DOHCarp

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.

DOHCarp

Bump for the night

DC2R714

What fuel management you running. I had the same problem when I was running really lean.

Muckman

iTrader: (2)

You mentioned nothing about the tune. It sounds like tune related not mechanical related.

BEV@GSCMotorsports

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Muckman &raquo;</TD></TR><TR><TD CLASS="quote">You mentioned nothing about the tune. It sounds like tune related not mechanical related.</TD></TR></TABLE>

I agree. Be sure to check your plug gap, it's possible you're blowing out the spark if the gap is opened up to much... and like he said before keep and eye on your A/F ratio... Hope that helps a little.

If i think of anything else i'll let you know. Keep us posted!

Good Luck

EKB18BPR3

im guessing u got stock fuel pump...stock fuel pump can handle so much then it levels off...or even dips at high boost.

DOHCarp

I have hondata s200 with a good tune, 1000 injectors, and I decressed my plug gap then after that didn't work I put in ZEX plugs. I do have a walbro intank.


ALright if everybody thinks it is the tune I am showing an 11.8 A/F, but what about the leakdown number?

DC2R714

There is definitely something up with the leakdown. When you tuned are you getting crazy blowby?

DOHCarp

not much blow by at all. Just the usual on a brand new engine. Also I just pulled the valves and all of them were up to spec...I thougt maybe one of them could have been bent when I gave it to the guy to do the head work, but they are all perfect.

underpressure02

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DOHCarp &raquo;</TD></TR><TR><TD CLASS="quote">I have hondata s200 with a good tune, 1000 injectors, and I decressed my plug gap then after that didn't work I put in ZEX plugs. I do have a walbro intank.


ALright if everybody thinks it is the tune I am showing an 11.8 A/F, but what about the leakdown number?</TD></TR></TABLE>

Don't know if this will help but I heard some really bad things about Zex plugs. Do you have normal NGK plugs?