I was wondering if anyone here had there heads ported and polished and if it had any decent gains, since my motor is screwed I figure I can port the heads I put on it when I finally get motor.

 

I keep trying, but the wife is strictly opposed to road head.

 

http://forums.maxima.org/showthread.php?threadid=72447

 

Do you have it done or just heard it doesnt have any gains.

 

Just a port and polish by a DIY... perhaps its not worth it.

I have talked to Dan Parmore Racing (DPR) about this. They claim to have dome one set of Maxima heads. Dan said theyr was room for improvment. I dont know who the heads belonged to. It wasnt Mathel, so I think its a particullar Texan who is understandably secrative about forking out big bucks for performance mods.

If you send the heads to a reputible performance machine shop like DPR, they "clam" that for $2500 they can get you a 15-20% gain in power. They will do allot more than port and polish. As an example...

Flow bench with port and polish
Unshroud the valves
High flow valve job
Weld and reshape the combustion chamber
Coat the combustion chamber and valves with heat disapating ceramics
Port match the in/out ports with manifolds.

I think 10-15% is more resonable...
For a boosted car making 275fwhp they could be worth 27.5-41.25fwhp.
Dollar per horse power thats very expensive, even at the best case of 15% you are paying $60.60 per FWHP. A V2 SC at $4000.00 makes ~65fwhp on the stock pulley for $61.53 per hp. A CAI or Y pipe is about $30 per hp.

If you have the money to get it done professionally then do it.

FWIW Just getting the combustion chamber and valves coated is not too expensive and will yield some power on a boosted car.

IHMO of course...

 

I would just get my head polished. Very short term gains and then tired.

 

I intend to get this done when I have my engine apart and out of the car....hehe

-Mike

 

Tilly's what happened to your motor??

 

thanks MardiGrasMax Im planning on going boosted and I have a friend who has a bench flow thingy and will do them fairly cheap. For those of you who want to know what happened go here


Window switch a must for NOS on an automatic

 

ouch thats what i am afraid of when going the NOS route on my 97

 

i got my heads port/polished when i had the motor built, They were tested on the flowbench for cfm also. I chose not to get 5 angle valvejob due to the drawbacks that are associated with them.

 

Can you elaborate please Mathel? Is it a wear issue?

 

ouch. Sorry to see that.

SuDZ

 

Yes, I'd also like to know why the 5 angle valve job isn't a good idea. I was plannin to do that too.

Also,

Matt-
I'm thinkin of runnin NOS too, know where I could get the wet setup done to my intake manifold while its off the car?

Thanks

-Mike

 

I would talk to Tony "1MAX2NV" about the profogger plumbing. His shop did a nice job.

 

5 angle valve job is not necessary the best for street use cause of possible excessive carbon buildup. The more angles has more places and tendancy for carbon to buildup. Too much carbon buildup and you can get low compression and other probs. Im sure there are more technical ways to explain this but this is in my own words....
im not sure but i think the Maxima stock already is a 3 angle valve job.

 

From my understanding, it also increases wear as the valve seat now has a smaller area to contact when closing each time. so less area to accept the pounding = accerlated wear on the seat.

 

Woooooah, you been talking to the bean counters?

 

It all comes down to beans, dosent it Chief!

 

What if I planned to build my maxima for road racing, i.e. Lime Rock Park, Watkins Glen, Laguna Seca, etc......Would the 5 angle valve job be better for that setup, or do you still recommend going with the 3 angle valve job?

-Mike

 

http://www.sa-motorsports.com/diyport.htm

This is a good link for the basics on this subject.

 

I think Im going to do it myself since I have all the tools needed Ive already done a set on my VW and it made a big difference till the waterpump took a **** and cracked the head due to overheating. I have 2 sets of heads to play with so screw it.

 

Small world, I have a 16V Scicocco I did the heads on also!

The key with out a flow bench is to only do minor shaping. Cause if you hog it out too much you will loose some usable power.