Sohc

D

Darkp71

Guest
Hello everyone. Ive always loved the mark viii however i know more about the sohc and like the lower compression engine.

Resently i was involved in an accident and i bought a high mileage 97 mark viii. The buying factors included the working HID lights, loud exhaust, and other small details.

The problem with it included the neon tail light doesn't work (seemed common), air bag issue due to a crack in the front bag, high miles, and paint issues.

I wasnt going to drive it long and didn't thanks to a 2nd purchase of a 04 crown Vic p71. However my vic now needs an engine that i plan to be a 5.4L sohc.

I have the mark viii in part out. However i would love to throw a sohc in it and only part out the engine.

Would this work?

I understand i would need a sct tuner and a custom tune. But anything else?

Engine mounts match up?
Headers line up?
Fuel system needs to use the sohc injectors? I may use a marauder 80 mm maf
Need the sohc oil pan?

Thanks in advanced
 
Yes, a SOHC 4.6L can be swapped in, but I don't know why you would want to. The engine mounts will line up. The headers or exhaust manifolds are completely different. You can use the SOHC or the DOHC fuel injectors, as either one will need to be accounted for in the tune, along with whatever MAF you choose to use. I'd keep the Mark 8 oil pan for its additional capacity.
 
Yea, I don't really see the appeal in doing a SOHC swap on a car that's already got a DOHC. The DOHC's are reliable, lightweight, and make more power than your run-of-the-mill SOHC, comparing stock to stock. If you wanted a SOHC, I would just pick up a 96-97 Cougar XR7 with all the bells and whistles. They're nice cars and can be optioned out ALMOST like a Lincoln, and it'd be easier than doing a swap. In my opinion, the swap would be alot of work and buying parts just to accomplish nothing positive I can think of. Of course, if it's something you really want to do, it is your car after all, and it would be unique. One thing I might recommend doing before you make up your mind is if you know anyone who has a 94 or newer MN12 T-Bird/Cougar, asking them to let you drive it. I've owned both a 95 T-Bird 4.6 and Mark VIII's, and there is a very noticeable power/performance difference between the two. Again, I'm not really trying to discourage you, but I don't want you to go through all the work and money necessary only to be disappointed. Good luck!
 
*Maverick* said:
Yea, I don't really see the appeal in doing a SOHC swap on a car that's already got a DOHC.
Click to expand...

There are much more high end engine mods (heads, intake, etc...) available for the SOHC vs. the b-headed DOHC is the only thing I can think of.
 
driller said:
There are much more high end engine mods (heads, intake, etc...) available for the SOHC vs. the b-headed DOHC is the only thing I can think of.
Click to expand...

Here's my buddy Russ. 2001 CVPI

crown vic 0-90 with built 4.6/highstall ....... - YouTube

13.41 NA
Low 12s on the shot

He recently put a custom set of longtubes on it from the BBK shorties that he was running. Should be good for 13.3xx I would think in good air.

That has also been done before on a SOHC in a big body Crown Vic:

13.35 @ 100 - YouTube

Here's that same Vic on a 125 shot:

World's fastest stock bottom end Crown Vic - YouTube


I've had the chance to peruse the Crown Vic forums and there are guys on there that are doing some crazy things with the SOHC. Both of these Vics in the video have Hitech Stage 2 cams which I think closes the gap in terms of rwhp compared to our 4-valves in NA form. Quickvic was at 286rwhp NA and Cameron was at around 300 rwhp NA.

Here is one more video when Cameron was in the beginning stages with his nitrous setup before he reduced some weight with the HVAC system and some other things.

Crown Vic in the 12s - YouTube
 
driller said:
There are much more high end engine mods (heads, intake, etc...) available for the SOHC vs. the b-headed DOHC is the only thing I can think of.
Click to expand...

