Welcome to the Corvette Forums at the Corvette Action Center!

Adjustable fuel pressure regulator: good mod?

S

sothpaw

Guest
What do you guys think about this mod
on the LT1/LT4? Assuming that the stock
pressure is within the acceptable range
(?37-45 psi), will upping it give you better
performance?

What's the fuel economy effect? If the pressure
is always higher, would you use more fuel
at idle and cruising (1400 rpm for me)? I would
think so.

Do ya think the stock or hypertech chip would simply
compensate by decreasing the injector open time so that the fuel/ air
mixture is same (no hp gain in this case) at WOT?

Has anyone actually done this one on an LT1/4 and
seen good results? If so, was this a stock car?
 
T

tom_85_vet

Guest
My suggestion is to determine a plan for your car. How much HP increase? The adjustable fuel pressure will only help if you have made major changes to the engine, but it will give you a little more controll and yes the computer will adjust the fuel pressure.

I have an 85 and I am limited on the computer chips. I understand the LT1/LT4 chips can be programmed to your specs. If I had a LT1/LT4, I would develop a plan of mods for the car and then get a chip programmed specifically to my car.
 
S

sothpaw

Guest
Tom,

I have the plan. My goal is to break the 13 s mark. Now,
already at 13.3, and I have done this by changing to
roller rockers like the LT4 has, and by various induction
improvements which I think the LT1 will /is responding to.

To get more air/oxygen in, I have a free-flowing SLP intake,
coolant bypass in TB, and TB airfoil. It's the concensus here
that a larger TB wouldn't help because of the intake runner/head
size on the LT1.

I would like to reach 12.9s at minimal expense and without hurting
fuel economy. So before turning to headers/exhaust, I wanted to
explore what else I can do at minimal cost under the hood.

If I got .1 sec out of the AFR I would do it. But obviously,
I wouldn't if it destroys the economy or does nothing.
 

jstkrsn

Well-known member
Joined
Jun 3, 2002
Messages
59
Location
Parrish, FL, USA
Corvette
1992 LT1 White Conv.
Biggest noticable change I've had so far was when I put the 52mm TB in. OPening up tha air box and putting a K&N filter din't do much because the restriction was in the TB. Now it revs freely to 5700 rpm.
 

Ethan

Well-known member
Joined
Jul 14, 2001
Messages
68
Location
Elgin Tx. USA
Corvette
1991 L98 Coupe
Adj. regulator

I have heard that on astock GM chip you can lean the motor out a little a get more power because GM runs them alittle fat(rich) for warra.nty reasons
 
S

sothpaw

Guest
JSTKRSN,
Was that with the stock LT1?
I asked around here and not 1
person advised it or tried it with
the LT1. All said the intake/cylinder
heads would be too restrictive.

Do you have dyno numbers?
Have you tried the 1/4 mi
before and after?

Thanks!
 

jstkrsn

Well-known member
Joined
Jun 3, 2002
Messages
59
Location
Parrish, FL, USA
Corvette
1992 LT1 White Conv.
I've added the 52mm TB to both a L98 ('86) and a LT1 ('92), and both made a noticeable difference. I have no time or dyno records, but you could really feel it. The 86 had only a K&N added. The LT1 has Borla mufflers, K&N, open filter top, and Hypertech Chip. I don't understand why some think it wouldn't help.

Jim

By the way, how do you add a picture to responses?
 
S

sothpaw

Guest
JSTKRSN,

The explanation I heard was that the intake
runners and cylinder heads can only use so
much air every stroke. It makes sense to me
that there must be a weakest link in the original
system--whatever passes the least air volume.

These guys are saying that the runners/heads
are weaker than a 52 mm TB, fairly well matched
with a 48 mm TB.

All agree that with ported heads a 52TB would help.

But these guys never actually tried it on the LT1-you did.
I'm not sure if they really knew what the LT1 heads / runners
could pass.

Some guys did say they tried the 52TB with the L98 and it
didn't help. This engine is supposed to be even more restrictive
than the LT1.

So you felt the same extra kick from the '86 and the '92?
 
