I recently blew my 409 stroker motor in my Impala SS.

I have a good engine guy to build me another no BS strip motor (LT1).

My builder wants me to ditch my current LT4 heads and move onto his AFR's.

But i need to know how much better they are if im shelling out 2-3K more for a stroker build.

 

Dunno about for a strip motor, but if you get the LT4 heads fully race ported they will bet as good as any other head out there. For the hp gain it's not worth it IMHO. Why not just go to forced induction for a similar wad of cash and get way more power...

 

here is a pretty good site for comparo's.
Flow Numbers for LT1/4

 

No im not running NA. This will be a Nitrous motor with 100hp 1st stage then a 250 direct port 2nd stage.

 

I'd go w/ some big AFRs on any stroker motor. The thick deck on the AFRs is also gonna be better w/ the power adder.

 

The thick deck notwithstanding, the LT4's can be ported to flow just as well as a comparable AFR LT4 casting.

 

TTT give me the info i crave!

 

Rise post RISE!

 

Don't do it, if you really want to spend that cash spend on getting them ported, but they don't certainly dont suck. Its the same as switching Filet Mignon for Prime Rib, they are both equally good.

 

You have to define which AFR heads you are talking about as they make 3 port sizes for the LT !.

 

My engine guy said that is i go with LT1 AFR's the 227 casting he can get close to 330 CFMs with a 2.08 intake valve and 1.60 exhaust.

 

Agree. But in general, the AFR castings have more potential. If you already have a set of good LT4 heads, it may not be worth the money. Depends what your priorities are and how deep your pocket is. Since it's a nitrous motor, I'd say just add more juice!

Rich Krause

 

Rich is right on both accounts (IMO).

The AFR's definitely have more potential than the GM lt4 casting, but for a n2o setup it may not be worth the added expense

 

Well once i remove my Ported and polished stage 3 LT4 heads they ought to be worth at least 800-1000 dollars and should sell easily.


And the bare AFR 227's are only 1100.00 Plus port work and springs retainers liftrs pushrods ect..

But I was already planing on going to a solid roller so most of thoose parts would have to be purchased any ways.

 

Havent seen an LT4 head ported that flowed over 300 cfm yet.

The AFRs are some really nice peices and respond very very well to porting. If you shop around you can get them for under 2 grand complete, and if youre the industrious type (like myself) you can have less than 1500 in a home ported set that flows better than LT4s. I bought mine from www.strokermotor.com

The AFRs flowed as advertised out of the box, but with some mild clean-up and hand porting by me, they gained about 8% more flow. Here is a site that goes into detail on the simple mods todo to AFRs www.ws6transam.org/afrheads.htm I did these mods and a few others (basicly cleanup) to mine and the improvement was astounding.