: compression...need advice
04-16-2008, 09:48 PM
my car has been at mcnews for 3 weeks now for a clutch/fly lsd and tune. today they got it on the dyno with the 10psi pulley and it only made 5 more hp than the 8psi did 6 months ago...so they did a compression test and it showed 105 in 2 cylinders and 115 on the other 2. i was going to go for pistons and rods but there booked for the next month, and i need the car, they say its safe to drive, just dont push it. what do you guys think?
also what is the compression of the svt motor and where should i be at with 68k miles
04-16-2008, 09:51 PM
You read my responce in the other thread.....
04-16-2008, 10:17 PM
You read my responce in the other thread.....
i did read it, mabe someone has similar setup, just looking for a few opinions before i go blow 3k on a bottom end.
04-16-2008, 11:06 PM
Did you see the dyno , did the 5 come from peak HP , what did it do over all in other places other then peek HP
Not enough info
04-17-2008, 06:22 AM
they just told me they did 2 runs and it did not make any power, so they did the test. i will call them back and ask, and possibly have them email me the dyno so i can post it up here.
04-17-2008, 09:33 PM
so does anyone know what the compression of a brand new stock motor should be.
04-17-2008, 09:51 PM
~ 140 psi
though your compression numbers are within 10% of each other, which is what it's supposed to be at least. it does seem low, but evenly across the range.
04-17-2008, 10:00 PM
140 psi... so im about 30psi low. well i guess the smart thing would be to save up and do the bottom end.
04-18-2008, 12:30 AM
From WD40 in one older topic :
Don't forget, we have hotter cams than the base model, with more valve overlap.
That overlap will actually drop compression when doing a test.
I don't doubt an SVTF engine will show lower numbers than the base model because of that.
In fact, I'll bet the numbers come out to between 120-140 max.
Don't be so concerned with getting high numbers.
It's consistency you're looking for.
All cylinders should be within +/- 10% of each other.
^^^That's what you should be looking for.
and sometimes people seeind low # because of that overlap, or wrong VTC.......
04-18-2008, 03:37 AM
lol so you've been the one holding up my upgrades. Well I don't mind at all, doing it right takes time.
04-18-2008, 06:21 AM
all cylinders are with in 10% with each other. so that means the compression is ok ? but its low enough that im loosing power. thats cant be rite.
04-18-2008, 04:15 PM
what's the pulley size u had there before and now ? do you have a boost gauge ?did they see over 10PSI at redline ? No belt slip ? Ask for dyno pic as tom requested
04-18-2008, 08:28 PM
i had the 8 psi pulley which made 9psi peak and made 253 whp. yes i have a boost guage. the 10psi pulley only put down 5 more hp. ray thought it should have made more like 275ish so he checked the plugs and did the compression test.
i did not ask what the peak psi was, or if the belt was slipping, nor did the tell me.
i asked for the dyno to be emailed to me but i never got it. ill get a hard copy tomorrow. and ill ask all these questions.
thanks for the advice and info so far. ill be posting the dyno asap
04-18-2008, 08:52 PM
here is the old 8psi dyno
04-20-2008, 01:10 PM
ok got the car back, it seems to run good.
here is the dyno. the run with 5 more TQ is the is with the 10 psi pulley which peaked at 11 psi. and new belt was put on as well.
the other run is the old dyno with the 8psi.
04-20-2008, 04:21 PM
Hey i was there when you picked up your car I was they guy dropping off the turboed svt.
04-20-2008, 08:02 PM
were you really... lol. what are you having them do?
04-20-2008, 08:29 PM
they are tuning my car, i was the guy talking to ray when you got and left
04-20-2008, 09:39 PM
ooo ok so thats who you were. well i hope ray can put down some good numbers for you. let me know how you make out when you get the car back.
04-21-2008, 02:38 AM
Hunh, there's a lot of us (3 is a lot!) getting or just work done at McNew's.
That's cool to know that they are still regularly getting FF business.
04-21-2008, 08:05 PM
yup i like the work they do, and there really the only place that i trust.....3 hours.
04-24-2008, 05:30 PM
btw, ken, hows the LSD doing for you?
One of the guys on the phone told me they figured it out for your car and they were going to do the same setup for me. I figured it meant getting the parts that don't come shipped with the LSD.
04-24-2008, 08:26 PM
the lsd is nice, you get better traction through the corners, both wheels hook when you launch it, and mcnews had to do some searching for the seals and bearings, but they got it done.