Subie Engine Modifications

I have been looking at what can be done with a Subie Normaly Aspirated Engine to increase it's Horsepower. 

I have been looking at the 2.5L DOHC but mostly the 2.5L SOHC.  

From my conversations with well known builders on both sides of the border the 2.5L DOHC could be made to provide 220-230hp but the SOHC seems to not be able to provide more than a solid 200hp maybe a few more but they are unwilling to quote any higher.  Now,  some say that using a stock ECU when it is not the same year as the engine may cause you to downgrade the engine and not be able to use the Variable Valve Timing which would penalize you greatly.  

BTW All aftermarket ECU's will operate the two selenoids that operate the VVT. 

Just saying ... still investigating and feel free to add to this. 

Original Post
edsnova posted:

Good luck. I've long been astonished by the utter lack of information about and interest in tuning N/A Subarus—and N/A everything else. I guess turbos cut such a wide swath through the market that there's not market remaining for traditional head-cam-intake-(and now ecu) upgrades.

As you noted, the whole world is going to forced induction. Watch what the high-end air-cooled VW builders and tuners are doing. It's increasingly turbo-oriented. 

You know that I've never been a Subaru guy... but I was driving down the road today when the whole blown-Subi thing "clicked". Everybody knows that turbos are where the power is (and where the development money is getting spent), but a turbocharged Type 1 is not streetable (at least in the way I'm thinking).

But once you go over to the water-cooled side, there's very little to stop you from just going all the way with it. The motors are a stout as an anvil, and cooling them with a turbo is just a matter of a bigger radiator(s). Some charge-cooling would be nice, which is a problem with packaging in a rear-engined car, but you could set up a nice methanol injection system to get around that.

I spent the better part of 10 years on a quest for 200 (semi) reliable HP from a Type 1, but I've always known it was a quixotic pursuit. I'm still a died-in-the-wool retro-grouch, and I love my air-cooled engine. But... if you want more than 175 hp or so, the best way to get it is with a Subaru. And if you are going to the work, you can get a 230 hp Outfront longblock with all the go-fast stuff, or you can get a 250 hp stock Subaru turbo mill. A stock EJ257 makes 300 hp/300 lb-ft.

'That ought to do it.

Thanks for all of this... I have been reading some more and calling some more and Essentially, the cost of getting to about 200hp is quasi reasonable for N/A but reasonable gets kind of to a high price limit when the real power is for sure going with a turbo and if you go relatively low power you can get less lag.  Also a good used turbo Subie can be had for a lot less $ as well.  So you will be paying a lot to stay N/A.... So at this point anybody who has 170 to 200 hp your at a standstill unless you swap engines.   

How about a 3.0L N/A flat 6 subie... 250hp, 250ft/lbs torque for 58lbs more weight.... 2 inches wider and 2 inch deeper.... just saying   

 

Subaru tuners and car owners have been fooling around with turbos for decades now, with lots of choice for Sti and WRX engines, but the industry-wide interest in turbos isn't driven by hot rod guys, but bean counters, both government and the big car companies.

Mileage mandates have forced the big guys, like Porsche, Ford, and others, to shrink block size but up HP by adding one or more turbos.  Performance is a by-product, not the goal.  Porsche went from 3.8 to 3.0 liters in their latest 911, but added twin turbos, while Ford went to a V-6 with turbo from a V-8 in their F-150, with no decrease in HP.  In that manner, they produce more efficient engines, without lowering HP.  Of course, the fuel savings are illusory if you put your foot in it, as most of us are prone to do.

IAG, a high-performance Subaru engine builder, now manufactures a 4-cylinder, 2.5 liter billet block for Subaru that will take up to 1500 HP.  Cost is about $14,000. Warning: stay away from their website, Stan, far away!

Jim Kelly posted:

IAG, a high-performance Subaru engine builder, now manufactures a 4-cylinder, 2.5 liter billet block for Subaru that will take up to 1500 HP.  Cost is about $14,000. Warning: stay away from their website, Stan, far away!

I'm good. 

A series of dubious financial decisions regarding real-estate for family members leaves me with little time and money for being an idiot with my checkbook.

... although 1500 hp sounds fantastic...

My engine is advertised as 230 hp.  I think its probably is more like 200 at the crank.  The car (spyder) is so light and the engine spools up so fast it really makes for an exhilarating ride.  My first 125 hp air cooled car was super fun.  My 165 hp suby was a more serious performer but I always wanted more.  The current power that I have is just within being manageable.  I really don't want anymore power in this car.  Any more power would require a different car with more rubber and better suspension.  Its all about balance.  I'm pretty darn close.  People must wonder what I'm listening to in my ear buds because I'm always laughing.

