Blown rings

[hybridGS]

So I find out this morning from the dyno shop that my piston rings are blown. The car hit 245 and they noticed that the oil dip stick was getting blown up at higher rpms. So now I am looking at 2,300 dollars for new pistons and getting the block rebore (that shops quote). Thats alot of money, I can get a whole engine built for cheaper than that ( http://www.vtengines.com/ShortMitsu.htm ). The only problem is i have no idea how much it would be to swap the engines. If any body has a suggestion as to wether it would be better to fix the existing engine or just replace it I would appriciate it. Also the engine had less then 10k since the last time it was rebuilt any suggestions on how to keep from blowing it again? I don't know for sure if it was done by me or the previous owner.

 

[Kirby]

What do you mean it was rebuilt? Do you mean stock parts? If I were you and you have stock parts in the engine then I would just rebuild with forged internals. That way you can run some serious boost. So I would buy the one from VT and drop it in the car yourself, or get a quote on what the labor would cost to install the new motor. Have you checked your compression though? Don't just take the shops word for it find out for your self.

 

[hybridGS]

actually the car was buit up for turboing, it given je cold forged and crower rods. I know there is a serious problem because it is missing about 100hp from similar set ups and hitting power late in the rpm range.

 

[Kirby]

Well your rings should last much more than 10k miles. Do some checking into this situation. Was it running lean at all? What kind of information can you give me here? It may just be a head gasket which is much cheaper than rebuilding. And a HG issue can cause the dipstick condition you mentioned eairler. So trust me DO NOT JUST LET THIS SHOP TELL YOU WHAT YOU DO HERE. Find out for yourself. This may be a $300-600 fix.

 

[hybridGS]

It was actually runing rich (since I owned it). There was alot of problems with it (2 exhaust leaks, fuel leak, vacume leak) thats why it's in the shop so it's hard to tell if anything specificly went wrong. I think (if they are blown) they were blown when I got the car. i don't claim to know much about engines so how would a leak in the head gasket cause the crank crase to get pressurized. Could you also define an hg condition. the reasen I posted is so that i could get feedback on what the problem could be, so thanks for the input. How would I go about checking to see if the gasket is leaking? The shop was supose to do a pressure test to find the vacume leak I would think this would expose that I will have to check with them.

 

[Kirby]

A hg issue is a head gasket issue. Basicly if the HG blows and allows air into the oil passages it will put air into your crank case and pop up your dipstick. If it goes into the coolant passages then your coolant will usually bubble out of the system. If your HG is blown then either of these things are possible. If you do a compression test on the car it will tell you if you have any low cilinders, if you do then you can put a little oil in the low one and see if the compression comes up again. If it comes up then your rings might be it, however if it stays the same then it's prolly your HG. Testing for a vac leak will not tell you if your HG is blown. You have to get a comp tester and test the compression. Go to www.2gnt.com and search for compression test it will tell you everything you need to know. Unless you were running lean as hell or low on oil then your rings should be fine. Any rings that wear out in less than 10,000 miles must be really low quality, and it dosen't sound like the previous owner was a cheapskate. The other thing you have to realize is that now you own a high performance DSM so you need to start learning how to find and fix stuff yourself, or else people will be taking some serious advantade of you. You need to spend a lot of time in the turbo section of www.2gnt.com to learn about your car. No reputable shop will tell you you have blown rings without running tests to confirm it first. So they should have to run a leak down test or a compression test to know for shure. Do you have any coolant in the oil, or oil in the coolant?

 

[hybridGS]

I like to work on the car, however I am currently a student so space time and equipment are not readily available. I agree that the shop should check that stuff, but I really don't know of too many shops that specialize in import performance that i could take it to ( the car is currently at balanced performance just north of atlanta ). I do seem to be running low on coolant avery once in a while, although there is a big hole in the side of the resivior ( it fell on the ps pully one day) although there never was coolant in the resivior before then. There seems to be plenty of coolant in the radiator as the car usually runs a hair below normal. I still don't understand what you mean with the hg issue maby you could define this for me and how it would cause me to miss alot of hp. The reason I was quick to assume the rings is becasue there is an 80hp N02 spray set up which the owner told me he never used ( since rebuilding as turbo). However when i bought the car he had reinstalled the stock injectors and lowered the boost to 8 lbs. I put the 440s in and turned up the boost to 20 psi and thats when i could feel the power band felt slow and definitly too low. As for the fluids mixing i recently changed the oil and did not notice ( i am under the assumption it would be visibly thinned) anything out of the ordinary, I have not checked the coolant and I won't have access to the car untill this weekend.