S

Shadowing1985v

Guest
wait a second

how does ram air help the engine when changing to a 52mm won't do anything

cause dones't ram air shove air faster through the intake?

oh wait a second, maybe i do understand

maybe there is a differance to how fast it goes in,, then to how much at a time u can shove in


so that the top of yoru heads will fill air into it much faster is that right, or what??
im trying to learn
 

Mad-Mic

Gone but not forgotten
Joined
Feb 12, 2002
Messages
1,853
Location
Annapolis Maryland
Corvette
1987 Redskin Red Coupe
hmmm......

i would say a good polished 52 mm thottle body and a hipo cat converter would be the next step in seat of your pants feel for mod changes with out getting too pricey on intake goodies but that would be the next step in a n/a motor. if my mem serves me correctly you already got muffs on it :)
 
Joined
Jun 20, 2002
Messages
2,509
Location
Tallahassee, FL
Corvette
none right now :(
If you look at the LT1 intake, it is actually built for a 52 mm throttle body, not a 48 mm. The 52mm does help, but it won't work miracles... When you talked about your roller rockers being like the LT4... does this mean 1.6 rockers all around? If this is the case, you could benefit more from the larger throttle body than the standard 1.5's. (this is due partly from the larger lift, and partly from the multiplication factor of the camshaft x rocker lift, which actually mimics a mild cam change, and would increase your high RPM HP) You will definitely gain more HP from an exhaust change... I know part of the problem with Corvettes is the high cost.... I personally got my mufflers cut out for about $100, they kept the factory tips so it looks stock (doesn't sound stock though!) If you want it quieter, I have heard that you can cut out the center resonator for a big HP increase, with a less noticable sound increase, but I haven't done it so I can't be sure... hope this helps
 
S

sothpaw

Guest
From what I am getting here,
the 52mm TB might do something
afterall. I know it wouldn't be
as good as exhaust, but exhaust
is more expensive and louder.

I have a book with a dyno tested
camero LT1 that gained 12 hp/8 ft-lb
with the 52 mm TB, but that was
AFTER ported heads were added (gained
at least 25 hp on the heads alone).

So there's no prayer I could gain more
than 12 hp for $300 spent in parts.

--I think I'm going to try an MSD multispark
ignition first, about the same cost as the TB.
What do you think?
 

Mad-Mic

Gone but not forgotten
Joined
Feb 12, 2002
Messages
1,853
Location
Annapolis Maryland
Corvette
1987 Redskin Red Coupe
i'd go with .........

the throttle body. but just remember this the more hp you make the less you will notice. 12 hp in a motor is either hot or cold. like at the track when you stage at 165 watertemp and a 220 watertemp. not much difference but lets say optimum watertemp for a launch is 165 and for every 1 degree over 165 is a 1 hp loss (i'm not sure the right calculations but its something similar) that equates to 55 hp lossed to heat. now 55 sounds a bit dramatic but take in account atmospheric conditions. and it's right close to the hp mark ( hot 95 humid 85% day with a 220 water temp at launch you would notice the 55 hp loss. compared to a 60 cool night with only 45% humidity with a 165 degree watertemp and you gain it back) although you can compensate for a hot tune up and gain some of that hp back, not much, but you can. i'm sure you noticed these conditions before cause these are more tempermental ?sp...lol :) (injected cars) to humidity. a 12 hp increase won't be noticable till you start taking in the whole equation and A. either buy a portable weather station for logging data from weather and water temps and shift lights. or B. find a place to do some dyno runs while the car is in it's optimum water temp, most likely 165. just don't like to see someone chase their tail and trying to find out or more less what to expect and maybe getting let down on making a hp upgrade decision. but with either one of these if you keep hopping it up in the long run you will see that 12 hp increase for either one you end up making here. most likely you won't notice till you get full exhaust and your intake done then things start coming together.

Good luck let us know and i hope i'm at the track when you bust a 12 out on trance.....hehe :D
 

Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors

Dealers:

MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Parts/Accessories:

Vetteskins

Advertise with the Corvette Action Center!

Double Your Chances!

Partners

Top Bottom