So I've installed my EGR delete kit from BC (thank you sir). And I've noticed something on the intake manifold.

There seems to be a soot stain on the top from the back of the EGR valve. The gasket that was on it appeared original, not like the newer stamped metal gasket that BC sends with the kit.

Anyhow. My RPMs have lowered and the turbo seems to kick in a hair faster. I also seem to be getting more miles on this current tank. I'll need more than one tank to say I'm getting better mileage, I know. Granted this is all butt dyno and I don't have a boost gauge installed. Would loosing a small amount of exhaust pressure (pre-turbo) really have this effect?

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'85 300TD "Puff The Magic Wagon" - Rolling Resto
'19 Mazda CX-9 Signature - Wife's sled
'21 Morgan 3-Wheeler P101 Edition
'95 E300d - SOLD
'84 300TD "Brown Betty" - Miss this one
'81 240D "China Baby" - Farm grocery getter

it all depends on how much it was leaking. but yes. turbo requires pressure to function, a leak depletes that pressure.
the pic is not great, but that could simply be grease that cooked near the heat of the EGR too. is it powdery soot, or black stain?

I know the turbo relies on pressure to spool up, but I'm more interested in the RPM drop. Didn't make that very clear in original post. I'm assuming that the leak at highway speeds would cause the turbo to not reach full boost, therefore requiring more throttle and RPMs to maintain highway speed?

Pic is from my phone, I'll take better pics of the manifold and EGR valve tonight.

The stain is not very sooty and doesn't rub off much. It comes straight from the flange down onto the top of the manifold.

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'85 300TD "Puff The Magic Wagon" - Rolling Resto
'19 Mazda CX-9 Signature - Wife's sled
'21 Morgan 3-Wheeler P101 Edition
'95 E300d - SOLD
'84 300TD "Brown Betty" - Miss this one
'81 240D "China Baby" - Farm grocery getter

More throttle possibly, but the same RPM.

Also, the leak would have to be pretty large to be significant at highway speeds.

__________________

Gone to the dark side

- Jeff

RPM could drop. (the speed you feel the turbo response) in otherwords, the PULL from the turbo/fuel ingestion could occur sooner, and you would be at a lower RPM when this occurred. because of the mildly improved exhaust pressure.

No change in RPM.

__________________

Gone to the dark side

- Jeff

yup. the ONLY thing that will change RPM's at a certain speed is gear ratio changes. (assuming the torque converter slippage has not changed) so, if it's the same trans, same TC, same tires, and same Differential then the RPM's at a given vehicle speed will be the same.
it's POSSIBLE that vehicle RPM's would go up actually with a stronger functioning turbo due to the additional HP the motor is putting out causing the TC to slip slightly more... but it's almost impossible for this to occur and the slippage would be minute.
the only thing a better turbo seal will show in RPM's is the point in the drive where boost builds.

Problem with that is that if the engine is putting out additional HP, the car will go faster, the speed/rpm ratio will be the same on level ground unless you've grown a trailer.

__________________

Gone to the dark side

- Jeff