compression tested today: uh oh.

[fiznat]

right so I always kinda assumed my compression was good on my 155,000 mile KA24DE because it runs so well and puts down some pretty decent feeling power, but it turns out today that those were pretty bad assumptions.

I bought a compression tester kinda on impulse and decided why not test the engine before I actually go out and purchace the turbo... well, here's the results:

1. 125 ouch.2. 1403. 1504. 165

I poured a capful of oil into the #1 and got a solid 165 out of it. crap. so... jeez... I guess I'm left with very few options right now. Turboing the thing on stock internals, as was my plan, certanly isnt feasable anymore... so this means I'm going to have to buy at the very least new rings - probably pistons - and pay to have them fitted and whatnot. While I'm in there I guess the assumption is why not just do rods at the same time, and ARP head studs, and this and that and etc etc etc.... This is getting really frustrating here, because I thought I was finally on a roll with this KA-T project and I find out I'm actually stuck at square one.

What do you guys think I should do? I mean... I guess my only options are 1. build the engine and turbo it or 2. give up and scrap the whole idea... unless you guys can think of something else, I'd really appreciate some words of encouragement or something... Sigh.

[fiznat]

I just read through the instructions again on compression testing and noticed that I was supposed to hold the accelerator down to "keep the throttle wide open." I didnt do this at all... do you guys think that could have affected my results?

[TachyonS14]

I'm not sure about your question, but if worse comes to worse maybe find a low mileage KA and test it to make sure? Then strap on a turbo? KA's are a dime a dozen. Hope all goes well.

[TrunkMonkey]

... do you guys think that could have affected my results?

most definitely. even though you didn't do it this way, your numbers still should have been consistent. redo the compression test the corrrect way, and if the motor is shot, i'd rebuild it. i've never been a fan of swapping in used motors.

-demetrius

[Altiman94]

if you're gonna go turbo I would probably rebuilt what you have with stronger internals and lower compression pistons. Do it now so you dont have to later.

[PalmerWMD]

Is this compression dry? Or cold?Hot + wet will be more accurate to what you reall have 165 on your "weakest" is pretty solid.

Fred..

[fiznat]

Well I did the test again, this time holding the throttle down-- no changes at all. Pretty much exactly the same numbers.

The engine was warm- I warmed it up before testing (both times). I'm not sure what you mean by "dry." I only put oil into #1 and that bumped it from 125 to 165: about equal to my best cyl (#4).

I spent the weekend calling machine shops and leaving messages, tryin to figure out how much it's gonna cost me for the block work I'm sure I'll need now. I suppose this could turn out to be for the best though. I mean, at least now I can boost to ~15 psi without having to bite my nails worrying about blowing the ring lands on the slightest mistake...

[stillmatic]

This is what I would do. Put the turbo project on hold and rebuild the engine. Get as close to 200HP with an N/A setup. Then when you have the money, you can go turbo or just leave the car as it is.

[Nathan]

Trying to make 200hp NA and then switch to a turbo is a huge waste of money though, not to mention the engines should be built differently to serve those functions. I say replace the pistons, bore and hone the block, replace the bearings, maybe deck the block if it needs it, have it re-assembled and go on with the turbo kit.

[fiznat]

yeah but a NA build would require different CR pistons. I want 8.5:1 for turbo, I might even bump it HIGHER than stock for NA.. they're different buildups, I cant really go halfway and stop with this I dont think. ...also headers would be a waste, exhaust would be different, etc, etc, etc...

EDIT: what nathan said

thanks for the advice though

[stillmatic]

Hehe, I was just speaking out of boredom. I always thought it'd be better to go turbo with a mild N/A tune, but now I know better. I'm in the same boat as you. I'm currently saving up for a cheap turbo setup, somewhere around $1500-$2000. My car has 165,000 miles and I haven't even done a compression/leakdown test. I wanna do what slos13 did and turbo a high mileage 240, then do a rebuild when the time comes.

[WDRacing]

Remove engine then the rods and pistons. Inspect cylinder walls for scratches, if its in decent shape use a ball hone and remove the old ring glaze. Make sure to remove the oil squirters first. A ball hone is only like 60 bucks. Get your stock rods magnafluxed and reshotpeened with a good polish. Use a new set of forged pistons and rings. Change your rod bearings as well. I'd stay with stock rods unless your going for over 400hp. But thats just me. You could always just buy forgies. Depends on money...

WD

[fiznat]

yeah you're right WD... I think I'm just gonna bite the bullet and buy a nice set of 8.5:1 Ross pistons with rings, go with the stock rods, and have the block nicely balanced, bored, and blueprinted.

I'll have one nasty KA-T after that, though

[rco8786]

This is what I would do. Put the turbo project on hold and rebuild the engine. Get as close to 200HP with an N/A setup. Then when you have the money, you can go turbo or just leave the car as it is.

That's the worst idea I've ever heard, he would have to undo half the stuff he did to build NA b4 he went FI.

[fiznat]

relax rco, he knows already-- read his 2nd post.

[WDRacing]

Sounds like a good plan...If you get everything balanced. Get the crank, rods, pistons, flywheel and crank pulley all done together. Then you shoiuld be set. Just keep the RPM's under 7200 or so and you'll be fine with the stock rods.

WD

[andrave]

I have a question with balancing, if you have the stock flywheel and build your motor and have the bottom end balanced, and then later you get a lightweight flywheel.. would that mess stuff up?

[TrunkMonkey]

I have a question with balancing, if you have the stock flywheel and build your motor and have the bottom end balanced, and then later you get a lightweight flywheel.. would that mess stuff up?

no.

-demetrius

[Nathan]

Hopefully, the new flywheel would be pretty well balanced, as well as the old stock flywheel. In that case, it wouldn't affect the overall balance.

[andrave]

yeah I was figuring that was the case... if that is the case, why balance with the flywheel on the assembly?

[LoserbabyS13]

Fiznat: Did you unplug your injectors before running the comp test? This needs to be done as fuel being sprayed but not burned will wash away the oil in the cylinders and cause the numbers to be lower as you go down the line.

[fiznat]

I didnt unplug the injectors, but I did pull the fuel pump fuse and ran the engine for a few seconds till it ran out of fuel... I think that should do the same thing. Besides, my numbers got HIGHER as I went on, not lower. oh well, thanks for the info though!