My wifes car has a Subaru 2.5 330 h.p. and a medi 2D. I am trying to decide if I want to switch it to a Honda turbo engine. She has a little trouble with the low end on the Subaru however I have never driven a sandcar with a Honda, maybe I won't be gaining enough.
Anybody have experince with them both?
Any thoughts?

A little more info on the car would be helpfull. If she has a stock n/a motor with a small turbo on it, it should have pretty good power on the bottom and midrange. The hondas are great, but I doubt that the honda would be much better where she needs it.

Its a JP designs car, fairly light. It is turbed outback engine and I run 110 in it.

My question is does the Honda make much more torque on the bottom than the Subaru?

Maybe I should consider a different motor than the Honda?

I don't want to add too much weight or have to run a beefier transaxle.

The car itself is great.

Just ask John to upgrade that one to 450 hp or so.


The Subi has the awesome low center of gravity, if you switch to any V6 or V8 you're going to end up with more weight at the rear and a higher C of G, both will affect handling. If you just need more power, that is easily done with a phone call and some money.

The center of gravity is one of the biggest reasons I think this car handles so well. If I add horsepower to it will I sacrifice more low end? I drove a 600h.p. 3.0 liter and it was mean, but I don't remember how it was on the low end, and it was a 6 cylinder so not exactly apples to apples anyway.

I would enertain the idea of adding to the existing motor.

Maybe I should call Outfront Monday.

Of course John could tell you for sure, but if you had it rebuilt from 330 hp to over 450 hp, then I would think the hp curve would also start a little earlier in the power band. I'm not sure. I know his 640 hp engine hit like a sledgehammer, yet it was docile enough to just idle around if you wanted to.

Are you sure you're getting the full 330hp? Maybe it's time for a dyno session. As light as the JPDesigns cars are, I would think 330hp would make it scoot plenty fast.

I have not had it dyno'd. It does have and older version ecu on it.

Just modify the tuning, a smaller turbo that comes on quicker is better than one that makes more hp but takes forever to do it.

Of the hondas I have driven and rode in I would say stick with the subie and modify it to your needs.

If your 2.5L Subie motor is DOHC you could always swap it for a SOHC motor to get better low end torque. The SOHC motors have smaller intake ports which create higher velocity intake mixtures at low speeds. Hence you get better low end torque with the stock 10.5/1 compression pistons than the DOHC motors. I happen to prefer the SOHC version to get better low end torque, better dunability, less shifting, but I pay a small price in top end HP.

Many of the high horsepower Subie motors use lower compression 8.5/1 pistons and run higher boost. The downside of this is the bottom end suffers but the big advantage is the upper HP is better. To make up for the low RPM torque in these low compression motors you can put a smaller turbo which will spool sooner and quicker, ideally a ball bearing turbo. John at Outfront can provide the right model to accomplish what you want. But often when you change a turbo the exhaust and air filter plenum will need modification along with the intercooler (if you're running an intercooler).

My first Subie was a SOHC motor running 10lbs of boost in a stock block motor. I also ran the stock injectors and stock fuel regulator, modified to regulate at 40psi. I ran that for 3 seasons, and the last two seasons I ran 50/50 mix of 91 and 110 octane without an intercooler. I figured why should I be running 110 octane when other Subie guys were running 20lbs of boost with 110, and I only ran 10lbs. So I experimented with a 50/50 mix and never had a problem.

Although Honda motors can put out a lot of HP with a turbo, you will be increasing your rear end weight by about 150lbs. That's a lot of weight for a car that weighs 1800lbs. You have to put out more HP to make up for the increased weight, and at low speeds that's more difficult. Weight is also an enemy to the transmission, not to mention the ill affects it can have on handling with that additional weight on the rear end of the car. Don't forget the Honda is a longer motor sticking out farther behind the rear axles, which means more leverage against the front end.

So imho more CI isn't necessarily the answer for more low end torque in a rail.

I have never driven a turbo subie car but I do have a honda in my car and its great. My wife can stick it in 2nd gear and lug it almost to a stop and stand on it and it gets right up and goes. I think in your case though I would look into modifying your motor to better suit your purposes.

Ditto the smaller turbo... And don't put a pop off valve on it. <(Keeps the pressure up)

Zilla

Tell John you want the smaller turbo (potato), You'll sacrafice top end, but I can pop over drops in my funco like I was driving a quad lots of low end

Hi I have a turbo subaru SOHC with a STI short block in it 50lb injectors t3/t4 turbo big inercooler and am only running 6 lb of boost. The engine works awsome my car is 1800 lb 4seat. with just me in it it hauls butt and i can lug it all day long. Whith four full size adults it is a little small on the power side. I am thinking of cranking up the boost to around 15lb and running 110 gas. That should make it go when it is full. I can say that the SOHC compaired to the DOHC is a big diffreance my friend has the DOHC and he is unable to lug it where i can he has to down shift as where i can just smash the gas and it starts to pick up. Hope that helpes.
Garrett

i run a SOHC suby and concur with all of the above, especially the weight to HP ratio by adding a HONDA, I would just upgrade the suby

We have a n/a 2.5 subi and John from Outfront really liked it because it had more torque than having turbo. You don't have to wait for that turbo lag to catch up, it's just there to get you up the hills.
we also had the 3.3 n/a before we went to turbo and that motor was awesome. Pulled four people up the hills no problem. Isn't about 75lbs. more I think and not that much longer. If your looking for torque, the 3.3 is it and it's still pretty low center of gravity.
Good luck with your swap

The ultimate setup would be to go with a smaller turbo, and install the Devil's Own water/methanol injection system.


Let's say a guy is running 8psi of boost, and he mixes race fuel/premium 50/50. What he is doing is blending his fuel for the octane rating needed when the engine is at 8 psi. But down low, when the engine is not getting boost, the higher octane is not helping out, it's actually decreasing power slightly. He's running too much octane in order to protect the engine. The timing is not optimized for that high octane fuel.

Now with a water/meth system installed, it injects the mixture proportionally as the boost increases, to slow the flame front just the correct amount at all levels of boost, smoothly.

So this guy could now do one of two things.

He could increase his timing and install a smaller turbo, for better bottom end response. He can still run the 50/50 fuel mixture and run 12 or 14 psi of boost. The water/meth would come on proportionally and give smoother and more power, from the cooling effect on the intake, the power addition of the methanol and the expansion of the steam spinning the turbo earlier/faster.

Or he could run the same timing, install the smaller turbo, run it on premium, max out at about 8 psi of boost, but save money because the water/meth is a lot cheaper than race fuel. The engine would produce slightly more power at 8psi than before, and would be slightly more responsive at the bottom end.

These numbers are just for illustration purposes, only to explain the advantages of a smaller turbo and water/meth injection. Talk to John at Outfront for specific power levels, boost settings, timing and water injection curves.