New KA24 won't pull top gears

FINALLY hit the test day at Sebring on Friday to break-in our new motor. Morning sessions were 4500RPM limit; ran fine, pulled easily, felt like there was plenty more.
Afternoon sessions, bumping the revs up, my co-driver said he felt a surge mid-way through, and brought it straight in. Next session I go out, and it'll barely pull 6kRPM in 4th, and really struggles to make headway in 5th.
Now, I know this shouldn't be the ECU fuel-shutoff, because we have a modded ECU (speed-limiter only at this point); besides, we've hit the limiter before, and this was just a "no power" situation.
However, the car now has 4.36 gears, so I don't know how that affects the ECU.
At this point, we're gonna do a compression check and leak down, check the fuel psi, and try to figure out whether or not the cam is timed correctly. We set the ignition timing to 15 or 18 degrees (co-driver did that, so I'm not sure), but we've got to check that again to see where we ended up. I'm about to get on the phone with JWT and plop down a chunk of change with them [planned to do that anyways, just didn't have time before this test day].
The motor has the over-sized pistons, but is otherwise 100% stock, with a Hotshot header and open 2.5" pipe. We noticed a small leak developing at one of the exhaust welds, but I doubt that would restrict top-end power this much.
If anybody has any other ideas, I'm listening. My fear is I didn't get the cam timed properly. And that has me freaked out because of Dave's(dpc) report of blowing his up because the cam chain was off by one tooth.
On a positive note: the Ground Control/West Tek setup is incredible! The car outbrakes/outhandles everything in ITA (IMHO). I even had the privelege of sticking with a GT1 Camaro through Turn 1, and then almost bumped him in the carousel....hehe Realistically, I don't think he could put the power down because of the bumps in Turn 1. And yes, he left me sucking wind exiting the carousel...but it was still fun.

Michael
[email protected]

Michael, check your timing chain, befor mind blew I had great low end and midrange and no top end above 5200rpm. On the second engine we found out that the chain guide that is suppose to move was frozen in place causing the chain to skip around, You can pull the engine cover off in the car( I think)But I would look. West Tek is the best, Dave call me if you want 518-792-4986

Mike...
we missed you at Sebring..we came in about 6:30 friday...Call me if you want..Lets try to figure this one out...

Jim
407.389.1707

Quote:

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Originally posted by dpc:
Michael, check your timing chain, befor mind blew I had great low end and midrange and no top end above 5200rpm. On the second engine we found out that the chain guide that is suppose to move was frozen in place causing the chain to skip around, You can pull the engine cover off in the car( I think)But I would look. West Tek is the best, Dave call me if you want 518-792-4986

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Apparently there was a TSB regarding the chain guide and the tensioner.


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George Roffe
Houston, TX
84 944 ITS car under construction
92 ITS Sentra SE-R occasionally borrowed
http://www.nissport.com

Thanks guys, I really appreciate the assistance.
Jim, we bailed Friday right at 5pm. Neither one of us could stay the weekend. I'm looking at running the Regional on Jan 4-5 during the Winter Nationals. And on Dec 21 there's a Performance Drivers Club event at Sebring that we're shooting to be at to shake this puppy down again.
This motor was supposed to be "ready to go"; especially after waiting 6mos for it to be built. Unfortunately, the builder didn't notice the front cover had already been worn through by the timing chain, allowing water to be pumped directly into the oil pan.
My first attempt to pull the front cover resulted in ruining both the head gasket AND an oil pan gasket. So I'm really not looking forward to that effort again. And the "easy" way is to pull the head...yuck.
But after about 20qts of oil and a bunch of filters, it runs...quietly :-) And shows 60psi-oil, 15psi-water.
Dave you might be on to something. If the water intrusion has messed up the lubrication of the chain guides/slides, then maybe the chain has jumped.
I think we're gonna take the car to Don Ahren's in Gainesville, and see if he'll do the tests and check the chain; he built our Quaife/gears, maybe he'll go easy on us...hehe Neither my co-owner/driver nor myself have the time right now, especially when we're trying to get back by Dec. 21.
One of these days I'll figure out how to write shorter posts....
Michael
[email protected]

PS: George, I think they only issued the TSB for the DOHC motors, which called for removing an upper guide. However, the factory replacement chain guides for the SOHC were made out of metal, instead of plastic like the originals. They usually didn't fail until 60k+ miles.