Digi7ech

iTrader: (1)

I'm gonna get a Jspec and the numbers sound pretty good.

It had 85 psi on front and 95 on back.

I know 95 is great but the 85 is borderline right?

I saw some other thread about how low comp engines put out lower numbers but this is around what my GTU was doing.

beefhole

iTrader: (29)

Those sound pretty low.

ZachSpazz

90 PSI is low. Good compression is anywhere from 110-120 PSI.

Look elsewhere, or consider a rebuild.

Digi7ech

iTrader: (1)

I've heard 95 isn't bad.
Especially since I'm getting a S4 Jspec.

I'm doing a NA-TII conversion so I need the long block before I can rebuild.
I also don't have the money right now to rebuild. I plan to get it rebuilt in around 2-3 months when I will have money again. You think these numbers would last for atleast 2-3 months.

13bpower

No, that is borderline already dead. I wouldnt install it, or even buy it unless it was just as a core for a rebuild. It's probably worth $300 (longblock) as a core. My TII is at 100 100 and I would rebuild it right now if I had the time and money. I have to wait till I graduate this summer though.

steve

rxseven

95psi is *ok* for the s4 but anything less than 85 is going to be troublesome. Not worth it unless you are getting it for a core price.

Digi7ech

iTrader: (1)

There are no cores in Arizona so I have to go to some outside company. It is going to be $1100 for it.

I know it's a Jspec but I can't afford another $1500 on top of that right now.

StealthGXL

iTrader: (1)

I would just keep looking. $1100 sounds a little steep for a engine with compression like that. Even for a J-Spec. It's going to cost you more money anyways if you buy that engine and rebuild it, than if you just bought an engine with good compression for some more money

13bpower

Keep looking, I ran across some guy selling J-specs (with tranny still attached) for $650 once. I wasen't even looking.
steve

Digi7ech

iTrader: (1)

I have to get my car running by mid December at the latest. It was my daily driver and right now I'm driving my 88 SE but this thing feels like it will die any day now and I work 32 miles from home.

Also like I stated above. If I could buy a Long block rebuilt engine I would do it in a heart beat but I am doing a TII conversion and need ALL the parts.

SDrotary

i can get you a core if that's what you need.$450.00 for a Series4 and $550.00 for a series 5. chris

13bpower

Do what you have to do. Just keep in mind that an engine with that compression would be no better off than your dying SE.

Digi7ech

iTrader: (1)

I need longblock cause I don't have the engine in my car.(Need Manifold/turbo/IC/injectors/etc....)

Also a little clarification on the compression results.
Will a NA high compression engine give higher numbers than the low compression 8.5 TII engine?

Or is this completely irrelevent? My GTU pulled high 80's/low 90's and it's NA.(Months before it blew a coolant seal)

SDrotary

is'nt 120 a little high for a used motor. they rate good as any where between 80-85psi.

Digi7ech

iTrader: (1)

I have heard 120 is straight from the factory and 90's are common.
That's why the responses have confused me.

SDrotary

yea 120 psi is very low mile used motor, most we get are around 90-100 psi.

bcty

120 -130 from factory.. below 90 send er back.. you can get a good j-spec around 100=110 compression.. just look harder

13bpower

I would say below 90 is low. FACTORY is 125, a good rebuild will yield 110-115.

A turbo motor can turn 85 compression into 0 much faster than a N/A motor.

SDrotary

I have looked for a while for a good source of jdm motors, if it's so easy show me one place that has them in stock with 110psi.

Ni5mo180SX

The engine I purchased did 120psi on both housings during compression.

Id pass on anything under 100psi.

maxrotor

85-90 is a good compression for a used motor. Most places post WET compression numbers and say 110PSI when in reality if they would have done a normal test it would be lower. Also most people use a non Mazda comp tester and think they can do it that way when it can get close but never be correct.

Turblown

iTrader: (12)

Could be an innacurate test. My buddies motor had 85psi when we did a test, then we held the throttle wide open. We then got 105psi ....

88IntegraLS

I'm sure it would run and probaby run fine, but there is still 10psi difference between rotors. My S4 NA engine had 90 on both and it ran great. I haven't tested it since I rebuilt because I don't care. It has been running better than before and I've got better things to measure!

marcus219

My s4 n/a engine ran solid on 90psi, both rotors for along time....the diff. in the #'s on the j-spec your lookin' is kinda a red flag, id keep looking if you could though. From my experience, I think 90psi would run just fine for you until you have money to rebuild, unless somethings else causes engine failure (ping ping, etc... )

FD3S_wanted

iTrader: (5)

My jspec TII has 95 psi on both rotors. Should I rebuilt it ? It's stripped to short block right now.