My first post! Compression test & oily spark plug question.

[robwclark]

Got an 06 SRT truck, and wondering if anyone knows what compression I should see. I am fixing to do a compression test because I have a few issues. Also the #1 spark plug has some oil on it, and looks fouled out. Anyone know what would be the most common cause of the oil in the #1 cyl? There is a paxton on the truck, but runs good. I work for Chrysler and picked this truck up as a repo a few months ago. The only mod I did was change the headers from Bassani shortys to a sweet set of full length American Racing Headers & Straight through mids & a custom Flowmaster exhaust. The truck puts down 620HP at the wheels on a dynojet before the Header/exhaust change. It has a few other mods too that came on the truck. Have no idea if it is the stock engine or not. The blower has been on the truck for at least 5000 miles that I have driven it. Thanks in advance for any help.

 

[tsmith3]

Sorry, I don't know what a the compression should check out at:dontknow: Someone will chime in soon on that.

Welcome to the forum:rock: Sounds like to you got a bada$$ truck. Oh, and post some pics

 

[rottenronnie]

160 - 170 range is normal for a stock engine, a few variables here... if it has a performance cam, it might be less...altitude is also a factor (the higher you are, the less it will be).

A leakdown test would be way more meaningful than a compression test. Hopefully, you will see no more than a 25% loss.

Oily plug could be from a bad valve guide or rings. Running with an oily cylinder isn't good. Oil vapors have a real low "octane" value and if it is detonating because of it or if your tune is off, or both, your stock cast piston may not last very long.

 

[Django]

Welcome to the asylum....

D

 

[Da1Chief]

Welcome and Hello, Glad that your truck found a loving owner that is interested in fixing it instead of using it up and tossing it away..

 

[TNVIPER]

welcome to the club....:rock: ......bad news is your truck is a time bomb if the bottom end has not been forged....you may already be seeing signs of that...

 

[Brat]

Welcome to the club,and what TNVIPER said is correct.

 

[pissant#420]

welcome

 

[1qksrt]

First off,Welcome to the best forum on the planet,
Second,I,m assuming that you changed the oil right off,I've seen a couple of engines,where the rings aligned and created blow by.Your best bet is to perform a leakdown test and take it from there,Also make sure that you do not have an injector leaking down.Could cause wash down to the cylinder walls,not to mention possible damage to the Paxton which is oil fed..

 

[robwclark]

160 - 170 range is normal for a stock engine, a few variables here... if it has a performance cam, it might be less...altitude is also a factor (the higher you are, the less it will be).

A leakdown test would be way more meaningful than a compression test. Hopefully, you will see no more than a 25% loss.

Oily plug could be from a bad valve guide or rings. Running with an oily cylinder isn't good. Oil vapors have a real low "octane" value and if it is detonating because of it or if your tune is off, or both, your stock cast piston may not last very long.

Thanks for all the replys people. I am 32 yrs old and been doing majors mods to my vehicles completely myself since I was 16. I am much more familiar with the LT1/LS1 cars, but I have also had 2 Vipers in the past. I have always done my own work when modifying cars, but for whatever reason I have never had to perform a leak down test. How exactly do I perform this and what exactly will I be looking for? I know if the bottom end is stock, it may just be getting weak. Thanks.

 

[rottenronnie]

Thanks for all the replys people. I am 32 yrs old and been doing majors mods to my vehicles completely myself since I was 16. I am much more familiar with the LT1/LS1 cars, but I have also had 2 Vipers in the past. I have always done my own work when modifying cars, but for whatever reason I have never had to perform a leak down test. How exactly do I perform this and what exactly will I be looking for? I know if the bottom end is stock, it may just be getting weak. Thanks.

Gotta love those LS1s. I am closely watching the progress on a 2000 SS Camaro (LS1) N.A. build.

Anyway a leakdown is quite simple to do- Here is one of many articles on the topic: http://www.carcraft.com/techarticles/116_0406_cylinder_leakdown_tester/index.html

And welcome to the forum- You'll find lots of good people and lots of help here.

