How much HP with head work?

Hey all;
I'm just wondering... when I get all this head work done, about how much HP am I going to be getting from it? I'm going to get the head ported (not oversized), port-matched runners IM and header, 60mm TB, port-match IM again, stock valves, probably alittle better springs and retainers, adjustable cam gears, and some basic cams. I'm not talking stage 4 cams where they cost like $1000 for one of them... just something alittle over the stock ones. What kinda power am I looking at on just the head alone? Like 20hp? I know with the intake and exhaust it'll get the full power of it. Let me know. Just a rough estimate. Thanks. Compression is going to stay the same.

Very hard to answer such a question. Depends on how good the person is whom is doing the job, how restrictive the head is in the first place, and how good the person is whom is doing the job. If you aren't changing runner, or valve size, not as much. That is OK though bigger runners aren't always a good thing. I think if the head was all you did you MIGHT see 15 or 20 IDK I'm just guessing. It sounds like you have a good plan, and you should see some nice gains. Are you going to the dyno after everything is done? I think it is interesting to hear about someone taking a non fast car and making it fast.

Good luck!!!:D

Yeah. It's going to be awhile before everything falls into place. This is where it gets expensive, and I'm kinda broke. But, it looks like I won't be dropping the car this summer and spending all that money on the head.

I know there's really no way to tell... I was just looking for a ballpark figure. Should I change the valve size? Would it be worth that extra money? I'm going to get the head ported somewhere else (not sure where yet) and I may be willing to spend that extra money depending on the gains we're looking at.

Something else I didn't realize too is that this head job will chnage the sound of the car alot. With cams and larger everything, it should sound like a beast.

Any ideas are very welcome here. Thanks.

I agree with loeman, with just the head work I think you would see about 15-20 but I think the total will be closer to 30. Just depends really. I'd love to see a dyno sheet of the difference when you are done.

Should I change the valve size? Would it be worth that extra money?

I think you should contact the cam manufacturer, they can usually make some good recommendations. Everything has to work together effeciently, and you need to have a certain RPM range in mind. IMO if you don't increase runner size, and use a mild cam, then bigger valves aren't going to increase airflow that much (might even lose velocity). Definitely call the maker of the cams though, the bigger brand name cams have specialists who make recommendations. Remember, racers never buy a part just once though, and you may not be happy with the first combo you put together. Be ready to experiment with cams, and valves, and runner sizes. Keep up the good work, and keep us posted. :D.

See the thing is... head work is expensive!! I don't have the money to experiment with different setups. I would just have different cars then. Remember, this car is a daily driver. I can't have any down time. That's why I bought another head, and building it on the side... then going to do a swap.

On the other hand, I found a place to port starting at $450.
http://catalog.exileracing.com/product_info.php?cPath=215_248_223&products_id=425&osCsid=488ca997a728803a52c7d9264a4dc465
Is that going to be one of the best? Can a local machine shop do something like that, or is it best to have an automotive place do it. I think the second is the right answer. As you can see in the link, it can get very expensive when I start adding the parts from them too. Just the basics, I'm already looking at $1000. I don't have that kind of money. :-(

I don't know what cams I'm going to be using yet. I want something not too expensive, but yet will still get some power. I know cams make a huge difference in sound too, and I want a nice low rumble. lol. Not that important though. I don't know what to get.

I tried taking out some of the valves and guides and springs using bootlegged tools. I got 1!! Still got some work to do to clean it all up, so it gives me time to look up stuff.

Not to be an ass, but if you put that kind of money and work into a turbo dsm head you'd be looking at 50+hp.

And there it was...

I was waiting for that. Totally missing my point here. Non turbo only.

And there it was...

I was waiting for that. Totally missing my point here. Non turbo only.
Sorry couldn't help myself. :licka:

david-b Im not try to be mean or something, Im down with ez1286 just say, sell your car or save up money for turbo dsm ( like me :wink: ).

Can we not turn this thread into a NA/turbo fight. I've been on this forum for a long time now... longer than alot of people here. You guys know what I'm doing. I'm not turbo-ing the car, or selling it and buying one. That's final.

david-b Im not try to be mean or something, Im down with ez1286 just say, sell your car or save up money for turbo dsm ( like me :wink: ).

No way. I like what he's doing. Not many people go this far with the 420A, and I'm interested to see just what he can do with it staying N/T. I also want to see a dyno sheet once all is said and done. I will never go this far, but since you have as much money as you do invested in the car already you might as well keep going and make it the best you can.

I forget your goal was 210whp. Keep your head up and chin down J/K. Im never own a turbo car, so Im still consider a n/t guy. good luck

See the thing is... head work is expensive!! I don't have the money to experiment with different setups. I would just have different cars then. Remember, this car is a daily driver. I can't have any down time. That's why I bought another head, and building it on the side... then going to do a swap.

On the other hand, I found a place to port starting at $450.
http://catalog.exileracing.com/product_info.php?cPath=215_248_223&products_id=425&osCsid=488ca997a728803a52c7d9264a4dc465
Is that going to be one of the best? Can a local machine shop do something like that, or is it best to have an automotive place do it. I think the second is the right answer. As you can see in the link, it can get very expensive when I start adding the parts from them too. Just the basics, I'm already looking at $1000. I don't have that kind of money. :-(

I don't know what cams I'm going to be using yet. I want something not too expensive, but yet will still get some power. I know cams make a huge difference in sound too, and I want a nice low rumble. lol. Not that important though. I don't know what to get.

I tried taking out some of the valves and guides and springs using bootlegged tools. I got 1!! Still got some work to do to clean it all up, so it gives me time to look up stuff.
The "street" port on that site is something you could do yourself, or have a local speed shop do IMO. All they do is gasket match, 3 angle valve job, and polish the chambers. Then again if you don't trust any of your local shops, the online option is all that is left. When I said be ready to experiment, I didn't mean dump a butt-load of money in all at once ;) . I mean if you are going to keep the car, then later down the road you might think about changes.

Cam selection is all about RPM range. Take into consideration the weight of the car, manual tranny, etc. Since it is your daily driver you will want to keep the duration fairly short, but you can get away with a little more because you are MT :). You will want a broad power range for the street, so you have good torque available at any RPM point.


As for the rest of you :p I would like to see him continue with the N/A project. ALMOST makes me want to go get a GS and make a drag car out of it. :smooch:

What exactly is a "3-angle valve job"? or a 5?

Exactly what it sounds like. The valve seat is ground at either 3 or 5 angles. The more angles, the smoother the airflow will be entering or exiting the combustion chamber (air doesn't like to turn corners), and it will also make the part of the seat that touches the valve thinner (which has the effect of opening and closing the valve faster, and reducing friction on the head of the valve). The more angles, the better. A competent shop BETTER be able to do a three angle, a five angle job is not as common, and most of the older domestic heads I see have a two angle job from the factory. Some shops will also be able to undercut the head of the valve, but I wouldn't recommend it on your stock valves.

I'm going to contact some shops that are close by and see what they can do. It sounds like I for sure want the 3 angle then. 5 will probably cost way too much. There's not too many shops like that around here that do, well, anything. All they do is order parts online. Wow. There's some shops up north from me that I'm going to have to call and see what they offer.


Thanks to everyone that's behind me on the whole N/A thing. I may be dynoing my car in the next couple weeks to see where I'm at right now.