Well first off I know that they are ODB1 and ODB2 respectivly. However, I noticed the intakes looks different and the power output is like 10hp more for the 96-97 than the 91-93 versions.
So, whats the skinny? Would it be possible to use a 96-97 engine and to use an ODB1 computer from a 91-93 version in a fiero? Anyone on here using the 96-97 engine have any feedback on this? Because I can find tons of 96-97 engines with low mileage compared to the 91-93 version.
yes you can run a 96-97 off the 91-93 computer and wiring as a MAP setup instead of MAF
just do a search on here for 3.4dohc and you'll find about everything you could ever want to know about this swap - there are several of us wrapping up our own 3.4 swaps
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03:21 PM
bigjoe25 Member
Posts: 266 From: cincinnati, oh Registered: Jan 2005
yes you can run a 96-97 off the 91-93 computer and wiring as a MAP setup instead of MAF
just do a search on here for 3.4dohc and you'll find about everything you could ever want to know about this swap - there are several of us wrapping up our own 3.4 swaps
I do search everytime before I post but I never can find anything. This search engine is a little different than ones Im used to. Anyway I found out the injector duty cycle is the only thing changed, so does that account for the extra 10hp?
hp on 96-97 is 215 i believe. the intakes are different. the 96-97 intakes have a removable tb. the 96-97 have different pistons, the heads are really different, 91-95 have hemi style combustion chambers the 96-97 have clover shaped chambers. the intake ports are the same but the exhaust port are larger and hence the exhaust manifolds are different too. the 91-95 cam banks use 35mm lifters i think but the 96-97 use 33mm lifters. other than that the only other thing worth mentioning is if u plan on changing cam timing stay away from 91-93 engines or swap out cam carriers with later years.
that is all i can think of off the top of my head. hope it helps
91-93 was MAP - batchfire multiport injection with the automatics having a 9.3:1 compression supposedly rated at 205hp
94-95 was the same as 91-93 excpet it went to MAF - sequential fuel injection and 9.5:1 compression rated at 210hp
96-97 it stayed MAF- SFI - but got new heads and intake , 9.7:1 compression, different cam timing that raised the peak hp by about 1000rpm to 205hp
those are the essentials.. the blocks are all the same and you can use the 91-93 wiring and computer to ruin all of them
Close again..
91-93 MPFI, MAP, autos had 9.25, manuals 9.5, 200hp/200tq for autos, 210hp/215tq sticks 94-95 SFI, MAF, 9.5, 210/215tq, also had a different alternator, cam sensor, and another crank sensor 96-97 had 225hp.
You can run an earlier MAP/MPFI ECU/harness on the later years, but be prepared to rewire the alternator.
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08:25 PM
Will Member
Posts: 14226 From: Where you least expect me Registered: Jun 2000
91-93 MPFI, MAP, autos had 9.25, manuals 9.5, 200hp/200tq for autos, 210hp/215tq sticks 94-95 SFI, MAF, 9.5, 210/215tq, also had a different alternator, cam sensor, and another crank sensor 96-97 had 225hp.
You can run an earlier MAP/MPFI ECU/harness on the later years, but be prepared to rewire the alternator.
While you're making corrections to other posts, if fair is fair, then I'm sure you won't mind the same. . Be advised that the hp on the 1997 LQ1 has it's peak horsepower at 5200 rpms where it makes 215 hp. The peak torque of 220 ft. lbs. is achieved at 4400 rpms. I know YOU didn't say the 96/97 engines make their power 1000 rpms higher than earlier engines but it's been repeated over and over until everyone thinks it has to be true because they've heard it so many times. Perhaps you might like to recheck those other engine figures also, they sound unusual.
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10:08 PM
Fierobsessed Member
Posts: 4782 From: Las Vegas, NV Registered: Dec 2001
91-93 MPFI, MAP, autos had 9.25, manuals 9.5, 200hp/200tq for autos, 210hp/215tq sticks 94-95 SFI, MAF, 9.5, 210/215tq, also had a different alternator, cam sensor, and another crank sensor 96-97 had 225hp.
