Head work Opinions - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


General Miata Chat A place to talk about anything Miata

Reply
 
 
 
LinkBack Thread Tools
Old 06-07-2008, 04:34 PM   #1
Elite Member
Thread Starter
iTrader: (8)
 
Join Date: Oct 2007
Location: Dallas
Posts: 1,841
Total Cats: 0
Default Head work Opinions

The site has been over this and over this. Everyone has there own opinion.
But here it goes.

For 12 psi in a miata, You need do nothing extra. But for more horsepower some say port heads etc. etc.

This head shop said "let the turbo do all the work". Well we know that.
He was so stupid he couldn't hear me out.

Anyway, I may just run boost on stock for a while. Begi said 12 psi will give good power and dependability.
So i will run 12psi. But if I ported the heads and had valve angles. Wouldn't it flow more efficiently. More air for the same psi???

Or will it not make much differance? He said he would just have the valve angles done, That should give 15 hp on turbo. The 3 angle job is $135.00

At what psi will head work be worthy.
What do you think?

And yes, I will deffinatly be checking more head shops for there opinions.
Toddcod is offline   Reply With Quote
Old 06-07-2008, 04:48 PM   #2
Elite Member
iTrader: (24)
 
kotomile's Avatar
 
Join Date: Oct 2006
Location: Monterey, CA
Posts: 7,578
Total Cats: 40
Default

On top of the gains in flow, headwork helps with spool. Worth it, IMO.
kotomile is offline   Reply With Quote
Old 06-07-2008, 04:58 PM   #3
Elite Member
iTrader: (5)
 
Atlanta93LE's Avatar
 
Join Date: Sep 2006
Location: Marietta, GA
Posts: 2,198
Total Cats: 1
Default

Read this Autospeed article on the topic. Interesting.
Atlanta93LE is offline   Reply With Quote
Old 06-07-2008, 05:17 PM   #4
Elite Member
iTrader: (7)
 
samnavy's Avatar
 
Join Date: Apr 2006
Location: VIRGINIA BEACH, VA
Posts: 6,020
Total Cats: 175
Default

^That is an interesting article... but all his talking points are based around a naturally aspirated engine, always in vaccum. I think the article would read differently if he'd started with the premise of boost.

In any case, the $130 price quote can't include teardown and reassembly of the head. If you have him strip and reassemble the head, the price goes up dramatically... so you might want to do some homework into what it takes to do that. If he's going to do any work at all, you might as well have him do more than just the valve-angles.

But to a certain degree, I hear what your mechanic is saying. Guys have no trouble making 250whp at 12-13psi with the right turbo on this car. If you had your setup listed in your sig I would make helpful comments, but as it stands, the Begi S4 manifold and a GT2560 w/3"exhaust sounds like a good place to start before headwork if the motor is currently solid. When you blow it, then rebuild it right.
samnavy is offline   Reply With Quote
Old 06-07-2008, 05:22 PM   #5
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,114
Total Cats: 351
Default

you need to talk to John Day in Richardson. He's made tons and tons of FI miata motors, and from the reaction of people on this forum, dirt cheap.
hustler is offline   Reply With Quote
Old 06-07-2008, 05:48 PM   #6
Elite Member
iTrader: (5)
 
Atlanta93LE's Avatar
 
Join Date: Sep 2006
Location: Marietta, GA
Posts: 2,198
Total Cats: 1
Default

Quote:
Originally Posted by samnavy View Post
^That is an interesting article... but all his talking points are based around a naturally aspirated engine, always in vaccum. I think the article would read differently if he'd started with the premise of boost.
True, true.
Atlanta93LE is offline   Reply With Quote
Old 06-07-2008, 06:01 PM   #7
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,353
Total Cats: 1,319
Default

If you have the head off, there's no reason to not do a little headwork.
Savington is offline   Reply With Quote
Old 06-07-2008, 07:12 PM   #8
Boost Pope
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Chicago (Over two miles from Wrigley Field. Fuck the Cubs. Fuck them in their smarmy goat-hole.)
Posts: 26,315
Total Cats: 1,913
Default

First off, I would not do a multi-angle valve job on a turbo car. Cutting the seats in this way reduces the total surface-area of the contact patch between the valve and the head when closed, which in theory will decrease the cooling of the valve through the seat and into the head.

