link between nozzle and grate

[porksword]

Well at the end of my testing today I decided to try something.

I tested my 800 grate and 1200 grate back to back just like last week and once again it was a .9 mph difference.

Then with the 800 grate on I decided to bore my nozzle from 85.4 to 86.2. I gained 40 rpms but I lost 0.4mph. (I guess I went to far .)

Then I put on the 1200 grate and it was the same speed as before but did gain 40 rpms.

So by boring the nozzle I closed the gap between the 800 and 1200 grate by .4 mph and the 1200 is now only 0.5mph slower than the 800.

For top speed though, Im .4mph slower than I was before I started.

I just thought it was interesting.

[KirkF350]

I see these results as positive, maybe because I like the 1200 grate better on my ski. Plus 40 more RPMs isnt to shabby either.

[porksword]

Yep, they are positive for the 1200 grate. Since I run two different setups I am thinking about seeing if I can go a little farther without loosing speed with the 1200. Then get another 85mm nozzle to go with the 800 grate for speed runs.

I figure since I change grates around I might as well change the nozzle also and get the best of both worlds.

[NateGP1300R]

So, now, with the 1200 grate, and the 86.2mm nozzle, you are .4 MPH slower than you were, but picked up 40 RPMs?

[porksword]

With the 1200 grate I am the same speed that I was with the 1200 grate before the nozzle bore and I gained 40 rpms.

With the 800 grate I am .4 mph slower than I was before I started.

The 800 grate is still .5 mph faster than the 1200 grate but thats a smaller gap than the .9 mph that it was.

[injected2stroke]

Last Friday I went out for a little testing on my GPR I also was looking for some RPM's. In an attempt to accomplish this I also bored out my nozzel with very similar results bored nozzel from 86.39 which is where it was from the factory to 87.07 gained about 40 rpms went from 7080 to 7120 with a 1200 grate but lost an unbelieveable 1.5 Mph and on top of this had my resident bad boy RXP guy kickin my ass. Up here the 800 grate is not an option we drag race or are in 2 ft. or better chop. I had already preped a new nozzel that I got off of Osidebill that measured 85.15 and installed it rpms came back down to 7080 mph was back. I was hoping to pick up more like a 100 rpm's but no luck with that. But I do think in the heat of the summer when the RPM's get to low and detonation becomes a factor this is a good way keep your RPM's up better loose a little MPH that to loose a motor.

[Duke]

What were the rpms Pork?

[WFO]

So Porkmaster...

Did you check the rpm difference between just swapping the 800 to 1200 grates ?

[porksword]

My 800 grate always runs 30 more rpms than the 1200.

The rpms were a little low to start to day for a different reason but before increasing the nozzle size I was at 7070 with an ocasional 7080 with the 800 grate. Which would leave the 1200 grate @*7050*. (the one piece of info that I forgot to write down) however I've seen the same result time after time (30rpm difference).

After the nozzle size was increased the 800 grate was @ 7110-7120 and the 1200 grate was 7110.

So It looks like the 1200 grate actually gained more rpms than the 800 grate did also with a total of 60 rpms gained on the 1200 and 40 rpms gained on the 800.

[porksword]

That helps explain to me why some guys are getting different results from nozzles. I would venture to say the guys that are running 1200 grates are having better #s with the 87mm and the guys running 800 grates are having better #s with the 85mm nozzles. However Im sure when HP is increased dramaticly through porting or BB these results "could" be different.

My setup is single pipe EFI 1300 with pretty much everything but porting.