SOHC Vs. DOHC??? Some question...

4-Cyl. Technical/Performance Discussions
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Surgeonasst222
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SOHC Vs. DOHC??? Some question...

Post by Surgeonasst222 »

Well I just bought a 92 RS and it had some engine problems, there is a oil leak somewhere... I didn't look into that cuz I know the top end is bad. I was going to get that rebuilt for like $300 but someone kind of talked me into saving up for a full engine rebuild now that's about $1900.

While I was looking for more people that rebuild engines, and I found a guy that will replace my engine for another engine that is from a junk yard and try to get it with low miles. This would cost me $300-$500... So I used to have a 94 RS with a DOHC, I don't know the differences and thought maybe I could that engine instead.

So I have many questions here as I am a noob to this stuff.

1. Should I just do the top end rebuild?
2. Should I save for the full rebuild?
3. Should I just get a different engine with low miles from a junk yard?
4. If I should do number 3, should I get the same engine or a DOHC engine?
5. Is that even possible, if so what are the advantages if I do?
6. Is there even a difference between the 2?

Thanks in advance,

Kegan
Mazda3 2012 - my NEW DD :mrgreen:
Mazda MX-3 RS 1992 - my project
Ford Focus SE 2010 - sold
Ford Focus SE 2003 - sold

Mazda MX-3 RS 1994 - sold :(
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kulluminati777
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Re: SOHC Vs. DOHC??? Some question...

Post by kulluminati777 »

if i was in your shoes i would do number 3 and get the a DOHC 4cyl with a tad bit more power....
View my worklog: viewtopic.php?f=46&t=77688
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Re: SOHC Vs. DOHC??? Some question...

Post by Surgeonasst222 »

kulluminati777 wrote:if i was in your shoes i would do number 3 and get the a DOHC 4cyl with a tad bit more power....
As I have a SOHC now can they just pop out that one and pop in a DOHC with no problems? I don't want to put in hundreds more just for stuff to work.

Thanks,
Mazda3 2012 - my NEW DD :mrgreen:
Mazda MX-3 RS 1992 - my project
Ford Focus SE 2010 - sold
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Mazda MX-3 RS 1994 - sold :(
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Re: SOHC Vs. DOHC??? Some question...

Post by kulluminati777 »

im 99.9999% sure the only thing extra you would need would be the ECU but im a V6. I would wait until i 4cyl guy gets online and comments to pull the trigger
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Re: SOHC Vs. DOHC??? Some question...

Post by Savin »

Swap in a BP engine. Its plug-n-play for the SOHC engine. To swap to the DOHC B6, you'd have to change the whole engine harness as well.
'95 MX-3 RS - Project "Déjà Vu" Destined for the scrapyard.
'93 MX-3 GS - SOLD!
'93 MX-3 GS SE - Parts car!
'94 MX-3 GS - Scrapped
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'96 Sunfire SE - Scrapped
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Re: SOHC Vs. DOHC??? Some question...

Post by kulluminati777 »

oh i thought the BP was DOHC?
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Re: SOHC Vs. DOHC??? Some question...

Post by Savin »

The BP is DOHC. But it uses a VAF like the SOHC B6 whereas the DOHC B6 uses a MAF.

There's other differences I'm sure. But the BP is the engine you want if you're going to swap. There is much info about the swap in the 4cyl FAQ and peoples' worklogs.
'95 MX-3 RS - Project "Déjà Vu" Destined for the scrapyard.
'93 MX-3 GS - SOLD!
'93 MX-3 GS SE - Parts car!
'94 MX-3 GS - Scrapped
'94 MX-3 RS - Scrapped
'96 Sunfire SE - Scrapped
'03 Sunfire SE - Deathtrap
'95 Cavalier Base - Scrapped
'94 Thunderbird LX - Collects dust
'89 Mustang GT - SOLD!
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Surgeonasst222
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Re: SOHC Vs. DOHC??? Some question...

Post by Surgeonasst222 »

Savin wrote:The BP is DOHC. But it uses a VAF like the SOHC B6 whereas the DOHC B6 uses a MAF.

There's other differences I'm sure. But the BP is the engine you want if you're going to swap. There is much info about the swap in the 4cyl FAQ and peoples' worklogs.
Lol ok I said noob here so what do I need to ask for when I go to this guy and point me at a work log that talks about this and I will be happy man! I don't really want this to be a hassle, I want this not to be a big deal. Is the SOHC really that much of a dog I will hate myself for not doing this other DOHC? Like I said I just want to plug and play, if I want to bump up to this bp DOHC how much extra money am I talking here.

Thanks much Savin
Last edited by Surgeonasst222 on February 20th, 2013, 10:53 pm, edited 1 time in total.
Mazda3 2012 - my NEW DD :mrgreen:
Mazda MX-3 RS 1992 - my project
Ford Focus SE 2010 - sold
Ford Focus SE 2003 - sold

Mazda MX-3 RS 1994 - sold :(
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Re: SOHC Vs. DOHC??? Some question...

Post by Surgeonasst222 »

Double post sry :(

:s
Mazda3 2012 - my NEW DD :mrgreen:
Mazda MX-3 RS 1992 - my project
Ford Focus SE 2010 - sold
Ford Focus SE 2003 - sold

Mazda MX-3 RS 1994 - sold :(
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Re: SOHC Vs. DOHC??? Some question...

Post by Savin »

SOHC B6 - 88hp
DOHC BP - 130hp

If the engine is from a junkyard or where ever, then it should cost about the same (plus the bp computer and matching VAF) those both plug right in though.

