Engine Dilemma

[RixR32]

Ok here's my situation.

Some people know my car was stolen near the end of last summer, so right now I'm in the process of making one good car from 2, so to speak.

The process is almost finished, but I've run into a dilemma.

Car # 1 is mint body, paint, interior, new clutch now..etc. Almost everything I needed I've scavenged from the 'donor' car (#2), or replaced with new parts as needed.
Compression on this car (engine #1) is 152/148/148/150/149/152
I'm fighting a hard start/idle problem with it though. Everything has been replaced but the injectors and fuel pump.

Car # 2 (donor) compression is 160/160/158/160/159/155.
Also looks to have had a whack of engine work....everything from coilpacks to injectors look brand new...timing belt done at 101k according to sticker. Odo says 121k. Starts, runs, idles perfect and pulls HARD.
Car 2 is very rough paint and interior wise however, has had a leaking sunroof and trunk also by the looks of things. Spare tire well rotten...etc.

Now.....should I just swap out the injectors/fuel pump from car #2 to finish #1, or should I swap in the entire engine.
Would that compression difference be noticeable enough through performance to warrant that kind of work, and time?
Other than this new start up/idle issue...car # 1 always ran perfect before..

This is the reason holding up my part-out....and summer fun

Thoughts?

Rick

[Snake556]

Hmmm... Personally I'd go for the full swap. Sounds like the engine in your donor car is running a lot better than #1 with better compression, and some more work done. Seems to me like it would be worth the extra work, since you know it's running great right now.

Let's see what the others have to say on this though.

[Skym]

Higher compression = good headgasket, etc. When compression drops it's valve seats, rings or headgasket. Most of the time it's headgasket. Also can gain more hp with more compression.

No 2 engine with injectors, fuel pump into No 1 car if No 2 engine has lower km (record km somewhere, so if you sell car you can inform new owner of km of engine).

[RixR32]

As far as I know, engine #1 has LOWER km. Sure doesn't seem like it now though.
How noticeable would the 10-ish PSI compression difference per cylinder be when driving, anybody have an idea? (All else being equal with engines running properly)

I was told yesterday by an experienced import mechanic that the headgasket looks to have been done recently on engine #2 (good call Skym)...and it's likely that the injectors/coilpacks/timing belt etc.. and what have you was just done all at the same time. Water pump does NOT look new however...

Edit: Was also told 10 psi would barely be noticeable and to just up the boost a couple PSI to compensate? Kinda skeptical on that....I know 10psi is a BIG difference on the turbo side of things....
Also..neither engine uses any oil or coolant...and no mixing of them either.

[Skym]

Higher compression = more hp. I think you are right, probably not much difference if boost was increased a little bit more.

When they skim head it evens out the squish area's in dome parts (where valves are located) of head (they measure each dome with fluid, etc before skimming head), so compression becomes more even between cylinders. It's common practice on any high performance engine, including V8's. I gather that's what the mechanic you showed it to thought when he saw the compression figures.

From what I understand the even compression helps with tuning engine (even amounts of air, fuel in each cylinder), so I would think it's the best route.

If have to do waterpump, do front cam, crank seals at same time. Those seals tend to leak when engne gets older.

[RixR32]

In the middle of swapping now. Thought I might as well go for it.

Then I'll be parting out the remaining car and misc parts..

Rick

[RixR32]

Wow thats a project and a half.
Finished up late tonite...now a gotta get up for work at 5 am.

But.....

Runs better than it ever has..aside for some weird clunking from the rear end. Oh well I knew it was on it's way out. Diff swap coming soon I guess...

Woohoo!

[89Baysideblue]

i have this same wierd clunk in the rear end almost as if somethings loose and banging around from time to time? never did pay to much attention to it but now come to think of it....hmmm? i wonder?

[RixR32]

i have this same wierd clunk in the rear end almost as if somethings loose and banging around from time to time? never did pay to much attention to it but now come to think of it....hmmm? i wonder?

Diff.

Or hanger bearing...try that first it's only $90 from Adam or Daryl.
I replaced mine so I know it's not that.
Feels like play somewhere back there...most noticeable when letting clutch out going into reverse then back forward..if that makes sense.
When the torque changes direction..

Rick