3.8 FWD into our cars, can it be done, pros, cons
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Red Regal T
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It's been discussed before..........not feasible. Totally different motor. Different transmission bolt pattern, different crank etc. More GM help. 
We'll sell ya a brand new chevy motor, though.
We'll sell ya a brand new chevy motor, though.turbojustin
Ninja
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Before I begin...I am NOT an expert on this, so please be nice. I have not tried what is described below. I am only basing my reasoning on internet research, not hands on experience. With that said, let the flaming begin.
I think when people say the FWD 3.8 is a completely different engine they are usually referring to the 3800 series which began in 1988. Take a look at the link below. Most people forget about the 85-87 FWD 3.8. Those engines have atleast partially interchangeable parts (Not exact part #s, but possible swaps).
I have been considering the same idea, atleast in part. Rather than swapping out the whole motor, I plan to use just bolt on parts for my application. I already have a turbo longblock. What I don't have are the accessories(a/c compressor, alternator, brackets, intake, etc). I like the idea of the FWD application because of the $$ factor and the serpentine belt. I know it won't necessarily be turbo correct, so to speak. But it will function well. My project car is an NA regal so it doesn't need to look like an OE turbo car. I know certain things may have to be customized (wiring harness, ac lines, etc). Right now I'm still in the planning stages because I'm broke from my TR resto and soon I'll be married, so the money isn't exactly flowing. But, seeing how I can get a complete 3.8 FWD engine for under $200 it is worth a try. Is there any reason this won't work? One thing I've heard is that the FWD intake will have cooling problems if I flip the intake 180 degrees to put the tb in the front. If the heads can go on either side of the engine then why would there be a problem with coolant flow? Could someone please explain this.
I'll keep you posted when I get things going.
Here is a helpful link.
http://members2.easyspace.com/hotholdens/tech/v6hist.html
I think when people say the FWD 3.8 is a completely different engine they are usually referring to the 3800 series which began in 1988. Take a look at the link below. Most people forget about the 85-87 FWD 3.8. Those engines have atleast partially interchangeable parts (Not exact part #s, but possible swaps).
I have been considering the same idea, atleast in part. Rather than swapping out the whole motor, I plan to use just bolt on parts for my application. I already have a turbo longblock. What I don't have are the accessories(a/c compressor, alternator, brackets, intake, etc). I like the idea of the FWD application because of the $$ factor and the serpentine belt. I know it won't necessarily be turbo correct, so to speak. But it will function well. My project car is an NA regal so it doesn't need to look like an OE turbo car. I know certain things may have to be customized (wiring harness, ac lines, etc). Right now I'm still in the planning stages because I'm broke from my TR resto and soon I'll be married, so the money isn't exactly flowing. But, seeing how I can get a complete 3.8 FWD engine for under $200 it is worth a try. Is there any reason this won't work? One thing I've heard is that the FWD intake will have cooling problems if I flip the intake 180 degrees to put the tb in the front. If the heads can go on either side of the engine then why would there be a problem with coolant flow? Could someone please explain this.
I'll keep you posted when I get things going.
Here is a helpful link.
http://members2.easyspace.com/hotholdens/tech/v6hist.html
The only thing I know of that may help you guys is that you "should" be able to use the tranny from a 2.8 liter s10/blazer whether it be a 700R4 or a little 200C and I'm almost sure the bellhousing will line up right with the FWD motor. Torque converter bolts may not line up with flywheel holes so you may have to drill the flywheel to match but you may not have to also. Good luck getting the tranny to hold any amount of torque or abuse.......
bob
bob
MeanBuicks
Scaring the neighbors!
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Late model F-bodies had the Series II 3800 as the base engine and they're RWD. I always thought swapping a supercharged version into one of those would be a hoot. 
turbojustin,
I agree, the 86-87 fwd gets you the better gerotor oil pump, roller cam (VIN "3"), serpentine setup, etc. I wish that I had looked into this a little closer before committing to rebuilding my NA rwd 3.8. I should have picked up one and stripped it down and compared all the pieces side to side with my rwd 3.8. Might be some mix and match possible. Here are some of the things I figured out before bailing.