Ronnie

 

[robwclark]

welcome to the club....:rock: ......bad news is your truck is a time bomb if the bottom end has not been forged....you may already be seeing signs of that...

TNViper, Yea I am guessing the bottom end is stock, but this is a repo, and I never got to speak to the owner. The only sign of the engine being built, is the manifold has been powdercoated black. I bet the owner was on this forum.

Who built your engine? Who makes pistons, rods, & a crank for 3rd gen viper engines & how much do they cost? Can these engines be stroked easily? What is the compression ratio of your new engine?

If the motor has issues(and I am pretty sure it does, I will be pulling it out and rebuilding it myself. At that time I will probably sell the Paxton in Favor of a Roe Roots blower. I will probably go with Shawn Roes heads he sells. Any idea what cam I will need, or a proven one you know that works?
Thanks

 

[TNVIPER]

TNViper, Yea I am guessing the bottom end is stock, but this is a repo, and I never got to speak to the owner. The only sign of the engine being built, is the manifold has been powdercoated black. I bet the owner was on this forum.

Who built your engine? Who makes pistons, rods, & a crank for 3rd gen viper engines & how much do they cost? Can these engines be stroked easily? What is the compression ratio of your new engine?

If the motor has issues(and I am pretty sure it does, I will be pulling it out and rebuilding it myself. At that time I will probably sell the Paxton in Favor of a Roe Roots blower. I will probably go with Shawn Roes heads he sells. Any idea what cam I will need, or a proven one you know that works?
Thanks

being a repo there is a good chance the former owner ran the piss out of it before giving it up........my build was done locally using a off the shelf Chevy parts....PM Stinker if you are wanting to build the bottom end...he has some great choices..

If I were you I would just keep the Paxton since you already have it...I like the Roe but wouldnt remove a Paxton that was already installed.....I have Roe's PP heads but have no idea how much, if any, they helped as far as performance since the SC and heads were installed at the same time.............

My advice is to do a lot of searching on this forum and ask questions before you do anything...dont get in a hurry or you will just make costly mistakes....and speaking of costly...just know ahead that the Viper engine is expensive to mod..2-4 times more costly than similiar mods to a Chevy or Ford......

 

[robwclark]

being a repo there is a good chance the former owner ran the piss out of it before giving it up........my build was done locally using a off the shelf Chevy parts....PM Stinker if you are wanting to build the bottom end...he has some great choices..

If I were you I would just keep the Paxton since you already have it...I like the Roe but wouldnt remove a Paxton that was already installed.....I have Roe's PP heads but have no idea how much, if any, they helped as far as performance since the SC and heads were installed at the same time.............

My advice is to do a lot of searching on this forum and ask questions before you do anything...dont get in a hurry or you will just make costly mistakes....and speaking of costly...just know ahead that the Viper engine is expensive to mod..2-4 times more costly than similiar mods to a Chevy or Ford......

I am taking every bit of your advice before you even give it. Thanks for the reply. I have already been doing all the serious considerations over the past 6months or so. I wont jump into anything quickly(I am too poor to). The prior owner had no idea it was getting repo'd because his wife told him she was making the payments, and wasnt. We completely surprised him on it. He never came to redeam the truck(catch payments up) and I didnt have the heart to call the guy up and ask what all he had done to it!

 

[robwclark]

Bump, Anyone have experience or seen oil in a cylinder & give me an educated guess as to where to look first? I am pretty knowledgable, but I can only make a guess....I need an educated guess. Anyone been down this road, and know where to look first? I know it can only be getting in there from the around the rings, through a gasket(head or intake) or through a valve. Anyone been there, done that? Looks like the engine is coming out for a rebuild. If the scenario turns out as just a valve problem and the oil getting in making the cylinder run bad and lose compression, then I just want to fix the head. I dont want to rebuild a motor that is still OK. Anyone???