pcmhacking.net

i can supply exhaust stuff cheap for members here as that is what morex stands for! good to here might get that on the go. Just got home from summernats not sure on the outcome of the event!

Ran it a week or so ago with the new engine which is still a work in progress in terms of the tune. Engine specs are 410cube stroker, solid roller, brodix alloy heads, 12:1 comp and on ultimate98. Made 410RWHP at just under 5k RPM before the camira ignition module could not provide enough spark and started missing - now the camira module is feeding an MSD CDI setup. Peak VE is 6200-6500RPM so should make a fair bit more HP now it spins to 7500RPM.

Best run of the night was a 10.49 on the brakes (only ran 100MPH trying not to break out). The first three qual runs had some issues with the trans brake so were around the mid 10.5 but 128MPH.

After the 10.49 it appears to have a bearing issue so didnt run it again, plus the convertor is slipping pretty bad - nearly 7k RPM @ 128MPH, should be doing nearly 140MPH at those revs - so thats getting a tickle too.

New headers are being made (using 1" 7/8 piping and slip on merge collectors). It pulls some vacuum (94kPa down from baro of 100.8kPa) on the 1-2shift and slightly through the finish so might look at the intake too.

Hopefully the bottom ends allright. Sounds like its going to be dipping into the nines by the time you sort the exhaust, converter and intake. Did the change to ally heads require a different intake and whats the transition from manifold to head port like? - could be your pulling vacuum issue

We are hoping to see a low 10, a 9 would be a huge bonus but not sure there is that much left in it.

Intake is the same as the old motor, its a mopar single plane thats been port matched to the alloy heads. While its apart will have a look at the transition again though. Would be far easier than a new intake setup!

VL400 wrote:Would be far easier than a new intake setup!

and a damned sight cheaper too has any plenum work been done to the intake?

how about a few shots of the intake and a sticky up your throttle body adaptor while its off would be cool

Will get some and post them up soon Intake has only been port matched otherwise un-touched.

Engine back together, the issue was top ring clearance and a grout filled block. When it gets hot it gets a tad tight, bore looks fine so no damage but will need to be careful with hot restarts until pulling it right down at the end of the season. The issue was enough to also point out some short-commings in the starter motor wiring so have fixed that and it cranks better now too - 10v at battery and 9.3v at starter compared to 7.8v when we started investigating. Battery may be a little undersized but so long as its kept charged seems to be ok.

The convertor also had a tickle up and is heaps better now, no more top end slip and nice and loose down low.

So... first qual was looking good until the throttle cable screwed up - nice launch and then throttle snapped shut just before the 60' mark. Second qual fri night with 280 meter air qual saw an 10.30 so pretty happy, thrird was sat morning in 600 m air and got a 10.40. First round of racing saw a nice cherry on the tree so game over

New pipes will hopefully be getting made soon and we need to investigate a random misfire.

Basic setup is a chrysler reluctor dizzy. Delco ECU feeds a camira ign module which passes the output to a MSD 6AL-2 and MSD HVC-2 coil. Spark output should be more than ample for this motor. It is not always as bad as this log either, the 10.30 run was cleaner. The LM2 RPM input is taken from the distributor ref signal - camira module feeding the delco - and looks pretty clean. And as can be seen, in 1st gear it misses at a bit before 6500RPM but crosses the line in top at 6500RPM with no misfire.

Anyone got some ideas??

almost looks like a fuel surge issue is that possible with the setup thats on it

looks like its leaning out before the acceleration falls off

if the leads are still paired id seperate them as if had induction issues with leads before and can be hard to pinpoint

also maybe close plug gaps to 30 thou

looks like the afr graph is wavy due to map pressure fluctuation id look at modifying trumpets for better flow and changing the air scoop on the bonnet as this could cause the pressure beffeting seen on the map log

just looking at the graph again every time it goes over 105kpa on the graph just after that you get the "misfire" leanness as shown in the afr log

id say its spark by the look of it or you need to fatten up the fuel table to make the mix burn with the higher map pressure

might be a glitch making it lean out over 105kpa with the 1 bar setup?????? nfi lol

could be a spark problem with a lead or as said seperate leads from their pairs or maybe coil or the firewall plug could be leaking current

Fuel surge could be an issue, although tank was nearly full (20L with some internal baffeling and lowered pickup. Fuel pump is a bosch 044 and lower than the pickup point). We dont run a surge tank, has been like this for a number of seasons and never had an issue although its now a fair bit quicker. I do have a surge tank and we have the old BG 400 pump from the carb days so could try that fairly easily. Might actually add a fuel pressure monitor for the next meet, have been meaning to so prob a good time

The unfiltered MAP signal ranges from 93-103kPa which is not real good - it used to be really stable but lots has changed since then. Although the LM2 is crap when it comes to getting reliable signal levels so will get a TP5 log and compare. The intake is not sealed against the bonnet scoop so the airflow is all over the place!! This log was before the latest firmware update, nothing has changed with our setup and check out the totally unusable RPM signal (black trace) and noisy other channels but no misfire ... The leads are paired up and was one thing we thought of changing but didnt get another run The other thing we will check more carefully is the dizzy rotor lining up with the post at 34deg advance, never checked that since converting it to EFI. Not sure what plug gap is either, will check that one.