Little Mouse - The 1994 - 4.3l TBI engine blueprint and tuning
#1
03-05-2016, 04:17 AM
Little Mouse - The 1994 - 4.3l TBI engine blueprint and tuning
Blueprinting that oddball 4.3l V6 TBI with balance shaft.
THE RULES:
1st - I have to stick to this exact engine or my 1994 4x4 S10 Blazer will never get a license plate again! That means NO V8 swaps!
2nd - No way that rule #1 can be achieved by something visual from the outside of the engine - so NO TURBO, NO SUPERCHARGER, NO CARBURETTOR or fancy EFI.
3rd - It has to keep emissions within the OEM limits of the 1994 engine. Keep stock exhaust with catalytic converter, EGR and mufflers. BTW during the research I found out that the primary part of that exhaust for the 1994 blazer (Y-pipe and catalytic converter) is the same as the V8. So anything between the headers and Y-pipe is pretty much useless as it flows the volume of a V8.
GOALS
1st DURABILITY under load (towing). I'm not into repairs every 5'000 miles. Servicing every 5'000 miles is just fine with me.
2nd TORQUE, TORQUE and more TORQUE (hp is related to torque at a given rpm - if you get a high torque output you have high hp at that rpm)
3rd FLAT TORQUE CURVE for towing
4th LOW SERVICING REQUIREMENTS - means realistic valve seat cuttings, not always the lightest in materials (valves and such), quality steel parts for the valvetrain no aluminium rockers. Most probably retain the hydraulic lifters, eventually change to mechanical roller lifters. Valve leash adjustment on a rocker arm engine is easy enough - well once you get by all the stuff and reach your valve covers.
5th HP GOAL is around 200 - 225 shp with modified OEM TBI. For this hp target it will probably require ECU reflash.
================================================== ==============================
THE DISCUSSION POINTS
BLOCK MACHINING
This engine will, at this time not get 4 bolt main caps, simply because of the cast crankshaft. The rpm target will be a redline of 6'000 rpm but with the applied tuning a realistic max hp rpm is between 4'250 - 4'750 rpm. So I have some reserves built in.
OIL PUMP
Still open. The OEM pump will be enough to supply this engine.
DRY SUMP
That's a big temptation as this Blazer comes with the larger radiator with remote oil filter location and heat exchanger to the cooling system. That means plumbing is already half done. Enough room in the engine compartment is there for the tank location (left front). We'll see what happens when it starts coming together.
THE RULES:
1st - I have to stick to this exact engine or my 1994 4x4 S10 Blazer will never get a license plate again! That means NO V8 swaps!
2nd - No way that rule #1 can be achieved by something visual from the outside of the engine - so NO TURBO, NO SUPERCHARGER, NO CARBURETTOR or fancy EFI.
3rd - It has to keep emissions within the OEM limits of the 1994 engine. Keep stock exhaust with catalytic converter, EGR and mufflers. BTW during the research I found out that the primary part of that exhaust for the 1994 blazer (Y-pipe and catalytic converter) is the same as the V8. So anything between the headers and Y-pipe is pretty much useless as it flows the volume of a V8.
GOALS
1st DURABILITY under load (towing). I'm not into repairs every 5'000 miles. Servicing every 5'000 miles is just fine with me.
2nd TORQUE, TORQUE and more TORQUE (hp is related to torque at a given rpm - if you get a high torque output you have high hp at that rpm)
3rd FLAT TORQUE CURVE for towing
4th LOW SERVICING REQUIREMENTS - means realistic valve seat cuttings, not always the lightest in materials (valves and such), quality steel parts for the valvetrain no aluminium rockers. Most probably retain the hydraulic lifters, eventually change to mechanical roller lifters. Valve leash adjustment on a rocker arm engine is easy enough - well once you get by all the stuff and reach your valve covers.
5th HP GOAL is around 200 - 225 shp with modified OEM TBI. For this hp target it will probably require ECU reflash.