The situation I described above, with government mandating mileage increases and manufacturers "complying" with turbos reminds me of the old joke:

Charlie and Jack are two old farmers, whose back fences have abutted for generations.  One day, they meet at the fence. 

Charlie says: Well, Jack, how's it going?

Jack replies: Not too bad, Charlie.  The government pays me to only plant half my land, but the boys from the university come down and show me how to double my yield!

IaM-Ray posted:

I have been looking at what can be done with a Subie Normaly Aspirated Engine to increase it's Horsepower. 

I have been looking at the 2.5L DOHC but mostly the 2.5L SOHC.  

From my conversations with well known builders on both sides of the border the 2.5L DOHC could be made to provide 220-230hp but the SOHC seems to not be able to provide more than a solid 200hp maybe a few more but they are unwilling to quote any higher.  Now,  some say that using a stock ECU when it is not the same year as the engine may cause you to downgrade the engine and not be able to use the Variable Valve Timing which would penalize you greatly.  

BTW All aftermarket ECU's will operate the two selenoids that operate the VVT. 

Just saying ... still investigating and feel free to add to this. 

AZP INSTALLS in Kenilworth, New Jersey are brilliant SUBARU race guys

Gonna throw in with Merklin on this. The original cars had 70-80-90 horses. Hell, the original 4-cam had 110, with only about 90 ft-lbs peak torque (at 5300 rpm no less!). And those Gen 1 Spyders ran 140 mph. Even the hottest versions of the Fuhrman engine topped out at about 175 horses. 

It's possible to have too much of a good thing. 

edsnova posted:

Gonna throw in with Merklin on this. The original cars had 70-80-90 horses. Hell, the original 4-cam had 110, with only about 90 ft-lbs peak torque (at 5300 rpm no less!). And those Gen 1 Spyders ran 140 mph. Even the hottest versions of the Fuhrman engine topped out at about 175 horses. 

It's possible to have too much of a good thing. 

I'm pretty happy with too much of a good thing.  And remember we've got much better tires and brakes.  I'm sure they had much more driving skills.  Well maybe not all of them.  James Dean?

I guess I understand the sentiment (too much power), but it’s hard to make a blanket statement, even regarding the purpose of these cars.

I was out for a bit last night, just cruising in the early evening, and 125 hp would have been just fine. But I’ve also hustled my car in haste on mountain roads (east and west), and was thankful for every last pony under that deck-lid. I’ll readily agree that with a flexible frame, ancient suspension (see the recent thread regarding swing-axles vs IRS), and stockish brakes, 125 hp IS about the limit. Moving the capabilities of the car requires a complete rethink of the entire vehicle, but it’s not like every car represented on the SOC is a pan-based car with drum brakes.

I can guarantee that Jim Kelly’s car is up to the burden of 300 hp, and that Marty’s is able to handle his 200+.  

A fully loaded Speedster is not THAT light. Nobody has any problem with a stripped-down early 911 making 250+ hp and weighing a couple hundred pounds more.

Modern sports-cars weigh a bit over 3000 lbs (1.5-2.0x as a speedster) and make 400+ hp. “Too much power” is more a function of too little effort planned on other parts of the car. A fox-body Mustang was a death-trap with 200 hp. A modern GT500 is in no way “overpowered”.

Everbody has an opinion, here’s mine:  if you want to cruise, El Guapo style— 125 hp, a swing-axle, and front discs/rear drums will be just fine. There is more than enough to keep a guy occupied in his garage just trying to keep everything working.

If you want to hustle a bit through the mountains, you really do want IRS 4-wheel discs and 150 hp (+/-), along with sway bars (front and rear) and some work on the front end.

If you want to run with newer sports-cars, it’s going to take money. Lots and lots of money. 

AC 100hp.  150hp. 175hp. 

