ChevyNo1

Thanks for all the info Steve!!! I really appreciate it.

Well, if I assume 15% drivetrain loss ( and I'm going through a 9" ), then I would be at 675, so close enuff!

How would the BSCF change if I was running 11.5.1 A/F, which I was?

Also . . . SMC recommends 100% alky, as does a local f-body guy . . . I don't know which should work the best! You're telling me one thing, I'm getting different answers all over the place. I suppose I could just try both

- Dug

ChevyNo1

Hey Steve . . . just got an email from SMC, he's gonna send me a #15 ( which IS 15gph @ 100psi ). I don't think his system actually builds that much pressure, I'll have to check. Assuming it only builds 50psi, I would assume then a #15 would actually be 7.5gph??

- Dug

Noyzee

iTrader: (37)

My buddy runs a 70/30 mix 0.99 for 2 1 quart botles. he was able to up boost about 2 psi with a #10 and low low speed, and high rpm. he didnt want to tune of just his scanmaster so next week we are dyno with a/f and scanmaster to see what it will do.
I almost wish i kept it now.

S_J_H

Dug, the 15GPH nozzle flows 15 at 100psi and 9.5 at 40psi.
Your a-f of 11.5 also includes your alcohol volume of 5GPH.

Straight alky injection and water injection are two COMPLETELY different things.

There is no comparison, if detonation control is what you are after then water is the key, not alcohol.
Alcohol is a great charge cooler and great way to add fuel if you have maxed out injectors. But alcohol is a fuel, water is not.


Here is a great old NACA paper on water injection as it was being tested for military air craft use-
http://naca.larc.nasa.gov/reports/1943/naca-report-756/

Shows what is possible with water. Pretty interesting stuff !
Also showed even at 1.5 times as much water to fuel , air mass flow did not decrease.This means water did not displace the air and most all of it is vaporized in the cylinder unless air temps are very high.
It does also point out, that water vs a fuel that is comparable in detonation control, will slightly hurt power.
They ran mixes as high as 1.5 times the volume of fuel.
That would be around a 84GPH nozzle of pure water on your car,lol.
Shows how tolerant an engine is of water!

I tried straight alky FYI. It did not control knock as well and coolant temps rose much higher after a run than with 50/50.
Also as weather changed, my A-F would vary greatly unless I rejetted the system to compensate.

But experiment a bit and see what works.

ChevyNo1

WOW, you are a LIBRARY of info on this, I can't thank you enough!!

Hmmm . . . so if I'm not maxing my injectors ( plus I have a boost-a-pump installed, not being used yet ), is there any reason I wouldn't run straight water?? Or would you still suggest 65/35 water/alky? And currently on a wideband I sit at 11.5, would you change from that with the 65/35 ratio?

ChevyNo1

Just read that entire article . . . after reading it, I want to reiterate my question above . . . if I do NOT need extra fuel to ease my injectors, do I need any alky at all in the mix??

S_J_H

Your welcome.I tried to dig up as much info on this subject as I could.
You could probably tune for a leaner a-f and run more water but it looks like your engine is tuned nice from the power figures.
I think a little alky is good. To much and then your just running dual fuel types and that gets tricky to tune.
At the point your at now, I would keep the same amount of alky and add more water until all knock is gone.
So try the 15gph nozzle but at a 70/30 water to alcohol ratio and see if that helps out with the knock.

S_J_H

No, I don't think you need any alky at all really. But only a dyno or track session will tell for sure.

ChevyNo1

Cool, I will give that a try!! Thanks again!

- Dug

Jim98WS6

Congrats Dug those are great numbers.

ChevyNo1

Thanks Jim!!! Where have you been anyway, haven't seen you in a long time!! What's up with your car?

Jim98WS6

My car has been an adventure
Spun a bearing last spring at FB. Ran 11.49 @ 121 NA on that run. That's not too bad considfering it's a 422 cammed/tuned and geared for nitrous (I don't have the money for the DP yet). Motor is rebuilt (again!) and back in the car - all I have left to do to fire it up is install the alternator, water pump and radiator. Wish me luck on that initial start up This is my 4th motor
I need new harnesses, a battery, and some break in time before I can go racing again - probably not until the new year.

WhiteDiamond

Dug,

It has been a while since I heard anything about your set up. I am glad to see you are dialing it in. You have a ton more patients than I do!! It was shortly after we moved up here to Colorado that you started this project.

Impressive numbers for street driver!

Todd

P.S. Howdy Jim, haven't heard much about your project since just before you moved back to Arizona.

ChevyNo1

WOW, you've been busy with it, 4th motor?? I'm still on my 1st!

Hey Todd! Good to hear from you! Yea, it's taken me some time to get this far . . . tuning by far was my biggest improvement, can't say enough about how important it is. When I 1st brought the car back I dynoed at ProDyno ( granted, it was like 110 out! ), and all it could muster untuned @ 5psi was something lame like 390rwhp!! Still running the same pump gas and water/alky and I'm now up to 575, motor has not changed a bit. Got bigger injectors too.

Todd, do you still have an F-body??

- Dug

Jim98WS6

Well hi Todd. Long time no talk to Sounds like a nice truck in your sig.

Mark C

SJH, thats a great paper.

For people who don't know, NACA later became NASA.

I just can't believe the amount of water they are putting into the engine. But it must be true.

You guy's want to put a recovery system in your exhaust, and you're my hero.

But, kidding aside, it looks like the detonation control is all about the water. The alcohol was just to keep the water from freezing.

The alcohol, by its heat of evaporization gives lower temps, but that's kind of minor compared the detonation control of water.

The only other thing is that 80 octane aviation fuel is very different (lower) than 80 octane auto fuel. I can't substantiate that, but I believe it to be true.

S_J_H

Well that's what I thought Mark.
Until I read NACA report 812,lol
That was done on a supercharged engine much more comparable to what we are dealing with.
This was the first direct test I have seen with water alone vs other mixes.
They showed a direct comparison of straight water vs 70% methanol/30% water and some other chemicals mixed with water that were even more effetive than methanol.
They used a .5lb additive to 1lb fuel for all tests.
The methanol blend was MUCH more effective than water by itself proving methanol is a potent anti detonation coolant.
Water will stop detonation if you run enough of it.But it takes away considerable potential power as well.

I have proven in my own tests that my car is stronger without any water but needs some serious octane then.
I am going to try a very high flow methanol only system.