================================================== ==============================
THE DISCUSSION POINTS
BLOCK MACHINING
This engine will, at this time not get 4 bolt main caps, simply because of the cast crankshaft. The rpm target will be a redline of 6'000 rpm but with the applied tuning a realistic max hp rpm is between 4'250 - 4'750 rpm. So I have some reserves built in.
OIL PUMP
Still open. The OEM pump will be enough to supply this engine.
DRY SUMP
That's a big temptation as this Blazer comes with the larger radiator with remote oil filter location and heat exchanger to the cooling system. That means plumbing is already half done. Enough room in the engine compartment is there for the tank location (left front). We'll see what happens when it starts coming together.
Last edited by error_401; 06-07-2020 at 04:22 AM. Reason: Update and images added
#2
03-07-2016, 06:33 AM
Without forced induction your only real options would me a lot of machine work, head porting, gasket matching, getting heads milled, thinner head gaskets, etc... The last 2 things may require custom length push rods.
#3
03-07-2016, 03:01 PM
Thanks for the thoughts. That is exactly the plan:
Machine for screw in studs, machine the valve pockets to use beehive springs.
Porting the bowls to the seats, round the sharp edges of the valve guide and port match to gasket and manifold. I can do this work myself so the cost will be reasonable. A little head work in the combustion chambers to equalize the volume, then machine the heads for compression.
At the bottom end I will use new rods and new pistons most probably flat deck and calculate the height to be flush with the block deck. The CR goal is around 10:1, maybe 10.5:1. With the lighter rotating mass (rods and pistons) balancing the crankshaft for internal balance should be possible. To complete I will use a new internal balance damper and remove the weight from the flexplate and balance that with the crank.
At the top end most probably compcams magnum pro steel roller rockers and new custom rods to achieve proper valvetrain geometry.
I have the time and the connections to get it done at a reasonable price. I work with and for a garage and a machine shop. So the machining is covered.
Machine for screw in studs, machine the valve pockets to use beehive springs.
Porting the bowls to the seats, round the sharp edges of the valve guide and port match to gasket and manifold. I can do this work myself so the cost will be reasonable. A little head work in the combustion chambers to equalize the volume, then machine the heads for compression.
At the bottom end I will use new rods and new pistons most probably flat deck and calculate the height to be flush with the block deck. The CR goal is around 10:1, maybe 10.5:1. With the lighter rotating mass (rods and pistons) balancing the crankshaft for internal balance should be possible. To complete I will use a new internal balance damper and remove the weight from the flexplate and balance that with the crank.
At the top end most probably compcams magnum pro steel roller rockers and new custom rods to achieve proper valvetrain geometry.
I have the time and the connections to get it done at a reasonable price. I work with and for a garage and a machine shop. So the machining is covered.
Last edited by error_401; 09-16-2017 at 06:17 AM.
#4
03-18-2016, 11:04 AM
The next step will be re-assembly for measuring. So far I have the data for the material for the build. Now we'll have to determine the deck height to order rods and pistons.
Planning on some SRP 350 flat heads with 2 valve reliefs (adding only 5 cc) - and ended up with a set of custom JE forged pistons at 4.004" to fit an OEM bore which will be honed 0.05 over to fit the pistons. The rods will be either from Carrillo or Eagle. Turned out to be Eagle H-beams. Nice rods. Within 2 grams.
Planning on some SRP 350 flat heads with 2 valve reliefs (adding only 5 cc) - and ended up with a set of custom JE forged pistons at 4.004" to fit an OEM bore which will be honed 0.05 over to fit the pistons. The rods will be either from Carrillo or Eagle. Turned out to be Eagle H-beams. Nice rods. Within 2 grams.
Last edited by error_401; 09-16-2017 at 06:20 AM.
#5
03-18-2016, 01:42 PM
Basically everything that you have mentioned is classified as tampering with the emission control system, which is against US Federal law. The engine will no longer be "emission legal" for 1994 OBD 1. Just so you are aware of that, before starting the project 
#7
03-18-2016, 04:29 PM
Yup, I was on my phone and the mobile app doesn't show where members are. I have a hard enough time remembering what year vehicle everybody has, much less where they live
#8
03-19-2016, 05:13 AM
CaptainHook + Tajohns
you are right.
