Bill Ball

One one GTS here at least, severe coking of the combustion chambers, raising the compression to 210, lead to severe pinging. We had the intake system cleaned with a BG Products treatment, compression came down to 200-205 max, and the pings disappeared.

PorKen

Stock 32Vs have WR7DC. You want WR5DC, the coldest extended plug for Bosch. (Fouling is a myth.)

Bosch numbers are lower numerically for colder (for NGK, colder is higher #s).


You should start by disconnecting the WOT input to the EZ-K at the ECU connector (or cut the wire). Then ST the cruise map. The EZ WOT map is flat, ie rpm based only, with no compensation for air density.

Louie does this, as well as zeroing out the LH WOT map (which adds to the base map, unlike the EZ map), and tuning just the base fuel map.

AO

Maybe this was alread covered, but what size injectors will be installed? If you're going to run anything less than 30lb, I think you may have issues using those chips.

Also, using a boosted chipset as a surrogate, will probably introduce some rather interesting fueling characteristics - some fat, some lean... just be careful.

AO

Whoa! That's a littel over simlified (BTW, I like the idea of disconnecting the WOT switch). They first have to get teh fueling (LH) about right. Then move to Ignition timing, then go back and fine tune fueling if needed.

Bill Ball

Mark has 30 lb injectors. We'll install the LC-1 wideband and see where we are. With this motor, even if by some magic the fueling and timing is OK, Mark needs to be a bit gentle for the first 500 miles, doesn't he?

hacker-pschorr

This is the first time I noticed you were using the extended plug. I thought they had an extra character in the model number.

It might not be a bad idea to try the plugs Todd uses in his car. They are a non-projected racing plug (about $1.50 at our local Farm Supply store, not kidding) by NGK. He saw some fouling during the cold months during stop / go driving, should not be an issue at all in your car in NorCal. These are the plugs of choice with the import tuner crowd, designed for constant high rpm's where you are trying to avoid the spark plug turning into a glow plug.

I'll try to find the number, if you cannot find them locally I can send some out there ASAP if you are interested.

Is high load / low rpm still the rule of thumb for a new motor?

dprantl

My boosted 928 likes the NGK BCPR7ES plugs. They are very cold but have a wider range than the equivalent Bosch plugs.

Dan
'91 928GT S/C

AO

Just let it idle in the driveway overnight. Good to go!

































j/k

PorKen

The coldest 928 threaded Bosch projected tip is the 5, WR5DC. But the regular, non-projected tip goes at least to 2, WR2CC. (D = projected, C = regular)

A non-projected tip with the same heat range is cooler than a projected.

marlinspike

But you want a projected tip if you can.

hacker-pschorr

Duh, brain fart....

The boosted crowd goes the opposite way, so I've been wondering if a high compression race motor would fall under the same theory.

AO

I wouldn't think so. 30psi vs NA... Hmmmm....

mark kibort

Good info Guys!

Ill see if i can get the WR5 or 6DC and give them a shot.

as was mentioned, i have very low mileage 30lb injectors that are going in courtesy of George (great deal!)
Ill back the fuel pressure off from the 72psi i ran on the holbert engine, down to about stock 52ish.

by the way, all this talk about sacrafices with the cam timing. the 85 cams are a natural for this. they are a full 8 degrees retarded , over the entire duration vs the GT cams. in otherwords, i dont even know if the porken tool could retard the GT cams this much! however, the exhaust cams are the same effective timing and duration. what would the retard of the exhaust cam create? anyway, with an already head start on reduced cam timing, and the ability to reduce torque and power in the mid range Rpm by flappy disconnect, i think we are in good shape.

mk

hacker-pschorr

I said high compression, like a small block N/A making over 900hp with pushrods and mechanical fuel injection

PorKen

Correctly stated, GT intake cams are 8° (crank) advanced. S³ intake valves open at the same point as S4 cams, 11° ATDC, but close later.

I made >15 rwhp more by going from +3° advance to -1° retard with my S³ cams, same dyno session. The tq/hp peaks move about 100 rpm with each crank° ±.

Going to -4° raised the peaks even higher, didn't lose hp, but didn't gain, I'm fairly certain because the exhaust was restricting it. With a revised exhaust, it feels much more powerful - dyno soon.

The 32V gears have a ±7.5° range in the slots, so with the 32V'r (aka PorKen tool) you have a 15° range, no matter which cams you have, S³, GT, S4, or GTS.