Compression test results - 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 10-27-2013, 02:41 PM   #1
Junior Member
Thread Starter
 
Join Date: Aug 2013
Location: Ohio
Posts: 78
Total Cats: -7
Default Compression test results

I did a compression test on my 00 today and got the following 200,196,200,202 on a warm engine. From online reading these seem to be nice consistent numbers. I was concerned about my virtual dyno numbers of 140/124. I'm thinking I need to ditch my RL header for an RB and possibly my Monster flow intake for a coldside set-up.

Attached Thumbnails
Compression test results-2mhflop.jpg  
6speed is offline   Reply With Quote
Old 10-27-2013, 05:19 PM   #2
Moderator
iTrader: (11)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 15,663
Total Cats: 1,560
Default

Those are awfully low dyno numbers for a turbo car.
sixshooter is online now   Reply With Quote
Old 10-27-2013, 05:34 PM   #3
Elite Member
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,009
Total Cats: 583
Default

Compression looks great. From your sig, you're normally aspirated. Those are decent numbers in that case. Remember, it's wheel HP/TQ, after drivetrain losses. Add 15-20% to get HP/TQ at the crank.
hornetball is offline   Reply With Quote
Old 10-27-2013, 07:55 PM   #4
Junior Member
Thread Starter
 
Join Date: Aug 2013
Location: Ohio
Posts: 78
Total Cats: -7
Default

The car is n/a, not forced induction. I was hoping for closer to 150whp. I experimented with a short coldside intake today. As the experts have said many times, I lost torque and, in my case, topend as well. I'm going to keep tinkering and see what I get.
6speed is offline   Reply With Quote
Old 10-27-2013, 08:13 PM   #5
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,175
Total Cats: 2,578
Default

what mods?
18psi is offline   Reply With Quote
Old 10-27-2013, 08:27 PM   #6
Junior Member
iTrader: (9)
 
Join Date: Jan 2007
Posts: 455
Total Cats: 3
Default

Some good info on intake diameters/lengths.

[NA] 135whp with stock NA8 long block - MX-5 Miata Forum
sv650_ck is offline   Reply With Quote
Old 10-27-2013, 09:04 PM   #7
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: 26,317
Total Cats: 1,914
Default

Quote:
Originally Posted by 6speed View Post
I was hoping for closer to 150whp
Why?

The dyno chart you have posted is excellent for what, based on your signature, I assume to be a mostly stock 2000 engine with a few bolt-ons.

For what it's worth, I would not expect a significant improvement from replacing the riceland exhaust manifold with a racingbeat unit. The materials quality will be a bit better, but there's not a significant difference between the two in terms of design.
Joe Perez is online now   Reply With Quote
Old 10-27-2013, 09:24 PM   #8
Junior Member
Thread Starter
 
Join Date: Aug 2013
Location: Ohio
Posts: 78
Total Cats: -7
Default

Emilio from 949 racing typically quotes about 155-160 for a healthy 01+ block with a fresh 99/00 head with the bolt-on's I have . I was thinking with a .5 less compression I would see maybe 145-150. Since my shortblock seems ok, I may invest in a set of cams from somewhere. Any Idea's or input is appreciated. I know this is "Turbo Miata" but this site is much more tech. oriented than m.net.
6speed is offline   Reply With Quote
Old 10-27-2013, 11:06 PM   #9
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: NH
Posts: 9,091
Total Cats: 90
Default

Tune might be a bit suspect. Get rid of those lean bumps. Have you tuned the spark timing and decided on a target afr on the dyno?
Leafy is offline   Reply With Quote
Old 10-27-2013, 11:33 PM   #10
Junior Member
Thread Starter
 
Join Date: Aug 2013
Location: Ohio
Posts: 78
Total Cats: -7
Default

I have tuned the timing tables. I'm running roughly 33-34 degree's total timing under WOT in the upper rpm's. I have also played with AFR's between @ 12.4 -13.4 on the chance my AEM wideband was off. The AFR changes netted me nothing really +- 1-2 whp, while more timing just set my knock sensor off. The spike around 5500 corresponds to a drop in map readings that I think is from an intake resonance. I have adjusted my target AFR in that region to try to counter the spike.
Attached Files
File Type: msq CurrentTune.msq (176.0 KB, 70 views)

Last edited by 6speed; 10-28-2013 at 05:46 AM.
6speed is offline   Reply With Quote
Old 10-29-2013, 01:47 PM   #11
Junior Member
 
Join Date: Sep 2011
Location: finger lakes NY
Posts: 444
Total Cats: 17
Default

Quote:
Originally Posted by 6speed View Post
I was concerned about my virtual dyno numbers of 140/124.
Virtual Dyno is great for before/after comparisons, but the absolute numbers aren't going to be accurate unless you get all of the input parameters right; weight, tire diameter, gear ratios...

Even wheel dynos can vary by more than the 5 or 10 whp that you're talking about.
DaveC is offline   Reply With Quote
Old 10-29-2013, 03:17 PM   #12
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,175
Total Cats: 2,578
Default

All dyno's will vary all the time. Stressing over anything sub-5hp is a waste of time IMO.
That said, I've so far had great luck with VD with over 5 runs all showing within 1-2hp of each other.