Read this: http://www.mx-3.com/phpBB3/viewtopic.php?f=3&t=38979 It'll give you a ton of info.
'95 MX-3 RS - Project "Déjà Vu" Destined for the scrapyard.
'93 MX-3 GS - SOLD!
'93 MX-3 GS SE - Parts car!
'94 MX-3 GS - Scrapped
'94 MX-3 RS - Scrapped
'96 Sunfire SE - Scrapped
'03 Sunfire SE - Deathtrap
'95 Cavalier Base - Scrapped
'94 Thunderbird LX - Collects dust
'89 Mustang GT - SOLD!
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Re: SOHC Vs. DOHC??? Some question...

Post by RobMinhas »

That thread is a little difficult to go through without a decent amount of car knowledge so I'll try to give you some help here.

What you'll need:

A Mazda/Ford BP engine(90-94 Mazda Protege with the DOHC and 90-93 Ford Escort GT, Im not 100percent sure on the years for the Escort though).
BP VAF from the same car the engine came from.
BP ECU from the same car you pulled the engine from

That's it, you don't need any harness bits or anything, pull out, stuff in, bolt up and plug in. Any mechanic worth their salt can do this swap.

Id reccomend doing the timing belt and water pump as well as replace the clutch since those jobs are incredibly easy when the engines out.

A guide i used when I researched my swap(other then picking at Mi|<es brain) was this site here:

http://www.clubprotege.com/wil/tech/b-s ... wapfaq.htm
Daninski wrote:This is my MX3. There are many like it, but this one is mine. My MX3 is my best friend. It is my life. I must master it as I master my life. My MX3, without me, is useless. Without my MX3, I am useless. I must fire up my MX3 true. I must drive straighter than any Honda driver who is trying to own me. I must own him before he owns me.
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Re: SOHC Vs. DOHC??? Some question...

Post by Surgeonasst222 »

RobMinhas wrote:That thread is a little difficult to go through without a decent amount of car knowledge so I'll try to give you some help here.

What you'll need:

A Mazda/Ford BP engine(90-94 Mazda Protege with the DOHC and 90-93 Ford Escort GT, Im not 100percent sure on the years for the Escort though).
BP VAF from the same car the engine came from.
BP ECU from the same car you pulled the engine from

That's it, you don't need any harness bits or anything, pull out, stuff in, bolt up and plug in. Any mechanic worth their salt can do this swap.

Id reccomend doing the timing belt and water pump as well as replace the clutch since those jobs are incredibly easy when the engines out.

A guide i used when I researched my swap(other then picking at Mi|<es brain) was this site here:

http://www.clubprotege.com/wil/tech/b-s ... wapfaq.htm
Thanks man you answered some of the questions I had after reading that long thread! Also I want to try and do this swap by myself it is the main reason I got this car was to learn more how to do car stuff and I think this sounds pretty easy for swapping a engine... I will also look at doing both of those things while I am in there.

My last question is most of what I was reading in there seemed to be for manual tranny. I have a automatic tranny is there any differences that I need to be aware of and should I do a flush and filter change while the engine is out?

When it turns spring I start a work log on all of this... When I start... My house doesn't have a garage and my dad has spare space so it will go there when spring comes!

Thanks guys for the help!!!
Mazda3 2012 - my NEW DD :mrgreen:
Mazda MX-3 RS 1992 - my project
Ford Focus SE 2010 - sold
Ford Focus SE 2003 - sold

Mazda MX-3 RS 1994 - sold :(
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Re: SOHC Vs. DOHC??? Some question...

Post by RobMinhas »

It's supposed to be stupidly easy to do the swap assuming you don't run into seized/broken bolts. Borrow a hoist and you should be set, helps to have some buddies who can help wrench.

As far as auto trans....I really don't know if the auto from the b6 will bolt up to the bp, I would imagine it does but I don't know for sure.
Daninski wrote:This is my MX3. There are many like it, but this one is mine. My MX3 is my best friend. It is my life. I must master it as I master my life. My MX3, without me, is useless. Without my MX3, I am useless. I must fire up my MX3 true. I must drive straighter than any Honda driver who is trying to own me. I must own him before he owns me.
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Re: SOHC Vs. DOHC??? Some question...

Post by Savin »

It'll bolt up fine. ...but it won't last long if you drive the car hard. The auto transmissions in these cars aren't exactly strong. They barely manage to handle stock power.
'95 MX-3 RS - Project "Déjà Vu" Destined for the scrapyard.
'93 MX-3 GS - SOLD!
'93 MX-3 GS SE - Parts car!
'94 MX-3 GS - Scrapped
'94 MX-3 RS - Scrapped
'96 Sunfire SE - Scrapped
'03 Sunfire SE - Deathtrap
'95 Cavalier Base - Scrapped
'94 Thunderbird LX - Collects dust
'89 Mustang GT - SOLD!
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Surgeonasst222
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Re: SOHC Vs. DOHC??? Some question...

Post by Surgeonasst222 »

Savin wrote:It'll bolt up fine. ...but it won't last long if you drive the car hard. The auto transmissions in these cars aren't exactly strong. They barely manage to handle stock power.
Ok sounds great at least I know it works! Also car only has 79k on it with only one owner before me and besides the engine it is in good shape... The inside is dirty but a solid weekend of cleaning will do her good. Need some new seats thoe. Guy was a college kid, doubt he had the money or the time to deal with it.

I will plan on this in the spring!

Thanks again guys!
Mazda3 2012 - my NEW DD :mrgreen:
Mazda MX-3 RS 1992 - my project
Ford Focus SE 2010 - sold
Ford Focus SE 2003 - sold

Mazda MX-3 RS 1994 - sold :(
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