Dyno graphs.

RonA

RonA

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Feb 26, 2008
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With a p-pump where does hp usually start dropping off and what causes it to drop of quickly? Looking at some of my graphs it looks like 3000-3250 or so is where it starts to fall. Seems like a larger primary falls of a bit later. I have a 4k gs kit, Helix 2 cam and PDR Stage 2 head. Is it a cam issue, fuel issue, air issue, or a combination of the 3.
 

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Are you running aggressive tires ? I see the smoothing was on 0, my runs with my factory lift pump looked the same. Fuel supply is my problem. Mine nose dives at around 3200-3400
 
GSK. Mine with the 4k kit peaked around 3k as well. With it tightened down a little more, it fueled a little further out but the idle sucked.

0428dyno.gif
 
Ron, I have seen my peaks higher than that, my best number was with a pump issue and caused to to be late, even with 4K's my max T/Q was at 3100 and Max HP was at 3400, this was with 24 degrees timing.

I've been thinking about that question you asked too.

Jim
 
Tires aren't really aggresive. Last time i checked my fuel pressure was between 40 and 45 at wot. I will double check the fuel pressure. My idle was nearly perfect before i put the 022's and .120 dv holders in. I may be able to tighten them a click without problems after I put my 181's and stock dv holders back in.
I don't mind trying a 5k kit if it might help. I hear the one from CDS is good.

I just received a set of 6x.016 injectors. They told me to add a bit of timing(going from 19 to 23). My current injectors(mach 7's) are about 6x.012.
Jim.
You'll chuckle when you see what I'm doing to my afc. I haven't had any luck finding a spring that is stiff enough without coil binding, so i am making a new diaphram cover with a piston in it to move the afc arm. The diaphram will still be there, but will just act as a seal. The piston is smaller in diameter so I can use a light spring and still slow the fueling down. More trial and error.
 
RonA said:
I don't mind trying a 5k kit if it might help. I hear the one from CDS is good.
Click to expand...

I haven't dynoed mine yet...but they drive very nice, and seem to fuel out past 4500 pretty hard.

Dyno well tell for sure though!

Chris
 
If I can get it to fuel to 3400-3500 before backing off, that will be plenty. I don't pull and the extra rpm isn't needed.
 
RonA said:
You'll chuckle when you see what I'm doing to my afc. I haven't had any luck finding a spring that is stiff enough without coil binding, so i am making a new diaphram cover with a piston in it to move the afc arm. The diaphram will still be there, but will just act as a seal. The piston is smaller in diameter so I can use a light spring and still slow the fueling down. More trial and error.
Click to expand...

I would like to see that.
 
A Gov spring works good too, problem is I don't have one as I gave 2 away.

Jim
 
Jim Fulmer said:
A Gov spring works good too, problem is I don't have one as I gave 2 away.

Jim
Click to expand...

I can vouch for that..:thankyou2: I have an invatational pull this weekend and will try it with the #6 plate forward, it is awesome at low boost (as well as can be expected with a "66") It seems to max out by the limit of the diaphram material, remember to leave the spring as loose as it can go because the more you tighten the spring the less travel you have because it threads in from the foot side.
 
Glad it worked out for you, that setup seems to work great, next inline is a #6 with a 215 pump spring.

Jim
 
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