Single Turbo Discussion Area for discussing single turbo RX-7's.

Losing Compression On Dyno, Any Ideas?

Thread Tools
 
Search this Thread
 
Old May 9, 2004 | 07:44 PM
  #91  
Judge Ito's Avatar
Senior Member
 
Joined: Jan 2002
Posts: 1,915
From: NJ USA
Default

Steve, I don't feel your tunning of the timing maps are OFF. I'm thinking the PFC is not correctly adjusting timing advance under boost and keeping the engine running a retard timing under boost causing Xtremely high EGT's. Next dyno session I'll be there helping Mike with his car. I'll be checking proper timing advance under boost.



The exhaust port opening is under 5mm vs the stock exhaust port opening. It opens 2mm earlier then the stock port. I have almost seen it all in the world of porting. Done just about everything. Big port's vs small ports and I've yet to see this problem Mikes car is having. I've only seen warped apex seals in 2 cases. Lean air fuel mixture or high EGT's ... The air fuel ratio mixture has been addressed in this case, but the cause of high egt's has not been checked through ignition timing under high boost.
Old May 9, 2004 | 08:30 PM
  #92  
Badog's Avatar
Senior Member
 
Joined: Jul 2001
Posts: 273
From: oHIo
Default

Need a log. Got any of the old ones? Would be able to tell in the log what was happening with IGN. If a sensor went caca, that could take you down up to 6 degrees advance alone. Couple of sensors....maybe more.



I like that Mike is getting EGT bung(s) now. That is going to be nice to watch.
Old May 11, 2004 | 09:45 PM
  #93  
Maxt's Avatar
Senior Member
 
Joined: Feb 2003
Posts: 564
From: Calgary
Default

Couple of questions, how is your fuel rail hooked up(plumbed), and does the POwer FC fire the injectors in batch or sequential?....Maxt
Old May 12, 2004 | 10:53 PM
  #94  
rx7tt95's Avatar
Senior Member
 
Joined: Jul 2001
Posts: 629
From: S. Florida
Default

One thing with Russ' engine is that he specifically requested that Pettit port the exhaust. Cam was reluctant but Russ believes he did port the exhaust as well as the intake. Russ runs a Power FC with a 550/1300 combo. He does not have an EGT guage either. The problem on his engine is being looked at by Pettit. No final conclusions yet as the engine has not been opened up. I'll have to double check, but Russ may have mentioned some Power FC issue. Too tired to remember. I'll ask or Russ, if you're reading, chime in :-)



I know of one other car that has "issues" similar to what's been described but the car has yet to even make it to the dyno. It seems to have some of the same issues under boost and the need for much fuel to run properly. Installing the same maps from my car doesn't get things working too correctly.
Old May 13, 2004 | 08:24 AM
  #95  
83turbo's Avatar
Senior Member
 
Joined: Nov 2003
Posts: 480
Default

Does the PFC allow you to set trigger edge for the ignition, and if so is it set correctly? Just a guess.
Old Apr 17, 2005 | 03:42 PM
  #96  
alberto_mg's Avatar
Senior Member
 
Joined: Jun 2003
Posts: 101
From: NYC+LI
Default

was there ever a final conclusion about what caused Mike's seals to warp?
Old Apr 18, 2005 | 01:53 PM
  #97  
pluto's Avatar
Member
 
Joined: Dec 2001
Posts: 98
Default

there were only a few things I could think of that could cause an apex seals to warp.



1.) warp rotor housing

2.) soft apex seals

3.) bad OMP

4.) too high of EGT temp

5.) not bevel on closing of exhaust port



other than that, i coulnd't think of anything else.









[quote name='alberto_mg' date='Apr 17 2005, 12:42 PM']was there ever a final conclusion about what caused Mike's seals to warp?

[snapback]701032[/snapback]

[/quote]
Old Apr 20, 2005 | 07:50 AM
  #98  
ccarlisi's Avatar
Senior Member
 
Joined: Aug 2002
Posts: 502
Default

[quote name='alberto_mg' date='Apr 17 2005, 12:42 PM']was there ever a final conclusion about what caused Mike's seals to warp?

[snapback]701032[/snapback]

[/quote]



Hi Alberto I heard about your problem. It must have seemed eerily familiar after witnessing Mike go through the same thing on the same dyno the previous year.



We still don't know what caused Mike's problem. I purchase the car from him after he went through the last motor. The Ito motor was pulled and examined by another builder. For what it's worth, the other builder made the following observations:



1. Despite Mike being told 2 piece seals were used in his motor the builder found 3 piece seals -so I guess the new apex seals were not the problem as we previously suspected.

2. The clearance on the side seals was out of spec

3. One of the irons was severely worn.
Old Apr 20, 2005 | 08:49 AM
  #99  
alberto_mg's Avatar
Senior Member
 
Joined: Jun 2003
Posts: 101
From: NYC+LI
Default

thanks chris. i was going to reach out to you, but too busy with work, classes and the wedding.



that day was kinda like watching someone crush their ***** while trying to hop over a fence. except that person was now me.



i'm keeping low key about it till I get things settled with the involved parties. hopefully it doesn't turn into an unprofessional pissing match.
Old Mar 12, 2015 | 12:19 PM
  #100  
junito-1's Avatar
Junior Member
 
Joined: Mar 2015
Posts: 1
Default Re: Losing Compression On Dyno, Any Ideas?

Any updates? Im having same issue.with a factory port engine. Whats ironic.is that it happened at 13-14psi.for me.as well.

Last edited by junito-1; Mar 12, 2015 at 12:24 PM.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
TII777
2nd Generation Specific
6
May 9, 2004 11:56 PM
Josam01
2nd Generation Specific
4
Apr 23, 2004 03:20 PM
Josam01
2nd Generation Specific
2
Apr 21, 2004 04:53 PM
loudazzrx7
2nd Generation Specific
1
Sep 27, 2003 07:32 PM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 



All times are GMT -5. The time now is 12:49 PM.