Thanks for the info, but here's some more questions. Since you are using the dual nozzle system I am assuming that when you changed fuel jets you went from a .022" to a .028", if so that is way too big of a jump. Get some .024" jets if you can, I think that would be a good middle of the road jetting pattern as far as running rich or lean. Also, when you said the fuel pressure dropped to 25psi, did it stay there or did it climb back up? Since the words "gradual" and "dramatic" are relative to the person using them, do you happen to be able to tell how long the lean spikes lasted (in time or rpm)?

 

When the system activate the fuel pressure gauge reads about 25 PSI and stays there until i shift to another gear.

Thanks, Ill try and find some .024 jets

 

So why the hell did I buy a racetronix setup? My stock pump handled 570 at the wheels with no problem! My racetronix actually is handling my first stage now (which is a 200 shot) that put me at around 643 to the wheels, but it didn't like adding the second stage on top of it, hehe! But on to my point, you'd think that if the stock pump can handle almost 600 horse to the wheels, that the racetronix would handle a lot more than it does, just my opinion though.

 

I wouldn't count on that stock pump supporting 570 at the wheels for long. I look at the fuel pump upgrade as a cheap insurance. $$ for the pump now or a lot more $$ later when the stock pump fails and takes out the motor. There are exceptions to every rule, but play with fire and chances are you'll eventually be burnt.

To the person that started the thread, I would double-check the FP gauge. It sounds like the readings you are getting are not accurate.

Matt

 

Matt, any word on the return at the rails/reg kit for the vette, from Racetronics? Hook me up, I'll take one of the kits? sorry for cutting into anothers post, but may be usefull to others in the pump problem area.
Robert

 

I haven’t heard any solid dates yet.

 

570 with the stock pump??? LOL...your crazy man!

Thats the most I ever heard of. It must have been giving every last drop.

Anyways....the limits we throw around here...like 475-500 on the stock pump are with a margin of safety in mind. Not to mention not many are willing to actually find the limit. Same goes for the Racetronix and Walbros. I have used a Walbro/hotwire kit/Caspers voltage balster for 725-750 rwhp about three or four times without inceident. The pressure drop on spray is usually about 5 psi at that HP. Not perfect...but there is still room. And AF stays rock solid. Including one pull that was about 740 rwhp all dry through the injectors. AF was rock solid.

 

Oh I hear ya dude, I had the racetronix setup sittin around before I even put the motor in, but just never got around to puttin it in, and went and had no problems on motor, added a 100 shot and still no problems (which netted me the 570rwhp), ran it for a while on the 100 shot, then tried the 150's at a dyno day with a/f meter in there to see if the stock pump could handle it, and she didn't like it very much, she started off ok and then went pretty lean so I let right off, but still got 592rwhp before I shut it down. Then I said ok, time to put the real pump in so I can start upping the shot! And the racetronix handled both stages for the few seconds it took to make the dyno pull, a/f was at 10.1/1 on both kits and then started to lean out a little at the end of the pull when gettin close to 7000 rpm and went to like 11.0/1, but I figured it was just cuz I was gettin up in the rpms, but I guess it just can't keep up the fuel, cuz when I went to the track, it handled it for first gear and that was about it, right after hittin second, she burnt up a plug and I let right off when I heard it start to break up. My laptop had broke, so I had no datalogging to look at, but she definately went lean, i'm sure the racetronix didn't like 713rwhp (through a turbo 400 no less) under load, hehe! So that is why I need a standalone!

 

Yeah, I know i'm crazy, hehe (and that number was through a t400, wonder what that would've been through a 6-speed )! I could definately tell the difference though, cuz I had always been told that the tnt kits run real rich, but when I was hittin the 100 shot with the stock pump, o2's stayed the same as on motor, maybe slightly richer, like 920's/930's instead of 900's, but when I put the racetronix pump in, no changes to tune, she started goin way rich, but motor tune was perfect at 12.8-13.0/1! But from what i've heard from all the guys sprayin 300+ hp, you want the a/f to be around 10.1/1 area, so that's fine. On the first stage tnt 200 alone, it drops below 10.0/1, but when I added the second stage dry, she went to 10.1/1 and then like I said, just started to come up a little toward the higher rpms (which I think the pump was starting not to be able to keep up). Once I get the standalone, i'm gonna have to grab a wideband so I can keep an eye on it and see where's it's at, cuz I am scared to put the car back on a dyno, last time I took out second gear in the turbo 400 cuz I shook the tires on both stages.

The other funny thing, I think if I put the 100 shot back in there now, that I wouldn't run as good as I did when I had the stock pump in, unless I started messing with the fuel jets to lean it out some, cuz I went 10.20's @ 134.xx on the 100 shot with stock pump, and when I put the 150's in with the racetronix and how rich it runs now, I only gained 2 mph and went 9.95 @ 136.xx.

By the way, what a/f do you recommend for a 200 - 300 shot, am I running it way too rich at 10.1/1, is there power left on the table making it leaner w/o being dangerous?

 

I have usually shoot for right around 11.0-11.3 to 1 on a 300 shot. It does make quite a bit of difference. I have done direct ports or other setups where the AF would go from 10.0 and gradually rise to 13.0. You could really see the power jump as AF approached 11.0-11.5 and then fall back off after 12+.

 

And is that 11.0 - 11.3 to 1 on a dyno with a wideband, or under a wideband under actual load and with air crammin in the motor from the high speeds? Cuz I heard in the real world, you should be 1 point higher than on the dyno, not sure if that's true though. Maybe i'll have to start messin with the jets to try and get it up to 11.0/1 area if it really makes that much difference. How much hp diff do you think it would make? Put 713 to the wheels @ 10.1/1, you think it would gain 30 - 50 to the wheels (like maybe put it around 750 or so), or is it not that much diff?

 

Al was that 11.0/11.3 running a high octane fuel? What's your opinion on 11.5/11.7 and some 100 octane/93 octane mix for a 250/300 shot, as this is where I am shooting for right now. Actually, my custom fuel curve is 11.7 starting, with 11.5 at torque peak, then going back to 11.7 at redline, so now I am just going to add a mix of fuel, what do think, would you go a little richer? Total hp will be about 600 or slightly higher, and timing is currently at 22*, which I will likely lower.
Robert

 

That's a good question, I run 93/104 mix, so would it be bad for me to lean it out a little?

 

Good point Robert....that was on C16.

When I used to run a 300 shot all dry for about 715 total I could get away with 100 octane unleaded and it seemed to like the AF a lil higher...maybe 11.8 or so.

As far as on the dyno and at the track..I alwasy just used the dyno to get close. The made small changes at the track to see what worked.