i was wondering how much boost could a stock 4.3 handle
with completly stock internals and fule delivery systems?
would you have to use a differnt computer/ computer programer for any boost? are there different sensors for boost like a different map sensor?
just courious thanks

 

A stock internal and FI system can handle about 8-10psi with proper fuel and ignition map.
Depending on year... You'll need to use HPTuners to edit the ecm in several perameters (Power enrichment) Ignition timing (less in higher MAP levels)where boost will be present.
Your stock Injectors are 23.1lb/hr They will only flow so much fuel. So when you get to the point where your AFR's are dropping off. It's time to upgrade to the Marine style intake for the ability to run larger injectors and a better overall internal air flow.
You can use stock Syclone/Typhoon exhaustmaifolds and turbo/downpipe for a simple swap or guys have made a rear mount setup as well. Just depends on budjet and abilitys to fabricate.
Hope that helps answer some basic questions.
If you've got more feel free to e-mail me anytime.
UR50SLO@aol.com
~Scott

 

Scott, not sure what implications are present when you are talking about a '94 (CPI motor... Only 1 injector). And I'm not sure what the flow rating of that injector is... The induction system and internals should be able to handle the pressure, but I'm not sure that the fuel system would be.

Also, being an OBD1 vehicle, HPTuners won't work.

To make this work, I think the best way to go about it would be a Syclone/Typhoon intake/fuel system and the rest of the components (exhaust/turbo/downpipe) that Scott mentioned.

 

Tuner Cat might have somthing for that weird in-between year. I've not worked with that allum. style plenum before or injector. I'm sure the size is similar to the 98. in the low 20lb/hr.
It'd take some investigation and experimenting to see what would work but it's do-able.. bottom end would work fine.
Playing around gettting it to work is half the fun!!!!
~Scott

 

im sorry but i am going to have to say that 8-10 psi with stock everything, there is no way. like swartlkk said the fuel system would not be able to keep up. when i calculated it for my motor a 97 4.3l at 10 psi, with the stock injectors the fuel pressure would have to have been raised to 94 psi to meet the fueling needs. this of course implies the use of a fuel pressure regulator with rising rate for boost.


in my opinion you can safely run up to around 5 psi (MAX.) with stock everything.

at that level you would not need new sensors givin that the maf is able to handel the flow (which it probably could) the map would be out of its range, and in order to make it read properly you would have to convert to a 2 bar map. which requries alot of custom tuning. in eaither case tuning would be advisable.


if you are going to go to the truble to turbo it would be worth it to invest a little more and upgrade the fuel system. for safety and power.

 

Right... need a Warbro 255lr/hr pump installed in stock location.

I went with the Marine intake so I can run larger injectors. (33lb/hr) Stock Typhoon injectors to be specific.

The OBD2 ecm does not support a 2or3 bar MAP at this time (with HPTuners anyway)
There is several perameters that need to change for boosted engines.
Power enrichment multiplyer and spark timing to begin with.
We are running 10-13lbs of boost right now daily with no problems.
There is Nothing else avalible for the spider style injector/poppets to upgrade.
That's why I went to the Marine intake. It uses standard style injectors and fuel rail. I've converted 2 so far to the Marine intake. The 99 Blazer I just put it on is still N/A right now. We have a Typhoon turbo setup ready to go on it just waiting for a free weekend to finish it up. He's been driving it with the Intake for several weeks... For about 500.00 for intake and fuel pump your ready for boost.

 

another route for additional fueling is adding one more cold start injectors into the charge pipe for more fuel.its not too hard to fab up.

 

Hi all, Took my car to Well Lane Turbos yesterday to get it set up properly with the chipped ECU. Found out that the Map Sensor on the ECU is faulty. I have a Series 1 ECU that has a working Map Sensor in it. Can i swap the sensors over by soldering it on? Hope someone can help. Cheers Dave