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4.3 performance upgrade

  #1  
Old 12-24-2018, 09:49 AM
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Default 4.3 performance upgrade

Forgive me if this is in the wrong place. I am going to replace the engine in my 02 Zr2 and want to get more ponies (50) out of it. I have looked in the performance and internals section and didn't find what I was looking for. I need direction as to a good thread or article that will help me with things like cam, intake and injectors. I have a local guy that can tune it for me once I have the specs for what I am doing. Using google I find a bunch of crate motors but non over 200HP. During this search I did find a couple of articles that said I didn't need to use headers, that stock manifold would work just fine if I delete the cats and put on performance exhaust. This will be a spring season job so I have time to research and gather parts before I begin. I first considered swapping to a V-8, have done hundreds of them back in the 80's & 90's but all were carb vehicles that didn't require swapping ECM and electronics and don't really want to get in to any of that. Any help would be greatly appreciated.
 
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Old 12-24-2018, 02:11 PM
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I am exactly in the same place as you. Although would love a V8 swap, it just doesn't fit the budget at this time. I did a V8 swap into a volvo 15 years ago, and the price to do it right was crazy.

i would like to keep my 4.3L build around the $3000 range.

Biggest problem I see is that our current fuel injection system really cant produce much more air/fuel volume being pushed through the engine. Keeping in mind an engine is nothing but a giant air pump.

I have gone over multiple scenarios that include a bigger cam kit with springs. Bore the Block .030 over with new pistons. Shave the deck and heads to produce a little higher compression. Perhaps find a marine intake with the fuel rails so I can increase injector size. Our ECU from what I read, will still be the limiting factor. Our stock exhaust system seems to be a great flowing system. Maybe some head porting, although I can't find any solid facts that it is worth it on these particular heads, I need to research that more.

The only other alternative for me is to put a Jasper or ATK crate motor in and find a used supercharger system on it with a dialed down PSI.

Thoughts?
 
  #3  
Old 12-24-2018, 06:59 PM
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I went the super charger route on my 99 and wasn't impressed.
 
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Old 12-25-2018, 05:48 AM
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IMHO the V6 has the potential to do 200 HP easily. There are just not that many bolt on solutions that work out of the box.
The V6 has seen such a broad use in vehicles over the years but has always been considered a "normal" engine. All tuning efforts have always been into the 350 V8 from which the V6 has been derived. Unfortunately for us there are no such solutions for the V6 because it has seen very little tuning being considered "pathetic" by most.

I'm on the way to that 200 - 250 HP 4.3 V6 but it is still in the build as I'm not in a hurry.

This is my build diary:
https://blazerforum.com/forum/builds...ueprint-92047/

Been discussing it with a guy from the ECU tuning. They do all sorts of sportscars and race-cars up to the Lamborghini Huracan. He suggested to try with the OEM fuel injection by modifying the mapping in order not to mess up all the other things the OEM ECU does. Adapting a new fuel injection is in his opinion a 6 months job, because we would have to reproduce all the things the OEM ECU already does such as:
- cold start
- inputs and outputs to the gearbox TCCM
- knock control
- ignition control
- and many many more.

At this time for a 1st gen I don't see the advantage of removing the catalytic converter. According to my calculations on the V6 this will be limiting only on rpm ranges above 4'500 rpm which is hardly any range the truck will ever see. All behind the cat may help a little (in the order of 1 - 3 hp).
This is the difficulty with tuning this engine. There is no information about what has been done to it and the real changes that it yielded. Nobody ever bothers to supply hard data after swapping out their catalytic converters and replacing the exhaust with a high-flow high diameter piping.
And - IMHO many of these are just for looks and sound and will mess up your fuel economy and probably reliability.

While my 1st gen build based on OEM pre kidney shaped combustion chambers may be even more trouble than a more modern 2002 ZR2 I should still be able to see 200 hp at the engine vs. the 165 hp advertised. Once the engine is complete, I guess end of 2019 I'll put it to the test by doing a comparison run with the OEM vs. built engine.

But for us venturing into tuning it's still just fun to tinker with engines.

Merry Christmas
 

Last edited by error_401; 12-25-2018 at 06:14 AM.
  #5  
Old 12-25-2018, 08:31 AM
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error_401

Would be nice one day to just put a set of zero deck flat top pistons into an OEM engine without any other changes and see what the outcome is. (3 - 5 % more hp/torque?).
I really like that idea.

Great thread/build you have, what a perfectionist you are, and you're passion for your build is amazing. Fantastic thread!

Nitriding...learn something new every day.

Good luck in getting her done.
 
  #6  
Old 12-25-2018, 12:12 PM
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these trucks are 195 hp stock. Anyway I installed a cam, headers, high flow exhaust and cat. High output ignition and had a tune after all of that. Definite increase in power and put you in the seat acceleration. I`m betting is was in the 220 hp range
 
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Old 12-26-2018, 04:41 AM
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Yeah, true. the 1994 is rated 165 hp the later models saw a steady increase in hp over the years.

I'm looking forward to see the output on my pathetic 1994 TBI once it's finished, hoping to see it in the 200 + hp range.
 
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Old 12-27-2018, 08:12 AM
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I am becoming more and more intrigued with the marine intake idea. Anyone have any experience with this type of mod? Seems the marine intake gives the advantage of different size injectors and being able to port match to the heads. What I haven't seen yet or just don't understand is how the marine injector gets the fuel into the combustion chamber and do you use the TB off the OE manifold.
 
  #9  
Old 12-27-2018, 09:00 AM
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I'm in the process of the marine intake swap. I gasket matched the ports(I previously did my heads as well) there is a significant difference between the gasket and the factory ports...1/4 of an inch in some spots so I feel it is a good thing to do.

You do use the factory throttle body housing. There is a 25 dollar adapter to make the 3 bolt throttle body on our trucks bolt right up to the 4 bolt marine intake.

the injectors are on a fuel rail and plug right into the lower intake, it injects the fuel directly into the intake runner ports of the lower intake, just as the factory one does- it just uses the external injectors with a fuel rail as opposed to the internal spider style the factory did.

Throttle body adapter
 

Last edited by chevyriders; 12-27-2018 at 09:13 AM.
  #10  
Old 12-27-2018, 12:54 PM
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Chevyriders.....Pics and a wright up would be great if you are up to it. The adapter solves one of the problems I have read about, the other issue was wiring in the new injectors. I will be following this closely.
 

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