Any real gain upgrading HEADS

[turbo89]

It really doesnt take much port work to see big gains with the stock heads. When you pull the valves you will see how crappy and restrictive they are under the seats. A quick clean up on that and a taper on the guide opens up a lot. I have a set of iron heads thag went 9.8s that arent anything special.

I totally 100% agree ... I was amazed at how well a set of self ported heads did ... I maybe spent 10 hours total on them ...

but what I did is look at what other head porters did .. and then sat down with the porter I use now and asked ... WHY is this being done ?
I am lucky as we trade info back and forth .. he is familiar with NA power while I deal with Turbo power .. in short he does not port heads the same way for both applications ..

I simply am amazed at how well a set of stock heads that are just mildly done can perform ..

For the typical 10.50 car I cant see spending $2K on alum heads .. its a total waste of money

 

[TurboTnZ06]

Just bowl port your irons, stock sized valves, throw a cam in it to get power to 5500. Stock at 17-18 psi I went 13.0's at 104, 17-18 psi with 210/210 on 110 lsa roller cam and bowl ported irons and same everything else, went 11.8's at 115. Same heads more turbo and more boost = 10's at 127.

 

[delcowizzid]

We just did ported heads on our 89 ln3 engine were a set of hand ported heads by my guy who knows the tricks and where to work no flow bench used 5 angle seats slightly larger valves and mostly bowl work no real upsizing of the port ..went from 10.50s@127mph on 23psi to 10.30s @130.9 on 18psi waiting for new injectors and pump to get it back upto 23psi for a 9 second pass was definately a worth while bolt on mod.drag calculator said over 50rwhp more than the old runs at 23psi on 5psi less boost so at 23psi it' going to be well over 100hp at the tyre gain for 1 bolt on mod lol

 

[earlbrown]

You can get over 80% of the gains by doing a couple fairly inexpensive things to stock heads.

The cheapest is to pull them apart, do a bowl port and a fresh 3 angle valve job. If you actually look at a stock port and then one that's bowl ported, you'll wonder how these cars ran in the first place. Then back cut the stock exhaust valves to get rid of the ski jump.

If your budget allows, get a new set of Ferrea valves with an OS intake. That will give you fresh meat for the valve job in case the seats are beat the hell. The exhaust is the same size as stock so if the seats are beat, you'll need hardened seats. If the exhausts get changed out to aftermarket, you can install positive seals on the exhaust guides. You can't do that with a stock exhaust valve. I'd be a waste of money because the seal will get smoked.

After all that's done and the valves are tipped to the same height have them resurfaced. ....and NOT by a belt sander!

 

[gusszgs]

to answer your question with specifics .. Same car .. same shortblock ... just a head swap to the ported iron Champs ...

The tune was maximized in both configurations and weather was more favorable to the stock heads vs the champs ...

11.62 @ 115 on the stock heads
11.19 @ 119 on the champs

This was on a HEAVY , Fully loaded Limited .. had this been on a stock weight GN .. probably would have been in the 10.90 area ...

The turbo was simply out of lung .. same setup with a larger turbo went 10.56 @ 128

Wow , was this with a stock cam?

 

[turbo89]

Wow , was this with a stock cam?

junk hyd comp 206 on both .. cam wasn't ever changed just the heads