You can run an earlier MAP/MPFI ECU/harness on the later years, but be prepared to rewire the alternator.
not to challenge your 3.4DOHC knowledge.. but you are the ONLY source i've seen of the 91-93 autos making 200hp or the 96-97 making 225.. everythign i've seen has rated the low compression at 205, mid at 210, and high at 215
and yes in 94 they added a cam sensor and another crank sensor because it used to run the SFI -
Originally posted by MikeW: Be advised that the hp on the 1997 LQ1 has it's peak horsepower at 5200 rpms where it makes 215 hp. The peak torque of 220 ft. lbs. is achieved at 4400 rpms.
thanks for the clarification - i've yet to see a dyno of a stock 96-97 so I was just going off what seemed to be "common knowledge" but we all know how accurate that can be
They are wrong about the 91's horsepower, unless they are using a 5-speed. We are sure about this, and a lot of magazines get it wrong.
As for my 96-97 stats beign wrong, yall are right I bet, I don't follow the newer ones too much.
The 5-speed cars had a stnadard AIR pump to reduce emissions, so obviously the bump in compression did something, and it accoutned for the higher hp and tq figures. THe -speed cars also got a standard water oil cooler.
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10:15 AM
MikeW Member
Posts: 158 From: Phoenix, Arizona U.S. Registered: Aug 2004
My source for the '97 dyno chart was from an acquaintance at the GM Mesa proving grounds. It came direct from the Gen Mot Powertrain Prod. Info book. I had asked for a dyno sheet or something that gave a series of hp and torque readings at various points. The graph I got isn't detailed and has been faxed and copied too many times to interpret. I'll have to assume Edmunds has the torque/rpm wrong and GM is right. Edmunds has lots of cars to cover and these errors inevitably happen. Anyone ever see actual dyno curves on the earlier engines? I believe ther's more to the 96/97 engines than just 5 more hp. I'll bet the later engines have more power across the curve. Too many positive changes for just 5 hp. Compression, thinner rings, better exhaust ports, revised upper and lower plenum. If they only got 5 more hp at 5200, I bet they picked up more along the way.
My source for the '97 dyno chart was from an acquaintance at the GM Mesa proving grounds. It came direct from the Gen Mot Powertrain Prod. Info book. I had asked for a dyno sheet or something that gave a series of hp and torque readings at various points. The graph I got isn't detailed and has been faxed and copied too many times to interpret. I'll have to assume Edmunds has the torque/rpm wrong and GM is right. Edmunds has lots of cars to cover and these errors inevitably happen. Anyone ever see actual dyno curves on the earlier engines? I believe ther's more to the 96/97 engines than just 5 more hp. I'll bet the later engines have more power across the curve. Too many positive changes for just 5 hp. Compression, thinner rings, better exhaust ports, revised upper and lower plenum. If they only got 5 more hp at 5200, I bet they picked up more along the way.
well that much is obvious since it hits peak torque 400rpm earlier and that peak is 5hp more.. just think area under the curve..
My source for the '97 dyno chart was from an acquaintance at the GM Mesa proving grounds. It came direct from the Gen Mot Powertrain Prod. Info book. I had asked for a dyno sheet or something that gave a series of hp and torque readings at various points. The graph I got isn't detailed and has been faxed and copied too many times to interpret. I'll have to assume Edmunds has the torque/rpm wrong and GM is right. Edmunds has lots of cars to cover and these errors inevitably happen. Anyone ever see actual dyno curves on the earlier engines? I believe ther's more to the 96/97 engines than just 5 more hp. I'll bet the later engines have more power across the curve. Too many positive changes for just 5 hp. Compression, thinner rings, better exhaust ports, revised upper and lower plenum. If they only got 5 more hp at 5200, I bet they picked up more along the way.
