T-78 dyno results w/ ported motor
07-15-04, 10:23 PM
#27
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Thread Starter
Jason: does the rx7 store use a mustang dyno or a dyno jet? Just curious
Also what could be the cause of the plugs burning different? Front rotor leading is black and wet while the rear leading is a nice brown color.
Howard: the tuner said he tried lowering the timing and the car would not run properly. One of the big problems may be the fact neither the tuner nor the builder had ever used a Microtec LT-8 before, he had only ever used a power fc. I keep getting told that if I had gone with a power fc I would not of had as many problems
The car also likes to stall when I put it in neutral from second gear. (ie: coming up to a light in 2nd @ 2k rpm and put it into neutral before stopping) when put in neutral the car will sometimes just die.
Erik
Also what could be the cause of the plugs burning different? Front rotor leading is black and wet while the rear leading is a nice brown color.
Howard: the tuner said he tried lowering the timing and the car would not run properly. One of the big problems may be the fact neither the tuner nor the builder had ever used a Microtec LT-8 before, he had only ever used a power fc. I keep getting told that if I had gone with a power fc I would not of had as many problems
The car also likes to stall when I put it in neutral from second gear. (ie: coming up to a light in 2nd @ 2k rpm and put it into neutral before stopping) when put in neutral the car will sometimes just die.
Erik
07-15-04, 10:45 PM
#28
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Thread Starter
Howard: regarding the cranking compression, When we checked the motor again today this time with teh throttle open one rotor was @ 65psi while the other was @ 60 psi. What do you think?
07-15-04, 11:25 PM
#29
I suggest calling a tuner like Steve Kan about this.
www.gothamracing.com
www.gothamracing.com
07-15-04, 11:29 PM
#30
Lives on the Forum
Compression that low would cause excessive blow-by, which can easily cause the increase pressure in the "crankcase".
You still don't mention the shop that did the work?
-Ted
You still don't mention the shop that did the work?
-Ted
07-16-04, 01:33 AM
#31
woa..only 60 and 65psi? thats real low man. according to the mazda compression tester, unless you are cranking below 200 rpm, its considered "bad" by mazda specs. 200 rpm should be around 5.0 bar of compression minimum, or about 72 psi for those of you using the queens' measurements....hope it turns out ok for you....
07-16-04, 01:35 AM
#32
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Thread Starter
I am still trying to figure out what is going on with the car and until i get a better idea I don't want to start mentioning who built the car.
The poor performance could be due to a number of smaller things, a tuning problem or it could be an engine issue in which case the builders reaction to the issue will determine how I proceed.
The main questions are:
1) Is cranking compression irrelevent compared to compression under boost as I have been told by the builder?????
2) Why are the two leading plugs not buring the same?
3) According to the builder to help prevent detonation the car is not running off of trailing plugs.
What impact if any is this having on performance? I have been told none, since they are only used for emissions.
4) How are these hp numbers compared to others run on a mustang dyno?
5) Why is the car leaking oil under boost? and from where? Since the new greddy oil pressure gauge has stopped working twice could the oil be leaking from the sending unit? This was suggested to me, but if it was leaking fromthe sending unit under the oil filter wouldn't it leak during idle and normal driving? or no?
Any help for any of these questions is appreciated, I just want my car to run properly for the mods, time and money put into it.
Erik
The poor performance could be due to a number of smaller things, a tuning problem or it could be an engine issue in which case the builders reaction to the issue will determine how I proceed.
The main questions are:
1) Is cranking compression irrelevent compared to compression under boost as I have been told by the builder?????
2) Why are the two leading plugs not buring the same?
3) According to the builder to help prevent detonation the car is not running off of trailing plugs.
What impact if any is this having on performance? I have been told none, since they are only used for emissions.
4) How are these hp numbers compared to others run on a mustang dyno?
5) Why is the car leaking oil under boost? and from where? Since the new greddy oil pressure gauge has stopped working twice could the oil be leaking from the sending unit? This was suggested to me, but if it was leaking fromthe sending unit under the oil filter wouldn't it leak during idle and normal driving? or no?
Any help for any of these questions is appreciated, I just want my car to run properly for the mods, time and money put into it.
Erik
07-16-04, 12:47 PM
#33
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compression will be lower and takes longer to get seated if using old rotor housing. also, the tolerances on who milled the rotors will affect compression as well. Blow by is generally cause by either a stuck side seal or corner seal. I would give at least 1500 miles to see if the compression stays the same.