Well that makes a little more sense to me now, then. But wouldn't doing a C-head/intake swap on the DOHC make it more versatile as well?
 
which after crunching the numbers, you mentioned c head swap which is what im planning.if you just look in history the96-98 cobra b head was 305hp, swap heads and intake next year went to 320 just in air flow.the cams i chose put up 385 in a 98 cobra in a mmff article, and the combo with the c heads and the mach 1 intake i plan on is around 400-410.i talked with a few local performance engine builders ,(im done with any regular mechanic), including sean hyland who stated with a full port job on the head and 98cobra intake (ported and polished as well) would move those #'s signifigantly. with a full port job on the marauder heads im going to leave the intake alone would jump the #'s high as well which is where you need to keep an eye on the strenghth of the shortblock. its really all in ho much you want to spend, where. you can spend 350-750 a pair on porting the heads, either style including backcutting the valves, etc, and cams, forget it i got a deal on mine but was still over $1000 for dohc. good luck finding a set under 1300 shipped or at a shop. ive already decided the route i want to take and should turn a few heads when its done in about a year.
the only "advantage" to the sohc motor is its cheaper. 2 cams instead of 4 and since it was the primary motor in mustangs theres a ton of stuff available for them, in mustangs. stay with 4v and let it breath if you look at the stock flow #'s in the heads and we'll use .400 lift since thats close to where the cams are, close measuring flow at .500 lift your motor will never see that unless you get a serious drag cam and most of the companies are offering lift max at .475 which is where i may go up to from .425, anyways intake
2v 96-98 gt...136cfm pi..153cfm 3v ...190.5 cfm 4v b 96-98 ...217 c99-01...218 03cobra...231cfm
exhaust
...................115cfm 123cfm 128.30 144cfm 143 163cfm
and those are stock #'s porting on b heads and 03-04cobra/mach 1 reveal really high flow #'s
sorry couldnt find the right flow #'s for the mach 1 but they are the same on marauder, mach 1,and aviator
had nothing else to do so .....
 
Is there anything wrong with the 4V in it now? I don't see the point of going through the effort unless the existing motor has issues. While Driller does have a point to a degree it's over $1000 for for TF heads. Your CVPI isn't much heavier then a Mark and you should be able to tell what a difference it is driving both.

the1andonlyGR81 said:
which after crunching the numbers, you mentioned c head swap which is what im planning.if you just look in history the96-98 cobra b head was 305hp, swap heads and intake next year went to 320 just in air flow.the cams i chose put up 385 in a 98 cobra in a mmff article, and the combo with the c heads and the mach 1 intake i plan on is around 400-410.i talked with a few local performance engine builders ,(im done with any regular mechanic), including sean hyland who stated with a full port job on the head and 98cobra intake (ported and polished as well) would move those #'s signifigantly. with a full port job on the marauder heads im going to leave the intake alone would jump the #'s high as well which is where you need to keep an eye on the strenghth of the shortblock. its really all in ho much you want to spend, where. you can spend 350-750 a pair on porting the heads, either style including backcutting the valves, etc, and cams, forget it i got a deal on mine but was still over $1000 for dohc. good luck finding a set under 1300 shipped or at a shop. ive already decided the route i want to take and should turn a few heads when its done in about a year.
the only "advantage" to the sohc motor is its cheaper. 2 cams instead of 4 and since it was the primary motor in mustangs theres a ton of stuff available for them, in mustangs. stay with 4v and let it breath if you look at the stock flow #'s in the heads and we'll use .400 lift since thats close to where the cams are, close measuring flow at .500 lift your motor will never see that unless you get a serious drag cam and most of the companies are offering lift max at .475 which is where i may go up to from .425, anyways intake
2v 96-98 gt...136cfm pi..153cfm 3v ...190.5 cfm 4v b 96-98 ...217 c99-01...218 03cobra...231cfm
exhaust
...................115cfm 123cfm 128.30 144cfm 143 163cfm
and those are stock #'s porting on b heads and 03-04cobra/mach 1 reveal really high flow #'s
sorry couldnt find the right flow #'s for the mach 1 but they are the same on marauder, mach 1,and aviator
had nothing else to do so .....
Click to expand...

