Do I need bigger nozzles for my SMC kit?

[Jon01]

Got my SMC kit installed yesterday and was out tuning, I've gotten to 18 psi, the pump speed is at 10, and I'm starting to get a little knock.
I'm not getting ANY bog, even when I set the turn on level down to 5-6 psi!
I believe the nozzles in it are 10's.
Running denatured if that makes any difference.
Thanks for any help!
Jon

 

[Turbo__Tim]

Jon01, sounds about right! It's time to start adding water. Try a 10% mix for a while, then 20%. then 25%, then 30%.

As you go up in water content there will be more cooling, and more tendency to bog. You will begin to see some transitional knock 1-3 seconds into the spray cycle. This will occur close to the optimum mix.

Eventually you should be able to get the activation point up to 12-14 psi, experience light transitional knock, and max out around 21 psi.

It's always a good idea to tune for the most boost, then back off a couple psi to stay safe. Take your time, and let the motor, and it's internals cool down after long runs. An egt gage is a really usefull tool, as it lets you 'see' if temps are getting to the knock point as you continue past 85 mph. Carefully monitering the egt's and knowing where your particular 'danger zone' is (temperature wise)will help you avoid getting knock while tuning.

Good luck, and let us know how you make out!

I enjoy a good 'tuning my alchy injection' story...

 

[blackbuick87]

Isnt "10s" a small nozzle for a single nozzle setup? I think most guys are running a .030. I am running .025 in mine.

 

[Turbo__Tim]

jono1 said-"I believe the nozzles in it are 10's. "

 

[Jon01]

It's a dual nozzle kit, if that makes any difference...
I did some more playing, and when I'm slowly building boost-like in overdrive to pass someone, and it gets up to the kick on point, I can feel a small bog, but otherwise, there is none.
Thanks for the advice Tim, I'll post my results when I get it all tuned in! At this point, I think I may be stuck waiting on my 50's to show up, otherwise it'll start leaning out from running out of injector.
Thanks again!
Jon

 

[blackbuick87]

So where is the first and second nozzle coming on at? The beauty of a dual nozzle setup is you can "tune out" the bog. I get the same thing at 15psi when mine comes on but I am only at 1/3 throttle.

 

[Jon01]

I don't think you can set it up so the nozzles come on at different pressure levels with an SMC kit...
Needs to stop raining here so I can go back out and play!!
Thanks for the help!

 

[TRDirks]

FWIW, The jet sizing is being done in two different ways. Some Kits like the BGC and JC kit use Nitrous jets which are numbered by the size of the orofice in the end of the jet (ie: .030 is a jet with a hole that is .030 of an inch). On the other hand is the SMC kit, and possibally others that I am not aware of, that use Chemical misting nozzles which are numbered (5, 7, 10, 15) according to the Flow in Gallons per Hour at 100 psi. So the number 10 jet mentioned is a 10 gph @100psi Jet.

Now the next is how do they compare? That question I can not answer. Someone would have to either test the flow per hour of the nitrous jets or measure the hole in the Misting nozzles. Personally I am not that interested in comparing the two to do the test but maybe someone else has or will in future.

HTH

 

[blackbuick87]

If you really want to know, contact Steve Hill. He has tried both and many others I am sure

 

[Chuck Leeper]

DUAL NOZZLES??

I think there was only 1 dual stage kit made by SMC and I had it for a test.. Recently sold..
If the pump speed is already at 10 w/ dual nozzles and the knock is getting there at 18psi.. then I'd be looking for something else causing the problem.. Like poor gas octane.. not really 93.
Adding water will help some, but w/ the speed already wide open, you have little to tune with, short of nozzle changes...
FWIW, Steve has some #15 nozzles..
for the flow #'s, search 4 a post I made sometime back that detailed the flow tests I ran on the current SMC system.

 

[Turbo__Tim]

Here is the link to Chucks' post.


http://www.turbobuick.com/messagebd

Jon, I'm suprised you could lean out with the combination you have. Tho you don't list an upgraded fuel pump, I'm sure you have one. For $50 you can get the Postons fuel pressure guage that can be taped to the windshield to test WOT F.P. Anybody running these kind of boost levels should have one.

When My fuel pump died, it went slowly, over a period of time. Drove me crazy trying to figure out where the knock was comming from.

I think you will be happy with the 50's.

Good luck!

 

[Jon01]

I've got a f/p guage on it, and pressure doesn't drop off, the o2's never get below 800 but they do fall off through the run, but I don't want to run it on the edge.
It's got a 340 in it.
Hopefully the 50's will show up this week and it can get turned up further yet
I think that the 26* race chip in it is partially responsible for the knock.
I have NEVER seen 93 octane gas around here, 92 is the highest we go for regular pump gas.
With the weather being hot and sticky, and school starting tomorrow, I'm not going to be able to mess with it till the weekend, but my goal is to get the injectors in it Saturday and do some playing with it and see what happens from there...
I'll update further when I get something accomplished.
Thanks for the help guys!
Jon