Still trying to figure outwhat I want to do.

I've got some Vortec heads that I hope will work pretty well. I know what all that entails, they're already clearanced for lift (Though it's a shame I doubt I'll even approach a need for it given my application).

I just want a quick street car. I've got a 350 in the works, and I'm thinking I will just carb it in the meantime and save up some money to get the whole enchilada TBI system I want with Rbob's EBL and get a laptop, etc etc.

So here's my question.

THe cams I've been looking at are the Comp XE256 and the Comp XE262. The 256 has a 112 LSA and it's cheaper than the XFI 114 version, so I figure 112 should suffice, no big deal. Perhaps I'm wrong, but I assume it will.

The XE262 apparently doesnt come in anything but 110 and 114 LSA. So I can save $20 and get the 110, get the cooler idle sound, and according to summit's site, a wider powerband.

On a side note, the XE262 kit with the 114 LSA costs the same as the one with the 110 LSA, yet individually the 114 is $20 more (I think). Kind of silly, but I suppose cam manufacturers are the biggest scam artists around given that bigger cams most likely do not cost that much more to make than small ones. But that's another thread for another day.

Back to the subject... I do not know how to tune a computer, or a carb really, but I think I can learn. I'm pretty resourceful, pretty smart, and I learn quickly. But is trying to tune a 218/224 cam with 110 LSA just going to be too much to deal with? I know it treads close, but I dont know how close.

ALso, if you guys have any other cams in that neighborhood you think I should check out, let me know. But I'm thinking if that 110 LSA version if it really has a wider powerband (I assume the numbers on the websites are just crapshoot approximations) then it would make it all that much easier to deal with the stock torque converter. I'd rather be able to make the stock one work until my tranny cries uncle (Which wont be long, probably, but it's not smething I want to pay for now) and just deal with that when the time comes.

Besides, a wider power band is good for everyone, although Im aware it's probably a subtle difference.

 

LSA really makes a subtle difference in power band, you are probably talking about 10 hp peak vs a wider power band. I've always read and under stood that a narrow LSA makes for a peakier power band and helps peak power. A wider LSA makes for a wider power band but gives up peak power. Might want to double check you sources on the tech you got. The way I understood it the narrower LSA helped with scavanging because the intake and exhuast valves were both open together longer, the only down side is that scavanging only works in a narrow power band, hence the peakier HP curve.

Where LSA will hurt you is in idle quality, the increased overlap give you a lumpy idle....which in turn gives you a lumpy map reading. As long as you are aware of this and aren't expecting a glass smooth idle at 14.7 to 1 AFR you can easily tune around much a much bigger cam than you want to run. I ran an extreme energy 26X somthin 4x4 cam with 218/226 dur. and a 110 lobe sep. It had a noticable idle and would bonce around about 10-15 KPA, I just flatended out my timing and VE curves in this area and this helped trmendously. I also started running open loop (no O2 sensor) and aimed for about 13.5 afr at idle and this also really helped to smooth out the idle and get rid of the acrid exhaust smell. Bigger cams just don't like to idle at 14.7 that the stock ECM shoots for.

If you trully want to run TBI, I wouldn't go through the hassle and expense of running a carb. I would spend the dough on the burning equpment now and learn on your stock motor while you finish the 350. Just getting started and learning how the system works is half the battle. You could then swap to the EBL system, learn it and then do the 350 swap. Baby steps are always best, I learned to tune on the cam I mentioned and it was tough. If I would have started on a stock motor and then swaped to the mean one it would have been much easier.

 

deffinately a 114 lsa will have a wider power band than a 110 lsa. 100% sure of that is I.

 

xe262 with 110 LSA http://store.summitracing.com/partde...2&autoview=sku

Basic Operating RPM Range: 1,300-5,600 RPM



With 114 LSA
http://store.summitracing.com/partde...4&autoview=sku

Basic Operating RPM Range: 1,500-5,500 RPM


It seems counterintuitive to me too, not really sure why a cam that runs rougher at low speeds would have more power down low than one that runs smoothly there...