Hi all:
I have been playing around with this recently. I have an auto and a V2 with 2.87 (loose BOV @ 10psi max boost). I floored the car at 4th gear, 3k rpm around 80mph and I found out if I give her ¾ of throttle, the car pulls a bit stronger than full throttle. By doing both, it downshifts to 3rd and the rpm jumps to 5000. But I just feel ¾ of throttle pulls a bit harder than full throttle.

Here is some more data…..
@ ¾ of throttle, I saw 5psi on the boost gauge and with full throttle, it is a bit more, 6-7 psi. The fuel pressure @ 5psi is about 70 something and @ 6-7psi(full throttle) is higher, 80psi.


some one help me on explaining this?

My guess is that I am running too rich @ full throttle?

I have a super rich A/F from last dyno, under 10:1.

thx~

 

Weird, I've always told myself I feel the car faster at 3/4 throttle as well.. I'll try looking at the boost gauge next time, assuming there aren't too many people in the way on the road

 

you feel the same too?

hmmm, even the boost gauge read higher at full throttle.


but downshifting 2 gears is another story.....it's a strong pull but it is always to short.

 

Heres my question, how did you floor it on 4th and keep it in 4th at 80mph? You shouldve shifted down to 3rd gear no matter what unless you went above 125mph.

 

Good point.. longer in gear = more boost... have you tried this specifically keeping the tranny in let's say 2nd or 3rd?

 

Hi Dixit, long time no see~

I did mention that she downshift to 3rd in my first post. I have to play around with her, sometimes halt throttle will not downshift. but 3/4 throttle will do.


how's the turbo project going?



sometimes I floor the car at 4th and turn of the OD to keep the car in third longer. But a lot of time I have to let go the pedal because traffic.

 

Maybe because you're not expecting to go faster at 3/4 throttle so you're not bracing yourself, thus making it "feel" faster.

WOT also dumps more fuel into the engine.

 

hi Kevin!

yes, @ WOT, my fuel pressure reads higher. I think the way to describe is that @ partial throttle, it gives a strong pull, but a crappy high end. @ WOT.....it doesnt give a strong pull, but it has a lot more high end than partial throttle.


thx ~

 

Turbo is going ehh. Have problems here and there. Just working through them.

 

one of two things
knock {aka detonation}
too much fuel
10:1 is way too rich. get that sucker on the dyno with a wide band, ste it a little richer on the dyno do to lack of air movement for when you get back on the open road.

tuning the car will cure the problem, along with knock. you can not fully rid yourself of knock

 

Say what?

 

<sigh>I hear you man.....hope everything will get resolved.



not 10:1....under 10:1 (10 is the lowest on the dyno graph...and it went below that)

I dont have anything to tune with.....I will either go for S-AFC or cartech FMU. the later one gets my vote now.

 

I'm having similer issues, maxi-overdose.

First off, what i'm running: V1, 3.125", 8:1, Walbro Hi-flow FP, stock FPR.

My highway pulls feel and have felt really pathetic. So I decided to do downshift into third gear at 70mph and look at my Fuel Pressure gauge. I hit 80psi at ~5300rpm and it continued to rise. Now is it just me, or is that way too rich? It seems like all my performance gets blunted under WOT by too much fuel. What do you guys think? I wonder how much hp/tq I would gain if I could optimize the air/fuel ratio.

 

A dyno session will tell you what you want to know. Unfortunately, until you get something like an SAFC or a Vortech SFMU, you're pretty much stuck with the afr that the calibration disk gives you. A cheap alternative would be a bleed valve.

My experience with using a 6:1 disk with a 3.25" pulley is that it seemed lean, although EGTs never got above about 1475F. But I think I heard some audible detonation on one WOT run to redline recently, so I'm running the 8:1 now that the hot summer months are here, just to be safe.

 

Hi Craigy~
80psi sound about right and to know if your are running rich or lean...like Stephen mentioned, you have to dyno your car or to have a really accurate A/F gauge.


If I floored it at 4th, it down****s to 3rd and my fuel pressure is around 80psi. I am running really rich with my set-up. what rpm were you at when you downshift to 3rd?? where you at 4th gear?

I usually raise my rpm to 3000+ before I boost so I can get more out of it. I found that boosting from cruising at 70mph with 2500 rpm is kinda weak. see....another bad thing about having an auto is that everything is programmed and its hard to adjust to a right rpm with a right speed unless you manual shift the auto. if I want to have fun boosting from rolling, my auto only gives me 3 options....either boosting from 4th 80mph 3000rpm, or 3rd 60mph 3000rpm, or 3rd 20mph 2000rpm. The last one will downshift to 1st and give me a crazy pull.

 

Yeah, dyno!.....


Well, at 70mph I am at like ~4200rpm. Fourth gear is pathetically weak on the highway. I thought at first I was just getting spoiled with the boost, but I am starting to think it's something else. My blower DOES have around 70,000 miles on it. But then again, the internals looked perfect with no leaks and tight bearings. I also spun for almost 3 seconds seconds on my 1-2 shift yesteray, with the tires squeeling like mad. I drifted to the right a bit then when I hooked up the car jerked back straight. Does that mean anything?

 

if the blower can generate boost....then it is a good blower. My blower has some milage too. I think Kevin had 30k on it and I dunno how many miles did Adam (the first owner) put on it. But for some reason......auto from 4th to 3rd gear is weak too. From 3rd to 2nd seems to be more powerful at the same rpm range.

Quote:

I also spun for almost 3 seconds seconds on my 1-2 shift yesteray, with the tires squeeling like mad. I drifted to the right a bit then when I hooked up the car jerked back straight. Does that mean anything?

torque steer?

 

It's probubly the gearing, but still....at 70mph in 4th gear is at ~3300rpm, it should still pull hard, but it doesnt'. It's weak.