1.) The tranny pattern is 60 Chev V6, so you can use the S10 700R4. It bolts up, the flexplate and starter also work. Same for 3800. May need spacers between flexplate and torque converter. My tranny guy can build me a 700r4 dirt cheap.
2.) Motor mount pads are machined. Front bolts are drilled. Some of the blocks I looked at don't have the rear bolt holes drilled/tapped. I don't see why you couldn't drill/tap the rear holes. Same for 3800 series I I looked at.
3.) Pan has wrong sump. I don't remember if the 86-87 fwd has same pan rails as rwd. Might get lucky and just use rwd pan. The 3800 definitely has different pan rails. Whack pan. I also don't remember if the pickup tube bolts at the same angle. Whack pickup.
4.) Timing cover has lower radiator hose outlet on opposite side. This would require some creative plumbing to route the hose down, forward and then across. Not hard. Also has oil filter adapter sticking straight out to side. ?
5.) Accessory brackets place accessories low on the sides, may not clear. ? Modify brackets.
6.) Do not know why flipping intake would cause overheating. As installed the crossover passage and thermostat is on the 'back' of the engine. Flipping it would put it back up 'front' like the rwd. Does this have to do with heat crossover passages or EGR or something else I haven't thought of? If this is a problem, then install like fwd, with air intake from the back. There may not be enough room at the firewall for an elbow without modifying the intake. But that's doable. Could also use modified 84-85 hot air intake or 86-87 turbo intake.
7). I don't remember if the 86-87 heads have the same exhaust ports and could use the rwd exhaust or not. May have to mod rwd or fwd setup to get something to work.
With all this said, I don't think it would be much harder than this to make a 3800 series 1 work, either. Any other show stoppers you aware of?
Adios,
Brett
I agree, the 86-87 fwd gets you the better gerotor oil pump, roller cam (VIN "3"), serpentine setup, etc. I wish that I had looked into this a little closer before committing to rebuilding my NA rwd 3.8. I should have picked up one and stripped it down and compared all the pieces side to side with my rwd 3.8. Might be some mix and match possible. Here are some of the things I figured out before bailing.
1.) The tranny pattern is 60 Chev V6, so you can use the S10 700R4. It bolts up, the flexplate and starter also work. Same for 3800. May need spacers between flexplate and torque converter. My tranny guy can build me a 700r4 dirt cheap.
2.) Motor mount pads are machined. Front bolts are drilled. Some of the blocks I looked at don't have the rear bolt holes drilled/tapped. I don't see why you couldn't drill/tap the rear holes. Same for 3800 series I I looked at.
3.) Pan has wrong sump. I don't remember if the 86-87 fwd has same pan rails as rwd. Might get lucky and just use rwd pan. The 3800 definitely has different pan rails. Whack pan. I also don't remember if the pickup tube bolts at the same angle. Whack pickup.
4.) Timing cover has lower radiator hose outlet on opposite side. This would require some creative plumbing to route the hose down, forward and then across. Not hard. Also has oil filter adapter sticking straight out to side. ?
5.) Accessory brackets place accessories low on the sides, may not clear. ? Modify brackets.
6.) Do not know why flipping intake would cause overheating. As installed the crossover passage and thermostat is on the 'back' of the engine. Flipping it would put it back up 'front' like the rwd. Does this have to do with heat crossover passages or EGR or something else I haven't thought of? If this is a problem, then install like fwd, with air intake from the back. There may not be enough room at the firewall for an elbow without modifying the intake. But that's doable. Could also use modified 84-85 hot air intake or 86-87 turbo intake.
7). I don't remember if the 86-87 heads have the same exhaust ports and could use the rwd exhaust or not. May have to mod rwd or fwd setup to get something to work.
With all this said, I don't think it would be much harder than this to make a 3800 series 1 work, either. Any other show stoppers you aware of?
Adios,
Brett
LOL... i hear you and this one. believe me DO NOT waste your time. i recently trash an input shaft, so the car is awaiting re-build tranny. my S/C 3800 make 415Hp with 534 Tq-Ft at the wheel woth a solid roller cam. I don`t see this motor make comparable Hp has the turbo Buick. the Eaton blower on the 3800 EAT`S hp.This 3800 motor is truly trouble free. i do not open the hood on my car unless i am install or removing a mod.
