OBD2 solutions

[Roger Heflin]

On Thu, 3 Jun 1999, Curtis Mittong wrote:

> Thanks all for your inputs.
> 
> >I dont thing the stock
> >ECM runs into limits, rather the sides of the injectors required to
> >fuel things make the idle bad.
> 
> This is good.  I didn't know that larger injectors made potentially rough
> idles.  Its stuff like this that I need to know.
> 

If the injectors get too big it gets difficult to control the short
openings at idle.  Mine had 22 lb injectors originally (93 Z28), and I
have 30 lb in it now, and it does idle.  I have not yet adjusted the
VE tables to properly setup things for my different torque/hp curve
than stock, so my fuel adjustments tend to bounce around depending on
how far off my tabled VE is from the real ve.   Now my car is doing
370 rwhp with 7.1ms injector times, at 6000 rpm I have open it up to
9.0 ms, so 30lb injectors should be good for up to about 470 hp with
the stock fuel pressure (if the fuel pump can supply that much).
Then the real issue is having someone to do the computer, and that
could get really expensive, since doing it right takes alot fo time.
My car ran a 13.2 before the tuner worked on things.  He got it down
to 12.72, and I have since lowered things to 12.52 by adjusting the
computer more, and based on others (much better) 60 ft times I should
be able to get more out of it, at least .2 on just the 60 ft times.

> >Now maybe if you went with solid lifters and raised the
> >rev limiter to 7k+ you could get that kind of hp, but I don't think
> >most people class solid lifters as streetable, and the engine life
> >with that stroke and high rpms would be severly limited.
> >Now there are a few people getting over 600hp on a streetable Lt1 but
> >they are all using large blowers (close to 20psi or more), or large
> >N2O shots.
> 
> 
> Do you think that maybe 4-valve heads could support alot more accurate flow
> with hydraulic lifters?  I agree that solid lifters aren't the answer.  I
> built a 455 pontiac with solids and the 3000 mile adjustments started
> getting to me.  (it had 522 at the rears, but the constant 104 octane bills
> hurt too)  As far as the RPMs, I couldn't take it over 6500 and feel good
> about the longevity of the package.  I guess what I'm thinking is that if
> 592 is possible with hydraulic lifters, maybe 600+ is possible.  I need to
> find that writeup and give you all the specs on that LT1 that CHP mag built.
> I'm still trying to find the final verdict on the cylinder walls.  I thought
> they were too thin to even go 30-over, but I read about a kit for LT1s that
> was a 414 ci stroker kit that called for a 60-over.  They also have 4.125"
> stroke cranks, but I thought for sure you would be into the jackets
> clearancing that.  Whooda thunk it?
> 
I don't know about the 4 vavle heads, there are supposely 2 LT1 sets
in existance, though I have not heard any confirmations about how they
work.  (Dominion heads?).  I have seen their graphs (dominions) and I
really don't know where our stock heads match up in their info.   My
ported heads are producing more power that their listed brand x heads,
so I really don't know how much theirs would add.

It also depends on whether the 592 number was at the crank or at the
rear wheels.    I believe I can probably get 420-460 hp at the rear
wheels with a 396 with a fairly reasonable cam (224/236-114), and not
too exoitic of heads.   That would translate to somewhere over 500 hp
equivalent at the crank.   

 No ideas what they may be doing to get that big of bore.  Maybe
a different casting.

> >idled beautifully... BLM at 128 and INT bouncing between 127 and 129.
> >WOT was very pleasant as well with the injectors only about 60% duty cycle.
> 
> Ummm.... BLM?  INT?  Big Loud Motor?  Impressive New Trailer?
>

BLM - block learn - it tells how much the computer is needing to
adjust fuel in closed loop.    BLM is the long term, INT is the same
things just done short term.   INTS held over a long term will cause
the BLM to be adjusted.

 > Curtis Mittong
>