As to headwork in general such as polishing, port-matching, etc., it's a fairly basic tenet that for any given manifold pressure, a properly worked-over head will produce more power than a stock head.

In a naturally-aspirated car, you have a definite upper-limit on the manifold pressure that you can achieve, namely atmospheric. Thus, headwork is one way to overcome this limitation.

In a turbo car, assuming you have some margin for dealing with the extra heat, it's much cheaper and easier to just turn up the boost. Yes, a well ported head will make more power at 12 PSI than a stock head, but why bother when you can get essentially the same result by twisting the **** to 13 PSI?
Joe Perez is offline   Reply With Quote
Old 06-07-2008, 07:40 PM   #9
Elite Member
Thread Starter
iTrader: (8)
 
Join Date: Oct 2007
Location: Dallas
Posts: 1,841
Total Cats: 0
Default

Ta DA! here is my setup.
Where is that guy in richardson?
Toddcod is offline   Reply With Quote
Old 06-08-2008, 08:39 PM   #10
Elite Member
 
Join Date: Jul 2005
Posts: 6,454
Total Cats: 80
Default

Turbo motors respond the same to headwork as NA motors do.
JasonC SBB is offline   Reply With Quote
Old 06-09-2008, 06:54 PM   #11
Elite Member
iTrader: (21)
 
paul's Avatar
 
Join Date: Jun 2006
Location: Point Pleasant, NJ
Posts: 2,957
Total Cats: 2
Default

if you have a 94-97 just pick up a 99/00 head/intake
paul is offline   Reply With Quote
Old 06-09-2008, 09:48 PM   #12
Senior Member
 
Join Date: Sep 2007
Location: Alamo City, Tejas
Posts: 774
Total Cats: 1
Default

Quote:
Originally Posted by paul View Post
if you have a 94-97 just pick up a 99/00 head/intake
...and then get the headwork done...

- L
l_bader is offline   Reply With Quote
Old 06-09-2008, 10:35 PM   #13
Guest
iTrader: (6)
 
Join Date: Sep 2007
Location: Vaughan, On, Canada
Posts: 1,092
Total Cats: 0
Default

It is funny... I never found a big difference in power between my 94-97 head or the 99 head I used on my old 500+ horsepower Miata. Both were stock and would create the same HP within 1-2hp. (Which could be just due to different days etc)
M-Tuned is offline   Reply With Quote
Old 06-11-2008, 12:26 AM   #14
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,353
Total Cats: 1,319
Default

Quote:
Originally Posted by mkulak View Post
It is funny... I never found a big difference in power between my 94-97 head or the 99 head I used on my old 500+ horsepower Miata. Both were stock and would create the same HP within 1-2hp. (Which could be just due to different days etc)

Interesting. You are the only person to ever claim this.
Savington is offline   Reply With Quote
Old 06-11-2008, 12:20 PM   #15
Elite Member
iTrader: (39)
 
Zabac's Avatar
 
Join Date: Sep 2007
Location: High Point NC
Posts: 4,854
Total Cats: 8
Default

Tod, headwork always helps, and a lot at that if done properly. End of story!

The only question is, is it worth it to you?

In your case, I think not. I don't see why you would want to drop $1000-$1500 (and yes that's how much real head work will cost) in a head if you still have a 2.5" exhaust and only pushing 12psi.
Taking a head of to just angle the vales will be as usefull as dropping the pan to do an oil change. If you're gonna build a head, build the whole thing, lighter vales, stronder retainers, stiffer springs, custom cams, adj. cam gears, bowl blending, port matching, unshrouding, etc...valve angling is not gonna even tickle your pickle.
There are so many other thing that you can do for more power for much cheaper that it just doesn't make sense to do any headwork yet.
Zabac is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Another Cast Manifold Corky Bell Prefabbed Turbo Kits 18 11-22-2016 10:01 PM
Need help - Stock Balancer and Fastforward overlay pulleys Frank_and_Beans Supercharger Discussion 13 09-12-2016 09:17 PM
Bad head gasket or ? shooterschmidty Engine Performance 8 09-30-2015 11:28 PM
Another Alternator thread ihiryu General Miata Chat 9 09-28-2015 11:22 AM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 02:00 AM.