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Old 10-14-2012, 03:42 PM   #1
JRVmotorsports
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Default Need some N/A Race engine help

I race a class 5 unlimited off road race car powered by a $36,000.00 type four VW style engine w/ Motec injection that requires being rebuilt every race ,and you can imagine what that costs, Rule changes for 2013 allow me to build a Subaru Race engine at 2.5 ltr. max , so I'm hoping that you guys knowing what you do about Normally Aspirated Subaru's can guide me in the right direction of 1) an engine builder that has good experince with this and 2) what Model of 2.5 works best for a N/A race engine . My current engine makes about 350 flywheel HP , I don't know if I can get there with the Subaru but I'm hoping to. Thanks in advance for the help
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Old 10-14-2012, 04:02 PM   #2
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There have been 300hp streetable 2.5liter engines. If your going to rebuild it after every event you could probably push the envelope even more and free up some power lost on more durable parts.

A great resource to get started at least would be to contact Tech Works Engineering. They manufacture and design many parts for a build such as the kind you have in mind. Pistons, cams, headers, valvetrain parts, etc.

Www.techworksengineering.com

Also, you will find much more useful, technically minded advice from people who have done this stuff before and know what works best over in the built motor forum. The oiling system will need to be massaged quite a bit too reliably spin the crank day enough to make power in the 300+ range.
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Old 10-14-2012, 05:24 PM   #3
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Thanks for the help , I'll give them a try
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Old 10-14-2012, 05:44 PM   #4
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Subscribing for a build sheet and updates. Please.....
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Old 10-14-2012, 06:04 PM   #5
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Subscribing for a build sheet and updates. Please.....
Just looking for some help as I have never worked with these engines before . Sorry to ruffle your feathers there big guy
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Old 10-15-2012, 09:31 PM   #6
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Quote:
Originally Posted by JRVmotorsports View Post
Just looking for some help as I have never worked with these engines before . Sorry to ruffle your feathers there big guy
Hey New Guy, let me educate you... People subscribe to your thread when what you are doing is of interest to them. They may have nothing to offer in the way of advice but they think what you are doing is interesting...

Contact Quirt Crawford at Crawford Performance. He got his start building the kind of engines and vehicle you currently run and was at the bleeding edge of Subaru NA engine performance before the turbo cars hit. His engines will cost you in the same realm as your current VW engine but they will be the real deal for what you want to do.
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Old 10-16-2012, 10:27 AM   #7
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LOL...What Matt said. No ruffled feathers just interested in what you are up too. As you can see based on your lack of responses threads like this are few and far between. I just wanted to show support and let you know that you will have at least one follower.

Matt, is this the same Crawford from back in the 80's that was building Chevy straight 6's when everyone else was building V-8's?
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Old 10-16-2012, 08:46 PM   #8
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Quote:
Originally Posted by Matt Monson View Post
Hey New Guy, let me educate you... People subscribe to your thread when what you are doing is of interest to them. They may have nothing to offer in the way of advice but they think what you are doing is interesting...

Contact Quirt Crawford at Crawford Performance. He got his start building the kind of engines and vehicle you currently run and was at the bleeding edge of Subaru NA engine performance before the turbo cars hit. His engines will cost you in the same realm as your current VW engine but they will be the real deal for what you want to do.
Thanks for the help , I will give him a call
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Old 10-16-2012, 08:55 PM   #9
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Quote:
Originally Posted by bidaci View Post
LOL...What Matt said. No ruffled feathers just interested in what you are up too. As you can see based on your lack of responses threads like this are few and far between. I just wanted to show support and let you know that you will have at least one follower.

Matt, is this the same Crawford from back in the 80's that was building Chevy straight 6's when everyone else was building V-8's?

Sorry , completely misunderstood your responce , I can't begin to tell you how many doors have been slammed in my face on this engine build as soon as I start talking normally aspirated (as turbos are not allowed in off road racing) they don't even want to mess with it , I really believe the Subaru will be the best torque package for us and can be a real power house if done right . I am hoping to hit the 300 hp rage and even better torque than the type four engine I have now

Thanks,
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Old 10-16-2012, 11:46 PM   #10
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Do you have to stick with the stock displacement?
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Old 10-17-2012, 11:25 PM   #11
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What fuel type?

The hardest part with Subaru engines is by default they were not engineered to make high rpm torque. Everything's optimized for 3-4k rpm. You effectively have to re-engineer the engine to turn it into a different engine to get high rpm efficiency. You're changing every bit in and out of the combustion chamber: throttle body, intake manifold, heads, valves, cams, pistons, header, exhaust. Everything has to be resized and geared for efficiency up top. Then you can rev, make good torque up there, and make high hp numbers. It just comes down to do you want to do that? I know of no one that has actually built a Subaru race engine. There has been good hp builds, but I haven't seen anyone ever build a full on race engine. I'd personally love to...you know...for science, but I can't justify not just dropping in an old EG33 with just a couple mods and make that kind of power on pump gas. It makes it extremely hard to justify the cost. In your case, you are bound to the displacement, so you're stuck with the engine. That's doable. You just have to completely re-engineer the whole thing. That's all. 300-350chp should be doable on race fuel. I don't know if you'll get more torque or not.

