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3.4 dohc with a 4 speed? by Four_hundred_86
Started on: 06-29-2014 06:50 PM
Replies: 21 (444 views)
Last post by: chetw77cruiser on 07-01-2014 02:35 PM
Four_hundred_86
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Report this Post06-29-2014 06:50 PM Click Here to See the Profile for Four_hundred_86Click Here to Email Four_hundred_86Send a Private Message to Four_hundred_86Edit/Delete MessageReply w/QuoteDirect Link to This Post
Has anyone ever coupled a 3.4 dohc to a factory 85-86 4 speed? The even spacing of the gears seems like it would work really well the 7k red line of the engine.

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Honestly, What is a "stock" Fiero?

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chetw77cruiser
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Report this Post06-29-2014 08:22 PM Click Here to See the Profile for chetw77cruiserSend a Private Message to chetw77cruiserEdit/Delete MessageReply w/QuoteDirect Link to This Post
Where, I mean when are you getting the engine? I know where there is one for cheap.
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dobey
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Report this Post06-29-2014 09:30 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
I've seen it mated to the Isuzu 5 speed. I don't think you'd want that 4 speed if you intend to drive it on the highway, though. The 84 econo 4 speed will give the lowest highway RPM. The 84 performance 4 speed will have the best acceleration. The 85-86 4 speed is not the best for either one. The 5 speeds are both better for accelration and highway RPM than the 85-86 4 speed is.
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ltlfrari
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Report this Post06-29-2014 11:15 PM Click Here to See the Profile for ltlfrariClick Here to visit ltlfrari's HomePageClick Here to Email ltlfrariSend a Private Message to ltlfrariEdit/Delete MessageReply w/QuoteDirect Link to This Post
I assume you mean a stick (I can never tell these things).
I had a dohc mated to an issuzi 5 speed, 70 mph = 2400 rpm, put you foot down, even at 70 and it just went!
Only down side was the spacing of 1st to 2nd was too big for my liking. I could be doing 35 in first, change to 2nd and by the time I got it in gear the revs had dropped way off but otherwise it was a great fit.

I currently have an 85 v6 with a 4 speed stick, 70 mph = 3000 rpm = way too busy (ie noisy) on the highway for any length of time but around town I would think it would be ok with dohc because of the better spacing of the rations and no oportunity to go that fast.

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Anything I might say is probably worth what you paid for it, so treat it accordingly!

Dave

www.ltlfrari.com

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Four_hundred_86
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Report this Post06-29-2014 11:18 PM Click Here to See the Profile for Four_hundred_86Click Here to Email Four_hundred_86Send a Private Message to Four_hundred_86Edit/Delete MessageReply w/QuoteDirect Link to This Post
Why? If I may be as so bold. My 4 speed is decent for highway on the 2.8 I manage between 24-27 highway mpg. Also I want acceleration over economy.
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MstangsBware
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Report this Post06-29-2014 11:30 PM Click Here to See the Profile for MstangsBwareClick Here to Email MstangsBwareSend a Private Message to MstangsBwareEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Four_hundred_86:

Why? If I may be as so bold. My 4 speed is decent for highway on the 2.8 I manage between 24-27 highway mpg. Also I want acceleration over economy.


Just buy the 88 Formula I have for sale with the DOHC/Getrag already installed and call it a day...
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Four_hundred_86
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Report this Post06-29-2014 11:50 PM Click Here to See the Profile for Four_hundred_86Click Here to Email Four_hundred_86Send a Private Message to Four_hundred_86Edit/Delete MessageReply w/QuoteDirect Link to This Post
Isn't that kind of like cheating? Is it still for sale?
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MstangsBware
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Report this Post06-30-2014 02:04 AM Click Here to See the Profile for MstangsBwareClick Here to Email MstangsBwareSend a Private Message to MstangsBwareEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Four_hundred_86:

Isn't that kind of like cheating? Is it still for sale?


Yes its still for sale with or without the Held suspension.. Look Iin the Mall for the CL add with details and pics.
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fireboss
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Report this Post06-30-2014 03:10 AM Click Here to See the Profile for firebossClick Here to Email firebossSend a Private Message to firebossEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by MstangsBware:


Yes its still for sale with or without the Held suspension.. Look Iin the Mall for the CL add with details and pics.


Wished it had A/C
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dobey
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Report this Post06-30-2014 10:14 AM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Four_hundred_86:

Why? If I may be as so bold. My 4 speed is decent for highway on the 2.8 I manage between 24-27 highway mpg. Also I want acceleration over economy.


The 85-86 4 speed is not the best for either acceleration, or economy. It's a middle of the road trans. The Getrag 5 speed is probably the best of the stock Fiero manual transmissions for what you want.
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Will
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Report this Post06-30-2014 01:44 PM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by dobey:


The 85-86 4 speed is not the best for either acceleration, or economy. It's a middle of the road trans. The Getrag 5 speed is probably the best of the stock Fiero manual transmissions for what you want.