I also theorized about there being more HP in the later engines in a thread on here a long time ago. My thinking is, GM has many times in the past underrated engines to help out in the insurance department. Even the Fiero had this happen when they rated the 87-88 2.8's at a lower rpm so the HP looked like it was less. In the Fieros case it was 135HP in the 87-88 engines vs. the 140HP rating of the 85-86 2.8's. That's just one example too. GM has done this many times in the past on muscle cars especially so I would bet they did the same with the 96-97 TDC's. As you also said, there's just no way those engines could only be making 5 more HP with higher compression, better flowing heads, and better intakes. I'd also like to say that MikeW's comments about the power on the 96-97's being 400 rpm higher makes a lot more sense than the usual 1k higher claims that usually are made everywhere. Although the heads are better and especially the intakes, they aren't radically so different that you'd gain so much more rpm. 400 seems much more likely especially if you know anything about the LT1 vs LT4 V8 engines. A lot of similar changes made there to gain about the same rpm difference between the two engines. I must say that I have seen the 91-93 auto TDC's listed at 200HP like Aaron said. The 91-93 manual cars I've always seen listed as 210HP and the 94-95 I've always seen listed as 210HP. The 96-97's I've always seen listed as 215HP and 215 torque. Now whether that's all true or not I do not know but that's how I've seen them listed is all I'm saying. I had never seen ANY of them listed with 220 torque before this thread but that makes me just want a 96-97 even more! Great thread. Some good info in it.
no matter how well the intake and exhaust breath they are still limited by the cams - but it seems strange that they would do all that to give it more power than just give the 96 a performance cam upgrade and maybe an intake upgrade.. a completed top and redesign for 2 years? seems odd
no matter how well the intake and exhaust breath they are still limited by the cams - but it seems strange that they would do all that to give it more power than just give the 96 a performance cam upgrade and maybe an intake upgrade.. a completed top and redesign for 2 years? seems odd
That's true but all I'm saying is that those improvements would give more than 5HP. It doesn't mean they would give 40HP. All I'm saying, and what I think MikeW is saying, is that all those improvements would make more than 5HP gain on the newer motors even with the cams the same. Maybe 10 or 15 instead of 5 is all I'm talking about here. That can easily be done even with the cams staying the same. As for the complete top end redesign for only 2 years; that is dumb of Gm to do but it's right in character for them. Why would they redesign the 88 Fiero suspension,spending some 30 million in tooling, for only one year? I think, in a lot of ways, the TDC engine is a lot like the Fiero. I would bet GM had plans for it in the future but It is not an engine that most Lumina buyers would look for especially at the time. No offense meant to Luminas but they aren't exactly what I would call sporty and, in my opinion, the TDC needs to be in a small light sportscar. This motor really comes alive in a Fiero but there really wasn't anything like Fiero for GM to throw this engine in. Besides that, if Gm had made the TDC perform to it's potential, they certainly couldn't have a Lumina beating their sporty Z28's or right on the heels of their precious Vette. Oh well, another good idea by GM is killed yet the Aztec lives on.
yeah I hear ya - but we know the cams aren't timed the same.. and based on the peak torque being 400rpm lowe than the earlier engines i would say they de-tuned the engine for more low end to help with the automatic..
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02:09 PM
AaronZ34 Member
Posts: 2322 From: Colorado Springs, CO Registered: Oct 2004
Well the 96-97 made its max horsepower 500 LOWER than my 1992 Z34 did stock on the dyno. It also made max torque 100rpm lower. My Z34 made its max hp at 5600rpm, and max tq at 4100 rpm. So it seems like my midrange is stronger, which would make sense. But my car literally hits a brick wall at 6000, and it has only 100whp at 7000 rpm, whereas the 96 holds it to 6500 with only a minor dropoff to 7.
Everyone says the heads are more free-flowing, but there has been no evidence to suggest this, and even if they are, it has been proven that the stock heads on the earlier models are not a bottleneck. In fact, if the heads flow more, it could hurt performance, not help. More CFM doesn't always equal more power.
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05:22 PM
MikeW Member
Posts: 158 From: Phoenix, Arizona U.S. Registered: Aug 2004
I also theorized about there being more HP in the later engines in a thread on here a long time ago. My thinking is, GM has many times in the past underrated engines to help out in the insurance department. Even the Fiero had this happen when they rated the 87-88 2.8's at a lower rpm so the HP looked like it was less. In the Fieros case it was 135HP in the 87-88 engines vs. the 140HP rating of the 85-86 2.8's. That's just one example too. GM has done this many times in the past on muscle cars especially so I would bet they did the same with the 96-97 TDC's. As you also said, there's just no way those engines could only be making 5 more HP with higher compression, better flowing heads, and better intakes. I'd also like to say that MikeW's comments about the power on the 96-97's being 400 rpm higher makes a lot more sense than the usual 1k higher claims that usually are made everywhere. Although the heads are better and especially the intakes, they aren't radically so different that you'd gain so much more rpm. 400 seems much more likely especially if you know anything about the LT1 vs LT4 V8 engines. A lot of similar changes made there to gain about the same rpm difference between the two engines. I must say that I have seen the 91-93 auto TDC's listed at 200HP like Aaron said. The 91-93 manual cars I've always seen listed as 210HP and the 94-95 I've always seen listed as 210HP. The 96-97's I've always seen listed as 215HP and 215 torque. Now whether that's all true or not I do not know but that's how I've seen them listed is all I'm saying. I had never seen ANY of them listed with 220 torque before this thread but that makes me just want a 96-97 even more! Great thread. Some good info in it.
