I just bought two new T3's for my 350 i building up. Just wondering what cam to use on my L98 motor when using modified stock heads. I need to pick my cam soon so i can order new springs if they are needed for the heads. I plan on using this as a daily driver with nitrious and twin turbo boost with a superram intake. I am already burning my own chips so thats not a problem, only it needs to be emission legal. I was told my stock L98 cam would work great and save some money.

Any suggestions?

 

If you have the stock '91 L98 cam, then you probably are doing just fine. The big deal seems to be the lobe separation. It's important not to be shooting all your boost out of your exhaust which is exactly what happens when you have a lot of overlap. If memory serves, that stock L98 cam has either 117 or 117.5 degrees of lobe sep. which is pretty much ideal for a forced induction type application. I hope everything works out well. Good luck.

 

I would run a cam that is advertised for use with a boosted car, and try get as much lift out of those stock heads as possible. I think max lift is at .475 or something with 1.5's and the stock iron L98 heads. Be sure to match the cam to the rest of your combo (or vice versa). You dont want a setup that conflicts. I'm running a boosted TPI (stock heads/cam/intake) and I think the stock setup is a horrible combo for fully utilizing boost. Yeah it makes alot of torque but the powerband ends too early. I think with just the right intake and cam change in a boosted L98 setup you'll make a noticable increase in HP. Thats what I'm doing with my blown 91Z28 right now. Converting to HSR and installing a blower cam. If you wanted to stick with TPI then you would want a cam for a lower powerband, probably be a torque monster. If you're auto you wanna make sure it'll match the stall. Stuff like that. Just be sure to match it up. Tech support line at the major cam places should be able to help.

 

Even with a larger cam you'd be surprised at what will pass a sniffer test if you retain cats and emission equipment. I have a 218/224 114 lsa and had no issues with emissions before I started adding other mods (that was back when I lived in Houston)

 

You’re still talking about baby cams there… there are a few people floating around that have gotten cams in the 23x/24x/112 range through emissions…

 

High Duration, high lift, close (not too close) lobe separation.

 

i got a 235/235 on 114 LSA carb in a 350 to pass emissions for a LG4...just for reference

 

Actually, with a turbo it’s forcing exhaust into the chamber or even into the intake, on a turbocharged engine you can pretty much rely on having more pressure at the exhaust valve then at the intake valve.

There’s been a lot of mention of stock L98 heads and lifts in the .475-.480” range… Is this the actual max lift or is this what people consider a “safe” max lift (probably with .050” clearance before the keeper/retainer assembly contacts the valve guide/valve stem seal?

 

I'm not sure if it is true max or just safe. I asked the Comp Cams phone guy what the max was for my iron L98 heads and thats what he told me (.475), but who knows right? He could have just been giving the safe recommendations. To be honest I dont have enough experience with it to say I know for sure.