 

[Kirby]

Originally posted by hybridGS
I like to work on the car, however I am currently a student so space time and equipment are not readily available. I agree that the shop should check that stuff, but I really don't know of too many shops that specialize in import performance that i could take it to ( the car is currently at balanced performance just north of atlanta ). I do seem to be running low on coolant avery once in a while, although there is a big hole in the side of the resivior ( it fell on the ps pully one day) although there never was coolant in the resivior before then. There seems to be plenty of coolant in the radiator as the car usually runs a hair below normal. I still don't understand what you mean with the hg issue maby you could define this for me and how it would cause me to miss alot of hp. The reason I was quick to assume the rings is becasue there is an 80hp N02 spray set up which the owner told me he never used ( since rebuilding as turbo). However when i bought the car he had reinstalled the stock injectors and lowered the boost to 8 lbs. I put the 440s in and turned up the boost to 20 psi and thats when i could feel the power band felt slow and definitly too low. As for the fluids mixing i recently changed the oil and did not notice ( i am under the assumption it would be visibly thinned) anything out of the ordinary, I have not checked the coolant and I won't have access to the car untill this weekend.

HG = Head Gasket. HG Issue = Blown Head Gasket. Basicly I think your HG is blown. Although now that you are telling me that you ran 20psi on 440's I have a few more questions. How are you tuning the A/F ratio in this car? Do you have the proper assortment of guages? and if so which ones do you have? Were you running 20psi on pump gas? Were you pulling out any timing with the MSD? Do you know what detonation sounds like?, did you hear any? Basicly I need all the details of what was up when you raised the boost. I'm now thinking that you may have run it lean and blown some stuff up. Basicly if your HG is leaking it allows the explosion in the chamber to expang beyond it's intended path. If it's blown it could make the car run better or worse, you just don't know. It sounds like money is not a real issue for you though, am I correct? The rods you have in that motor are good/ better to some people than the eagles that you would get with the VT block. Give me some more details and I'll see if I can direct you further.

 

[hybridGS]

To start I have auto meter gauges, a/f , egt, boost, oil pressure, egt, fuel pressure, and no2 pressure. Well the 440's were given to me with the car, I installed them while the car was fuel tuned to the stockers so i was running 110psi of fuel at full boost. i installed a s afc at the same time. In either case the thing was immediately running so rich it barely idled so i tunned it enough so that i could drive it to the dyno. There we backed the fuel pressure to 50 psi at full boost and did alot of tuning with the afc ( i have a cartech fmu and it is to steep of a pressure slope to tune the larger injectors on a flat afc setting). In either case the the a/f ratio for the most part is 12 to 1 (using a wideband o2 at the dyno) as we gave up an making it exact since i was missing the power and he said whatever i had to do to fix it would require retuning the fuel map and there was no point in running up the dyno bill. I have a msd dis 2 which we set a 5 degree retard for ... i forget the boost incriment at which point i believe the timing is 21 to 23 (the msd uses it's own gm 3 bar map since there is a restrictor on the engines so the ecu doesn't read +pressure). I don't have a scanner to post the dyno read out, but it hit 230hp just before 5000 rpm as opposed to the 300hp that similar set ups hit at 3000 rpm even though it hit full boost at about 3500 rpm. They told me that it's at about 250hp now and I have not seen the read out. I don't know what detonation sounds like which is why I had the car tuned at the dyno so It would be set up correctly. Money is an issue which is why i want to get the car set up right once and for all so I don't have to keep throwing money at it to fix things that keep screwing up. The reason i am concidering the swap is because this will be the third rebuild on the block and if it doen't go right this time then I will be stuck with haveing to get a new bottom end either way, since i think i have a guy that can help me with the swap it could actually be cheaper to do so. I talked to the shop again yesterday and they said it blew the dip stik out of the car and that sound like alot of pressure getting by. he also told me that the 2300 dollar fix only included re ringing the pistons and honing the block so if they open it up and see that I have to go to larger pistons it will probably be cheaper for me to do my swap with a busher block then fix it ( which would be nice).

 

[Kirby]

I was not aware that busher made anything for the 420a r u sure that's not for the 4g63? So first things first here, you need to find out exactly what's wrong with the car. here is a link to my friend Corbin's page about compression tests. http://www.2gnt.com/www/corbin/comp.html
This is how you test to see what is going on. As I was telling you before if the HG is blown and allowing pressure into the crankcase it can also cause the dipstick problem. So instead of rebuilding the whole thing you could just replace the HG. If you did not turn up the boost till you were on a wideband then you should not have bad rings from any lean conditions. Do the compression test and see what you get, then we can talk about next steps. i guess what I am really saying is that I doubt it's the rings. Are there any metal shavings in the oil?

 

[hybridGS]

i will try to check this weekend when i get the car, thanks for the advise and i will keep you updated. The info I gave you only deals with my running it at high boost, the previous owner had also run it at 18pis with the 440 injectors and I don't have any knowledge of hes readings.

 

[Kirby]

I do understand that you have no knowledge of the previous owners deeds. Check the things I said and let me know what is going on before you have them take it apart.