More headwork Fail questions. - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 12-12-2008, 06:57 PM   #1
Elite Member
Thread Starter
iTrader: (8)
 
Join Date: Oct 2007
Location: Dallas
Posts: 1,841
Total Cats: 0
Default More headwork Fail questions.

Paul and everyone's 99 motors seem to be running really well.

We all know you really want to go lower compression on a build for boost. But the 99 seems to be holding up great at 9.5:1 compression ratio.

My brothers S/C car is the old style. The nose is not upgradeable. But we found away around that. The JR1.8 version had a smaller pulley. Something like 67.5mm I think. Bam 2psi. YAY!

And if we get the crank pulley 2more psi, for hopefully 8-9psi.

Head milling question

We thought about milling the head on his car some. Since he will never be high boost, we would like to gain some compression. 9.5:1 would be great, if there is enough clearance for the valves. Otherwise, whatever is safe for the valve clearance.

I know it isn't going to be crazy power, but the 99 is holding great with up to 14psi on 9.5:1

What do you think about this. Milling is cheap, and we are not going for stupid compression. Just somemore responce and low end. All for $20 milling from a family friend, gasket, and time.
Toddcod is offline   Reply With Quote
Old 12-12-2008, 07:00 PM   #2
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,892
Total Cats: 1,792
Default

do it.
Braineack is offline   Reply With Quote
Old 12-12-2008, 07:05 PM   #3
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,114
Total Cats: 351
Default

Considering the 1.6 was actually 8.8:1, you're not going to get 7/10 of a compression point out of milling the head. I had a head decked once and noticed no difference on the butt dyno. However, I'm a bitch.
hustler is online now   Reply With Quote
Old 12-12-2008, 07:12 PM   #4
Junior Member
iTrader: (1)
 
Join Date: Mar 2007
Location: South Florida
Posts: 491
Total Cats: -1
Default

One thing to keep in mind about milling an aluminum cylinder head is that once you remove material from head it will not be able to deal with overheating situations as well as when it is at it's normal deck thickness. Mazda recommends a new cylinder head if it is warped by more than .006".

Take it for what it's worth.


Tony
mrtonyg is offline   Reply With Quote
Old 12-12-2008, 09:10 PM   #5
Elite Member
Thread Starter
iTrader: (8)
 
Join Date: Oct 2007
Location: Dallas
Posts: 1,841
Total Cats: 0
Default

Hmmm.............. We'll probably just go a head and get the crank pulley.. And save that thought for when he is tired of the new found power.

Is there a stronger material, but thinner head gasket?

Dyno's sometimes read different from week to week, and place to place. I had a GSXR1000 read 143 hp one place and 153 another. But I did think it gained some power after 7000 miles.

Hustler could you feel any difference?
Toddcod is offline   Reply With Quote
Old 12-13-2008, 12:00 AM   #6
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,367
Total Cats: 1,331
Default

Quote:
Originally Posted by hustler View Post
Considering the 1.6 was actually 8.8:1, you're not going to get 7/10 of a compression point out of milling the head. I had a head decked once and noticed no difference on the butt dyno. However, I'm a bitch.
The 1.6s were 9.0s. Only 94-95s had the flat-topped 8.8 pistons.
Savington is offline   Reply With Quote
Old 12-13-2008, 02:12 AM   #7
Elite Member
iTrader: (1)
 
NA6C-Guy's Avatar
 
Join Date: Feb 2008
Location: Birmingham Alabama
Posts: 8,038
Total Cats: 43
Default

If it were me, and I was going to have a reason to pull the head other than to mill the head, I would do it while it was off. I wouldnt remove it just for that reason though. Im quite glad I did mine though, since I think higher compression will be helpful since I only have 8.8:1, and dont plan to do over about 8-10psi on a 2554. I had .015 removed from mine, and will probably have another .005 removed when I bring it to the machine shop again to remove some minor dings in the surface from sliding it on a table top. Though a whole different animal, I had the head from a Honda Prelude milled .020 years ago, and did notice a slight seat of the pants gain(very slight, maybe). It was n/a though, making maybe 160-170whp, already at 10.5:1 if I remember correctly, so it may have gone up to upper 10's or low 11's. Not sure that you would be able to tell a thing with an over 200whp s/c car though, not likely.
NA6C-Guy is offline   Reply With Quote
Old 12-13-2008, 03:10 AM   #8
Elite Member
iTrader: (24)
 
Join Date: Jun 2007
Location: Sherman Oaks, CA
Posts: 4,481
Total Cats: 3
Default

its useless and unsafe. dont do it.
UrbanSoot is offline   Reply With Quote
Old 12-13-2008, 03:22 AM   #9
Elite Member
iTrader: (1)
 
NA6C-Guy's Avatar
 
Join Date: Feb 2008
Location: Birmingham Alabama
Posts: 8,038
Total Cats: 43
Default

Quote:
Originally Posted by UrbanSoot View Post
its useless and unsafe. dont do it.
Why do you say it is unsafe?
NA6C-Guy is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Raleigh: Fiberglass headlight scope, 1.6L ECU, AFM, Hardtop latches, more bigmackloud Miata parts for sale/trade 13 09-22-2017 01:34 PM
1994 Spec Miata Race Car SM/SM2/SSM For Sale Quinn Cars for sale/trade 6 10-23-2016 08:58 AM
Brakes ???? tomiboy Race Prep 124 11-02-2015 04:55 PM
Bad head gasket or ? shooterschmidty Engine Performance 8 09-30-2015 11:28 PM
2003 VVT Head/Valve Cover/Actuator/Coil Packs - Low Miles! - $250 StratoBlue1109 Miata parts for sale/trade 7 09-24-2015 04:50 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 08:06 PM.