Please realize that I was correcting Koburns post from Edmunds specs. Edmunds said 4000 rpm torque peak and GM states 4400 rpm.
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08:12 PM
MikeW Member
Posts: 158 From: Phoenix, Arizona U.S. Registered: Aug 2004
I have not checked cam timing on the 96/97 engine. I do however have a brand new crate engine here and a degree wheel, dial indicator and adapters necessary to do the job. Before I get myself nominated for the job, I have to say that I've been sick for the last 12 days with a sinus infection and fever. I HAVE to get the Corvette going for a road race series I entered. Much time and $$ invested and I have parts to fabricate and I have to align the front and rear. I have plotted cam graphs and degreed cams since '74 so I'm capable. If enough people are intested, I can pursue this in the future. GM does changes usually so that it pays off in one way or another, not frivolously. If the cam timings in degrees of rotation vs. lift or total duration or something obvious shows the cam to be generally lesser than earlier cams, then one would assume a sacrice was made for peak rpm performance. I don't do cam analysis, there are highly sophisticated programs for that and I'm not referring to Desktop Dyno. This could be for emissions, mileage or drivability. The Luminas, Cutlasses and Monte Carlos could hav gotten heavier and overall driveability could have needed improvement. Hence adding a head design improvement and intake manifold tuning, both offering better flow would have picked up for cam loss. And gained 5 HP in the process. Now dont't tell everyone it's true because I just dreamed this up based on how products evolve as people get less interested in a model and the powertrain gets changed to "more for the masses". The 5 speed demand wasn't there and the auto people needed something that matched better. That would go along with my theory that the engine has more hidden uder the curve with that 5 more hp.
I could equally put up an argue ment for other scenarios. An actual dyno curve by GM of the earlier year engines could be helpful for comparison.. My Corvette has one in the owner's manual, I used to see them in the Ford truck literature showing comparison or the V6, 5.4 Triton, and V10. Has anyone EVER seen antything other than the 2 specs, peak torque/rpm and peak hp/rpm?
I posted the figues on the 97 engine originally in December (?) to stop the rumor that these engines produce their peak hp 1000 rpms higher than the past motors. The specs from GM confirm this.
this is kinda related but not really so i will apologize in advance. i couldn't resist after i have seen all the informed post on this thread.
recently my 96 motor went south and i am in need of a shortblock. 96-97 shortblocks are limited at best and i was wondering if i could use a 91-95 shortblock to bolt the 96 top end to? but i need to know somehow be4 i buy it, will the 96 heads work on it clearence-wise? i know there are some differences in piston design and i know it can be done the other way around.(91-95 top end on a 96 shortblock but u lose compression) if it can be done, can it be done to a 5spd motor? like i would actually find a 5spd shortblock. around here they are rarer than the 96-97 shortblocks.
i just don't have the funds to rebuild the 96 shortblock right now. b/c it probably needs to be overbored and i can get a shortblock for 75 bucks from this yard i know. i might keep it and build on it later or something.
p.s. on the cam discussion, i have heard that the 96-97 cam drive setups have a different number of teeth on them. i can't confirm or deny this though but if for some odd reason some1 wants to know, i suppose i could count them on my 96 motor.
[This message has been edited by dohcfiend (edited 04-22-2005).]
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10:11 PM
Apr 23rd, 2005
AaronZ34 Member
Posts: 2322 From: Colorado Springs, CO Registered: Oct 2004
Talk to Ben, he'd know for sure. If I were you dohcfiend, I'd buy a crate motor. You see them come up on Ebay every now and then. I paid $1200 for mine, and it runs PERFECT, smooth and yet very powerful for a stock 3.4
I don't have my graph with me, but I'll scan it up this May.