I'd love to see a real race 2.5L Subaru engine. I have an old Forester with a worn motor, and I've seriously looked at rebuilding it specifically for E85 and a peak torque point more around 7k than 3-4k. I just can't justify the cost, although I'd really like to see the results. The nice thing is there are a lot of parts readily available and good aftermarket support for most things. You would need custom pistons since nothing exists above 11.2:1. Wiseco is your best option both for lightness and because they are the maker of that 11.2:1 piston, the only off the shelf higher than stock piston available. I don't know if you plan on changing the wrist pin location and may or may not need custom rod lengths. Eagle makes the lighest ones, but there's lots of options out there. There are better designed cranks out there, ones with improved oiling. Crawford Performance is probably the best known, but several manufacturers do make aftermarket cranks that will hold up to more abuse.

The heads have to get completely redone. To breath you need oversized valves, porting, and an actual race cam. Rallitek has a packaged product that fits these goals, although they do not advertise their cam setup nor has anyone really used and dynoed them on a built up engine. I've seen zero results from its use. You can of course do your own work as all the parts are readily available.

The exhaust and intake all have to be upsized. The intake manifold is all wrong for high rpm power, so you're looking at larger and shorter runners. This will need to be custom. There are zero aftermarket intake manifolds for the NA market which in my opinion is kind of sad. Several exhausts are available and there are a couple good manufacturers out there. The best is TWE, and they make the best off the shelf exhaust for the NA engines. They also do custom work and can make whatever you want. Then again, there are a lot of places that can fab up exhaust for you. TWE is just a company that has supported the Subaru community and offers the best options available at the consumer level for these cars.

If I had $10k-$15k I could toss at an engine just for fun, I would enjoy building one.
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Old 03-14-2013, 11:18 AM   #12
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Any Up Dates?
I race with JRV and Against =) but are good friends.
Either way our rule book in our sactioning body has allowed us to run the Subies.
Has to be a 4 cly 2.5L max
So my questions are, What are the tricks? Are there better engine cases from diffrent years and if it was a turbo or not? What is the best head to run? DOHC, SOHC, any particular year? etc....

Last edited by Class5; 03-14-2013 at 11:42 AM.
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Old 03-14-2013, 09:22 PM   #13
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Is the displacement max based on stock bore? No room for longterm maintenance? Is stroke limited to stock? Is there a preferred RPM range?

My build is a good portion of the way to your goal and I could build 6 more just like it within your budget!

Techworks has built quite a few EJ25's to north of 325 at the crank and certainly worth talking to.

Crawford is another company well equipped to help you reach your goals.


Jay
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Old 03-15-2013, 12:40 AM   #14
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I would like to chime in here a bit even though I don't race a subaru or build subaru race engines, I have read though about some nice setups especially from Dom @ Maxwell power and Homemadewrx/ Micah on here.

Obviously, the main issue with the subaru engines is the rpm range. In order to get more power you either have to stroke the 2.5 into a 2.6 or 2.7 or rev much higher but since you are limited to a 2.5 L max, there's another option that I was thinking about building for a NA engine down the road which might be a good option for you.

Dom @ Maxwell Power and Micah/homemadewrx worked together to design a long rod subaru engine which has given some very interesting results. This was a turbo version though but Micah has built a few NA long rod engines I believe from the 2.5 shortblock. For the long rod, the rods are 4+mm longer than the stock rod on the wrx 2 L 75mm stroke crank (the regular 2.5 has a 79 mm stroke crank). It turns the 2.5 L into a 2.34. However, that leaves room to sleeve and go to a 4" bore or just a smit larger which will bring it back to just under a 2.5 L setup. Compared to other engines, 4+mm longer isn't very much but for a subaru engine it does allow the ability to rev to 9500 rpms and maybe 10,000 if the heads can support it.

So, I know you said that you are interested in higher end torque, well the set up that I was going to suggest is the 2.5 block with just a bit over a 4" bore, 4+ mm rods, 75mm crank, higher compression pistons like over 12:1 maybe some e85 fuel?, Ra gear set in the 5 spd case 3.083, 2.062, 1.545, 1.151, 0.825 with a 4.44 final drive, TWE header back exhaust, fully built heads and such, better intake manifold of course like others have said and then the tuning for it.

So, what kind of powerband are you specifically looking for? A wide torque band with instant torque or an engine that revs higher and produces more hp higher up to help with higher speeds? It is about building an engine to match whether it is a very heavy torquey type of engine or a higher revving, higher horse power engine with better gearing.

Last edited by subi400; 03-16-2013 at 01:46 AM.
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Old 03-17-2013, 11:49 PM   #15
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Any info yet Jim ?

This what I have come up with so far.....

83mm stroke and 98mm bore, custom pistons with a raised wrist pin, a hell of a lot of head work, and some custom Webb cams.

I'll make my own intake and I will need help on the FI part.
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Old 03-18-2013, 03:11 AM   #16
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Quote:
Originally Posted by Baja Stu View Post
Any info yet Jim ?

This what I have come up with so far.....

83mm stroke and 98mm bore, custom pistons with a raised wrist pin, a hell of a lot of head work, and some custom Webb cams.

I'll make my own intake and I will need help on the FI part.
Better check that side loading on the pistons, skirts and rod bearings But, it would be a very torquey motor though.
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Old 03-18-2013, 02:53 PM   #17
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Good god I would love to ride in that when it's done.
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Old 03-24-2013, 08:33 PM   #18
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God that thing looks like more fun than a kick in the balls!!!
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Old 03-29-2013, 04:05 PM   #19
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Sounds pretty awesome. Subscribed
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