I must say the s/c motor drive very nicely no matter how must you mod it. feel`s like a heavy Mod V8. this car has NO lag. very hard too launch in the street due to different pavement condition.
you can also talk to AU guy this know some of them have this motor in a rear wheel drive
turbojustin,
Curiosity got the best of me today, so I took a closer look at an '86 fwd. I was wrong about the water passages in the intake. The 'front' passages are where they take in water from the heads. The 'rear' passages are blocked. When you look under the intake, you can see a runner underneath that pipes the water all the way to the back for the thermostat housing. Flipping the intake end for end would definitely draw water from the back of the heads. If this causes overheating, I suppose you could drill and tap the blocked passages and plumb water into the intake water passages externally and block off the other end. But it looks like the intake was designed to have hot water running under the floor to preheat the air, and changing the water flow may eliminate this.
Also, the oil filter housing sticks 'forward' next to the harmonic balancer. And I can't believe I forgot to look at the exhaust ports, but the heads are mucho different.
3800's not looking much worse.
Adios,
Brett
Curiosity got the best of me today, so I took a closer look at an '86 fwd. I was wrong about the water passages in the intake. The 'front' passages are where they take in water from the heads. The 'rear' passages are blocked. When you look under the intake, you can see a runner underneath that pipes the water all the way to the back for the thermostat housing. Flipping the intake end for end would definitely draw water from the back of the heads. If this causes overheating, I suppose you could drill and tap the blocked passages and plumb water into the intake water passages externally and block off the other end. But it looks like the intake was designed to have hot water running under the floor to preheat the air, and changing the water flow may eliminate this.
Also, the oil filter housing sticks 'forward' next to the harmonic balancer. And I can't believe I forgot to look at the exhaust ports, but the heads are mucho different.
3800's not looking much worse.
Adios,
Brett
87grandnat
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if you switch to front wheel drive how are you gonna pop wheelies
Red Regal T
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AGAIN.................
Originally posted by Red Regal T
It's been discussed before..........not feasible. Totally different motor. Different transmission bolt pattern, different crank etc. More GM help.
turbojustin
Ninja
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I think there may be some confusion as to what exactly I'm planning to do.
I have a 109 turbo longblock. I am planning to bolt on the intake and accessories (a/c, alternator, etc) from the FWD engine (85-87). I m not going to use any of the FWD mechanicals (crank, block, heads).
The engine is going to be bolted to a 200r4.
As far as I know, everything bolts up and this should work. My biggest concern is the coolant flow of the intake. Rather than spending atleast $1500 for the turbo specific accessories/intake, I should have somewhere closer to $500, AT MOST, for the FWD stuff.
Turbojustin,
I'm batting 1000 today. The bottom of the plenum is NOT heated. There's an air gap between the coolant passage and the plenum floor.
OK. First the intake. If you flip the intake, the throttle body may not clear the FWD alternator. If you install it as designed with the throttle body to the rear, it won't clear the firewall. I suppose you could modify the intake by welding an elbow and flange to the plenum and feeding it from the top/side and blocking off the original.
OK. Now the accessories. 85 fwd's are not serpentine and not gerotor pump. 86-87 fwd's are serpentine and gerotor oil pump, with a different front cover, harmonic balancer, lower pulley, etc. It would be a stroke of luck if the '86-87 front cover, gerotor pump, harmonic balancer, etc. would all bolt up to the rwd block and crank. But, all you really need is the bottom serpentine pulley to line up with the rest of the brackets.
I'm all ears if anybody knows what CAN work.
Adios,
Brett
I'm batting 1000 today. The bottom of the plenum is NOT heated. There's an air gap between the coolant passage and the plenum floor.
OK. First the intake. If you flip the intake, the throttle body may not clear the FWD alternator. If you install it as designed with the throttle body to the rear, it won't clear the firewall. I suppose you could modify the intake by welding an elbow and flange to the plenum and feeding it from the top/side and blocking off the original.
