Hypertech or jet chip

[Paddywhack]

During my recent rebuild, I shot Brian at TBICHIPs an email with all the modifications I was doing and they burnt me a Stage2 chip. Even answered the phone when I called and stayed on the line and helped with a small technical question. All for under 150 bucks. Havent pushed the engine yet, (damn snow) but it starts fine, and ran great going around the neighborhood a couple of times. Well worth it in my opinion!

 

[Rogue]

Hypertech charges $179-$230 for the generic chip.

 

[Rogue]

So whats a guy to do to improve performance?

The L98 TPI has been around long enough so that it's almost a science to get the additional power you would like. The added power comes in stages of modifications and they are a proven formula that is repeatable.

Basically if you have the TPI then you free up the intake and exhaust, then tie it altogether with a custom chip so your ECM can take advantage of the greater intake and exhaust flow.

Intake:
Open top air filter box
Airfoil on the Throttle Body

Exhaust:
Freer flowing cat back exhaust

Fuel:
Adjustable Fuel Pressure Regulator

A custom chip to takes into account all the above will easily net you about 30 bhp. You can adjust fuel pressure using the chip programming.

If you have more $$, then:

Intake:
All the above plus-
Big mouth lower plenum
Big Tube TPI Runner
Larger throttle Body

Exhaust:
All the above plus-
Long Tube headers
Freer flowing Catalytic Converter

Fuel:
All the above

Engine:
Depending on year- AFR aluminum cylinder heads
TPIS camshaft (forget which grind--the milder one to pass emissions)
New Timing chain

Finally, that custom chip to tie it all together. I have seen actual magazine reviews who performed this mod on their C4's get 100 bhp from this. That's significant for an L98 TPI. And if you tune it right and you take it to an "understanding" Emissions Tester, it will still pass.

Or......

Slap a ZZ4 (383) and never look back. You can still do all the above on a ZZ4 motor to get the maximum power from that motor.

 

[vetteoz]

The L98 TPI has been around long enough so that it's almost a science ..................

The first , best bang for $$ mod on a L98 is long tubes followed by a free flow cat
The L98 is well known for it's exhaust deficiencies

 

[vetteboy86]

After the Long tubes go on, changing plugs is a snap!!

 

[bucket]

This is only my opinion based on what I have read from various publications who have run articles on how to make the C4's run faster. Engine temperatures were mentioned often.

From what I gather, the L98's run the fastest at around 180 degrees. Unfortunately, it is not as efficient. It is most efficient at 190-200. That is where the oil temperature can do its best at protecting the engine. In addition, it produces the best emissions results at 220. Most watercooled engines produces its best emissions around 220 especially at idle where the beginning of the emissions test phase is. This is one of the reasons manufacturers allow the cooling system to cool an idling engine around 220 to get the best emissions result possible.

Having said that, I think if you are a drag racer and want the maximum possible power from your C4, you would want a 180 degree thermostat and a chip to work with that to keep your engine from going above 200 degrees. If you must pass emissions testing bi-annually, you may want to keep the stock thermostat and stock thermostat cooling temperature.

I do believe that using anything lower than a 180 degree thermostat is hurting your engine since it won't allow oil temperature to get to its proper working temp especially during the cold months.

.

i put in a 160 hpertech stat and an adjustable fan thermostat.
with the AC off(to keep the fans from running) i can regulate my operating temp from 174 up to and aver 207

 

[bucket]

btw: it makes a Noticable difference in throttle response running @174 as opposed to 207

 

[J Brennan]

Glad to see someone finally spoke of the 160 stat.. You will have great throddle responce that can be made even better by taking the hot water hose out (bypass). Not recommended if you drive in cold weather. I have the entire Hyper. package With termo chip. Emmissions are low, oil & bottle of Z Max changed every year (1000/1500) miles a year. Used oil looks great. Yes chevy designed c-4s to run warm for all year all state weather conditions but most of us are summer car cruisers ( calm down southern boys) and for that these mods do quite well

 

[nelson84]

The first , best bang for $$ mod on a L98 is long tubes followed by a free flow cat
The L98 is well known for it's exhaust deficiencies

Actually it is not the best bang for your buck. According to "Corvette Fever May 1999" The article on project x-s an exhausting subject. After installing long tube headers on an 85 corvette they found an increase of a maximum of 6.3 hp at 4200 rpm and an average of 2 hp between 1900 rpm - 5400 rpm. And 10.2 lb/ft of torque at 4200 rpm and an average of 4 lb/ft of torque.

Don't bother with expensive long tube headers unless you get new heads and a cam and intake.

 

[J Brennan]

Yes headers give much more free flow. Factory exhaust manifold doesn't flow nearly as well. Machined heads will allow headers to do what they were intended for