And I thought I wanted a Subaru.
I was trolling the web, and wanted to share some info on the Subaru for our application - This is not mine, but it had a lot of good information re: various Subaru configurations - just thought I would share for anybody that was thinking of going Subaru - Still the right call for me - despite the fear of the belt....
Also, after speaking with Out Front - the belt on mine seems "doable" - I know Nutz this despite your tale of caution....
I am still thinking but have the parts ordered and have a pdf diagram of the timing marks, etc and keyway - Out Front says no special tool is required to hold the cams - there is a keyway lock. Anyway - pdf attched, and info below. BTY, if you do go Subaru - the advice on Out Front below is spot on. Those guys rock.
Does this make me the resident Subaru Cheerleader?
(No not "Subaru answer man" - just a fan: Nutz sounds like the answer man.... Thanks again Nutz for the info)
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In response to the question -
"I have now noticed 2.5 Subi motors in dual and quad cam form.
What are other differences besides the cams?
Is one more desirable than the other?"
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It really depends on how much money you want to spend and what your goals are. Both motors are fun with a turbo. Both can use the stock block, pistons and rods to build a mild motor (300HP). Both typically require race gas with a turbo (there are some exeptions) But you ask a good question.
2.5L SOHC motors (what you're calling a dual cam) have slightly smaller intake/exhaust ports and deliver more low end torque. They are also simpler to work on and with the right piston setup using a butterfly cut for 100% valve clearance, you can be immune from bending valves in the case of a broken cam belt, simply because the valves cannot touch each other with a SOHC motor.
SOHC motors have the igniter circuitry in the OE coil setup. They work fine with after market EMS computer up to about 9-10lbs of boost. DOHC motors require you to buy a separate igniter to trigger the coils with an after market EMS computer.
SOHC motors have two OE sizes of injectors. If you get the model with larger injectors you can use those with up to 9lbs of boost, assuming you have a 50lb fuel regulator, or have the knack and know-how of modifying the stock OE fuel regular to deliver 40-45lbs of fuel pressure. Of course, whatever EMS computer you utilize, it will have to be tuned on a dyno specific to your injector/regulator combination. The point being..... a stock block SOHC motor can save you lots of money if you're looking for about 300HP by simply using the OE components and slapping a small turbo on it, plus you'll like the SOHC low end torque. If you ever wanted to go beyond 300HP, this is possible simply by upgrading the injector/fuel rails, pistons and rods with a close deck block, then turn up the turbo boost. These are the same upgrades you'd need with a DOHC motor for beyond 300HP, but with a DOHC motor you'd have to buy injectors, fuel rails and igniter just to get to 300HP with a stock block.
The DOHC motor has larger ports, the favorite for WAZOO motors, delivering about 50-75HP more than SOHC when running 20+ lbs of boost (requires closed deck block, race pistons, rods, etc). In all cases when building a mild or wild turbo motor with a DOHC motor you will have to buy aftermarket fuel rails and injectors, typically 50lb injectors unless you're going WAZOO for 550+HP, which may need even bigger injectors. DOHC motors are very popular because they can deliver more HP per pound than almost any motor in the business, not to mention they weigh 340lbs with turbo and intercooler (same as SOHC). Motor weight in a sandrail is critical IMHO, and the distribution of that weight even more critical, not to mention the center of gravity of the weight. DOHC motors are more fussy at melting cam covers if you don't use a GOOD heat sheild on the exhaust system. This is because the plastic cover is closer to the exhaust than the smaller SOHC plastic covers.
Both 2.5L motors, SOHC and DOHC, can only be boosted to 9-10lbs with a turbo when using a stock block. To run reliably beyond 10lbs of turbo boost you'll need to invest in a closed deck block, race pistons and race rods. With a 300HP setup, both motors can be tuned to run on 50-50 mix of 110/91 octane.
Both 2.5L motors, SOHC and DOHC can use the same block. Heads from a stock DOHC 2.0L turbo motor offer the best flow/dollar (extra large ports), and they bolt right onto a 2.5L block. The new 2.5L STI blocks are popular to upgrade a car with 2.0L motors when the time is up on the stock 2.0L block. STI blocks have a semi-closed deck that can be boosted to 20lbs, some do even more with higher risk.
The only other thing you need to know is...... buy your stuff from Outfront, they have everything you'll need. Don't be afraid to ask them motor questions, migration questions, compatibility questions, etc..... they'll help you.
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