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12:16 AM
Fierobsessed Member
Posts: 4782 From: Las Vegas, NV Registered: Dec 2001
As far as I know, there is no differences between the blocks, and the pistons are close enough where it won't matter. the 2.4 CC's difference in the pistons will drop your compression from 9.7 down to 9.46, or 9.5 if you like round numbers (without whipping out the calculator, so I could be a smidge off, a CC is about 1 point in compression on a 3.4) Again, Im pretty sure you'll be ok mixing the years, just so long as cam gears and belt move togather (they changed in 96) everything should definatly match.
So I guess if I was making a list of changes for the 3 "generations" of the 3.4 DOHC Manuals available 284 Getrag 5 speed with pull type clutch (whatever that means ) 91-93 Automatic 4T60-E(HD) (91-96) Automatic 4T65-E (97 Z34 monte only) 16149396 OBD1 ECM 91-93 16196401 OBD1.5 ECM 94-95 OBD2 ECM 96-97 (cant find part #) A.I.R. on the manual equipt cars 91-93 Batch fire injection 91-93 SFI 94-97 standard GM DIS ignition system 91-97 3 coil style EGR 91-95 Digital EGR 96-97 "locking type" cam gears, that had to be pulled off with a puller tool 91-93 (iirc, because I've never seen one) tooth pitch was the same from 91-95 tooth pitch was changed for 96-97 Wedge type cam locks 94-97 Inline ports on the lower intake 96-97 Staggerd ports on the lower intake 91-95 intake with cast on throttle body 91-95 (has internal coolant passages) redesigned intake with removable throttle body 96-97 (has external coolant passages) Oil cooler (not sure, but 91-93? manual equiped cars only?) First design exhaust manifolds (can be two fronts for Fiero's) 91-95 Second design exhaust manifolds 96-97
Ive read in forum's that they changed the lifters, I dont think they actually did this. The transition from the Quad 4 to the TwinCam in 96 did see a lifter size change, and so did the Northstar some other time. (witch is an engine I don't have alot of info on so verify those claims elsewhere)
Edit: I do have to point out however, that since DOHCfiend PM'd me, he showed me a piston replacment catalog where two different pistons were listed, and one had a C.H. 1.458, the other 1.464 I measured my old 96 pistons and they had a C.H. of 1.476 not including the .040" dome. (I know how to use a dial caliper!) so in the end Im left with three different C.H. values and the only one I can believe is true is the one I measured first hand. Sigh... and it makes a big difference in compression and detonation resistance. Makes me wish I had a couple scrap engines to mic out. Anyone volunteer to mic the pistons up from 91-93, and 94-95's? Perhaps there different too? More reaseach...
[This message has been edited by Fierobsessed (edited 04-23-2005).]
i thought it was the other way around on the pistons/head interchange??? i thought if u put a 96 top end on a 91-95 short block compression would be higher and if u put a 91-95 top end on a 96-97 shortblock compression would be lower. or did i have it backwards? anyway which ever way it is, the valve/piston clearence won't be a problem then?
umm one of the changes i can verify is that the lifters did change in the 96-97 motors to a 33mm lifter vs the 35 i think in the earlier ones. and as far as i can tell it is identical to the N* lifters i sampled but i haven't weighed them against each other yet.(on the northstar i sampled it was a pre-96 vin y motor) i believe it is b/c of this that the springs are a little weaker in a 96 dohc. which also makes me wonder about putting 91-95 springs in as a cheap way to get more revs if i changed cam timing, or is the geometry different where they won't inerchange? on the oil cooler again i can't confirm or deny this but from what i "hear" it came on some auto's as an option. don't know about the 95-97 but on my 94 i noticed it didn't have the external tranny cooler either like on the 91-93 models and on the 94+ the rads were larger.
edit: so u think the other pistons listed in there were 5 speed pistons then? if not 96-97. ahh so based off of your specs there should be np other than compression loss. thanx.
[This message has been edited by dohcfiend (edited 04-23-2005).]
