Does anyone know the stock compression # in psi for the type R?

 

250 should be around right.


[Modified by FAST94GSR, 2:40 PM 8/22/2001]

 

Factory New I believe is 260. I tested mine and got 230 (3) and 235. The wear limit was something ridiculously low like 150. All the tolerances are in the Helm's and I'm not 100% on them, but the values I gave are what my car tested a few months ago (98 ITR - ~42K then).

 

I tested my compression last night:
203,203,203,206 psi (dry)

Motor has about 50,000km on it. It is also running with stock internals. I did drop some oil into the pistons to do a "wet" test but my results did not change.

Can others post there results so that we can see what the spread is like?

Regards,

 

Stock compression should be in the 200psi ball park. I have a MUGEN High compression gasket on my R and I am getting 245 - 255 psi.

 

Thanks... I have seen simular numbers to mine posted for GSR motors. What is the difference in CR?

Mr. Animal, did you to a compression test before the gasket when in?

Regards,

 

I THINK ITS AROUD 230/235PSI

 

mines 190 across, a little low i think but within specs. i check it periodicly, and it hasnt changed at all so i guess im ok for now.

 

I don't know where you guys are getting 250psi on a stock R.

I got a GSR with US ITR pistons and brand new (Fresh rebuild) with .010 milled and a GSR head gasket yields me 235 across the board.

I think 200-215 is normal for a R in stock form.

Hell stock GSR's put out 190-200

 

Yes, I did it was 200 - 205 STOCK 2001 Engine. After Gasket 245 - 255.

 

Thanks guys! I feel much better now!

One thing I'm going look into is my compression tester. It uses an adapter that screws into the base of it. It is this addapter that screws into the plug socket. I measured the internal volume of this addapter to be 5ml which represents a fair percentage of the final compressed volume inside the piston (i.e. the addapter is effectively reducing my CR during the test). I believe this "extra" volume is effecting my numbers by about 10%. I'm going to fill in this volume with some hi-temp epoxy and run my tests again. My point here is that I believe that numbers might very depending on tester design. If I find that my modified adapter increases my readings significantly then I will have proven this.

Thanks again guys for your input! I'll let you know what I find!

Regards,

 

The actual exact number is not important....all ITR'S are going to be a little over 200...but the main thing to make you happy is that all the numbers are within about 5% of each other...that means your BEAST is healthy.

Jeff

 

Maybe it's my motor? Maybe it's the Comp. tester I used but when my car was sick....

(bent valves in cylinder number 4)

it yielded numbers (from cyl. 1-4) 180, 183, 185, 80(!)

I have sinced fixed it and have also put in a 2 layer h.gasket and now the numbers are
200,200,200,205.

we also did a leakdown test and the numbers are within 2% of eachother on the gauges....

I'm not sure if there is just something wrong with my motor or the gauges we use....I believe the comp tester was a bluepoint and the leakdown tester was a Snap-On.

The car still ran a 14.378 back in May all things stock except for the Spoon ex.mani (stock downpipe)

Totally confused here especially when peeps are posting as high as 245 or so...when my friend's old motor with PR3 pistons in a GS-R head did 255 "only"

 

DRY TEST 99 ITR with 45000km STOCK MOTOR 225/130/230/225, after rebuit two bad valves and take out 0.75 of head,now 245 all 4..
DRY TEST 97 ITR with 65000km STOCK MOTOR 215/220/210/215,WET TEST 270 all 4..

 

In my Gsr I have 220 all around with a .043 gasket and .030 milled head, people have told me that my comp ratio should be around an Itr's at 10.5-6. So wouldnt an Itr psi be around 220? I dont know, different people say different things....

 

Just thought I would update you guys on my results after modifying my compression tester. The tester that I was using used a screw on adapter that was placed between the tester valve and the engine head. This adapter had a 5ml internal volume (didn't seem like much but wait) which in theory was lowering my compression ratio by ~10%. So I decided to fill the adapter with a metal bonding epoxy and then drill out a small hole so that the adapter could still pass the compressed gas to the tester. The new volume was likely much less then 1ml.

Results: well my numbers went up predictably by about 20psi, putting all of them in the low 220s now, still very consistent across the board but now a little higher.

My point is this, as has been stated before; I don't think it is important to look at the absolute values too much because they cannot be trusted entirely. My experience shows that simple changes in the test equipment will yield different results. What is important is that the numbers are all close. If they are then one can assume that there are no major leaks as they would most likely not be present on all cylinders to the same degree.

Hope this shed some light.

Regards,