Loginology

Hi guys. I want to put in a turbo eventually, but I have the 1.8L SOHC and not DOHC BP engine. I want to upgrade to the DOHC in order to be able to add the turbo in a few months. I also want the horsepower gains it provides to somewhat settle my need for more speed untill I can afford the turbo.

What all is involved in changing the SOHC to DOHC? From what I read, all I need to do is change the head to a DOHC head and get an ECU from a DOHC. Is there anything else that I'll need to do?

zenilder

So far I've noted that if I were to swap the head, rather than swaping the entire engine for a DOHC, I would need the water pump, distributor, fuel rail harness, fuel rail mount bracket and gromets, intake manifold from a DOHC with VICS assembly and TB, one extra pressure regulator solenoid (for VICS), exhaust manifold, new timing belt, timing belt cover, ECU, and a couple of different water hoses that run behind the engine and under the intake manifold. As for the wiring harness, I've been told that you need the one from an LX or EGT. I haven't verified if you can still use the DX ECU with the fuel rail wiring harness from the LX. The wiring harness from the LX includes the connectors for controling the VICS pressure regulator solenoid. I don't remember what the male/female connector for that particular harness looks like on the DX. I can check tonight when I get home and compare the fuel rail wiring harness I picked up from the yard to the one in my car. Not to mention that you would need new head bolts, as the ones that come stock in our cars are one-time use bolts. They stretch when you torque them down, so I've been told. I'd replace the head gasket at the same time.

Yeah, like Jesse said, you'll need to replace the tranny. If you can find a tranny from an LX from a yard, grab it. Your Fseries box that you have now will eventually fail. I run my car pretty hard here and there, and my box is already starting to show signs of failing, vibrating/grinding--hard to discribe--around 3k and for just a bit above in all gears. Course it might be a combination of engine mounts/hermonics.

Anyways, I was going to do the same thing as you, but I landed up getting a hold of a DOHC longblock. I'm just going to swap it all in. Though, there are still little things here and there have to get for it to be complete.


Later on.

Loginology

pffft....basically, just get a BPT engine like I was origionally gonna do...

Loginology

heh...so you're mad at me for being a jerk to myself? I'm the one that made the origional post...I was saying "pffft" as in "well never mind" and "buy a BPT like I was origionally going to do" as in "I'll just buy that BPT, I thought this would be easier but I gues not"

check the person posting from now on

Loginology

I want to boost the hell out of my car. I heard you can get 400hp out of them without having to redo the guts of the engine, as long as you have the ***** to run that much boost. Well, I wont be even partially satisfied till I get atleast 250hp....but I want to get as much HP out of it as possible, even if it means it takes me 4 years.

protejay

installing SOHC pistons in a DOHC results in lower compression - about 8.2:1 ....so for boost, puttin the DOHC head on your SOHC may be better!??

zenilder

heh. sorry about that, dude. didn't really pay attention. I was in a bit of a hurry here at work, too, as well as angry about a matter regarding work. so, I was kind of quick to react.

If you were orignially going to put in the BPT, then why are you no longer going to do it? You thought it might be easier/cheaper to put in the DOHC?

zenilder

...And if you're going to get a custom exhaust mani, might as well stick with the SOHC, it has lower compression. It was something I was thinking about at one time.
Like Jesse said, stand alone would be your best bet to rip as much power out of the engine. A little fuel piggyback computer will eventually reach it's limit. With that route, it would prolly be a good idea to get some new injectors, too.

zenilder

I would believe the 16-valve SOHC flows the same as the DOHC. If he as the 8-valve, yeah, the DOHC would be way better.

Loginology

I have the 16 valve SOHC.



So what do you guys recommend? I want to turbo ASAP, and I want my HP limit to be no shorter than 300hp. I'm not lookign to get 300 hp now, but I will be constantly improving my car untill I get around there. I awnt to jump to atleast 200hp within the next 3 months though.


Give me your recommendations on turboing.

zenilder

Get the BPT then. After that, when you have time or money, you can get the custom manifold and bigger turbo, of course by which time you'll need that stand alone system, bigger injectors, and a number of other intake-side goodies.

I can prolly go home and measure the valves for the SOHC. I have spare set that is all whored up (came from my cracked head that I had to toss).

True, the cam timing would be a good benefit, too. Wasn't thinking about that. What kind of timing would you want to do on a big turbo that you couldn't do with a cam grind for the SOHC?
I don't see too much need for cam timing adjustment.
Maybe I'm just not looking at it right. Hmm.

Anyhow...

Loginology

lol, seems like I keep going in this contious loop between modifying the current engine, converting to DOHC, and getting a BPT