Comparing apples to apples between a Mustang and a Mark isn't going towork as some o the guys like Driller would tell you. Still ported C heads, intake and cams should be 350rwhp all day long in a stang. I don't think you will see that in the Mark without aggressive cams and ported intake.
 
From what i can tell no one has answered this yet. Its not a matter of why. Its a matter of yes or no and how.

First off. Lets play the what if game.

What if the engine blows up?
Dohc- you'll need an engine used in only 3 cars and pay 1000 if you're lucky.
Sohc- what didnt use it? Its 500 for a fair mileage

What if i want to use a different octane?
Dohc- you cant go down and 93 is the highest fuel octane.
sohc- tune. Done

Not saying the dohc isnt great but i dont think i ever asked opinions about which is the better engine.
 
Rich88LSC said:
Is there anything wrong with the 4V in it now? I don't see the point of going through the effort unless the existing motor has issues. While Driller does have a point to a degree it's over $1000 for for TF heads. Your CVPI isn't much heavier then a Mark and you should be able to tell what a difference it is driving both.



Comparing apples to apples between a Mustang and a Mark isn't going towork as some o the guys like Driller would tell you. Still ported C heads, intake and cams should be 350rwhp all day long in a stang. I don't think you will see that in the Mark without aggressive cams and ported intake.
Click to expand...

I can tell the difference.

My 3.55 gears in my 00 with 225 hp would rape the mark
And my 04 cvpi has made the marauder at the drag strip wonder why he paid so much for the extra cams.

The two issues you fail to understand is sohc has a better torque curve and the crown vics use better stock gearing.

In this case, you my friend are comparing apples and oranges.


I would need to drive a 04 cvpi with a mark VIII with better gears
 
Darkp71 said:
What if i want to use a different octane?
Dohc- you cant go down and 93 is the highest fuel octane.
sohc- tune. Done
Click to expand...

run 89 in my car all the time. with a chip on top of the most aggressive computer they put in a mark. no issues at all.
 
Darkp71 said:
What if the engine blows up?
Dohc- you'll need an engine used in only 3 cars and pay 1000 if you're lucky.
Sohc- what didnt use it? Its 500 for a fair mileage
Click to expand...


the DOHC engine is in marks, mustangs, mach 1 and cobra, aviator suvs, and some weird stuff. a panoz, mg, etc. more than 3 cars. but yeah, i would assume they are more expensive.
the mark does have the rare and strong Teksid aluminium block though.

but just don't blow it up. i've made it 192k miles and haven't had that problem.
 
Darkp71 said:
I can tell the difference.

My 3.55 gears in my 00 with 225 hp would rape the mark
And my 04 cvpi has made the marauder at the drag strip wonder why he paid so much for the extra two issues you fail to understand is sohc has a better torque curve and the crown vics use better stock gearing.

In this case, you my friend are comparing apples and orang
I would need to drive a 04 cvpi with a mark VIII with better gears
Click to expand...

What?
Show me your better torque curve
Show me a stock cv betting a stock mark (both running good)
And better stock gearing being we both have the same gears in the trans that leaves
A wopping difference of 3.27 to 3.55's woho.
You question was answered post #5
 
O and the what if it blows up
You can buy a whole running driving mark for under $1000
Just picked up a mark motor for a friend for $250
The yard by me has 3 at $226 each.
You can tune the car to run on 87 if you want also.
 
The real question is what if you ran a mark viii engine with 2v pi heads and intake? From what I've read it ups the compression to around 10:1 and is still light weight.
 
Blckcobra said:
The real question is what if you ran a mark viii engine with 2v pi heads and intake? From what I've read it ups the compression to around 10:1 and is still light weight.
Click to expand...

PI 2V heads on a stock TEKSID shortblock yields ~11.7-11.8:1 CR.
 
I heard rumors of a T-bird running a Teksid with 2-valve PI heads and I think the car was running 12s all motor. I couldn't find any documentation of it, but he told me the car exists. That's pretty good times NA in a somewhat heavy car.
 
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