Edit: I do have to point out however, that since DOHCfiend PM'd me, he showed me a piston replacment catalog where two different pistons were listed, and one had a C.H. 1.458, the other 1.464 I measured my old 96 pistons and they had a C.H. of 1.476 not including the .040" dome. (I know how to use a dial caliper!) so in the end Im left with three different C.H. values and the only one I can believe is true is the one I measured first hand. Sigh... and it makes a big difference in compression and detonation resistance. Makes me wish I had a couple scrap engines to mic out. Anyone volunteer to mic the pistons up from 91-93, and 94-95's? Perhaps there different too? More reaseach...
Hey... I just discovered that an hour ago. I was contemplating whether I can slap a 96 spec piston into my 91/auto motor for some extra CR since I gotta rebuild. The two values that are available are the 1.458 + .040" dome for the "earlier" style piston (with earlier style rings), and the 1.464" + .040" dome for the "later" style piston. Tell you what though... looking at the piston sitting on my desk here from my auto motor - I don't think it has the dome. Unless I'm retarded, it appears dead flat with 4 valve reliefs. Auto motor = 9.25:1 CR, so it makes sense that the auto motors have a flattop piston instead of the dome. Sorry I can't help you any more than that. I put my digital caliper on the piston but I can only measure my CH as 1.4something", which isn't of use.
I'd buy a crate motor. You see them come up on Ebay every now and then. I paid $1200 for mine, and it runs PERFECT, smooth and yet very powerful for a stock 3.4
if i can't afford a rebuild, i sure as hell can't swing a crate motor. besides if i had $1200 to blow i could get a custom set of pistons(assuming the $75 per piston fee) using any compression i want, overbore the block to fit them, new bearings, rings and have it balanced with maybe 50-100 bux left over to spend.
blueshift, would u be interested in buying some 97-97 pistons to help the cause out? they will definately give u some compression in my motor the pistons(probably need new rings) are fine but the wall have to much clearence in them now for new rings so i can only overbore(according to the machine shop guy). i haven't measured it myself yet b/c every moment i get the time it rains . hell, if u were close enough, id sell the whole shortblock.
EDIT: i just found out the smaller lifters were on the 97 motors only. the 96er's have 35mm lifters like the previous. strange.
[This message has been edited by dohcfiend (edited 04-23-2005).]
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03:11 PM
PFF
System Bot
Apr 25th, 2005
Will Member
Posts: 14226 From: Where you least expect me Registered: Jun 2000
Originally posted by Fierobsessed: Ive read in forum's that they changed the lifters, I dont think they actually did this. The transition from the Quad 4 to the TwinCam in 96 did see a lifter size change, and so did the Northstar some other time. (witch is an engine I don't have alot of info on so verify those claims elsewhere)
Northstar lifters were the same through Y2K when they changed from flat tappet to roller. (33 mm)
Northstar lifters were the same through Y2K when they changed from flat tappet to roller. (33 mm)
hmmmmm. the roller ones are 33mm??? interesting indeed. b/c the machine shop said after doing a cam regrind id need either longer valves or taller lifters. and roller to boot, that is an added bonus. any1 know whether or not they would fit in a flat tappet cam bank or would the flat tappet cams work on them? i guess they could on a regrind maybe? some1 straighten me out on this be4 i get my hopes up.
omg a 3.4 dohc roller motor. that would be awesome.
[This message has been edited by dohcfiend (edited 05-01-2005).]
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05:41 PM
May 1st, 2005
Fierobsessed Member
Posts: 4782 From: Las Vegas, NV Registered: Dec 2001
Originally posted by dohcfiend: hmmmmm. the roller ones are 33mm??? interesting indeed. b/c the machine shop said after doing a cam regrind id need either longer valves or taller lifters. and roller to boot, that is an added bonus. any1 know whether or not they would fit in a flat tappet cam bank or would the flat tappet cams work on them? i guess they could on a regrind maybe? some1 straighten me out on this be4 i get my hopes up.
omg a 3.4 dohc roller motor. that would be awesome.
No, the roller valvetrain is completely different. I guess I should ahve said that the Northstar used the same lifters through '99... In Y2K it went to roller valvetrain. Alan Johnson shims the lifters when he does regrinds.
. hell, if u were close enough, id sell the whole shortblock.
