TBI help

I need more power for my 1988 4 wheel drive 5.7 engine. I just rebuilt the engine and installed a towing cam ( helped bottom end torque ). Are there any power adders such as super chargers made for this TBI engine, if so...do I need to do anything to my stock TBI...??????? By the way the engine is totally stock except for to cam. Thanks for the help.  

Any changes you make to TBI engine requires a custom chip for the computer.

To bad you didn't contact this column before rebuilding as a lot of power can be had with a few component changes without resorting to a blower. The cam is a step in the right direction, though the swirl port engine can take a lot more than a RV cam. Swirl port heads work well on a slow turning engine, say 2000 revs at 70 mph which is attractive to a mild cam. However, if you're geared stiffer, say turning another thousand revs a hotter cam like Comp 268 or 270H is a good choice with TBI.

 Factory design full dish pistons leave a lot to be desired as their squish/quench is weak at best. A lot of power can be had with a flat top or "D" dish design that allows more compression without detonation. The head and the piston shape work closly together, I'll get into that in a bit. 

The swirl port heads really need replacement especially if you've got some gears, they work pretty well at low revs but are a choke point once you get over 3000 and die out by 4000 revs. There are many choices that are much better in terms of port flow, chamber swirl, compression tolerance, etc. Vortecs are a large improvement to power with economy and reduced emissions if you don't live in California, which won't permit them without also installing 96 and up emission systems; but there are many aftermarket heads that also provide these benefits and are legal substitutes for the Swirl Ports.

Head chamber design and the piston crown shape need to work together. The heart shape chamber typical of the Vortec design works very well with flat top pistons, actually this is good for any Chevy head. The next most desireable is the "D" dish if reducing compression is a concern. This combination keeps the squish/quench deck close to .05 to .08 inch clearance at TDC. Anything wider significantly reduces the effect of both squish and quench. The loss of squish, which is compression induced turbulance,  results in needing more timing lead, gets poorer fuel mileage and increases emissions. Quench is  the resistance to detionation where the chamber design absorbs excessive late cycle heat, think of it as mechanical octane.  The lack of quench occurs because the greater volume to surface area does not sufficiently control end burn temperatures making the engine more likely to detonate. Actually there is a double whammy here where detonation is concerned in that the lack of turbulance requires more spark lead which increases burn time before TDC, this leads to a pressure and temperature spike at TDC which can cause the remaining mixture to spontaneously ignite. So you get two opportunities for detonation on each and every power stroke when the squish/quench deck does not close to less than about .1 inch as an absolute maximum and .05 to .08 inch is significantly better.

Oh well blah, blah, blah; this can go on for a long time. Here's some extra credit reading:

http://www.chevyhiperformance.com/techarticles/46320/index.html

fficeffice" />> >

http://www.chevyhiperformance.com/techarticles/46326/index.html

> >

http://www.chevyhiperformance.com/techarticles/46359/index.html

> >

http://www.chevyhiperformance.com/techarticles/46364/index.html

> >

http://www.chevyhiperformance.com/techarticles/46370/index.html

> >

http://www.chevyhiperformance.com/techarticles/46438/index.html

> >

http://www.chevyhiperformance.com/techarticles/46461/index.html

> >

http://www.chevyhiperformance.com/techarticles/46467/index.html

  Bogie

just think as if the tbi is the same as a carby but there is a computer that works out the amount petrol you need to mix with the are 1 or more things you can think of the way the that might help

1 incress presure or larger injetors will get more petrol in there.

change the intake maifold might help but talk to some shops that might help

if you place on a supercharger you might be better of to go for a multi injection or a nothere that uses all the inputs that you have and help the stock computer  

I think your next step would be vortec heads or world products has some.I personally would try to stay with smaller c.c ports (intake ,Exhaust) .The reason I say this is because your truck is not like a vega or something.It has some weight and I feel you need to sacrifice top end horsepower to have as much low end torque.Even if you wind it out to 4500 rpm in one gear you need the torque to regain when you hit the next gear.The rpms may drop back down to 2500 when it shifts.This is where you need the most torque or it will struggle to regain.Also at crusing speeds no matter what transmission you have ,5speed or 700r4 your rpms are low.I see I have gotten away from the supercharger question.This would help and you could see gains as much as 110 ft.lbs more torque.This will totally change the issue of low speed velocity through the heads.It would not be relivent because the air fuel charge is now forced in.So there would not be a low rpm velocity issue.I am sure there are many manufactors of superchargers for your application.It would be the most bang for the bock but the cost of the setup could be as high as 1800 dollars .There could be otther hiddeng costs also like some kind of timming retard for full boost.Also some fuel upgrades.I am thinking Chevy may have run a concept truck like this at one time.