New to wastegated turbo

[pelky350]

I drove a bone stock pretty much all original factory turbo 94 idi 5speed today and it was so weird ! It had some issues that I'm gonna help the owner with but now I can feel how far I've come from stock! I'll have to make a thread on the work being done to this other truck and pictures of the strange random things I've found just in a quick look around on it! First thing to go will be the tiny tailpipe section and huge gas muffler! Barley can feel air out of the exhaust pipe poor engine is sufficating!

 

[IDIBRONCO]

That and get rid of the factory downpipe will help the other truck out a lot.

 

[pelky350]

Im not sure they want that far into it it's just a camping home working rig i think they just want me to fix it back to like normal running condition, like filters belts fix random broken things and stuff, maybe I'll talk them into making some minor mods to it!

 

[IDIBRONCO]

Their loss I guess.

 

[typ4]

So , making 10 lbs before 2k is awesome, thats pretty good fueling . With ic you may loose a little boost but gain power and reduce smoke.
I know many have done it but dont go over 15 with stock bolts.

 

[pelky350]

I keep it below 15psi so not too much wot time, my pump tested at 108cc at 1000rpms and slowly drops to 95cc at 2800 or 3000 I can't remember and defuel is at 3800 rpm said my pump sheet. Labeled as a 90cc pump but that just means it's minimum fueling is 90cc at 28 or 3000 rpms

 

[shawn deere]

I keep it below 15psi so not too much wot time, my pump tested at 108cc at 1000rpms and slowly drops to 95cc at 2800 or 3000 I can't remember and defuel is at 3800 rpm said my pump sheet. Labeled as a 90cc pump but that just means it's minimum fueling is 90cc at 28 or 3000 rpms

108cc at 1,000 sounds like a f load! Lol. Dont know much about fueling rates vs rpm. But holy smokies

 

[no mufflers]

Why would there be more fuel at lower RPM? can someone explain.

 

[shawn deere]

Mosquito control? Lol

 

[snicklas]

Why would there be more fuel at lower RPM? can someone explain.

I am not a pump builder, an engineer or a physicist...... but I believe it all has to do with available elapsed time.......

The DB2 pump has 2 plungers/pistons (the 2 in the DB2, a DB4 that GM used has 4 plungers) that pressurizes the fuel being sent out each injector hard line. There is a port this fuel is being send out in the rotor of the pump. At a lower RPM, this port is "exposed" to the plunger for a longer period of time (remember all of this is happening in the milliseconds time frame, so everything is happening fast, it's just slight variations in fast), so plunger has longer to push fuel through the port. As RPM increases, the port has less time with the plunger. Also there is other factors at play, there is the timing advance the the fuel governor involved also. I may be totally off base.... if so maybe someone that knows more about this will chime in.

 

[pelky350]

It is a lot of fuel till the turbo catches up lol

 

[Macrobb]

It is a lot of fuel till the turbo catches up lol

This is why you need a Hypermax "Smoke Puff Limiter" - it's effectively a boost-referenced-fueling-regulator for your DB2 pump.

It works amazingly well, and gives you more usable power down low, as you aren't over-fueling it.


As far as turbo overspeed, well, I've run my Banks TE06H on my 88 for a couple of years pushing well over 15 PSI - I hit 22 more than a few times on hard acceleration(wastegate unplugged as usual).
The engine had more trouble with it than the turbo did - the turbo's still just fine, no looser than it ever was.
The engine bent a couple exhaust pushrods at that pressure, and didn't make any more HP than when I had less fueling and maxed it out at 15 PSI.