender since it allows you to change your target air/fuel ratio @ WOT.

[xounlistedxox]

Update 4-8-13. Picked up an old school ford svo extender. Installed it this morning. Results thus far look promising. When I hit 3rd gear it was at a steady 11.1:1 air/fuel ratio. I need to get out to the track now to get it dialed in and see what this setup can do.

[xounlistedxox]

Well after more driving I noticed my afr's were erratic at best. Sometimes it'd hit 10.8, other times it couldn't even get in the 12.x range.

So, I ordered an Aeromotive 340lph in tank pump to replace my walbro 255. The walbro has less than 10k miles on it, so I was reluctant to replace it so early.

Put the Aeromotive 340lph pump in today. Went out for a test drive after setting the fuel pressure to the mid 40psi range(the needle on my gauge jumps, so it's hard to tell where it's at exactly. First test drive when I went WOT it actually started breaking up, so I looked at my wideband and it was down to 9.x:1 afr's. Apparently the 340lph was the answer. I dialed the extender leaner and it seems to be able to stay locked in in the low 11.x range.

Time will tell I guess.