Hi Dave,
You're right. 180* seems to be the magic number as far as the blown alcohol guys are concerned. The other thing is they are pumping in so much alcohol that if the inlet temp drops too low it
takes a super hot spark to light it off. That's why they are ditching those killer MSD boxes for magnetos. Hang out on some of the hardcore racing boards if you want to learn from the pros
about running with alcohol.
If you notice on the brochures they give you when you buy race gas, they also specify a vaporization rate and it varies by brand. All everybody ever looks at is octane, but if you were real smart(I'm not) and knew what vaporization rate you needed for your combination, there is probably some power to be had when running race gas as well. I think this is also one of the reasons they tell you not to run AV gas in automotive applications as the vaporization rate is different than race gas.
SInce you seem interested, I'll tell you how I got to this point. I'm somewhat of a newbie to the Buick scene as I am just starting to sort out my GN.
I have messed with NOS and turbos for about 10 years. This is the 3rd car I've used it on. Let me tell you how it goes(listen up
Razor).
You tell yourself you'll just use a little to get the boost in faster and to make a little more power. It works, so you try some more, things break, but you fix them and use a little more, before long you have modified the car so it is totally dependent on the NOS and it can't get out of it's own way without the bottle. Maybe it's just me.
My current project is '69 GTO street car with a Pontiac(not a chevy) 350 that I put a Turbonetics 60-1 on sucking through a Holley 780. I know, old school carbureted, No EFI, no knock detectors, no intercooler, but it was sufficient to take the car from a 14.6 @96 to 12.6 @110 and still be streetable. I left out a lot of details, but enter the NOS.
I graduated from 1 to 2 to 3 foggers and even tried for 4, all dumping into the inlet side of the compressor, all staged seperately using Hobbs switches reading boost. I ended up running race gas from a seperate tank for the NOS as I could not control the knocking any other way. I also went up to a .96 exhaust housing on the turbo.
I experienced some major driveline failures(broken driveshaft yoke, numerous transmission failures, teeth ripped off the ring gear,etc) once I had that sorted out the head gasket failures started. I tried every gasket there was and finally fixed it by Oringing the head and using old fashioned Pontiac steel shim sandwich type gaskets with ARP studs.
Then I became obsessed with using the NOS in first gear. Up until then I could only use it in 2nd gear. I switched from Hoosier Quik Times to Quik Time Pros, went with 90/10 50/50 shocks, dropped down to 2.73 gears (hard to find for a 12bolt) switched to a very tight 11" convertor. By adjusting the turn on point of the individual foggers I got the launch sorted out.
I was only running 18-19 lbs boost, and 20* advance, but the big problem I had was the car would go bananas when I first hit it, pull like crazy, then after a few seconds the knocking would start. Not all the time, but enough that I had to address it.
Since I had no ECM to help me, I installed 2 MSD retard boxes triggered by switches on the console so I could reach down a few
seconds into the run and and take out some timing. I wanted to automate the process, but all the automatic retard boxes I looked at required an elaborate staging process to set them up each time you wanted to use them. I wanted to just punch the car anytime I wanted without setting all that up. I also added a 3rd switch to take out some boost.
This brings me up to last summer when I added alky to my Buick. Thanks to this board and the people who frequent it I was able to cut down my usual trial and error learning curve and get it pretty well sorted out in a few months. I'm currently using Razor's controller with SMC's external pump as I found the Shurflow to be too slow to react and I got sporadic knocking from a rolling punch. A Turbotweak chip has helped a lot also.
Using Direct Scan and moving my IAT sensor into the plenum on the Buick, I noticed that with a front mount intercooler and a single M15 alky nozzle running at 90psi, at 26psi turbo boost I was getting inlet temps on the Buick in the 78-88* range. So NOS may not be a good idea on my Buick, but you never know until you try.
Actually, my Buick is way slower than it should be for the stuff I've done to it, so it has occured to me that there may be something going on with the inlet temp here, but I haven't figured anything out yet.
Back to the GTO. I already had gotten an EGT meter from SMC for tuning the Buick, so I got an intake probe from Steve as well and measured the temp coming out of the turbo on the GTO and to my amazement it was around 300*. I always figured that dumping in 150HP worth of NOS ahead of the turbo would cool things down a lot, but that was not the case. Apparently the cooling effect of the NOS was being totally absorbed by the turbo.
I still got the extra oxygen which made the HP, but I never got the cooling to combat the detonation. As an experiment, I leaned out the secondaries of the Holley super lean and put an M15 spraying at 90 psi right after the turbo on my GTO and the charge temp dropped from 300-200*, just from adding that much alcohol. I couldn't get the Holley lean enough to dial in the mixture and I had learned what I wanted so I put the car away until I could set up the alky system properly.
SMC is making me a custom 1 gallon tank with return regulator capabilities and I'm going to use a Shurflow with a Mallory alcohol bypass regulator to dial in the pressure. Then I'm going to move
the foggers one at a time from the inlet to the outlet side of the turbo and switch them to Alky instead of the Race Gas. Taking a page from those alky racer's book, I am planning to put a temp sender in the tube leading to the intake manifold so I can mount a permanent gauge for monitoring the intake temp. I will probably leave at least one fogger on the inlet side just to keep the volume of alky injected reasonable.
If you like, send me your email address and I'll keep in touch and let you know how it goes.
Pete
turbogto@yahoo.com