OK. Now the accessories. 85 fwd's are not serpentine and not gerotor pump. 86-87 fwd's are serpentine and gerotor oil pump, with a different front cover, harmonic balancer, lower pulley, etc. It would be a stroke of luck if the '86-87 front cover, gerotor pump, harmonic balancer, etc. would all bolt up to the rwd block and crank. But, all you really need is the bottom serpentine pulley to line up with the rest of the brackets.
I'm all ears if anybody knows what CAN work.
Adios,
Brett
turbojustin
Ninja
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Does this mean I can flip it without worries of overheating?
As far as the intake is concerned, I can MAKE it work. I already plan to cut off the plenum and then have it ported and welded back in place. I'm sure I can tweak it a little. If not, then I'll get the real turbo intake for about $150 used.
I think I've heard of people using the FWD front cover and water pump on turbo cars due to the greater efficiency of the FWD water pump. Correct me if I'm wrong. That would lead me to believe the accessories will line up.
Bottom line is I won't know until I try. Anyway, thanks for the help and info. I will keep you informed when things get going.
I guess you're trying to put the FWD intake and accesories on the 109 block. While I didn't do all this, I do have some insight.
I turned the stock GN intake backwards for the Metro and have no overheating problems. You will have to re-plumb your heater as it draws water from the intake and returns it to the water pump on the passenger side. The bypass is also at the front of the intake which will also be needing rework. I elminated mine and simply drilled an 1/8" hole in the thermostat itself to allow water to circulate and get the motor up to temp properly. You must do something to allow warming water on the thermostat spring for it to function properly. I have no overheating problems. As far as the motor drawing water from the back, that is actually better than the factory design, IMHO. Ever see a small block that had 4 corner cooling? Think about it, you're putting cooled water from the radiator in the front of the block and drawing it out immediately at the front of the heads. By tapping the water off at the back of the motor, you're forcing the water to circulate over all the cylinders before being sent to the radiator. You could always tap the front of the intake for 4 corner cooling if it proves to be a problem.
The later geo-rotor oil pump is why people like it, not the water pump. It is a fabricated ordeal. The front covers are not interchangeble to my knowledge. If they are, use a Ford radiator instead of a GM one, the inlets and outlets are reversed by sides. That would take care of that. The oil pan needs the front cut off and a new piece welded on where the later oil pump portion resides. Pretty simple though. Then you could use the stock GN oil pan and pickup. If you're interested, I could send you some pictures to better explain this. Be specific what you want, I've got plenty.
Why not just use the entire FWD motor?
I turned the stock GN intake backwards for the Metro and have no overheating problems. You will have to re-plumb your heater as it draws water from the intake and returns it to the water pump on the passenger side. The bypass is also at the front of the intake which will also be needing rework. I elminated mine and simply drilled an 1/8" hole in the thermostat itself to allow water to circulate and get the motor up to temp properly. You must do something to allow warming water on the thermostat spring for it to function properly. I have no overheating problems. As far as the motor drawing water from the back, that is actually better than the factory design, IMHO. Ever see a small block that had 4 corner cooling? Think about it, you're putting cooled water from the radiator in the front of the block and drawing it out immediately at the front of the heads. By tapping the water off at the back of the motor, you're forcing the water to circulate over all the cylinders before being sent to the radiator. You could always tap the front of the intake for 4 corner cooling if it proves to be a problem.
The later geo-rotor oil pump is why people like it, not the water pump. It is a fabricated ordeal. The front covers are not interchangeble to my knowledge. If they are, use a Ford radiator instead of a GM one, the inlets and outlets are reversed by sides. That would take care of that. The oil pan needs the front cut off and a new piece welded on where the later oil pump portion resides. Pretty simple though. Then you could use the stock GN oil pan and pickup. If you're interested, I could send you some pictures to better explain this. Be specific what you want, I've got plenty.
Why not just use the entire FWD motor?
Do a search for gerotor and you'll find Kendal Frederick's marriage of a gerotor lower half of the front cover to a stage II compatible upper, and discussion of what it would take to do it for a 109. You also have to modify either the crank or the lower timing gear to drive the pump.
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