Stock injectors

[cor1]

I have installed a cold air intake and B N B high flow exhaust. I have the adjustable fuel pressure reg and want to paint a lot of the intake parts over the winter. it"s an 86 with 40k on it and runs well. I saw a MAF 4 inch sensor and was wondering if it was worth installing and enlarging the diameter for more flow. since I have the top off I was wondering why not replace the injectors now. 2nd thought was to increase the injector for more fuel since I have made the engine sbreath better on both ends. Are the performance chips worth it. Long story short, just lookiung for bolt on hp without engine work. That will come when this engine gets near its end.

 

[vetteoz]

No. MAF is not a restriction on stock engine On a TPI ,the intake itself is the major restriction;the runners are too small to make power at hi revs but give great bottom end torque. Making the MAF larger will do nothing for performance on a stock(ish ) engine


No .Bigger injectors will require a new tune .By all means fit new stock size injectors as your stock ones will be well worn
These new design Bosch type III highly recommended
Corvette, Camaro, Firebird, GTO Only - L98 CORVETTE, CAMARO, F'BIRD - 1986-1992 Corvette, Camaro Pontiac T/A Bosch Design III 22lb Fuel Injector - Fuel Injector Connection


and No
Off the shelf chips do little except lighten your wallet

Want bolt on performance increase; install long tube headers

 

[cor1]

OK, I have taken the restriction from the intake and will be putting on the headers and the B B exhaust. If i increase air flow then don't I need to increase fuel flow.

 

[cor1]

When u say intake do you mean the air cleanerr assy, or the throttle body and parts after that.

 

[cor1]

Do u recomend a set of headers, brand?

 

[Hib Halverson]

Your engine does not need "bigger" injectors nor a bigger MAF. Your current modifications, while they will improve flow somewhat, will not provide a great enough increase that you need to change injectors or a MAF. Adding headers may offer another slight reduction in exhaust restriction.

What you may need to do is change the ECM calibration, but that will depend on how the car drives, the air/fuel ratio at wide-open throttle and whether or not the engine can tolerate a more aggressive spark curve.

 

[92BlackVette]

Your wasting your time and money if you invest in anything but headers. Different injectors will probably yield you better gas mileage.

 

[vetteoz]

OK, I have taken the restriction from the intake .

You can't take the " retriction" from the intake; the INTAKE itself is the restriction to all out top end power. Intake change need

 

[cor1]

Recomended headers?

 

[cor1]

Am i correct to understand that the TPI is good to about 5k rpm and at that point the air flow restriction comes to play. I am not to worried about high end power with the stock block and heads. I believe the Valves will start floating around 55k and who knows about the bottom end. I ordered the B B exhaust L98 system from mid america, what would be a good header and connection parts for this system?

 

[Hib Halverson]

You are correct, the tuned port injection system was actually sized for a 5.0L engine then adapted for use on the 5.7. It is decidedly a low rpm induction system, however, it can be modified, at some expense I might add, for improved airflow.

The L98 lower end is "safe" to about the 350-375 hp level and 5800 rpm or so. Now, the OE valve train certainly won't run that high, but, if 350-hp is what you want, you're going to change a lot of those parts, anyway.

On an L98, with headers, low restriction cat and the B&B exhaust, you can look for a 10-15 hp improvement, provided the engine controls calibration is correct.

There are a variety of different header sets available for L98s. I'm sure others here will have some specific opinions on brands.

 

[surfer93]

You are correct, the tuned port injection system was actually sized for a 5.0L engine then adapted for use on the 5.7. It is decidedly a low rpm induction system, however, it can be modified, at some expense I might add, for improved airflow.

The L98 lower end is "safe" to about the 350-375 hp level and 5800 rpm or so. Now, the OE valve train certainly won't run that high, but, if 350-hp is what you want, you're going to change a lot of those parts, anyway.

On an L98, with headers, low restriction cat and the B&B exhaust, you can look for a 10-15 hp improvement, provided the engine controls calibration is correct.

There are a variety of different header sets available for L98s. I'm sure others here will have some specific opinions on brands.

I beg to differ with you, when I installed headers, hi-flow cats and custom exhaust, I gained over 35hp and I think 16-17 tq lbs on the dyno and yes the car was dyno'd on the same machine and was done right before and right after install.
When I ported the heads and intake, including runners, I gained about 14-15 hp and the torque stayed about the same, but the the car only pulled hard to around 4500 rpm's. Wish I had kept the dyno to show.
I put Hedman Elites on, because of the 1 5/8" primaries and they were in good shape when I sold the car about a year and a half later.
Also, it you don't like the drone, get a good resonator. My car would drive me NUTS at 55, I could not hear the radio or have a conversation without yelling.

Heck there is a guy on this forum(cant remember his id) who gained 8 hp just putting on the LT1 exhaust.