fuel pressure vs. alky

[BlackBeauty]

Hey folks, I'm trying to tune my alky kit all over again, since I got a PowerPlate for Christmas. It is trickier than I hoped.
I'm wondering if any of you lower fuel pressure when using alcohol injection. Say you're running 19psi without alky, at 47psi fp line off. If that's tuned for little to no knock, then it's time to turn up the boost with alky. Now if you plan on spraying alcohol, then that's 47psi of base fp, plus alcohol when it comes on. Would you instead lower the fp a couple psi so the alcohol doesn't make things too rich?
I wanna hear some tuning experiences about this.

 

[blackbuick87]

An EGT meter is very helpful in this situation

47 is pretty high to begin with. You can start out there, with maybe a little less alcohol, and watch your O2's but you are really just guessing.

There is no easy answer since every chip is different. List your chip, turbo, nozzle size, etc

By adding the power plate you should be able to lower you FP somewhat, but it is safest to start high and come down from there.

I usually run 43-44psi, Thrasher 100, power plate and a .030 jet for example. I get a little knock on the big end, so I am going to try a bigger jet vs. more FP.

I would rather cool the charge with alcohol instead of fuel, it does a much better job

 

[BlackBeauty]

Yeah, maybe I should've listed my mods, but I was just trying to get a bunch of general opinions on this topic. I have a TE-44, bluetops, Thrasher 92 (and an RA93), SMC unit, so whatever nozzle that includes.
I cannot get a good tune with either chip anymore. It seems like I blast it, and everything is fine. Then next time I floor it, I get way different numbers on the ScanMaster. I'm thinkin' about taking it to a local place that works on TR's and see if they can help me tune it on the dyno.

 

[Turbo__Tim]

BlackBeauty, assuming that you are in a good state of tune you should go to 42.5. That's actually a pretty good number.

Try pure de-natured, at half pump speed. Activate as late as possible. (1-2 psi before knock).

If you are trying to compensate higher fuel pressure due to running a stock pump, you need a good fuel pump.

You need to tell us what you are running, and what you have tried. We don't even know what psi you are getting knock at.

Spill it Dude!!

 

[BlackBeauty]

Are you saying I should go with 42.5psi fp line off? That sounds low, I remember on the Thrasher web site it says their chips are not designed to work with less than 45psi, which is why I haven't turned it down so low. I also have a hot-wired Walbro 307 fp. Sorry, I recently (accidentally) erased my mods list I had typed out, so I always remember a couple things at a time. Of course I have an adj. fpr too. I have never gone below 45psi.
With the Thrasher, I was able to get 19.5psi boost without knock (and with the alky kit turned off). Then I turned up the boost for the planned highway driving a couple weekends ago, so I could tune it for the SMC kit. I was able to turn up the boost a little, then turn on the alky barely, and be good. Then I turned up the boost a little more, and couldn't prevent knock no matter what (I didn't mess with fp, just the alky kit). This was at only 23psi or so. I was ok with 23psi and alky before the powerplate, but not anymore. So I turned it back down to 19psi, and now there is knock without alky. I did not change anything except for boost. Here in Orlando, days range from hot to cold in late Dec. and January. I think that may be screwing me, colder air is worse for me, it brings about knock I think. Does this help any?
One more thing, I read in a different post that an LT1 MAF sensor is sensitive to it's position... I have a stock MAF, and it's turned sideways to not interfere with anything else... does this make a difference? If that doesn't make sense, just imagine looking under your hood, and on the side of the MAF there are some wires sticking out the side. Well I rotated my MAF so the wires are now on the bottom.

 

[Turbo__Tim]

Ok Yes all that helps...

I have my MAF the same way, if that turns out to be true, let me know...

The cold air is denser, and will make your engine act as though you just turned the boost up. You are getting more oxygen, and leaning out.

OK It's getting late so I may have to re-visit this but here is something to consider.

A while ago a fellow here reported running 10.9 in the quarter, with approx 20 pounds boost. On pump gas, and alchy. Naturally he is an expert tuner, and runs a fairly large turbo (forgot what), and ported alum. heads.

So you can see the amount of power is not always measured by the boost guage. (I have ran 24# boost, and drowned the spark with too much alchy, and had a leaky turbo seal, and burned fins on the exhaust and ran 13.1 on pump gas, and alum heads. So boost lies...

The addition of the power plate is a proven performance adder. By equaling flow you are effectively addind the equivelint of 1-2 pounds of boost so power generated at 20psi with the plate could be equal to 22 psi without it.

As far as the thrasher, I don't have any experience with them. It could be that they reccomend you go with the higher pressure to keep you out of trouble. Leaner might be meaner in your case and the best way to find out is to drop fp gradually at the track and let the clock tell you which is better.

I would get the best times with the thrasher working with the best fuel pressure, without alchy first. Then add boost and alchy until you get knock.

With your set-up, the turbo you are running, the cool weather, pump gas, if you can manage 22 psi you should be happy. I believe you will hit a wall at about there anyway, unless you go 2 stage with the alchy, or run propane inj. which will allow 24 psi.

Keep in mind that running rich can bring on the knock, as can running lean, or drowning the spark with too much alchy. I drowned spark until I went 2-stage with the alchy.

One last thought. If after trying all this, look to Jay Carter for a chip meant to burn alchy. The thrasher is a great chip for what it was intended for, and the thrasher for the stock chips really rock, but I'll bet you would be much better off with a chip burned to chew up the alchy. Jay has done this for many years, and I liked the chip he sent me.

Good luck, and get an egt meter from SMC. You will avoid all that knock slowly pounding the crap out of the engine, and by keeping an eye on the temps will allow you to back off before knock happens.

Good luck, and take it one step at a time...

 

[blackbuick87]

What is your turn on point and pump speed?

Sounds like you will have to do like Tim suggests and start all over. I would recommend having a chip burned for your combo also. Thrashers work great, but the farther from stock you get the less effective they become IMO.

How much KR are you getting?

Another possibility is you could set you turn on point pretty high, say 15psi, and get a bigger jet for the alcohol. This should allow you to turn down your FP to 45psi