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L31 Guys come here, 1996 stock SBC bitten by the mod bug

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l31 yukon
20K views 58 replies 10 participants last post by  Hogg 
#1 ·
Hi Everyone here !!!
Performance bug has bit again, with great success we modified a
stock L98 with a set of AFR Heads, Accel/Lingenfelter Super Ram intake
and all of the proven LPE Combo.

This time we have a 1996 Yukon and we plan on give some power to the
1996 stock L31, We want to keep thing simple but the cam/head selection
might be a bit difficult.

First thing we will do is put a set of 1 5/8 long tube headers.
http://www.summitracing.com/int/parts/pte-h8059/

Since is a Vortec, we think the best head is AFR0912
http://www.summitracing.com/int/parts/afr-0912
65cc to bump the compression (for the cam)

We will add a true roller timing set
and a set of 1.6 or 1.5 (not sure) full roller rocker arms.
Brand new set of Lifters
Chrome Moly Pushrods

Here comes the difficult part :
We love the kickass sound of the Big Mutha Thumpr camshaft
We already know that most of them are more sound that performance
but we are using the Yukon as a cruiser and won't be hitting the track
at all but we would love more power there.
Here's what we got : COMP Cams: Big Mutha Thumpr™, 299THR7 <BR> Very Rough Idle, Street/Strip
For Chevy 305-350 c.i. Cyl '87-'98

We have the stock injection, will not go carb.
We have the stock intake, but looking for the upgrade.
We might upgrade injectors as well. no problem.
We might need high stall converter no problem, 2800-3200 Vigilante
will make the trick. We don't want to touch the gears we have 3.42.

What do you think of the Head selection?
What about the thumpr camshaft?
Intake/Injector upgrade or should i leave it stock?

Thanks in advance !!!
 
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#38 ·
i wish they could produce (i dont think it will happen at all)
a good aftermarket intake, the marine conversion is too much.
IF i find one ! pretty hard to come across.
VMAX+TB Spacer will make for it , at least a little bit.
We plan on using PCMForless.com

As for the exhaust, no cats and true duals.
 
#41 ·
You can remove the silencer box with no problem & just plug the opening in the TB hat.I have mine plugged but the left the box on.Not a lot of options out there becuz you have to have the MAF in the airstream.Some S10's used the same style hat w/o the box,therefore no opening to plug,but,I can't remember which year model.There is an aluminum hat that can be used if you can find one.They were used for whipple SC apps.Most ppl just remove the box,paint the hat.Some mount the MAF @ the TB then use a K&N out to 1 side.Cold air intakes look better,but,don't really offer any performance gains.
 
#47 ·
So just to interject meaningless drivel, I'm always with tech when it comes to making changes to a giant pig of a vehicle in the name of speed....seems pointless. .....however
Met a lad 2 weeks ago and spent some time with his 06 Denali....again, 5500#+ truck..... drives it daily, runs mid 10's
Open hood, 572, canfield heads, 1000cfm Domimator. Huge Solid roller, TH400, custom 4000 stall, gv od, 9" rear.
Truck looks stone stock, and whoever tuned the Carb and timing is a genius, drives really nice and a claimed 10mpg
Again, looks stone stock, and I know my 06 avalanche with a 5.3, a tune and a cat back exhaust with 35" tires never got better then 10-12mpg
It only takes money lol.
That my pointless contribution.
 
#48 ·
#49 ·
Thanks Hogg !
First of all, the intake alone looks like a lot of $$$$
$1,365.21 for the manifold only, plus we have to get the rest.
Maybe down the road but not sure if it's worth it since it's no
race car but, might help a lot with the power.

We don't have the 0912 heads yet but we are sold to AFR
Here some pictures of the L98 heads i used to upgrade my 87 Vette
and they are a piece of art, so that's why we chose to use AFR again
for the Yukon.


Comparison with the stock 128 Alum head:

 
#50 ·
Thanks for those, but whenever you get the AFR Vortecs heads and you remember.

I wouldnt even consider buying any marine intake stuff new. I did my complete crossram for CA$1000 including tuning. Just the parts would have cost US$4000 if I bought new.

Even this dual plane Vortec marine intake would be better than stock. I'm told you can find them for $300 complete.



Thanks man.

peace
Hog
 
#51 ·
$ 1000 is a great price for a complete set up !
Paid $ 1500 for the complete Super Ram years ago (for the vette)
I would have loved to use a Super Ram or TPI for this Yukon
but too much involved with the computer etc.

Please let me know more about that $ 300 complete Vortec intake
that is a steal ! Looks like the Edelbrock aftermarket units.
or maybe im wrong but those goes for $ 4000 (complete system new)

I know the intake is the limitin factor here, i was surprised to learn
that no company has offered some kind of upgrade for our trucks.

:confused::confused::confused::confused:
 
#52 ·
The $300 would be used off of ebay or something.

It is mentioned here. its a cool little forum all about our trucks. I'm Pauly over there.
"Carb" style manifold W/ MPFI discussion

I paid around $600 for my crossram intake, it came with teh marine 25 lb injectors, a few dollars for fuel attachments. The install kit even came with GM colour coded injector wiring, the guy even drilled the water pump bypass for us.
Even with the stock tune (injector flow rate changed of course) I noticed a seat of the pants gain in off idle low rpm torque and upper rpm power, on a bone stock Vortec 350.
This was backed up by FAST355 when he did some dyno testing aftyer his conversion.

peace
Hog
 
#55 ·
The Ramjet is a really good option for you.The entire kits are pricey,but,you can buy a new Ramjet intake for a lil over $500.The rest can be pieced together fairly cheaply.You can put 1 together for $1000 to$1200.Cheaper if you shop wisely.You already have the PCM,crank signal,etc. That will give you 1000 cfm fuel system that you can swap injectors to suit your needs to & IMO,it just looks cool as heck.
 
#57 ·
Yes.That's the one.It's about $2300 thru GM w/ a MEFI4 controller,which you do not want.You really only need the intake,fuel rails,injectors,regulator.Most everything else you will need is already available on your vehicle.You can do the same thing using an Edelbrock ProFlo XT as well.
 
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