Alright so I have an engine that runs great until 5500 RPM's.

It is breaking up and loosing power after 5500. At first I thougt it was ignition related, but a brand new distributor, plugs, and wires did nothing. I then started thinking it was compression related so I did a compression check 240, 240, 240, 240. Now I am stumped, but I decided to give it a leakedown test since I just got a new tester. The leakdown test showed 15%, 15%, 100%, 45%. I figured they were going to be a little high since it is a brand new engine and maybe has 20 miles on it. now in #3 and 4 I can't tell where the leak is coming from, but why wouldn't a 100% leakage show up in a compression test, and why does the car run great under 6000 rpm's.


So I pulled the motor apart thinking I F@#$ up two pistons, but I was wrong they both look perfect and not a scratch on any of the walls. So I go to the head and check every valve to see if they were bent , but every one was perfect. I had the head pressure checked and it turned out perfect. I then put a strait edge on the block and it was perfect stepped deck was consistent all around.

What can I be overlooking. On the dyno it showed 250hp on 8psi right before it starts to break up and loose power. WHAT COULD I BE MISSING!

her are some FAQ about the motor.

RS machine sleeved block
B18B1
B16A2 head supertech valve-train
JE pistons and eagle rods
ARP head-studs

Also there was no oil in my coolant and no water in my oil. Car did not overheat and ran like a champ on the street. Anybody have any ideas.

Sorry I put this in two forums but i figure alot of the people in the drag forum have experiance with built motors.

 

What engine management are you running? What size injectors do you have? Are they low or high impedence if they are low are you running a resistor box?

 

im running hondata s200 with MSD 96lb injectors with resistor box. also the air fuel was 11.8 straight across.

 

What is the gap on your spark plugs and what kind are you using?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Rtype16 &raquo;</TD></TR><TR><TD CLASS="quote">What is the gap on your spark plugs and what kind are you using?</TD></TR></TABLE>

i was going to ask the same thing, i had a similiar problem last year, andthis was the culprit..

 

I have tried NGK heat range 8's and 7's with .025 gap and ZEX cold plugs....can't gap them.

 

whoops i din't actually look at the leakdown numbers. A compression check is good, but a leak down is another good way to find out if a motor is messed up. Can you tell if it is coming from the exhaust, intake, bubbles in the radiator or from the valve cover.

 

???

 

well i just put it back together...everything was to spec so wish me luck.