The 85-86 unit is the strongest of the 4 speeds due to extra reinforcement of the case. I don't think the 4 cylinder case is a good idea to use with an uprated engine.
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Report this Post06-30-2014 04:35 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Will:


The 85-86 unit is the strongest of the 4 speeds due to extra reinforcement of the case. I don't think the 4 cylinder case is a good idea to use with an uprated engine.


Sure. I don't think any of the stock Fiero transmissions are rated to handle the more powerful engines that people are swapping in. Is the 85-86 4 speed stronger than the Getrag though? Unless one really wants to stick with the 4 speed, the Getrag might be a better option, for both acceleration and highway cruising.

Though if one wants to hop out of the simple bolt-in realm, the F23 is probably an even better option.
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MstangsBware
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Report this Post07-01-2014 01:29 AM Click Here to See the Profile for MstangsBwareClick Here to Email MstangsBwareSend a Private Message to MstangsBwareEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fireboss:


Wished it had A/C


That makes 2 of us. I wouldn't sell it if it did and tthinking if it doesn't sell to take the time to add AC..It's just that fun of a car to drive..
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Will
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Report this Post07-01-2014 09:47 AM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by dobey:


Sure. I don't think any of the stock Fiero transmissions are rated to handle the more powerful engines that people are swapping in. Is the 85-86 4 speed stronger than the Getrag though? Unless one really wants to stick with the 4 speed, the Getrag might be a better option, for both acceleration and highway cruising.

Though if one wants to hop out of the simple bolt-in realm, the F23 is probably an even better option.


Maybe OP *HAS* a 4 speed and would have to spend more money on a different trans...
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Four_hundred_86
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Report this Post07-01-2014 10:27 AM Click Here to See the Profile for Four_hundred_86Click Here to Email Four_hundred_86Send a Private Message to Four_hundred_86Edit/Delete MessageReply w/QuoteDirect Link to This Post
Will! You are correct, I have a 86 sent 4speed, and was looking to see if someone had put this together like that.
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dobey
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Report this Post07-01-2014 10:48 AM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Will:
Maybe OP *HAS* a 4 speed and would have to spend more money on a different trans...


Then OP can use it if he wants. I was just providing the information on which ratios in the stock Fiero manual transmissions match up best with acceleration and how the 85-86 4 speed compares to them.

I never said he couldn't bolt it up. I don't know of any swap that has used that trans with the DOHC (which is what he asked), but there's no reason it wouldn't work. I do know the Isuzu and Getrage have been used, and they are better matches for the engine.
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Four_hundred_86
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Report this Post07-01-2014 10:51 AM Click Here to See the Profile for Four_hundred_86Click Here to Email Four_hundred_86Send a Private Message to Four_hundred_86Edit/Delete MessageReply w/QuoteDirect Link to This Post
Thank you dobey, I appreciate the input. I haven't a ton of money for this swap, I can get an engine fairly cheaply, was just wondering if / how well the unit would drive out without swapping to a 5 speed. I like the idea of it, but that adds a considerable amount to the cost of the swap
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Report this Post07-01-2014 01:11 PM Click Here to See the Profile for Silicoan86Click Here to Email Silicoan86Send a Private Message to Silicoan86Edit/Delete MessageReply w/QuoteDirect Link to This Post
It has been done before.

The Getrag is obviously the best option, but IMO the Muncie 4-speed should work just fine behind a 3.4 DOHC. It's biggest flaw is, of course, highway cruising RPM. If that doesn't bother you with the stock 2.8 V6, it probably won't bother you much more with the 3.4 DOHC except for a possibly louder exhaust note (depending on how you build your exhaust system).

I have a 3.4 DOHC mated to an Isuzu. While highway cruising RPM is great, the very long second gear leaves a lot to be desired. I have acquired a Getrag 282 that will be going in later this year.
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dobey
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Report this Post07-01-2014 01:43 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Four_hundred_86:

Thank you dobey, I appreciate the input. I haven't a ton of money for this swap, I can get an engine fairly cheaply, was just wondering if / how well the unit would drive out without swapping to a 5 speed. I like the idea of it, but that adds a considerable amount to the cost of the swap


The stock 4 speed should be fine. Depending on how your current clutch looks, you might want to replace it while doing the swap. With the DOHC you'll get almost 3000 RPM more usefulness out of each gear compared to the 2.8, though you might end up rowing through the gears faster than with the 2.8, because the 3.4 makes a bit more power.
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chetw77cruiser
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Report this Post07-01-2014 02:07 PM Click Here to See the Profile for chetw77cruiserSend a Private Message to chetw77cruiserEdit/Delete MessageReply w/QuoteDirect Link to This Post
Then it is settled. Come get your darned engine Chance, gaskets, bolts, and all.

Consider it a wedding gift.
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phonedawgz
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Report this Post07-01-2014 02:14 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Depending on the year the ECM needs a clutch switch input.
Also some years they didn't mate the DOHC with a MT so you can't get an ECM factory programmed for the MT.
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chetw77cruiser
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Report this Post07-01-2014 02:35 PM Click Here to See the Profile for chetw77cruiserSend a Private Message to chetw77cruiserEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have a 16149396 that will go with this engine, that is unless he wants to stay with the 7165 that is in his car already.
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