07-18-04, 09:47 AM
#34
send ccarlisi your info and mods , type of port, boost levels it started losing compression or sounding funny on dyno etc. We are making a spread sheet to find if there is a common link. Also check this thread. http://www.nopistons.com/forums/inde...howtopic=44700
07-18-04, 12:38 PM
#36
Originally Posted by black93RX7
I am still trying to figure out what is going on with the car and until i get a better idea I don't want to start mentioning who built the car.
The poor performance could be due to a number of smaller things, a tuning problem or it could be an engine issue in which case the builders reaction to the issue will determine how I proceed.
The main questions are:
1) Is cranking compression irrelevent compared to compression under boost as I have been told by the builder?????
2) Why are the two leading plugs not buring the same?
3) According to the builder to help prevent detonation the car is not running off of trailing plugs.
What impact if any is this having on performance? I have been told none, since they are only used for emissions.
4) How are these hp numbers compared to others run on a mustang dyno?
5) Why is the car leaking oil under boost? and from where? Since the new greddy oil pressure gauge has stopped working twice could the oil be leaking from the sending unit? This was suggested to me, but if it was leaking fromthe sending unit under the oil filter wouldn't it leak during idle and normal driving? or no?
Any help for any of these questions is appreciated, I just want my car to run properly for the mods, time and money put into it.
Erik
The poor performance could be due to a number of smaller things, a tuning problem or it could be an engine issue in which case the builders reaction to the issue will determine how I proceed.
The main questions are:
1) Is cranking compression irrelevent compared to compression under boost as I have been told by the builder?????
2) Why are the two leading plugs not buring the same?
3) According to the builder to help prevent detonation the car is not running off of trailing plugs.
What impact if any is this having on performance? I have been told none, since they are only used for emissions.
4) How are these hp numbers compared to others run on a mustang dyno?
5) Why is the car leaking oil under boost? and from where? Since the new greddy oil pressure gauge has stopped working twice could the oil be leaking from the sending unit? This was suggested to me, but if it was leaking fromthe sending unit under the oil filter wouldn't it leak during idle and normal driving? or no?
Any help for any of these questions is appreciated, I just want my car to run properly for the mods, time and money put into it.
Erik
Double check the large bolt holding the oil line on. It is right below the oil filter and is prone to leaking.
Compression should be checked while cranking with the throttle opened the whole way. Compression should also be checked on a cold and a warm motor and the two values compared.
Double check that your PCV valve is not sticking open as that will cause the crankcase to pressurize.
07-18-04, 01:20 PM
#37
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Originally Posted by black93RX7
I am still trying to figure out what is going on with the car and until i get a better idea I don't want to start mentioning who built the car.
2) Why are the two leading plugs not buring the same?
Erik
2) Why are the two leading plugs not buring the same?
Erik
07-18-04, 01:54 PM
#38
Originally Posted by CCarlisi
This could be caused by a difference in flow between your front and rear rotor fuel injectors.
By the way, not running the trailing will cause the EGT's to be higher, up to 1500 to 2000 degrees higher. I know this becuase I tested it this weekend.
By the way Chris, have Mike give me a call. I lost his number, TY.
07-18-04, 03:14 PM
#40
Rotary Enthusiast
Erik im wondering about somthing, how old is the engine, and how was it put back togheter if it was rebuilt. And did u use old side seals and springs.
Cause the only way u can get compresion into the oil is two ways. U have a crack in a side wall. Or it could be a stuck side/corner seal. Or maybe a broken side/corner seal.
A freind of mine forgot to put in one side seal when doing a rebuild, and he was blowing black smoke at wot, and the oil did push up trough the oil level pin. And out trough the breathing line to the air filter.
But at 60 psi of compresion i would do a rebuild. Every thing under 90 is bad. Even though the car runs fine, and u don't have the broken apex syndrom, i would do a rebuild.
It would be a preventing insertion. Instead of waiting until somthing more breaks, and maybe destroys a rotor and a rotor house.
Oh and if u forgot to put somthing in when rebuilding the engine, please remeber it this time.
Oh and i pulled 321rwhp and 287lbs of tourque at 14 psi with original twins, so somthing is wrong. And im pulling about 450rwhp now with a TD06H-25G
Cause the only way u can get compresion into the oil is two ways. U have a crack in a side wall. Or it could be a stuck side/corner seal. Or maybe a broken side/corner seal.
A freind of mine forgot to put in one side seal when doing a rebuild, and he was blowing black smoke at wot, and the oil did push up trough the oil level pin. And out trough the breathing line to the air filter.
But at 60 psi of compresion i would do a rebuild. Every thing under 90 is bad. Even though the car runs fine, and u don't have the broken apex syndrom, i would do a rebuild.
It would be a preventing insertion. Instead of waiting until somthing more breaks, and maybe destroys a rotor and a rotor house.