Usually we have a lot of trouble with modifications you can do easily in the US. But on the emissions side we have an advantage.
We need a dealer inspection every two years with pre OBDII vehicles with a printout of the test to be carried with the vehicle papers. Then during inspection they will measure exhaust gasses again and they have to be within the limits given in the vehicle booklet. We are actually allowed an hp increase as long as exhaust gasses remain within limits of the originally certified engine and it retains all emissions control measures.
The increase in compression, matching components, injection, ignition will most probably lead to lower emissions, not higher. Blueprinting will do it's own keeping emissions within legal limits. As it is not my intention to delete any of the emissions control measures this will pass inspection as long as emissions are within the given percentiles of HC, CO, and CO2.
you are right.
Usually we have a lot of trouble with modifications you can do easily in the US. But on the emissions side we have an advantage.
We need a dealer inspection every two years with pre OBDII vehicles with a printout of the test to be carried with the vehicle papers. Then during inspection they will measure exhaust gasses again and they have to be within the limits given in the vehicle booklet. We are actually allowed an hp increase as long as exhaust gasses remain within limits of the originally certified engine and it retains all emissions control measures.
The increase in compression, matching components, injection, ignition will most probably lead to lower emissions, not higher. Blueprinting will do it's own keeping emissions within legal limits. As it is not my intention to delete any of the emissions control measures this will pass inspection as long as emissions are within the given percentiles of HC, CO, and CO2.
Last edited by error_401; 11-19-2017 at 05:18 AM. Reason: Updating information
#9
03-19-2016, 05:32 AM
What will be done now that I know the block's good:
Get either a new crankshaft or grind the one I have to first undersize.
Check main bore alignment, deck alignment and machine for that.
I will have to test assemble beginning of next week.
New rods 5.700" which makes a little more room for the deck alignment OEM is 5.703".
Best guess at this time is SRP 350 flat deck pistons with dual valve reliefs and 5cc addition to combustion chamber.
A 0.045 gasket (standard) thickness is perfect with a flat top for the squish and will raise CR to 10.2 : 1.
Balance for this rot assembly and as it will be several grams lighter than stock the crank will get completely internally balanced.
Fluidamper in front.
Keep the heads machine combustion chambers for volume adjustment (they range from 64 - 66 cc) then grind the bowls lightly just to match and get rid of ridges. Put a radius similar to the valve stem's on the valve guide. Then recut the valve seats for a 3 angle valve job and fit Milodon stainless steel valves. (nothing too fancy).
On top machine the guide boss to accomodate the new spring and shorten it a bit to get the required clearance for the new valve lift.
Machine the spring cups for the larger springs and the stud bosses for same height (depending on valvetrain geometry) and 3/8" screw in studs.
Beehive springs will get steel retainers and paired with CompCams Magnum Pro steel roller rockers at 1.6:1 ratio should be good for a 6'000 rpm redline with reserve to 6'500 rpm.
And of course new lifters and pushrods will be fitted, the latter custom lenght, again for proper geometry.
At this point I think that next weeks test assembly will have me ready to start ordering parts. Once I know if the block is square or how much to grind down I can derive compression height and order stuff.
I think I got my stuff together...
Get either a new crankshaft or grind the one I have to first undersize.
Check main bore alignment, deck alignment and machine for that.
I will have to test assemble beginning of next week.
New rods 5.700" which makes a little more room for the deck alignment OEM is 5.703".
Best guess at this time is SRP 350 flat deck pistons with dual valve reliefs and 5cc addition to combustion chamber.
A 0.045 gasket (standard) thickness is perfect with a flat top for the squish and will raise CR to 10.2 : 1.
Balance for this rot assembly and as it will be several grams lighter than stock the crank will get completely internally balanced.
Fluidamper in front.
