I am in the process of planning a buildup of a 327. I am going to continue using the TBI on it. I have all the equipment to burn a new chip for it. Here is the plans for the 327 so far.
*XE268H cam
*Edelbrock Performer Air-Gap.. or other performer intake.
*Ported/slightly decked L98 heads with stainless steel valves and
springs to accept around .500 lift...not sure.

Question....
1) What size injectors should I go with? I am going to make the
FPR adjustable, but I am thinking that going with 350 injectors
would help out a lot.
2) How much tuning is this going to require? I know it would bea
ton easier to go with carb, but I would like to give this a shot
first.
3) What are the differences between the L98 heads and
Vortecs? I know the guy that did the work on them, and he
says that they will flow comparably to the Vortecs.
4) Will the stock TBI size be able to handle the amount of air
needed? There is always the 454 TBI or that Holley TBI. I will probably be able to get away with the stock one.

I can't think of any more questions at the moment. Please let me know if I am forgeting anything. Will this combo work very well? I ran it on Desktop Dyno 2000 and it gave 380hp and about 380torque @5500 I'm not saying that is what I will get however.

Thanks for any help anyone can give me.

Tyler

 

I can answer a couple questions....

1) Use the 350 injectors.
3) The Vortecs have a new raised runner intake design that virtually eliminates the need for pushrod clearances; the L98's use the dated pushrod runners which 'chokes' incoming air/fuel in higher performance applications. The L98's combustion chamber is a simple half moon with a low quench intake charge and a spark plug aimed in the general direction of the exhaust valve. The Vortec uses a kidney bean shaped chamber (borrowed from the LT1) and has the spark plug placed very close to the middle of the chamber; the exhaust valve is also quite a bit more unshrouded than the L98's, and intake charge gains a higher quench characteristic.
4) The stock TBI unit flows 520cfm. You can use the VE equation to figure out how much air you actually need....

ci x max rpm / 3456 = *** @ 100% VE

Example: 327 x 6300rpm / 3456 = 596cfm @ 100% VE
Take note though that a street/strip car would only be able to hit about 95% VE so it would only need 566cfm. Something to think about.

 

Ok, well 327 x 5500RPM / 3456 = 520 cfm

So I would imagine that with the ultimate mods/350 injectors, I will be all set for the fuel section of this.

AS for the heads... I don't really mind that they are different. Since they are that different, do you know what the power differences would be between the two? I think I can get these heads for about $400-$500 instead of the $500 for new vortecs as well as another $100 for springs, and $100 for the rocker arms. Plus, while I'm at it I would do some machining as well.. So, I can get Vortecs for about $750 or the L98 heads for $300 less. I am trying to build this engine as cheap as possible. Will there be a 50hp difference, or will it be something more like 10 or so?

Thanks for the help. So far at this point, I think I am going to go with the L98's just because I don't have a lot of money for this and I have a bunch of other stuff to do to the car. Tranny needs some work. 150k miles wont last too long with a built 327 in front of it.

 

Dyno tests show 35hp and 20ft-lbs of torque difference in a out of the box comparison.

 

Well, that doesn't seem too bad. I think since the L98's are ported and everything, their shortcomings compared to the stock vortecs will be made up for a little. Thanks for the help though. I was just checking into the differences between the two.

 

Yeah it really isn't a huge difference. If you're going to make a lot more power you might as well go to a true aftermarket head anyway.

 

I don't have a lot of money, so I am just going to og with the L98 heads. Their shortcoming will buy me some other stuff like shifter, and put a little towards the tranny.

Thanks again for the help.
Next project is home-made wonderbar, LCA relocation brackets, as well as boxing LCAs

Thanks for the help. As soon as I can get those heads, I am going to get started on building the engine.