Car has been feeling sluggish latley, did a comp. Test. Car has a 97itr head, skunk2 flat faced valves, 12:1 compression, 11:8:1 pistons. Results were as follows cyl. 1 -190, cyl. 2 -185, cyl. 3- 187, cyl. 4 -180. Strange thing is the first compression tester i used read 200 in cyl 1 and 2. Then the tester broke so i couldnt finish and had to re do it with the new tester. Car was warmed up, inj fuse removed, distributer unpluged and throttle opened up 100%. Seem like okay results? Also the spark plugs seemed to have a pretty white/ light gray tip. Thanks guys!

 

Btw car is dyno tuned and made 187whp, just doesnt seem to run like it used to

 

12:1 CR should be making more than 187whp. Stock ITR with bolt-ons makes about that, right? You should be seeing ~250psi.

 

I understand, i was just under the impression not to worry so much about the number as long as they are close to each other, which for the most part they are.

 

that is low it should be about 260-275ish depending on the cams. my R witch has wiseco +5cc pistons and a gsr head blows 270psi on ctr cams when the motor was cc the comp came out to like 11.9-1 so u should have simler comp as me

 

Throttle body was opend while cranking

 

The plugs were very white , maybe something fuel related? No cel. Just seems slow sluggish,

 

Compression is low
Low compression low power dawg

 

The motor setup has probley 20,xxx miles on it. how could every cylinder loose compression? Wouldnt it just be one or two, all the numbers are consistant

 

wideband in the car? AFR?

 

doesnt white plugs means signs of detanation?

 

No , I do have a neptune tunerveiw that read's afr but it always reads 17.5 which im sure is not correct, I dont think the tunerveiw is getting a accurate reading. here is a picture of the plugs today when I took them out for the compression test. Also I should add that the car doesnt feel awful slow, It still rips, It just doesnt seem to pull like it used too.

 

If your using the stock 02 sensor it only reads 14:7 a\f
Wide band use a 0-5v out put= 10- 20 a\f

 

first thing i though of was cam timing. what cams are you running and are they dialed in? cam gear slip?

and did you ever do a compression test when the engine was new? i figure you'd have mentioned it if you had.

 

No, never did a compression test before, they are 97 itr cams, the whole head is 97 itr

 

well.. then that likely isn't it.

strange.

 

I agree, i guess i will check timing, do a leak down test and see whats up, its got a slight miss to it also sometimes, it all started one day, very weird

 

I agree, it seems comp. is low, stock B18C5 is 270 psi, [standard] 140 psi minimum with a max diff. of 28 psi between cylinders.

Your well within the 28 psi but low, even at 190 psi.

I assume it was a dry compression test, if so, redo the dry test and record the results then do a wet compression test and compare, let us know what you find. 94

 

I will redo tomorrow and let you guys know. It just seems to me since the numbers are so consistant that everything is fine, i would of thought if there was a issue it would be low in one or 2 cylinders, this car uses NO oil at all, doesnt smoke at all either

 

Maybe the compression tester was bad. First tester i used was reading 200psi

 

that's a difference of 10psi.. i'd expect two thermometers to be off in similar fashion.

the whole premise is that you should be like 50+ psi higher than where you are.

in for tomorrow

 

Those plugs look pretty good too, FYI. Maybe just a bit rich.

 

white spark plug is lean but granted thats idle

try adding 1% fuel across the map and see if it run better

 

I will have leakdown test results by friday evening guys

 

Hey guy's took the car to my shop I go to and they compression tested it at 240Psi the whole way across, I guess both testers I used were faulty !