4sp.  Or 5 speed gives a diff experience at each level of hp

WC subie 135 hp 175hp 200hp N/A

Or Subie turbo

a 4sp or 5sp  

many permutations or choices

Having driven 60hp original 356a

Tested a100hp IM ...i found it anemic on any long hill

5 years with 145hp IM  3:44 

acceptable IMO

now Subie IM 170-180hp 5 speed for

3 years it has a Great torque band and it makes rowing through the gears a lot of fun with less sensitivity to being in the right rpm slot like on the AC 

Could I use 200-235hp  N/A sure it would get me off the line faster

I feel every car combo has a sweet spot mixture and with 911 front end maybe the sweet spot goes further out speed wise, handling brakes etc

Oh yeah then there are IM -6  

 

 

My car can't keep up with many faster cars either, but your right, if it is enjoyable to you that is what counts.  I have been taking 150 mile trips every 2 or 3rd day and most days as soon as I leave with the top down and the sun is shining ... I just can't contain the joy it gives me... I feel well, really thankful ... I am a kid again  There I said it.   

Ray said:  "Oh yeah then there are IM -6"  

Yes, an IM6 can put out a good amount of horsepower and torque, but it still needs to be driven in a controlled manner.  Solid frame, all Porsche 911 mechanicals, sway bars, etc. help to make it nicely balanced.

I'm off to Mosport tomorrow for a track day, and my intent is to drive as smoothly as I can.  But it's still nice to be able to really open it up in a safe place, something I can't and won't do on regular roads.

The rest of the time, I drive as I would with any other car, and enjoy the experience.

Bob: IM S6 posted:

Ray said:  "Oh yeah then there are IM -6"  

Yes, an IM6 can put out a good amount of horsepower and torque, but it still needs to be driven in a controlled manner.  Solid frame, all Porsche 911 mechanicals, sway bars, etc. help to make it nicely balanced.

I'm off to Mosport tomorrow for a track day, and my intent is to drive as smoothly as I can.  But it's still nice to be able to really open it up in a safe place, something I can't and won't do on regular roads.

The rest of the time, I drive as I would with any other car, and enjoy the experience.

Agree whole heartedly....but from a HANDLING standpoint, I have yet been unable to lift any of the wheels off of the pavement(probably do NOT have the balls to do it). I just cannot get over how firmly the car sits flying on/off cloverleaf exits at high speeds....nicely balanced is an understatement for my experience. It out handles anything that I have ever driven, although could just be my perception of a very light 2300 pound car, zipping around with the top-down.....just a few inches off of the ground, with big paws, low center of gravity, and plus 200 pounds of both torque and HP.

I truly get your "controlled manner" suggestion but that is indeed a subjective/grey area parameter, and of course your car has another 60 to 80 horses on mime which could be the difference......I have driven a LOTUS EXIGE which is a road hugger and I dare say that the IM6 handles as well or better(could be a reflection of the same brain drain that allows one to buy such a car). Be SAFE.

I live the swing axel understeer over steer with my original 356.... not to my liking and I have taken my new car to some pretty nice track speeds and it just wants to go...  

The Oregon down the mountain course on Hwy1 is a cornering haven! it was awesome fun. 

Ray, I've been following a guy on FB that's been in Europe since May 21st.  Here was his first itinerary.  He been posting from the Tuscany last few days.  He works in NY City but his Alfa was in London when the trip started.  

Attn: English/French/Italians
Flight booked,Europe bound May 21 for road trip part 2 "petrol boogaloo"
If anyone wanted to meet in real life let me know 🙂
Planned Itinerary so far:
May
22-24 London
24-27 Brighton
*Ferry accross the channel to La Harve
May 28(?) I hope to make it from La Harve to Orleans (loire valley) in the same day, but will be taking scenic routes (B roads) via Boucles de la Seine Normande Natural Regional Park and Parc naturel régional du Perche. Any sugggestions on places to see/stay along the way are appreciated.
*my background is in the wine and food industry if that helps with suggestions
May 29th or 30th Head from Orlean to Mas du Clus racetrack stoping at Auberge de Magnat (for lunch) and then on to Lyon.
From Lyon I dont really have a clue. *Lyon is actually not set in stone and I could possibly be presuaded to go elsewhere.
the only day set in Stone is June 7th I need to be in Torino.
*I will also be in Berlin but probably without a car Filippo Moscatello
**visiting Spain or Greece is also on the agenda via ferry from italy, just not sure when.

A coda:

A 2018 911 GT2RS weighs 3241 lbs, and has 700 hp. That’s 4.63 lb/hp.  For a 2000 lb speedster to be similarly “overpowered”, it would need to make 431 hp.

In more pedestrian times, the magic number for “balance” was 10 lb/hp (or more than twice the weight/hp). That’s 200 hp in a 2000 lb car, which seems just about right to me.

Your mileage may vary. 

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