dylan_lawson

Ok let me start that with the weather starting to make a turn for the better I decided to do a couple pulls and log them for virtual dyno. I did a 3rd gear pull and a 4th gear pull letting it cool down in between, both were done on same road about 15 mins apart. So here’s where my question begins, in 3rd gear it made the same as the last pull I did right around 510. So I let it cool down the did a 4th gear pull and it feels lazy and only made 460, the logs look identical except 4th spooled faster just like it always does. Afr’s and boost were identical and timing is spot on. I did do a 3rd gear right after no cool down and it made 500 with it being hot. Could this be sign of a clutch slip like it just can’t hold the power with the faster speeds? Open to any suggestions to inspect and all help is appreciated thanks

LetsGetThisDone

iTrader: (1)

If you don't adjust the gear ratio I'm virtual Dyno, it will make less power.

Clutch slip is the rpm jumping up, and then back down when the clutch grabs. Doesn't sound like you're clutch is slipping.

kaj

iTrader: (60)

If the clutch were slipping, RPM would be going up without the car going faster. Pretty much the opposite of what you are experiencing.

dylan_lawson

Ok that makes sense but I’ve used virtual dyno like this before and it made around same power that’s why I ask. I do switch the gears on the car and it’s stock driveline so I just use the standard gear ratios provided

dylan_lawson

I also forgot to mention that I changed wheels and tires over the winter and I messed up on sizing and got a smaller diameter tire. I have adjusted that in vd but with it being a smaller tire at high speeds could that effect the top end throwing off the numbers?

dylan_lawson

Just did a compression test and cylinder 3 and 4 have no compression. If I put a spark plug in either then they both have right at 180. I’m going to do a leak down tomorrow. I’ve searched for a while but I remember reading somewhere that if it’s 2 cylinders beside each other then it could be head gasket or cracked cylinder wall if anybody can confirm that it would be greatly appreciated thank

Apex Hunter

iTrader: (1)

How are you checking compression with a spark plug installed?

Let us know how the leak down goes.

kaj

iTrader: (60)

Most likely checking one cylinder with a plug in the other in question, then vise versa.

dylan_lawson

Yea I had all the plugs out went through all of them. On 3 and 4 I had 0 psi, so with tester still in cylinder 4 I put a spark plug in cylinder 3 and retested 4 and had perfect compression of 183. Did a leak down and I am leaking between cylinders. Haven’t had time to pull head yet to determine where but the last time I had head off back when it was only 350 whp, I had a slight burn between the cylinders but I was changing gasket anyway so didn’t think too much of it, so I assume it’s a slight warp in the head right there. Got the new gasket and head studs on order just waiting for them to get here and then I’ll take head to get re decked and put it back together but will keep you guys posted

Apex Hunter

iTrader: (1)

Ahh, makes sense now. Yeah good luck!

dylan_lawson

Incase anybody stumbles across this, it ended up being a burnt head gasket. Changed it out 176-180 across the board and now she’s ripping again