Too much boost???

  • Thread starter Thread starter sweetgn
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Just curious. I have run 12.96 before on 1 stage alcohol injection( 70% isopropyl) with about 16 lbs of boost. Lately after putting in two stage alcohol injection and a 'seventh injector' and running 24lbs of boost with no knock retard and O2's at 780, WHY am I running 13.6 at the approximate same temperature. I don't understand. Could the extra alcohol and fuel be just too much to put in the intake pipe? I have a .020" jet in the fuel and a combined jetting of .046" for the alcohol. I wouldn't think this would hurt with 24 lbs of boost. Could I be just on the border of bogging and not know it? I know some of it is the driver:), but I would think 24 lbs of boost would make a slight improvement since I was able to run high 12's before. By the way I have blue tops with the fuel pressure set at 46lbs with vacuum off.

Thanks for any help!!
I think you answered your own question. With alchy injection, there is an initial cooling as the spray first hits, and the cylinder temps begin to raise as the run continues. The second shot of spray (in your case) is not allowing the cylinder head temps to raise. That is part of it.

Secondly, the charge has so much water in it, that it burns so slow, that a lot of the fuel is going, un-burnt, out the exhaust.

You may want to try running De-natured now, as the cooling effect is not as great.

Of course (as you know) the alchy jet sizes could be lowered as well.

The seventh injector might be turned off when using straight alchjy, as this is a fuel as well, though not as 'energy dense'. Of course with 24 psi, you may want the extra fuel. A richer mixture helps to cool as well.

You have a lot more options than the rest of us. This should be a killer combination, once it gets dialed in!

Do you have a scan tool? How about an egt. sensor? Egt's numbers are relative to each combination. What is good for you, may not be right for anothers set up. Still this is a great tuning tool....

I'm envious of all the options you have, though I'm not sure that I would like things to be so complicated! :)
I guess I have to do a lot of 'tweaking' to get it right. I hope it works, I spent a good bit of money and a LOT of time designing and installing this setup. I will try lowering the jetting of the second stage first and go from there. I appreciate your response, as it backs up what I figured might be the problem.
I do have turbo link, but I don't have an EGT.
I just thought of something, since running high twelves, I have had a third muffler installed. I bet that didn't help any. But I think I still have some tuning to do as I just read a thread about someone running 10.97 with alchy injection and 3 mufflers. My setup has a 3" cat(still operable), 2 Edelbrock center to centers, feeding a stock replacement Walker 2in2out stock location muffler.
I got sick of the drone and all my neighbors telling me they can hear me coasting two blocks away.
BTW, Turbo Tim, I see you have a 62MM throttle body. Did you notice a big improvement with that?
I put the 62 on with a hemco plenum. Result was 2 lbs less boost. (less restriction) I bought the 62 because it was a highly polished piece, and got a decent price on it. I was able to get 2 more psi without knocking. The hemco worked. The 62 is still pretty.:)

I would put the new spacer from RJC products on now. Same effect as the Hemco, a LOT less money! Dyno tests showed 25 foot pounds more torque, as well as an immediate gain of 2 tenths. That's bang for the buck!...

BTW, the muffs you put on, how large in diameter are they? I have a 2 in 2 out muff in the stock location, and will be putting a pair in front of the wheels. I want the smallest profile I can get. How well does this work? Are we talking whisper quiet at cruise?

Saw a SMC EGT set-up somewhere for $140. That's reasonable..
I believe the Edelbrock center to center's are 2 1/2" in diameter. I'm not sure as I didn't buy them, they were on the car when I
bought it. I wouldn't say it's whisper quiet, but at least to my ears the drone is very liveable. I'm sure if you ask around someone will have a whisper quiet system. I really don't think the
center to center's will give you a big drop in sound. You will probably have to go with an offset muffler. I just went with it
because they were already on the car and were not even close to being worn out.
My first question is: Do you still have a stock turbo on your T? Looking at your sig, I think you do.

If you do have the stock turbo then you are probably beating the air to a higher temp to get more pressure. Try backing off the boost and see if performance increases, if so you will need a larger turbo to do what you are trying to do.
It is a TE-60. I have reduced the size of my second stage alcohol nozzle to see if that helps.
Thanks for responding.