Hello all,

I am looking into upgrading my cam in the L98. The one I am looking at is advertised 283/287 duration and 495/502 lift with a LSA of 110. The part number is 22280 from summit racing. Can anyone advised as to weather I will need to reprogram the ECM and if so the best option for doing so. I called Summit but they were not able to give me a definitive answer.

 

Before thinking about tuning, just be aware that cam is too much for a stock L98 TPI manifold. The stock TPI manifold chokes off the engine well before a cam like that comes into it's main power band.

And even with a better manifold, the heads are also probably a limiting factor (though not to the same severity).

But aside from that, you'll definitely need tuning.

What year car?

 

1990. I have had the heads/intake ported and polished hoping to help the flow some. Another cam I am looking at is Jegs 746 PCE249.1011. Advertised 270/276 duration 495/502 lift with an LSA of 110. I was told by Jegs that I would not need to get stronger valve springs or reprogram the ECM. That is kind of why I am scratching my head. There doesn't seem to be a huge difference in the two cams.

 

Intake Duration at 050 inch Lift: 218
Exhaust Duration at 050 inch Lift: 224

1990 speed density system.

Yeah you'll need tuning for sure with either cam.

Speed density systems are typically far more sensitive to changes than the earlier Mass Air Flow systems. Maybe the Jegs guy had a MAF system in mind which might be able to get away with it.

They were running the ZZ4 engines with the Corvette heads with pretty aggressive ramp rates, so I would suspect the factory valve springs are ok.

This cam though is probably about the limit of what a stock TPI manifold can work with IMO... (especially if you also have a stock exhaust system too).

PM me... we can discuss further.

 

Running Muf/Cat deletes with H pipe. Short headers. On paper I like the more aggressive Summit cam but the Jegs will probably be more user friendly. I am on a fairly tight budget. The lower end is rebuild stock, no bore on the block, just a deep clean and hone. I'm upgrading to a double roller chain. My goal is to keep the low/mid torque profile of the motor with a slight increase to that torque and obviously a slightly more aggressive sound. I was getting ready to order the Summit cam and then realized I did not consider the ECM. Would a stage two chip work as a "reprogram". I do not have anyhow local that can reprogram the ECM and I do not want any issues during initial break in of the motor.

Tried to message. Says you've excided the message storage limit.

 

I agree with the others, that cam is way too big for tpi and for your heads. One way you could go is to sell the tpi and the old heads and get a Edelbrock pro flow manifold for Vortech heads. Then just grab a set of Vortech heads from your local salvage yard. That combo with that cam would make good power and wouldn't be extremely expensive.

 

Sorry...

Just cleared out some space on my inbox. Can try again.

These "stage II" type chips are often not really worth a whole lot IMO.

 

I think the 218°@.050 on the intake is probably about the limit as I was saying earlier. Could go with a ZZ4 cam (208/221 @.050 with similar lift). ZZ4 was making ~355 hp and 405 ftlb with a carb and dual plane. It'd be better suited to a stock TPI, but it'll sound stock and my guess is about ~325 hp with a stock TPI that doesn't breathe as well as the carb and dual plane.

If the OP is ok with not being optiimized for the TPI manifold while in pursuit of the "performance sound", then 218° @.050 is about the limit I'd go so as not to be disappointed in the performance (the exhaust system is at least tailored to it, but the TPI manifold will definitely be the restriction).

If there are plans for a high-flow type TPI manifold in the future then the 218 (or even the 220) cam would be probably ok. Though at that point I'd probably also increase injector size too... at least 24 lb/hr (if still running the stock-sized 22 lb ones... hopefully not still running the factory originals though... in which case I'd replace them now along with the new cam).

The only thing is, I'd probably go for a 112 LSA. The 110 LSA might be a little on the tight side IMO.

BTW, in my Miniram'd 383, I'm only running a Crower EFI 213°@.050 roller on a 114 LSA. With 1.6 rockers, probably ~215°. I really wanted the smoother idle which it delivered. But it seems to be more than capable of feeding the 383 and keeping up with the Miniram even up to 5500.

On a 350 with the TPI manifold it should do well too. Maybe could drop it to a 112 LSA for a little more rumpity idle. The smaller 350 will also make it a little more rumpity too.