OBD2 problems

[Roger Heflin]

On Wed, 2 Jun 1999, Curtis Mittong wrote:

> Whoever has knowledge of this stuff may want to contact me offlist.  I have
> alot of dumb questions that are probably below your intelligence levels and
> I don't want to clog up the list with too much "entry-level" chatter.
> 
> Background:  I have a 96 Impala SS.  I plan on making the LT1 into a 409
> (4.030 x 4"...which actually makes 408.17) and totally starting from the
> ground up.  I am tired of bolt-ons that make a certain HP, I want to tailor
> each part to each other part and get a good reliable streetable engine.  I
> am planning on output being in the 600+ hp range.  I can build bulletproof
> engines that put out 1000 on nitrous with enough money and resources, but
> what I lack is the electronics know-how.  I have the mechanical plans done.
> Currently, in my little burg there is no emissions testing, but I don't plan
> on living here forever, nor does my little burg plan on never testing, so my
> baby needs to be street legal (or have the potential to be once a year).  I
> have seen an LT1 with a stock PCM and an Accell piggyback make 592 hp, but
> that was with the stock Optispark and it was pushed to the limit.  Its hard
> to get the PCMs to reliably support more than 500.  I think with the right
> tuning, I could get 650hp to pass a sniffer, but without OBD2 compatibility,
> I'm not technically legal.
>

I think there aren't alot of people that could make a computer
controlled drivable engine with the stock ECM.  I dont thing the stock
ECM runs into limits, rather the sides of the injectors required to
fuel things make the idle bad.   I am not really how sure I believe
that as my 350 Lt1 is driving 30lb injectors just find and the idle is
just fine (after quite a bit of adjusting).   I think the other issue
is with radical changes you need to change more than just the WOT fuel
table, you need to properly adjust the VE table for things to run
good, and this takes alot of time to do properly.
 
> 1) Someone with emissions knowledge; what do they check and is it all ok if
> it passes the sniffer?  Or does it have to be a certain configuration?
> Certain hardware intact?
>
Well, they will do a visual inspection before the sniffer, and if the
visual inspection fails they won't do the sniffer test.   Usual
failures are missing cat and similar obvious things.  I really dont
think anyone would notice the computer being added on to or replaced
if things were not obvious.

 
> 2) Since Iive where they don't check, does that mean that I have free reign,
> or is it still illegal but no-one checks?
> 
> 3) Is there maybe an OBD2 computer that will easily support that much HP?  I
> want overkill, not just squeezing out 642hp.  I may want to add nitrous or a
> blower later.
>
I would not suggest adding N2O or a blower wit ha 409, the cylinder
walls are supposed to be too thin to support that sort of thing for
very long.

 
> 4) Is "emissions legal" as easy as using "street legal" or CARB approved
> parts?
> 
> What I really need is someone to take my hand and walk me through this.  My
> main problem is this:  I can take my parts to the machine shop and get what
> I want and I can build the engine to support the HP.  But, if I take it to
> my "EFI guy" and he says that its not set up to best use the EFI he had in
> mind, then I have already failed in tailoring all the parts together.  I
> want to know enough that I can make accurate plans to make compatible
> systems work best.  It can make the difference between a few extra HP and a
> detonated engine.  Thanks
> 

I don't thinkg there is any tuning of the engine to the EFI there is
adjusting the EFI properly to run the engine, and I really don't think
the issue is with it being possible, it is with someone knowing how to
do it.  Tuning takes along time, with DFI or the stock ECM, the only
real way to eliminate most of the tuning is to get wide ratio O2
sensors.   Also I don't think ou will get that kind of Hp out of a 409
and have it streetable.  I am pulling 370hp(rear wheel) out of a 350
Lt1 in a 93 camaro, I would be able to get somewhere around 420 out of
a 396 in a streetable config.   You could add a bit wilder cam and
make it harder to street and push the torque curve higher, but that
would probably only give you 10-15 more hp.  Better heads 20-30 more
hp, and better headers and exhaust than I have would maybe get 40 more
hp.   So about 440 or so from a 409 and add 15+30+40 and you have 530
or so hp.   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.

 > Curtis Mittong > 
> 
>