Oh and if u forgot to put somthing in when rebuilding the engine, please remeber it this time.
Oh and i pulled 321rwhp and 287lbs of tourque at 14 psi with original twins, so somthing is wrong. And im pulling about 450rwhp now with a TD06H-25G
07-18-04, 04:06 PM
#41
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Thread Starter
jantore: The engine is a brand new rebuild with new rotor housings and seals. The car has only been on the road for a month. I have put at least 5000 miles on the new engine so it should be fully broken in.
When I told the builder about the low compression he said that cranking compression does not matter only compression under fire. He said as long as each rotor is the same it doesn't matter.
I do not believe what he is saying. For example if my new engine is at 60 psi in each rotor while another new engine is at 90 psi cranking compression, under fire wouldn't my engine still have lower compression than the one with 90 psi
I paid approx $3700 usd for the engine rebuild with all new parts (rotor housings, seals, dowell pins, street port) and I am only getting 60 psi in each rotor. I think I got screwed and all the builder tells me is cranking compression doesn't matter.
CCarlisi: I was thinking the plugs not burning the same is either from insufficient spark or a bad primary injector. I was origionally told the stock primaries were flow tested but then the when I asked the builder about this problem he said they were only cleaned
zkeller: what would be the impact of higher EGT's?
What do the rest of you guys have for cranking compression on your motors? and do you believe the statement by my builder that cranking compression does not matter?
if the motor is bad i want it done again but not by the same shop; but I also don;t want to pay for another rebuild because it was not done right the first time. anyway I'm ranting
thanks
Erik
When I told the builder about the low compression he said that cranking compression does not matter only compression under fire. He said as long as each rotor is the same it doesn't matter.
I do not believe what he is saying. For example if my new engine is at 60 psi in each rotor while another new engine is at 90 psi cranking compression, under fire wouldn't my engine still have lower compression than the one with 90 psi
I paid approx $3700 usd for the engine rebuild with all new parts (rotor housings, seals, dowell pins, street port) and I am only getting 60 psi in each rotor. I think I got screwed and all the builder tells me is cranking compression doesn't matter.
CCarlisi: I was thinking the plugs not burning the same is either from insufficient spark or a bad primary injector. I was origionally told the stock primaries were flow tested but then the when I asked the builder about this problem he said they were only cleaned
zkeller: what would be the impact of higher EGT's?
What do the rest of you guys have for cranking compression on your motors? and do you believe the statement by my builder that cranking compression does not matter?
if the motor is bad i want it done again but not by the same shop; but I also don;t want to pay for another rebuild because it was not done right the first time. anyway I'm ranting
thanks
Erik
07-18-04, 06:46 PM
#46
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im having freddy rebuild mine... i gotta t04,greddy 3 row, etc i have a power fc for my 90 turbo rx7, just need a datalogit and wideband, already have egt and powerfc knock sensor.... never seen your car anywhere, i thought about getting engine rebuilt outta the province, but when things start to go wrong, its a big hassle.... i also read for a whole year to tune, because i dont trust anyone tuning a rotary in canada alltogether. i figured power fc is easier so i dont have to rip apart my wiring harness. microtech is just as good, just a personal preference i guess. it'll be my first time tuning when i get my car out,this week. mods going to go on next month after all broken in.. nice to see someone finally did a t78 fd in winnipeg, your going to lay the smackdown on alot of ppl once you have everything running right...
07-18-04, 07:53 PM
#47
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Thread Starter
I was at fred's alot last week, that is where I did the compression test. I was origionally going to have fred do my motor but he was pretty busy and I wanted it on the road asap. Can 't wait to see your car once its on teh road is it the nice red 2nd gen?
By the way I think I found my oil leak. I took off the oil filler neck and there was no gasket between the neck and the block plus one of the bolts was stripped. This must be it, I targeted this area b/c I had placed a piece of cardboard under the neck and after a little driving it was soaked with oil. I will reseal it a see what happens.
one problem down.
next I will work on why the plugs are not burning the same and then the main issue of low cranking compression.
Chris you should pm me
By the way I think I found my oil leak. I took off the oil filler neck and there was no gasket between the neck and the block plus one of the bolts was stripped. This must be it, I targeted this area b/c I had placed a piece of cardboard under the neck and after a little driving it was soaked with oil. I will reseal it a see what happens.
one problem down.
next I will work on why the plugs are not burning the same and then the main issue of low cranking compression.
Chris you should pm me
07-18-04, 08:18 PM
#49
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you can email me @ edalmar93@hotmail.com, we should talk. Do you have messenger?
07-18-04, 08:31 PM
#50
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yeah you can msn me at chrisyng@hotmail.com