IF that plot of yours is accurate, that's pretty impressive for what it is.
I have a mint 01 engine with a 3" midpipe and e85 that I made 122/117 with repeatedly, your 140/124 sounds about right for the mods. I run little bit less timing though, just because 10:1

*edit: kinda curious about your spark map: why run 30* in the cruise cells and 33 at wot? Also why are your maps scaled to 240kpa? Planning for boost soon?
18psi is offline   Reply With Quote
Old 10-29-2013, 03:39 PM   #13
Junior Member
Thread Starter
 
Join Date: Aug 2013
Location: Ohio
Posts: 78
Total Cats: -7
Default

Quote:
Originally Posted by 18psi View Post
*edit: kinda curious about your spark map: why run 30* in the cruise cells and 33 at wot? Also why are your maps scaled to 240kpa? Planning for boost soon?
My MS3 base map came scaled to 240kPa from Rev and I haven't bothered to change it yet. As far as my cruise cell advance numbers, it's still a work in progress and I'm just not sure how high to go with light load timing. Anything done to your C5?
6speed is offline   Reply With Quote
Old 10-29-2013, 04:10 PM   #14
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,175
Total Cats: 2,578
Default

Bone stock and recently sold lol. Gotta update the sig.

What I'm saying is: if you safely ran 33* at 100kpa you should be able to run AT LEAST that much in the cruise cells.

Both your tables need cleaning up and re-scaling, but that stuff is fairly straightforward so no biggie
18psi is offline   Reply With Quote
Old 10-29-2013, 05:59 PM   #15
Junior Member
Thread Starter
 
Join Date: Aug 2013
Location: Ohio
Posts: 78
Total Cats: -7
Default

Look any better? I'm thinking it still needs some timing advance in the 40-55 load 3-4k range. I Don't know why I hadn't rescaled sooner, so I could use the full resolution. Thanks so much for pointing that out.
Attached Files
File Type: msq my car 10-29-13 rescaled.msq (175.8 KB, 69 views)

Last edited by 6speed; 10-29-2013 at 07:33 PM.
6speed is offline   Reply With Quote
Old 11-02-2013, 12:00 AM   #16
Supporting Vendor
iTrader: (3)
 
emilio700's Avatar
 
Join Date: May 2005
Posts: 5,311
Total Cats: 1,334
Default

Quote:
Originally Posted by 6speed View Post
Emilio from 949 racing typically quotes about 155-160 for a healthy 01+ block with a fresh 99/00 head with the bolt-on's I have .
?
Not my quote, perhaps someone elses. Consult the FSM for compression numbers. USDM NB2 should be around 205psi when new, broken in and warm. Leakdown under 2% for new motors. Most used NB's we see are in the 140-170psi range. They'll still run OK but make less power. Most compression loss from normal wear is from exhaust valve seats. Often times a <100k motor with medium compression can get most of it back with just a valve job.

Sorry for jumping in the thread out of nowhere. As you were.
emilio700 is offline   Reply With Quote
Old 11-02-2013, 12:08 AM   #17
Moderator
iTrader: (11)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 15,663
Total Cats: 1,560
Default

So, a valve job nets a decent ROI in most cases? Are the exhaust valves bad at the seat or bent at the stem typically? I ask because I heard they bend easily.
sixshooter is online now   Reply With Quote
Old 11-02-2013, 01:02 AM   #18
Junior Member
Thread Starter
 
Join Date: Aug 2013
Location: Ohio
Posts: 78
Total Cats: -7
Default

Quote:
Originally Posted by emilio700 View Post
?
Not my quote, perhaps someone elses. Consult the FSM for compression numbers. USDM NB2 should be around 205psi when new, broken in and warm. Leakdown under 2% for new motors. Most used NB's we see are in the 140-170psi range. They'll still run OK but make less power. Most compression loss from normal wear is from exhaust valve seats. Often times a <100k motor with medium compression can get most of it back with just a valve job.

Sorry for jumping in the thread out of nowhere. As you were.
I meant 155-160 whp, not psi compression numbers. Perhaps I'm still wrong though, heck I don't know. Regardless I feel good about my 200ish psi results.
6speed is offline   Reply With Quote
Old 11-02-2013, 11:05 AM   #19
Supporting Vendor
iTrader: (3)
 
emilio700's Avatar
 
Join Date: May 2005
Posts: 5,311
Total Cats: 1,334
Default

Quote:
Originally Posted by sixshooter View Post
So, a valve job nets a decent ROI in most cases? Are the exhaust valves bad at the seat or bent at the stem typically? I ask because I heard they bend easily.
Worn seats. Long term, the #4 cylinder (runs hottest) has faster ring wear than the others. So usually its exhaust seat wear, some intake seat wear then ring wear.
emilio700 is offline   Reply With Quote
Old 11-04-2013, 09:02 AM   #20
Elite Member
iTrader: (5)
 
Join Date: Dec 2010
Location: Raleigh, NC
Posts: 1,970
Total Cats: 49
Default

Quote:
Originally Posted by 6speed View Post
The car is n/a, not forced induction. I was hoping for closer to 150whp. I experimented with a short coldside intake today. As the experts have said many times, I lost torque and, in my case, topend as well. I'm going to keep tinkering and see what I get.
your cold side intake needs to be longer. I vaguely remember 21" as the ideal length for us? someone can correct me if I am off there.

Also, for your mods, the expected power is 140-145whp.

Last edited by Seefo; 11-05-2013 at 11:12 AM.
Seefo is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 57 07-19-2017 05:11 PM
1994 Spec Miata Race Car SM/SM2/SSM For Sale Quinn Cars for sale/trade 6 10-23-2016 08:58 AM
Low oil pressure after 1.8 swap and new turbo setup JesseTheNoob DIY Turbo Discussion 15 09-30-2015 03:44 PM
3rd Time's a Charm...hopefully. zephyrusaurai Meet and Greet 2 09-28-2015 11:59 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 11:11 AM.