shpcheung

Hi all, I was checking out an FD yesterday and got some questions..

1. body damage
what I have circled inside the green (attached pic). Does every FD has this dent? the mechanic who checked the car pointed this out to me and said this was due to an accident. Then i checked the other side of the car and saw the same dent. First FD i searched online has this dent.

The picture is actually from a How-to-coilover thread, i am borrowing them
https://www.rx7club.com/suspension-wheels-tires-brakes-20/%5Brx7-boutique%5D-beginners-tutorial-installing-coilovers-fd-909096/

2. compression test
ran a compression test from mazda also. (units = Kpa) rpm@235

1 2
measurment compen (250) measurment compen (250)
port 1 689 721.14 598 630.14
port 2 700 732.14 626 658.14
port 3 626 658.14 642 674.14
diff. port 74 44
diff no.1 / no. 2 28

i never noticed til now that mazda will do the compensation value automatically for the 250 rpm.

Diff no.1 / No. 2 = 28. seems to me they take the differences between the lowest from the front and rear (626 - 598) When comparing rotors, which numbers will u guys use? i was actually thinking (for e.g.) comparing the highest from front to lowest from rear, or taking averages.

btw. weak side seal in the front?

90,000 km original jdm engine, highflow cat and cat back, some mushroom intakes and an aftermarket SMIC.

thanks
shp

shpcheung

oh noes, the spacing didn't work out. sorry.

basically 4 numbers each chambers (port 1), go in the order of

front 235, front 250, rear 235, rear 250

anyway, sure u guys can figure that out.

Narfle

iTrader: (16)

Edit, wow when I quoted it I saw your intended formatting and it made way more sense. Yeah, it looks like you may need to freshen up the motor.

Dunno about the damage. Doesn't look out of the ordinary. If anything got that deep into the car there would be more signs of damage.

Captain_Panic

iTrader: (15)

1 kpa = 0.145 psid (pounds-force per square inch difference)

So it appears you are
Face 1 Front: 104.5psi @ 250
Face 2 Front: 106.4psi @ 250
Face 3 Front: 95.4psi @ 250

Face 1 Rear: 91.3psi @ 250
Face 2 Rear: 95.4psi @ 250
Face 3 Rear: 97.7psi @ 250

That's not too bad. Ideally you would be 105+ on all faces on both rotors. The rear tends to run a bit leaner, but not sure if that will cause compression to be lower over time...

I would say there is still some life left in this motor

hotmail6

Thats a lot better compression than one of mine. Did you do the compression test on a warm engine?

shpcheung

i think so.

they wouldn't let me watch them do it tho, i had to sit in the lounge.

but i specifically requested for warm engine temp and fully depressed accel pedal. printed out the workshop manual, highlighted those lines also well.

shpcheung

thank you dfoster154 for a more friendly summary and conversion.

yes, i am aware that these numbers aren't great but aren't super bad either.
just concern about that one particular low number in the front. Is that a sign of a weak side seal? 10 psi drop.

if u guys have time, check for that dent for me please? should be able to see the area clearly with a flashlight by turning the wheel all the way i think.

Captain_Panic

iTrader: (15)

I don't know if the 10psi difference at that level is signs of a bad side seal or not. it could potentially be some carbon build up. I am sure there are others with more experience than I on this. Perhaps a little steam clean could improve on it?