Keep the heads machine combustion chambers for volume adjustment (they range from 64 - 66 cc) then grind the bowls lightly just to match and get rid of ridges. Put a radius similar to the valve stem's on the valve guide. Then recut the valve seats for a 3 angle valve job and fit Milodon stainless steel valves. (nothing too fancy).
On top machine the guide boss to accomodate the new spring and shorten it a bit to get the required clearance for the new valve lift.
Machine the spring cups for the larger springs and the stud bosses for same height (depending on valvetrain geometry) and 3/8" screw in studs.
Beehive springs will get steel retainers and paired with CompCams Magnum Pro steel roller rockers at 1.6:1 ratio should be good for a 6'000 rpm redline with reserve to 6'500 rpm.
And of course new lifters and pushrods will be fitted, the latter custom lenght, again for proper geometry.
At this point I think that next weeks test assembly will have me ready to start ordering parts. Once I know if the block is square or how much to grind down I can derive compression height and order stuff.
I think I got my stuff together...
Last edited by error_401; 10-16-2017 at 08:11 AM. Reason: Image added
#10
04-18-2016, 02:33 AM
Major order at SUMMIT done yesterday night.
- Some gaskets
- ARP screw in 3/8" rocker arm studs
- 1 (one) COMP magnum pro rocker roller at 1.6:1 (for geometry checking)
- camshaft
- timing gear
- EAGLE rods H-Beam rods at 5.7" length
and last week finally got my test assembly and got deck heights and stuff. The block is nice and straight may need some 1/1000 angle decking to get it straight to the main bore. The cylinders are round and just need a couple 1/1000 of honing.
Pistons orderd
- Custom forged JE pistons with flat top and two reliefs to get a target 10:1 compression
- Ring set in file fit. All at 4.004" exactly. The hone will provide the necessary clearance for the forged pistons without the need to overbore.
We pay a lot for machine and labor hours here in Europe therefore replacing pistons with forged ones is actually a saver. I have access to a machine shop and can do a lot of work myself. This helps in expanding what can be done to the engine.
Instead of cutting the decks by nearly .025 inches to achieve a zero deck with shelf stuff we'll order custom pistons. Less hassle, less valve pockets.
Had to get them at 1.600" CD therefore the custom order. Hopefully not too much higher in price than the shelf stuff.
The compression of the stock engine is between 8.8:1 and 9.0:1 (sucks).
Gee this engine has no squish on the heads at all! The distance to the bottom of the piston dish including how much below deck it is and the gasket is nearly a 1/4" (5 mm).
Will be interesting to see the improvement once this engine runs.
- Some gaskets
- ARP screw in 3/8" rocker arm studs
- 1 (one) COMP magnum pro rocker roller at 1.6:1 (for geometry checking)
- camshaft
- timing gear
- EAGLE rods H-Beam rods at 5.7" length
and last week finally got my test assembly and got deck heights and stuff. The block is nice and straight may need some 1/1000 angle decking to get it straight to the main bore. The cylinders are round and just need a couple 1/1000 of honing.
Pistons orderd
- Custom forged JE pistons with flat top and two reliefs to get a target 10:1 compression
- Ring set in file fit. All at 4.004" exactly. The hone will provide the necessary clearance for the forged pistons without the need to overbore.
We pay a lot for machine and labor hours here in Europe therefore replacing pistons with forged ones is actually a saver. I have access to a machine shop and can do a lot of work myself. This helps in expanding what can be done to the engine.
Instead of cutting the decks by nearly .025 inches to achieve a zero deck with shelf stuff we'll order custom pistons. Less hassle, less valve pockets.
Had to get them at 1.600" CD therefore the custom order. Hopefully not too much higher in price than the shelf stuff.
The compression of the stock engine is between 8.8:1 and 9.0:1 (sucks).
Gee this engine has no squish on the heads at all! The distance to the bottom of the piston dish including how much below deck it is and the gasket is nearly a 1/4" (5 mm).
Will be interesting to see the improvement once this engine runs.
Last edited by error_401; 07-20-2018 at 11:18 AM.